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Sample records for late pleistocene stratigraphy

  1. Late Pleistocene stratigraphy of a carbonate platform margin, Exumas, Bahamas

    Aalto, K. R.; Dill, Robert F.

    1996-05-01

    Detailed field studies of the southern Exuma Cays on the eastern margin of the Great Bahama Bank show a complex history of late Pleistocene island construction. Pleistocene rocks include island core eolianites, overlain at island margins by fossil patch reefs and reef sands, which in turn are overlain by, and/or grade laterally into, talus breccia cones derived from the erosion of island core eolianite at paleo-seacliffs situated at approximately 5-6 m above present mean high tide. Laminated pedogenic calcrete widely caps Pleistocene rocks. Minor zones of penetrative subsurface calcretization, developed in association with root growth, occur along permeable horizons, including: contacts between talus units or crossbed sets, along tension joints, and (possibly) at the Pleistocene reef-eolianite contact. Among Pleistocene eolianite samples studied in thin-section, the relative proportions of ooids-intraclasts+grapestones-skeletal grains-peloids are approximately 48:39:6:7. Marginal to the Exuma Sound and on the Brigantine Cays, a greater proportion of ooids have peloidal nuclei and cortices with numerous laminae, which may reflect ooid derivation from shelf margin and broad platform interior regions that were characterized by high wave energy during ooid formation. Between these two areas, ooids are more commonly superficial and have cortices with few laminae and nuclei composed of subrounded micrite or pelmicrite intraclasts. Such ooid nuclei are most likely derived from storm erosion of partially cemented seafloor muds. Some skeletal-rich eolianite in this region may reflect local sediment input from platform margin reefs, or may be part of an older(?) stratigraphic unit.

  2. Late Pleistocene-Holocene alluvial stratigraphy of southern Baja California, Mexico

    Antinao, José Luis; McDonald, Eric; Rhodes, Edward J.; Brown, Nathan; Barrera, Wendy; Gosse, John C.; Zimmermann, Susan

    2016-08-01

    A late Pleistocene to Holocene alluvial stratigraphy has been established for the basins of La Paz and San José del Cabo, in the southern tip of the Baja California peninsula, Mexico. Six discrete alluvial units (Qt1 through Qt6) were differentiated across the region using a combination of geomorphologic mapping, sedimentological analysis, and soil development. These criteria were supported using radiocarbon, optically stimulated luminescence and cosmogenic depth-profile geochronology. Major aggradation started shortly after ∼70 ka (Qt2), and buildup of the main depositional units ended at ∼10 ka (Qt4). After deposition of Qt4, increasing regional incision of older units and the progressive development of a channelized alluvial landscape coincide with deposition of Qt5 and Qt6 units in a second, incisional phase. All units consist of multiple 1-3 m thick alluvial packages deposited as upper-flow stage beds that represent individual storms. Main aggradational units (Qt2-Qt4) occurred across broad (>2 km) channels in the form of sheetflood deposition while incisional stage deposits are confined to channels of ∼0.5-2 km width. Continuous deposition inside the thicker (>10 m) pre-Qt5 units is demonstrated by closely spaced dates in vertical profiles. In a few places, disconformities between these major units are nevertheless evident and indicated by partly eroded buried soils. The described units feature sedimentological traits similar to historical deposits formed by large tropical cyclone events, but also include characteristics of upper-regime flow sedimentation not shown by historical sediments, like long (>10 m) wavelength antidunes and transverse ribs. We interpret the whole sequence as indicating discrete periods during the late Pleistocene and Holocene when climatic conditions allowed larger and more frequent tropical cyclone events than those observed historically. These discrete periods are associated with times when insolation at the tropics was

  3. Late Pleistocene-Holocene seismic stratigraphy of the Southeast Vietnam Shelf

    Dung, Bui Viet; Stattegger, Karl; Unverricht, Daniel; Phach, Phung Van; Thanh, Nguyen Trung

    2013-11-01

    The Late Pleistocene-Holocene sedimentary architecture of the Southeast (SE) Vietnam Shelf was investigated using high-resolution seismic profiles and core samples. Three systems tracts and a prominent seismic reflection surface at the base of the sequence were revealed. This surface (SB1) is interpreted as a sequence boundary formed by subaerial processes during the Late Pleistocene sea-level fall and subsequent marine reworking during transgression. A surface map of the lowstand surface, compiled from seismic profiles and sediment cores, revealed the W-E to N-S oriented incised-valley system of the paleo-Mekong River. The incised valleys show a clear change in morphology from the north to the south in the study area. The northern incised-valley system off Vung Tau appears as a narrow and deep V-shape in cross-section (transition from fluvial deposits at the base to marine deposits in the upper part of the channels. On the exposed shelf and the interfluvial area of the incised-channels, the TST is a sandy layer overlying the sequence boundary SB1. Thickness of the TST on the shelf varies from 0 to 15 m. The highstand systems tract (HST) consists of thick mud clinoforms of the modern Mekong subaqueous delta. The HST wedge prograded onto the shelf primarily after the mid-Holocene sea-level highstand was at approximately 6.5-5.5 kyr BP ago. The HST wedge extends along the southwestern shore, and its maximum thickness (30 m) was recorded in the Cape Ca Mau area. The HST wedge pinches out at modern water depths of 20-30 m, resulting in a thin HST layer on the middle and outer shelf. The proposed post-Pleistocene sequence-stratigraphic model for the SE Vietnam Shelf is a variation on the theoretical model of Vail (1987). The thick highstand wedge on the SE Vietnam Shelf is confined to the inner shelf due to the broad and low-gradient shelf morphology and the strong local hydrodynamic conditions driven by the monsoon system. Except for the one deposited within the

  4. Sedimentology and Stratigraphy Architecture of the late Pleistocene-Holocene Succession of the Gargaresh Formation, Subratah Basin, NW Libya

    Hlal, Osama; Bennur, Sami

    2014-05-01

    Gargaresh Formation outcrops is comprises the outcrops between the Misurata (N32o22'18'' E15o12'03'') to the Tripoli(N32o 51'10'' E13o 03'22'') areas is represented by prominent carbonate aeolianite exposed in extensive outcrops along the NW Libyan shoreline. Gargaresh Formation outcrops comprises two Members an upper Kaam Member of Aeolian origin and a lower Karrot Member of marine origin. The study of the Gargaresh Formation can provide useful information on reconstructions of Late Pleistocene-Holocene history of NW Libya and new insights on palaeogeography. It is forming low ridges and cliffs along the coastline of NW Libya and occurs as cliffs continuously attached to the sea tide, and occasionally interrupted by broad wadis or deep-cut embayment. The Gargaresh Formation sediments are dominated by calcarenites with skeletal marine fauna and non-skeletal grains of lithoclasts, aggregate, with oolites. In addition, these rocks are characterized by very well aeolian controlling factors represented by wind blown sediments such as large scale cross lamination (aeolianite) . The majority of palaeocurrent direction was to SE, on the other hand the dune migration was SE also. The sediments of Gargaresh Formation outcrops from Misurata to Tripoli NW Libya mostly allochthonous except the paleosols red-brown unit. Most of its fossils are thanatoconoses. Gargaresh Formation sediments shows that the original aragonite composition of pelecypoda and gastropods fragments are mostly preserved, but partly transformed into granular calcite as pendulous (meniscus) cement texture in response to meteoric fresh-water. Keywords: Sedimentology; Stratigraphic architecture; Aeolian origin; marine origin; Calcarenites; Late Pleistocene-Holocene

  5. Late Pleistocene Alberca de Guadalupe maar volcano (Zacapu basin, Michoacán): Stratigraphy, tectonic setting, and paleo-hydrogeological environment

    Kshirsagar, Pooja; Siebe, Claus; Guilbaud, Marie Noëlle; Salinas, Sergio; Layer, Paul W.

    2015-10-01

    The Late Pleistocene (~ 21,000 yr BP) Alberca de Guadalupe maar is one of the few phreatomagmatic volcanoes occurring within the scoria-cone dominated Plio-Quaternary Michoacán-Guanajuato Volcanic Field. The scarcity of this type of volcano implies that conditions favoring their formation are rarely met in this region. We identify these factors by implementing current methods of investigation with emphasis on hydrogeological conditions. We present the stratigraphy (including a set of 40Ar/39Ar and 14C dates) of the SE margin of the Zacapu intermontane tectonic basin, where the maar just forms a hole (~ 1 km in diameter, ~ 150 m deep, bearing a ~ 9 m deep lake) in the otherwise planar topography of the underlying early Pleistocene lava flows of the Cerro Pelón scoria cone. The maar is composed of typical phreatomagmatic surge deposits that are poorly sorted and rich in accidental lithics (> 60 wt.% of the deposit) with few juveniles (basaltic andesite, SiO2 = 54-58 wt.%). The entire structure is cut by an ENE-WSW trending normal fault and is underlain by andesite lavas and silicic ignimbrites (partly inferred from xenoliths encountered in the maar deposits) that are Miocene to Early Pleistocene in age. The crater is at the center of a N-S elongated drainage basin surrounded by topographic highlands that channel water with high hydraulic pressure from most directions towards the location of the maar. This geometric configuration was already in existence at the time of the maar-forming eruption, but the climate was different. Colder and more humid conditions during the Last Glacial Maximum (Cw2-climate type, annual precipitation of > 1000 mm) favored the saturation of the fractured shallow aquifer system (hydraulic conductivity of 10- 8 to 10- 7 m/s) that supplied sufficient groundwater at a high flow rate directed towards the center of the basin. Upon contact near surface ( 150 m deep crater with steep inner walls and an underlying shallow diatreme (sustain a ~ 9-m

  6. High-resolution seismic stratigraphy of a late Pleistocene submarine fan ponded by salt-withdrawal mini-basins on the Gulf of Mexico continental slope

    Winker, C.D.

    1996-12-31

    The late Pleistocene Brazos-Trinity Fan, a structurally ponded fan completely exposed and undisturbed on the seafloor, was mapped with a combination of conventional and high-resolution seismic data. This fan occupies three salt-withdrawal mini-basins (1, 2, 4) and a graben (3), each filled with an onlapping package consisting of alternating bedded and non-bedded units evident on high-resolution data. Basins 1--3 are filled to their topographic spill points; the onlap-fill succession of each is incised by a channel system which bypassed sediment to the next basin(s) downdip. Seismic continuity generally increases distally in the system and within individual basins, believed to reflect the increasing prevalence of turbidity currents over high-density sediment gravity flows.

  7. Sequence stratigraphy and environmental background of the late Pleistocene and Holocene occupation in the Southeast Primor'ye (the Russian Far East)

    Chlachula, Jiri; Krupyanko, Alexander A.

    2016-06-01

    The paper presents the results of Quaternary palaeoecology and geoarchaeology studies in the Zerkal'naya Basin, with new insights about sequenced natural shifts during the prehistoric occupation of this marginally explored NE Asian maritime territory. The Basin is part of the continental drainage system and the main physiographic and biotic corridor for peopling of the transitive coastal interior SE Primor'ye Region. The Final Pleistocene and Holocene environmental (biotic and abiotic) proxy records from the Upper/Final Palaeolithic to early historical sites document a dynamic climate change with vegetation cover transformations within riverine and mountain valley ecosystems of the Russian Far East. Most of the archaeological sites located on the low terraces and bedrock promontories along the main river channel and its tributary streams suggest traditional hunter gathered lifestyles based on seasonal salmon-fishing supplemented by pastoral economy. Tundra-forests with larch trees, dwarf birch thickets and polypod ferns from the basal stratigraphic units of the late Last Glacial occupation sites associated with the Upper Palaeolithic micro-blade and bifacial stone tool traditions (14C-dated to 19,000-12,000 cal yrs BP) indicate rather pronounced conditions and much lower MAT comparing today. Following a final Pleistocene cooling event, a major climate warming marked the onset of Holocene accompanied by a regional humidity increase promoting the formation of a mixed broadleaved-coniferous oak-dominant taiga, and culminating in the mid-Holocene Climatic Optimum. The appearance of mosaic parklands ca. 5,000-4,000 cal yrs BP. may be partly attributed to the expansion of the Far Eastern Neolithic cultures practicing forest clearance for pastures and dwellings. A progressing landscape opening indicated by the spread of light-demanding thickets and birch-dominated riverine biotopes with Artemisia suggests a further vegetation cover transformation during the late Neolithic

  8. Late Carboniferous to Late Permian carbon isotope stratigraphy

    Buggisch, Werner; Krainer, Karl; Schaffhauser, Maria;

    2015-01-01

    An integrated study of the litho-, bio-, and isotope stratigraphy of carbonates in the Southern Alps was undertaken in order to better constrain δ13C variations during the Late Carboniferous to Late Permian. The presented high resolution isotope curves are based on 1299 δ13Ccarb and 396 δ13Corg...

  9. Pleistocene pollen stratigraphy from borehole 81/34, devil's hole area, central north sea

    Ekman, Sten R.

    1998-09-01

    Twelve pollen assemblage zones are identified in a 229 m deep borehole (BH 81/34) from the Devil's Hole area in the central North Sea (British sector). The sediment from this borehole is Early to Late Pleistocene in age and the observation of massulae from Azolla filiculoides in sediment with reversed polarity indicates an age younger than the Olduvai geomagnetic event for the entire sequence. The Early Pleistocene sediments were at least partly deposited in the vicinity of a river outlet and can be correlated either with the Eburonian or the Menapian cold stage and with the Bavel interglacial and the Linge glacial within the Bavelian stage in the Dutch stratigraphy. The Middle Pleistocene sequence contains an interval rich in Abies, Picea and Pinus, probably deposited during the end of either Cromerian Complex interglacial IV (Noordbergum) or possibly the Holsteinian. The uppermost 80 m of the core contains high frequencies of pre-Quaternary and deteriorated palynomorphs indicating extensive glacial or glaciofluvially reworked sediment.

  10. A Late Pleistocene sea level stack

    Spratt, R. M.; L. E. Lisiecki

    2015-01-01

    Late Pleistocene sea level has been reconstructed from ocean sediment core data using a wide variety of proxies and models. However, the accuracy of individual reconstructions is limited by measurement error, local variations in salinity and temperature, and assumptions particular to each technique. Here we present a sea level stack (average) which increases the signal-to-noise ratio of individual reconstructions. Specifically, we perform principal componen...

  11. Late Neogene, Seismic stratigraphy, Biostratigraphy, Mollusca, Evolution, Pannonian basin

    Velić, I.; Durn, G.

    1993-01-01

    The combined use of seismic stratigraphy and mollusc biostratigraphy in Late Neogene lacustrine deposits of the Pannonian basin offers three new approaches: First, the comparison of seismic facies and biofacies facilitates to make a distinction between biostratigraphic units and biofacies. Second, seismic datum levels permit crosschecking of discrete (magnetic, radiometric, and biostratigraphic) data, thus dating evolutionary events. Third, seismic monitoring of the sedimentary hi...

  12. Seismic stratigraphy, Pleistocene climate, and Tertiary sea level changes

    Lowrie, A.

    1985-02-01

    The Quaternary is characterized by 2 climatic signatures: that of the last 800,000 yr, the upper Pleistocene climatic signature (UPCS), and that of the period from 900,000 to 1,800,000 yr ago, the middle Pleistocene climatic signature (MPCS). Glacial cycles within the UPSC are about 100,000 yr long with interglacials of 10,000-12,000 yr duration and a full glacial period of 20,000-30,000 yr. The cycles of the MPSC range from 20,000 to 40,000 yr duration. Interaction between the 3 planetary orbital parameters of eccentricity, tilt, and precession are believed to cause the observed climatic signatures. From DSDP cores, 8 major Miocene hiatuses have been described. There is a roughly equal duration of hiatuses and deposition, with periods ranging from 0.5 to 2 m.y. +/- 0.5 m.y. The deep-ocean hiatuses correlate well with the seismically determined lowered sea levels of P. Vail. The hiatuses are interpreted to be caused by increased activity of ocean-bottom currents, in turn initiated by increased glacial activity. Thus, it is geologically reasonably that within each period of increased glacial activity there are 100,000-yr long UPSC-type cycles. The UPCS cycles have been tentatively identified in seismic data on the Louisiana, east Greenland, and Caribbean shelves and on the Indus Cone. Miocene glacial cycles should be sought in seismic data using innovative data processing techniques.

  13. K-Ar age of the late Pleistocene eruption of Toba, North Sumatra

    It is stated that the late Pleistocene eruption of Toba is the largest magnitude explosive eruption documented from the Quaternary. K-Ar dating of the uppermost unit of the Toba Tuff gives an age of approximately 75,000 yr. A chemically and petrographically equivalent ash layer in deep-sea cores helps calibrate the Stage 4-5 boundary of the standard oxygen isotope stratigraphy. A similar ash in Malaya that overlies finds of Tampan Palaeolithic tools indicates that they are older than 75,000 yr. (author)

  14. Middle to Late Pleistocene coastal deposits of Eivissa (Western Mediterranean): Chronology and evolution.

    Del Valle, Laura; Pomar, Francisco; Fornós, Joan J.; Gómez-Pujol, Lluís; Anechitei-Deacu, Valentina; Timar-Gabor, Alida

    2016-04-01

    This study deals with the sedimentary and stratigraphical description of Pleistocene deposits from seven coastal areas of Eivissa (Balearic Islands). Twenty two sedimentary facies have been described involving the succession of eolian, colluvial and edaphic environments. Carbonate sandstones, breccias and silty deposits are the main component of these sequences. Despite the extensive eolian systems outcropping along the coast of Eivissa, there are very few studies performed to chronological framework of these deposits. Luminescence measurements were carried out using an automated RisØ TL/OSL-DA-20 reader in the Luminescence Dating Laboratory of Babes-Bolyai University (Cluj-Napoca, Romania) under low intensity red light. OSL dating of nineteen eolian levels indicate that their deposition took place between the Middle and Late Pleistocene, establishing a paleoclimatic evolution of Eivissa Island since 755 ka to 70 Ka. Eolian activity in the Eivissa Island can be correlated with regression episodes which took place during cold periods associated with different isotopic stages, concretely the MIS 18, 16, 12, 10, 8, 6 and 4. Similar results have been obtained from many sites along the western Mediterranean Sea such as Mallorca (Pomar i Cuerda, 1979; Nielsen et al, 2004; Fornós et al, 2009), Sardinia (Andreucci et al, 2009; Pascucci et al, 2014), Liguria (Pappalardo et al., 2013). Keywords: Eolian dunes, Pleistocene, Climatic evolution, Eivissa. References - Andreucci, S.; Pascucci, V.; Murray, A. S.; Clemmensen, L. B. 2009. Late Pleistocene coastal evolution of San Giovanni di Sinis, west Sardinia (Western Mediterranean). Sedimentary Geology, 216: 104- 116 - Fornós, J.J.; Clemmensen, L.B.; Gómez-Pujol, L.; Murray, A. 2009. Late Pleistocene carbonate aeolianites on Mallorca, Western Mediterranean: a luminescence chronology. Quaternary Science reviews 28: 2697-2709. -Nielsen, K.A.; Clemmensen, L.B.; Fornós, J.J. 2004. Middle Pleistocene magnetostratigraphy and

  15. Depositional architecture and sequence stratigraphy of Pleistocene coarse-grained deltas along the Ligurian coast (Italy)

    A Ciampalini; M Firpo

    2015-12-01

    This study aims to develop a better understanding of the stratigraphy of the southern side of the Maritime Alps and of the Ligurian Sea during the Plio-Pleistocene. Five stratigraphic sections were measured and studied in the Segno River valley (Liguria, Italy). These sections are composed of Lower to Middle Pleistocene marine and continental deposits. Based on detailed mapping and sedimentological analysis, 12 marine and deltaic facies were identified. These facies were grouped into facies associations. Two allostratigraphic units were recognized, namely U1 and U2 from oldest to youngest. The lower unit (U1) represents the evolution of a coarse-grained delta developed in a valley or embayment. Within the deltaic sequence, transgressive and highstand systems tracts were recognized. The coarsening/shallowing upward trend observed within the sections suggests that the delta prograded rapidly in the landward portion of the canyon adjacent to the paleo-river outlet. The upper boundary of U1 is represented by a subaerial unconformity overlain by U2, which is composed of sediments deposited by several alluvial fan systems.

  16. Stratigraphy, sedimentology, paleontology, and paleomagnetism of Pliocene-early Pleistocene lacustrine deposits in two cores from western Utah

    Thompson, R.S.; Oviatt, Charles G.; Roberts, A.P.; Buchner, J.; Kelsey, R.; Bracht, C.J.; Forester, R.M.; Bradbury, J.P.

    1995-01-01

    The paleoclimatic history of western Utah is being investigated as part of the USGS Global Change and Climate History Program studies of long-term climatic changes in the western United States. The initial objective of the study is to document the environmental conditions during the mid-Pliocene period of warmer-than-modern global climates (the focus of the USGS Pliocene Research, Interpretation, and Synoptic Mapping [PRISM] project). The investigation also seeks to determine how and when these conditions gave way to the late Quaternary pattern of climatic variations (in which short periods of very moist climates have been separated by long periods of arid conditions). This is a collaborative project involving specialists from the USGS, Kansas State University, and the University of California-Davis in paleontology (Thompson, Buchner, Forester, Bradbury), stratigraphy and sedimentology (Oviatt, Kelsey, Bracht), and paleomagnetism and environmental magnetism (Roberts). The data presented herein represent preliminary findings of the analyses of two cores of Pliocene and early Pleistocene sediments from the eastern Great Basin.

  17. Sr isotope stratigraphy and lithogenic grain-size distributions of the Pleistocene Turkana Basin, Kenya

    Lubbe, J. V. D.; Sier, M.; Feibel, C. S.; Beck, C.; Dupont-Nivet, G.; Vonhof, H.; Joordens, J. J.; Cohen, A.; Prins, M. A.; Olago, D.

    2015-12-01

    The Pleistocene sedimentary infillings of the Turkana basin, a hotspot for early human evolution, document both human evolutionary and climatic events between 2.1-1.4 Ma. During this time interval, several early Homo species inhabited the vicinity of the Lorenyang paleo-lake, which was mainly fed by the Omo River, draining the Ethiopian Highlands. Paleo-Omo discharge could be expected to be modulated by changes in orbital eccentricity, causing wet-dry climate variability at ~20 kyr timescales, superimposed upon a long-term transition to drier conditions. To reconstruct climate and environmental changes during this key period of human evolution, we obtained high-resolution records of strontium (Sr) isotope ratios in lacustrine fossils as well as lithogenic grain-size distributions. High resolution sampling of sediment sequences containing abundant lacustrine fossils was carried out at outcrops situated to the east and the west of the lake. The sequences can be stratigraphically linked by several volcanic tuff layers, as well as paleomagnetic data. The Turkana basin is a half-graben and, as a consequence, the lacustrine sediment sequences along the western margin are relatively more continuous and deposited in a relatively deeper part of the lake, when compared to sequences at the eastern margin, where the paleo-Omo delta was situated. The outcrops to the west of Lake Turkana are situated in close proximity to core WTK13-1A, which was retrieved for the Hominin Sites and Paleolakes Drilling Project (HSDPD), and span approximately the same stratigraphic interval. In this study, we successfully linked the stratigraphies of the sediment core and the outcrops, the latter of which were logged in great detail in the field. In addition, time-synchronous Sr isotope records from both sides of Lake Lorenyang display similar trends in Sr isotope stratigraphy, thereby confirming the lateral correlations. However, large differences in grain-size distribution and accumulation of

  18. Contributi del Paleomagnetismo alla Stratigrafia del Pleistocene Medio-Superiore (Brunhes Chron)

    Sagnotti, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia

    2008-01-01

    The contribute of paleomagnetism to the stratigraphy of the middle-late Pleistocene (Brunhes Chron). This manuscript presents an updated summary on the contribute brought by paleomagnetism to the definition of a high-resolution magnetic stratigraphy for the middle-late Pleistocene. The middle-late Pleistocene spans a time intervals during which the Earth magnetic field held predominantly a stable normal polarity and includes the whole normal polarity Brunhes Chron. In absence of full...

  19. The Pliocene and Pleistocene of Pampean region (Argentina): systematic aspects on taphonomy and bio stratigraphy

    Canids in South America were first recorded in the Vorohuean (Middle Pliocene) at southeast marine cliff of Pampean region. These records were assigned to Dusicyon cultridens. D. gymnocercus has it oldest record in the Ensenadan (Early to Middle Pleistocene) of the Pampean Region (Argentina) and Tarija (Bolivia). Remains of this species are frequents in the Bonaerian and Lujanian (Middle to Late Pleistocene) of the Buenos Aires and Entre Rios provinces. Outside Argentina D. gymnocercus was recorded in the Lujanian of Brazil and Uruguay. Two new records of Dusicyon from Punta San Andres (Buenos Aires province) are presented here. The first one (MLP 07-V-2-1) comes from Arroyo Seco Formation(Bonaerian, Middle Pleistocene) and is assigned here to D. gymnocercus. MLP 07-V-2-1 constitutes the first record of this species at Arroyo Seco Formation. The other one (MLP 07-V-2-2) was exhumed from a paleocave excavated in San Andres Formationsediments (Sanandresian, Late Pliocene) and filled with sanandresian sediments. Also, rodent remains (Ctenomys chapadmalalensis and cavids) were collected inside of the paleocave. Although, the study carried out prevents the assignation of MLP 07-V-2-2 to any of the Dusicyon species, this remain shows some affinity with D. gymnocercus. If this is confirmed in the future MLP 07-V-2-2 could be the oldest record of D. gymnocercus. In addition we discuss some litoestratigraphic and bioestratigraphic aspects of Punta San Andres and taphonomic implications related with the paleocave were MLP 07-V-2-2 was founded.(author)

  20. Late Quaternary stratigraphy and luminescence geochronology of the northeastern Mojave Desert

    Mahan, S.A.; Miller, D.M.; Menges, C.M.; Yount, J.C.

    2007-01-01

    The chronology of the Holocene and late Pleistocene deposits of the northeastern Mojave Desert have been largely obtained using radiocarbon ages. Our study refines and extends this framework using optically stimulated luminescence (OSL) to date deposits from Valjean Valley, Silurian Lake Playa, Red Pass, and California Valley. Of particular interest are eolian fine silts incorporated in ground-water discharge (GWD) deposits bracketed at 185-140 and 20-50 ka. Alluvial fan deposits proved amenable for OSL by dating both eolian sand lenses and reworked eolian sand in a matrix of gravel that occurs within the fan stratigraphy. Lacustrine sand in spits and bars also yielded acceptable OSL ages. These OSL ages fill gaps in the geochronology of desert deposits, which can provide data relevant to understanding the responses of several depositional systems to regional changes in climate. This study identifies the most promising deposits for future luminescence dating and suggests that for several regions of the Mojave Desert, sediments from previously undated landforms can be more accurately placed within correct geologic map units.

  1. Strontium isotope stratigraphy and geochemistry of the late Neogene ocean

    A curve describing the variation of the strontium isotopic composition of seawater for the late Neogene (9 to 2 Ma) was constructed from 87Sr/86Sr analyses of marine carbonate in five Deep Sea Drilling Project (DSDP) sites: 502, 519, 588, 590, and 593. The strontium isotopic composition of the oceans increased between 9 and 2 Ma with several changes in slope. From 9 to 5.5 Ma 87Sr/86Sr values were nearly constant at ≅ 0.708925. Between 5.5 and 4.5 Ma, 87Sr/86Sr ratios increased monotonically at a rate of ≅ 1 x 10-4 per million years. The steep slope during this interval provides the potential for high resolution strontium isotope stratigraphy across the Miocene/Pliocene boundary. The rate of change of 87Sr/86Sr decreases to near zero again during the interval 4.5-2.5 Ma, and ratios average 0.709025. The relatively rapid increase of 87Sr/86Sr between 5.5 and 4.5 Ma must be related to changes in the flux or average 87Sr/86Sr ratios of the major inputs of Sr to the oceans. Quantitative modelling of these inputs suggests that the increase was most probably caused by an increase in the dissolved riverine flux of strontium to the oceans, an increase in the average 87Sr/86Sr composition of river water, or some combination of these parameters. Modelling of this period as a transient-state requires a pulse-like increase in the input of 87Sr to the oceans between 5.5 and 4.5 Ma. Alternatively, the 5.5-4.5 Ma period can be modelled as a simple transition from one steady-state to another if the oceanic residence time of strontium was eight times less than the currently accepted value of 4 Ma. (orig./Shoe)

  2. Seismic Stratigraphy of Pleistocene Deltaic Deposits in Bahía Blanca Estuary, Argentina

    SALVADOR ALIOTTA

    2014-06-01

    Full Text Available The Bahía Blanca estuary (Argentina has a morphological configuration resulting from hydrological and sedimentary processes related to Late Quaternary sea level changes. This estuarine system occupies a large coastal plain with a dense net of tidal channels, low-altitude islands and large intertidal flats. Little is known about the sedimentary units of the marine subbottom. Therefore, a stratigraphical analysis of the northern coast of Bahía Blanca estuary was carried out using high resolution seismic (3.5 kHz in order to: i define Quaternary sequences, ii describe sedimentary structures, and iii determine the paleoenvironmental conditions of sedimentation. The seismic stratigraphic data collected and their correlation with drilling lithological data show five seismic sequences (S1, S2, S3, S4 and S5, of which S1-S2 were found to be associated with a continental paleoenvironment of Miocene-Pleistocene age. Sequences S3 and S4, whose lithology and seismic facies (paleochannel structures and prograding reflection configurations, were defined on these materials, to evidence the development of an ancient deltaic environment which was part of a large Pleistocene drainage system. The S5 sequence was formed during the Holocene transgressive-regressive process and complete the seismostratigraphic column defined in the present study.

  3. Nile behaviour and Late Palaeolithic humans in Upper Egypt during the Late Pleistocene

    Vermeersch, Pierre M.; Van Neer, Wim

    2015-12-01

    The reconstruction of the environment and the human population history of the Nile Valley during the Late Pleistocene have received a lot of attention in the literature thus far. There seems to be a consensus that during MIS2 extreme dry conditions prevailed over north-eastern Africa, which was apparently not occupied by humans. The Nile Valley seems to be an exception; numerous field data have been collected suggesting an important population density in Upper Egypt during MIS2. The occupation remains are often stratified in, or at least related to, aeolian and Nile deposits at some elevation above the present-day floodplain. They are rich in lithics and animal bones, mainly fish, illustrating the exploitation of the Nile Valley by the Late Palaeolithic inhabitants. The fluvial processes active during that period have traditionally been interpreted as a continuously rising highly braided river. In this paper we summarize the evidence thus far available for the Late Pleistocene on the population densities in the Nile Valley, and on the models of Nilotic behaviour. In the discussion we include data on the environmental conditions in Eastern Africa, on the aeolian processes in the Western Desert of Egypt derived from satellite images, 14C and OSL dates, in order to formulate a new model that explains the observed high remnants of aeolian and Nilotic deposits and the related Late Palaeolithic sites. This model hypothesizes that, during the Late Pleistocene, and especially the LGM, dunes from the Western Desert invaded the Nile Valley at several places in Upper Egypt. The much reduced activity of the White Nile and the Blue Nile was unable to evacuate incoming aeolian sand and, as a consequence, several dams were created in the Upper Egyptian Nile Valley. Behind such dams the created lakes offered ideal conditions for human subsistence. This model explains the occurrence of Late Palaeolithic hunter-fisher-gatherers in a very arid environment with very low Nile flows

  4. Seismic stratigraphy of the Bering Trough, Gulf of Alaska: Late Quaternary history of Bering Glacier dynamics

    Montelli, A.; Gulick, S. P. S.; Worthington, L. L.; Mix, A. C.; Zellers, S.; Jaeger, J. M.

    2014-12-01

    Sedimentary architecture of the cross-shelf Bering Trough is studied using 5 high resolution seismic profiles integrated with the drilling data acquired during Integrated Ocean Drilling Program (IODP) Expedition 341. The objectives of this work are to constrain the number of advance-retreat cycles that have occurred through the Late Quaternary, examine the impact of the Bering Glacier on the continental shelf and slope, and reconstruct Bering Glacier dynamics. By tying these sequences with δ18O stratigraphy, we can test the Bering Glacier's relation to global ice sheet evolution and better understand the degree to which the glacial advance-retreat cycles were in phase with global events. Our results show that: (1) Identification of erosional surfaces and glacigenic landforms that record positions of stillstand events and diagnose the style of retreat allow us to distinguish nine phases of glacial advances and subsequent retreats. (2) Mapping shows that glacier pathways and flow directions through time are influenced by the occurrence of thick grounding-zone deposits and shifting foci of erosion. (3) Continuous buildup of glacigenic sediment fills tectonically created accommodation space and allows the glacier to advance seaward for the last three advances. Discovery of systematic, prominent deposition of glacial diamict and ice-rafted debris (IRD) during phases of glacial retreat is supported by the drilling data and suggests reconsideration of IRD impact on slope sedimentation. (4) The trough mouth fan started its development during marine isotope stage (MIS) 6, progressively advancing to the position of present shelf edge during the subsequent MIS 4 and MIS 2 and is recognized by evidence of extensive deposition of glacigenic debris flows on the slope. (5) Sedimentation rates in the depocenter are exceptionally high and are estimated to be 1-2 m/k.y. through the middle Pleistocene on the shelf and 4-5 m/k.y. average through MIS 6 on the slope.

  5. CANIS LUPUS (MAMMALIA, CANIDAE FROM THE LATE PLEISTOCENE DEPOSIT OF AVETRANA (TARANTO, SOUTHERN ITALY

    DAVIDE F.BERTÈ

    2014-11-01

    Full Text Available Here we described the remains of Canis lupus from the bed 8 of Avetrana karst filling (Late Pleistocene; Taranto, Southern Italy. The studied specimens are larger than those collected from the early Late Pleistocene Apulian localities and those referred to the recent Italian wolf. Moreover, the remains from Avetrana are morphometrically close to Canis lupus maximus from France and to C. lupus collected from Central and Northern Italian localities, chronologically related to MIS 2 and MIS 3. Morphologically, the studied specimens slightly differ from both C. l. maximus and other Pleistocene Apulian wolves. The dimensional differences between the Avetrana wolves and those collected from the other early Late Pleistocene Apulian localities could be explained through a spread of a large-sized morphotype from the Northern Italy.

  6. Late Pleistocene and Holocene Fire History of the California Islands

    Scott, A. C.; Hardiman, M.; Pinter, N.; Anderson, R.

    2013-12-01

    Charcoal has been recovered from a range of late Pleistocene and Holocene sites on Santa Cruz Island and Santa Rosa Island, both islands part of California's Northern Channel Islands, U.S.A. Sediments have been dated using radiocarbon measurements based on wood charcoal, fungal sclerotia, glassy carbon and fecal pellets and are given as calendar years BP. This charcoal has been used to interpret the fire history of the Islands. Charcoal assemblages from samples dating from 24,690 to 12,900 years are dominated by coniferous wood charcoal. Little angiosperm charcoal was recovered in any of the samples. Fungal sclerotia are frequent in a number of samples from a range of ages both on Santa Cruz and Santa Rosa. Fecal pellets are common in most samples and abundant in others. Some of the fecal pellets have hexagonal sides and are likely to represent termite frass. The sediments are fluvial in origin and the distribution of charcoal is irregular making interpretation of fire return intervals and fire frequency difficult. The charcoal indicates a significant record of fire before the earliest documented human arrival on the islands. Charcoal reflectance data shows the occurrence of predominantly low temperature charcoals suggesting common surface fires in the coniferous forest. Soledad Pond sediments from Santa Rosa Island (Anderson et al., 2010) dating from 11,800 cal years BP show a distinctively different vegetation dominated by angiosperms and showing a very different fire history. Pinus stands, coastal sage scrub dominated by Baccharis sp. and grassland replaced the conifer forest as the climate warmed. The early Holocene became increasingly drier, particularly after ca. 9150 cal yr BP. By ca. 6900 cal yr BP grasslands recovered. Introduction of non-native species by ranchers occurred subsequent to AD 1850. Charcoal influx is high early in the Soledad Pond record, but declines during the early Holocene when minimal biomass suggests extended drought. A general

  7. Late Pleistocene Megafaunal Extinction Consistent With YDB Impact Hypothesis at Younger Dryas Onset

    Kennett, J. P.; Kennett, D. J.

    2008-12-01

    At least 35 mammal and 19 bird genera became extinct across North America near the end of the Pleistocene. Modern increases in stratigraphic and dating resolution suggest that this extinction occurred relatively rapidly near 12.9 ka (11 radiocarbon kyrs). Within the context of a long-standing debate about its cause, Firestone et al., (2007) proposed that this extinction resulted from an extraterrestrial (ET) impact over North America at 12.9 ka. This hypothesis predicts that the extinction of most of these animals should have occurred abruptly at 12.9 ka. To test this hypothesis, we have critically examined radiocarbon ages and the extinction stratigraphy of these taxa. From a large data pool, we selected only radiocarbon dates with low error margins with a preference for directly dated biological materials (e.g., bone, dung, etc.) and modern chemical purification techniques. A relatively small number of acceptable dates indicate that at least 16 animal genera and several other species became extinct close to 12.9 ka. These taxa include the most common animals of the late Pleistocene such as horses, camels, and mammoths. Also, the remains of extinct taxa are reportedly found up to, but not above, the base of a widely distributed carbon-rich layer called the black mat. This stratum forms an abrupt, major biostratigraphic boundary at the Younger Dryas onset (12.9 ka), which also contains multiple ET markers comprising the impact layer (the YDB). Surviving animal populations were abruptly reduced at the YDB (e.g., Bison), with major range restrictions and apparent evolutionary bottlenecks. The abruptness of this major extinction is inconsistent with the hypotheses of human overkill and climatic change. We argue that extinction ages older than 12.9 ka for many less common species result from the Signor-Lipps effect, but the impact hypothesis predicts that as new dates are acquired, they will approach ever closer to 12.9 ka. The megafaunal extinction is strongly

  8. Environmental reconstruction and biostratigraphy of late Middle Pleistocene lakeshore deposits at Schöningen.

    Urban, Brigitte; Bigga, Gerlinde

    2015-12-01

    The Pleistocene sequence of Schöningen provides a key link between unglaciated and glaciated areas in western Central Europe and is an important point of reference for the subdivision of the glaciated late Middle Pleistocene. This locality yields paleoecological and geological evidence of at least four interglacial periods prior to the Holocene and younger than the Elsterian glaciation. The Pleistocene deposits at Schöningen are valuable archives of climate, landscape, and human evolution, containing outstanding information on past environmental changes and human adaptation. This paper presents paleoenvironmental and biostratigraphical results from the Middle Pleistocene archaeological lakeshore site of Schöningen, focusing on the so-called reference profile Schöningen 13 II of 2003. We discuss the lithological, palynological, and macrobotanical evidence and present a revised subdivision and reinterpretation of late phases of the Reinsdorf Interglacial. PMID:26638875

  9. Late Cenozoic structure and stratigraphy of south-central Washington

    The structural framework of the Columbia Basin began developing before Columbia River Basalt Group (CRBG) volcanism. Prior to 17.5 Ma, the eastern part of the basin was a relatively stable area, with a basement of Paleozoic and older crystalline rock. The western part was an area of subsidence in which large volumes of sediment and volcanic rocks accumulated. Concurrent with eruption of the CRBG, anticlinal ridges of the Yakima Fold Belt (YFB) were growing under north-south compression. Topographic expression of these features was later masked by the large volume of CRBG basalt flowing west from fissures in the eastern Columbia Basin. The folds continued to develop after cessation of volcanism, leading to as much as 1,000 m of structural relief in the past 10 million years. Post-CRBG evolution of the Columbia Basin is recorded principally in folding and faulting in the YFB and sediments deposited in the basins. The accompanying tectonism resulted in lateral migration of major depositional systems into subsiding structural lows. Although known late Cenozoic faults are on anticlinal ridges, earthquake focal mechanisms and contemporary strain measurements indicate most stress release is occurring in the synclinal areas under north-south compression. There is no obvious correlation between focal mechanisms for earthquakes whose foci are in the CRBG and the location of known faults. High in situ stress values help to explain the occurrence of microseismicity in the Columbia Basin but not the pattern. Microseismicity appears to occur in unaltered fresh basalt. Faulted basalt associated with the YFB is highly brecciated and commonly altered to clay. The high stress, abundance of ground water in confined aquifers of the CRBG, and altered basalt in fault zones suggest that the frontal faults on the anticlinal ridges probably have some aseismic deformation. 85 refs

  10. Metagenomic analyses of the late Pleistocene permafrost - additional tools for reconstruction of environmental conditions

    Rivkina, Elizaveta; Petrovskaya, Lada; Vishnivetskaya, Tatiana; Krivushin, Kirill; Shmakova, Lyubov; Tutukina, Maria; Meyers, Arthur; Kondrashov, Fyodor

    2016-04-01

    A comparative analysis of the metagenomes from two 30 000-year-old permafrost samples, one of lake-alluvial origin and the other from late Pleistocene Ice Complex sediments, revealed significant differences within microbial communities. The late Pleistocene Ice Complex sediments (which have been characterized by the absence of methane with lower values of redox potential and Fe2+ content) showed a low abundance of methanogenic archaea and enzymes from both the carbon and nitrogen cycles, but a higher abundance of enzymes associated with the sulfur cycle. The metagenomic and geochemical analyses described in the paper provide evidence that the formation of the sampled late Pleistocene Ice Complex sediments likely took place under much more aerobic conditions than lake-alluvial sediments.

  11. Vertebrate tracks in Late Pleistocene-Holocene (?) carbonate aeolianites, Pafos, Cyprus

    Milàn, Jesper; Theodorou, Georgios; Loope, David B.;

    2015-01-01

    n 2005, numerous vertebrate tracks were discovered in carbonate aeolianites in and around the town of Paphos, in the south western part of Cyprus. The main track-bearing exposure is located in a protected archaeological site near the Agia Solomoni Church in side the city of Paphos, where cross......-ripple strata. The sediment does not yet have an absolute date, but is considered to be of Late Pleistocene to Early Holocene age, as are many other coastal aeolianites in the Mediterranean area. The Late Pleistocene endemic fauna in Cyprus was limited to the dwarf hippopotamus Phanourios minor Desmarest, 1822...

  12. REINTERPRETATION OF THE LATE PLEISTOCENE INGARANO CAVE DEPOSIT BASED ON THE FOSSIL BIRD ASSOCIATION (APULIA, SOUTH-EASTERN ITALY

    CLAUDIA BEDETTI

    2007-11-01

    Full Text Available We present a study of Late Pleistocene fossil bird remains from Ingarano (Apulia, SE Italy, based on the revision of previously published material and the study of unpublished fossils bones. New field observations make it possible to simplify the stratigraphy of the deposit compared to previous work. The systematic study of the fossil bird bones revealed the presence of 15 taxa, including two hypothetical ones: Circus aeruginosus, Buteo rufinus, Aquila chrysaëtos, Falco columbarius, Falco cherrug, Alectoris graeca, Perdix perdix, Columba livia, Otus scops, Nyctea scandiaca, Nyctea scandiaca vel Bubo bubo, Athene noctua, Pyrrhocorax graculus, Pyrrhocorax pyrrhocorax, Corvus corone, Corvus corone vel Corvus frugilegus, Corvus corax. Our detailed study also helps improve the taphonomical interpretation of the deposit: the remains from the lower layers were accumulated after mammalian predator activity and were transported over short distances, while the ones from the upper layers show sings of intense transport, such as fractures and surface abrasion. Two different bird assemblages were recognized, respectively from the lowermost and the upper layers of the clastic succession exposed in the Ingarano deposit; this difference is also confirmed by the fossil mammal remains. The systematic study makes it possible to make palaeoenvironmental and palaeoclimatic reconstructions: both assemblages indicate open environments, and the taxa of the lower layers indicate the presence of woods and wetlands with colder characteristics, while birds of the upper layers indicate drier and warmer conditions. This analysis, and the dating established through geochemical analyses and study of lithic artefacts, lead us to date the formation of the Ingarano deposit to the Late Pleistocene, in particular to the MIS 3. The presence of a layer dated to the MIS 2 at the base of the succession indicated in previous works cannot be confirmed. 

  13. Arsenic in Groundwater: The Deep Late Pleistocene Aquifers of the Western Bengal Basin.

    McArthur, J M; Ghosal, U; Sikdar, P K; Ball, J D

    2016-04-01

    in groundwaters from 145 wells across central West Bengal, India, those from Pleistocene aquifers at depths >70 m beneath paleo-interfluves contain polluted groundwater in overlying aquifers. We postulate that the As was liberated in situ by reduction of minimal iron oxyhydroxides in the gray Pleistocene sands by organic matter infiltrating from riverbeds during late Pleistocene or earliest Holocene times. Mitigation of the widespread As-pollution in shallow aquifers through exploitation of deep Pleistocene aquifers would improve if guided by an understanding of the distribution of buried paleo-channels and paleo-interfluves and the knowledge that As may be present naturally in groundwater at depths >150 m beneath deep paleo-channels. PMID:27010474

  14. Pleistocene carbonate stratigraphy of South Florida: Evidence for high-frequency sea-level cyclicity

    Hickey, Todd D.; Hine, Albert C.; Shinn, Eugene A.; Kruse, Sarah E.; Poore, Richard Z.

    2010-01-01

    Pleistocene carbonates of south Florida and islands of the Florida Keys are currently divided into five marine sequences designated, from oldest to youngest, the Q1–Q5 units. The units include a mosaic of freshwater and shallow marine deposits that accumulated on the Florida platform during high sea-level stands. The units are separated by regional-scale subaerial-exposure surfaces that formed during glacioeustatic lowstands. Analyses of cores recovered at Grossman Ridge Rock Reef and Joe Ree Rock Reef in the Florida Everglades reveal additional subaerial-exposure surfaces that are used to delineate subdivisions within units Q1 (Q1a–Q1b), Q2 (Q2a–Q2d), and Q4 (Q4a–Q4b). Units Q1–Q5 preserve evidence of at least 10 separate sea-level highstands, rather than 5 as indicated by previous studies. Compilation of available uranium-series dates on corals recovered from the Florida Keys indicates that the Q4 unit accreted during sea-level maxima associated with marine oxygen-isotope Stage 9 (Q4a) and isotope Stage 7 (Q4b). The Q5 unit formed during isotope Stage 5. No reliable dates are available for units Q1–Q3. We infer that unit Q3 was formed during the extended sea-level highstand of isotope Stage 11 and that units Q2 and Q1 predate isotope Stage 11.

  15. Radiocarbon dating of late pleistocene marine shells from the southern north sea

    Busschers, F.S.; Wesselingh, F.P.; Kars, R.H.; Versluijs-Helder, M.; Wallinga, J.; Bosch, J.H.A.; Timmner, J.; Nierop, K.G.J.; Meijer, T.; Bunnik, F.P.M.; Wolf, De H.

    2014-01-01

    This article presents a set of Late Pleistocene marine mollusk radiocarbon (AMS) age estimates of 30-50 C-14 kyr BP, whereas a MIS5 age (>75 ka) is indicated by quartz and feldspar OSL dating, biostratigraphy, U-Th dating, and age-depth relationships with sea level. These results indicate that th

  16. Radiocarbon dating of late pleistocene marine shells from the southern North Sea

    Busschers, F.S.; Wesselingh, F.P.; Kars, R.H.; Versluijs-Helder, M.; Wallinga, J.; Bosch, J.H.A.; Timmner, J.; Nierop, K.G.J.; Meijer, T.; Bunnik, F.P.M.; Wolf, H. de

    2014-01-01

    This article presents a set of Late Pleistocene marine mollusk radiocarbon (AMS) age estimates of 30-50 14C kyr BP, whereas a MIS5 age (>75 ka) is indicated by quartz and feldspar OSL dating, biostratigraphy, U-Th dating, and age-depth relationships with sea level. These results indicate that the 14

  17. Evidences of climatic variations during Late Pleistocene- Holocene in the eastern Bay of Bengal

    Chauhan, O.S; Borole, D.V.; Gujar, A; Mascarenhas, A; Mislankar, P.G.; Rao, Ch.M.

    Based upon the variations of clay minerals, sediment texture, heavy mineral assemblage and sup(230)Th excess in the Late Pleistocene sediments of a hemipelagic core from the eastern Bay of Bengal (2713 m water depth), 35 cm and 73-78 cm levels...

  18. Late Pleistocene echimyid rodents (Rodentia, Hystricognathi) from northern Brazil.

    Ferreira, Thais M F; Olivares, Adriana Itati; Kerber, Leonardo; Dutra, Rodrigo P; Avilla, Leonardo S

    2016-06-01

    Echimyidae (spiny rats, tree rats and the coypu) is the most diverse family of extant South American hystricognath rodents (caviomorphs). Today, they live in tropical forests (Amazonian, coastal and Andean forests), occasionally in more open xeric habitats in the Cerrado and Caatinga of northern South America, and open areas across the southern portion of the continent (Myocastor). The Quaternary fossil record of this family remains poorly studied. Here, we describe the fossil echimyids found in karst deposits from southern Tocantins, northern Brazil. The analyzed specimens are assigned to Thrichomys sp., Makalata cf. didelphoides and Proechimys sp. This is the first time that a fossil of Makalata is reported. The Pleistocene record of echimyids from this area is represented by fragmentary remains, which hinders their determination at specific levels. The data reported here contributes to the understanding of the ancient diversity of rodents of this region, evidenced until now in other groups, such as the artiodactyls, cingulates, carnivores, marsupials, and squamate reptiles. PMID:27276377

  19. Stratigraphy and evolution of emerged Pleistocene reefs at the Red Sea coast of Sudan

    Hamed, Basher; Bussert, Robert; Dominik, Wilhelm

    2016-02-01

    Emerged Pleistocene coral reefs constitute a prominent landform along the Red Sea coast of Sudan. They are well exposed with a thickness of up to 12 m and extend over a width of about 3 km parallel to the coastline. Four major reef units that represent different reef zones are distinguished. Unit 1 is located directly at the coastline and is assigned to the rock-reef rim, while unit 2 represents the reef-front zone. Unit 3 is attributed to the reef-flat zone and unit 4 to the back-reef zone. The stratigraphic position and age of the four units respectively the facies zones are based on field relationships and δ18O analysis. Results of δ18O analysis of coral, gastropod and bivalve samples were correlated to previous age dating of correlative reefs in Sudan and other parts of the Red Sea region. Estimation of reef ages was mainly based on δ18O values of the reef-front zone (unit 2) and the observed sedimentary succession of the reefs. δ18O values of two Porites coral samples from the reef-front zone strongly suggest equivalent ages of 120 and 122 ka that correspond to marine isotope stage MIS 5.5. Based on δ18O values and the field relationship to the reef-front zone, ages of reef-flat zone (unit 3) and back-reef zone (unit 4) could be assigned to MIS 9 and MIS 7 respectively. MIS 5.1 is suggested for the reef-rock rim (unit 1). The relationship of the reef zones to individual MIS might be explained by the predominance of a specific zone during a certain stage, while other facies were less well developed and/or later eroded by wave action. The reef unit most distal from the recent coastline formed during interglacial stage MIS 7, while former studies assign this unit to interglacial stage MIS 9. Unique flourishing, high diversity and excellent preservation of corals in the back-reef unit of MIS 7 reflect growth in troughs landward of the oldest reef-flat formed during previous interglacial stage MIS 9.

  20. Ancient DNA reveals that bowhead whale lineages survived Late Pleistocene climate change and habitat shifts

    Foote, Andrew D; Kaschner, Kristin; Schultze, Sebastian E;

    2013-01-01

    true Arctic species, the bowhead whale (Balaena mysticetus), shifted its range and tracked its core suitable habitat northwards during the rapid climate change of the Pleistocene-Holocene transition. Late Pleistocene lineages survived into the Holocene and effective female population size increased...... rapidly, concurrent with a threefold increase in core suitable habitat. This study highlights that responses to climate change are likely to be species specific and difficult to predict. We estimate that the core suitable habitat of bowhead whales will be almost halved by the end of this century...

  1. Late Quaternary stratigraphy and geochronology of the western Killpecker Dunes, Wyoming, USA

    Mayer, J.H.; Mahan, S.A.

    2004-01-01

    New stratigraphic and geochronologic data from the Killpecker Dunes in southwestern Wyoming facilitate a more precise understanding of the dune field's history. Prior investigations suggested that evidence for late Pleistocene eolian activity in the dune field was lacking. However, luminescence ages from eolian sand of ???15,000 yr, as well as Folsom (12,950-11,950 cal yr B.P.) and Agate Basin (12,600-10,700 cal yr) artifacts overlying eolian sand, indicate the dune field existed at least during the latest Pleistocene, with initial eolian sedimentation probably occurring under a dry periglacial climate. The period between ???13,000 and 8900 cal yr B.P. was characterized by relatively slow eolian sedimentation concomitant with soil formation. Erosion occurred between ???8182 and 6600 cal yr B.P. on the upwind region of the dune field, followed by relative stability and soil formation between ???5900 and 2700 cal yr B.P. The first of at least two latest Holocene episodes of eolian sedimentation occurred between ???2000 and 1500 yr, followed by a brief (???500 yr) episode of soil formation; a second episode of sedimentation, occurring by at least ???700 yr, may coincide with a hypothesized Medieval warm period. Recent stabilization of the western Killpecker Dunes likely occurred during the Little Ice Age (???350-100 yr B.P.). The eolian chronology of the western Killpecker Dunes correlates reasonably well with those of other major dune fields in the Wyoming Basin, suggesting that dune field reactivation resulted primarily due to departures toward aridity during the late Quaternary. Similar to dune fields on the central Great Plains, dune fields in the Wyoming Basin have been active under a periglacial climate during the late Pleistocene, as well as under near-modern conditions during the latest Holocene. ?? 2003 University of Washington. All rights reserved.

  2. Seismic and sequence stratigraphy of the central western continental margin of India: late-Quaternary evolution

    Karisiddaiah, S.M.; Veerayya, M.; Vora, K.H.

    -3227/02/$ ^ see front matter C223 2002 Elsevier Science B.V. All rights reserved. PII:S0025-3227(02)00591-1 * Corresponding author. E-mail address: kari@csnio.ren.nic.in (S.M. Karisiddaiah). MARGO 3240 25-11-02 Marine Geology 192 (2002) 335^353 www.elsevier.com... part of the lowstand stage. Afterwards, the in¢lling took place. The late Pleistocene^early Holocene Erosional Surface (ES) was subaerially exposed and weath- ered during the LGM (ca. 18000 yr BP). A sim- Fig. 8. A composi te general ised sc hematic...

  3. Seismic stratigraphy and depositional history of late Quaternary deposits in the Yellow Sea.

    Lee, Gwang-Soo; Yoo, Dong Geun; Bae, Sungho; Choul Kim, Dae; Yi, Hi-Il

    2016-04-01

    To identify the seismic stratigraphy and depositional history of late Quaternary deposits in the Yellow Sea, approximately 52,600 line-km of Chirp seismic profiles and 5,060 line-km of Sparker seismic profiles were analyzed. The Yellow Sea are correspond to three sedimentary environments: (1) a various scale sand ridges/waves and mud belt (the western inner-shelf of the Korean Peninsula), (2) recent- and paleo-channels, erosional and broad surface (the center of the Yellow Sea), and (3) prodelta mud patch (the eastern offshore of China). Based on the seismic stratigraphic analysis of seismic profiles, the late Quaternary deposits in the Yellow Sea are divided into five distinctive seismic units (units CY1~5), consisting of two depositional sequences that can be defined as erosional and disconformable strata. Each unit show different seismic facies and geometry, and is clearly separated by each bounding surface. The major depositional processes and sediment dispersal systems during the late Quaternary in the Yellow Sea are: (1) regressive estuarine/deltaic deposits (unit CY1), (2) transgressive incised channel fill (unit CY2), (3) transgressive sand sheet (unit CY3), (4) transgressive sand ridges (unit CY4), and (5) prodelta/recent mud (unit CY5). The depositional sequences follow the general concepts of sequence stratigraphy very well. Lower sequence (DI) correspond to the falling stage systems tract regarded as regressive estuarine or deltaic deposits (unit CY1), whereas upper sequence (DII) consists of a set of the transgressive (units CY2, CY3, and CY4) and highstand systems tract (unit CY5) formed since the last-glacial period.

  4. The late Middle Pleistocene hominin fossil record of eastern Asia: synthesis and review.

    Bae, Christopher J

    2010-01-01

    Traditionally, Middle Pleistocene hominin fossils that cannot be allocated to Homo erectus sensu lato or modern H. sapiens have been assigned to different specific taxa. For example, in eastern Asia, these hominin fossils have been classified as archaic, early, or premodern H. sapiens. An increasing number of Middle Pleistocene hominin fossils are currently being assigned to H. heidelbergensis. This is particularly the case for the African and European Middle Pleistocene hominin fossil record. There have been suggestions that perhaps the eastern Asian late Middle Pleistocene hominins can also be allocated to the H. heidelbergensis hypodigm. In this article, I review the current state of the late Middle Pleistocene hominin fossil record from eastern Asia and examine the various arguments for assigning these hominins to the different specific taxa. The two primary conclusions drawn from this review are as follows: 1) little evidence currently exists in the eastern Asian Middle Pleistocene hominin fossil record to support their assignment to H. heidelbergensis; and 2) rather than add to the growing list of hominin fossil taxa by using taxonomic names like H. daliensis for northeast Asian fossils and H. mabaensis for Southeast Asian fossils, it is better to err on the side of caution and continue to use the term archaic H. sapiens to represent all of these hominin fossils. What should be evident from this review is the need for an increase in the quality and quantity of the eastern Asian hominin fossil data set. Fortunately, with the increasing number of large-scale multidisciplinary paleoanthropological field and laboratory research projects in eastern Asia, the record is quickly becoming better understood. PMID:21086528

  5. Mid-Late Pleistocene OSL chronology in western Amazonia and implications for the transcontinental Amazon pathway

    Rossetti, Dilce F.; Cohen, Marcelo C. L.; Tatumi, Sonia H.; Sawakuchi, André O.; Cremon, Édipo H.; Mittani, Juan C. R.; Bertani, Thiago C.; Munita, Casimiro J. A. S.; Tudela, Diego R. G.; Yee, Márcio; Moya, Gabriela

    2015-12-01

    The origin of the transcontinental Amazon drainage system remains unrevealed. Sedimentary deposits formed from the Neogene in the Amazonas and Solimões Basins constitute natural archives for reconstructing this event in space and time. However, paleoenvironmental and chronological analyses focusing on these deposits, or even their basic mapping, are still scarce to allow such investigation. In this context, primary interests are fluvial strata related to the lithostratigraphic Içá Formation, mapped over a widespread area in western Amazonian lowlands. Although long regarded as Plio-Pleistocene in age, this unit has not yet been dated and its overall depositional setting remains largely undescribed. The main goal of the present work is to contribute for improving facies analysis and chronology of these deposits, approaching an area in southwestern Amazonia and another in northern Amazonia, which are located more than 1000 km apart. Despite this great distance, the sedimentological and chronological characteristics of deposits from these two areas are analogous. Hence, facies analysis revealed paleoenvironments including active channel, abandoned channel, point bar, crevasse splay and floodplain, which are altogether compatible with meandering fluvial systems. Similarly, optically stimulated luminescence (OSL) dating revealed thirty three ages ranging from 65.4 ± 16.9 to 219.6 ± 25.1 ky (in addition to three outliners of 54.0 ± 7.6, 337.3 ± 36.9 and 346.6 ± 48.6 ky), and nine 97.1 ± 9.9 to 254.8 ± 23.8 ky for the areas in southwestern and northern Amazonia, respectively. These data lead to establish that deposits mapped as Içá Formation over a vast area of western Brazilian Amazonia have a Mid-Late Pleistocene age, rather than the previously inferred Plio-Pleistocene age. It follows that if Plio-Pleistocene deposits exist in this region they remain to be dated and must be restricted to a narrow belt in western Amazonia, as well as isolated occurrences

  6. The Role of Seismic Stratigraphy in Understanding Biological Evolution in the Pannonian Lake (SE Europe, Late Miocene)

    Pogacsas, G.; Mueller, P; Magyar, I.

    1993-01-01

    The combined use of seismic stratigraphy and mollusc biostratigraphy in Late Neogene lacustrine deposits of the Pannonian basin offers three new approaches: First, the comparison of seismic facies and biofacies facilitates to make a distinction between biostratigraphic units and biofacies. Second, seismic datum levels permit crosschecking of discrete (magnetic, radiometric, and biostratigraphic) data, thus dating evolutionary events. Third, seismic monitoring of the sedimentary hi...

  7. New insights into mid-late Pleistocene fossil hominin paranasal sinus morphology.

    Zollikofer, Christoph P E; Ponce De León, Marcia S; Schmitz, Ralf W; Stringer, Christopher B

    2008-11-01

    Mid-late Pleistocene fossil hominins such as Homo neanderthalensis and H. heidelbergensis are often described as having extensively pneumatized crania compared with modern humans. However, the significance of pneumatization in recognizing patterns of phyletic diversification and/or functional specialization has remained controversial. Here, we test the null hypothesis that the paranasal sinuses of fossil and extant humans and great apes can be understood as biological spandrels, i.e., their morphology reflects evolutionary, developmental, and functional constraints imposed onto the surrounding bones. Morphological description of well-preserved mid-late Pleistocene hominin specimens are contrasted with our comparative sample of modern humans and great apes. Results from a geometric morphometric analysis of the correlation between paranasal sinus and cranial dimensions show that the spandrel hypothesis cannot be refuted. However, visualizing specific features of the paranasal sinus system with methods of biomedical imaging and computer graphics reveals new aspects of patterns of growth and development of fossil hominins. PMID:18951483

  8. Study of cave sediments in Budimirica Cave, Macedonia FYR – Correlation to late pleistocene environmental changes

    Temovski, M.; Bosák, Pavel; Pruner, Petr; Hercman, H.

    Postojna: Karst Research Institute, Research Centre of the Slovenian Academy of Sciences and Arts ,, 2015 - (Zupan Hajna, N.; Mihevc, A.; Gostinčar, P.). s. 150-151 ISBN 978-961-254-808-7. [International Karstological School Classical Karst /23./. 15.06.2015-19.06.2015, Postojna] Institutional support: RVO:67985831 Keywords : Budimirica Cave * cave sediments * magnetostratigraphy * Late Pleistocene * paleoenvironment Subject RIV: DB - Geology ; Mineralogy http://iks.zrc-sazu.si/datoteke/IKS-23-Guide-book-2015.pdf

  9. Large Late Pleistocene landslides from the marginal slope of the Flysch Carpathians

    Pánek, T.; Hartvich, Filip; Jankovská, Vlasta; Klimeš, Jan; Tábořík, Petr; Bubík, M.; Smolková, V.; Hradecký, J.

    2014-01-01

    Roč. 11, č. 6 (2014), s. 981-992. ISSN 1612-510X R&D Projects: GA MŠk LM2010008 Institutional support: RVO:67985891 ; RVO:67985939 Keywords : fossil landslide * radiocarbon dating * electrical resistivity tomography * pollen analysis * Late Pleistocene * Flysch Carpathians * Marine Isotope Stage 3 Subject RIV: DE - Earth Magnetism, Geodesy, Geography; EF - Botanics (BU-J) Impact factor: 2.870, year: 2014

  10. Environmental magnetism of Antarctic Late Pleistocene sediments and interhemispheric correlation of climatic events

    Sagnotti, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Macrì, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Camerlenghi, A.; Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Trieste; Rebesco, M.; Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Borgo Grotta Gigante 42/c, 34010 Sgonico (Trieste), Italy

    2001-01-01

    Recent developments in paleomagnetism and environmental magnetism provide new tools for the detailed correlation of climatically induced magnetic mineralogy changes in sedimentary sequences. Studies of these changes contribute to the reconstruction of climate history for the glacial^interglacial cycles of the Late Pleistocene and to the delineation of the range of natural variability for global climate during the past hundred thousands years. Here we show that sharp coercivity minima observed...

  11. Late Pleistocene eolian-alluvial interference in the Balearic Islands (Western Mediterranean)

    Pomar, Francisco; Del Valle, Laura; Fornós, Joan J.; Gómez-Pujol, Lluís; Anechitei-Deacu, Valentina; Timar-Gabor, Alida

    2016-04-01

    This study deals with alluvial fan and aeolian sediments interference. Although initially they are two different environments, with different processes and resulting forms, very often their interaction produces deposits that share characteristics and features from both environments, as well as, maintain inherited elements from one to each other. In this sense, the aeolian-alluvial interference is the geomorphological expression of the coincidence, disruption and/or overlapping of aeolian and alluvial environments. Climate appears to be one of the most important controls on the role and magnitude of each environment in terms of sediment supply, precipitation, runoff or aeolian transport. In this study, eight major sedimentary facies have been described involving the succession of coastal, aeolian, colluvial and alluvial environments. Carbonate sandstones, breccias, conglomerates and fine-grained deposits are the main component of these sequences. OSL dating of aeolian levels indicate that their deposition took place during the Late Pleistocene, establishing a paleoclimatic evolution of Balearic coastal areas during the last 125 ka. The sedimentological and chronological analysis of these deposits allows reconstructing the coastal environmental changes during the Late Pleistocene at the Balearic archipelago. Keywords: Alluvial sedimentation, eolian sedimentation, alluvial-eolian interference, sea level, Late Pleistocene, Balearic Islands.

  12. Some problems on the studies of the late Pleistocene human evolution and formation of modern human populations

    LIU Wu

    2006-01-01

    For the past two decades, studies and debates on the modern human origins around the world have attracted attentions to the late Pleistocene human evolution and formation of modern human populations, and some controversial hypotheses and problems have been proposed. In the present paper, some problems on the late Pleistocene human evolution, and the formation and differentiations of modern human populations in China are studied with a brief description and comments on the research advances in this field.

  13. Distribution of late Pleistocene ice-rich syngenetic permafrost of the Yedoma Suite in east and central Siberia, Russia

    Grosse, Guido; Robinson, Joel E.; Bryant, Robin; Taylor, Maxwell D.; Harper, William; DeMasi, Amy; Kyker-Snowman, Emily; Veremeeva, Alexandra; Schirrmeister, Lutz; Harden, Jennifer

    2013-01-01

    This digital database is the product of collaboration between the U.S. Geological Survey, the Geophysical Institute at the University of Alaska, Fairbanks; the Los Altos Hills Foothill College GeoSpatial Technology Certificate Program; the Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany; and the Institute of Physical Chemical and Biological Problems in Soil Science of the Russian Academy of Sciences. The primary goal for creating this digital database is to enhance current estimates of soil organic carbon stored in deep permafrost, in particular the late Pleistocene syngenetic ice-rich permafrost deposits of the Yedoma Suite. Previous studies estimated that Yedoma deposits cover about 1 million square kilometers of a large region in central and eastern Siberia, but these estimates generally are based on maps with scales smaller than 1:10,000,000. Taking into account this large area, it was estimated that Yedoma may store as much as 500 petagrams of soil organic carbon, a large part of which is vulnerable to thaw and mobilization from thermokarst and erosion. To refine assessments of the spatial distribution of Yedoma deposits, we digitized 11 Russian Quaternary geologic maps. Our study focused on extracting geologic units interpreted by us as late Pleistocene ice-rich syngenetic Yedoma deposits based on lithology, ground ice conditions, stratigraphy, and geomorphological and spatial association. These Yedoma units then were merged into a single data layer across map tiles. The spatial database provides a useful update of the spatial distribution of this deposit for an approximately 2.32 million square kilometers land area in Siberia that will (1) serve as a core database for future refinements of Yedoma distribution in additional regions, and (2) provide a starting point to revise the size of deep but thaw-vulnerable permafrost carbon pools in the Arctic based on surface geology and the distribution of cryolithofacies types at high spatial

  14. Deciphering Late-Pleistocence landscape evolution: linking proxies by combining pedo-stratigraphy and luminescence dating

    Kreutzer, Sebastian; Meszner, Sascha; Faust, Dominik; Fuchs, Markus

    2014-05-01

    Interpreting former landscape evolution asks for understanding the processes that sculpt such landforms by means of deciphering complex systems. For reconstructing terrestrial Quaternary environments based on loess archives this might be considered, at least, as a three step process: (1) Identifying valuable records in appropriate morphological positions in a previously defined research area, (2) analysing the profiles by field work and laboratory methods and finally (3) linking the previously considered pseudo-isolated systems to set up a comprehensive picture. Especially the first and the last step might bring some pitfalls, as it is tempting to specify single records as pseudo-isolated, closed systems. They might be, with regard to their preservation in their specific morphological position, but in fact they are part of a complex, open system. Between 2008 and 2013, Late-Pleistocene loess archives in Saxony have been intensively investigated by field and laboratory methods. Linking pedo- and luminescence dating based chronostratigraphies, a composite profile for the entire Saxonian Loess Region has been established. With this, at least, two-fold approach we tried to avoid misinterpretations that might appear when focussing on one standard profile in an open morphological system. Our contribution focuses on this multi-proxy approach to decipher the Late-Pleistocene landscape evolution in the Saxonian Loess Region. Highlighting the challenges and advantages of combining different methods, we believe that (1) this multi-proxy approach is without alternative, (2) the combination of different profiles may simplify the more complex reality, but it may be a useful generalisation to understand and reveal the stratigraphical significance of the landscape evolution in this region.

  15. Argon geochronology of late Pleistocene to Holocene Westdahl volcano, Unimak Island, Alaska

    Calvert, Andrew T.; Moore, Richard B.; McGimsey, Robert G.

    2005-01-01

    High-precision 40Ar/39Ar geochronology of selected lavas from Westdahl Volcano places time constraints on several key prehistoric eruptive phases of this large active volcano. A dike cutting old pyroclastic-flow and associated lahar deposits from a precursor volcano yields an age of 1,654+/-11 k.y., dating this precursor volcano as older than early Pleistocene. A total of 11 geographically distributed lavas with ages ranging from 47+/-14 to 127+/-2 k.y. date construction of the Westdahl volcanic center. Lava flows cut by an apparent caldera-rim structure yielded ages of 81+/-5 and 121+/-8 k.y., placing a maximum date of 81 ka on caldera formation. Late Pleistocene and Holocene lavas fill the caldera, but most of them are obscured by the large summit icecap.

  16. People of the ancient rainforest: late Pleistocene foragers at the Batadomba-lena rockshelter, Sri Lanka.

    Perera, Nimal; Kourampas, Nikos; Simpson, Ian A; Deraniyagala, Siran U; Bulbeck, David; Kamminga, Johan; Perera, Jude; Fuller, Dorian Q; Szabó, Katherine; Oliveira, Nuno V

    2011-09-01

    Batadomba-lena, a rockshelter in the rainforest of southwestern Sri Lanka, has yielded some of the earliest evidence of Homo sapiens in South Asia. H. sapiens foragers were present at Batadomba-lena from ca. 36,000 cal BP to the terminal Pleistocene and Holocene. Human occupation was sporadic before the global Last Glacial Maximum (LGM). Batadomba-lena's Late Pleistocene inhabitants foraged for a broad spectrum of plant and mainly arboreal animal resources (monkeys, squirrels and abundant rainforest snails), derived from a landscape that retained equatorial rainforest cover through periods of pronounced regional aridity during the LGM. Juxtaposed hearths, palaeofloors with habitation debris, postholes, excavated pits, and animal and plant remains, including abundant Canarium nutshells, reflect intensive habitation of the rockshelter in times of monsoon intensification and biome reorganisation after ca. 16,000 cal BP. This period corresponds with further broadening of the economic spectrum, evidenced though increased contribution of squirrels, freshwater snails and Canarium nuts in the diet of the rockshelter occupants. Microliths are more abundant and morphologically diverse in the earliest, pre-LGM layer and decline markedly during intensified rockshelter use on the wane of the LGM. We propose that changing toolkits and subsistence base reflect changing foraging practices, from shorter-lived visits of highly mobile foraging bands in the period before the LGM, to intensified use of Batadomba-lena and intense foraging for diverse resources around the site during and, especially, following the LGM. Traces of ochre, marine shell beads and other objects from an 80 km-distant shore, and, possibly burials reflect symbolic practices from the outset of human presence at the rockshelter. Evidence for differentiated use of space (individual hearths, possible habitation structures) is present in LGM and terminal Pleistocene layers. The record of Batadomba-lena demonstrates

  17. Progress in integrated Late Triassic carbon isotopic stratigraphy of the Northern Calcareous Alps

    Richoz, Sylvain; Krystyn, Leopold; Lein, Richard

    2015-04-01

    During the Late Triassic, despite new important originations a general decline in biodiversity was marked by a series of steps between the Carnian and the Rhaetian, with the T-J boundary event as final strike. The Reingraben Event and the Julian-Tuvalian boundary are two first massive turnovers; the Carnian-Norian boundary records a major vertebrate turnover, the early to middle Norian boundary comes up with a turnover in both the reefal and pelagic fauna and the most dramatic loss (70%) in biodiversity among Late Triassic molluscs. Around the Norian-Rhaetian boundary, the pelagic fauna of higher trophic level starts declining, whereas the reefs experience a blooming time. A refined stratigraphy and a construction of a well-calibrated carbon isotope reference curve are necessary to decipher between gradual environmental changes and abrupt or even catastrophic events during the Late Triassic. Improvement in the Upper Triassic d13Ccarb curve shows that after a gentle increase until the base of the Carnian, the early Carnian records three negative excursions of 2 to 3‰ amplitude. The two first excursions rebound to previous values, whereas the third negative excursion, at the Julian-Tuvalian boundary, is followed by a positive excursion up to +5‰. The remaining Upper Carnian displays stabile values around 2‰. The Carnian-Norian boundary interval is marked by a minor increase of less than 1‰. The Early to Middle Norian crisis is marked by a turning point from Early Norian slowly increasing carbon isotope values (up to 3.5‰) to gradually decreasing ones until 1.8‰ at the base of the Rhaetian. This Norian decrease display two accelerated steps, one in the middle Norian and the other one just after the Norian-Rhaetian Boundary. This last 1‰ decrease corresponds however to an important change in lithology. The values show then a small increase during the early Rhaetian, with a maximum in the middle Rhaetian (at 2.4‰). The isotopic record remains constant

  18. Response of methanogenic archaea to Late Pleistocene and Holocene climate changes in the Siberian Arctic

    Bischoff, Juliane; Mangelsdorf, Kai; Gattinger, Andreas; Schloter, Michael; Kurchatova, Anna N.; Herzschuh, Ulrike; Wagner, Dirk

    2013-04-01

    order to investigate the link between the methane dynamics in permafrost deposits and climate changes in the past, we studied the abundance, composition, and methane production of methanogenic communities in Late Pleistocene and Holocene sediments of the Siberian Arctic. We detected intervals of increased methane concentrations in Late Pleistocene and Holocene deposits along a 42 ka old permafrost sequence from Kurungnakh Island in the Lena Delta (northeast Siberia). Increased amounts of archaeal life markers (intact phospholipid ethers) and a high variety in genetic fingerprints detected by 16S ribosomal ribonucleic acid gene analyses of methanogenic archaea suggest presently living and presumably active methanogenic archaea in distinct layers predominantly in Holocene deposits, but also in deep frozen ground at 17 m depth. Potential methanogenic activity was confirmed by incubation experiments. By comparing methane concentrations, microbial incubation experiments, gene analysis of methanogens, and microbial life markers (intact phospholipid esters and ethers) to already partly degraded membrane lipids, such as archaeol and isoprenoid glycerol dialkyl glycerol tetraethers, we demonstrated that archaeol likely represents a signal of past methanogenic archaea. The archaeol signal was used to reconstruct the response of methanogenic communities to past temperature changes in the Siberian Arctic, and the data suggest higher methane emissions occurred during warm periods, particularly during an interval in the Late Pleistocene and during the Holocene. This new data on present and past methanogenic communities in the Siberian terrestrial permafrost imply that these microorganisms will respond to the predicted future temperature rise in the Arctic with increasing methane production, as demonstrated in previous warmer periods.

  19. Testing the correlation of fragmented pollen records of the middle and late Pleistocene temperate stages

    Kuneš, Petr; Odgaard, Bent Vad

    Europe provide good chronologies and thus enable a biostratigraphic definition of at least younger MIS. In Northern Europe, however, the fragmentary character of the records and the weaknesses of absolute dating prevent good age estimates. Therefore, age-determination of the majority of fragmentary...... records depends on site-to-site correlations. This comparison has often been performed on a visual basis, lacking clearly defined protocols and statements of underlying assumptions. Here I test the correlation of well and poorly known pollen records of the middle- and late-Pleistocene temperate stages...

  20. Uranium Series Chronology of the Late Pleistocene Basalt from the Longgang Volcanoes, Jilin Province

    YU Fusheng; HAN Song; MA Zhibang; XIE Ruijie

    2005-01-01

    The Longgang volcanic cluster located in Jilin Province belongs to one of the active volcanic regions in northeast China, and has been active in modem times. In view of the multiple eruptions in history, it is very important to determine the age of each eruption for evaluating the volcanic hazards. Two alkaline basalt samples taken from Dayizishan and Diaoshuihu were analyzed with the U-series component dating after magnetic separation. The ages of the two samples are (71±9) ka and (106±13) ka B.P., respectively. These data indicate that there existed intensive eruption activities during the late Pleistocene.

  1. Late Pleistocene to Holocene environmental changes from ¿13C determinations in soils at Teotihuacan, Mexico

    E. Lounejeva Baturina; P. Morales Puente; H. V. Cabadas Báez; E. Cienfuegos Alvarado; S. Sedov; E. Vallejo Gómez; E. Solleiro Rebolledo

    2006-01-01

    Stable carbon isotopic signature ( #948;13C) of soil organic matter (SOM) is used as a high-spatial resolution tool to infer environmental changes during late Pleistocene to Present in the Teotihuacan valley, Mexico. Interpretation was based on climatic preferences of C3, CAM and C4 plant groups. #948;13C values of modern plant types are clearly distinguished. C3 plants display values around –27‰, while C4 and CAM plants have values around––13‰. Data from soil profiles range from -25.7 to -1...

  2. Magnetic properties of greigite in the Late Pleistocene sediments of the North Caspian

    Bol'shakov, V. A.; Dolotov, A. V.

    2012-06-01

    The results of magnetic and X-ray studies of the magnetic extracts separated from highly magnetically susceptible horizons of the Late Pleistocene sediments from the North Caspian Basin are presented. Greigite is shown to be the major carrier of magnetic properties in these horizons. Its coercive parameters are characteristic of the predominantly single-domain state of magnetic grains. It is found that the Curie point of greigite is at least 460°C, while the specific magnetization of pure greigite is half the saturation magnetization of magnetite.

  3. The first radiation dates of syngenetic Late Pleistocene ice-wedges

    Direct radiocarbon dating of organic mater extracted directly from ice wedges of the Late Pleistocene wedges of Siberia using the accelerating mass spectrometry was carried out. It is shown that the ice wedges opened in the cross section base at a height from 0 to +1 m started their formation about 21 thousand years ago. The rate of the wedges vertical growth in the course of 21-14.7 thousand of years. Subhorizontal age stratification of the ice-wedges formed by consecutive penetration of thawing ice water along with accumulation of precipitate on the surface, was confirmed

  4. First direct dating of Late Pleistocene ice-wedges by AMS

    Vasil'chuk, YK; Van Der Plicht, J.; Jungner, H.; Sonninen, E; Vasil'chuk, AC; Vasil'chuk, Yurij K.; Vasil'chuk, Alla C.

    2000-01-01

    We present the first direct dating by C-14-accelerator mass spectrometry of three Late Pleistocene syngenetic ice-wedges from the Seyaha cross-section. They are representative of permafrost with multistage ice-wedges from the North of Western Siberia. The most important result is the clear vertical age stratification of the ice, i.e. the old ice is located beneath the young. This shows that a timescale can be assigned to these ice-wedges penetrating down into the permafrost. The age of the ic...

  5. AMS-dating of Late Pleistocene and Holocene syngenetic ice-wedges

    We discuss the 14C dating (both conventional and AMS) of Siberian permafrost sediments and ice-wedge ice. Direct dating of Late Pleistocene and Holocene syngenetic ice-wedges was done on organic material included in the ice. The time of ice formation (in 14C years) is 21,000-14,000 BP for Seyaha, and 7100 BP for Shchuch'ya. The AMS dates show that the ice-wedges stratification is normal, i.e., the older ice is located below the younger. The 14C dates yield for the first time a timescale (in 14C years) for paleoclimatic indicators (oxygen and hydrogen isotope ratios from the ice)

  6. Magnetic Properties of Bermuda Rise Sediments Controlled by Glacial Cycles During the Late Pleistocene

    Roud, S.

    2015-12-01

    Sediments from ODP site 1063 (Bermuda Rise, North Atlantic) contain a high-resolution record of geomagnetic field behavior during the Brunhes Chron. We present rock magnetic data of the upper 160 mcd (Bermuda rise sediments deposited during the late Pleistocene. Hematite concentration is interpreted to reflect primary terrigenous input that is likely derived from the Canadian Maritime Provinces. A close correlation between HIRM and magnetic foliation suggests that changes in sediment composition (terrigenous vs. marine biogenic) were accompanied by changes in the depositional processes at the site.

  7. First record of Procyon cancrivorus (G. Cuvier, 1798) (Carnivora, Procyonidae) in stratigraphic context in the Late Pleistocene of Brazil

    Rodriguez, Sergio G.; Soibelzon, Leopoldo H.; Rodrigues, Shirlley; Morgan, Cecilia C.; Bernardes, Camila; Avilla, Leonardo; Lynch, Eric

    2013-08-01

    Although five genera of procyonids are currently present in South America, only two of the extant genera, Procyon and Nasua are represented in the South American fossil record. A recent discovery of a procyonid lower second molar in Late Pleistocene deposits of Aurora do Tocantins, northern Brazil, offers potential to further our understanding of the stratigraphic and temporal range of South American fossil procyonids. We use geometric morphometric analysis of two-dimensional landmarks and semilandmarks to explore morphological variation in the lower second molars of extant Procyon lotor and Procyon cancrivorus and multivariate methods to support the identification of the Pleistocene specimen as P. cancrivorus. This material represents the second fossil record of P. cancrivorus in South America Procyonids entered South America in two phases: the first comprising by Cyonasua and Chapadmalania during the Late Miocene, and the other recent genera, beginning in the Late Pleistocene. These Late Miocene procyonids were more carnivorous than Late Pleistocene-Recent omnivorous taxa and possible went extinct due to competition with other placental carnivorans that entered South America and diversified during the latest Pliocene-Early Pleistocene.

  8. Phylogeography of the Alcippe morrisonia (Aves: Timaliidae: long population history beyond late Pleistocene glaciations

    Li Shouhsien

    2009-06-01

    Full Text Available Abstract Background The role of Pleistocene glacial oscillations in current biodiversity and distribution patterns varies with latitude, physical topology and population life history and has long been a topic of discussion. However, there had been little phylogeographical research in south China, where the geophysical complexity is associated with great biodiversity. A bird endemic in Southeast Asia, the Grey-cheeked Fulvetta, Alcippe morrisonia, has been reported to show deep genetic divergences among its seven subspecies. In the present study, we investigated the phylogeography of A. morrisonia to explore its population structure and evolutionary history, in order to gain insight into the effect of geological events on the speciation and diversity of birds endemic in south China. Results Mitochondrial genes cytochrome b (Cytb and cytochrome c oxidase I (COI were represented by 1236 nucleotide sites from 151 individuals from 29 localities. Phylogenetic analysis showed seven monophyletic clades congruent with the geographically separated groups, which were identified as major sources of molecular variance (90.92% by AMOVA. TCS analysis revealed four disconnected networks, and that no haplotype was shared among the geographical groups. The common ancestor of these populations was dated to 11.6 Mya and several divergence events were estimated along the population evolutionary history. Isolation by distance was inferred by NCPA to be responsible for the current intra-population genetic pattern and gene flow among geographical groups was interrupted. A late Pleistocene demographic expansion was detected in the eastern geographical groups, while the expansion time (0.2–0.4 Mya was earlier than the Last Glacial Maximum. Conclusion It is proposed that the complicated topology preserves high genetic diversity and ancient lineages for geographical groups of A. morrisonia in China mainland and its two major islands, and restricts gene exchange during

  9. Huanglong Cave, a new late Pleistocene hominid site in Hubei Province, China

    WU Xianzhu; LIU Wu; GAO Xing; YIN Gongming

    2006-01-01

    For the past 20 years the modern human origins debate has received a significant amount of attention in paleoanthropological research. Primarily supported by the evidence of earlier dates of anatomically modern human fossils and genetic studies, the "Out of Africa" hypothesis is based on the belief that the ancestor of all modern humans, including modern Chinese, came from Africa. The opposite hypothesis "Mutiregional evolution" proposes that continuous evolution occurred on a regional scale, for which human paleontology offers strong support. However, due to the paucity of hominid fossils in China between 100 and 50 ka, support to the latter hypothesis is currently weak. This is a report here of five human fossil teeth, and associated stone tools and mammal fossils from a newly discovered cave site, Huanglong Cave, located in Yunxi County,Hubei Province, China. Preliminary studies indicate:(1) the morphological features of the human fossils resemble those of late Pleistocene human fossils from China; (2) the stone tools display patterns of both the southern and northern Paleolithic cultures of China; (3) the mammal fossils represent the "Ailuropoda-Stegodon" faunal unit which lived in southern China throughout the Pleistocene. ESR and U-series dating on animal teeth and a stalagmite derived from the same layer as the human teeth indicate two possible ages: 103±1.6 ka and 44±12.5 ka. In addition to other evidence presented here, it is believed that hominid occupation of the cave was likely around 100 ka. If this age is further substantiated, Huanglong Cave will be the first late Pleistocene hominid fossil site in China where anatomically modern humans lived about 100 ka. The human fossils and other related materials from Huanglong Cave will provide important information for research on the origin of modern Chinese.

  10. A chronology of Late-Pleistocene permafrost events in southern New Jersey, eastern USA

    French, H.M.; Demitroff, M.; Forman, S.L.; Newell, W.L.

    2007-01-01

    Frost fissures, filled with wind-abraded sand and mineral soil, and numerous small-scale non-diastrophic deformations, occur in the near-surface sediments of the Pine Barrens of southern New Jersey. The fissures are the result of thermal-contraction cracking and indicate the previous existence of either permafrost or seasonally-frozen ground. The deformations reflect thermokarst activity that occurred when permafrost degraded, icy layers melted and density-controlled mass displacements occurred in water-saturated sediments. Slopes and surficial materials of the area reflect these cold-climate conditions. Optically-stimulated luminescence permits construction of a tentative Late-Pleistocene permafrost chronology. This indicates Illinoian, Early-Wisconsinan and Late-Wisconsinan episodes of permafrost and/or deep seasonal frost and a Middle-Wisconsinan thermokarst event. Copyright ?? 2007 John Wiley & Sons, Ltd.

  11. A Pathological Late Pleistocene canid from San Sidero (Italy): implications for social- and feeding-behaviour

    Iurino, Dawid Adam; Fico, Rosario; Petrucci, Mauro; Sardella, Raffaele

    2013-03-01

    Evidence of diseases on vertebrate fossil bones can provide detailed information on many aspects of extinct animals. This study focused on pathological craniodental remains (left maxilla and dentary) referred to the canid Cuon alpinus unearthed from a Late Pleistocene karst filling deposit at San Sidero (Apulia, southern Italy). These fossils show clear evidence of a chronic periodontitis that caused the animal's death. Clinical diagnosis of the disease and the timing of its development have been defined on the basis of a veterinary odontostomatology approach, in addition to radiographic and tomographic techniques. From the initiation of the infection until death, a time span of at least 6 months occurred, and three main steps have been defined: (1) the bacterial infections of the buccal cavity turning into severe periodontitis, (2) the fracture of the lower carnassial and (3) the loss of teeth due to the worsening infection that deformed and/or eroded maxillary and mandibular bones and enlarged alveoli. The analysis of the palaeopathology also provides information about the biomechanics of the bite, on the feeding behaviour and on the relationships of injured members in a pack of Late Pleistocene canids.

  12. Rodent burrows in late Pleistocene paleosols at Korean Palaeolithic sites and their implications for paleoclimate changes

    Lim, H.; Park, S.; Lee, J.; Lee, Y.

    2013-12-01

    Rodent burrows are commonly found at many Paleolithic archaeological sites in Korea. They are nearly straight in horizontal view and gently inclined in lateral view. Burrow diameters are mostly 7 - 10cm, and burrow length may reach a few meters. Vertical penetration depths are generally about 1 m from the surface, and the thickness of the burrow-bearing layer is about 1-2 m. Although no remains (bones, teeth, claws, and coprolites) were found within burrows, they are interpreted to have been produced by rodent-like mammals (probably ground squirrels) based on the size and architecture. According to the previous study, the age of these burrows was constrained to be between ca. 40,000 and 25,000 yr BP by tephrochronology, radiocarbon and optically stimulated luminescence dating results (Lim et al., 2007). However, little is known about the reason why these burrows have disappeared after late Pleistocene time. For this question, two explanations can be considered: extinction or migration. Since same kinds of burrows are still found in the high-latitude regions, such as Mongolia and North America, the possibility of extinction can be ruled out. Therefore, migration seems to be the most likely explanation. Our results show that the destruction of habitat caused by climate change during this period is the main reason for the northward migration of burrowing animals. This study suggests that rodent burrows found in the late Pleistocene paleosols can provide useful information on paleoclimate and paleoenvironmental changes.

  13. The diversity and biogeography of late Pleistocene birds from the lowland Neotropics

    Steadman, David W.; Oswald, Jessica A.; Rincón, Ascanio D.

    2015-05-01

    The Neotropical lowlands sustain the world's richest bird communities, yet little that we know about their history is based on paleontology. Fossils afford a way to investigate distributional shifts in individual species, and thus improve our understanding of long-term change in Neotropical bird communities. We report a species-rich avian fossil sample from a late Pleistocene tar seep (Mene de Inciarte) in northwestern Venezuela. A mere 175 identified fossils from Mene de Inciarte represent 73 species of birds, among which six are extinct, and eight others no longer occur within 100 km. These 14 species consist mainly of ducks (Anatidae), snipe (Scolopacidae), vultures/condors (Vulturidae), hawks/eagles (Accipitridae), and blackbirds (Icteridae). Neotropical bird communities were richer in the late Pleistocene than today; their considerable extinction may be related to collapse of the large mammal fauna at that time. The species assemblage at Mene de Inciarte suggests that biogeographic patterns, even at continental scales, have been remarkably labile over short geological time frames. Mene de Inciarte is but one of 300 + tar seeps in Venezuela, only two of which have been explored for fossils. We may be on the cusp of an exciting new era of avian paleontology in the Neotropics.

  14. Mastodon herbivory in mid-latitude late-Pleistocene boreal forests of eastern North America

    Teale, Chelsea L.; Miller, Norton G.

    2012-07-01

    Skeletal remains of the extinct American mastodon have often been found with deposits of short, decorticated twigs intermixed with plant fragments presumed to be gastrointestinal or fecal material. If such deposits are digesta, paleobotanical evidence may be used to analyze mastodon foraging strategy, with implications for assessing habitat selection, ecological roles, and response to environmental change. To identify components of mastodon diet in mid-latitude late-Pleistocene boreall forests of eastern North America, plant macrofossils and pollen from a molar socket (Hyde Park site, New York) were compared with dispersed deposits associated with skeletal remains (Hiscock and Chemung sites, New York). Similar macrofossil condition and twig morphology among samples, but difference from a modern boreal fen analog, confirmed the deposits were digesta. Comparison of twigs with material from other paleontological sites and modern elephants suggested dimensions generally indicative of digesta. Picea formed the bulk of each sample but Pinus may have been locally important. Wintertime browsing of Salix and Populus, and springtime consumption of Alnus, were indicated. Evidence for Cyperaceae, Gramineae, and Compositae was ambiguous. If conifers, broadleaf trees, shrubs, and herbs were necessary to fulfill dietary requirements, mastodons would have been nutritionally stressed by rapid late-Pleistocene decrease in vegetational diversity.

  15. Seismic stratigraphy of Pliocene-Pleistocene deposits, continental slope-upper Mississippi Fan, northern Gulf of Mexico

    Walters, R.D.; Buffler, R.T.

    1985-02-01

    Regional multichannel seismic data are used to develop a seismic stratigraphic framework for the continental slope-upper Mississippi fan region in the northern Gulf of Mexico. In the Mississippi canyon area, upper Pliocene and Pleistocene paleontologic zones from wells provide age control for major seismic sequence boundaries. A major unconformity and high-amplitude reflector identified as the base of Pleistocene represents a break in sedimentation and probably marks onset of fan deposition. This unconformity and others within the Pleistocene define sequences showing cyclic patterns of deposition, which are related to Pleistocene sea level changes and salt mobilization. Interpretation of seismic facies and their relationships to sea level changes, glaciations, and salt movement results in a model for the depositional history of the Mississippi fan from the canyon area to the deep-water part of the fan. Low-amplitude, chaotic, onlapping facies are interpreted as slump or debris-flow deposits associated with canyon cutting by retrogressive failure and initiation of large-scale mass movement due to a relative lowering of sea level. High-amplitude, parallel, continuous reflectors at sequence boundaries represent pelagic and hemipelagic sediments associated with a succeeding rise in relative sea level. In the shelf-upper slope area, isolated salt diapirs influence sedimentation on a localized scale. In the lower slope to upper fan, most Pleistocenen section is extensively disrupted by parallel sets of salt ridges that result from differential loading of fan sediments. Shifting depocenters and migratory channel systems funnel sediment through this area onto the lower fan. Salt wedges in the eastern study area appear to represent detached salt masses isolated within the Pleistocene section.

  16. Late Stone Age human remains from Ishango (Democratic Republic of Congo): New insights on Late Pleistocene modern human diversity in Africa.

    Crevecoeur, I; Brooks, A; Ribot, I; Cornelissen, E; Semal, P

    2016-07-01

    Although questions of modern human origins and dispersal are subject to intense research within and outside Africa, the processes of modern human diversification during the Late Pleistocene are most often discussed within the context of recent human genetic data. This situation is due largely to the dearth of human fossil remains dating to the final Pleistocene in Africa and their almost total absence from West and Central Africa, thus limiting our perception of modern human diversification within Africa before the Holocene. Here, we present a morphometric comparative analysis of the earliest Late Pleistocene modern human remains from the Central African site of Ishango in the Democratic Republic of Congo. The early Late Stone Age layer (eLSA) of this site, dated to the Last Glacial Maximum (25-20 Ky), contains more than one hundred fragmentary human remains. The exceptional associated archaeological context suggests these remains derived from a community of hunter-fisher-gatherers exhibiting complex social and cognitive behaviors including substantial reliance on aquatic resources, development of fishing technology, possible mathematical notations and repetitive use of space, likely on a seasonal basis. Comparisons with large samples of Late Pleistocene and early Holocene modern human fossils from Africa and Eurasia show that the Ishango human remains exhibit distinctive characteristics and a higher phenotypic diversity in contrast to recent African populations. In many aspects, as is true for the inner ear conformation, these eLSA human remains have more affinities with Middle to early Late Pleistocene fossils worldwide than with extant local African populations. In addition, cross-sectional geometric properties of the long bones are consistent with archaeological evidence suggesting reduced terrestrial mobility resulting from greater investment in and use of aquatic resources. Our results on the Ishango human remains provide insights into past African modern

  17. Environmental evolutions of the Alzette valley (Grand Duchy of Luxembourg) since Late Pleistocene

    Naton, H.-G.; Ruffaldi, P.; Meyrick, R.; Maquil, R.; Colbach, R.; Kausch, B.; Baes, R.; Stead, A.; Le Brun-Ricalens, F.; Brou, L.; Schoellen, A.

    2009-04-01

    The Alzette River rises within France, approximately 4 km south of the French-Luxembourg border, and has a total length of 73 kilometres before joining the Sauer which is a left-bank tributary of the Moselle River. During the construction of the "Nordstrooss" motorway (going north from Luxembourg city towards Ettelbruck) a viaduct was built that crosses the wide alluvial plain (about 1 km) of the Alzette River valley near Lorentzweiler. A lot of drillings were also made for geotechnical purposes by the Geological survey of Luxembourg (SGL). The drillings were able to provide informations about the sediments preserved in the Alzette River valley floor. This information has allowed the construction of a cross-profile through the valley showing the stratigraphy of the quaternary deposits, and illustrating that it was the result of a rather complex evolution (aggradation and incision periods leading to terraces formation, input of slope deposits at the valley margins, possible eolian input, …). A multidisciplinary research project thus started, aiming to reconstruct the paleoenvironment of the Alzette region during the late Pleistocene and Holocene periods. The drilling results make it possible to reconstruct the geometry of the quaternary sedimentary units of the Alzette valley. Three stepped alluvial units are recognized along the cross profile: the lower one (Az0) corresponds with the maximal incision of the Alzette. It is preserved in the western part of the floodplain, with base being located at about 212 m a.s.l.. In the eastern part of the valley the contact between the fluvial deposits and the substratum is located at about 215 m a.s.l.: these deposits may also be allocated to a lower terrace Az1 (relative height : +3 m). A third alluvial unit Az2 was recognized in two drillings, with bedrock located at about 224 m a.s.l. (+12 m). The channel migration in the valley and the assumed meandering dynamics (suggested by the weakness of the longitudinal slope) led

  18. A late Pleistocene steppe bison ( Bison priscus) partial carcass from Tsiigehtchic, Northwest Territories, Canada

    Zazula, Grant D.; MacKay, Glen; Andrews, Thomas D.; Shapiro, Beth; Letts, Brandon; Brock, Fiona

    2009-12-01

    A partial steppe bison ( Bison priscus) carcass was recovered at Tsiigehtchic, near the confluence of the Arctic Red and Mackenzie Rivers, Northwest Territories, Canada in September of 2007. The carcass includes a complete cranium with horn cores and sheaths, several complete post-cranial elements (many of which have some mummified soft tissue), intestines and a large piece of hide. A piece of metacarpal bone was subsampled and yielded an AMS radiocarbon age of 11,830 ± 45 14C yr BP (OxA-18549). Mitochondrial DNA sequenced from a hair sample confirms that Tsiigehtchic steppe bison ( Bison priscus) did not belong to the lineage that eventually gave rise to modern bison ( Bison bison). This is the first radiocarbon dated Bison priscus in the Mackenzie River valley, and to our knowledge, the first reported Pleistocene mammal soft tissue remains from the glaciated regions of northern Canada. Investigation of the recovery site indicates that the steppe bison was released from the permafrost during a landslide within unconsolidated glacial outwash gravel. These data indicate that the lower Mackenzie River valley was ice free and inhabited by steppe bison by ˜11,800 14C years ago. This date is important for the deglacial chronology of the Laurentide Ice Sheet and the opening of the northern portal to the Ice Free Corridor. The presence of steppe bison raises further potential for the discovery of more late Pleistocene fauna, and possibly archaeological evidence, in the region.

  19. Relationship between Late Pleistocene sea-level variations, carbonate platform morphology and aragonite production (Maldives, Indian Ocean)

    Paul, A.; Reijmer, J.J.G.; Fürstenau, J.; Kinkel, Hanno; Betzler, C.

    2012-01-01

    A piston core from the Maldives carbonate platform was investigated for carbonate mineralogy, grain-size distributions, calcium carbonate content and organic carbon. The sedimentary record was linked to Late Pleistocene sea-level variations, using an age model based on oxygen isotopes obtained from...... planktonic foramanifera, nannofossil biostratigraphy and C age determinations. The correlation between the sedimentary record and Late Pleistocene sea-level showed that variations in aragonite and mud during the past 150000years were clearly related to flooding and sea floor exposure of the main lagoons of...... show that sediments on the Maldives carbonate platform contain a continuous record of Pleistocene sea-level variations. These sediments may, therefore, contribute to a better understanding of regional and even global sea-level changes, and yield new insights into the interplay between ocean currents...

  20. Nothrotherium CF.N.Maquinense (xenarthra, tardigrada) in the sopas formation (late pleistocene of Uruguay)

    The quaternary continental Sopas Formation of Uruguay shows a faunal moisture which joins typical representatives of the pampean region with components of northern origin. Remains assigned to the Family Nothrotheriidae were mentioned for this unit on the basis of very fragmented material. The presence of the genus Nothrotherium in the Sopas Formation is confirmed, the finding of the species Nothrotherium. cf. N. maquinense is communicated, and the corresponding remain is described, a right mandibular ramus. N. maquinense was distributed in the territory today named Brazil during the Late Pleistocene – Early Holocene lapse, in a diverse tropical climate which favored the development of savanna vegetation. The chronology and environments inferred from this finding are not contradictory with the previous proposals for the Sopas Formation

  1. Environmentally controlled succession in a late Pleistocene coral reef (Sinai, Egypt)

    Mewis, H.; Kiessling, W.

    2013-03-01

    The concept of ecological succession has been frequently applied in the study of ancient reefs. Whereas Paleozoic and Mesozoic reefs are commonly thought to reveal an autogenic primary—climax zonation, patterns in Neogene and Quaternary reefs are much more diverse. Here, we describe a well-preserved late Pleistocene coral reef from Dahab on Sinai Peninsula (Egypt), which shows a distinct zonation that resembles an ecological succession. In contrast to classical examples of ecological successions, species composition, paleoenvironmental conditions, and coral biodiversity of the Dahab reef indicate an allogenic, sea-level controlled community change, from marginal marine to reef slope and back reef. A review of the literature confirms that autogenic, short-term successions are virtually absent in Quaternary reefs. We predict that long generation times of corals make it unlikely that classical autogenic successions develop in reefs at all, unless environmental conditions are unusually stable.

  2. Late Pleistocene lithostratigraphy and sequences in the southwestern Mesopotamia (Argentina): Evidences of the last interglacial stage

    Ernesto, Brunetto; Soledad, Ferrero Brenda; Ignacio, Noriega Jorge

    2015-03-01

    The aim of this paper is to show the stratigraphic record of the Late Pleistocene corresponding to the distal region of the Paraná River basin. It displays sedimentological, paleontological and geochronological evidences that characterise the last interglacial-glacial cycle. In particular, strong environmental records are shown for the Last Interglacial Stage (LIS). Salto Ander Egg Formation (SAEF) is defined as a new lithostratigraphic unit representative of the Late Pleistocene in southwestern Mesopotamia. This unit is formed of complex fluvial deposits, which contains a heterogeneous collection of sub-environments, of ages ranging from 120 to 60 ky BP. The clast-supported gravel facies containing sparse boulders indicate high flow during a humid climate. The large and middle-scale architectures of fluvial sedimentary bodies evidence the relationship between the sediment accommodation and the sea level oscillations. Three sub-sequences identified in the succession suggest a transgressive trend during the MIS5e, a highstand stage in MIS5c, and a minor transgressive cycle during MIS3. A Brazilian faunal association collected at the bottom of the sequence and sedimentological interpretations display wet and warm climatic conditions, typical of tropical or subtropical environments. Such environmental conditions are characteristic of the maximum of the last interglacial stage (MIS5e) and show a signal stronger than the signal of the current interglacial stage. All these data show a direct correlation between the increases of paleodischarges and the elevation of the sea level. The whole sequence is completed with transitional swampy deposits, accumulated probably during the MIS3/MIS2 transition, and the typical loess of the Tezanos Pinto Formation, mantled during the Last Maximum Glacial.

  3. Late Pleistocene and Holocene environmental history of the Iguala Valley, Central Balsas Watershed of Mexico.

    Piperno, D R; Moreno, J E; Iriarte, J; Holst, I; Lachniet, M; Jones, J G; Ranere, A J; Castanzo, R

    2007-07-17

    The origin of agriculture was a signal development in human affairs and as such has occupied the attention of scholars from the natural and social sciences for well over a century. Historical studies of climate and vegetation are closely associated with crop plant evolution because they can reveal the ecological contexts of plant domestication together with the antiquity and effects of agricultural practices on the environment. In this article, we present paleoecological evidence from three lakes and a swamp located in the Central Balsas watershed of tropical southwestern Mexico that date from 14,000 B.P. to the modern era. [Dates expressed in B.P. years are radiocarbon ages. Calibrated (calendar) ages, expressed as cal B.P., are provided for dates in the text.] Previous molecular studies suggest that maize (Zea mays L.) and other important crops such as squashes (Cucurbita spp.) were domesticated in the region. Our combined pollen, phytolith, charcoal, and sedimentary studies indicate that during the late glacial period (14,000-10,000 B.P.), lake beds were dry, the climate was cooler and drier, and open vegetational communities were more widespread than after the Pleistocene ended. Zea was a continuous part of the vegetation since at least the terminal Pleistocene. During the Holocene, lakes became important foci of human activity, and cultural interference with a species-diverse tropical forest is indicated. Maize and squash were grown at lake edges starting between 10,000 and 5,000 B.P., most likely sometime during the first half of that period. Significant episodes of climatic drying evidenced between 1,800 B.P. and 900 B.P. appear to be coeval with those documented in the Classic Maya region and elsewhere, showing widespread instability in the late Holocene climate. PMID:17537917

  4. Ages and inferred causes of late Pleistocene glaciations on Mauna Kea, Hawai'i

    Pigati, J.S.; Zreda, M.; Zweck, C.; Almasi, P.F.; Elmore, D.; Sharp, W.D.

    2008-01-01

    Glacial landforms on Mauna Kea, Hawai'i, show that the summit area of the volcano was covered intermittently by ice caps during the Late Pleistocene. Cosmogen 36Cl dating of terminal moraines and other glacial landforms indicates that the last two ice caps, called Older Makanaka and Younger Makanaka, retreated from their maximum positions approximately 23ka and 13ka, respectively. The margins and equilibrium line altitudes of these ice caps on the remote, tropical Pacific island were nearly identical, which would seem to imply the same mechanism for ice growth. But modelling of glacier mass balance, combined with palaeotemperature proxy data from the subtropical North Pacific, suggests that the causes of the two glacial expansions may have been different. Older Makanaka airatop Mauna Kea was likely wetter than today and cold, whereas Younger Makanaka times were slightly warmer but significantly wetter than the previous glaciation. The modelled increase in precipitation rates atop Mauna Kea during the Late Pleistocene is consistent with that near sea level inferred from pollen data, which suggests that the additional precipitation was due to more frequent and/ or intense tropical storms associated with eastward-moving cold fronts. These conditions were similar to modern La Ni??a (weak ENSO) conditions, but persisted for millennia rather than years. Increased precipitation rates and the resulting steeper temperature lapse rates created glacial conditions atop Mauna Kea in the absence of sufficient cooling at sea level, suggesting that if similar correlations existed elsewhere in the tropics, the precipitation-dependent lapse rates could reconcile the apparent difference between glacial-time cooling of the tropics at low and high altitudes. Copyright ?? 2008 John Wiley & Sons, Ltd.

  5. Ancient DNA analyses exclude humans as the driving force behind late Pleistocene musk ox (Ovibos moschatus) population dynamics

    Campos, Paula F; Willerslev, Eske; Sher, Andrei;

    2010-01-01

    The causes of the late Pleistocene megafaunal extinctions are poorly understood. Different lines of evidence point to climate change, the arrival of humans, or a combination of these events as the trigger. Although many species went extinct, others, such as caribou and bison, survived...... change), a hypothesis supported by historic observations on the sensitivity of the species to both climatic warming and fluctuations....

  6. Late Holocene stratigraphy of the Tetimpa archaeological sites, northeast flank of Popocatepetl volcano, central Mexico

    Panfil, M.S.; Gardner, T.W.; Hirth, K.G.

    1999-01-01

    Late Holocene (240 km2 on the east side of the volcano with >25 cm of tephra. Lavas from eruptive sequence I dammed drainage in the lowland area near the town of San Nicolas and caused local upstream deposition of as much as 30 m of lacustrine silts, clays, and sands. These lacustrine deposits record an eruptive hiatus for the Tetimpa area of about 750 14C yr: between ca. 2100 and ca. 1350 yr B.P., no major tephras were deposited in the Tetimpa area. In upland areas, this time period is represented by an unconformity and by Entisols formed in the top of pumice deposits and lavas from eruptive sequence I. Artifacts, agricultural furrows, and dwellings record human reoccupation of this surface. At the end of this hiatus, several lahars were deposited above the lacustrine sequence and locally above the Entisol in upland positions adjacent to streams. Between ca. 1350 and ca. 1200 yr B.P., tephras from eruptive sequence II buried these paleosols, occupation sites, lacustrine sediments, and lahars. Andesitic (~62% SiO2) pumice lapilli deposits in the Tetimpa area record three pumice-fall eruptions directed northeast and east of the crater. The first and smallest of these (maximum Tetimpa area thickness = 12 cm; >52 km2 covered by >25 cm) took place at ca. 1350 yr B.P. and was accompanied by pyroclastic surge events preserved in the Tetimpa area by charcoal, sand waves, and cross-stratified sand-sized tephra. At ca. 1200 yr B.P., the products of two Plinian-style events and additional pyroclastic surges reached the Tetimpa area. The largest of these tephra-fall events covered the Tetimpa area with 0.5-1 m of tephra and blanketed an area of >230 km2 with a thickness of >25 cm. The Tetimpa record confirms two of the four periods of explosive volcanism recognized by studies conducted around Popocatepetl in the past 30 yr. Eruptive sequence I corresponds to the explosive period between 2100 and 2500 yr B.P., and eruptive sequence II corresponds to the period between 900 and

  7. Relic Late Pleistocene fluvial forms as geomorphic archives indicating periods of high climatic runoff over the East European Plain

    Panin, Andrei; Belyaev, Yury; Eremenko, Ekaterina; Sidorchuk, Alexei

    2014-05-01

    therefore exhibits much abundant surface runoff than those at present. Dating of buried balkas has until recent times been based either on pollen spectra from peat deposits (in central EEP), or on stratigraphy of paleosoils found in the bottom of paleoforms (in southern EEP). Both markers point at Eemian (MIS 5e) age of their stabilization and therefore pre-Eemian (late MIS 6?) age of incision. However first attempt of OSL dating gave the contradictory result of filling of a 6-m deep balka by slopewash sediments during 80-70 ka BP. Questionable is the >30-ka delay between the soil formation in the balka bottom and start of its filling. It may mean either post-Eemian age of the soil, which would be unfortunate for the regional soil stratigraphy, or insufficient sensitivity of local quartz at ages close to Eemian. The conclusion is that geomorphic evidences make unique palaeohydrological archives that document changes not recorded in other types of palaeoenvironmental data, but they suffer from uncertainties and low resolution of dating. This presentation contributes to RFBR Projects 14-05-00119 and 14-05-00146.

  8. Late Silurian and Early Devonian conodont stratigraphy in the Prague Synform and correlation of bioevents

    Slavík, Ladislav

    Buenos Aires: Asociación Paleontológica Argentina, 2013 - (Albanesi, G.; Ortega, G.). s. 149-149 [Conodonts from the Andes : International Conodont Symposium /3./. 15.07.2013-19.07.2013, Mendoza] Institutional support: RVO:67985831 Keywords : conodonts * stratigraphy * Silurian * Devonian Subject RIV: DB - Geology ; Mineralogy

  9. Carbon cycle instability as a cause of the late Pleistocene ice age oscillations - Modeling the asymmetric response

    Saltzman, Barry; Maasch, Kirk A.

    1988-01-01

    A dynamical model of the Pleistocene ice ages is presented, which incorporates many of the qualitative ideas advanced recently regarding the possible role of ocean circulation, chemistry, temperature, and productivity in regulating long-term atmospheric carbon dioxide variations. This model involves one additional term (and free parameter) beyond that included in a previous model (Saltzman and Sutera, 1987), providing the capacity for an asymmetric response. It is shown that many of the main features exhibited by the delta(O-18)-derived ice record and the Vostok core/delta(C-13)-derived carbon dioxide record in the late Pleistocene can be deduced as a free oscillatory solution of the model.

  10. Augustine Volcano's late Pleistocene rhyolite eruption and its modern-day residuum

    Coombs, M. L.; Vazquez, J. A.

    2012-12-01

    appears as old as ca. 50 ka. Thus zircon crystallization in the rhyolite dominantly occurred just prior to eruption, with subordinate entrainment of older antecrysts. Gabbro inclusions erupted in 2006 contain zircons with core 238U-230Th ages that are indistinguishable from the dominant rhyolite age of ca. 27 ka. A few small zircons from gabbros are in 238U-230Th secular equilibrium, yield U-Pb ages of ca. 80-1800 Ma, and are true xenocrysts inherited from basement rocks. Based on the similarity in zircon ages and whole-rock geochemical affinity between late Pleistocene rhyolite and 2006 gabbroic inclusions, we suggest that the rhyolite formed via melt extraction from an andesitic crystal mush, of which the 2006 gabbro xenoliths are the residuum. A scarcity of zircons older than ca. 50 ka suggests that Augustine may not be underlain by a long-lived magmatic system, or conversely, that small but frequent andesitic eruptions of the sort that occurred prior to and after the generation of the Pleistocene rhyolite do not allow for significant zircon crystallization. Larsen, J.F., et al., 2010, USGS Prof. Paper 1769, Chap. 15, p. 335-382 Waitt, R.B., and Beget, J.E., 2009, USGS Prof. Paper 1762

  11. Correlation of the Late Pleistocene Usselo Horizon (Europe) and the Clovis Layer (North America)

    Kloosterman, J. B.

    2007-05-01

    In 1940, a dark charcoal-rich layer, 10 to 15cm thick, was found within the Late Pleistocene Coversands of the Netherlands, and named the Usselo Layer (de Laag van Usselo) by its discoverer, archaeologist CCJW Hijszeler (1902-1982). Usselo is a village near Enschedé, a few kilometres from the Dutch-German border. Research started after the war, and publications, both scientific and popular, came forth in the 1950s. By pollen content, the layer was dated to the Alleröd, the last interstadial of the Würm (Wisconsin) glaciation; radiocarbon dating indicated (pre-AMS) dates of about 11,200 14C BP. Identification of the layer at other localities was visual, and it was found in Belgium, France, Germany, Poland, and Belarus; it was also found in the UK and in Denmark, in which countries, however, no correlation was made with the other occurrences. Hijszeler had found the layer all over the Netherlands and abroad from Ostende to Hamburg, and he hypothesized the cause as a general wildfire provoked by the eruption of an Eiffel volcano. The European geologists and archaeologists, however, did not adopt his views and interpreted the layer as a paleosol, vitiating the chronology by representing the layer as the result of a long development, instead of as an eolian sediment laid down perhaps in a day or even less that provides us with a sharp marker horizon. The prehistoric Clovis culture of North America was found in the 1930s and dated to the Twocreekan, the last interstadial of the Wisconsin glaciation. The Clovis layer was especially investigated by archaeologist C.Vance Haynes Jr. Visually, the layer is easily identifiable with the Usselo Horizon of Europe. Its stratigraphic position is coincident with the end of the Clovis culture and with the disappearance of the Pleistocene megafauna. In Europe, there is a clear correlation with the sudden demise of the Magdalenian culture, best known for the Franco-Cantabrian cave paintings, and with megafaunal extinctions such as

  12. Stratigraphy of the Pleistocene, phonolitic Cão Grande Formation on Santo Antão, Cape Verde

    Eisele, S.; Freundt, A.; Kutterolf, S.; Ramalho, R. S.; Kwasnitschka, T.; Wang, K.-L.; Hemming, S. R.

    2015-08-01

    The Cão Grande Formation (CGF) on the western plateau of Santo Antão Island is part of the younger volcanic sequence that originated from both, basanitic and nephelinitic magmatic suites, respectively called COVA and COROA suites. Based on our detailed revised stratigraphy of the CGF, including two yet unknown tephra units, we can show that both suites produced multiple, highly differentiated eruptions over a contemporaneous period. Correlations of CGF tephras with marine ash layers provide distal dispersal data for Cão Grande I (CG I) and also identify two highly explosive, phonolitic eruptions that pre-date the CGF tephra deposits known on land. Within the CGF, the lowermost, 220 ± 7 ka old unit Canudo Tephra (CT; COVA suite) comprises phonolitic fall deposits and ignimbrites; it is partly eroded and overlain by debris flow deposits marking a hiatus in highly differentiated eruptions. The phonolitic CG I Tephra (COROA suite) consists of an initial major Plinian fall deposit and associated ignimbrite and terminal surge deposits. This is immediately overlain by the phonolitic to phono-tephritic Cão Grande II (CG II; COVA suite), a complex succession of numerous fallout layers and density-current deposits. CG I and CG II have radiometric ages of 106 ± 3 ka and 107 ± 15 ka, respectively, that are identical within their error limits. The youngest CGF unit, the Furninha Tephra (FT; COROA suite), consists of three foidic-phonolitic fall deposits interbedded with proximal scoria deposits from a different vent. The phonolitic eruptions switched to and fro between both magmatic suites, in each case with a stronger first followed by a weaker second eruption. Each eruption evolved from stable to unstable eruption columns. During their terminal phases, both magma systems also leaked evolved dome-forming lavas next to the tephras. Distal ashes increase the CG I tephra volume to ~ 10 km3, about twice the previously published estimate. The tephra volume of CG II is ~ 3 km

  13. Subsistence strategies in Argentina during the late Pleistocene and early Holocene

    Martínez, Gustavo; Gutiérrez, María A.; Messineo, Pablo G.; Kaufmann, Cristian A.; Rafuse, Daniel J.

    2016-07-01

    This paper highlights regional and temporal variation in the presence and exploitation of faunal resources from different regions of Argentina during the late Pleistocene and early Holocene. Specifically, the faunal analysis considered here includes the zooarchaeological remains from all sites older than 7500 14C years BP. We include quantitative information for each reported species (genus, family, or order) and we use the number of identified specimens (NISP per taxon and the NISPtotal by sites) as the quantitative measure of taxonomic abundance. The taxonomic richness (Ntaxatotal and Ntaxaexploited) and the taxonomic heterogeneity or Shannon-Wiener index are estimated in order to consider dietary generalization or specialization, and ternary diagrams are used to categorize subsistence patterns of particular sites and regions. The archaeological database is composed of 78 sites which are represented by 110 stratigraphic contexts. Our results demonstrate that although some quantitative differences between regions are observed, artiodactyls (camelids and deer) were the most frequently consumed animal resource in Argentina. Early hunter-gatherers did not follow a specialized predation strategy in megamammals. A variety in subsistence systems, operating in parallel with a strong regional emphasis is shown, according to specific environmental conditions and cultural trajectories.

  14. Paleoecological and climatic implications of stable isotope results from late Pleistocene bone collagen, Ziegeleigrube Coenen, Germany

    Wißing, Christoph; Matzerath, Simon; Turner, Elaine; Bocherens, Hervé

    2015-07-01

    Climatic and ecological conditions during Marine Oxygen Isotope Stage (MIS) 3 are complex and the impact of cold spells on the ecosystems in Central Europe still needs to be investigated thoroughly. Ziegeleigrube Coenen (ZC) is a late Pleistocene MIS 3 locality in the Lower Rhine Embayment of Germany, radiocarbon-dated to > 34 14C ka BP. The site yielded a broad spectrum of mammal species. We investigated the carbon (δ13C), nitrogen (δ15N) and sulfur (δ34S) isotope signatures of bone collagen, since these are valuable tools in characterizing ecological niches, environmental conditions and aspects of climate and mobility. By comparison with pre- and post-Last Glacial Maximum (LGM) sites in Central Europe we show that ZC belongs in a cold event of MIS 3 and was climatically more similar to post-LGM sites than to pre-LGM sites. However, the trophic structure resembled that of typical pre-LGM sites in Belgium. This cold event in MIS 3 changed the bottom of the foodweb, but do not seem to have had a direct impact on the occurrence of the mammalian species and their ecological distribution. Apparently the (mega-) faunal community could adapt also to harsher environmental conditions during MIS 3.

  15. Sedimentology and mineralogy of Libertad formation (late pleistocene) related to local fauna La Paz (Montevideo- Uruguay)

    The Local Fauna La Paz (Montevideo, Uruguay) includes skeletal remains of taxa that are characteristic of the Late Pleistocene: Glyptodon clavipes, Doedicurus sp., Panochthus sp., Lestodon sp., Macrauchenia patachonica, Stegomastodon waringi, Toxodon platensis, among others. This paper aims to contribute to the understanding of sedimentary processes acting, considering litofaciological and mineralogical aspects of sediment involved, responsible for the accumulation of bonebed. To meet the targets was lifted a detail stratigraphic section; for mineralogical studies were collected representative samples from each individual litofacies and clays were treated for the purposes of being subjected to analysis by X-ray diffractometer. The study was supplemented with a textural and compositional observation of silt and sand fraction through binocular magnifier and petrographic microscope. According to the sedimentological aspects and some taphonomic features of the bonebed such as: facies settling, the absence of sedimentary structures (massive deposit) and grainselection, along with the complete dismantling and chaotic disposal of materials, and the degree of angularity of the largest clasts, it follows that a mud flow was the last reason on the transportation and deposition of remains. The results of the X-ray diffraction reveal the predominance of chlorites and smectites on sepiolite. Previous studies suggested that the lithostratigraphic unit including the remains was the Dolores Formation. However, considering the evolutionary Quaternary model and geomorphological appearance, we consider these sediments belonging to the Libertad Formation

  16. Middle and Late Pleistocene paleoscape modeling along the southern coast of South Africa

    Fisher, Erich C.; Bar-Matthews, Miryam; Jerardino, Antonieta; Marean, Curtis W.

    2010-06-01

    Changing climates, environment, and sea levels during the Middle and Late Pleistocene must have had significant impacts on early modern humans and their behavior. However, many important archaeological sites occur along the current coastline of South Africa where the gradual slope of the offshore Agulhas Bank meant that small changes to sea level height potentially caused significant shifts in coastline position. The geographic context of these currently coastal sites would have been transformed by sea level shifts from coastal to near-coastal to fully terrestrial. To understand human adaptations as reflected in the archaeological deposits of these now-coastal sites we need to accurately model coastline position through time. Here, we introduce a Paleoscape model as a conceptual tool to ground the records for human behavioral evolution within a dynamic model of paleoenvironmental changes. Using integrated bathymetric datasets, GIS, and a relative sea level curve we estimate the position of the coastline at 1.5 ka increments over the last ˜420,000 years. We compare these model predictions to strontium isotope ratios from speleothems as an independent test and then compare the coastline predictions to evidence for shellfish exploitation through time. Both tests suggest our model is relatively robust. We then widen our paleoscape model to most of the Cape region and compare the predictions of this broadened model to evidence from Blombos cave.

  17. Characteristics of the active Luoshan Fault since Late Pleistocene, North Central China

    M. Fengying

    2003-06-01

    Full Text Available The Luoshan Fault located at the northeastern margin of Tibet plateau strikes roughly N-S, and is composed of six left-stepping sections with a total length of 60 km. Much evidence suggests that the Luoshan Fault is a reverse right-lateral strike-slip fault. The largest right-lateral strike-slip displacement and the most abundant dextral offset phenomena are located along the central section. Based on the right-lateral strike-slip offsets of the oldest alluvial fan, and of a gully and on the average displacement of the same order of gullies, the minimum slip-rate has been 2.15 ± 0.2 mm/yr since Late Pleistocene. Many surface rupture phenomena, such as fault scarps with fresh free-face, ground fissures, displacements of very young gullies, imply that a recent earthquake occurred along this fault. Combining the historical catalogue and our results, we believe that the 1561 A.D. earthquake was produced by the Luoshan Fault. Three paleoearthquakes were determined by means of paleoseismic studies along the Luoshan Fault: they occurred after 8200 ± 600 years BP, between 3130 ± 240 years BP and 4150 ± ± 120 years C.BP, and before 2230 ± 170 years BP, respectively.

  18. Optically stimulated luminescence age controls on late Pleistocene and Holocene coastal lithosomes, North Carolina, USA

    Mallinson, D.; Burdette, K.; Mahan, S.; Brook, G.

    2008-01-01

    Luminescence ages from a variety of coastal features on the North Carolina Coastal Plain provide age control for shoreline formation and relative sea-level position during the late Pleistocene. A series of paleoshoreline ridges, dating to Marine Isotope Stage (MIS) 5a and MIS 3 have been defined. The Kitty Hawk beach ridges, on the modern Outer Banks, yield ages of 3 to 2??ka. Oxygen-isotope data are used to place these deposits in the context of global climate and sea-level change. The occurrence of MIS 5a and MIS 3 shorelines suggests that glacio-isostatic adjustment (GIA) of the study area is large (ca. 22 to 26??m), as suggested and modeled by other workers, and/or MIS 3 sea level was briefly higher than suggested by some coral reef studies. Correcting the shoreline elevations for GIA brings their elevation in line with other sea-level indicators. The age of the Kitty Hawk beach ridges places the Holocene shoreline well west of its present location at ca. 3 to 2??ka. The age of shoreline progradation is consistent with the ages of other beach ridge complexes in the southeast USA, suggesting some regionally contemporaneous forcing mechanism. ?? 2007 University of Washington.

  19. Late Pleistocene Interstadial Environment on Faddeyevskiy Island, East-Siberian Sea, Russia

    Andreev, Andrei A.; Peteet, Dorothy M.; Romanenko, Fedor A.; Filimonova, Ludmila V.; Sulerzhitsky, Leopold D.; Tarasov, Pavel E.

    1999-01-01

    Pollen, plant macrofossil, LOI and radiocarbon analyses of a 1.4-m section from Faddeyevskiy Island, Novosibirskie Ostrova archipelago (75 deg 20 min N, 143 deg 50 min E, 30m elevation) provide new information on the Late Pleistocene interstadial environmental history of this high Arctic region. Bulk radiocarbon dates of 25,700 +/- 1000, 32,780 +/- 500, 35,200 +/- 650 and two AMS dates of 29,950 +/- 660 and 42,990 +/- 1280 indicate that the deposits accumulated during the Kargian (Boutellier) interval. Numerous mammoth (Mammuthus primigenius) remains collected in the vicinity of the site were radiocarbon dated to 36,700-18,500 yr. BP. Rare bison (Bison priscus) bones were dated to 32,200 +/- 600 and 33,100 +/- 320. Poaceae, Cyperaceae, and Artemisia pollen dominate the pollen spectra with some Ranunculaceae, Caryophyllaceae, Rosaceae, and Compositae. These pollen spectra reflect a tundra-steppe vegetation which probably was dominant on the exposed shelf of the Arctic Ocean. The presence of Carex macrofossils infer a summer climate two degrees warmer than today. The productivity of this local vegetation during the Kargian interstadial was apparently high enough to feed the grass-eater herds.

  20. Meltwater palaeohydrology of the Baker River basin (Chile/Argentina) during Late Pleistocene deglaciation of the Northern Patagonia Icefield

    Thorndycraft, Varyl; Bendle, Jacob; Benito, Gerardo; Sancho, Carlos; Palmer, Adrian; Rodríguez, Xavier

    2016-04-01

    The Late Pleistocene deglaciation of the Northern Patagonia Icefield (NPI) was characterised by rapid ice sheet thinning and retreat, and the development of large proglacial lake systems characterised by continental scale drainage reversals. In this region, research has focused primarily on the identification of former ice-limits (e.g. moraine ridges) for geochronological analyses, with little attention given to the meltwater palaeohydrology of major river valleys. The Baker River catchment drains the majority of the eastern ice shed of the NPI, with a basin area of 29,000 km2 that includes the large transboundary lakes of General Carrera/Buenos Aires and Cochrane/Puerreydón. The Baker River valley is aligned north to south, crossing the east-west valleys of the main NPI outflow glaciers, and thus represents an important aspect of regional Late Pleistocene palaeogeography. The Baker River valley therefore has the potential to refine regional models of deglaciation through better understanding of relationships between glacier dynamics, ice dammed lakes and meltwater pathways. Here we present geomorphological mapping from the Atlantic-Pacific drainage divide (over 150 km east of the Cordillera) to the lower Baker valley, in order to reconstruct Late Pleistocene palaeohydrology. We provide new mapping of palaeolake shoreline elevations and evidence for glacial lake outburst flood (GLOF) pathways that require a re-evaluation of the currently accepted palaeogeographic models. For example, the palaeohydrological evidence does not support existing models of a unified Buenos Aires/Puerreydón mega-lake at ca. 400m elevation. We propose a relative chronology of palaeohydrological events that help refine the published moraine chronology derived from cosmogenic nuclide exposure dating. Controls on Late Pleistocene meltwater palaeohydrology of the Baker catchment are discussed, including the interplay of glacial processes and regional tectonics, in particular, dynamic

  1. Greigite detected as dominating remanence carrier in Late Pleistocene sediments, Lisan formation, from Lake Kinneret (Sea of Galilee), Israel

    H. Ron; Norbert Nowaczyk; Ute Frank; Schwab, Markus J.; Rudolf Naumann; B. Striewski; Agnon, A.

    2007-01-01

    A rock magnetic investigation of three sedimentary cores of Lisan formation of late Pleistocene age from Lake Kinneret (Sea of Galilee) northern Israel demonstrates that the magnetization of these sediments is controlled by various degrees of a secondary chemical remanent magnetization (CRM) carried by greigite (Fe3S4). This CRM is superimposed on a primary detrital remanent magnetization (DRM) that resides in Ti-magnetite. This finding is independently confirmed by X-ray diffraction (XRD) me...

  2. Late Pleistocene valley fills source sediment flux of Tibetan Plateau margin rivers, Zanskar, India

    Blöthe, J. H.; Munack, H.; Korup, O.; Fulop, R. H.; Codilean, A.; Fink, D.

    2015-12-01

    The Indus and its tributaries, one of Asia's largest river systems, drain the NW Himalaya and the Transhimalayan ranges that border the western Tibetan Plateau margin. From the internally drained low-relief areas of the Tibetan Plateau, local relief increases towards the Western Himalayan Syntaxis, where it exceeds 7 km. Simultaneously, average denudation rates rise from as little as 10 mm ka-1 at the Tibetan Plateau margin to rates of >1000 mm ka-1 close to the western Himalayan Syntaxis. In this rugged bedrock landscape, river valleys frequently alternate between deeply incised gorges and broad alluviated reaches. Vast fill terrace staircases of up to 400 m height above current river levels, and intercalated lake sediments point to repeated phases of incision and aggradation within the region. Despite a broad interest in a better understanding of mechanisms that modulate plateau erosion, age constraints on the generation of these impressive features remain sparse, though indicate mainly Pleistocene formation ages. Here we present new data from the More Plains section, a vast sedimentary fill, located in the headwaters of the Zanskar River, the largest tributary to the upper Indus. The vast sedimentary successions of the More Plains originally belonged to a former endorheic basin that has been tapped by the Zanskar River, today revealing a sedimentary exposures of >250 m thickness. We combine morphometric analysis and field based observations with 10Be surface exposure dating and basin-wide denudation rates to constrain the late Quaternary history of this setting. Analysis of a 10Be depth profile on top of the More Plains section indicate a surface exposure age of ~125 +/- 15 ka, which is supported by ages from nearby amalgamated surface samples. Grounding on a morphometric approach, we estimate that ~1.65-1.95 km3 were removed from this section by fluvial erosion since aggradation ceased, requiring a specific sediment yield of 85-100 t km-2 yr-1 averaged over the

  3. Tanque Loma, a new late-Pleistocene megafaunal tar seep locality from southwest Ecuador

    Lindsey, Emily L.; Lopez R., Eric X.

    2015-01-01

    Fossil deposits in the petroleum-rich sediments of the Santa Elena Peninsula in southwestern Ecuador contain some of the largest and best-preserved assemblages of Pleistocene megafaunal remains known from the neotropics, and thus represent an opportunity to greatly expand our knowledge of Pleistocene paleoecology and the extinction of Quaternary megafauna in this region. This paper reports data from excavations at Tanque Loma, a late-Pleistocene locality on the Santa Elena Peninsula that preserves a dense assemblage of megafaunal remains in hydrocarbon-saturated sediments along with microfaunal and paleobotanical material. The megafauna bones are concentrated in and just above a ˜0.5 m thick asphaltic layer, but occur sparsely and with poorer preservation up to 1 m above this deposit. Several meters of presumed-Holocene sediments overlying the megafauna-bearing strata are rich in bones of microvertebrates including birds, squamates, and rodents. These are interpreted as raptor assemblages. While over 1000 megafaunal bones have been identified from the Pleistocene strata at Tanque Loma, more than 85% of these remains pertain to a single species, the giant ground sloth Eremotherium laurillardi. Only five other megafauna taxa have been identified from this site, including Glossotherium cf. tropicorum, Holmesina occidentalis, cf. Notiomastodon platensis, Equus (Amerhippus) c.f. santaeelenae, and a cervid tentatively assigned to cf. Odocoileus salinae based on body size and geography. No carnivores have yet been identified from Tanque Loma, and microvertebrate remains are extremely rare in the Pleistocene deposits, although terrestrial snail shells and fragmented remains of marine invertebrates are occasionally encountered. Accelerator Mass Spectrometry radiocarbon dates on Eremotherium and cf. Notiomaston bones from within and just above the asphaltic layer yielded dates of ˜17,000 - 23,500 radiocarbon years BP. Taken together, the taxonomic composition, taphonomy

  4. An enlarged parietal foramen in the late archaic Xujiayao 11 neurocranium from Northern China, and rare anomalies among Pleistocene Homo.

    Xiu-Jie Wu

    Full Text Available We report here a neurocranial abnormality previously undescribed in Pleistocene human fossils, an enlarged parietal foramen (EPF in the early Late Pleistocene Xujiayao 11 parietal bones from the Xujiayao (Houjiayao site, northern China. Xujiayao 11 is a pair of partial posteromedial parietal bones from an adult. It exhibits thick cranial vault bones, arachnoid granulations, a deviated posterior sagittal suture, and a unilateral (right parietal lacuna with a posteriorly-directed and enlarged endocranial vascular sulcus. Differential diagnosis indicates that the perforation is a congenital defect, an enlarged parietal foramen, commonly associated with cerebral venous and cranial vault anomalies. It was not lethal given the individual's age-at-death, but it may have been associated with secondary neurological deficiencies. The fossil constitutes the oldest evidence in human evolution of this very rare condition (a single enlarged parietal foramen. In combination with developmental and degenerative abnormalities in other Pleistocene human remains, it suggests demographic and survival patterns among Pleistocene Homo that led to an elevated frequency of conditions unknown or rare among recent humans.

  5. Quantifying late Pleistocene lithospheric flexure and fault movements in the Mississippi Delta

    Shen, Z.; Tornqvist, T. E.; Dawers, N. H.; Gasparini, N. M.; Milne, G. A.; Mauz, B.

    2011-12-01

    It is well known that a significant portion of the Mississippi Delta (MD) land surface is subsiding at rates on the order of a centimeter per year. Several recent studies have argued that lithospheric flexure due to sediment loading in the MD and fault movements in southeast Louisiana induce as much as ~6 mm/yr of subsidence, and therefore would be major driving forces of land-surface subsidence in the MD. However, geological rates of lithospheric flexure and fault movements have rarely been quantified. In this study, we quantify geological rates of these two processes in and near the MD by means of quartz optically-stimulated luminescence (OSL) dating of late Pleistocene sediments. Lithospheric flexure is quantified by studying long profiles of the Lower Mississippi River (LMR). Recent OSL dating of the Prairie Complex strata in the Lower Mississippi Valley (LMV) and MD identified segments of ~80 ka (MIS 5a) old LMR remnants. Comparing the reconstructed MIS 5a LMR long profile with the present-day long profile demonstrates that the former has been deformed due to lithospheric flexure associated with MD sediment loading, featuring uplift in the southern LMV and down-warping in the MD. Using the present-day long profile as a proxy for deformation of the MIS 5a long profile, the bulge in the southern LMV exhibits an average uplift rate of <0.15 mm/yr, whereas most of the MD north of 29.6°N has subsided <0.4 mm/yr on average during the past 80 ka. Farther south, where the Prairie Complex occurs 100 to 150 m below present-day sea level, subsidence rates due to lithospheric flexure may be up to 1 to 2 mm/yr. The half-wavelength of the flexural bulge in the LMV suggests a minimum elastic thickness of the lithosphere for this region of ~60 km. Fault movements were quantified at four locations along the Baton Rouge fault zone (BRFZ) in southeast Louisiana. Geomorphic and stratigraphic studies were used to identify fault-displaced strata that were subsequently OSL dated

  6. Sedimentary architecture and chronostratigraphy of a late Quaternary incised-valley fill: A case study of the late Middle and Late Pleistocene Rhine system in the Netherlands

    Peeters, J.; Busschers, F. S.; Stouthamer, E.; Bosch, J. H. A.; Van den Berg, M. W.; Wallinga, J.; Versendaal, A. J.; Bunnik, F. P. M.; Middelkoop, H.

    2016-01-01

    This paper describes the sedimentary architecture, chronostratigraphy and palaeogeography of the late Middle and Late Pleistocene (Marine Isotope Stage/MIS 6-2) incised Rhine-valley fill in the central Netherlands based on six geological transects, luminescence dating, biostratigraphical data and a 3D geological model. The incised-valley fill consists of a ca. 50 m thick and 10-20 km wide sand-dominated succession and includes a well-developed sequence dating from the Last Interglacial: known as the Eemian in northwest Europe. The lower part of the valley fill contains coarse-grained fluvio-glacial and fluvial Rhine sediments that were deposited under Late Saalian (MIS 6) cold-climatic periglacial conditions and during the transition into the warm Eemian interglacial (MIS 5e-d). This unit is overlain by fine-grained fresh-water flood-basin deposits, which are transgressed by a fine-grained estuarine unit that formed during marine high-stand. This ca. 10 m thick sequence reflects gradual drowning of the Eemian interglacial fluvial Rhine system and transformation into an estuary due to relative sea-level rise. The chronological data suggests a delay in timing of regional Eemian interglacial transgression and sea-level high-stand of several thousand years, when compared to eustatic sea-level. As a result of this glacio-isostatic controlled delay, formation of the interglacial lower deltaic system took only place for a relative short period of time: progradation was therefore limited. During the cooler Weichselian Early Glacial period (MIS 5d-a) deposition of deltaic sediments continued and extensive westward progradation of the Rhine system occurred. Major parts of the Eemian and Weichselian Early Glacial deposits were eroded and buried as a result of sea-level lowering and climate cooling during the early Middle Weichselian (MIS 4-3). Near complete sedimentary preservation occurred along the margins of the incised valley allowing the detailed reconstruction presented

  7. Variation in the nasal cavity of baboon hybrids with implications for late Pleistocene hominins.

    Eichel, Kaleigh Anne; Ackermann, Rebecca Rogers

    2016-05-01

    examining the fossil record of late Pleistocene contact. PMID:27178465

  8. Evidence of fire use of late Pleistocene humans from the Huanglong Cave, Hubei Province, China

    LIU Wu; WU XianZhu; LI YiYin; DENG ChengLong; WU XiuJie; PEI ShuWen

    2009-01-01

    Since 2004, three excavations have been carried out at a late Pleistocene human fossil site of Huan-glong Cave in Yunxi County, Hubei Province of China, which unearthed seven human teeth, dozens of stone tools, mammal fossils and other evidence indicating human activities. During the third excava-tion in 2006, in the same layer as the human teeth, we found some patches of black materials embed-ded in the deposit. We doubted that this black deposit layer is the remains of burning or even human use of fire at the cave. To further explore the possibility of human fire use at the Huanglong Cave, we examined samples directly taken from the black deposit layer and compared them with samples taken from several places in the cave using three methods: micromorphology, element content determination and deposit temperature analysis. Our results indicate that the contents of carbon element in the black deposit reach 64.59%-73.29%. In contrast, contents of carbon element of the comparative samples from other parts in the cave are only 5.82%-9.49%. The micromorphology analysis of the black de-posit samples reveals a plant structure like axial parenchyma, fibrocyte, uniseriate ray and vessel.High-temperature magnetic susceptibility measurements suggest that the stratum possibly underwent a high temperature in the nature. Based on these lab analyses, we are sure that the black layer in the Huanglong Cave is the remains of fire and combustion did occur in the cave 100000 years ago. Taking other evidence of human activities found in the Huanglong Cave into consideration, we believe that the evidence of fire from the Huanglong Cave was caused by the human activities of controlled use of fire.

  9. Stable isotope paleoecology of Late Pleistocene Middle Stone Age humans from the Lake Victoria basin, Kenya.

    Garrett, Nicole D; Fox, David L; McNulty, Kieran P; Faith, J Tyler; Peppe, Daniel J; Van Plantinga, Alex; Tryon, Christian A

    2015-05-01

    Paleoanthropologists have long argued that environmental pressures played a key role in human evolution. However, our understanding of how these pressures mediated the behavioral and biological diversity of early modern humans and their migration patterns within and out of Africa is limited by a lack of archaeological evidence associated with detailed paleoenvironmental data. Here, we present the first stable isotopic data from paleosols and fauna associated with Middle Stone Age (MSA) sites in East Africa. Late Pleistocene (∼100-45 ka, thousands of years ago) sediments on Rusinga and Mfangano Islands in eastern Lake Victoria (Kenya) preserve a taxonomically diverse, non-analog faunal community associated with MSA artifacts. We analyzed the stable carbon and oxygen isotope composition of paleosol carbonate and organic matter and fossil mammalian tooth enamel, including the first analyses for several extinct bovids such as Rusingoryx atopocranion, Damaliscus hypsodon, and an unnamed impala species. Both paleosol carbonate and organic matter data suggest that local habitats associated with human activities were primarily riverine woodland ecosystems. However, mammalian tooth enamel data indicate that most large-bodied mammals consumed a predominantly C4 diet, suggesting an extensive C4 grassland surrounding these riverine woodlands in the region at the time. These data are consistent with other lines of paleoenvironmental evidence that imply a substantially reduced Lake Victoria at this time, and demonstrate that C4 grasslands were significantly expanded into equatorial Africa compared with their present distribution, which could have facilitated dispersal of human populations and other biotic communities. Our results indicate that early populations of Homo sapiens from the Lake Victoria region exploited locally wooded and well-watered habitats within a larger grassland ecosystem. PMID:25805041

  10. Late-Pleistocene avifaunas from Cape Wanbrow, Otago, South Island, New Zealand

    Fossil avifaunas from the Hillgrove Formation at Boatmans Harbour, Ruby Gully, and Old Rifle Butts, all on Cape Wanbrow, Oamaru, north-east Otago, are listed. The marine beach sands and gravels at Old Rifle Butts that form the lowest part of the Hillgrove Formation and overlie the palaeo-wave platform were deposited during the last interglacial ∼ 130-110 kyr BP (Oxygen Isotope Stage 5). There are a few small avifaunas (totalling 11 spp.) from these beach sediments (J41/f8710, f8214, f8227). The colluvial, valley-fill deposits in Ruby Gully and at its mouth are the youngest in the sequence. Radiocarbon dating indicates their emplacement between 27 and 34 kyr BP, or the later part of Oxygen Isotope Stage 3. If these ages are representative of the true age of the samples and not the limitations of radiocarbon technology, they indicate that these deposits in Ruby Gully are much younger than the beach deposits. Radiocarbon ages on a pitfall fauna from a small cave 3-4 m above the base of the Hillgrove Formation indicate that the cave fauna has a similar age as that in Ruby Gully. The dune and interdune waterlaid deposits at Old Rifle Butts (>2 m above the wave platform) may date from an unknown time between 100 and 35 kyr BP or be coeval with those in Ruby Gully. Fifty-three species of bird (32 land and freshwater taxa) are represented in the combined avifaunas making this the richest Pleistocene avifauna known from New Zealand. All bird taxa are known from Late Holocene avifaunas in the eastern South Island. Key taxa (Pachyornis elephantopus, Emeus crassus, Euryapteryx geranoides, Coturnix, Chenonetta, Cnemiornis, Harpagornis, Fulica, Porphyrio, Gallinula) indicate that the habitat was mainly grassland and shrubland. Tuatara, indeterminate skinks, and seals are also present. (author). 57 refs., 10 figs., 2 tabs

  11. The late Pleistocene ground surface temperature and corrected heat flow density for northern part of Poland

    Szewczyk, J.; Gientka, D.

    2003-04-01

    Paleoclimatic ground surface temperature (GST) changes in last 100 ka years are a major factor causing vertical variation of terrestrial heat flow density (HFD). The value of this parameter important for thermal and rheological modelling may be considerably influenced by paleoclimatic factor and should be corrected for this reason. Very important criteria for studying paleoclimatic events on boreholes is the knowledge of depth distribution of thermal conductivity. However, core samples from majority of deep boreholes are hardly available and laboratory measurements of thermal conductivity are very scarce and sometimes not confident. We used a method of estimating the thermal conductivity from well logging data interpretation. The thermal conductivity was calculated using volumetric model of rock with mean geometric formula. The synthetic temperature logs (T_s) based on this data are an "active" method of investigation of vertical variation of HFD and GST determination. For a majority of deep boreholes in Polish Lowlands in uppermost part (GST in the Late Pleistocene for the representative data for 59 deep boreholes for the N of Poland. The GST was -5.17 +/- 5.45^oC. The observed big scatter of presented results seems to be consequence of unstable thermal conditions and bad calibration of old temperature logs. The amplitude of post glacial warming (ΔGST) is not less then +13.1^oC. The history of climate for the last 500 ka years shows that this time was spent mainly in ice age and this is "normal" state of HFD. The presented method of investigations seems to be very effective for determination of HFD for this condition.

  12. Vegetation Dynamics in the Kenai Lowlands, Alaska during the Late Pleistocene and Holocene

    Jones, M. C.; Peteet, D. M.

    2005-12-01

    The use of paleoinformation through ecosystem reconstruction can help us understand the behavior and sensitivity of the boreal forest as climate continues to change. A 2.5-meter sediment core extracted from Swanson Fen, a muskeg in the northern Kenai Lowlands on the Kenai Peninsula, Alaska, provides a sensitive Holocene paleoenvironmental record that lies in an ecotone between interior boreal forest and maritime coastal forest today. The core was sampled at 2-cm intervals and processed for pollen and spores. Five intervals were dated using AMS radiocarbon dating, and the basal macrofossils produced an age of 12,245 ±45 radiocarbon years. The central Kenai Peninsula Lowlands underwent a number of marked vegetational and climatic changes since deglaciation. Four distinct vegetation zones reveal changes starting in the late Pleistocene. The pioneer vegetation includes a dominance of herbaceous ( Artemisia, Apiaceae, Asteroideae)and shrubby ( Betula) species. The second zone (beginning at 9890±45 radiocarbon years) and marking the Holocene boundary, shows a striking increase in Polypodiaceae (ferns) and Picea (spruce) and a decrease in shrubby species such as Betula, indicative of warming. The third zone indicates a decline in Polypodiaceae and a reemergence of Betula species, while the final most recent zone reveals a rapid resurgence in Picea and Tsuga mertensiana (Mountain hemlock) species. While a general warming trend occurred following deglaciation, vegetation patterns suggest extended periods of increased precipitation, for example in the early Holocene, as is evidenced by the plethora of Polypodiaceae. A movement and an intensification of the Aleutian Low could explain these periods of increased precipitation over the Kenai Peninsula. Alternatively, this spike in Polypodiaceae can be explained by increased disturbance. The presence of 10 % Picea pollen at the base of the core suggests that one of the Picea species may have survived the last glaciation in the

  13. Early Late Cretaceous to Holocene seismic stratigraphy and geologic history of southeastern Gulf of Mexico

    Angstadt, D.M.; Austin, J.A.; Buffler, R.T.

    1985-06-01

    Multifold seismic reflection profiles were used in conjunction with results from Deep Sea Drilling Project (DSDP) Leg 77 to interpret the early Late Cretaceous to Holocene geologic history of the southeastern Gulf of Mexico. During the mid-Cenomanian(.) to early Paleocene(.), this region began to record the effects of a collision between a northward-migrating island arc (now part of Cuba) and a salient of the North American plate. More than 2 km (6,560 ft) of gravity-flow deposits accumulated in an elongate structural corridor or foredeep along the base of the modern Cuban slope, while the slope itself was the site of both folding and overthrusting. Clastics continued to dominate the depositional regime until the late Eocene, at which time the Cuban arc had been firmly welded to North America. A late middle to early late Eocene hiatus in Site 540, which coincides with a prominent regional seismic unconformity, marks the transition from predominantly terrigenous input to pelagic/hemipelagic deposition. Since the late Eocene, the southeastern gulf has recorded multiple cycles of deposition and erosion. Unconformities displayed on seismic profiles are numerous. Erosional agents have included the Gulf Stream system, and turbidity currents and debris flows concentrated in the vicinity of submarine canyons. Continuing slope instability is indicated by slide/slump planes along canyon walls.

  14. A review and synthesis of late Pleistocene extinction modeling: progress delayed by mismatches between ecological realism, interpretation, and methodological transparency.

    Yule, Jeffrey V; Fournier, Robert J; Jensen, Christopher X J; Yang, Jinyan

    2014-06-01

    Late Pleistocene extinctions occurred globally over a period of about 50,000 years, primarily affecting mammals of > or = 44 kg body mass (i.e., megafauna) first in Australia, continuing in Eurasia and, finally, in the Americas. Polarized debate about the cause(s) of the extinctions centers on the role of climate change and anthropogenic factors (especially hunting). Since the late 1960s, investigators have developed mathematical models to simulate the ecological interactions that might have contributed to the extinctions. Here, we provide an overview of the various methodologies used and conclusions reached in the modeling literature, addressing both the strengths and weaknesses of modeling as an explanatory tool. Although late Pleistocene extinction models now provide a solid foundation for viable future work, we conclude, first, that single models offer less compelling support for their respective explanatory hypotheses than many realize; second, that disparities in methodology (both in terms of model parameterization and design) prevent meaningful comparison between models and, more generally, progress from model to model in increasing our understanding of these extinctions; and third, that recent models have been presented and possibly developed without sufficient regard for the transparency of design that facilitates scientific progress. PMID:24984323

  15. Differential resilience of ancient sister lakes Ohrid and Prespa to environmental disturbances during the Late Pleistocene

    Jovanovska, Elena; Cvetkoska, Aleksandra; Hauffe, Torsten; Levkov, Zlatko; Wagner, Bernd; Sulpizio, Roberto; Francke, Alexander; Albrecht, Christian; Wilke, Thomas

    2016-02-01

    Ancient lakes, such as lakes Ohrid and Prespa on the Balkan Peninsula, have become model systems for studying the link between geological and biotic evolution. Recently, the scientific deep-drilling project Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) was initiated to better understand the environmental, climatic, and limnological evolution of the lake. It revealed that Lake Ohrid experienced a number of environmental disturbances during its ca. 2.0 million year long history. These are comprised of disturbances that lasted over longer periods of time ("press events") such as glacial-interglacial cycles and Heinrich events, as well as sudden and short disturbances ("pulse events") like the deposition of landslides, earthquakes, and volcanic ash depositions. The latter includes one of the most severe volcanic episodes during the Late Pleistocene: the eruption of the Campanian Ignimbrite (known as Y-5 marine tephra layer) from the Campi Flegrei caldera, dated to 39.6 ± 0.1 thousand years ago. The event is recorded by the deposition of a ca. 15 cm thick tephra layer in sediment cores of lakes Ohrid (DEEP-5045-1) and Prespa (Co1204). Coincidently, this pulse event is superimposed by the Heinrich H4 event, 40.4-38.4 thousand years ago. In the current paper, diatoms were used as proxies to compare the responses of these lakes to the Y-5 (pulse) and the H4 (press) disturbances. Based on stratigraphically constrained incremental sum of squares cluster (CONISS) and unconstrained Partitioning Around Medoids (PAM) analyses, we found little evidence that diatom community compositions in either lake responded to the H4 event. However, the Y-5 influx caused clear and rapid diatom community changes. After the initial response, community compositions in Lake Ohrid and, to a lesser extent, in Lake Prespa slowly returned to their quasi pre-disturbance state. Moreover, there is no evidence for disturbance-related extinction events. The combined

  16. Late Pleistocene desiccation of Lake Tana, source of the Blue Nile

    Lamb, Henry F.; Bates, C. Richard; Coombes, Paul V.; Marshall, Michael H.; Umer, Mohammed; Davies, Sarah J.; Dejen, Eshete

    2007-02-01

    High-resolution seismic data from Lake Tana, the source of the Blue Nile in northern Ethiopia, reveal a deep sedimentary sequence divided by four strong reflectors. Data from nearshore cores show that the uppermost strong reflector represents a stiff silt unit, interpreted as a desiccation surface. Channel cuts in this surface, bordered by levee-like structures, are apparent in the seismic data from near the lake margin, suggesting fluvial downcutting and over-bank deposition during seasonal flood events. Periphytic diatoms and peat at the base of a core from the deepest part of the lake overlie compacted sediments, indicating that desiccation was followed by development of shallow-water environments and papyrus swamp in the central basin between 16,700 and 15,100 cal BP. As the lake level rose, open-water evaporation from the closed lake caused it to become slightly saline, as indicated by halophytic diatoms. An abrupt return to freshwater conditions occurred at 14,750 cal BP, when the lake overflowed into the Blue Nile. Further reflection surfaces with downcut structures are identifiable in seismic images of the overlying sediments, suggesting at least two lesser lake-level falls, tentatively dated to about 12,000 and 8000 cal BP. Since Lake Victoria, the source of the White Nile, was also dry until 15,000 cal BP, and did not reach overflow until 14,500 cal BP, the entire Nile system must have been reduced to intermittent seasonal flow until about 14,500 cal BP, when baseflow was re-established with almost simultaneous overflow of the headwater lakes of both the White and Blue Nile rivers. Desiccation of the Nile sources coincides with Heinrich event 1, when cessation of northward heat transport from the tropical Atlantic disrupted the Atlantic monsoon, causing drought in north tropical Africa. The strong reflectors at deeper levels in the seismic sequence of Lake Tana may represent earlier desiccation events, possibly contemporaneous with previous Late

  17. Drainage system inversion in the Guadalentin Depression during the Late Pleistocene-Holocene (Murcia, Spain)

    This article presents the results of studies conducted in the central sector of Guadalentin depression (Murcia) for the abnormal accumulation (more than 17 m) of Pleistocene and Holocene deposits upstream of Romeral tectonic threshold (Librilla). 14C dating. ruins and archaeological sites, together with its stratigraphic analysis show that the three sequences that constitute the Holocene detrital filling of the Depression, prograded are superimposed on the upper Pleistocene travertine upstream from the confluence of the River Guadalentin the Rambla de Librilla. Between Librilla and threshold Romeral Holocene deposits only appear along the left bank (15-17m). By contrast the right side shows significant lifting of the Pleistocene travertine up area Romeral threshold, where the substrate allora Neogene. (Author) 11 refs.

  18. BODY SIZE REDUCTION AND TOOTH AGENESIS IN LATE PLEISTOCENE MELES MELES (CARNIVORA, MAMMALIA FROM INGARANO (SOUTHERN ITALY

    DAWID ADAM IURINO

    2014-03-01

    Full Text Available In mammals combined factors such as body size reduction and loss of peripheral teeth are often associated with endemism phenomena. This condition is particularly evident in insular contexts where is a complete geographic isolation. During the Pleistocene there have been several glacial stages, which changed the physiognomy of the Italian peninsula strongly influencing the distribution and morphology of mammalian faunas. Several genetic studies have shown that some Southern Italian areas have particular endemic species of small and medium size mammals. During Pleistocene these areas have been characterized by particular climatic/environmental conditions, and are generally called "glacial refugia". They represent geographically isolated areas over time, where the origin of faunas with peculiar features is favoured. In this study, the occurrence of Meles meles from the Late Pleistocene site of Ingarano (Apulia, Southern Italy is documented for the first time. This taxon is represented only by a partial skull (splancnocranum that, despite the relative completeness, includes peculiar and well-preserved dental features that could be related to a partial endemic condition. The fossil shows a reduced body size and the agenesis of peripheral teeth, both conditions that are typical of the extant badgers from Crete, Rhodes and Japan. To test this hypothesis, tomographic analysis have been provided to establish the dental agenesis, and, in order to understand the magnitude of the body size reduction, biometric analyses have been carried on. The obtained data have been compared to measures of the extant Eurasian badgers.SHORT NOTE

  19. Late Triassic - Early Jurassic successions of the Atuel depocenter: sequence stratigraphy and tectonic controls

    Silvia Lanés

    2008-12-01

    Full Text Available Biostratigraphic correlations of the Late Triassic - Early Jurassic successions of the Atuel depocenter allowed determining the accommodation changes and the possible tectonic controls on sedimentation. The Rhaetian - late Early Sinemurian deposits contain facies of slope-type fan deltas, braided fluvial systems and low sinuosity rivers with alternate bars deposited during a synrift phase. The late Early Sinemurian - Toarcian series host facies of intermediate (Gilbert to shelf type fan deltas, braided and low sinuosity fluvial systems, wave-dominated estuaries, transgressive storm-dominated and turbidite-influenced marine shelves which record the sag phase. According to different criteria two stratigraphic schemes are proposed, the first one considering tectosedimentary units (TSU and the second one using "Exxon-like" sequences. In the first scheme the synrift TSU matches the actual Precuyo Mesosequence and the sag TSU is partly equivalent to the Cuyo Mesosequence, mainly keeping the current mesosequence scheme for the Neuquén basin but assigning the fandeltaic deposits to the Precuyo Mesosequence. The second sequence scheme considers the whole Late Triassic - Early Jurassic succession as a part of the Cuyo Mesosequence, where the synrift deposits composes the detached lowstand system tract (LST and most of the sag deposits makes the transgressive system tract (TST. The basal sequence boundary does not crop out, the flooding surface at the TST base and the maximum flooding surface at the TST top are respectively marked by the lowest estuarine levels and by black shales with suboxic-compatible bivalves (Bositra sp..

  20. Late Quaternary seismo-stratigraphy of Lake Wanapitei, Sudbury, Ontario, Canada: Arguments for a possible meteorite impact origin

    Lazorek, Michael; Eyles, Nick; Eyles, Carolyn; Doughty, Mike; L'Heureux, Elizabeth; Milkereit, Berndt

    2006-12-01

    Lake Wanapitei (132.75 km2) fills what has been identified as an Eocene (c. 37 Ma) meteorite impact basin in the Canadian Shield near Sudbury, Ontario, Canada. The area was glaciated many times during the Pleistocene and the basin lies immediately north of the prominent Cartier Moraine built during the last glaciation by the retreating Laurentide Ice Sheet some 11,000 years ago. Study of the deeper geophysics of the basin using magnetic and gravity techniques, and confirmation of its origin, is hampered by lack of data regarding water depths, the form of the bedrock surface and the thickness and character of glacial and postglacial sediment. To this end, more than 300 km of high-resolution single channel seismic chirp and 200 kHz bathymetric data were collected from the basin in the summer of 2002. Water depths reach a maximum of 118 m and acoustic basement is defined by a glacially scoured bedrock surface. The overlying Pleistocene sediment fill exceeds 35 m in thickness and consists of a lowermost late-glacial succession of rhythmically laminated silty clays deposited when the basin was flooded by a deep and regionally extensive ice dammed water body (Glacial Lake Algonquin). Truncation of the upper surface of this succession across large parts of the lake floor records the drainage of Lake Algonquin and the isolation of Wanapitei Lake as a separate water body. Overlying Holocene sediment is up to 10 m thick but is markedly discontinuous and commonly occurs as mounded ‘drifts’ reflecting strong bottom currents and low inputs of modern sediment. The presence of apparently undisturbed Precambrian bedrock below large portions of the lake basin places significant constraints on the dimensions of any meteorite impact structure.

  1. Late Paleocene-early Eocene carbon isotope stratigraphy from a near-terrestrial tropical section and antiquity of Indian mammals

    Samanta, A.; Sarkar, A.; Bera, M. K.; Rai, Jyotsana; Rathore, S. S.

    2013-02-01

    Late Paleocene to early Eocene (~56 to 51 Ma) interval is characterized by five distinct transient warming (hyperthermal) events (Paleocene-Eocene thermal maximum (PETM), H1/ETM2/ELMO, H2, I1 and I2) in a super greenhouse globe associated with negative carbon isotope excursions (CIEs). Although well-documented marine records exist at different latitudes, terrestrial PETM sections are rare. In particular, almost no terrestrial records of either the PETM or early Eocene hyperthermals (EEHs) are yet available from the tropics. Further, evolution of modern order of mammals near the PETM has been recorded in many northern continents; however, the response of mammals in the tropics to these warming events is unknown. A tropical terrestrial record of these hyperthermal/CIE events, encompassing the earliest modern order mammal bearing horizon from India, can therefore be vital in understanding climatic and biotic evolution during the earliest Cenozoic time. Here, for the first time, we report high resolution carbon isotope ( δ 13C) stratigraphy, nannofossil, and Sr isotope ratio of marine fossil carbonate from the Cambay Shale Formation of Western India. The record shows complete preservation of all the above CIE events, including the PETM, hitherto unknown from the equatorial terrestrial records. δ 13C chemostratigraphy further suggests that at least the present early Eocene mammal-bearing horizon, recently discovered at Vastan, does not support the `out of India' hypothesis of earliest appearance of modern mammals and subsequent dispersal to the Holarctic continents.

  2. Late Paleocene–early Eocene carbon isotope stratigraphy from a near-terrestrial tropical section and antiquity of Indian mammals

    A Samanta; A Sarkar; M K Bera; Jyotsana Rai; S S Rathore

    2013-02-01

    Late Paleocene to early Eocene (∼56 to 51 Ma) interval is characterized by five distinct transient warming (hyperthermal) events (Paleocene–Eocene thermal maximum (PETM), H1/ETM2/ELMO, H2, I1 and I2) in a super greenhouse globe associated with negative carbon isotope excursions (CIEs). Although well-documented marine records exist at different latitudes, terrestrial PETM sections are rare. In particular, almost no terrestrial records of either the PETM or early Eocene hyperthermals (EEHs) are yet available from the tropics. Further, evolution of modern order of mammals near the PETM has been recorded in many northern continents; however, the response of mammals in the tropics to these warming events is unknown. A tropical terrestrial record of these hyperthermal/CIE events, encompassing the earliest modern order mammal bearing horizon from India, can therefore be vital in understanding climatic and biotic evolution during the earliest Cenozoic time. Here, for the first time, we report high resolution carbon isotope (13C) stratigraphy, nannofossil, and Sr isotope ratio of marine fossil carbonate from the Cambay Shale Formation of Western India. The record shows complete preservation of all the above CIE events, including the PETM, hitherto unknown from the equatorial terrestrial records. 13C chemostratigraphy further suggests that at least the present early Eocene mammal-bearing horizon, recently discovered at Vastan, does not support the `out of India' hypothesis of earliest appearance of modern mammals and subsequent dispersal to the Holarctic continents.

  3. Aeolian stratigraphy and thermoluminescence dating of sediments of late Holocene age from Sola, southwest Norway

    Thermoluminescence age determinations were performed on four aeolian sand samples of late Holocene sediments from Stavanger airport, Sola, in southwest Norway. The locality is well suited for testing thermoluminescence dating because of a good agreement between radiocarbon ages and age information based on archaeological typology and sea level changes. The conclusion from a comparison of thermoluminescence and radiocarbon dates is that it is possible to date well bleached sediments as young as 1600 years with thermoluminescence. 57 refs., 7 figs., 6 tabs

  4. Late Pleistocene and Holocene palaeoflood events recorded by slackwater deposits in the upper Hanjiang River valley, China

    Liu, Tao; Huang, Chun Chang; Pang, Jiangli; Zha, Xiaochun; Zhou, Yali; Zhang, Yuzhu; Ji, Lin

    2015-10-01

    Slackwater palaeoflood deposits (SWDs) were identified in a bedrock gorge in the upper reaches of the Hanjiang River of central China. The Hanjiang River is the longest tributary of the Yangtze River, one of the most flood-prone rivers in China, and the main source of water for the South-to-North Water Transfer Project (SNWTP). Three main loess-soil profiles with late Pleistocene and Holocene palaeoflood SWD bedsets were found. Palaeoflood SWDs identified interbedded in the loess-soil sequence of late Pleistocene and Holocene age within the cliff riverbanks were studied by field observations and laboratory analysis, including particle-size distribution and Optically Stimulated Luminescence (OSL) dating. At least eight extreme flood events documented by palaeoflood SWDs occurred in the Wufeng reaches of the upper Hanjiang River. The discharge estimation associated with palaeoflood SWDs, indicates that the minimum flood peak discharges of these flood episodes range from 42,220 to 63,400 m3/s. The SWDs were OSL dated to between 12,600-12,400, 4200-4000, 3200-2800 and 1900-1700 a BP and these dates were corroborated with pottery remains retrieved from the profiles and dated by archaeological methods. These periods of increased flood magnitude coincide with contemporaneous global climatic events dated to 12,500, 4200, 3100 and 1900 a BP worldwide. These findings are of great significance in understanding the interactions between hydrological systems and climatic change in monsoonal zones.

  5. First record of fossil wood and phytolith assemblages of the Late Pleistocene in El Palmar National Park (Argentina)

    Zucol, A. F.; Brea, M.; Scopel, A.

    2005-10-01

    Two paleoxylologic assemblages and two phytolith assemblages were recovered from Late Pleistocene sediments of El Palmar Formation. These deposits are found in outcrops along the western margin of the Uruguay River. The spectra of taxa obtained in both sets by different methods is complementary. The fossil remains are characterized in terms of floristic composition and paleoclimate. Seven families are recognized: Podostemaceae, Myrtaceae, Anacardiaceae, Mimosoideae, Arecaceae, Poaceace, and Cyperaceae. Sponge siliceous spicules also have been found in these assemblages. The state of preservation of the phytoliths and their weathering degree is analyzed. These studies can be used as a potential paleoecological tool for alluvial sediments. The comparison of fossil assemblages with modern analogs clarifies the paleoecological requirements and composition of two paleocommunities, one dominated by woody forests and the other by palms. The climatic conditions inferred from the reconstructed vegetation and sedimentary deposits indicate a temperate-warm, humid climate. The results constitute the first evidence of the floral diversity of the vegetation in El Palmar National Park during the Late Pleistocene.

  6. Multi-proxy evidence for Late Pleistocene Holocene climatic and environmental changes in Lop-Nur, Xinjiang, Northwest China

    LUO Chao; YANG Dong; PENG Zicheng; ZHANG Zhaofeng; LIU Weiguo; HE Jianfeng; ZHOU Chenlin

    2008-01-01

    A 10.35-m-long sediment core from the Luobei depression in Lop-Nur, Xinjiang, Northwest China, provides detailed information about environmental changes during the Late Pleistocene. The samples taken every 5 cm of the core were unalyzed for 10 environmental proxies, including magnetic susceptibility, granularity, chroma, carbonate and loss on ignition (LOI), and pH value. The chronology data are provided by the uranium/thorium disequilibrium dates. The sediments of the section were deposited during the last 32000 years. The results of analysis of 10 proxies were examined using multivariate statistical analysis, and the principal components were calculated. According to the results, the Late Pleistocene sequence contains four climatic and environmental stages appearing in the cycles of cold-wet and warm-dry changes. During 10-9 ka BP, it was the earliest warm episode in the Holocene.Environmental changes in this district were restricted by global change, as suggested by the analysis of glacial-interglacial cycles. But it was different from the mutative trend of a monsoon region in East China because of its own characteristics, which was the situation of cold-wet and warm-dry climate-environment change. The candidate reason may be the uplift of the Tibet Plateau and the westerly wind circulation.

  7. Differential resilience of ancient sister lakes Ohrid and Prespa to environmental disturbances during the Late Pleistocene

    E. Jovanovska

    2015-09-01

    Full Text Available Ancient lakes, like lakes Ohrid and Prespa on the Balkan Peninsula, have become model systems for studying the link between geological and biotic evolution. Recently the scientific deep drilling program "Scientific Collaboration on Past Speciation Conditions in Lake Ohrid" (SCOPSCO has been launched to better understand the environmental, climatic and limnological evolution of the lake. It revealed that Lake Ohrid experienced a number of environmental disturbances during its ca. 2.0 million year long history. They comprise disturbances that lasted over longer periods of times ("press events" such as Heinrich events as well as sudden and short disturbances ("pulse events" like the deposition of volcanic ashes. The latter include one of the most severe volcanic episodes during the Late Pleistocene, the eruption of the Campanian Ignimbrite (known as Y-5 marine tephra layer from the Campi Flegrei caldera, dated at 39.6 ± 0.1 ka ago. The event is recorded by the deposition of a ca. 15 cm thick Y-5 tephra layer in sediment cores of lakes Ohrid (DEEP-5045-1 and Prespa (Co1204. This pulse event is overlain by the Heinrich event 4 (H4, 40.0–38.0 ka ago. In the current paper, diatoms were used as proxies to compare the responses of these lakes to the Y-5 (pulse and the H4 (press disturbances. Based on stratigraphically constrained incremental sum of squares cluster (CONISS and unconstrained Partitioning Around Medoids (PAM analyses, we found only little evidence that the diatom community compositions in either lake responded to the H4 event. However, the Y-5 influx caused clear and rapid diatom community changes. After the initial response, community composition in Lake Ohrid and, to a lesser extent, in Lake Prespa slowly returned to their quasi pre-disturbance state. Moreover, there is no evidence for disturbance-related extinction events. The combined evidence from these findings suggests that lakes Ohrid and Prespa likely did not experience regime

  8. Differential resilience of ancient sister lakes Ohrid and Prespa to environmental disturbances during the Late Pleistocene

    Jovanovska, E.; Cvetkoska, A.; Hauffe, T.; Levkov, Z.; Wagner, B.; Sulpizio, R.; Francke, A.; Albrecht, C.; Wilke, T.

    2015-09-01

    Ancient lakes, like lakes Ohrid and Prespa on the Balkan Peninsula, have become model systems for studying the link between geological and biotic evolution. Recently the scientific deep drilling program "Scientific Collaboration on Past Speciation Conditions in Lake Ohrid" (SCOPSCO) has been launched to better understand the environmental, climatic and limnological evolution of the lake. It revealed that Lake Ohrid experienced a number of environmental disturbances during its ca. 2.0 million year long history. They comprise disturbances that lasted over longer periods of times ("press events") such as Heinrich events as well as sudden and short disturbances ("pulse events") like the deposition of volcanic ashes. The latter include one of the most severe volcanic episodes during the Late Pleistocene, the eruption of the Campanian Ignimbrite (known as Y-5 marine tephra layer) from the Campi Flegrei caldera, dated at 39.6 ± 0.1 ka ago. The event is recorded by the deposition of a ca. 15 cm thick Y-5 tephra layer in sediment cores of lakes Ohrid (DEEP-5045-1) and Prespa (Co1204). This pulse event is overlain by the Heinrich event 4 (H4), 40.0-38.0 ka ago. In the current paper, diatoms were used as proxies to compare the responses of these lakes to the Y-5 (pulse) and the H4 (press) disturbances. Based on stratigraphically constrained incremental sum of squares cluster (CONISS) and unconstrained Partitioning Around Medoids (PAM) analyses, we found only little evidence that the diatom community compositions in either lake responded to the H4 event. However, the Y-5 influx caused clear and rapid diatom community changes. After the initial response, community composition in Lake Ohrid and, to a lesser extent, in Lake Prespa slowly returned to their quasi pre-disturbance state. Moreover, there is no evidence for disturbance-related extinction events. The combined evidence from these findings suggests that lakes Ohrid and Prespa likely did not experience regime shifts. It

  9. A 10Be Chronology of Late Pleistocene and Holocene Glaciation in the Rwenzori Mountains, Uganda

    Baber, M.; Kelly, M. A.; Russell, J. M.; Loomis, S. E.

    2012-12-01

    Although the retreat of glaciers in East Africa has been monitored over the last century, longer-term records of African glacier fluctuations are scarce. The Rwenzori Mountains, located on the border of Uganda and the Democratic Republic of Congo, host the largest glacial system in Africa and provide an opportunity for extensive investigation of past glaciations. We mapped and applied surface exposure (10Be) dating to glacial moraines deposited since the end of the last ice age in the Rwenzori Mountains to test the feasibility of 10Be dating at this site and to develop a chronology of glacial fluctuations. Our study is the first to use 10Be dating of glacial features in Africa and is possible because the Rwenzori host quartz-rich lithologies. By comparing the timing of Rwenzori glacial advances with other paleoclimate records from East Africa, we also will examine the climatic conditions which influenced tropical glacier fluctuations. Osmaston (1989) mapped moraines in the Rwenzori Mountains, documenting three stages of Pleistocene and Holocene glaciations, the Mahoma, Omurubaho and Lac Gris stages. The Mahoma stage moraines are estimated to be older than 17,980 ± 780 yr BP (D. M. Livingstone, 1962) by basal 14C dating of sediments from Lake Mahoma, situated in large lateral moraine at 2990 m asl. The age of the Omurubaho stage moraine is estimated from a basal 14C age (7,730 ± 150 yr BP) Lower Kitandara Lake (3990 m asl) and dammed by an Omurubaho stage moraine. The Lac Gris moraines are estimated at ~150-700 yr BP (de Heinzelin, 1953; Bergström, 1955) based on rates of lichen growth and plant colonization on moraines about 200 m below current glacial positions on Mt. Stanley. Though considerable uncertainty remains for the ages of these glacier deposits, these three stages most likely represent ages from the LGM to the LIA. We present two new 10Be ages of boulders from two moraines in the Nyamagusani Valley, ~4000 m asl. Sample KOP-2 (4033 m asl) is from the

  10. Late Pleistocene and Holocene aeolian sedimentation in Gonghe Basin, northeastern Qinghai-Tibetan Plateau: Variability, processes, and climatic implications

    Qiang, Mingrui; Jin, Yanxiang; Liu, Xingxing; Song, Lei; Li, Hao; Li, Fengshan; Chen, Fahu

    2016-01-01

    Although stratigraphic sequences of aeolian deposits in dryland areas have long been recognized as providing information about past environments, the exact nature of the environmental processes they reflect remains unclear. Here, we report the results of a detailed investigation of eight outcrop sections in the Gonghe Basin, northeastern Qinghai-Tibetan Plateau. Measurements of sediment grain-size and chemical composition indicate that the deposits are primarily of aeolian origin, consisting of interbedded, well-sorted sand, silty sand, loess and/or palaeosol; however, their occurrence varies from site to site. Fossil dune sands mainly occur in or close to the currently stabilized or semi-stabilized dune fields, whereas loess is distributed along the downwind marginal areas. This pattern of basin-scale differentiation was controlled mainly by spatial variability of sediment supply due to the antecedent sedimentary patterns within the basin. Together with previously-published optically stimulated luminescence (OSL) ages, 24 new OSL dates are used to elucidate the history of aeolian activity and its relationship to climatic changes. There is no apparent relationship between past dune activity and downwind loess deposits. Deposition of silty sand probably occurred during past phases of windy, dry and cold climate in the Late Pleistocene. However, climatic factors alone cannot explain the occurrence of silty sand deposition. This is because the deposition of silty sand was always preceded by episodes of fluvial deposition prior to river incision, thereby indicating the importance of an 'activated' sediment supply associated with fluvial processes. Deposition of well-sorted sand occurred episodically, not only during the Late Pleistocene, but also during the early- to mid-Holocene. Vegetation conditions, controlled either by the occurrence of intervals of moisture deficit during the Late Pleistocene or by changes in the balance between precipitation and

  11. Late Pliocene and Early Pleistocene vegetation history of northeastern Russian Arctic inferred from the Lake El'gygytgyn pollen record

    Andreev, A. A.; Tarasov, P. E.; Wennrich, V.; Raschke, E.; Herzschuh, U.; Nowaczyk, N. R.; Brigham-Grette, J.; Melles, M.

    2014-05-01

    The 318 m thick lacustrine sediment record from Lake El'gygytgyn, northeastern Russian Arctic cored by the international El'gygytgyn Drilling Project provides unique opportunities for the time-continuous reconstruction of the regional paleoenvironmental history for the past 3.6 Myr. Pollen studies of the lower 216 m of the lacustrine sediments demonstrate their value as an excellent archive of vegetation and climate changes during the Late Pliocene and Early Pleistocene. About 3.5-3.35 Myr BP, the vegetation at Lake El'gygytgyn, now an area of tundra was dominated by spruce-larch-fir-hemlock forests. After ca. 3.35 Myr BP dark coniferous taxa gradually disappeared. A very pronounced environmental change took place ca. 3.31-3.28 Myr BP, corresponding to the Marine Isotope Stage (MIS) M2, when treeless tundra- and steppe-like habitats became dominant in the regional vegetation. Climate conditions were similar to those of Late Pleistocene cold intervals. Numerous coprophilous fungi spores identified in the pollen samples suggest the presence of grazing animals around the lake. Following the MIS M2 event, larch-pine forests with some spruce mostly dominated the area until ca. 2.6 Myr BP, interrupted by colder and drier intervals ca. 3.043-3.025, 2.935-2.912, and 2.719-2.698 Myr BP. At the beginning of the Pleistocene, ca. 2.6 Myr BP, noticeable climatic deterioration occurred. Forested habitats changed to predominantly treeless and shrubby environments, which reflect a relatively cold and dry climate. Peaks in observed green algae colonies (Botryococcus) around 2.53, 2.45, 2.32-2.305, 2.20 and 2.16-2.15 Myr BP suggest a spread of shallow water environments. A few intervals (i.e., 2.55-2.53, ca. 2.37, and 2.35-2.32 Myr BP) with a higher presence of coniferous taxa (mostly pine and larch) document some relatively short-term climate ameliorations during Early Pleistocene glacial periods.

  12. THE LATE EARLY PLEISTOCENE HUMAN REMAINS FROM BUIA, DANAKIL DEPRESSION, ERITREA

    ROBERTO MACCHIARELLI

    2004-12-01

    Full Text Available The Early Pleistocene sedimentary succession of the Dandiero (Buia Basin (Danakil Depression, Eritrea has preserved a rich paleontological, paleoanthropological, and archeological record. Fieldwork undertaken between 1995 and 2003 on a site at Uadi Aalad (Abbate et al. 1998 led to the discovery of one-million-year-old human remains. They consist of a cranium in excellent preservation condition (UA-31, two permanent teeth (UA-222 and UA-369, and three pelvic portions (UA-173, UA-405 and UA-466, the latter recovered on 2003. The cranium and the postcranial remains represent a single adult individual, likely of female sex. The cranium evidences a blend of "erectus-like" and progressive morpho-architectural features, the latter more commonly found in the Middle Pleistocene. Preparation and restoration of the specimens (notably, of the virtually complete UA-31 face were only completed on September 2003. The revision, refinement, and integration of our previous analytical and interpretative work (cf. Abbate et al. 1998; Macchiarelli et al. 2002 is in progress within the context of the paleoanthropological reord currently available for the African Early to Middle Pleistocene.

  13. Late Quaternary stratigraphy, sedimentology, and geochemistry of an underfilled lake basin in the Puna (north-west Argentina)

    McGlue, Michael M.; Cohen, Andrew S.; Ellis, Geoffrey S.; Kowler, Andrew L.

    2013-01-01

    Depositional models of ancient lakes in thin-skinned retroarc foreland basins rarely benefit from appropriate Quaternary analogues. To address this, we present new stratigraphic, sedimentological and geochemical analyses of four radiocarbon-dated sediment cores from the Pozuelos Basin (PB; northwest Argentina) that capture the evolution of this low-accommodation Puna basin over the past ca. 43 cal kyr. Strata from the PB are interpreted as accumulations of a highly variable, underfilled lake system represented by lake-plain/littoral, profundal, palustrine, saline lake and playa facies associations. The vertical stacking of facies is asymmetric, with transgressive and thin organic-rich highstand deposits underlying thicker, organic-poor regressive deposits. The major controls on depositional architecture and basin palaeogeography are tectonics and climate. Accommodation space was derived from piggyback basin-forming flexural subsidence and Miocene-Quaternary normal faulting associated with incorporation of the basin into the Andean hinterland. Sediment and water supply was modulated by variability in the South American summer monsoon, and perennial lake deposits correlate in time with several well-known late Pleistocene wet periods on the Altiplano/Puna plateau. Our results shed new light on lake expansion–contraction dynamics in the PB in particular and provide a deeper understanding of Puna basin lakes in general.

  14. Aeolian to shallow-marine shelf architecture off a major desert since the Late Pleistocene (northern Mauritania)

    Hanebuth, T. J. J.; Mersmeyer, H.; Kudrass, H. R.; Westphal, H.

    2013-12-01

    Continental shelves off major desert regions are not expected to host substantial amounts of sediments due to long-lasting and unfocused material supply and a high re-mobilization potential of aeolian material. This study, in contrast, demonstrates that significant volumes of sediments have accumulated on the northern Mauritanian shelf under the arid climate conditions and prevail over consecutive climatic cycles. Eight late Pleistocene to Holocene depositional units, each formed under contrasting depositional conditions, are identified in high-resolution seismo-acoustic data and dated sediment cores. These are: (1) a highly differentiated Pleistocene paleo-landscape older than the past climatic cycle, (2) a continental dune complex (MIS-4), (3) a thick regressive shallow-water clinoform (late MIS-3), (4) a regressive to lowstand shore deposit (latest MIS-3), and (5) a local transgressive cover (LGM to deglacial). Additionally, (6) an open-shelf highstand cover, (7) an outer-shelf highstand wedge and (8) mid-shelf mud depocenters have formed during the Holocene sea-level highstand. The common local offshore formation and preservation of confined stratigraphic units, in particular from during MIS-3, mark the interplay of: a) episodes of pronounced arid climatic conditions resulting in enhanced aeolian and coastal sediment input, b) shelf current patterns focusing sediment deposition locally, and c) early post-depositional sediment stabilization providing protection against erosion. Prominent internal surfaces at 63 and 115 m modern water depths indicate widespread and intense erosional activity during late MIS-3 regression and MIS-2 lowstand to post-LGM transgression, hosting coarse shell sands and gravels from beach and shoreface paleo-environments. The reasons for the high preservation potential of confined stratigraphic units are: a) carbonaceous cementation, b) sediment composition (massive widespread shore-related gravel and shell beds with subtle minor

  15. Age, Stratigraphy, and Correlations of the Late Neogene Purisima Formation, Central California Coast Ranges

    Powell, Charles L.; Barron, John A.; Sarna-Wojcicki, Andrei M.; Clark, Joseph C.; Perry, Frank A.; Brabb, Earl E.; Fleck, Robert J.

    2007-01-01

    The Purisima Formation is an important upper Miocene and Pliocene stratigraphic unit in central California, cropping out from the coast at Point Reyes north of San Francisco to more extensive exposures in the Santa Cruz Mountains to the south. The fine-grained rocks in the lower parts of the Purisima Formation record a latest Miocene transgressive event, whereas the middle and upper parts of the formation consist of increasingly clastic-rich siltstones and sandstones resulting from uplift of adjacent coastal regions and the Sierra Nevada during Pliocene transgressive and regressive sea-level events. Exposures of the Purisima occur in three different, fault-bounded, structural blocks - the Santa Cruz, Pigeon Point, and Point Reyes tectonic blocks - that complicate correlations and regional age assignments. We summarize and compare published and new biostratigraphic and geochronologic data for various exposures of the Purisima Formation on the basis of mollusks, diatoms, radiometric dating, magnetostratigraphy, tephrochronology, and strontium isotope dating. On the basis of these data, we conclude that the Purisima Formation ranges in age from the latest Miocene (about 7 Ma) to the late Pliocene (about 2.6 Ma). The Purisima Formation of Santa Cruz County, exposed in the sea cliffs from Santa Cruz to Rio del Mar, is here designated a supplementary reference section because it is the most complete and well studied Purisima section in central California.

  16. Late Holocene stratigraphy of coastal deposits between Auckland and Dunedin, New Zealand

    Three chronostratigraphic units based on accumulative deposits and their respective soils are proposed for late Holocene coastal deposits between Auckland and Dunedin, New Zealand: Tamatean Chronozone (c. 1,800 to 450 years BP), Ohuan Chronozone (c. 450 to 150 years BP), and Hoatan Chronozone (c. 150 years to present day). The chronozones represent depositional episodes each consisting of two phases: a high rate of deposition (unstable phase), followed by a low rate of deposition and soil formation (stable phase). Vegetation on soils formed during the stable phases is inferred principally from landsnails recovered from archaeological sites. Forest on Tamatean soil (600 to 450 years BP) advanced almost to the coast in the Manawatu, the southeast Wairarapa, and on the East Coast. Sediment thickness measured at sections along the eastern North Island coast show that rates of deposition during unstable phases have decreased during the last 650 years. The depositional episodes appear to be unrelated to sea level changes, tectonic activity, volcanic eruptions or cultural influence. Unstable phases appear to correlate with times of high temperatures, and stable phases with time of low temperatures; it is suggested that the episodes may be related to changes in the frequency of tropical and extratropical cyclones. Inferred climate during unstable phases is windy and dry, and during stable phases, less windy and moist

  17. Late Quaternary paleosols, stratigraphy and landscape evolution in the Northern Pampa, Argentina

    Kemp, Rob A.; Zárate, Marcelo; Toms, Phillip; King, Matthew; Sanabria, Jorge; Arguello, Graciella

    2006-07-01

    The field properties, micromorphology, grain-size, geochemistry, and optically stimulated luminescence (OSL) ages of two late Quaternary sections have been used to reconstruct the sequence of pedosedimentary processes and to provide insights into landscape evolution in part of the Northern Pampa of Argentina. Paleosols developed in paludal sediments adjacent to the Paraná river at Baradero and in loess at Lozada can both be correlated and linked to other sites, thus enabling for the first time the tentative recognition and tracing of a diachronous soil stratigraphic unit that probably spans the equivalent of at least part of marine oxygen isotope stage (OIS) 5. The paleosol at Lozada was truncated and buried beneath fluvial sediments during the time span of OIS 4 and 3. Eolian gradually replaced paludal inputs at Baradero over this period, and there were also two clearly defined breaks in sedimentation and development of paleosols. The period corresponding to OIS 2 was marked by significant loess accumulation at both sites with accretion continuing into the mid-Holocene only at Lozada. The more developed nature of the surface soil at Baradero probably reflects a combination of a moister climate and a longer soil-forming interval.

  18. Prehistoric Earthquakes in the Chishan Segment of the Tancheng- Lujiang Fault Zone during the Mid-Late Pleistocene

    Yao Daquan; Tang Youbiao; Shen Xiaoqi; Chen Anguo; Zheng Haigang; Zhao Peng; XiaoWeipeng; Li Guang; Zheng Yinping; Li Lingli

    2012-01-01

    Chishan is located in Sixian County of Anhui Province, and the west branch fault of Tancheng-Lujiang fault zone passes through here. According to previous research, the Chishan segment of Tancheng-Lujiang fault zone has been obviously active since the Quaternary. Trenches excavated perpendicular to the Chishan segment for this study have revealed many prehistoric earthquake ruins--the multi-phase reverse faulting colluvial wedge, which is represented as the western brick-red sandstone of the late Cretaceous or maize gravel stratum of the mid Pleistocene of the hanging wall of the fault overlapping eastward the mid-late Pleistocene brown clay. In the base of the wedges, steep NW-dipping faults were found, and the steep fault planes turned upward to gently dipping collapse planes. As revealed by the trenches, the connection line of the breaking points strikes NNE in general. Heaving landforms are preserved at most parts of the tailing edge of the hanging wall where the fault passes through, and some EW-trending gullies were offset by right- lateral faulting. The two walls of several trenches have consistently shown that the collapse of traces have been pushed by a west-to-east force. Among them, Tcl - Tc4 show that the brick red limestone (K2 ) overthrust and collapsed on the yellow-brown clay containing ferro-manganese nodules ( Q2r-3 ) ; Tc5 reveals that the yellowish-white gravel ( Q2r ) and the sandstone (K2 ) and overthrust and collapsed on the aforementioned clay. Reverse faulting colluvial wedges are found on both walls of each of the 8 trenches, but the number of wedges revealed in different trenches is different: there is 1 wedge, and 2 wedges in Tcl and Tc3. 3 wedges in Tc2, Tc4 and Tc5, and in individual trenches, few wedges are revealed. This may be related to the trench's location, depth and height of theremaining denudation. From the analysis of the trenches and the thermoluminescence dating results, we can preliminarily conclude that multiple large

  19. Late ordovician stratigraphy, zircon provenance and tectonics, Lachlan Fold Belt, southeastern Australia

    Ordovician quartz turbidites of the Lachlan Fold Belt in southeastern Australia accumulated in a marginal sea and overlapped an adjoining island arc (Molong volcanic province) developed adjacent to eastern Gondwana. The turbidite succession in the Shoalhaven River Gorge, in the southern highlands of New South Wales, has abundant outcrop and graptolite sites. The succession consists of, from the base up, a unit of mainly thick-bedded turbidites (undifferentiated Adaminaby Group), a unit with conspicuous bedded chert (Numeralla Chert), a unit with common thin-bedded turbidites [Bumballa Formation (new name)] and a unit of black shale (Warbisco Shale). Coarse to very coarse sandstone in the Bumballa Formation is rich in quartz and similar to sandstone in the undifferentiated Adaminaby Group. Detrital zircons from sandstone in the Bumballa Formation, and from sandstone at a similar stratigraphic level from the upper Adaminaby Group of the Genoa River area in eastern Victoria, include grains as young as 453-473 Ma, slightly older than the stratigraphic ages. The dominant detrital ages are in the interval 500-700 Ma (Pacific Gondwana component) with a lessor concentration of Grenville ages (1000-1300 Ma). This pattern resembles other Ordovician sandstones from the Lachlan Fold Belt and also occurs in Triassic sandstones and Quaternary sands from eastern Australia. The Upper Ordovician succession is predominantly fine grained, which reflects reduced clastic inputs from the source in the Middle Cambrian to earliest Ordovician Ross-Delamerian Fold Belts that developed along the eastern active margin of Gondwana. Development of subduction zones in the Late Ordovician marginal sea are considered to be mainly responsible for the diversion of sediment and the resulting reduction in the supply of terrigenous sand to the island arc and eastern part of the marginal sea. Sixty zircons from each sample were analysed and results are presented. Methods following standard procedures

  20. Didelphidae marsupials (Mammalia, Didelphimorphia) from the late Pleistocene deposit of the Gruta dos Moura Cave, northern Brazil.

    Nova, Patricia Villa; Avilla, Leonardo S; Oliveira, Édison V

    2015-03-01

    The present study acknowledges the diversity of fossil marsupials from the Gruta dos Moura cave, as well as environmental and climatic aspects during the Quaternary. The results show that this is the largest diversity of Pleistocene marsupials recorded in a single cave: Didelphis albiventris, D. aurita, Gracilinanus agilis, G. microtarsus, Marmosa murina, Monodelphis brevicaudata, M. domestica and Sairadelphys tocantinensis. Furthermore, the described specimens are also part of the only fossil assemblage unequivocally referable to the late Pleistocene. Paleontological studies suggest an intimate association with dry and open environments with high abundance of water sources. Since most of the identified taxa are characteristic of open forests and gallery forests, this could represent the actual environment around the Gruta dos Moura cave. Recent studies identified sympatric occurrences between species from open and dry environments and species from humid forests that were identified among our material and are characteristic of humid regions. Therefore, these species could inhabit gallery forests and capons, or even ecotones, inside a dry and open environment. Moreover, the extinction of Sairadelphys could also indicate that the climatic and environmental conditions changed or that the past environment was more heterogeneous than the current environment of the region. PMID:25806985

  1. Assessing the impact of late Pleistocene megafaunal extinctions on global vegetation and climate

    Brault, M.-O.; Mysak, L. A.; Matthews, H. D.; Simmons, C. T.

    2013-08-01

    The end of the Pleistocene was a turning point for the Earth system as climate gradually emerged from millennia of severe glaciation in the Northern Hemisphere. The deglacial climate change coincided with an unprecedented decline in many species of Pleistocene megafauna, including the near-total eradication of the woolly mammoth. Due to an herbivorous diet that presumably involved large-scale tree grazing, the mammoth extinction has been associated with the rapid expansion of dwarf deciduous trees in Siberia and Beringia, thus potentially contributing to the changing climate of the period. In this study, we use the University of Victoria Earth System Climate Model (UVic ESCM) to simulate the possible effects of these extinctions on climate during the latest deglacial period. We have explored various hypothetical scenarios of forest expansion in the northern high latitudes, quantifying the biogeophysical effects in terms of changes in surface albedo and air temperature. These scenarios include a Maximum Impact Scenario (MIS) which simulates the greatest possible post-extinction reforestation in the model, and sensitivity tests which investigate the timing of extinction, the fraction of trees grazed by mammoths, and the southern extent of mammoth habitats. We also show the results of a simulation with free atmospheric CO2-carbon cycle interactions. For the MIS, we obtained a surface albedo increase and global warming of 0.006 and 0.175 °C, respectively. Less extreme scenarios produced smaller global mean temperature changes, though local warming in some locations exceeded 0.3 °C even in the more realistic extinction scenarios. In the free CO2 simulation, the biogeophysical-induced warming was amplified by a biogeochemical effect, whereby the replacement of high-latitude tundra with shrub forest led to a release of soil carbon to the atmosphere and a small atmospheric CO2 increase. Overall, our results suggest the potential for a small, though non-trivial, effect of

  2. Assessing the impact of late Pleistocene megafaunal extinctions on global vegetation and climate

    M.-O. Brault

    2013-08-01

    Full Text Available The end of the Pleistocene was a turning point for the Earth system as climate gradually emerged from millennia of severe glaciation in the Northern Hemisphere. The deglacial climate change coincided with an unprecedented decline in many species of Pleistocene megafauna, including the near-total eradication of the woolly mammoth. Due to an herbivorous diet that presumably involved large-scale tree grazing, the mammoth extinction has been associated with the rapid expansion of dwarf deciduous trees in Siberia and Beringia, thus potentially contributing to the changing climate of the period. In this study, we use the University of Victoria Earth System Climate Model (UVic ESCM to simulate the possible effects of these extinctions on climate during the latest deglacial period. We have explored various hypothetical scenarios of forest expansion in the northern high latitudes, quantifying the biogeophysical effects in terms of changes in surface albedo and air temperature. These scenarios include a Maximum Impact Scenario (MIS which simulates the greatest possible post-extinction reforestation in the model, and sensitivity tests which investigate the timing of extinction, the fraction of trees grazed by mammoths, and the southern extent of mammoth habitats. We also show the results of a simulation with free atmospheric CO2-carbon cycle interactions. For the MIS, we obtained a surface albedo increase and global warming of 0.006 and 0.175 °C, respectively. Less extreme scenarios produced smaller global mean temperature changes, though local warming in some locations exceeded 0.3 °C even in the more realistic extinction scenarios. In the free CO2 simulation, the biogeophysical-induced warming was amplified by a biogeochemical effect, whereby the replacement of high-latitude tundra with shrub forest led to a release of soil carbon to the atmosphere and a small atmospheric CO2 increase. Overall, our results suggest the potential for a small, though non

  3. Geographic and temporal trends in proboscidean and human radiocarbon histories during the late Pleistocene

    Ugan, Andrew; Byers, David

    2007-12-01

    The causes of large animal extinctions at the end of the Pleistocene remain a hotly debated topic focused primarily on the effects of human over hunting and climate change. Here we examine multiple, large radiocarbon data sets for humans and extinct proboscideans and explore how variation in their temporal and geographic distributions were related prior to proboscidean extinction. These data include 4532 archaeological determinations from Europe and Siberia and 1177 mammoth and mastodont determinations from Europe, Siberia, and North America. All span the period from 45,000 to 12,000 calendar years BP. We show that while the geographic ranges of dated human occupations and proboscidean remains overlap across the terminal Pleistocene of the Old World, the two groups remain largely segregated and increases in the frequency of human occupations do not coincide with declines in proboscidean remains. Prior to the Last Glacial Maximum (LGM; ca 21,000 years BP), archaeological 14C determinations increase slightly in frequency worldwide while the frequency of dated proboscidean remains varies depending on taxon and location. After the LGM, both sympatric and allopatric groups of humans and proboscideans increase sharply as climatic conditions ameliorate. Post-LGM radiocarbon frequencies among proboscideans peak at different times, also depending upon taxon and location. Woolly mammoths in Beringia reach a maximum and then decline beginning between 16,000 and 15,500 years BP, woolly mammoths in Europe and Siberia ca 14,500 and 13,500 BP, and Columbian mammoth and American mastodont only after 13,000 BP. Declines among woolly mammoths appear to coincide with the restructuring of biotic communities following the Pleistocene-Holocene transition.

  4. The Late Holocene to Pleistocene tephrostratigraphic record of Lake Ohrid (Albania)

    Caron, Benoît; Sulpizio, Roberto; Zanchetta, Giovanni; Siani, Giuseppe; Santacroce, Roberto

    2010-06-01

    We present in this work a tephrostratigraphic record from a sediment piston core (JO 2004) from Lake Ohrid. Five tephra layers were recognised, all from explosive eruptions of southern Italy volcanoes. A multidisciplinary study was carried out, including stratigraphy, AMS 14C chronology and geochemistry. The five tephra layers were correlated with terrestrial proximal counterparts and with both marine and lacustrine tephra layers already known in the central Mediterranean area. The oldest is from Pantelleria Island (P11, 131 ka BP). Other three tephra layers are from Campanian volcanoes: X6, Campanian Ignimbrite-Y5 and SMP1-Y3 (107, 39 and 31 ka BP respectively). The youngest tephra layer corresponds to the FL eruption from Etna Volcano (3.4 ka BP). In three cases these recognitions confirm previous findings in the Balkans, while two of them were for the first time recognised in the area, with a significant enlargement of the previous assessed dispersal areas.

  5. Late Pleistocene to Holocene soil development and environments in the Long Gang Volcanic Field area, Jilin Province, NE China

    Sauer, Daniela; Zhang, Xinrong; Knöbel, Jette; Maerker, Lutz

    2014-05-01

    Late Pleistocene to Holocene shifts of climate and vegetation in the Long Gang Volcanic Field in NE China have been reconstructed, e. g. by Steblich et al. (2009), based on Maar lake sediment cores. In this study, we investigated soil development during the Late Pleistocene and Holocene and linked it to the climate and vegetation reported in the literature. Three pedons were described and analyzed on a crater wall surrounding a maar. The lower part of the slope is covered by basic pyroclastics that are obviously younger than the maar itself. Pedon 1 is located on the upper slope, where the younger pyroclastics are not present; thus it developed over the entire Holocene and part of the Late Pleistocene. Pedon 2 is on the toe slope and developed from the young basic pyroclastics. Vegetation remains, charred by fire that was caused by the volcanic ash fall, were found in the lowermost part of the pyroclastics layer, on top of a paleosol. Charcoal fragments were dated to 18950-18830 cal BP (using INTCAL 09). Thus, pedon 2 developed since around 18.9 ka BP, whereas the development of the paleosol that was buried under the pyroclastics (pedon 3), was stopped at this time. Pedons 1 and 2 are Vitric Andosols, developed mainly from basic pyroclastics, as evidenced by the composition of rock fragments in the soils, comprising 78 / 81 mass % lapilli and 22 / 19 mass % gneiss fragments, respectively. Pedon 3 is a Cutanic Luvisol (Chromic) that developed entirely from gneiss fragments produced by the maar explosion. Lab data suggest increasing intensity of pedogenesis in the direction: Pedon 3 (paleosol) characterized by reddish-brown color (7.5YR), strong angular blocky structure and well-expressed illuvial clay coatings, rather indicates that it developed over a longer time-span and/or warmer climate than the two yellowish-brown surface soils. Since the morphology of the paleosol clearly reflects interglacial climatic conditions and forest cover, it most likely started

  6. Late Pleistocene and Early Holocene Rock Art from the Mongolian Altai: The Material and its Cultural Implications

    Esther Jacobson-Tepfer

    2013-09-01

    Full Text Available Rock-pecked images from the northern Mongolian Altai attest to the presence of human communities within the high valleys of that region during the Late Pleistocene and Early Holocene. The material provides evidence that is hitherto largely missing from the archaeological record of that region. This paper reviews the rock art, its find sites and larger physical contexts and uses evidence from paleoenvironmental studies to propose dating and cultural significance. The material is compared with other sites said to have Paleolithic imagery from Mongolia and the adjoining Russian Altai. The body of presented material offers a major resource for the study of early hunter-gatherer communities at the interface of Central and North Asia.

  7. Co-occurrence of mylodontid sloths and insights on their potential distributions during the late Pleistocene

    Varela, Luciano; Fariña, Richard A.

    2016-01-01

    Species distribution models (SDMs) for the last interglacial (LIG), the global last glacial maximum (LGM) and the Holocene climatic optimum (HCO) were generated for three extinct South American Pleistocene mylodontid giant sloths, Glossotherium robustum, Lestodon armatus and Mylodon darwinii. They are recorded co-occurring in some localities including Arroyo del Vizcaíno site (AdV) in Uruguay. Co-occurrence records were studied based on the overlap of their generated areas of potential distributions, and compared with the available biome reconstructions of South America during the LGM to analyze their distribution patterns, ecological requirements and possible interactions between them. Our results suggest that these sloths could have co-existed mainly in the Chaco-Paraná Basin and the plains in the Río de la Plata area. Areas of high suitability were observed for submerged parts of the continental shelf that were exposed during the LGM showing an overall increase in potential habitat compared to the LIG and HCO. This suggests that there was a drastic reduction in total available areas of preferred habitat at the end of the Pleistocene. The co-occurrence of these sloths at the AdV site suggests the presence of vegetation indicative of mainly open, cold to temperate habitats but with mixed patches typical of humid climates.

  8. Orbital-driven environmental changes recorded at ODP Site 959 (eastern equatorial Atlantic) from the Late Miocene to the Early Pleistocene

    Vallé, Francesca; Westerhold, Thomas; Dupont, Lydie M.

    2016-06-01

    Palaeorecords from tropical environments are important to explore the linkages between precipitation, atmospheric circulation and orbital forcing. In this study, new high-resolution XRF data from ODP Site 959 (3°37'N, 2°44'W) have been used to investigate the relationship between palaeoenvironmental changes in West Africa and sedimentation in the tropical East Atlantic Ocean. Iron intensity data have been used to build a 91-m composite depth record that has been astronomically tuned allowing the development of a detailed age model from 6.2 to 1.8 Ma. Based on this new stratigraphy, we studied the variations of Ti/Al, Ti/Ca and Al/Si ratios, proxies for aeolian versus fluvial supply, as dust indicator and fine versus coarse grain size, respectively. We discuss sedimentation patterns at ODP Site 959 associated with the environmental changes from the late Miocene until the early Pleistocene. During the interval corresponding to the earlier stages of the Messinian Salinity Crisis, our proxy records indicate enhanced run-off from the West African continent and major supply of fine material at ODP Site 959, suggesting a stronger monsoon and increased precipitation during eccentricity minima. A long-term decrease of river supply is documented after 5.4 Ma until the end of the Pliocene. From the increased values and variability of Ti/Al and Ti/Ca ratios, we suggest that after 3.5 Ma dust started to reach the study site probably as a result of the southward shift of the Intertropical Convergence Zone during winter. Between 3.2 and 2.9 Ma, ODP Site 959 Ti/Ca ratios exhibit three maxima corresponding to eccentricity maxima similarly to other dust records of northern Africa. This suggests continent-wide aridity or larger climate variability during that interval. Eccentricity forcing (405 and 100 kyr) and precession frequencies are found in the entire studied interval. The variations of Ti/Al ratio suggest stronger seasonality between 5.8 and 5.5 Ma and after 3.2 Ma.

  9. Structure, formation and geochronology of the late Pleistocene and Holocene cover deposits in South-Eastern Lithuania

    Baltrūnas, Valentinas; Karmaza, Bronislavas; Molodkov, Anatoly; Šinkūnas, Petras; Švedas, Kęstutis; Zinkutė, Rimantė

    2010-11-01

    The available data of earlier investigations ( Basalykas, 1965; Basalykas et al., 1976a,b; Kudaba, 1983) show that deposits of various origin and age are widespread in Ašmena Upland and Lyda Plateau (South-Eastern Lithuania). They overlie a polygenetic dislodged marginal formations of the penultimate Medininkai (Warthe) glaciation. Pleistocene deposits in this area are often deformed by solifluction and fluvial erosion and penetrated by cryogenic ice-wedge pseudomorphs. Granulometric, geochemical and petrographic investigations of the deposits have demonstrated that they are characterized by different sources of sedimentary material supply as well as different degrees of physical and chemical weathering. The alternate deposits preserved in the study area imply palaeoenvironmental changes associated with the different palaeoclimatic events. The Ca/Zr ratios in cover deposits testify that the upper beds usually experienced stronger chemical weathering that is associated with warmer climate. The cases of weaker weathering can be explained by different sources of material, i.e. deposit origin, which can be indicated by Zr/Ti ratio. According to the scarce geochronological data available at least 4 clusters of IR-OSL dates can be distinguished in the late Pleistocene environmental history of Ašmena Upland and Lyda Plateau: about 100 ka (marine isotope stage (MIS) 5c, Merkinė interglacial), 89-71 ka (MIS 5a, Merkinė interglacial), about 40 ka (MIS 3, Rokai interstadial) and 21-12 ka (late Nemunas). One cluster of IR-OSL dates (9.7-5.3 ka) is obtained in the first half of Holocene.

  10. The three-quarter power scaling of extinction risk in Late Pleistocene mammals, and a new theory of the size selectivity of extinction

    Polishchuk, L.

    2010-01-01

    Questions: What is the pattern of body mass versus extinction risk in the Late Pleistocene extinctions of mammals, both qualitatively and quantitatively? Are there patterns that relate extinction risk to the well-known allometries of body mass with population density or population growth rate? Theor

  11. Leafcutter bee nests and pupae from the Rancho La Brea Tar Pits of southern California: Implications for understanding the paleoenvironment of the Late Pleistocene

    The Rancho La Brea Tar Pits is the world’s richest and most important Late Pleistocene fossil locality and best renowned for numerous fossil mammals and birds excavated over the past century. Less researched are insects, even though these specimens frequently serve as the most valuable paleoenvironm...

  12. Fossils in Late Cretaceous to early Palaeocene flint nodules embedded in pleistocene glaciofluvial sediments near Fukov (Děčín District, Northern Bohemia)

    Pokorný, R.; Kaše, J.; Kvaček, J.; Zágoršek, K.; Kočí, T.; Žítt, Jiří

    2012-01-01

    Roč. 68, 3/4 (2012), s. 119-131. ISSN 0036-5343 Institutional support: RVO:67985831 Keywords : Erratic boulders * Flint * Glaciofluvial sediments * Late Cretaceous * Northern Bohemia * Palaeocene * Pleistocene glaciation * Taphocoenosis Subject RIV: DB - Geology ; Mineralogy http://www.nm.cz/publikace/archiv.php?id=4&rok=68&kcislu=3-4&f_=Zobrazit

  13. Assessing the impact of late Pleistocene megafaunal extinctions on global vegetation and climate

    M.-O. Brault

    2013-01-01

    Full Text Available The end of the Pleistocene marked a turning point for the Earth system as climate gradually emerged from millennia of severe glaciation in the Northern Hemisphere. It is widely acknowledged that the deglacial climate change coincided with an unprecedented decline in many species of large terrestrial mammals, including the near-total eradication of the woolly mammoth. Due to an herbivorous diet that presumably involved large-scale tree grazing, the mammoth expansion would have accelerated the expansion of dwarf deciduous trees in Siberia and Beringia, thus contributing to the changing climate of the period. In this study, we use the University of Victoria Earth System Climate Model (UVic ESCM to simulate the possible effects of megafaunal extinctions on Pleistocene climate change. We have explored various hypothetical scenarios of forest expansion in the Northern Continents, quantifying the regional and global biogeophysical effects in terms of changes in surface albedo and air temperature. In particular, we focus our attention on a Maximum Impact Scenario (MIS which simulates the greatest possible post-extinction reforestation in the model. More realistic experiments include sensitivity tests based on the timing of extinction, the fraction of trees grazed by mammoths, and the size of mammoth habitats. We also show the results of a simulation with free (non-prescribed atmospheric CO2. For the MIS, we obtained a surface albedo increase of 0.006, which resulted in a global warming of 0.175 °C. Less extreme scenarios produced smaller global mean temperature changes, though local warming in some locations exceeded 0.3 °C even in the more realistic extinction scenarios. In the free CO2 simulation, the biogeophysical-induced warming was amplified by a biogeochemical effect whereby the replacement of high-latitude tundra with shrub forest led to a release of soil carbon to the atmosphere and a small atmospheric CO2

  14. From Cycles to Sequences: Sequence Stratigraphy and Relative Sea Level Change for the Late Cambrian of the North China Platform

    MEI Mingxiang; MA Yongsheng; DENG Jun; CHEN Huijun

    2005-01-01

    -order sequences is marked by "shallow ramp-tidal flat"; the sequence boundaries are characterized by exposure punctuated surfaces. According to the changes for the third-order sequences from the north to the south, a regular sequencestratigraphic framework can be established. From cycles to sequences, the study of sequence stratigraphy from litho-facies successions to sedimentary-facies successions exposes that as follows: meter-scale cycles that are used as the basic working unit actually are litho-facies successions formed by the mechanism of a punctuated aggradational cycle, and thirdorder sequences that are constituted by regularly vertical stacking patterns of meter-scale cycles are marked by sedimentary-facies successions. On the basis of the changing curve of water depth at each section, the curve of the relative third-order sea level changes in the late Cambrian of the North China Platform can be integrated qualitatively from changing curve of water depth. The correlation of Late Cambrian long-term sea level changes between North China and North America demonstrates that there are not only similarities but also differences, reflecting control of long-term sea level changes both by global eustacy and by regional factors.

  15. Climate-driven sediment aggradation and incision since the late Pleistocene in the NW Himalaya, India

    Dey, Saptarshi; Thiede, Rasmus C.; Schildgen, Taylor F.; Wittmann, Hella; Bookhagen, Bodo; Scherler, Dirk; Jain, Vikrant; Strecker, Manfred R.

    2016-09-01

    Deciphering the response of sediment routing systems to climatic forcing is fundamental for understanding the impacts of climate change on landscape evolution. In the Kangra Basin (northwest Sub-Himalaya, India), upper Pleistocene to Holocene alluvial fills and fluvial terraces record periodic fluctuations of sediment supply and transport capacity on timescales of 103 to 105 yr. To evaluate the potential influence of climate change on these fluctuations, we compare the timing of aggradation and incision phases recorded within remnant alluvial fans and terraces with climate archives. New surface-exposure dating of six terrace levels with in-situ cosmogenic 10Be indicates the onset of incision phases. Two terrace surfaces from the highest level (T1) sculpted into the oldest preserved alluvial fan (AF1) date back to 53.4 ± 3.2 ka and 43.0 ± 2.7 ka (1σ). T2 surfaces sculpted into the remnants of AF1 have exposure ages of 18.6 ± 1.2 ka and 15.3 ± 0.9 ka, while terraces sculpted into the upper Pleistocene-Holocene fan (AF2) provide ages of 9.3 ± 0.4 ka (T3), 7.1 ± 0.4 ka (T4), 5.2 ± 0.4 ka (T5) and 3.6 ± 0.2 ka (T6). Together with previously published OSL ages yielding the timing of aggradation, we find a correlation between variations in sediment transport with oxygen-isotope records from regions affected by the Indian Summer Monsoon. During periods of increased monsoon intensity and post-Last Glacial Maximum glacial retreat, aggradation occurred in the Kangra Basin, likely due to high sediment flux, whereas periods of weakened monsoon intensity or lower sediment supply coincide with incision.

  16. Compilation of information on the climate and evaluation of the hydrochemical and isotopic composition during Late Pleistocene and Holocene

    This report summarises and evaluates some of the existing information on the Late Pleistocene and Holocene climates, i.e. the last 130 000 years. An estimation of the conditions at the Aespoe island (southeast Sweden) has also been made during this time span. The knowledge about Late Pleistocene (Eemian Interglacial and Weichselian glacial) is not yet fully understood. There are still a lot of assumptions concerning this period and more information is needed to be able to establish the climatic conditions. This is not the case for the Weichselian deglaciation and the present interglacial, Holocene, for which the environmental conditions are quite certain. It has been concluded, however, that the Eemian climatic development probably was similar to the Holocene but perhaps somewhat warmer and more humid. The Eemian Baltic Sea level was probably also higher than the present Baltic Sea level and there was a connection between it and the White Sea in the northeast. Aespoe was probably situated below sea level during the greater part of Eemian. Not much is known about the last glacial period, the Weichselian glaciation, until the final deglaciation. The ice sheet during Early Weichselian was probably mostly concentrated to the Scandinavian mountain area and in northern Scandinavia. At least two intervals with higher temperatures have been recorded, the Broerup and Odderade interstadials. The Middle Weichselian substage is characterised by fluctuations, melting and re-advances. Aespoe was probably not glaciated until the middle or latter part of Middle Weichselian. The maximum extension of the Weichselian ice sheet occurred in Late Weichselian, around 20 to 18 ka BP, which was succeeded by the final deglaciation. The retreat of the Weichselian ice sheet is described by for example end moraines and glacial varved clay. The Aespoe area was glaciated until 12 500 BP. Huge quantities of glacial meltwater was released into the Baltic basin as the ice receded. Due to different

  17. Geomorphic and sedimentary responses of the Bull Creek Valley (Southern High Plains, USA) to Pleistocene and Holocene environmental change

    Arauza, Hanna M.; Simms, Alexander R.; Bement, Leland C.; Carter, Brian J.; Conley, Travis; Woldergauy, Ammanuel; Johnson, William C.; Jaiswal, Priyank

    2016-01-01

    Fluvial geomorphology and stratigraphy often reflect past environmental and climate conditions. This study examines the response of Bull Creek, a small ephemeral creek in the Oklahoma panhandle, to environmental conditions through the late Pleistocene and Holocene. Fluvial terraces were mapped and their stratigraphy and sedimentology documented throughout the course of the main valley. Based on their elevations, terraces were broadly grouped into a late-Pleistocene fill terrace (T3) and two Holocene fill-cut terrace sets (T2 and T1). Terrace systems are marked by similar stratigraphies recording the general environmental conditions of the time. Sedimentary sequences preserved in terrace fills record the transition from a perennial fluvial system during the late glacial period and the Younger Dryas to a semiarid environment dominated by loess accumulation and punctuated by flood events during the middle to late Holocene. The highest rates of aeolian accumulation within the valley occurred during the early to middle Holocene. Our data provide significant new information regarding the late-Pleistocene and Holocene environmental history for this region, located between the well-studied Southern and Central High Plains of North America.

  18. Late Pleistocene-Holocene events on the continental slope of the Laptev Sea: Evidence from benthic and planktonic foraminiferal assemblages

    Ovsepyan, Ya. S.; Taldenkova, E. E.; Bauch, H. A.; Kandiano, E. S.

    2015-11-01

    This work is dedicated to the study of benthic and planktonic foraminifers and is a contribution to the multidisciplinary investigations of Core PS51/154-11 from the Laptev Sea. The paleoecological analysis of foraminiferal assemblages makes it possible to reconstruct in detail environmental changes on the western continental margin of the Laptev Sea during the Late Pleistocene and Holocene. The examined core dated by the AMS radiocarbon method is divided into intervals that reflect main stages in the regional evolution for the last 17.6 k.y.: early deglaciation, Bølling-Allerød warming, Younger Dryas cooling, transition to the Interglacial, Holocene climatic optimum, Middle-Late Holocene. The presence of subpolar planktonic foraminifers and benthic species Cassidulina neoteretis (Tappan) provides grounds to reconstruct for the continental slope area stages of the enhanced activity of subsurface Atlantic-derived water in the intervals of 12.0-14.7 and 0.6-5.4 ka. The benthic assemblage reflects changes in depositional environments related to the postglacial transgression and also climatic change impacts affecting bioproductivity. The events defined on the basis of foraminifers are correlated with climatic oscillations and changes in circulation of water masses.

  19. Are Late-Pleistocene Climate Reconstructions from Cirque and Valley Moraines Possible in Regions of Decaying Ice Sheets?

    Menounos, B.; Goehring, B. M.; osborn, G.; Clague, J. J.; Davis, P. T.; Lakeman, T.; Schaefer, J. M.; Koch, J.; Clarke, G. K.

    2012-12-01

    many high alpine sites to become ice-free prior to cirque glacier growth during the YD. Conversely, in some valleys Cordilleran ice sheet outlet glaciers advanced in response to the YD to positions far beyond LIA limits. An implication of this study is that late Pleistocene climate reconstructions based on alpine moraines may be problematic in regions with decaying ice sheets. We are currently using numerical ice sheet models, forced with GCM simulations, to further examine the roles played by climatic and geomorphic factors on the spatial distribution of latest Pleistocene glaciers in western Canada and southernmost Patagonia.

  20. The late Early Pleistocene human dental remains from Uadi Aalad and Mulhuli-Amo (Buia), Eritrean Danakil: macromorphology and microstructure.

    Zanolli, Clément; Bondioli, Luca; Coppa, Alfredo; Dean, Christopher M; Bayle, Priscilla; Candilio, Francesca; Capuani, Silvia; Dreossi, Diego; Fiore, Ivana; Frayer, David W; Libsekal, Yosief; Mancini, Lucia; Rook, Lorenzo; Medin Tekle, Tsegai; Tuniz, Claudio; Macchiarelli, Roberto

    2014-09-01

    Fieldwork performed during the last 15 years in various Early Pleistocene East African sites has significantly enlarged the fossil record of Homo erectus sensu lato (s.l.). Additional evidence comes from the Danakil Depression of Eritrea, where over 200 late Early to early Middle Pleistocene sites have been identified within a ∼1000 m-thick sedimentary succession outcropping in the Dandiero Rift Basin, near Buia. Along with an adult cranium (UA 31), which displays a blend of H. erectus-like and derived morpho-architectural features and three pelvic remains, two isolated permanent incisors (UA 222 and UA 369) have also been recovered from the 1 Ma (millions of years ago) Homo-bearing outcrop of Uadi Aalad. Since 2010, our surveys have expanded to the nearby (4.7 km) site of Mulhuli-Amo (MA). This is a fossiliferous area that has been preliminarily surveyed because of its exceptional concentration of Acheulean stone tools. So far, the site has yielded 10 human remains, including the unworn crown of a lower permanent molar (MA 93). Using diverse analytical tools (including high resolution μCT and μMRI), we analysed the external and internal macromorphology and microstructure of the three specimens, and whenever possible compared the results with similar evidence from early Homo, H. erectus s.l., H. antecessor, H. heidelbergensis (from North Africa), Neanderthals and modern humans. We also assessed the UA 369 lower incisor from Uadi Aalad for root completion timing and showed that it compares well with data for root apex closure in modern human populations. PMID:24852385

  1. Late-Pleistocene evolution of the continental shelf of central Israel, a case study from Hadera

    Shtienberg, Gilad; Dix, Justin; Waldmann, Nicolas; Makovsky, Yizhaq; Golan, Arik; Sivan, Dorit

    2016-05-01

    Sea-level fluctuations are a dominant mechanism that control coastal environmental changes through time. This is especially the case for the successive regressions and transgressions over the last interglacial cycle, which have shaped the deposition, preservation and erosion patterns of unconsolidated sediments currently submerged on continental shelves. The current study focuses on creating an integrated marine and terrestrial geophysical and litho-stratigraphic framework of the coastal zone of Hadera, north-central Israel. This research presents a case study, investigating the changing sedimentological units in the study area. Analysis suggest these represent various coastal environments and were deposited during times of lower than present sea level and during the later stages of the Holocene transgression. A multi-disciplinary approach was applied by compiling existing elevation raster grids, bathymetric charts, one hundred lithological borehole data-sets, and a 110 km-long sub-bottom geophysical survey. Based on seismic stratigraphic analysis, observed geometries, and reflective appearances, six bounding surfaces and seven seismic units were identified and characterized. These seismic units have been correlated with the available borehole data to produce a chronologically constrained lithostratigraphy for the area. This approach allowed us to propose a relationship between the lithological units and sea-level change and thus enable the reconstruction of Hadera coastal evolution over the last ~ 100 ka. This reconstruction suggests that the stratigraphy is dominated by lowstand aeolian and fluvial terrestrial environments, subsequently transgressed during the Holocene. The results of this study provide a valuable framework for future national strategic shallow-water infrastructure construction and also for the possible locations of past human settlements in relation to coastal evolution through time.

  2. Late Pleistocene/Holocene wetland events recorded in southeast Tengger Desert lake sediments, NW China

    D. B. Madsen; CHEN Fahu; Ch. G. Oviatt; ZHU Yan; P. J. Brantingham; R. G. Elston; R. L. Bettinger

    2003-01-01

    The area along the eastern and southeastern margins of the Tengger Desert, NW China, which is sensitive to the summer monsoon variations, was selectedfor studying the environmental conditions surrounding the transition between Paleolithic foragers and Neolithic farmer/pastoral- ists. Short cores were obtained from four lake basins in the southwestern Tengger using a hand-driven piston coring device. Proxies from these cores were supplemented by ra- diocarbon ages obtained from lake sediment cores, shoreline features and spring mound deposits. Together these records provide evidence of millennial-scale climate change events from the Pleistocene-Holocene transition to the present. Lake/wetland events, representing periods of more intensive summer monsoon, occur in the records at ~12.7-11.6, ~10.1, ~9.3, ~8.0, ~5.4, ~1.5, and ~0.8 ka BP. They do suggest that century- to millennial-scale climatic cycles are characteristic of the Holocene in the southeastern Tengger Desert although the chronology must be considered extremely tentative.

  3. Late Pleistocene river migrations in response to thrust belt advance and sediment-flux steering - The Kura River (southern Caucasus)

    von Suchodoletz, Hans; Gärtner, Andreas; Hoth, Silvan; Umlauft, Josefine; Sukhishvili, Lasha; Faust, Dominik

    2016-08-01

    follow its tectonically driven trend toward the southwest. In contrast, during generally colder periods such as the upper late Pleistocene, sediment-flux steering caused by aggradation of the transverse rivers forced the main Kura River to migrate > 10 km against that tectonically induced trend toward the northeast. Apart from giving information about the main drivers of the late Quaternary landscape evolution in this part of the southern Caucasus region, this study also helps to understand the cause of a permanent threat of settlements and the loss of fertile agricultural land in the intensively labored Marneuli Depression of southern Georgia.

  4. Plio-Pleistocene stratigraphy and relations between marine and non-marine successions in the Middle Valley of the Tiber River (Latium, Umbria)

    Girotti, O.; Università di Roma "La Sapienza", Dipartimento di Scienze della Terra; Mancini, M.; Università di Roma "La Sapienza", Dipartimento di Scienze della Terra

    2003-01-01

    The Middle Valley of the Tiber River (MVT) corresponds to the “Paglia-Tevere Graben”, a “neoautochthonous” basin developed since the latest Early Pliocene. The basin is in part linked with the intrapenninic Tiberino and Rieti Basins to the east, and with the Roman Basin to the south. The filling is mostly made up of Plio-Pleistocene marine deposits, unconformably overlaying the meso-cenozoic substratum. Two outcropping 3rd order depositional sequences have been recognised: 1) the old...

  5. Middle to Late Pleistocene vegetation and climate change in subtropical southern East Africa

    Castañeda, Isla S.; Caley, Thibaut; Dupont, Lydie; Kim, Jung-Hyun; Malaizé, Bruno; Schouten, Stefan

    2016-09-01

    In this study we investigate Pleistocene vegetation and climate change in southern East Africa by examining plant leaf waxes in a marine sediment core that receives terrestrial runoff from the Limpopo River. The plant leaf wax records are compared to a multi-proxy sea surface temperature (SST) record and pollen assemblage data from the same site. We find that Indian Ocean SST variability, driven by high-latitude obliquity, exerted a strong control on the vegetation of southern East Africa during the past 800,000 yr. Interglacial periods were characterized by relatively wetter and warmer conditions, increased contributions of C3 vegetation, and higher SST, whereas glacial periods were marked by cooler and arid conditions, increased contributions of C4 vegetation, and lower SST. We find that Marine Isotope Stages (MIS) 5e, 11c, 15e and 7a-7c are strongly expressed in the plant leaf wax records but MIS 7e is absent while MIS 9 is rather weak. Our plant leaf wax records also record the climate transition associated with the Mid-Brunhes Event (MBE) suggesting that the pre-MBE interval (430-800 ka) was characterized by higher inputs from grasses in comparison to relatively higher inputs from trees in the post-MBE interval (430 to 0 ka). Differences in vegetation and SST of southern East Africa between the pre- and post-MBE intervals appear to be related to shifts in the location of the Subtropical Front. Comparison with vegetation records from tropical East Africa indicates that the vegetation of southern East Africa, while exhibiting glacial-interglacial variability and notable differences between the pre- and post-MBE portions of the record, likely did not experience such dramatic extremes as occurred to the north at Lake Malawi.

  6. Tracing subarctic Pacific water masses with benthic foraminiferal stable isotopes during the LGM and late Pleistocene

    Cook, Mea S.; Ravelo, A. Christina; Mix, Alan; Nesbitt, Ian M.; Miller, Nari V.

    2016-03-01

    As the largest ocean basin, the Pacific helps to set the global climate state, since its circulation affects mean ocean properties, air-sea partitioning of carbon dioxide, and the distribution of global oceanic poleward heat transport. There is evidence that during the Last Glacial Maximum (LGM) the subarctic Pacific contained a better-ventilated, relatively fresh intermediate water mass above ~2000 m that may have formed locally. The source and spatial extent of this water mass is not known, nor do we know how formation of this water mass varied during Pleistocene glaciations with different orbital and ice sheet boundary conditions. Here we present a 0.5 My multi-species benthic stable isotope record from Site U1345 (1008 m) on the northern Bering slope and a 1.0 My record from U1339 (1868 m) from the Umnak Plateau in the southeastern basin. We find that the relatively well-ventilated low-δ18O intermediate water reaches 1000 m in the Bering Sea during MIS2, but that the hydrographic divide between this water mass and poorly-ventilated deep water was shallower than 1000 m for earlier glaciations. We also compare Bering Sea piston core and IODP Expedition 323 Uvigerina data from the Holocene and LGM with the modern hydrography, and to previously published profiles from the Okhotsk Sea and Emperor Seamounts. We find that the carbon and oxygen stable isotope signatures of well-ventilated water in the Bering and Okhotsk Seas are distinct, suggesting that there may have been intermediate water formation in both basins during the LGM.

  7. Palynological evidence for vegetation patterns in the Transvaal (South Africa during the late Pleistocene and Holocene

    L. Scott

    1983-12-01

    Full Text Available Palynological evidence relating to the nature of Late Quaternary vegetation types and plant migrations in the Transvaal is briefly summarized. It is suggested that, after an early temperate, relatively moist phase and a subsequent relatively dry phase lasting until about 25 000 yr B.P., a vegetation-type with ericaceous elements developed. It resembled belts presently occurring above the treeline and was possibly widespread over the plains of the Transvaal during the last glacial maximum period. In the central parts of the province, warm semi-arid savanna subsequently expanded during the early Holocene and was followed by a more broad-leafed type of woodland in the late Holocene. This change probably resulted from slightly wetter and, at times, also slightly warmer and cooler conditions.

  8. Late pleistocene glacial and environmental history of the Skagit valley, Washington and British Columbia

    Riedel, Jon Lyle

    2007-01-01

    Drainage patterns established in the Tertiary in the North Cascades were reorganized to accommodate southern drainage of Cordilleran Ice Sheet meltwater. Repeated continental glaciation rendered the Skagit an interconnected valley, with meltwater routes opening it to the Fraser and Okanogan watersheds, and linking it to a drainage system around the east margin of the Puget lobe of the ice sheet. Alpine glaciers from two major tributaries blocked Skagit valley during the late Wisconsin Evans C...

  9. Landscape response to late Pleistocene climate change in NW Argentina: Sediment flux modulated by basin geometry and connectivity

    Schildgen, Taylor F.; Robinson, Ruth A. J.; Savi, Sara; Phillips, William M.; Spencer, Joel Q. G.; Bookhagen, Bodo; Scherler, Dirk; Tofelde, Stefanie; Alonso, Ricardo N.; Kubik, Peter W.; Binnie, Steven A.; Strecker, Manfred R.

    2016-02-01

    Fluvial fill terraces preserve sedimentary archives of landscape responses to climate change, typically over millennial timescales. In the Humahuaca Basin of NW Argentina (Eastern Cordillera, southern Central Andes), our 29 new optically stimulated luminescence ages of late Pleistocene fill terrace sediments demonstrate that the timing of past river aggradation occurred over different intervals on the western and eastern sides of the valley, despite their similar bedrock lithology, mean slopes, and precipitation. In the west, aggradation coincided with periods of increasing precipitation, while in the east, aggradation coincided with decreasing precipitation or more variable conditions. Erosion rates and grain size dependencies in our cosmogenic 10Be analyses of modern and fill terrace sediments reveal an increased importance of landsliding compared to today on the west side during aggradation, but of similar importance during aggradation on the east side. Differences in the timing of aggradation and the 10Be data likely result from differences in valley geometry, which causes sediment to be temporarily stored in perched basins on the east side. It appears as if periods of increasing precipitation triggered landslides throughout the region, which induced aggradation in the west, but blockage of the narrow bedrock gorges downstream from the perched basins in the east. As such, basin geometry and fluvial connectivity appear to strongly influence the timing of sediment movement through the system. For larger basins that integrate subbasins with differing geometries or degrees of connectivity (like Humahuaca), sedimentary responses to climate forcing are likely attenuated.

  10. Conceptual hydrochemical model of late Pleistocene aquifers at the Samario-Sitio Grande petroleum reservoir, Gulf of Mexico

    Birkle, P. [Instituto de Investigaciones Electricas, Gerencia de Geotermia, Cuernavaca, Mor. (Mexico); Angulo, M. [PEMEX-Exploracion y Produccion, Chiapas (Mexico)

    2005-06-01

    Carbon-14 concentrations between 0.83 and 11.79 pmC of formation water from the Activo Samaria-Sitio Grande petroleum reservoir in SE-Mexico, extracted from 3500 to 4500 m.b.s.l., indicate a common infiltration event of surface water during the late Pleistocene period. Mixing of two components - meteoric water and seawater, previously evaporated at the surface - explain the widespread mineralization (TDI = 15-257 g/L) of Na-Cl and Na-Ca-Cl type reservoir water. Statistical discrimination by clustering and a heterogeneous chemical-isotopic fluid composition indicate the existence of 4 different water types as part of local aquifer systems, which are separated by normal and thrust faults. Tectonic horst and graben structures show an ambiguous, individual hydraulic behaviour - as permeable conduits and/or as impermeable barriers, causing the local limitation of aquifer extent. The recent increase of water production in petroleum wells is not related to the injection of surface water, but the long-term extraction of oil reserves is modifying the original position and flow direction of the reservoir aquifers. The rise of the initial groundwater level reflects the final stage of an exhausted petroleum reservoir with coning effects of underlying aquifer systems. The flexible change towards superior production intervals could represent a feasible technique to avoid the abrupt closure of invaded production wells. (Author)

  11. Conceptual hydrochemical model of late Pleistocene aquifers at the Samario-Sitio Grande petroleum reservoir, Gulf of Mexico, Mexico

    Birkle, Peter [Instituto de Investigaciones Electricas, Gerencia de Geotermia, Av. Reforma 113, Col. Palmira, Cuernavaca, Mor., 62490 (Mexico)]. E-mail: birkle@iie.org.mx; Angulo, Maricela [PEMEX - Exploracion y Produccion, Diseno de Explotacion Cactus-Nispero Sitio Grande, Zona Industrial S/N, Reforma, Chiapas (Mexico)

    2005-06-15

    Carbon-14 concentrations between 0.83 and 11.79 pmC of formation water from the Activo Samaria-Sitio Grande petroleum reservoir in SE-Mexico, extracted from 3500 to 4500 m.b.s.l., indicate a common infiltration event of surface water during the late Pleistocene period. Mixing of two components - meteoric water and seawater, previously evaporated at the surface - explain the widespread mineralization (TDI = 15-257 g/L) of Na-Cl and Na-Ca-Cl type reservoir water. Statistical discrimination by clustering and a heterogeneous chemical-isotopic fluid composition indicate the existence of 4 different water types as part of local aquifer systems, which are separated by normal and thrust faults. Tectonic horst and graben structures show an ambiguous, individual hydraulic behaviour - as permeable conduits and/or as impermeable barriers, causing the local limitation of aquifer extent. The recent increase of water production in petroleum wells is not related to the injection of surface water, but the long-term extraction of oil reserves is modifying the original position and flow direction of the reservoir aquifers. The rise of the initial groundwater level reflects the final stage of an exhausted petroleum reservoir with coning effects of underlying aquifer systems. The flexible change towards superior production intervals could represent a feasible technique to avoid the abrupt closure of invaded production wells.

  12. Estimation of the shortening rate since late Pleistocene in the Aksu area on the southern flank of the Tianshan, China

    2001-01-01

    This research focused on the Aksu area in the central part of the southern Tianshan. Along the 60 km wide Aksu fold-and-thrust belt, active thrusts reach the surface and offset the youngest sediments. Our research was based on the geomorphologic study that examined the advance and retreat of glaciers cut by thrusts in the Tomur area in the north of Aksu. Our fieldwork revealed that two fault scarps were clearest across three different moraines that represent the maximum of advance of glaciers during three glacial periods along the Tailan River in the Tomur area. The measured heights of the fault scarps that cut the moraines, together with the moraines-inferred age, imply a shortening rate of 1.85 mm/a on the Aksu area since late Pleistocene. This rate, similar to that of the Korla area on its east side and of the Kaping area on its west side, but lower than that of the Kashgar area farther west and of the Manas area in the northern margin of the belt, implies that the distribution of shortening across the Tianshan changed markedly along the mountain.

  13. Conceptual hydrochemical model of late Pleistocene aquifers at the Samario-Sitio Grande petroleum reservoir, Gulf of Mexico, Mexico

    Carbon-14 concentrations between 0.83 and 11.79 pmC of formation water from the Activo Samaria-Sitio Grande petroleum reservoir in SE-Mexico, extracted from 3500 to 4500 m.b.s.l., indicate a common infiltration event of surface water during the late Pleistocene period. Mixing of two components - meteoric water and seawater, previously evaporated at the surface - explain the widespread mineralization (TDI = 15-257 g/L) of Na-Cl and Na-Ca-Cl type reservoir water. Statistical discrimination by clustering and a heterogeneous chemical-isotopic fluid composition indicate the existence of 4 different water types as part of local aquifer systems, which are separated by normal and thrust faults. Tectonic horst and graben structures show an ambiguous, individual hydraulic behaviour - as permeable conduits and/or as impermeable barriers, causing the local limitation of aquifer extent. The recent increase of water production in petroleum wells is not related to the injection of surface water, but the long-term extraction of oil reserves is modifying the original position and flow direction of the reservoir aquifers. The rise of the initial groundwater level reflects the final stage of an exhausted petroleum reservoir with coning effects of underlying aquifer systems. The flexible change towards superior production intervals could represent a feasible technique to avoid the abrupt closure of invaded production wells

  14. The late Pleistocene horned crocodile Voay robustus (Grandidier & Vaillant, 1872) from Madagascar in the Museum für Naturkunde Berlin

    C. Bickelmann; Klein, N

    2009-01-01

    Crocodylian material from late Pleistocene localities around Antsirabe, Madagascar, stored in the collection of the Museum für Naturkunde, Berlin, was surveyed. Several skeletal elements, including skull bones, vertebrae, ribs, osteoderms, and limb bones from at least three large individuals could be unambiguously assigned to the genus Voay Brochu, 2007. Furthermore, the simultaneous occurrence of Voay robustus Grandidier & Vaillant, 1872 and Crocodylus niloticus Laurenti, 1768 in Madagascar ...

  15. The late Pleistocene horned crocodile Voay robustus (Grandidier & Vaillant, 1872) from Madagascar in the Museum für Naturkunde Berlin

    C. Bickelmann; Klein, N

    2009-01-01

    Crocodylian material from late Pleistocene localities around Antsirabe, Madagascar, stored in the collection of the Museum für Naturkunde, Berlin, was surveyed. Several skeletal elements, including skull bones, vertebrae, ribs, osteoderms, and limb bones from at least three large individuals could be unambiguously assigned to the genus Voay Brochu, 2007. Furthermore, the simultaneous occurrence of Voay robustus Grandidier & Vaillant, 1872 and Crocodylus niloticus Laurenti, 1768 in Madagascar ...

  16. Applied Stratigraphy

    Lucas, Spencer G.

    Stratigraphy is a cornerstone of the Earth sciences. The study of layered rocks, especially their age determination and correlation, which are integral parts of stratigraphy, are key to fields as diverse as geoarchaeology and tectonics. In the Anglophile history of geology, in the early 1800s, the untutored English surveyor William Smith was the first practical stratigrapher, constructing a geological map of England based on his own applied stratigraphy. Smith has, thus, been seen as the first “industrial stratigrapher,” and practical applications of stratigraphy have since been essential to most of the extractive industries from mining to petroleum. Indeed, gasoline is in your automobile because of a tremendous use of applied stratigraphy in oil exploration, especially during the latter half of the twentieth century. Applied stratigraphy, thus, is a subject of broad interest to Earth scientists.

  17. A Brief Overview of the Last 10 Years of Major Late Pleistocene Discoveries in the Old World: Homo floresiensis, Neanderthal, and Denisovan

    Fernanda Neubauer

    2014-01-01

    Full Text Available In the last ten years, new fossil, archaeological, and genetic data have significantly altered our understanding of the peopling of the Old World in the Late Pleistocene. Scholars have long been challenged to define humanity’s place in evolution and to trace our phylogeny. Differences in the skeletal morphology of hominin fossils have often led to the naming of distinct new species, but recent genetic findings have challenged the traditional perspective by demonstrating that modern human DNA contains genes inherited from Neanderthals and Denisovans, thus questioning their status as separate species. The recent discovery of Homo floresiensis from Flores Island has also raised interesting queries about how much genetic and morphological diversity was present during the Late Pleistocene. This paper discusses the nature and implications of the evidence with respect to Homo floresiensis, Neanderthals, and Denisovans and briefly reviews major Late Pleistocene discoveries from the last ten years of research in the Old World and their significance to the study of human evolution.

  18. Evidence for prolonged El Nino-like conditions in the Pacific during the Late Pleistocene: a 43 ka noble gas record from California groundwaters

    Kulongoski, J.T.; Hilton, David R.; Izbicki, J.A.; Belitz, K.

    2009-01-01

    Information on the ocean/atmosphere state over the period spanning the Last Glacial Maximum - from the Late Pleistocene to the Holocene - provides crucial constraints on the relationship between orbital forcing and global climate change. The Pacific Ocean is particularly important in this respect because of its dominant role in exporting heat and moisture from the tropics to higher latitudes. Through targeting groundwaters in the Mojave Desert, California, we show that noble gas derived temperatures in California averaged 4.2 ?? 1.1 ??C cooler in the Late Pleistocene (from ???43 to ???12 ka) compared to the Holocene (from ???10 to ???5 ka). Furthermore, the older groundwaters contain higher concentrations of excess air (entrained air bubbles) and have elevated oxygen-18/oxygen-16 ratios (??18O) - indicators of vigorous aquifer recharge, and greater rainfall amounts and/or more intense precipitation events, respectively. Together, these paleoclimate indicators reveal that cooler and wetter conditions prevailed in the Mojave Desert from ???43 to ???12 ka. We suggest that during the Late Pleistocene, the Pacific ocean/atmosphere state was similar to present-day El Nino-like patterns, and was characterized by prolonged periods of weak trade winds, weak upwelling along the eastern Pacific margin, and increased precipitation in the southwestern U.S.

  19. Constraining the Late Pleistocene history of the Laurentide Ice Sheet by dating the Missinaibi Formation, Hudson Bay Lowlands, Canada

    Dalton, April S.; Finkelstein, Sarah A.; Barnett, Peter J.; Forman, Steven L.

    2016-08-01

    Well-dated paleorecords from periods prior to the Last Glacial Maximum (LGM) are important for validating models of ice sheet build-up and growth. However, owing to glacial erosion, most Late Pleistocene records lie outside of the previously glaciated region, which limits their ability to inform about the dynamics of paleo-ice sheets. Here, we evaluate new and previously published chronology data from the Missinaibi Formation, a Pleistocene-aged deposit in the Hudson Bay Lowlands (HBL), Canada, located near the geographic center of the Laurentide Ice Sheet (LIS). Available radiocarbon (AMS = 44, conventional = 36), amino acid (n = 13), uranium-thorium (U-Th, n = 14), thermoluminescence (TL, n = 15) and optically stimulated luminescence (OSL, n = 5) data suggest that an ice-free HBL may have been possible during parts of Marine Isotope Stage 7 (MIS 7; ca. 243,000 to ca. 190,000 yr BP), MIS 5 (ca. 130,000 to ca. 71,000 yr BP) and MIS 3 (ca. 29,000 to ca. 57,000). While MIS 7 and MIS 5 are well-documented interglacial periods, the development of peat, forest bed and fluvial deposits dating to MIS 3 (n = 20 radiocarbon dates; 4 TL dates, 3 OSL dates), suggests that the LIS retreated and remained beyond, or somewhere within, the boundaries of the HBL during this interstadial. Ice sheet models approximate the margin of the LIS to Southern Ontario during this time, which is 700 km south of the HBL. Therefore, if correct, our data help constrain a significantly different configuration and dynamicity for the LIS than previously modelled. We can find no chronological basis to discount the MIS 3 age assignments. However, since most data originate from radiocarbon dates lying close to the reliable limit of this geochronometer, future work on dating the Missinaibi Formation using other geochronological methods (e.g. U-Th, OSL) is necessary in order to confirm the age estimates and strengthen the boundaries of the LIS during this period.

  20. Late Pliocene - Early Pleistocene paleoenvironmental reconstruction based on stable isotope compositions of Stephanorhinus sp. and Mammut sp. teeth

    Szabó, Péter; Kovács, János; Kocsis, László; Gasparik, Mihály; Vennemann, Torsten; Demény, Attila; Virág, Attila

    2014-05-01

    Stable isotope measurements of skeletal apatite from herbivorous mammals are often used to provide information on the terrestrial paleoenvironment and paleoclimate. In this study fossil teeth of Stephanorhinus Kretzoi 1942 (rhinoceros) and Mammut Blumenbach 1799 (mastodon), amongst others, were investigated from the Carpathian Basin. According to the biostratigraphy, the age of the samples has a range from Late Pliocene to Early Pleistocene. Reconstructing paleoclimate and paleoenvironment of this era is important as it can be an analogue for the future climate. Oxygen and carbon isotopic compositions were measured from the tooth enamel, because it is believed to be the most resistant to diagenetic alteration (e.g., Kohn & Cerling, 2002). The carbon isotopic composition in the carbonate fraction of apatite can be related to the diet of the animal (Kohn & Cerling, 2002). Hence, it can reflect the photosynthetic pathway (C3 or C4) of the plants consumed by these herbivores. The δ18O values were determined in the phosphate fraction of apatite. In the case of large mammals that are obligate drinkers, the δ18O values closely track those of the environmental water (Bryant & Froelich, 1995). Knowing the δ18O values of environmental water and relating it to local precipitation, the mean annual temperature (MAT) of the site can be calculated (Dansgaard, 1964). The δ13C values range from -10 to -15 o (VPDB). The result clearly shows that these animals consumed C3 plants. Most of the δ13C values indicate mixed grassland-open woodland rather than a closed canopy forest. Although there is variation in the δ18O values (mean 14.2 ± 1.0 o VSMOW, n=17), most of the samples would support a MAT range of 8-12 ° C. This is in good agreement with other proxies for the localities and time period (Kovács et al., 2013). Bryant, D.J. & Froelich, P.N. (1995) A model of oxygen-isotope fractionation in bodywater of large-mammals. Geochimica et Cosmochimica Acta 59, 4523

  1. Evidence for early Pleistocene Glaciation(s) in tropical Africa: Stratigraphy, Paleomagnetism, Paleosols and Paleoclimate of the Gorges Moraine System, Mount Kenya

    Mahaney, W. C.; Barendregt, R. W.; Hamilton, T.; Hancock, R.

    2011-12-01

    Moraines marking an Early Pleistocene glaciation on Mt. Kenya are known from several valleys marking the lowermost extent of the Early Pleistocene Gorges Glaciation (2850 m a.s.l.). The lowermost paleosols at these sites formed either in till predating the Gorges Glaciation or in weathered phonolitic bedrock and related lavas, similar to the lithology forming the base of the Mt. Kenya volcanic series of Miocene/Pliocene age. Paleomagnetism and weathering characteristics have been used to refine the age of sediments assigned to the Gorges Glaciation. These deposits are normally magnetized but carry a persistent reversed overprint, suggesting that they were deposited during one of the normal subchrons within the Matuyama Reversed Chron. They are underlain either by a reversely magnetized weathered till (GOR 68), or weathered bedrock (GOR 64 and GOR 69), the latter exhibiting normal magnetization (Gauss?) with reversed overprint (Matuyama?). The sediments are overlain at all three sites by normally magnetized loesses and paleosols of presumable Brunhes age. The normal magnetization and reversed overprint recorded in sediments of the Gorges Glaciation most likely span a considerable portion of the Olduvai subchron (1.78-1.950 Ma.), which persisted for sufficient time to accommodate an extensive montane glaciation and prolonged period of weathering and soil formation. While the somewhat younger Jaramillo subchron cannot be ruled out, the extensive sediment and weathering record is more easily accommodated within the longer-lived Olduvai subchron. The characteristics of the lowermost buried paleosols and weathered bedrock substrate indicate wetter conditions prior to the onset of Pleistocene glaciation, a period that initially may have fostered a higher elevation forest cover of substantial spatial extent. These wetter conditions, punctuated with dry events, depict a progressive transition to alpine grassland at the start of the Quaternary. In light of new paleomagnetic

  2. Spring deposits and late pleistocene ground-wter levels in southern Nevada

    Ground-water discharge deposits dating to the last glacial cycle and to several earlier cycles crop out in at least ten valleys in the southern Great Basin. The elevation and distribution of these deposits allow us to reconstruct the elevation of the water table during periods of wetter climate over much of the region, including the area around Yucca Mountain, site of the proposed high-level nuclear waste repository. Results from areas undisturbed by recent ground-water pumpage reveal that water levels have varied by < 115 m, and in most cases much less, in the latter half of the Quaternary. The extent of ground-water discharge during older wet cycles is similar in scale to discharge during the last full-glacial period. This places most of the proposed repository horizon at least 85 to 285 m above the maximum levels attained by the water table under full-glacial climates. During the late-glacial period (∼11,500 to 8000 B.P.), a pulse of renewed discharge, perhaps corresponding to the Younger Dryas event well-documented elsewhere, produced organic-rich mats and flowing streams in many localities

  3. Age, palaeoenvironments, and climatic significance of late Pleistocene Konya lake, Turkey

    Roberts, Neil

    1983-03-01

    The Konya Basin, a closed depression at the southern margin of the Anatolian Plateau, contained a shallow but extensive lake during the late Quaternary. Nearshore sands and gravels containing Dreissena shells form prominent depositional terraces around the basin edges at elevations between 1005 and 1020 m, and the highest has been dated at more than 30,000 yr B.P. The last major phase of limnic sedimentation occurred between 23,000 and 17,000 yr B.P., after which the lake fragmented into a number of subbasins or secondary depressions which evolved to become either marshes or playas. A final expansion of these residual lakes has been dated to ca. 11,000 yr B.P. in one secondary depression. Archaeological and other evidence indicate that only minor lake-level fluctuations occurred during the Holocene. The dominant sedimentary process over the last 10,000 years has been alluviation at the basin margin. The Konya sequence confirms that the most recent period of high-lake levels in the northern Near East was of the last glacial age. The palaeolakes of Anatolia and Iran were, however, more a product of reduced evaporation brought about by temperature depression than of changes in precipitation, and thus belie their often-used description as an indicator of "pluvial" climatic conditions.

  4. Stratigraphy, Sequence, and Crater Populations of Lunar Impact Basins from Lunar Orbiter Laser Altimeter (LOLA) Data: Implications for the Late Heavy Bombardment

    Fassett, C. I.; Head, J. W.; Kadish, S. J.; Mazarico, E.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.

    2012-01-01

    New measurements of the topography of the Moon from the Lunar Orbiter Laser Altimeter (LOLA)[1] provide an excellent base-map for analyzing the large crater population (D.20 km)of the lunar surface [2, 3]. We have recently used this data to calculate crater size-frequency distributions (CSFD) for 30 lunar impact basins, which have implications for their stratigraphy and sequence. These data provide an avenue for assessing the timing of the transitions between distinct crater populations characteristic of ancient and young lunar terrains, which has been linked to the late heavy bombardment (LHB). We also use LOLA data to re-examine relative stratigraphic relationships between key lunar basins.

  5. Variable scale channel avulsion history using fan architecture and stratigraphy, and sediment provenance of Sutlej-Yamuna fans in northwest Gangetic plains during Late Quaternary

    Singh, Ajit; Gupta, Sanjeev; Sinha, Rajiv; Densmore, Alexander; Buylaert, Jan-Pieter; Carter, Andrew; Van-Dijk, Wout M.; Joshi, Suneel; Nayak, Nibedita; Mason, Philippa J.; Kumar, Dewashish; Mondal, Setbandhu; Murray, Andrew; Rai, Shiv P.; Shekhar, Shashank

    2016-04-01

    Channel avulsion during fan development controls distribution and deposition of channel sandbodies and hence alluvial architecture of a fan system. Variable scale spatio-temporal information of fluvial responses to past climate changes is stored in these channel sandbodies. Further these channel sandbodies form fluvial aquifers in alluvial fans and therefore understanding of alluvial architecture and stratigraphy of a fan is crucial for development of groundwater management strategies. In this study we used multiple approaches to map subsurface fluvial aquifer architecture and alluvial stratigraphy, and to estimate sediment provenance using U-Pb dating of detrital zircon grains of Sutlej-Yamuna fan system in northwest India. Satellite imagery based geomorphic mapping shows two large fan system with interfan area. The fan surfaces show presence of major and minor paleochannels. 2D resistivity tomography along several transects across fan surfaces shows distinct layers with contrasting resistivity values. These geo-electric facies corresponds to presence of channel sandbodies beneath surface signature of paleochannels and finer floodplain deposits useful to demarcate lateral extent of subsurface channel sandbodies. A more detailed subsurface stratigraphy using ~50m deep sediment cores and their luminescence ages from across fan surface shows presence of multi-storey sandbodies (MSB) separated by floodplain fines. Within the MSB, individual channel deposits are identified by presence of channel scour surfaces located at coarse sand overlying fine sand layer. Depositional ages of MSB's ranges from ~81 ka (late MIS5) to ~15 ka (MIS2) with major depositional break during MIS3 in parts of the fans. Sediment aggradation rate varies laterally across fan surface as well as vertically down the depth with an average rate of 0.54 mm/year. Fluvial channel persistence for studied time interval (about last 81 ka BP) shows major depositional breaks (and possible incision) at ~41 ka

  6. Tapping the Late Pleistocene-Holocene environmental change and alluvial geoarchaeology in Central Asia

    Macklin, Mark; Panyushkina, Irina; Toonen, Willem; Chang, Claudia; Seitkaliyev, Meyram; Voyakin, Dmitry

    2015-04-01

    We integrate the environmental history derived from spatial-temporal variability of multi proxies and the prehistory of arid lands from archaeological data in Central Asia in order to determine the relationship between the Holocene river dynamics, climate change and floodwater farming. This study addresses to developing fluvial achieves and geoarcheological records from the Talgar catchment, a south-bank tributary of the Ili River and the Talas catchment, a east-bank tributary of the Syr Darya River, in the southern Kazakhstan. The catchments of these steppe rivers flowing northwest had favorable habitats for farming from the Eneolithic to the medieval period as appears from human settlement histories documented with archaeological surveys and in some cases excavations. The river development has been reconstructed over the last 20,000 years and the key archaeological sites have been dated with radiocarbon. Periods of Holocene river aggradation and high water in downstream Lake Balkhash and Aral Sea correspond with cooler and wetter neoglacial episodes while river entrenchment and floodplain soil development are associated with warmer and drier conditions. Floodwater farming in the Talgar River reached its height in the late Iron Age (400-200 cal. BC) with more than 70 settlement sites and 700 burial mounds, and in the Talas River during the medieval period. This corresponds to a period of reduced flood flows, river stability and glacier retreat in the Tien Shan headwaters. A new hydroclimatic-based model for the spatial and temporal dynamics of floodwater farming is proposed, which explains settlement patterns since the first documented use of irrigation in the Iron Age and medieval times. The undertaken research highlights the Holocene human adaptations to the environmental change of floodplains in Central Asia.

  7. Late Pleistocene and Holocene large magnitude earthquakes along Himalayan Frontal Thrust in the Central Seismic Gap in NW Himalaya, Kala Amb, India

    Philip, G.; Bhakuni, S. S.; Suresh, N.

    2012-12-01

    The Himalayan Frontal Thrust (HFT) forms the southernmost active tectonic mountain front of the Himalaya. To understand the ongoing tectonics further, paleoseismological study has been carried out in the vicinity of the HFT system along the Himalayan Front near Kala Amb, India. The trench excavation survey conducted across an explicit surface exposure of the HFT exhibits two distinct faults considered to be associated with the reactivation of the HFT where the Middle Siwalik rocks (Late Miocene) have repeatedly thrust over the Late Pleistocene and Holocene sediments. Presence of large-sized coseismically induced sand-injection feature and its disposition recognized in the trench also suggest occurrence of large magnitude earthquakes in this region. An uplifted and upwarped strath terrace, 3 to 5 m thick alluvium, resting over the 15 m high Middle Siwaliks, abruptly truncated by the HFT indicates its latest activity. Optically Stimulated Luminescence dating techniques were employed to constrain the chronology of events. The long term slip rate of the abandoned terraces due to the activity of the HFT is estimated to be 3.4 mm/yr or greater since Late Holocene. The paleoseismological investigations have provided unambiguous evidences of at least two large magnitude earthquakes occurred in this region where an earthquake with 12 m or larger surface displacement and magnitude 7.5 or greater hit this region in the period between 29.3 ka and 17 ka in the Late Pleistocene and another great earthquake recurred with 20-22 m or more surface displacement and magnitude of 7.7 or greater between 5.8 ka and 2 ka in the Holocene. The present study is the first time report of multiple large magnitude paleoearthquakes in the northwestern part of the Frontal Himalaya during Late Pleistocene and Holocene. The repeated reactivation of HFT substantiates high seismic potential of the Frontal Himalaya and calls for more extensive study of paleoearthquakes of this vastly populous

  8. Glacial chronology and palaeoclimate in the Bystra catchment, Western Tatra Mountains (Poland) during the Late Pleistocene

    Makos, Michał; Rinterknecht, Vincent; Braucher, Régis; Żarnowski, Michał

    2016-02-01

    Deglaciation chronology of the Bystra catchment (Western Tatra Mountains) has been reconstructed based on 10Be exposure age dating. Fourteen rock samples were collected from boulders located on three moraines that limit the horizontal extent of the LGM maximum advance and the Lateglacial recessional stage. The oldest preserved, maximum moraine was dated at 15.5 ± 0.8 ka, an age that could be explained more likely by post-depositional erosion of the moraine. Such scenario is supported by geomorphologic and palaeoclimatological evidence. The younger cold stage is represented by well-preserved termino-lateral moraine systems in the Kondratowa and Sucha Kasprowa valleys. The distribution of the moraine ridges in both valleys suggest a complex history of deglaciation of the area. The first Late-glacial re-advance (LG1) was followed by a cold oscillation (LG2), that occurred at around 14.0 ± 0.7-13.7 ± 1.2 ka. Glaciers during both stages had nearly the same horizontal extent, however, their thickness and geometry changed significantly, mainly due to local climatic conditions triggered by topography, controlling the exposition to solar radiation. The LG1 stage occurred probably during the pre-Bølling cold stage (Greenland Stadial 2.1a), however, the LG2 stage can be correlated with the cooling at around 14 ka during the Greenland Interstadial 1 (GI-1d - Older Dryas). This is the first chronological evidence of the Older Dryas in the Tatra Mountains. The ELA of the maximum Bystra glacier was located at 1480 m a.s.l. in accordance with the ELA in the High Tatra Mountains during the LGM. During the LG1 and LG2 stages, the ELA in the catchment rose up to 1520-1530 m a.s.l. and was located approximately 100-150 m lower than in the eastern part of the massif. Climate modelling results show that the Bystra glacier (maximum advance) could have advanced in the catchment when mean annual temperature was lower than today by 11-12 °C and precipitation was reduced by 40-60%. This

  9. Multiproxy evidence of Late Pleistocene environmental changes in the loess-paleosol sequence of Bůhzdař (Czech Republic)

    Flašarová, Kristýna; Vysloužilová, Barbora; Juřičková, Lucie; Šefrna, Luděk; Verecchia, Eric

    2016-04-01

    Europe. Eiszeitalter und Gegenwart, Quaternary Science Journal, 60 (1) http://doi.org/10.3285/eg.60.1.00 Kaakinen, A., Sonninen, E., & Lunkka, J. P. (2006). Stable isotope record in paleosol carbonates from the Chinese Loess Plateau: Implications for late Neogene paleoclimate and paleovegetation. Palaeogeography, Palaeoclimatology, Palaeoecology, 237 (2-4), 359-369. http://doi.org/10.1016/j.palaeo.2005.12.011 Ložek, V. (1952) Zpráva o paleontologickém výzkumu cihelny v Zájezdu u Buštěhradu. Anthropozoikum, III, 135-138. Obreht, I., Buggle, B., Catto, N., Markovič, S. B., Bösel, S., Vandenberghe, D. A. G., … Jović, G. (2014). The Late Pleistocene Belotinac section (southern Serbia) at the southern limit of the European loess belt: Environmental and climate reconstruction using grain size and stable C and N isotopes. Quaternary International, 334-335, 10-19. http://doi.org/10.1016/j.quaint.2013.05.037

  10. Millennial-scale varnish microlamination dating of late Pleistocene geomorphic features in the drylands of western USA

    Liu, Tanzhuo; Broecker, Wallace S.

    2013-04-01

    Varnish microlamination (VML) dating is a climate-based correlative age determination technique used to correlate and date various geomorphic features in deserts. In this study, we establish a generalized late Pleistocene (18-74 ka) millennial-scale microlamination sequence in fine-grained, fast-accumulating rock varnish for the drylands of western USA, radiometrically calibrate the sequence and correlate it with the δ18O record in the GISP2 Greenland ice core. We then use this climate-correlated varnish microstratigraphy to estimate surface exposure ages for radiometrically dated late Pleistocene geomorphic features in the study region. The VML dating of debris flow deposits on the Sehoo recessional shorelines of Lake Lahontan at the Jessup embayment of central Nevada yields a minimum-limiting age of 14.95-15.95 ka, in good agreement with a calibrated 14C age of 15.22 ± 0.12 ka for the timing of the lake recession. The VML dating of a giant ejecta block on the rim of Meteor Crater in northern Arizona yields a minimum-limiting age of 49.15 ka, closely matching a thermoluminescence (TL) age of 49 ± 3 ka and slightly younger than a recently updated cosmogenic 36Cl age of 56.0 ± 2.4 ka for the meteor impact event. The VML dating of distal Q2c fan surfaces on Hanaupah Canyon alluvial fan in Death Valley, California, yields a minimum-limiting age of 73.55 ka, in accord with cosmogenic 36Cl depth-profile ages of 66 + 22/-14 ka and 72 + 24/- 20 ka for the same fan deposits. The close agreement between the VML age estimates and the independently derived radiometric ages for these geomorphic features attests to the validity and reliability of millennial-scale VML dating. To further assess its potential in desert geomorphological research, we use the VML method to study alluvial-fan responses to millennial-scale climatic changes. The VML dating of a small tributary fan in Death Valley reveals two episodes of fan aggradation, one ceasing at 73.55-86.75 ka during the dry

  11. The genesis of solution pipes: Evidence from the Middle-Late Pleistocene Bridgewater Formation calcarenite, southeastern Australia

    Lipar, Matej; Webb, John A.; White, Susan Q.; Grimes, Ken G.

    2015-10-01

    Solution pipes are abundant in Late Pleistocene aeolian calcarenites at Cape Bridgewater in southwestern Victoria, and were studied using field work, morphometric analysis, thin sections, mineralogical and chemical analyses, and OSL dating. The solution pipes are vertical tubes formed in aeolian limestone with matrix porosity. They are typically 0.1-1 m wide and 1-5 m deep, with rounded terminations and cemented rims up to 10 cm thick. They are overlain by palaeosols and filled mostly with palaeosol material; rhizoliths are commonly present in the solution pipe fills and the surrounding calcarenite. The solution pipes have formed by focused dissolution of aeolianite, relatively quickly after the sand deposition, and concurrently filled with soil as they developed. They most likely formed beneath trees (as a result of focused infiltration due to stemflow) or due to fingered flow (unstable wetting front that breaks into fingers as it moves downwards). Solution pipe formation was strongly dependent on climate; periods of solution pipe formation followed the deposition of aeolianites at the end of interglacials MIS 7, 9 and 11, when the dunes were stabilised by vegetation and there was sufficient rainfall for substantial subsoil dissolution. The cemented rims formed in the following drier glacial climates. Solution pipes are most abundant in the youngest aeolianite, probably reflecting the wetter climate at the end of MIS 7 that allowed a dense forest to cover the dunes. From MIS 5 to MIS 2 no deposition of calcareous sand occurred on Cape Bridgewater, and combined with a very wet interglacial period MIS 5e, resulted in additional karstification, allowing the pipes in the MIS 7 aeolianite to extend deeper and drill down into the underlying member. A well-developed calcrete layer drapes over these solution pipes, and probably formed during the dry, windy climate of the Last Glacial Maximum.

  12. Stable carbon isotope reconstructions of diet and paleoenvironment from the late Middle Pleistocene Snake Cave in Northeastern Thailand

    Pushkina, Diana; Bocherens, Herve; Chaimanee, Yaowalak; Jaeger, Jean-Jacques

    2010-03-01

    Thailand’s geographical location in the tropics and almost complete, relatively uninterrupted forest cover makes it valuable for paleodiet and paleoclimate research. We present the first dietary and environmental reconstructions in Northeastern Thailand, using stable isotope abundances in mammalian tooth enamel from the late Middle Pleistocene locality, Tham Wiman Nakin (Snake Cave), which reflect a much higher (over 70%) than modern (13%) occurrence of C4 plants. Bovids and cervids appear to have had almost entirely a C4 plant diet. Carnivores consumed a mixture of C3 (suids) and C4 (bovids, cervids) consumers. Rhinoceroses and orangutan appear to have maintained their preference through time for forested or open C3 environment, respectively. 13C/12C from bone bioapatite, horn and hair of modern Southeast Asian mammals almost exclusively demonstrate C3 vegetation dominance. C4 consumption is rare in analysed modern species and it could be related to anthropogenic influences such as ingestion of domestic crops or livestock. Interesting implications emerge in the C4 vegetation distribution in southern Eurasian ecosystems, indicating that Southeast Asia, south of the Tibet, could be part of the global C4 vegetation spread, which occurred around 7 Ma. However, the C4 percentage in ecosystems varied geographically. Despite modern reversal towards C3 habitats due to factors such as increasing CO2, we think that anthropological influences may be responsible for habitat and dietary changes in extant species. Bovids demonstrate the most significant shift in diet and habitat through time, from C4-dominated open habitats to C3-dominated habitats indicative of dense forest understory.

  13. Mitochondrial DNA indicates late pleistocene divergence of populations of Heteronympha merope, an emerging model in environmental change biology.

    Melanie Norgate

    Full Text Available Knowledge of historical changes in species range distribution provides context for investigating adaptive potential and dispersal ability. This is valuable for predicting the potential impact of environmental change on species of interest. Butterflies are one of the most important taxa for studying such impacts, and Heteronympha merope has the potential to provide a particularly valuable model, in part due to the existence of historical data on morphological traits and glycolytic enzyme variation. This study investigates the population genetic structure and phylogeography of H. merope, comparing the relative resolution achieved through partial DNA sequences of two mitochondrial loci, COI and ND5. These data are used to define the relationship between subspecies, showing that the subspecies are reciprocally monophyletic. On this basis, the Western Australian subspecies H. m. duboulayi is genetically distinct from the two eastern subspecies. Throughout the eastern part of the range, levels of migration and the timing of key population splits of potential relevance to climatic adaptation are estimated and indicate Late Pleistocene divergence both of the Tasmanian subspecies and of an isolated northern population from the eastern mainland subspecies H. m. merope. This information is then used to revisit historical data and provides support for the importance of clinal variation in wing characters, as well as evidence for selective pressure acting on allozyme loci phosphoglucose isomerase and phosphoglucomutase in H. merope. The study has thus confirmed the value of H. merope as a model organism for measuring responses to environmental change, offering the opportunity to focus on isolated populations, as well as a latitudinal gradient, and to use historical changes to test the accuracy of predictions for the future.

  14. Analysis of vegetation and climate change during Late Pleistocene from Ziro Valley, Arunachal Pradesh, Eastern Himalaya region

    Bhattacharyya, Amalava; Mehrotra, Nivedita; Shah, Santosh K.; Basavaiah, Nathani; Chaudhary, Vandana; Singh, Indra Bir

    2014-10-01

    Vegetation and climate during later part of Late Pleistocene have been reconstructed from Ziro valley, Arunachal Pradesh, Eastern Himalaya based on pollen data along with carbon isotope and magnetic susceptibility data The study reveals that the area and the vicinity is occupied by mixed broad leaved - conifer forest and pine grass savanah at variable densities at least since 66,000yr BP. The phases of expansions and declines of Oaks with decline and increase of Pines and grasses probably occurred under increase (warm-moist) and decrease (cool-dry) of S.W. monsoon precipitation respectively. The increasing trend of S.W. monsoon and temperature is recorded during ˜44,000 to 34,000 cal yr BP synchronizing with the peat development, and which peaked at around 35,000 cal yr BP. This may link to the interstadial phase during the last major glacial cycle in the Himalayan region. It is also reflected in the decline of δ13C value indicating dominance of C-3 type of vegetation. The increased values of χFD%, and lower values χLF magnetic susceptibility, recorded during the phase of the peat deposit, further advocate's higher monsoon intensity. Impact of expansion of glacier felt with peak (LGM) around 20,000 cal yr BP is perceived. Tree line had moved to lower altitudes due to increased aridity and low temperature. During this time existence of savannah type of vegetation is also evident by the increase of C4 taxa. Decreased FD% and increased χLF susceptibility also indicate reduced S.W. monsoon intensity.

  15. Late Pleistocene (MIS5-3) environmental reconstruction from north-eastern Iberia through microvertebrate and palaeobotanical records

    Allue, Ethel; Bennàssar, Maria; Biltekin, Demet; Blain, Hugues-Alexandre; Burjachs, Francesc; Euba, Itxaso; Expósito, Isabel; Fernández-García, Mónica; López-García, Juan Manuel

    2014-05-01

    The aim of this work is to analyze the environmental changes during the Late Pleistocene on the basis of a multi-approach study based on natural and archaeological deposits from NE Iberian Peninsula. The focussed area, although having a small extension (some 32.000 square kilometres), covers a large range of ecosystems and bioclimatic conditions from the Mediterranean seashore to the summit of the Pyrenean mountain ranges (up to 2000 masl). This synthetical approach includes materials from various contexts including 10 archaeological deposits and a single natural deposit. In this work, plant (pollen and charcoals) and animal (small mammals, amphibians and reptiles) records are being analysed and compared in order to present an overview of the environmental changes occurred from the MIS5 to MIS3. On the first hand, we are using the small-vertebrate records recovered from archaeological deposits. These proxies are mainly the product of pellets from birds of prey and are key ecological markers. On the second hand, palaeobotanical evidences, pollen and charcoal, have different formation processes. Charcoal remains are mostly from archaeological deposits and are due to human activities related to fire showing evidences of the local vegetation. Pollen evidences from archaeological and natural contexts are deposited through natural processes (wind, insects, etc.) and show regional scale vegetation record. Results indicate the presence of temperate elements during all these periods (especially at the seashore area), with a more important representation and extension southwards or changes in altitude from taxa with eurosiberian affinities during coldest periods. Forest coverage, plant and vertebrate distribution along the territory point out a mosaic landscape formed by open areas and forests. These landscapes have probably a more or less Mediterranean or Eurosiberian character depending on the climatic moment and their location with variations along the sequence.

  16. Activity of Changbaishan Tianchi Volcano Since Late Pleistocene--The Constrain From Geochronology of High Precision U- Series Tims Method

    Wang Fei; Chen Wenji; Zhang Zhonglu; Hu Yutai; Peng Zicheng

    2000-01-01

    11 samples of lava and pumice from the cone of Changbaishan Tianchi Volcano, Jiling, China, were dated by using high precision U - series TIMS method. We conclude that the bottom of the cone formed before 350 ka, the middle part in 70~80 ka, the upper during 20~ 1ka, and the top less than 1ka, and the age based periods of the volcano eruption since Late Pleistocene is given as follows: > 350ka, 70ka, 18 ~ 25ka, 10ka, 4C5ka, 1~0.75ka, which may offer the basis for the study of volcanic disaster in future. In addition, the principle of dating young volcanic rocks by using U - series TIMS method is introduced briefly. Differentiation characteristics of U and Th in different minerals of the volcanic rocks are discussed, and the ability producing isochrons, based on U and Th differentiation, are discussed. In the last part of the paper,the closure of samples to the elements U and Th, which is important for age results, is discussed by using (234U/238U)radioactivity ratio which can be used to monitor if the samples have been weathered or eroded or leached since the time they formed. In this study, all samples have (234U/238U) activity ratios within 1% of secular equilibrium ((234U/238U) radioactivity ratios are unity), indicating no disturbance of the 234U- 238U system. All of these discussions show that the TIMS method is good to date Tianchi volcanics and the results are reliable.

  17. The Late Pleistocene and Holocene palaeoenvironmental context of Wonderwerk Cave in the southern Kalahari, South Africa

    Scott, Louis; Avery, Margaret; Bamford, Marion; Berna, Francesco; Brink, James; Brook, George; Chazan, Michael; Ecker, Michaela; Fernandez-Jalvo, Yolanda; Goldberg, Paul; Lee-Thorp, Julia; Rossouw, Lloyd; Thackeray, Francis; Horwitz, Liora

    2014-05-01

    (Stratum 4bII). δ18O values on OES indicate a marked shift to a moister episode in the mid-Holocene between 5.9 and 4.9 ka while pollen, phytoliths and microfauna indicate that more grassy vegetation with woodland developed ~5.5-4.4 ka (Strata 4bI-4aLH, Wilton). A trend towards more arid conditions culminated ~2.8-1.2 ka (Strata 3a-2b, the Ceramic Later Stone Age) as suggested by oxygen and carbon isotopes in OES, and is consistent with pollen and phytolith data indicating vegetation with C4 grasses. The macrofaunal data corroborate this picture, with grassland environments increasing through the Holocene as reflected in an increase in grazers; frequencies of springbok (Antidorcas marsupialis), a species that suggests aridity, rises from 0% in the early Holocene, to 10% in the mid-Holocene, and further to 16% in the Late Holocene. The general arid trend has continued until a slight increase in moisture availability ~0.8 ka leading up to modern semi-arid conditions in the uppermost disturbed strata.

  18. Late Pleistocene Climate Events and The Origin of Agriculture In SW Asia

    Rossignol-Strick, M.

    In the Eastern Mediterranean sea, the climate succession of the last deglaciation is documented and dated in marine cores by the d18-O variation of foraminiferal cal- cite and pollen records. The Last Glacial Maximum is identified by a large abundance of grass pollen from a prairie-type vegetal cover with low annual precipitation in the mountainous north and east borderlands of the sea, where the pollen mainly origi- nates. During the first phase of the last deglaciation, the Bolling/Allerod chronozone, the moisture availability increases and makes possible the spread of a deciduous for- est, as shown by the increasing pollen abundance of the deciduous oak. The cold and arid Younger Dryas is identified by a reversal to semi-desert conditions, with the in- crease of sage-brush (Artemisia) and the saline-tolerant Chenopodiaceae. The climate of the earliest Holocene is Optimum for at least 3000 years (9000-6000yr BP), with the largest spread of the deciduous forest at low-middle elevations signalling wet sum- mers and of the Pistacia woodland at low elevations signalling mild, no-frost winters. This is the time when the most recent sapropel deposited in the eastern Mediterranean under anoxic bottom conditions generated by a surface lid of lower salinity due to the concomitant largest floods of the Nile River fed by the strongest African monsoon rains in the Ethiopian Highlands. In SW Asia, the pollen records of lakes and marshes have been correlated with those of the marine cores, thereby obtaining a robust time-frame. In that area, the archaeo- logical data of human settlements are independently dated by 14C. Thus the archaeo- logical succession can be securely set against the well-dated climatic succession. The Late Palaeolithic populations of SW Asia were wandering hunter-gatherers in the prairies of the Last Glacial Maximum, where they already collected wild wheat, barley and fruit. With the Bolling/Allerod wetter and warmer climate, they began to settle in

  19. Contrasting alluvial architecture of Late Pleistocene and Holocene deposits along a 120-km transect from the central Po Plain (northern Italy)

    Campo, Bruno; Amorosi, Alessandro; Bruno, Luigi

    2016-07-01

    High-resolution investigation of a ~ 120-km-long transect along the course of the modern Po River, northern Italy, revealed marked changes in alluvial architecture across the Pleistocene-Holocene boundary. Along the whole transect, a 20- to 30-m thick sheet-like succession of Late Pleistocene fluvial sands is invariably overlain by silt and clay deposits, with isolated fluvial bodies of Holocene age (architecture: well-drained floodplain deposits are transitional at distal locations to increasingly organic, poorly drained floodplain to swamp facies associations. Thick paludal facies extend continuously up to 60 km landward of the Holocene maximum marine ingression, about 90 km from the modern shoreline. Based on 28 radiocarbon dates, the abrupt change in lithofacies and channel stacking pattern occurred at the transition from the last glacial period to the present interglacial, under conditions of rapid sea-level rise. The architectural change from amalgamated, Late Pleistocene sand bodies to overlying, mud-dominated Holocene units represent an example of chronologically well-constrained fluvial response to combined climate and relative sea-level change. The overall aggradational stacking pattern of individual channel-belt sand bodies indicates that high subsidence rates continuously created accommodation in the Po Basin, even during phases of falling sea level and lowstand.

  20. Integrated well-log, seismic, and biostratigraphic approach to sequence stratigraphy in Late Cenozoic expanded sections, Gulf of Mexico

    Mitchum, R.M. Jr. (R M Mitchum Exploration Inc., Houston, TX (United States)); Sangree, J.B. (Sangree Exploration Inc., Houston, TX (United States)); Vail, P.R. (Rice Univ. Houston, TX (United States)); Wornar, W.W. (Microstrat Inc., Houston, TX (United States))

    1991-03-01

    Increased emphasis on well-log signatures and recognition criteria for stratigraphic sequence boundaries, systems tracts, and condensed sections in a sequence-stratigraphic context has enhanced facies interpretation and reservoir prediction capabilities. Integration of well logs with high-resolution biostratigraphy and paleobathymetry, high-quality seismic configuration data, and the latest eustatic cycle chart provides the best data base for sequence-stratigraphic analysis. This approach is particularly effective for thick, rapidly deposited slope and basin sediments, such as in the Plio-Pleistocene of the Gulf of Mexico basin. The general sequence-stratigraphic model consists of a depositional sequence with lowstand basin floor fan, slope fan, and prograding complex, transgressive systems tract, and highstand systems tract. Each systems tract is deposited at a predictable position in an interpreted eustatic cycle and has recognizable signatures in well logs and seismic data. Any given basin to which this model is applied is strongly controlled by its own tectonic subsidence and accommodation history, and by the type and rate of sediment supply, but the higher frequency eustatic cyclicity is superposed on the other basinal controls. A typical depositional model for the Plio-Pleistocene of the Gulf of Mexico basin is a diapir-controlled subbasin associated with a large contemporaneous expansion fault. The environment of deposition is closely related to the history of fault development. Reservoir sand distribution is characteristic and predictable for each systems tract. Carefully planned evaluation and completion techniques are based on these characteristics.

  1. Precision sequence stratigraphy of the Plio-Pleistocene, Gulf of Mexico: Digital integration of seismic, log, paleontologic, and oxygen isotope data

    Self, G.A.; Butler, M.L. (Amoco Production Co. Research, Tulsa, OK (United States)); Folse, L.W.; Marotta, D.A.; Pratt, D.A. (Amoco Production Co., Houston, TX (United States))

    1991-03-01

    An empirically based (versus a model driven) methodology was developed based on digital integration of seismic data with lithologic, paleontologic, and oxygen isotope data within a computer workstation environment. This flexibility allows the interpreter to visualize the full dynamic range of the seismic data and to manipulate both the temporal and spatial domains. Seven depositional sequences were defined within the Plio-Pleistocene clastic section of the northern Gulf of Mexico basin, offshore Louisiana. Six of these seven sequences are associated with major falls in sea level that occurred at about 200 ka, 500 ka, 900 ka, 1.5 Ma, 2.0 Ma, 2.7 Ma, 3.0 Ma, and 4.5 Ma. Graphic correlation of oxygen isotope stages and foraminiferal climatic assemblages demonstrates that these sequence boundaries developed during third-order cool climatic stages and low sea level. The most sand-rich section was deposited during a significant climatic warm period that developed during the middle Pliocene, prior to the onset of glaciation of the North American continent. During this period, a large delta system prograded across the shelf and deposited significant amounts of sand onto the slope. This occurred in spite of an estimated 35-m sea-level rise above present day. Significant deposition of potential reservoir sands in the slope environment occurs during every subsequent phase of sea-level fluctuation: the result of the interaction between sea-level fluctuation, climatic variations, sedimentary processes, salt tectonics, and basin geometry. The combination of these factors causes wide variation in the timing of sedimentation, as well as the process by which sediments are shed into the slop environment.

  2. Acoustic stratigraphy of Bear Lake, Utah-Idaho: late Quaternary sedimentation patterns in a simple half-graben

    Colman, Steven M.

    2006-01-01

    A 277-km network of high-resolution seismic-reflection profiles, supplemented with a sidescan-sonar mosaic of the lake floor, was collected in Bear Lake, Utah–Idaho, in order to explore the sedimentary framework of the lake's paleoclimate record. The acoustic stratigraphy is tied to a 120 m deep, continuously cored drill hole in the lake. Based on the age model for the drill core, the oldest continuously mapped acoustic reflector in the data set has an age of about 100 ka, although older sediments were locally imaged. The acoustic stratigraphy of the sediments below the lake indicates that the basin developed primarily as a simple half-graben, with a steep normal-fault margin on the east and a flexural margin on the west. As expected for a basin controlled by a listric master fault, seismic reflections steepen and diverge toward the fault, bounding eastward-thickening sediment wedges. Secondary normal faults west of the master fault were imaged beneath the lake and many of these faults show progressively increasing offset with depth and age. Several faults cut the youngest sediments in the lake as well as the modern lake floor. The relative simplicity of the sedimentary sequence is interrupted in the northwestern part of the basin by a unit that is interpreted as a large (4 × 10 km) paleodelta of the Bear River. The delta overlies a horizon with an age of about 97 ka, outcrops at the lake floor and is onlapped by much of the uppermost sequence of lake sediments. A feature interpreted as a wave-cut bench occurs in many places on the western side of the lake. The base of this bench occurs at a depth (22–24 m) similar to that (20–25 m) of the distal surface of the paleodelta. Pinch-outs of sedimentary units are common in relatively shallow water on the gentle western margin of the basin and little Holocene sediment has accumulated in water depths of less than 30 m. On the steep eastern margin of the basin, sediments commonly onlap the hanging wall of the East

  3. A multiproxy reconstruction of the palaeoenvironment and palaeoclimate of the Late Pleistocene in northeastern Iberia: Cova dels Xaragalls, Vimbodí-Poblet, Paratge Natural de Poblet, Catalonia

    López-García, Juan Manuel; Blain, Hugues-Alexandre; Bennàsar, Maria; Euba, Itxaso; Bañuls, Sandra; Bischoff, James; López-Ortega, Esther; Saladié, Palmira; Uzquiano, Paloma; Vallverdú, Josep

    2012-01-01

    The Cova dels Xaragalls is a small open karst system, located in the municipality of Vimbodí-Poblet (Tarragona, Catalonia, NE Spain). It is an important Holocene archaeological site that was inspected in the 1970s but from which little has been published. New excavations starting in 2008 have exposed a deep Late Pleistocene stratigraphical sequence. In this paper, we present for the first time palaeoenvironmental and palaeoclimatic reconstructions of this Late Pleistocene succession on the basis of both the small-vertebrate assemblages and the charcoals. Results from the small-vertebrate associations along the sequence indicate that the landscape had open-woodland habitats in the vicinity of the Cova del Xaragalls, with wet points in the surrounding area. Woodland habitats were dominant throughout the sequence, as evidenced by the abundance of the species Apodemus sylvaticus, but were better developed during warm periods (layers C5 and C8), whereas during cold periods (layers C4 and C3) the environment was slightly more humid in response to higher mean annual precipitation and the opening of the landscape. The charcoal analysis indicates that the woodland surrounding the cave was composed mainly of Pinus (more than 90% was identified as Pinus), but that during the cold period (C3–C4) it incorporated some Quercus ilex/coccifera and Angiosperm indet., probably linked with greater precipitation. Comparisons are made with other long palaeoenvironmental sequences from the northeastern Iberian Peninsula and with global marine isotopic curves, providing a scenario for the palaeoclimatic and palaeoenvironmental changes that occurred during the Late Pleistocene in the woodland areas surrounding the Cova dels Xaragalls.

  4. Late Pleistocene/Holocene paleoclimate reconstruction and eruptive history of Central American volcanoes from lake bottom sediments of Lake Nicaragua

    Wulf, S.; Dull, R. A.; Mann, P.; McIntosh, K. D.; Gardner, J. E.

    2007-12-01

    A shallow coring program in Lake Nicaragua was completed in May/June 2006 by the University of Texas (UT Department of Geography and UT Institute for Geophysics). A total of 35 sediment cores with lengths ranging between 12 cm and 100 cm along with five longer cores were extracted from the lake using a gravity corer and a modified manual square rod piston corer, respectively. Analyses of lake sediments have the following objectives: 1) to correlate the geophysical results with the core data to provide a stratigraphic framework for the shallow lake sediments; 2) to constrain past climate variability in this rather poorly investigated area; and 3) to establish a time series of explosive volcanic activity based on the identification and dating of tephra layers in the cores. Initial measurements of magnetic susceptibility, dry density, loss on ignition and XRF scanning indicated a dominance of fine-grained homogeneous diatomaceous sediments cover most of the lake floor. Increasing values in magnetic susceptibility in the upper part of several short cores most likely reflect increased erosion caused by land-use changes during the Spanish colonial period (1522-1822). Results on the two longest cores from the northeastern (355 cm) and southwestern (478 cm) parts of the lake reveal complete Holocene paleoclimate records in both areas that are comparable to other terrestrial and marine records in the Central and South- American tropics (i.e. Cariaco Basin). A lithologic change from homogeneous gyttia (diatomaceous mud) to blue- grayish waxy clay at the bottom of these records marks the Late Pleistocene-Holocene transition as indicated by a radiocarbon dating on plant remains. The latter dense clay forms a distinctive stratigraphic marker in the lake basin. Tephra layers to date were detected in most gravity cores recovered west of Ometepe Island (Volcan Concepcion), and in long records in the northeastern basin (San Antonio Tephra, Masaya volcano, ca. 7,400 interpolated cal

  5. Late Pleistocene ice export events into the Arctic Ocean from the M'Clure Strait Ice Stream, Canadian Arctic Archipelago

    Stokes, Chris R.; Clark, Chris D.; Darby, Dennis A.; Hodgson, Douglas A.

    2005-12-01

    Rapidly-flowing sectors of an ice sheet (ice streams) can play an important role in abrupt climate change through the delivery of icebergs and meltwater and the subsequent disruption of ocean thermohaline circulation (e.g., the North Atlantic's Heinrich events). Recently, several cores have been raised from the Arctic Ocean which document the existence of massive ice export events during the Late Pleistocene and whose provenance has been linked to source regions in the Canadian Arctic Archipelago. In this paper, satellite imagery is used to map glacial geomorphology in the vicinity of Victoria Island, Banks Island and Prince of Wales Island (Canadian Arctic) in order to reconstruct ice flow patterns in the highly complex glacial landscape. A total of 88 discrete flow-sets are mapped and of these, 13 exhibit the characteristic geomorphology of palaeo-ice streams (i.e., parallel patterns of large, highly elongated mega-scale glacial lineations forming a convergent flow pattern with abrupt lateral margins). Previous studies by other workers and cross-cutting relationships indicate that the majority of these ice streams are relatively young and operated during or immediately prior to deglaciation. Our new mapping, however, documents a large (> 700 km long; 110 km wide) and relatively old ice stream imprint centred in M'Clintock Channel and converging into Viscount Melville Sound. A trough mouth fan located on the continental shelf suggests that it extended along M'Clure Strait and was grounded at the shelf edge. The location of the M'Clure Strait Ice Stream exactly matches the source area of 4 (possibly 5) major ice export events recorded in core PS1230 raised from Fram Strait, the major ice exit for the Arctic Ocean. These ice export events occur at ˜12.9, ˜15.6, ˜22 and 29.8 ka ( 14C yr BP) and we argue that they record vigorous episodes of activity of the M'Clure Strait Ice Stream. The timing of these events is remarkably similar to the North Atlantic's Heinrich

  6. Climate inferences between paleontological, geochemical, and geophysical proxies in Late Pleistocene lacustrine sediments from Summer Lake, Oregon, western Great Basin

    Heaton, Eric; Thompson, Greg; Negrini, Rob; Wigand, Peter

    2016-04-01

    Paleontological, geochemical, and geophysical data from western Great Basin pluvial Summer Lake, Oregon have established a high resolution paleoclimate record during the late Pleistocene Mono Lake Excursion (~34.75 ka), Dansgaard-Oeschger interstadials 6-8, and the end of Heinrich Even 4 (~38 ka). Proxies of grain-size, magnetic susceptibility, carbon/nitrogen ratio, ostracode analysis and palynology from a depocenter core show new results with improved age control regarding high amplitude, high frequency changes in lake level, lake temperature, and regional precipitation and temperature which correspond directly with colder/warmer and respectively drier/wetter climates as documented with Northern Atlantic Greenland ice core data. Results from geophysical and geochemical analysis, and the presence of ostracode Cytherissa lacustris consistently demonstrate the correspondence of low lake conditions and colder water temperatures during Dansgaard-Oeschger stadials and the Mono Lake Excursion. The opposite holds true during interstadials. Smaller grain size, increases in carbon/nitrogen ratio and consistent absence of C. lacustris suggest periods of increased discharge into the lake, increased lake level, and warmer water temperatures. Warmer/wetter climate conditions are confirmed during interstadials 7 and 8 from pollen analysis. Existence of Atriplex, Rosaceae, Chrysothamnus and Ambrosia, and pollen ratios of Juniperus/Dip Pinus and (Rosaceae+Atriplex+Poaceae+Chrysothamnus+Ambrosia)/(Pinus+Picea+T. mertensiana+Sarcobatus) suggest warmer/wetter semi-arid woodland conditions during interstadials 7 and 8. This contrasts with absences in these pollens and pollen ratios indicating colder/drier continental montane woodland conditions during stadials and the Mono Lake Excursion. Increases in Juniper/Dip Pinus ratio suggest a warmer/wetter climate during interstadial 6 however additional proxies do not demonstrate comparative warmer/wetter climate, deeper lake level or

  7. Reconstructed glacier geometry and inferred Equilibrium Line Altitude changes during the Late Pleistocene deglaciation in the Retezat Mountains, Southern Carpathians

    Madarász, Balázs; Ruszkiczay-Rüdiger, Zsófia; Kern, Zoltán; Urdea, Petru

    2016-04-01

    Quaternary glaciations had a major imprint on the landscape and topography of the Southern Carpathians. Their transitional position between continental and Mediterranean climate zones arouses special interest concerning the timing and pattern of glaciations in this area. Probably the Retezat Mts hosted the most extended glaciation during the Late Pleistocene within this range. The peak elevations of the study area reach 2500 m asl, and the most extended glaciers descended to 1040 m in the northern and to 1130 m on the southern valleys. Major cirque floors are typically situated at 2000-2100 m asl. Glacial landforms have been mapped in order to reconstruct the past ice bodies and the elevation shifts of the paleo equilibrium line altitudes (ELA) during several deglaciation phases of the Last Glacial Maximum (LGM) and Lateglacial in the Retezat Mts. On the basis of published 10Be exposure age data on the northern valleys of the study area, deglaciation of the Retezat Mts occurred at least in five phases between ~21.0 ka and 13.5 ka [1]. Various methods (THAR, AAR, AABR) have been tested using a GIS tool to estimate the ELA of the reconstructed paleoglaciers [2] and paleo ELAs were calculated for each of the deglaciation phases. Preliminary estimates of regional LGM paleoELA employing the simplest THAR method (with a ratio of 0.5) ranged from ~1670 m during the LGM to ~2210 m for the smallest cirque glacier at 13.5 ka, respectively. The AAR and AABR methods provide somewhat higher ELAs for each phase. The obtained paleoELAs were compared to ELA reconstructions available from other Carpathian ranges and also to the Alps and Dinarides. Our data will contribute to a more accurate ELA distribution during the LGM, which may be indicative of the past state of the climate system (moisture gradient, circulation regimes). Thanks to OTKA PD83610, PD104899; NKM-96/2014, NKM-31/2015; OMAA 90öu17; LP2012-27/2012. References: [1] Ruszkiczay-Rüdiger et al. 2016 Quat. Int. (in

  8. Long-term hydrological changes in the northeastern Gulf of Mexico (ODP-625B) during the Holocene and late Pleistocene inferred from organic-walled dinoflagellate cysts

    Limoges, Audrey; de Vernal, Anne; Van Nieuwenhove, Nicolas

    2014-01-01

    Palynological analyses are used in conjunction with oxygen isotopes andMg/Ca ratios in foraminifers in order to document the response of dinoflagellate cysts (dinocysts) assemblages to changing climate conditions in the northeastern Gulf of Mexico over the Holocene and late Pleistocene. During MIS...... of P. zoharyi during the Holocene. This likely denotes important differences in the hydrogeographical conditions (e.g. surface circulation, bathymetric configuration) between the present and last interglacial. The importance of environmental parameters other than temperature and salinity for dinocyst...

  9. New Constraints on Late Pleistocene - Holocene Slip Rates and Seismic Behavior Along the Panamint Valley Fault Zone, Eastern California

    Hoffman, W.; Kirby, E.; McDonald, E.; Walker, J.; Gosse, J.

    2008-12-01

    buried by the debris-flow lobe, exhibit progressively larger displacement (up to 10-12 m). Well-preserved bar and swale morphology, incipient varnishing of surface boulders, and weak soil development all suggest that this surface is Late Holocene in age. We are working to confirm this inference, but if correct, it suggests that this fault system may have experienced ~3-4 events in the relatively recent past. Finally, preliminary surface ages from even older surfaces along this portion of the fault zone place limits on the slip rate over Late Pleistocene time. Cosmogenic 10Be surface clast dating of an alluvial surface with well-developed pavement and moderate soil development near Happy Canyon suggests a surface age of 30-35 kyr. We are working to refine this estimate with new dating and soil characterization, but our preliminary reconstructions of displacement of this surface across the two primary fault strands are consistent with slip rates that exceed ~3 mm/yr. Overall, these results are consistent with the inference that the Panamint Valley fault zone is the primary structure that accomplishes transfer of right-lateral shear across the Garlock Fault.

  10. Late Pleistocene and Holocene-Age Columbia River Sediments and Bedforms: Hanford Reach Area, Washington - Part 2

    K.R. Fecht, T.E. Marceau

    2006-03-28

    This report presents the results of a geologic study conducted on the lower slopes of the Columbia River Valley in south-central Washington. The study was designed to investigate glaciofluvial and fluvial sediments and bedforms that are present in the river valley and formed subsequent to Pleistocene large-scale cataclysmic flooding of the region.

  11. The dune systems of the Konya Plain (Turkey): their relation to environmental changes in Central Anatolia during the Late Pleistocene and Holocene

    Kuzucuoglu, C.; Parish, R.; Karabiyikoglu, M.

    1998-06-01

    Several sand flats located on the northern shores of the Late Pleistocene palaeolake of the Konya plain (inner Anatolia, Turkey), are related to changes in lake levels. In this paper, the two main dune systems are mapped according to their geomorphological, sedimentological and dynamic characteristics, and their significance is discussed with regard to the environmental changes since the Late Pleistocene, both at time of the former lake and during the drier periods of the Holocene. Cross-sections show the relationship of the dunes to the topography of the basement. Analyses of the sand fraction show distinct characteristics in size distribution, quartz and shell contents, wind erosion effects on the quartz grains and petrographic composition. Interpretation of the results, coupled with information provided by the geomorphology of the dune systems studied in the field and from aerial photographs and satellite images, highlights the importance and variations in time of local factors such as prevailing winds, sand sources, changes in lake levels and vegetation. A chronology of the main sand fields is proposed, based on the evidence of three main droughts during the Upper Pleistocene. The older one, much eroded (maximum height=3 m), covers a limestone surface at +50 m above the bottom of the dried lake. An Optical Scanning Luminescence (OSL) date shows a last period of accumulation at 14,328±3220 years. The younger one (maximum height=12 m) has moved over the emerged Late Pleistocene lacustrine marls. An OSL date gives an age of 5674±988 years for the last accumulation period. Evidence of very recent activation of this younger dune system is apparent as a result of overgrazing and excessive land reclamation. A third period of dominant wind action and dune construction is responsible for the installation of a younger and thin dune field over the Mid-Holocene lacustrine deposits of the Karapinar lake. The success of the stabilization programme of the dunes over the

  12. Size variation in early human mandibles and molars from Klasies River, South Africa: comparison with other middle and late Pleistocene assemblages and with modern humans.

    Royer, Danielle F; Lockwood, Charles A; Scott, Jeremiah E; Grine, Frederick E

    2009-10-01

    Previous studies of the Middle Stone Age human remains from Klasies River have concluded that they exhibited more sexual dimorphism than extant populations, but these claims have not been assessed statistically. We evaluate these claims by comparing size variation in the best-represented elements at the site, namely the mandibular corpora and M(2)s, to that in samples from three recent human populations using resampling methods. We also examine size variation in these same elements from seven additional middle and late Pleistocene sites: Skhūl, Dolní Vestonice, Sima de los Huesos, Arago, Krapina, Shanidar, and Vindija. Our results demonstrate that size variation in the Klasies assemblage was greater than in recent humans, consistent with arguments that the Klasies people were more dimorphic than living humans. Variation in the Skhūl, Dolní Vestonice, and Sima de los Huesos mandibular samples is also higher than in the recent human samples, indicating that the Klasies sample was not unusual among middle and late Pleistocene hominins. In contrast, the Neandertal samples (Krapina, Shanidar, and Vindija) do not evince relatively high mandibular and molar variation, which may indicate that the level of dimorphism in Neandertals was similar to that observed in extant humans. These results suggest that the reduced levels of dimorphism in Neandertals and living humans may have developed independently, though larger fossil samples are needed to test this hypothesis. PMID:19382177

  13. Mid-late Pleistocene glacial evolution in the Grove Mountains, East Antarctica, constraints from cosmogenic 10Be surface exposure dating of glacial erratic cobbles

    Dong, Guocheng; Huang, Feixin; Yi, Chaolu; Liu, Xiaohan; Zhou, Weijian; Caffee, Marc W.

    2016-08-01

    Glacial histories from the East Antarctic Ice Sheet (EAIS) provide keys to understanding correlations between the EAIS and global climate. They are especially helpful in the assessment of global sea level change, and as a means of quantifying the magnitude of past glacial activity and the rate at which ice responded to climate change. Given the significance of EAIS glacial histories, it is imperative that more glacial chronologic data for this region be obtained, especially for the mid-to-late Pleistocene. We report cosmogenic 10Be surface exposure dating results from glacially transported cobbles embedded in blue-ice moraine material at Mount Harding, the Grove Mountains, EAIS. Forty exotic cobbles sampled along two profiles (A and B) on this blue-ice moraine present apparent exposure-ages ranging from 7.2 to 542.2 ka. We explore this scattered dataset by using Principal Component Analysis (PCA) to identify statistically significant trends in the data. We identify a correlation between exposure-age and distance of the cobbles from Mount Harding. In profile A, cobbles further from Mount Harding yield older exposure-ages than those that are relatively close. In profile B, cobbles closer to Mount Harding are found to have relatively older exposure-ages. In term of glacial history we suggest that the direction of ice flow changed during the period from ∼60 to 200 ka, and that multiple glacial fluctuations occurred in the mid-late Pleistocene.

  14. Progress in the stratigraphy and geochronology of the Shuidonggou site,Ningxia,North China

    LIU DeCheng; WANG XuLong; GAO Xing; XIA ZhengKai; PEI ShuWen; CHEN FuYou; WANG HuiMing

    2009-01-01

    In the past years we carried out further stratigraphy division in field and it is found that rich stone artifacts can be found in fluvial-shallow lake-alluvial sediments on the terrace Ⅱ of Biangou River,in Shuidonggou site,Ningxia and they are SDG1,2 and 7.More luminescence and AMS 14C dating in laboratory show that Paleolithic culture develops during the Upper Paleolithic period with ages of 35-20 ka.The Paleolithic culture of SDG 1 is a little earlier than that of SDG 2 similar to SDG 7.The sandy sediments on terrace Ⅱ of Biangou River deposits in the past 72-18 ka,corresponding to Last Glacial.SDG2 has a stable sedimentary environment,resulting in the continuous stratigraphy,thickest deposits and rich environment and culture information,which can be regarded as the important and classic paleoanthropological section of Late Pleistocene in this region.

  15. Quantification of climate and vegetation from Southern African Middle Stone Age sites - an application using Late Pleistocene plant material from Sibudu, South Africa

    Bruch, A. A.; Sievers, C.; Wadley, L.

    2012-04-01

    The isolated geographical situation of South Africa makes the unraveling of various parameters that influence its regional climate in time challenging. If the South African climate does not exhibit a linear correlation with global archives as suggested by some authors then the contribution of independent local data that provides direct information on the environment at a certain place and time is crucial. Fossil plant remains provide valuable information on past environmental conditions. Although few paleobotanical data are available from Southern Africa, some sites reveal rich and diverse fossil floras, most notably, Sibudu Cave, KwaZulu-Natal, South Africa, with its numerous fruits, seeds, pollen and charcoal flora. Such plant remains not only provide information on past vegetation, but also serve as a sound base for paleoclimate quantification with the Coexistence Approach (CA). Sibudu Cave has pulses of Middle Stone Age occupation separated by hiatuses that are as long as 10 ka. Pre-Still Bay, Still Bay, Howiesons Poort, post-Howiesons Poort and late and final Middle Stone Age industries are present. Variations in vegetation and the animals preyed on through time suggest that subtle environmental changes could have occurred during MIS4 and MIS3 in the Sibudu area. Whilst always semi-forested, the region may have comprised a mosaic of uneven and changeable patches of coastal forest and savanna. These in turn might have influenced the numbers of forest versus plains animals in the area. Cultural factors could also have played a part in the faunal variability observed in Sibudu. Preliminary analyses of Sibudu Cave material confirm the potential of the CA for its application on Late Pleistocene African floras. In the future, comparison with other contemporaneous sites will help quantify spatial differences in the climate of the Late Pleistocene in South Africa, and may answer if environmental changes effected the cultural development from Still Bay to late MSA

  16. Lithology and late postglacial stratigraphy of bottom sediments in isolated basins of the White Sea coast exemplified by a small lake in the Chupa settlement area (Northern Karelia)

    Korsakova, O. P.; Kolka, V. V.; Tolstobrova, A. N.; Lavrova, N. B.; Tolstobrov, D. S.; Shelekhova, T. S.

    2016-05-01

    The complex lithological, geochemical, geochronological, and micropaleontological (diatoms, spores, pollen) investigations of stratified bottom sediments that constitute facies-variable sedimentary sequences in a small isolated lake located near the upper limit of the sea on the White Sea coast made it possible to define lithostratigraphic units (LSU) forming the complete sedimentary succession in deep parts of isolated basins. It is shown that stratigraphy of heterogeneous sequences is determined by two regional transgressive-regressive cycles in relative sea level fluctuations: alternating late Glacial and Holocene transgressions and regressions. The lower part of a clastogenic clayey-sandy-silty sequence successively composed of freshwater (LSU 1) and brackish-water (LSU 2) sediments of the ice-marginal basins and marine postglacial facies (LSU 3) was formed during the late Glacial glacioeustatic marine transgression. Its upper part formed in different isolated basins at different stages of the Holocene is represented depending on its altimetric position on the coastal slope by costal marine sediments (LSU 4) and facies of the partly isolated inlet (LSU 5). The organogenic sapropelic sequence, which overlies sediments of the marine basin and partly isolated bay, corresponds to lithostratigraphic units represented by Holocene sediments accumulated in the meromictic lake (LSU 6), onshore freshwater basin (LSU 7), and freshwater basin with elevated water mineralization (LSU 8) deposited during maximum development of Holocene transgression and lacustrine sediments (LSU 9) formed in coastal environments during terminal phases of the Holocene. The defined lithostratigraphic units differ from each other in lithological, micropaleontological, and geochemical features reflected in structural and textural properties of their sediments, their composition, inclusions, and composition of paleophytocoenoses and diatom assemblages.

  17. The compositional relation of selected clay sediments to late Pleistocene-Holocene depositional environments from Italy and China

    Bonardi, Maurizio; Percival, Jeanne B.; Tosi, Luigi

    1997-01-01

    Mineralogical and textural variations in Upper Pleistocene and Holocene clay sediments from three cores taken in different depositional environments: the Venetian lagoonal littoral zone, the South Yellow Sea and the Yangtze River Delta, are reported. The compositional variations of clay layers from the three sites are attributed to major global climatic changes. Although the compositional difference of clay sediments of the three sites reflects the petrology of their different areas of proven...

  18. A Late Pleistocene palaeoclimate record based on mineral magnetic properties of the entrance facies sediments of Kulna Cave, Czech Republic

    Šroubek, P.; Diehl, J. F.; Kadlec, Jaroslav; Valoch, K.

    2001-01-01

    Roč. 147, č. 2 (2001), s. 247-262. ISSN 0956-540X Grant ostatní: National Science Foundation(US) INT-9507137; National Science Foundation(US) EAR -9705718; Czech/US Jouint Board for Science and Technology(XX) 95051 Institutional research plan: CEZ:AV0Z3013912 Keywords : Kulna Cave * Moravian Karst * Pleistocene Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.366, year: 2001

  19. A long lacustrine record from the Piànico-Sèllere Basin (Middle-Late Pleistocene, Northern Italy)

    A. Moscariello; Ravazzi, C.; Achim Brauer; C. Mangili; Chiesa, S.; Rossi, S.; J.-L. de Beaulieu; M. Reille

    2000-01-01

    The stratigraphical succession of the Piànico-Sèllere Basin (Northern Italy) represents an exceptionally well preserved sedimentary assemblage which formed in a closed lake basin during the Middle–Upper Pleistocene. These deposits are grouped into the hereby proposed "Piànico Formation". This includes four lacustrine, fine-grained, laminated lithostratigraphical units containing a 10.5 m thick interval of well preserved varved carbonates. The lacustrine units are coeval, and laterally heterop...

  20. Chronology and stratigraphy of Late Quaternary sediments in the Konya Basin, Turkey: Results from the KOPAL Project

    Roberts, N.; Black, S.; Boyer, P.; Eastwood, W. J.; Griffiths, H. I.; Lamb, H. F.; Leng, M. J.; Parish, R.; Reed, J. M.; Twigg, D.; Yiǧitbaşioǧlu, H.

    1999-04-01

    The Late Quaternary environmental history of the Konya plain, in south central Turkey, is used to examine sediment facies changes in a shallow non-outlet basin which has experienced major climatically driven changes in lake extent. Two principal types of sedimentary archive are used to reconstruct a palaeoenvironmental record, namely alluvial sequences on the Çarşamba alluvial fan and sediments from residual lakes. The latter have been used to investigate broader climatic and vegetational histories via palaeolimnological techniques including pollen, diatom and stable isotope analysis. These changes are dated here by radiometric techniques including radiocarbon (AMS and conventional), OSL, and U-Th. Chronological agreement is generally good between the different dating techniques, although typically there is greatly reduced precision beyond ca. 25 ka. Lake sediment cores investigated have basal ages beyond the range of 14C dating, but contain hiatuses as a result of subsequent alternation between phases of lacustrine sedimentation and aeolian deflation. In contrast to most deepwater non-outlet lake systems, the Konya basin may have been occupied by a single extensive lake for as little as 10% of Late Quaternary time, mainly around the time of the LGM. This lake highstand was followed by an important arid interval. In the absence of unbroken chronostratigraphic sequences, palaeohydrological investigation of shallow non-outlet lakes may require analysis of basin-wide changes in sedimentation rather than reliance on single core records. Stratigraphic continuity in such sedimentary environments cannot be assumed, and requires independent chronological control through radiometric dating.

  1. The sedimentary sequence from the Lake Ķūži outcrop, central Latvia: implications for late glacial stratigraphy

    Tiiu Koff

    2011-06-01

    Full Text Available Sediment samples from an outcrop in the near-shore area of Lake Ķūži (Vidzeme Heights, Central Latvia were investigated using palaeobotanical (pollen and macrofossil analysis and lithological (grain-size analysis methods and accelerator mass spectrometry 14C dating. A dark, organic-rich sediment layer was found below 1.7 m of sandy layers approximately 30 cm above the present lake level. Radiocarbon dating of a wood sample from the lowermost layer (11 050 ± 60 14C BP, 13 107–12 721 cal BP shows that the layer is of late glacial age. The composition of the pollen spectra is characterized by Betula nana, Cyperaceae pollen and spores of Equisetum, confirming that the lowermost sediments were formed during the late glacial. Fossils of obligate aquatic organisms in the upper layer, which include oospores of Characeae and seeds of Potamogeton, indicate an open water environment. Pollen of Myriophyllum and Potamogeton and non-pollen palynomorphs, such as algal Botryococcus and Pediastrum cf. boryanum, confirm this conclusion. The pollen assemblage from the greyish loam layer following this lacustrine phase shows a pattern characteristic of the Younger Dryas vegetation before the start of the real expansion of birch forests at the beginning of the Holocene.

  2. High-resolution seismic stratigraphy of the late Neogene of the central sector of the Colombian Pacific continental shelf: A seismic expression of an active continental margin

    Martínez, Jaime Orlando; López Ramos, Eduardo

    2011-02-01

    The sedimentary prism of the central Pacific continental shelf of Colombia was affected by regional folding and faulting, and probably later mud diapirism, from the Late Miocene to the Holocene. Interpretation of high-resolution seismic lines (2 s/dt) revealed that the prism consists of 13 high-resolution seismic units, that can be separated into 5 seismic groups. Deposition of the prism and the associated stacking pattern, are probably the response to variable uplift and subsidence in a fore-arc basin that underwent important tectonic events by the end of the Miocene. Throughout the Pliocene, the continental shelf sedimentation was affected by the growing of a dome structure probable due to mud diapirism. This fact caused peripheral faults both normal and reverse that controlled the distribution of some of the seismic units. During the Late Pleistocene (Wisconsin stage?) a eustatic sea level fall caused the shoreline to advance about 50 km westward of its present position. Because of this eustatic sea level change, a strong fluvial dissection took place and is interpreted as the probable extension of the San Juan River to the south of the present day river mouth. Within this framework it is believed that the Malaga and Buenaventura Bays were the passageways of branches of the old drainage system of the San Juan River. The inner branch circulated through the present Buenaventura Bay and runs southward leaving the mark of an apparent valley identified in the seismic information in the eastern sector of the study area. This old fluvial valley and its filling material located in the present day inner continental shelf front of Buenaventura are postulated as important targets to find placer minerals such as gold and platinum.

  3. Late Pleistocene and Holocene tephrostratigraphy of interior Alaska and Yukon: Key beds and chronologies over the past 30,000 years

    Davies, Lauren J.; Jensen, Britta J. L.; Froese, Duane G.; Wallace, Kristi L.

    2016-08-01

    The Aleutian Arc-Alaska Peninsula and Wrangell volcanic field are the main source areas for tephra deposits found across Alaska and northern Canada, and increasingly, tephra from these eruptions have been found further afield in North America, Greenland, and Europe. However, there have been no broad scale reviews of the Late Pleistocene and Holocene tephrostratigraphy for this region since the 1980s, and this lack of data is hindering progress in identifying these tephra both locally and regionally. To address this gap and the variable quality of associated geochemical and chronological data, we undertake a detailed review of the latest Pleistocene to Holocene tephra found in interior Alaska and Yukon. This paper discusses nineteen tephra that have distributions beyond southwest Alaska and that have the potential to become, or already are, important regional markers. This includes three 'modern' events from the 20th century, ten with limited data availability but potentially broad distributions, and six that are widely reported in interior Alaska and Yukon. Each tephra is assessed in terms of chronology, geochemistry and distribution, with new Bayesian age estimates and geochemical data when possible. This includes new major-element geochemical data for Crater Peak 1992, Redoubt 1989-90, and two andesitic tephra from St Michael Island (Tephra D), as well as revised age estimates for Dawson tephra, Oshetna, Hayes set H, Aniakchak CFE II, and the White River Ashes, northern and eastern lobes.

  4. The origin and disappearance of the late Pleistocene-early Holocene short-lived coastal wetlands along the Carmel coast, Israel

    Sivan, Dorit; Greenbaum, Noam; Cohen-Seffer, Ronit; Sisma-Ventura, Guy; Almogi-Labin, Ahuva

    The formation of short-lived backswamps along the Carmel coast of Israel coincides with the rapid global sea-level rise during the late Pleistocene-early Holocene transition. The current study shows that the wetland phenomena originated around 10,000 yr ago and dried up shortly before the local Pre-Pottery Neolithic humans settled on the wetland dark clay sediments 9430 cal yr BP. Palaeontological and stable-isotope data were used in this study to elucidate previously published sedimentological reconstruction obtained from a core drilled into the western trough of the Carmel coastal plain. The water body contained typical brackish calcareous fauna, with variable numerical abundance and low species richness of ostracods and foraminifera. The δ 18O and δ 13C of the ostracod Cyprideis torosa show close similarity to the present Pleistocene coastal aquifer isotopic values. This study therefore concludes that the wetlands were shallow-water bodies fed by groundwater, with no evidence of sea-water mixing. It seems that they developed as the result of high groundwater levels, transportation of sediments landward, and deposition of sand bars at the paleo-river mouths. It is still not fully understood why these wetlands deteriorated abruptly and disappeared within less than 1000 yr.

  5. NEW FOSSIL VERTEBRATE REMAINS FROM SAN GIOVANNI DI SINIS (LATE PLEISTOCENE, SARDINIA: THE LAST MAUREMYS (REPTILIA, TESTUDINES IN THE CENTRAL MEDITERRANEAN

    FRANCESCO CHESI

    2007-07-01

    Full Text Available New fossil vertebrates from the most representative Upper Pleistocene section (Tyrrhenian, MIS 5e of the outcrop of San Giovanni di Sinis (Oristano, Sardinia are here reported and described. The fossils, although scarce and fragmentary, document the occurrence of a terrapin (Mauremys sp. and the endemic Sardinian deer (Praemegaceros cazioti. Significant is the occurrence of the terrapin because it is the youngest representative of the genus in the central Mediterranean area where it is extinct at present. The Late Pleistocene extinction of Mauremys in Italy follows the same pattern of other Mediterranean reptiles, in being in some cases delayed on the islands. A comparison of the modern range of Mauremys and that of the pond turtle, Emys, as well as of their past ranges as evidenced by the fossil record, might suggest that some sort of thermophily (at least during pre-hatching stages characterized the former taxon and is responsible for its past and present distribution. SHORT NOTE

  6. The late Pleistocene horned crocodile Voay robustus (Grandidier & Vaillant, 1872 from Madagascar in the Museum für Naturkunde Berlin

    C. Bickelmann

    2009-02-01

    Full Text Available Crocodylian material from late Pleistocene localities around Antsirabe, Madagascar, stored in the collection of the Museum für Naturkunde, Berlin, was surveyed. Several skeletal elements, including skull bones, vertebrae, ribs, osteoderms, and limb bones from at least three large individuals could be unambiguously assigned to the genus Voay Brochu, 2007. Furthermore, the simultaneous occurrence of Voay robustus Grandidier & Vaillant, 1872 and Crocodylus niloticus Laurenti, 1768 in Madagascar is discussed. Voay robustus and Crocodylus niloticus are systematically separate but similar in stature and size, which would make them direct rivals for ecological resources. Our hypothesis on the extinction of the species Voay, which was endemic to Madagascar, suggests that C. niloticus invaded Madagascar only after V. robustus became extinct. doi:10.1002/mmng.200800007

  7. The Palos Verdes Fault offshore Southern California: Late Pleistocene to present tectonic geomorphology, seascape evolution, and slip rate estimate based on AUV and ROV surveys

    Brothers, Daniel S.; Conrad, James E.; Maier, Katherine L.; Paull, Charles K.; McGann, Mary; Caress, David W.

    2015-07-01

    The Palos Verdes Fault (PVF) is one of few active faults in Southern California that crosses the shoreline and can be studied using both terrestrial and subaqueous methodologies. To characterize the near-seafloor fault morphology, tectonic influences on continental slope sedimentary processes and late Pleistocene to present slip rate, a grid of high-resolution multibeam bathymetric data, and chirp subbottom profiles were acquired with an autonomous underwater vehicle (AUV) along the main trace of PVF in water depths between 250 and 600 m. Radiocarbon dates were obtained from vibracores collected using a remotely operated vehicle (ROV) and ship-based gravity cores. The PVF is expressed as a well-defined seafloor lineation marked by subtle along-strike bends. Right-stepping transtensional bends exert first-order control on sediment flow dynamics and the spatial distribution of Holocene depocenters; deformed strata within a small pull-apart basin record punctuated growth faulting associated with at least three Holocene surface ruptures. An upper (shallower) landslide scarp, a buried sedimentary mound, and a deeper scarp have been right-laterally offset across the PVF by 55 ± 5, 52 ± 4 , and 39 ± 8 m, respectively. The ages of the upper scarp and buried mound are approximately 31 ka; the age of the deeper scarp is bracketed to 17-24 ka. These three piercing points bracket the late Pleistocene to present slip rate to 1.3-2.8 mm/yr and provide a best estimate of 1.6-1.9 mm/yr. The deformation observed along the PVF is characteristic of strike-slip faulting and accounts for 20-30% of the total right-lateral slip budget accommodated offshore Southern California.

  8. Linking Late Pleistocene alpine glacial erosion and continental margin sedimentation: Insights from 40Ar/39Ar dating of silt-sized sediment, Canterbury Basin, New Zealand

    Villaseñor, Tania; Jaeger, John M.; Foster, David A.

    2016-01-01

    Quaternary climatic and eustatic cycles in mid-latitude regions have led to more extensive alpine glaciations and continental shelf progradation, respectively. However, the glacial influence on sediment fluxes to the ocean creating continental margin strata is poorly documented. This contribution analyzes the provenance of fine sediment accumulating on the continental shelf during the Late Pleistocene to evaluate the influence of glacial cycles on sediment erosion and routing to the continental shelf. Taking advantage of the contrasting bedrock ages exposed across the Southern Alps, New Zealand, we perform 40Ar/39Ar incremental heating on the bulk silt-size sediment from three drill sites of IODP Expedition 317, Canterbury Basin, New Zealand. The results suggest that a large proportion of sediment accumulating on the continental shelf results from erosion within the Main Divide fault zone of the Southern Alps. Sediment 40Ar/39Ar age fluctuations over this time period suggest that bedrock with various 40Ar/39Ar cooling ages has been differentially eroded in the upper Waitaki River catchment and mixed in the Waitaki-Canterbury sediment-routing system. Across-shelf variations in sediment 40Ar/39Ar age reflect changing modes of sediment dispersal on the continental shelf. Fluvial material, likely derived from the main drainage divide zone, preferentially accumulates in the middle continental shelf, whereas material representing erosion of older bedrock (Torlesse Terrane), located lower in the drainage basin, is dispersed uniformly across the shelf. The age signature of the muddy sediment accumulating on the continental shelf reflects Late Pleistocene landscape evolution of the Southern Alps and its influence on sediment dispersal to the continental shelf.

  9. Leafcutter bee nests and pupae from the Rancho La Brea Tar Pits of Southern California: implications for understanding the paleoenvironment of the Late Pleistocene.

    Anna R Holden

    Full Text Available The Rancho La Brea Tar Pits is the world's richest and most important Late Pleistocene fossil locality and best renowned for numerous fossil mammals and birds excavated over the past century. Less researched are insects, even though these specimens frequently serve as the most valuable paleoenvironemental indicators due to their narrow climate restrictions and life cycles. Our goal was to examine fossil material that included insect-plant associations, and thus an even higher potential for significant paleoenviromental data. Micro-CT scans of two exceptionally preserved leafcutter bee nest cells from the Rancho La Brea Tar Pits in Los Angeles, California reveal intact pupae dated between ∼23,000-40,000 radiocarbon years BP. Here identified as best matched to Megachile (Litomegachile gentilis Cresson (Hymenoptera: Megachilidae based on environmental niche models as well as morphometrics, the nest cells (LACMRLP 388E document rare preservation and life-stage. The result of complex plant-insect interactions, they offer new insights into the environment of the Late Pleistocene in southern California. The remarkable preservation of the nest cells suggests they were assembled and nested in the ground where they were excavated. The four different types of dicotyledonous leaves used to construct the cells were likely collected in close proximity to the nest and infer a wooded or riparian habitat with sufficient pollen sources for larval provisions. LACMRLP 388E is the first record of fossil Megachile Latreille cells with pupae. Consequently, it provides a pre-modern age location for a Nearctic group, whose phylogenetic relationships and biogeographic history remain poorly understood. Megachile gentilis appears to respond to climate change as it has expanded its distribution across elevation gradients over time as estimated by habitat suitability comparisons between low and high elevations; it currently inhabits mesic habitats which occurred at a lower

  10. Spectral stratigraphy

    Lang, Harold R.

    1991-01-01

    A new approach to stratigraphic analysis is described which uses photogeologic and spectral interpretation of multispectral remote sensing data combined with topographic information to determine the attitude, thickness, and lithology of strata exposed at the surface. The new stratigraphic procedure is illustrated by examples in the literature. The published results demonstrate the potential of spectral stratigraphy for mapping strata, determining dip and strike, measuring and correlating stratigraphic sequences, defining lithofacies, mapping biofacies, and interpreting geological structures.

  11. Late Pliocene and early Pleistocene environments of the north-eastern Russian Arctic inferred from the Lake El'gygytgyn pollen record

    A. A. Andreev

    2013-08-01

    Full Text Available The 318 m thick lacustrine sediment record in Lake El'gygytgyn, northeastern Russian Arctic cored by the international El'gygytgyn Drilling Project provides unique opportunities allowing the time-continuous reconstruction of the regional paleoenvironmental history for the past 3.6 Myr. Pollen studies of the lower 216 m of the lacustrine sediments show their value as an excellent archive of vegetation and climate changes during the Late Pliocene and Early Pleistocene. About 3.50–3.35 Myr BP the vegetation at Lake El'gygytgyn, in nowadays tundra area, was dominated by spruce-larch-fir-hemlock forests. After ca. 3.4 Myr BP dark coniferous taxa gradually disappeared. A very pronounced environmental changes took place at ca. 3.305–3.275 Myr BP, corresponding with the Marine Isotope Stage (MIS M2, when treeless tundra- and steppe-like habitats became dominant in the regional vegetation. Climate conditions were similar to those of Late Pleistocene cold intervals. Numerous coprophilous fungi spores identified in the pollen samples suggest the presence of grazing animals around the lake. Following the MIS M2 event, larch-pine forests with some spruce mostly dominated in the area until ca. 2.6 Myr BP, interrupted by colder and drier intervals ca. 3.04–3.02, 2.93–2.91, and 2.725–2.695 Myr BP. At the beginning of the Pleistocene, ca. 2.6 Myr BP, noticeable climatic deterioration occurred. Forested habitats changed to predominantly treeless and shrubby environments, which reflect a relatively cold and dry climate. Revealed peaks in green algae colonies (Botryococcus around 2.53, 2.45, 2.320–2.305 and 2.175–2.150 Myr BP suggest a spread of shallow water environments. Few intervals (i.e. 2.55–2.53, ca. 2.37, and 2.35–2.32 Myr BP with a higher presence of coniferous taxa (mostly pine and larch document some relatively short-term climate ameliorations.

  12. Late Pliocene and early Pleistocene environments of the north-eastern Russian Arctic inferred from the Lake El'gygytgyn pollen record

    Andreev, A. A.; Tarasov, P. E.; Wennrich, V.; Raschke, E.; Herzschuh, U.; Nowaczyk, N. R.; Brigham-Grette, J.; Melles, M.

    2013-08-01

    The 318 m thick lacustrine sediment record in Lake El'gygytgyn, northeastern Russian Arctic cored by the international El'gygytgyn Drilling Project provides unique opportunities allowing the time-continuous reconstruction of the regional paleoenvironmental history for the past 3.6 Myr. Pollen studies of the lower 216 m of the lacustrine sediments show their value as an excellent archive of vegetation and climate changes during the Late Pliocene and Early Pleistocene. About 3.50-3.35 Myr BP the vegetation at Lake El'gygytgyn, in nowadays tundra area, was dominated by spruce-larch-fir-hemlock forests. After ca. 3.4 Myr BP dark coniferous taxa gradually disappeared. A very pronounced environmental changes took place at ca. 3.305-3.275 Myr BP, corresponding with the Marine Isotope Stage (MIS) M2, when treeless tundra- and steppe-like habitats became dominant in the regional vegetation. Climate conditions were similar to those of Late Pleistocene cold intervals. Numerous coprophilous fungi spores identified in the pollen samples suggest the presence of grazing animals around the lake. Following the MIS M2 event, larch-pine forests with some spruce mostly dominated in the area until ca. 2.6 Myr BP, interrupted by colder and drier intervals ca. 3.04-3.02, 2.93-2.91, and 2.725-2.695 Myr BP. At the beginning of the Pleistocene, ca. 2.6 Myr BP, noticeable climatic deterioration occurred. Forested habitats changed to predominantly treeless and shrubby environments, which reflect a relatively cold and dry climate. Revealed peaks in green algae colonies (Botryococcus) around 2.53, 2.45, 2.320-2.305 and 2.175-2.150 Myr BP suggest a spread of shallow water environments. Few intervals (i.e. 2.55-2.53, ca. 2.37, and 2.35-2.32 Myr BP) with a higher presence of coniferous taxa (mostly pine and larch) document some relatively short-term climate ameliorations.

  13. K-Ar ages and paleomagnetism of Pliocene-Pleistocene pyroclastic rocks from northern Tokachi, Hokkaido

    K-Ar ages were determined on five samples of pyroclastic rocks from northern Tokachi, Hokkaido, and the results were discussed in reference to paleomagnetic, stratigraphic, and paleontological evidence for these rocks. All K-Ar ages obtained are consistent rather well with the stratigraphy and also with the magnetostratigraphy of the rocks. A sample of Meto welded tuff and a rhyolitic welded tuff collected from the downstream of the Osoushi River give nearly the same age of about 2.8 m.y., indicating successive extrusion in the late Pliocene. The Upper Osarushinai Formation is supposed to have been deposited in the early Pleistocene, based on the age obtained from an obsidian clast included in it. The Pliocene-Pleistocene boundary is not defined strictly, but it is supposed to exist in some horizon between the Ikeda and the Upper Osarushinai Formations. (author)

  14. LATE PLEISTOCENE SAND DUNE DEVELOPMENT AND CLIMATIC CHANGES IN THE MU US DESERT,CHINA BASED ON LUMINESCENCE D%石英光释光测年揭示的晚第四纪毛乌素沙地演化

    何忠; 周杰; 赖忠平; 杨林海; 隆浩; 梁剑鸣

    2009-01-01

    climatic change history.Chronological control is crucial in such reconstructions.Desert evolution and climatic change of high resolution in the Mu Us Desert are still poorly understood in part due to limited numerical dating results.In order to further examine the Late Pleistocene sand dune development and climatic changes in this region,five sand dune sections along a northwest-southeast transect in the Mu Us Desert were investigated and sampled.The chronological framework was constructed by dating 19 samples using quartz optically stimulated luminescence(OSL)and single aliquot regenerative-dose(SAR)protocol.A dose recovery test and a preheat plateau showed that the SAR protocol is appropriate for equivalent dose (De)determination for the samples under study.The concentrations of uranium,thorium and potassium were measured by neutron activation analysis.Magnetic susceptibility was measured on a mass of 10g of ground sediment with a Bartington MS2-B Magnetic Susceptibility Meter.The grain size was determined using a Mastersizer-S laser analyzer with(NaPO3)6 as dispersing agent after pretreatment with 10% HCl and 10% H2O2 to remove secondary carbonates and organic material respectively.Combined with lithologic stratigraphy,grain size,magnetic susceptibility and the luminescence chronology obtained,the sand dune development and climatic changes in the Mu Us Desert during the Late Pleistocene are discussed.Aeolian sand layers with wind-ripple lamination imply lower effective moisture,low vegetation cover and sand dune mobilization.The sandy paleosols represent higher effective moisture,higher vegetation cover and weak aeolian activity.Our results indicate that the Mu Us desert experienced multiple alternations of mobile and fixed episodes:the sand was mobilized approximately at 91.0ka,71.0ka,48.0ka,22.Oka,11.6ka,5.0ka,1.1 ka,1.0ka,0.4ka,and was fixed approximately at 65 ka and Holocene optimum period(8.5~5.0ka).The more and thicker sand layers and increasing coarsening of

  15. Equatorial Pacific peak in biological production regulated by nutrient and upwelling during the late Pliocene/early Pleistocene cooling

    J. Etourneau

    2013-08-01

    Full Text Available The largest increase in export production in the eastern Pacific of the last 5.3 Myr (million years occurred between 2.2 and 1.6 Myr, a time of major climatic and oceanographic reorganization in the region. Here, we investigate the causes of this event using reconstructions of export production, nutrient supply and oceanic conditions across the Pliocene–Pleistocene in the eastern equatorial Pacific (EEP for the last 3.2 Myr. Our results indicate that the export production peak corresponds to a cold interval marked by high nutrient supply relative to consumption, as revealed by the low bulk sedimentary 15N/14N (δ15N and alkenone-derived sea surface temperature (SST values. This ∼0.6 million year long episode of enhanced delivery of nutrients to the surface of the EEP was predominantly initiated through the upwelling of nutrient-enriched water sourced in high latitudes. In addition, this phenomenon was likely promoted by the regional intensification of upwelling in response to the development of intense Walker and Hadley atmospheric circulations. Increased nutrient consumption in the polar oceans and enhanced denitrification in the equatorial regions restrained nutrient supply and availability and terminated the high export production event.

  16. Late Pliocene and Early Pleistocene Temperature Reconstructions from Paleolakes of the West Turkana and North Awash Basins, East Africa

    Castañeda, I. S.; Thompson-Munson, M.; Lupien, R.; Russell, J. M.

    2015-12-01

    The Hominin Sites and Paleolakes Drilling Project (HSPDP) aims to reconstruct past environments of the East African Rift Valley from locations in close proximity to some of the world's most important fossil hominin and artifact sites. In this study, we investigate sediments from the West Turkana and North Awash Basins, which were recently drilled as part of the HSPDP. The North Awash Basin contains abundant early hominin fossils and the lakebeds of the Hadar Formation (~3.6 to ~2.9 Ma) will provide a record of climate variability during the Pliocene, prior to the intensification of Northern Hemisphere glaciation at ~2.7 Ma. The lakebeds of the Turkana Basin are Early Pleistocene in age (~1.9 to ~1.45 Ma) and span the interval that includes some the earliest fossils of Homo rudolfensis and H. ergaster/erectus. Here we examine the organic geochemistry of West Turkana and North Awash Basin sediments and investigate the use of proxies based on isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGTs) to reconstruct temperature, including TEX86 and the methylation and cyclization (MBT and CBT) ratios and relative abundances of branched GDGTs. We also examine variability in the abundances and ratios of plant leaf waxes (n-alkanes) to provide insight into past vegetation changes on the East African landscape.

  17. A late-Middle Pleistocene (Marine Isotope Stage 6) vegetated surface buried by Old Crow tephra at the Palisades, interior Alaska

    Reyes, A.V.; Jensen, B.J.L.; Zazula, G.D.; Ager, T.A.; Kuzmina, S.; La, Farge C.; Froese, D.G.

    2010-01-01

    A 40??cm thick primary bed of Old Crow tephra (131??????11??ka), an important stratigraphic marker in eastern Beringia, directly overlies a vegetated surface at Palisades West, on the Yukon River in central Alaska. Analyses of insect, bryophyte, and vascular plant macrofossils from the buried surface and underlying organic-rich silt suggest the local presence of an aquatic environment and mesic shrub-tundra at the time of tephra deposition. Autochthonous plant and insect macrofossils from peat directly overlying Old Crow tephra suggest similar aquatic habitats and hydric to mesic tundra environments, though pollen counts indicate a substantial herbaceous component to the regional tundra vegetation. Trace amounts of arboreal pollen in sediments associated with the tephra probably reflect reworking from older deposits, rather than the local presence of trees. The revised glass fission-track age for Old Crow tephra places its deposition closer to the time of the last interglaciation than earlier age determinations, but stratigraphy and paleoecology of sites with Old Crow tephra indicate a late Marine Isotope Stage 6 age. Regional permafrost degradation and associated thaw slumping are responsible for the close stratigraphic and paleoecological relations between Old Crow tephra and last interglacial deposits at some sites in eastern Beringia. ?? 2009 Elsevier Ltd.

  18. Ice-wedge Pseudomorphs Showing Climatic Change Since the Late Pleistocene in the Source Area of the Yellow River, Northeast Tibet

    CHENG Jie; ZHANG Xujiao; TIAN Mingzhong; YU Wenyang; YU Jiangkuan; TANG Dexiang; YUE Jianwei

    2005-01-01

    The source area of the Yellow River is located in the northeastern Tibetan Plateau, and is a high-elevation region with the annual mean temperature of-3.9℃. The ice-wedge pseudomorphs discovered in this region are recognized as two types.One was found in sandy gravel beds of the second terrace of the Yellow River. This ice-wedge pseudomorph is characterized by higher ratio of breadth/depth, and are 1~1.4 m wide and about 1 m deep. The bottom border of the ice-wedge pseudomorph is round arc in section. Another discovered in the pedestal of the second terrace has lower ratio of width/depth, and is 0.3~1.0 m wide and 1~2 m deep. Its bottom border is sharp. Based on the TL dating, the former was formed at the middle Holocene (5.69±0.43 ka BP and 5.43±0.41 ka BP),that is, the Megathermal, and the latter was formed at the late Last Glacial Maximum (13.49± 1.43 ka BP).Additionally, the thawing-freezing folders discovered in the late Late Pleistocene proluvium are 39.83±3.84 ka BP in age. The study on the ice-wedge pseudomorphs showed that the air temperature was lowered by up to 6~7 ℃ in the source area of the Yellow River when the ice-wedge pseudomorphs and thawing-freezing folds developed.

  19. Humidity changes in southern Tunisia during the Late Pleistocene inferred from U-Th dating of mollusc shells

    Calcareous deposits, mainly consisting of mollusc shell accumulations, which have been dated by the U/Th disequilibrium method, mark the shorelines of paleolake highstands in the Great Chotts Area of Southern Tunisia. The 5 sites studied consist of discontinuous accumulations of fossils of marine-like organisms e.g.: Cerastoderma glaucum, Melania tuberculata, Melanopsis praemorsa, Cerithium rupestre. U/Th isochron plots and age frequency histograms for 39 shell samples are reported here. Limited variations for U content and 234U/238U activity ratios (AR) of shells support the hypothesis of closure of the geochemical system with respect to this element. It is remarkable that 234U/238U AR of shells collected in Chott Fejej or Chott Jerid are clustered around different values, reflecting probably different groundwater recharge from the Continental Intercalaire (CI) or Complexe Terminal (CT) aquifers. Furthermore waters collected near Wadi el Akarit show 234U/238U AR values comparable to those observed for shells. 14C determinations made on aliquots of some of these samples suggested an age distribution between 18 and 34 ka BP. The U/Th data of these 39 shell samples imply that 4 distinct flood episodes of these lakes occurred at about 30, 95-100, 130-150 and 180-200 ka. For the episode centred around 30 ka, the frequency histogram of ages shows a multimodal age group that could represent the existence of several humid pulses rather than a unique event. Moreover, the comparison of δ13C and δ18O with those of older humid Pleistocene phases, when very large palaeolakes have been recorded, suggests that these young carbonate shells are not related to a true highstand lake. It is suggested that they represent a period of less humid climatic conditions with carbonate accumulation in minor water ponds in which intensive biological activity could have taken place. It should be noted that this period was less arid than the present

  20. Correlation of Late Pleistocene Terrestrial Climate Variation From Mono Lake, USA, With Global Records Using Relative Paleointensity

    Zimmerman, S.; Hemming, S.; Kent, D.

    2004-12-01

    In order to assess different models of global climate variation, it is crucial to be able to accurately correlate terrestrial climate records with each other and with marine climate records. This problem is especially challenging in intervals older than 30 kyr, when problems with accuracy and precision of 14C ages become significant. Recently published stacks of global, high-resolution variation in intensity of Earth's past magnetic field (North and South Atlantic PaleoIntensity Stacks, NAPIS and SAPIS) enable correlation of high-quality terrestrial records of paleointensity with the GISP2 timescale. The lacustrine sediments of the Wilson Creek Formation (Mono Basin, CA) are known to be excellent recorders of Pleistocene climate and geomagnetic field variation, and are the type locality for the Mono Lake paleomagnetic excursion (MLE). Here we present rock magnetic analyses showing that the sediments also fit the criteria required for good recorders of paleomagnetic intensity, with a magnetic fraction dominated by fine-grained magnetite with concentration variation lakes of the Great Basin have been shown to be strongly controlled by the 100 ka cycle, and so we infer lake transgression over the Wilson Creek site at the M.I.S. 5/4 boundary, fixing the maximum age of sediment deposition. We then use distinctive features of the Mono and global paleo-intensity records to refine the correlation, resulting in an age of 68 ka for the oldest sediments, and 40 ka for the MLE, coeval with the Laschamp excursion. Finally, we compare climatic proxies measured at Mono to regional and global records, with major changes in glacial proxies at M.I.S. 4/3 boundary and evidence for low lake levels at the time of Heinrich events.

  1. Late Pleistocene leopards across Europe - northernmost European German population, highest elevated records in the Swiss Alps, complete skeletons in the Bosnia Herzegowina Dinarids and comparison to the Ice Age cave art

    Diedrich, Cajus G.

    2013-09-01

    European leopard sites in Europe demonstrate Early/Middle Pleistocene out of Africa lowland, and Late Pleistocene Asian alpine migrations being driven by climatic changes. Four different European Pleistocene subspecies are known. The final European Late Pleistocene “Ice Age leopard” Panthera pardus spelaea (Bächler, 1936) is validated taxonomically. The skull shows heavy signs of sexual dimorphism with closest cranial characters to the Caucasian Panthera pardus ciscaucasica (Persian leopard). Late Pleistocene leopards were distributed northernmost, up to S-England with the youngest stratigraphic records by skeletons and cave art in the MIS 2/3 (about 32,000-26,000 BP). The oldest leopard painting left by Late Palaeolithics (Aurignacians/Gravettians) in the Chauvet Cave (S-France) allows the reconstruction of the Ice Age leopard fur spot pattern being close to the snow or Caucasian leopards. The last Ice Age glacial leopard habitat was the mountain/alpine boreal forest (not mammoth steppe lowland), where those hunted even larger prey such as alpine game (Ibex, Chamois). Into some lairs, those imported their prey by short-term cave dwelling (e.g. Baumann's Cave, Harz Mountains, Germany). Only Eurasian Ice Age leopards specialized, similar as other Late Pleistocene large felids (steppe lions), on cave bear predation/scavenging partly very deep in caves. In Vjetrenica Cave (Dinarid Mountains, Bosnia Herzegovina), four adult leopards (two males/two females) of the MIS 3 were found about two km deep from the entrance in a cave bear den, near to one cave bear skeleton, that remained articulated in its nest. Leopards died there, partly being trapped by raising water levels of an active ponor stream, but seem to have been killed possibly either, similar as for lions known, in battles with cave bears in several cave bear den sites of Europe (e.g. Baumann's Cave, Wildkirchli Cave, Vjetrenica Cave). At other large cave sites, with overlap of hyena, wolf and dhole dens at

  2. Investigations of the Origin of the Magnetic Remanence in Late Pleistocene Lacustrine Sediments in the Mono Basin, CA

    Vasquez, N.; Corley, A. D.

    2015-12-01

    In the Mono Basin, CA, fine sand, silt, and volcanic ash deposited in Pleistocene Lake Russell is exposed on the margin of Mono Lake, and on Paoha Island in the lake. The silt records the Mono Lake Excursion (MLE: Denham and Cox, 1971) and several tens of thousands of years of paleomagnetic secular variation (PSV: Denham and Cox, 1971; Liddicoat, 1976; Lund et al., 1988). The sediment is believed to be an accurate recorder of PSV because the MLE has the same signal at widely separated localities in the basin (Denham, 1974; Liddicoat and Coe, 1979; Liddicoat, 1992) with the exception at wave-cut cliffs on the southeast side of the lake (Coe and Liddicoat, 1994). Magnetite, titanomagnetite, and titanomaghemite are present in the sediment (Denham and Cox, 1971; Liddicoat, 1976; Liddicoat and Coe, 1979), which is glacial flour from the adjacent Sierra Nevada (Lajoie, 1968). X-rays of the sediment and lineation measurements show patterns of normal bedding with layers aligned such that the minimum axes are within 5-10 degrees of normal bedding, with 10 percent foliation and 1 percent lineation (Coe and Liddicoat, 1994). We explore reasons for the difference in part of the PSV record at the wave-cut cliffs beyond the interpretation of Coe and Liddicoat (1994) that paleomagnetic field strength is a controlling factor. Possibilities include the sedimentation rate - at localities on the margin of Mono Lake the rate is about 60 percent less than at the wave-cut cliffs - and lithology of the sediment. At Mill Creek on the northwest side of Mono Lake, the non-magnetic sediment fraction is coarser-grained than at the wave-cut cliffs by a factor of about two, and there is a similar difference in the total inorganic carbon (TIC) percentage by weight for the two localities. (Spokowski et al., 2011) Studies of the sediment at two localities in the basin where the Hilina Pali Excursion (Teanby et al., 2002) might be recorded (Wilson Creek and South Shore Cliffs; Liddicoat and Coe

  3. A reconstruction of late Pleistocene relative sea level in the south Bohai Sea, China, based on sediment grain-size analysis

    Yi, Liang; Yu, Hongjun; Ortiz, Joseph D.; Xu, Xingyong; Qiang, Xiaoke; Huang, Haijun; Shi, Xuefa; Deng, Chenglong

    2012-12-01

    Future anthropogenic sea-level rise and its impact on coastal regions is an important issue facing human civilizations. Due to the short nature of the instrumental record of sea-level change, development of proxies for sea-level change prior to the advent of instrumental records is essential to reconstruct long-term background sea-level changes on local, regional and global scales. Here, we employ numerical methods to partition sediment grain size using a combined database of marine surface and core samples, and to quantitatively reconstruct sea-level variation since the late Pleistocene in the south Bohai Sea, China. Our sea-level reconstruction indicates that relative sea-level changes in the southern Bohai Sea track global sea-level variation for the duration of the record. The results also indicate substantial regression from 70 to 30 cal kyr BP, and potentially subarial exposure from 38 to 20 cal kyr BP. Our results document the feasibility of reconstructing relative sea-level change by numerical partitioning of sediment grain size data, demonstrating the potential for future applications.

  4. A Draft De Novo Genome Assembly for the Northern Bobwhite (Colinus virginianus) Reveals Evidence for a Rapid Decline in Effective Population Size Beginning in the Late Pleistocene

    Halley, Yvette A.; Dowd, Scot E.; Decker, Jared E.; Seabury, Paul M.; Bhattarai, Eric; Johnson, Charles D.; Rollins, Dale; Tizard, Ian R.; Brightsmith, Donald J.; Peterson, Markus J.; Taylor, Jeremy F.; Seabury, Christopher M.

    2014-01-01

    Wild populations of northern bobwhites (Colinus virginianus; hereafter bobwhite) have declined across nearly all of their U.S. range, and despite their importance as an experimental wildlife model for ecotoxicology studies, no bobwhite draft genome assembly currently exists. Herein, we present a bobwhite draft de novo genome assembly with annotation, comparative analyses including genome-wide analyses of divergence with the chicken (Gallus gallus) and zebra finch (Taeniopygia guttata) genomes, and coalescent modeling to reconstruct the demographic history of the bobwhite for comparison to other birds currently in decline (i.e., scarlet macaw; Ara macao). More than 90% of the assembled bobwhite genome was captured within 14,000 unique genes and proteins. Bobwhite analyses of divergence with the chicken and zebra finch genomes revealed many extremely conserved gene sequences, and evidence for lineage-specific divergence of noncoding regions. Coalescent models for reconstructing the demographic history of the bobwhite and the scarlet macaw provided evidence for population bottlenecks which were temporally coincident with human colonization of the New World, the late Pleistocene collapse of the megafauna, and the last glacial maximum. Demographic trends predicted for the bobwhite and the scarlet macaw also were concordant with how opposing natural selection strategies (i.e., skewness in the r-/K-selection continuum) would be expected to shape genome diversity and the effective population sizes in these species, which is directly relevant to future conservation efforts. PMID:24621616

  5. Late Pleistocene glaciation in the Central Andes: Temperature versus humidity control — A case study from the eastern Bolivian Andes (17°S) and regional synthesis

    Kull, C.; Imhof, S.; Grosjean, M.; Zech, R.; Veit, H.

    2008-01-01

    A glacier-climate model was used to calculate climatic conditions in a test site on the east Andean slope around Cochabamba (17°S, Bolivia) for the time of the maximum Late Pleistocene glaciation. Results suggest a massive temperature reduction of about - 6.4 °C (+ 1.4/- 1.3 °C), combined with annual precipitation rates of about 1100 mm (+ 570 mm/- 280 mm). This implies no major change in annual precipitation compared with today. Summer precipitation was the source for the humidity in the past, as is the case today. This climate scenario argues for a maximum advance of the paleo-glaciers in the eastern cordillera during the global Last Glacial Maximum (LGM, 20 ka BP), which is confirmed by exposure age dates. In a synthesized view over the central Andes, the results point to an increased summer precipitation-driven Late Glacial (15-10 ka BP) maximum advance in the western part of the Altiplano (18°S-23°S), a temperature-driven maximum advance during full glacial times (LGM) in the eastern cordillera, and a pre- and post-LGM (32 ka BP/14 ka BP) maximum advance around 30°S related to increased precipitation and reduced temperature on the western slope of the Andes. The results indicate the importance of understanding the seasonality and details of the mass balance-climate interaction in order to disentangle drivers for the observed regionally asynchronous past glaciations in the central Andes.

  6. Late Pliocene - Early Pleistocene geologic history of Eastern Ledi-Geraru, Ethiopia: implications for the evolution of the southern Afar Depression and hominin paleoenvironments

    DiMaggio, E.; Arrowsmith, R.; Campisano, C. J.; Reed, K.; Deino, A.

    2012-12-01

    During the late Pliocene and early Pleistocene (~ 3-2.5 Ma), the Afar region of Ethiopia was undergoing major structural reorganization (e.g., change in extension direction, increased spreading rate) leading to significant landscape modification. Concurrent with these changes in paleogeography, regional trends towards a cooler and drier climate coincide with a clustering of first appearance and extinction events in the faunal record, including the diversification of the early hominin genus Australopithecus and the emergence of our own genus, Homo. However, sediments that span the 3 to 2.5 Ma interval are sparse in eastern Africa, and are especially rare at paleoanthropological sites in the Afar. Here we present new geologic mapping results that indicate extensive deposits of late Pliocene sediments in a previously unmapped region of the lower Awash Valley referred to as the Eastern Ledi-Geraru (ELG). Numerous interbedded airfall tephras enable geochemical comparisons to the existing regional tephrostratigraphic framework as well as high precision 40Ar/39Ar dating of tephras with suitable feldspars. Feldspars from 8 such tephra deposits span the time period of 3.0 to 2.8 Ma, providing the first glimpse of depositional environments and associated landscapes that existed at that time. Geologic mapping and stratigraphic analysis shows that over a 100 meter thick section of lacustrine to fluvial sediments are exposed along faulted basalt flows following both the Red Sea Rift and Main Ethiopian Rift structural trends. We interpret the geology at ELG to reflect a northeastern migration of paleo Lake Hadar, possibly into a series of smaller basins responding to the migration of the triple junction, a thinning lithosphere, and an increased period of volcanism. Combined with recently collected paleontological assemblages this work provides an opportunity to test proposed links between biotic events, global/regional climate change, and local tectonic events during a critical

  7. A late Pleistocene refugium in Mediterranean North Africa? Palaeoenvironmental reconstruction from stable isotope analyses of land snail shells (Haua Fteah, Libya)

    Prendergast, A. L.; Stevens, R. E.; O'Connell, T. C.; Hill, E. A.; Hunt, C. O.; Barker, G. W.

    2016-05-01

    The late Pleistocene to Holocene archaeological record of North Africa is key to understanding the emergence of anatomically modern humans into West Asia and Europe, and the broadening of subsistence strategies in the shift from hunter-gatherer to pastoral-agricultural lifeways. Some contend that these developments were modulated by major shifts in climate and environment. Evaluation of this hypothesis requires the pairing of local and regional climate records with well-dated archaeological sequences. The Haua Fteah archaeological site in the Gebel Akhdar region of Libya provides a key site to test this hypothesis as the cave contains one of the longest and most complete sequences of human occupation in North Africa as well as abundant material for palaeoenvironmental reconstruction. This study uses stable isotope analyses (δ18O and δ13C) of the terrestrial mollusc Helix melanostoma to construct a palaeoenvironmental framework for interpreting North African human-environment interactions from the Upper Palaeolithic to the Neolithic (∼30,000 to 5000 years ago). The land snail stable isotope records from Haua Fteah suggests that cool arid conditions in the cave peaked during marine isotope stage (MIS) 2. This stage was, however, only marginally drier than previous and subsequent stages and coincided with an increase in occupation density in the cave. This suggests that the Gebel Akhdar may have served as an environmental refugium from the more extreme aridity in the surrounding Sahara and arid coastal plains for Late Stone Age (LSA) populations in North Africa. Conditions became progressively wetter towards the Holocene. However, generally wetter conditions were interrupted by two arid episodes at c. 8.0 ka and 7.3 ka that appear to coincide with regional changes reflected elsewhere in the Mediterranean basin.

  8. Comparison of Geochemical, Grain-Size, and Magnetic Proxies for Rock Flour and Ice- Rafted Debris in the Late Pleistocene Mono Basin, CA

    Zimmerman, S. H.; Hemming, S. R.; Kent, D. V.

    2008-12-01

    Advance and retreat of mountain glaciers are important indicators of climate variability, but the most direct proxy record, mapping and dating of moraines, is by nature discontinous. The Sierra Nevada form the western boundary of the Mono Lake basin, and the proximity of the large Pleistocene lake to the glacial canyons of the Sierra presents a rare opportunity to examine glacial variability in a continuous, well-dated lacustrine sequence. We have applied a geochemical proxy for rock flour to the glacial silts of the late Pleistocene Wilson Creek Formation, but because it is time- and sample-intensive, another method is required for a high-resolution record. Previous microscopic examination, thermomagnetic measurements, XRD analysis, and new isothermal remnant magnetization (IRM) acquisition curves show that the magnetic mineralogy is dominated by fine-grained, unaltered magnetite. Bulk measurements show strong susceptibility (mean ~ 16 x 10- 6 m3/kg) and remanent magnetization (mean IRM ~ 10-2 Am2/kg) compared to diluting components (carbonate, smectite, rhyolitic ash). The Wilson Creek type section sediments also contain a coarse lithic fraction, quantified by counting the >2cm clasts in outcrop and the >425 μm fraction in the bulk sediment. Susceptibility, IRM, and ARM (anhysteretic remnant magnetization) are quite similar throughout the type section, with the abundance of coarse lithic fraction correlative to the ratio k/IRM. Because the magnetic fraction of the rock flour is fine-grained magnetite, IRM should capture the changes in concentration of flour through time, and the major features of the (low-resolution) geochemical flour proxy record are identifiable in the IRM record. Flux-correction of the IRM results in a rock flour proxy record with major peaks between 36 and 48 ka, similar to a rock flour record from neighboring Owens Lake. This regional glacial signal contrasts with peaks in coarse lithics between 58 and 68 ka in the Wilson Creek record

  9. Estimation of the shortening rate since late Pleistocene in the Aksu area on the southern flank of the Tianshan, China

    WANG; Xin

    2001-01-01

    [1]Molnar, P., Tapponnier, P., Cenozoic tectonics of Asia: Effects on a continental collision, Science, 1975, 189: 419-426.[2]Molnar, P., Deng Qidong, Faulting associated with large earthquakes and the average rate of deformation in central and eastern Asia, J. Geophys. Res., 1984, 89: 6203-6227.[3]Hendrix, M. S., Dumitru, T. A., Graham, S. A., Late Oligocene-early Miocene unroofing in the Chinese Tianshan: An early effect of the India-Asia collision, Geology, 1994, 22: 487-490.[4]Sobel, R. E., Dumitru, T. A., Thrusting and exhumation around the margins of the western Tarim Basin during the India-Asia collision, J. Geophys. Res., 1997, 102: 5043-5063.[5]Ghose, S., Hamburger, M. W., Virieux, J., Three-dimentional velocity structure and earthquake locations beneath the northern Tianshan of Kyrgyzstan, central Asia, J. Geophys. Res., 1998, 103: 2725-2748.[6]Ghose, S., Hamburger, M. W., Ammon, C. J., Source parameters of moderate-sized earthquakes in the Tianshan, central Asia from regional moment tensor inversion, Geophys. Res. lett., 1998, 25: 3181-3184.[7]Abdrakhmatov, K. Ye, Aldazhanov, S. A., Hager, B. H. et al., Relatively recent construction of the Tianshan inferred from GPS measurements of present-day curstal deformation rates, Nature, 1996, 384: 450-452.[8]Wang Qi, Ding Guoyu, Qiao Xuejun et al., Present-day Tianshan's quick shortening and the south-north block's relative movement, Chinese Science Bulletin (in Chinese), 2000, 45(14): 1543-1547.[9]Zhu Wenyao, Wang Xiaoya, Chen Yuyi et al., Crustal motion of Chinese mainland monitored by GPS, Science in China, Ser. D, 2000, 43(2): 394-400.[10]Avouac, J. P., Tapponnier, P., Bai, M. et al., Active thrusting and folding along the northern Tianshan and late cenozoic rotation of the Tarim relative to Dzungaria and Kazakhstan, J. Geopgys. Res., 1993, 98: 6755-6804.[11]Burtman, V. S.,Skobelev, S. F., Molnar, P., Late cenozoic slip on the Talas-Ferghana fault, the Tianshan

  10. Reconstruction of mass balance of Nevado Coropuna glaciers (Southern Peru) for Late Pleistocene, Little Ice Age and the present.

    Ubeda, J.; Palacios, D.

    2009-04-01

    The Nevado Coropuna volcanic complex (15th 31'S-72 ° 39 ° W) is the quaternary stratovolcano northernmost of the central volcanic zone (CVZ) in the western flank of the Central Andes (Southern Peru). This consists in four adjacent volcanic buildings that are occupied over 5.100-5.700 masl by a system of glaciers covering an area of 47 Km2 in 2007 (Ubeda et al, 2008). The maximum expansion of glaciers during the Pleistocene affected an area of ~449 Km2, dropping to altitudes around 3.600-4800 m (Ubeda et al, 2007). In this work were mapped several hundreds of moraines which constitute a record of climate change since the last glacial maximum (LGM). Current glacier system is formed by dozen of glaciers descending slope down in all directions. Coropuna complex is an excellent laboratory for to investigate the control that climate change, tectonics and volcanism exert on the dynamics of glaciers, a scale of tens of years (by studying current glaciers) and also of tens of thousands of years (by analyzing the geomorphological evidence of its evolution in the past). Ubeda et al. (2008) analyzed the evolution of eighteen glaciers of Nevado Coropuna using indicators as surfaces and Equilibrium Line Altitudes (ELAs) of ice masses in 2007, 1986, 1955, Little the Ice Age (LIA) and Last Glacial Maximum (LGM). The glaciers were grouped into two sets: NE group (seven glaciers) and SE group (eleven glaciers). The work included statistical series of ELAs in each phase, estimates by Area x Altitud Balance Ratio (AABR) method, which was proposed by Osmaston (2005), in addition with estimates of timing (~17Cl36 Ka) and magnitude (~ 782-911 m) of ELA depression during LGM. The work included statistical series of ELAs in each phase, estimates by the method Area x Altitud Balance Ratio (AABR) proposed by Osmaston (2005), and in addition estimates of the timing (~17Cl36 Ka) and magnitude (~ 782-911 m) of ELA depression during LGM. The objective of this work is to estimate the current

  11. The influence of Late Pleistocene geomorphological inheritance and Holocene hydromorphic regimes on floodwater farming in the Talgar catchment, southeast Kazakhstan, Central Asia

    Macklin, Mark G.; Panyushkina, Irina P.; Toonen, Willem H. J.; Chang, Claudia; Tourtellotte, Perry A.; Duller, Geoff A. T.; Wang, Hong; Prins, Maarten A.

    2015-12-01

    In comparison to Southwest Asia and the Indian subcontinent, the relationship between Holocene river dynamics, climate change and floodwater farming in Central Asia is significantly under researched. To address this, a multi-disciplinary research project was begun in 2011 centred on the Talgar catchment, a south-bank tributary of the Ili River, southeast Kazakhstan. Building on archaeological excavations and surveys conducted over the past 20 years, we have undertaken investigations of Holocene human adaptations to changing hydromorphic regimes in the Tien Shan piedmont region, Central Asia. Fluvial geochronologies have been reconstructed over the last 20,000 years using Optically Stimulated Luminescence and 14C dating, and are compared with human settlement histories from the Eneolithic to the medieval period. Phases of Late Pleistocene and Holocene river aggradation at c. 17,400-6420, 4130-2880 and 910-500 cal. BC and between the mid-18th and early 20th centuries were coeval with cooler and wetter neoglacial episodes. Entrenchment and floodplain soil development (c. 2880-2490 cal. BC and cal. AD 1300-1640) coincided with warmer and drier conditions. Prior to the modern period, floodwater farming in the Talgar River reached its height in the late Iron Age (400 cal. BC - cal. AD 1) with more than 70 settlement sites and 700 burial mounds. This period of agricultural expansion corresponds to a phase of reduced flooding, river stability and glacier retreat in the Tien Shan Mountains. Late Iron age agriculturists appear to have been opportunistic by exploiting a phase of moderate flows within an alluvial fan environment, which contained a series of partially entrenched distributary channels that could be easily 'engineered' to facilitate floodwater farming. Holocene climate change was therefore not a proximate cause for the development and demise of this relatively short-lived (c. 200 years) period of Iron Age farming. River dynamics in the Tien Shan piedmont are

  12. Speculation on the timing and nature of Late Pleistocene hunter-gatherer colonization of the Tibetan Plateau

    P. J. Brantingham; MA Haizhou; J. W. Olsen; GAO Xing; D. B. Madsen; D. E. Rhode

    2003-01-01

    Hunter-gatherer populations in greater northeast Asia experienced dramatic range expansions during the early Upper Paleolithic (45-22 ka) and the late Upper Paleolithic (18-10 ka), both of which led to intensive occupations of cold desert environments including the Mongolian Gobi and northwest China. Range contractions under the cold, arid extremes of the Last Glacial Maximum (LGM, 22-18 ka) may have entailed widespread population extirpations. The high elevation Qinghai-Tibetan Plateau is significantly more extreme in both climate and environment than either the Gobi or the Siberian taiga forests, and provides an ideal setting to test fundamental models of human biogeog-raphy in the context of regional population fluctuations. The area is presently occupied primarily by nomadic pastoralists, but it is clear that these complex middle Holocene (<6 ka) economic adaptations were not a necessary prerequisite for successful colonization of the high elevation Plateau. Exploratory field-work in 2000-2001 has established that Upper Paleolithic hunter-gatherers were present on the Qinghai-Tibetan Plateau by at least 12 ka and possibly much earlier. Aspeculative model for the colonization process is developed and preliminary archaeological data in support of the model are presented.

  13. Variability of the Arabian Sea upwelling and intensity of the oxygen minimum zone over the late Pleistocene and Holocene

    Gaye, Birgit; Böll, Anna; Rixen, Tim; Emeis, Kay-Christian; Ramaswamy, Venkitasubramani

    2016-04-01

    The northern Arabian Sea is one of the main oceanic regions with a permanent low oxygen layer at intermediate water depth that results in water column denitrification. While glacial/interglacial variations in the Arabian Sea oxygen minimum zone (OMZ) are relatively well studied, little is known about the spatial and temporal extent of mid-water oxygen throughout the Holocene. We compared alkenone derived sea surface temperatures of the last 25 kyrs from a core in the northern Arabian Sea with a core from the monsoonal upwelling area off Oman. The difference between the two temperature reconstructions indicates that monsoonal upwelling occurred during warm interstadials and during the entire Holocene. δ15N curves show that denitrification also matched with monsoonal upwelling. Comparison of δ15N records from different locations in the Arabian Sea reveal a Holocene shift in the location of the core OMZ from the northwestern (early Holocene) to the northeastern Arabian Sea (late Holocene). This shift was caused by (i) spatial differences in oxygen demand, caused by changes in SW- and NE-monsoon intensities and associated productivity changes, as well as (ii) changes in mid-water ventilation facilitated by sea level rise and inflow of Persian Gulf and Red Sea Water leading and changes of ventilation by Indian Ocean Central Water .

  14. Late Pliocene to early Pleistocene (2.4-1.25 Ma) paleoproductivity changes in the Bering Sea: IODP expedition 323 Hole U1343E

    Kim, Sunghan; Khim, Boo-Keun; Takahashi, Kozo

    2016-03-01

    Late Pliocene to early Pleistocene paleoproductivity changes in the Bering Sea were reconstructed using geochemical concentrations and mass accumulation rates (MARs) of CaCO3, biogenic opal, and total organic carbon (TOC), and sedimentary nitrogen isotope ratios (δ15N) at IODP Expedition 323 Hole U1343E, drilled in the northern slope area (1956 m deep) of the Bering Sea. CaCO3 concentration is generally low, but prominent CaCO3 peaks occur intermittently due to subseafloor authigenic carbonate formation rather than biogenic accumulation, regardless of glacial-interglacial variations. Biogenic opal concentrations reflect orbital-scale glacial-interglacial variations. However, TOC concentration did not show clear glacial-interglacial variation, probably due to poor preservation. The sedimentary δ15N values vary synchronously with biogenic opal concentration on orbital timescales. The co-varying pattern of opal productivity and δ15N values at Hole U1343E is a result of nutrient utilization controlled by diatom productivity in the Bering slope area where Fe is not a limiting factor. Biogenic opal and TOC MARs showed a temporal shift at around 1.9 Ma from a high productivity period under nutrient-enriched conditions to a low productivity period under relatively nutrient-depleted conditions. High diatom productivity with low δ15N values before 1.9 Ma is associated with abundant nutrient supply by upwelling in relation to strong surface current system. This productivity decrease at about 1.9 Ma was also found in the southern Bering Sea (Site U1341) and may be related to global opal reorganization.

  15. Inconsistent Climate Inferences between Pollen and other Paleontological, Geochemical, and Geophysical Proxies in Late Pleistocene Lacustrine Sediments from Summer Lake, Oregon, Western Great Basin

    Heaton, E.; Thompson, G.; Negrini, R. M.; Wigand, P. E.

    2015-12-01

    This study has established a high resolution paleoclimate record from western Great Basin pluvial Summer Lake, Oregon during the late Pleistocene Mono Lake Excursion (~34 ka), Dansgaard-Oeschger (D-O) interstadials 7 and 8, and the end of Heinrich Even 4 (~38 ka). Proxies of grain-size, carbon/nitrogen (C/N) ratio, ostracode analysis and palynology from a depocenter core show new results regarding high amplitude, high frequency changes in lake level, precipitation and temperature which correspond directly with colder/warmer and respectively drier/wetter climates as documented with Northern Atlantic Greenland ice core data. The granulometry, geochemical, and ostracode results consistently demonstrate the correspondence of low lake conditions and colder water temperatures during D-O stadials and warmer/wetter climate during interstadials. These results are contradicted by the pollen results. Existence of cold temperature spores Botrychium and Selaginella coincide with increases in Artemisia, Atriplex, Sarcobatus, Cyperaceae and decreases in Pinus, also suggesting periods of colder/drier climate and shallower lake levels but the timing does not match that of those conditions inferred by the other methods. Granulometry, geochemical, and ostracode proxies denote cold periods and low lake levels roughly between 37.5-35.6 ka and 34.6-33.8 ka. Pollen analysis suggests near-opposite time intervals with cold periods roughly 38-37.5 ka, 35.6-35 ka. This pollen inconsistency suggests the possibility of (1) a millennial-scale lag response of vegetation to climate change, (2) runoff from stadial precipitation causing influx in pollen abundances and variety found in the depocenter core, or (3) turbulent mixing from shallow lake level causing resuspension and redeposition of pollen (Bradley 1999).

  16. Palaeovegetation dynamics of an ecotone forest-savanna in southern Brazilian Amazon during the late Pleistocene and Holocene based on carbon isotopes of soil organic matter

    This study was carried out in the Brazilian southern Amazon region (Rondonia state and Humaita, southern Amazon state). Carbon isotope data on soil organic matter have been collected along an ecosystem transect of about 750 km that includes a savanna, a wooded savanna (cerrado), a tropical semideciduous forest (cerradao), a forest transition type and a tropical forest. The main objective is to evaluate the expansion-regression dynamics of these vegetation units in relation to climate changes during the Late Pleistocene (Late Glacial) and Holocene. Large ranges in δ13 values were observed in soil organic matter collected from profiles in the savanna (-27 to -14 per mille and forest regions (-26 to -19 per mille) reflecting changing distribution of 13C-depleted C3 forest and 13C enriched C4 savanna vegetation in response to climate change. 14C data of humin fraction and buried charcoal indicate that the organic matter in these soils is at least 17,000 years BP at 300-cm depth. In this period, the entire ecosystem transect are characterized by δ13C soil depth profiles, generated typically by C3 plants (forest), inferring a humid climate in the southern Amazon region after the end of last glaciation. 13C data also indicate that C4 plants (grasses) have influenced significantly the vegetation at the transitional forest and the cerrado sites of southern Rondonia state and two distinct points in the forest ecosystem in the southern Amazon state. These typical C4 type isotopic signatures probably reflect a drier climate during about 9000-8000 yr BP to 3000 yr BP and the savanna and wooded savanna expansion in distinct points of the transect. The 13C records representing the 3000 yr show an expansion of the forest, due to a climatic improvement, in areas previously occupied by savanna vegetation. This study adds to the mounting evidence that extensive forested areas existed in the Amazon during the last glacial and that savanna vegetation expanded in response to warm and

  17. Late Pleistocene-Holocene uplift driven terrace formation and climate-tectonic interplay from a seismically active intraplate setting: An example from Kachchh, Western India

    Prizomwala, S. P.; Das, Archana; Chauhan, G.; Solanki, T.; Basavaiah, N.; Bhatt, Nilesh; Thakkar, M. G.; Rastogi, B. K.

    2016-07-01

    terrace, we reported a minimum uplift rate of 1.04 mm/a for the eastern KMF during the Late Pleistocene-Holocene period, hinting seismically active nature of the KMF during this period. The terrace formation in the eastern Northern Hill Range is mostly regulated by tectonic uplifts along the KMF.

  18. Reconstruction of Equilibrium Line Altitudes of Nevado Coropuna Glaciers (Southern Peru) from the Late Pleistocene to the present

    Úbeda, J.; Palacios, D.; Vázquez, L.

    2009-04-01

    The Nevado Coropuna (15°31'S-72°39'W) is a volcanic complex located 200 km NE of the city of Arequipa, in the Southern Peruvian Andes. The summit area in the complex is covered with a glacier system formed by dozens of branches descending in all directions totaling many km2 in surface area. The study of the volcanic complex and its glaciers is of great interest because it is the main water reserve for tens of thousands of people, because of the risk scenario created by the presence of ice masses on a volcano with relatively recent activity, and because it constitutes an excellent geoindicator of the effects of climate change on ice masses in the western mountain chain of the Central Andes. This research aims to analyze glacier evolution using as geoindicators variations in glacier surface and equilibrium line altitudes (ELAs), defining deglaciation rates based on those variations and preparing forecasts with them on when the ice masses might disappear if the same rates were to occur in the future. In addition, a first estimation is attempted of the chronologies of the last phase of volcanic activity and the last phase of maximum glacier advance that can be attributed to the Late Glacial or Last Glacial Maximum periods. To achieve these aims, digital topography with 50m contour interval, two orthophotos of the central section of the Coropuna complex (15-6-1955 and 21-10-1986), an ASTER satellite image (12-11-2007) and geomorphological mapping of the volcanic complex created in a previous phase of the research (Ubeda, 2007) were integrated into a Geographical Information System (GIS). The GIS was used to determine the global extent of the glacier system, and in more detail, that of two groups (NE and SE) in 1955, 1986 and 2007. Using the geomorphological cartography as a basis, the extent of the glaciers during their last advance in the Little Ice Age (LIA) and their last maximum advance were calculated. Next, surface areas for all phases were calculated using

  19. Late Pleistocene to early Holocene aeolian and flash-flood sedimentation and soil formation in a small hilly catchment in SW-Germany (Palatinate forest)

    Dotterweich, M.; Kühn, P.; Tolksdorf, J. F.; Müller, S.; Nelle, O.

    2012-04-01

    . The layers are overlain by very clear visible wavy and frequently distributed clay-illuviation bands typical for a Luvisol. The upper meter looks duller and more homogenous which is typical for a Bv-horizion of a Cambisol. The embedded deposition shows structures in this sediment package that are typical for a flash-flood event. Records of soil erosion during this time period are sparse and it is generally assumed that sediments were fixed by forest vegetation. In contrast, these presented results indicate that the manipulation of forest vegetation by fire by sedentary Mesolithic hunter-gatherers created an open area and enabled soil erosion with a high geomorphological impact on a local scale. This geoarchive provides first time high resolution data on a natural (and anthropogenic) soil-sediment formation during the Late Pleistocene and Early Holocene in SW-Germany.

  20. Influence of Late Pleistocene and Holocene climate on vegetation distributions in southwest Africa elucidated from sedimentary n-alkanes - Differences between 12°S and 20°S

    Badewien, Tanja; Vogts, Angela; Dupont, Lydie; Rullkötter, Jürgen

    2015-10-01

    Global and local climatic forcing, e.g. concentration of atmospheric CO2 or insolation, influence the distribution of C3 and C4 plants in southwest Africa. C4 plants dominate in more arid and warmer areas and are favoured by lower pCO2 levels. Several studies have assessed past and present continental vegetation by the analysis of terrestrial n-alkanes in near-coastal deep sea sediments using single samples or a small number of samples from a given climatic stage. The objectives of this study were to evaluate vegetation changes in southwest Africa with regard to climatic changes during the Late Pleistocene and the Holocene and to elucidate the potential of single sample simplifications. We analysed two sediment cores at high resolution, altogether ca. 240 samples, from the Southeast Atlantic Ocean (20°S and 12°S) covering the time spans of 18 to 1 ka and 56 to 2 ka, respectively. Our results for 20°S showed marginally decreasing C4 plant domination (of ca. 5%) during deglaciation based on average chain length (ACL27-33 values) and carbon isotopic composition of the C31 and C33n-alkanes. Values for single samples from 18 ka and the Holocene overlap and, thus, are not significantly representative of the climatic stages they derive from. In contrast, at 12°S the n-alkane parameters show a clear difference of plant type for the Late Pleistocene (C4 plant domination, 66% C4 on average) and the Holocene (C3 plant domination, 40% C4 on average). During deglaciation vegetation change highly correlates with the increase in pCO2 (r² = 0.91). Short-term climatic events such as Heinrich Stadials or Antarctic warming periods are not reflected by vegetation changes in the catchment area. Instead, smaller vegetation fluctuations during the Late Pleistocene occur in accordance with local variations of insolation.

  1. Pollen and lithological data from the Bukovynka Cave deposits as recorders of the Late Pleistocene and Holocene climatic change in the eastern foothills of the Carpathian Mountains (Ukraine

    Nataliia GERASIMENKO

    2015-11-01

    Full Text Available The study of clastic sediments of the BukovynkaCaveshows biotic and climatic changes during the Middle Pleniglacial (the Trapeznyi Chamber, Late Glacial and Holocene (the Sukhyi Chamber in the south-eastern part of the Ukrainian Carpathians. The artesian BukovynkaCaveis located near the villageof Stal’nivtsi(the Chernivtsi region, in the PrutRiver basin. It is developed in the Miocene gypsum strata. The Quaternary clastic infilling of the cave, as well as mammal taphonomy has been previously studied in the Trapeznyi Chamber (Vremir et al., 2000; Ridush, 2004; Ridush et al., 2012, whereas palaeomagnetic research and its palaeoenvironmental implication has been provided for the Sukhyi Chamber (Bondar and Ridush, 2014. The results of pollen and grain-size studies of clastic deposits in both chambers, supported by mammal finds, are presented in this paper. In the Chernivtsi region, the pollen study has been previously performed (without 14C-dating on the Upper Pleistocene loess-paleosol section of Snyatyn and on the Onut site of the Holocene flood-plain deposits of the River Prut (Artyushenko et al., 1982. 39 samples from the cave sediments have been processed for grain-size analyses using the ‘pipette’ technique by Kachinsky (1965. In order to get pollen from clastic sediments, the following technique has been applied: heating with 10% HCl and 10% KOH, cold treatment with HF, disintegration in a solution of Na4P2O7 and separation in heavy liquid (CdI2 and KI with a specific gravity 2.2. The abundance and good preservation of pollen show that the cave chambers turned periodically into sedimentation traps. Mammal bones are also mostly well preserved. Re-deposited pollen are abundant in the Trapeznyi Chamber but occur very rarely in the Suchyi Chamber. The present-day vegetation near the cave is a meadow-steppe surrounded by Carpinus-Quercus forest. The high proportion of Pinus sylvestris pollen in the surface soil samples (30-40% does not

  2. Facies and depositional sequences of the Late Pleistocene Göçü shoreline system, Konya basin, Central Anatolia: Implications for reconstructing lake-level changes

    Karabiyikoǧlu, Mustafa; Kuzucuoǧlu, Catherine; Fontugne, Michel; Kaiser, Brigitte; Mouralis, Damase

    1999-04-01

    Well-developed coarse-grained palaeo-shoreline deposits are found along the rising margins of the Konya basin, marking the former extent of a now desiccated Late Pleistocene lake. This study evaluates the depositional environments and the sequential evolution of a shoreline system that developed at the northern margin of the Konya palaeolake near Göçü. Several laterally continuous quarry sections provided an excellent opportunity for studying spatial and temporal changes of depositional environments and related lake-level fluctuations. Eight principal sedimentary facies and six major lithostratigaphic units have been identified in these deposits representing progradational and retrogradational episodes of shoreline development. The lowest sequence is an aggradational unit formed by wind-driven currents and waves in a sand-dominant lake bottom above the wave base. It is overlain by a convoluted palaeosol 14C dated to ca 28,300 BP representing a major lowering of lake levels. Following an unconformity, the next sequence is characterised by large-scale gravelly clinoforms that progressively offlap/downlap onto the underlying sequence, and correspond to progradation of a foreshore resulting from storm-originated oscillating and unidirectional currents, avalanching processes and minor subaqueous debris flows. It is overlain by an areally extensive lensoid body of structureless clays comprising a thin organic layer, abundant rootlets and freshwater mollusc shells, formed from suspension fallout in a quiet, very shallow freshwater lagoonal environment. This phase, representing a more minor lake regression, has been 14C dated to ca. 21,960-20,730 BP. The final sequences include large-scale sand waves and bars, which developed by storm-originated wave surges and strong shoreline currents, and prograding delta foresets. These sequences indicate a renewed lake transgression to higher water levels, before a final regression after 17,500 BP. Lack of tectonic deformation and

  3. Late Pleistocene/Early Holocene Migratory Behavior of Ungulates Using Isotopic Analysis of Tooth Enamel and Its Effects on Forager Mobility.

    Pilaar Birch, Suzanne E; Miracle, Preston T; Stevens, Rhiannon E; O'Connell, Tamsin C

    2016-01-01

    Zooarchaeological and paleoecological investigations have traditionally been unable to reconstruct the ethology of herd animals, which likely had a significant influence on the mobility and subsistence strategies of prehistoric humans. In this paper, we reconstruct the migratory behavior of red deer (Cervus elaphus) and caprids at the Pleistocene-Holocene transition in the northeastern Adriatic region using stable oxygen isotope analysis of tooth enamel. The data show a significant change in δ18O values from the Pleistocene into the Holocene, as well as isotopic variation between taxa, the case study sites, and through time. We then discuss the implications of seasonal faunal availability as determining factors in human mobility patterns. PMID:27275784

  4. Late Pleistocene/Early Holocene Migratory Behavior of Ungulates Using Isotopic Analysis of Tooth Enamel and Its Effects on Forager Mobility

    Pilaar Birch, Suzanne E.; Miracle, Preston T.; Stevens, Rhiannon E.; O’Connell, Tamsin C.

    2016-01-01

    Zooarchaeological and paleoecological investigations have traditionally been unable to reconstruct the ethology of herd animals, which likely had a significant influence on the mobility and subsistence strategies of prehistoric humans. In this paper, we reconstruct the migratory behavior of red deer (Cervus elaphus) and caprids at the Pleistocene-Holocene transition in the northeastern Adriatic region using stable oxygen isotope analysis of tooth enamel. The data show a significant change in δ18O values from the Pleistocene into the Holocene, as well as isotopic variation between taxa, the case study sites, and through time. We then discuss the implications of seasonal faunal availability as determining factors in human mobility patterns. PMID:27275784

  5. The Late Pleistocene-Holocene community development in Central and SE-Europe in direct fossil record: scope of the approach, common patterns and inter-regional differences.

    Horacek, Ivan; Lozek, Vojen

    2010-05-01

    The information provided by modern instrumental approaches (molecular phylogeography, ancient DNA analyses, large scale radiocarbon datings etc.) refined the knowledge on Late Quaternary faunal development and range history of particular taxa in essential way. Nevertheless, the direct fossil record remains still an essential substrate in study of that topics, and to reveal all the information, that it may provide, and integrate it with the outputs of the other approaches presents one of the essential aim of the present meeting. Unfortunately, the immediate use of fossil record for the paleoecologic and paleobiogeographic inferences is often limited by its fragmentarity (both in temporal and spatial respects), taphonomic influences and/or locally specific post-sedimentary effects which all may bias it in a considerable degree. Hence, each particular record is to be carefully reexamined in respect to all factor which may bias it - unfortunately, often it is not too easy to respond that task, particularly when the record is retrived from secondary sources. It should also be remembered that the records representing narrow time slices without a robust lithostratigraphic context do not provide any information on the historical and contextual setting of the respective faunal situation. Such information that is essential for reconstructions of paleobiogeography of community development and similar locally-sensitive phenomena can only be retrived from the continuous sedimentary series which establish the sequence of particular faunal events by direct superposition. A sufficiently dense network of such series provides than a possibility of direct inter-regional comparisons and a high resolution information on the paleobiogeography of the Late Pleistocene-Holocene rearrangements of mammalian communities, local variation in history of particular species and its community context. We illustrate productivity of such approach on with aid of the fossil record obtained from

  6. HISTORICAL GEOLOGY &STRATIGRAPHY

    2012-01-01

    <正>20122559 Chen Fangwen ( College of Earth Sciences,Northeast Petroleum University,Daqing 163318,China );Lu Shuangfang High-Resolution Sequence Stratigraphy and Sedimentary Characteristics of the Fuyu Oil-Bearin Layers in the Wangfu Depression ( Journal of Stratigraphy,ISSN0253-4959,CN32-1187 / P,35 ( 4 ), 2011,p.368-374,3illus.,14refs. ) Key words:Cretaceous,high resolution sequence stratigraphy,Songliao Plain

  7. The presence of Ursus ex gr. minimus-thibetanus in the late villányian and its position among the Pliocene and Pleistocene black bears in Europe

    Wagner, Jan; Čermák, Stanislav; Horáček, I.

    -, č. 4 (2011), s. 39-58. ISSN 1771-1150 R&D Projects: GA ČR GA205/09/0184 Institutional research plan: CEZ:AV0Z30130516 Keywords : Black bear * MN17 * Ursus aff. thibetanus * Villány 3 * Central Europe - Hungary * Ursus * Pleistocene * Pliocene Subject RIV: DB - Geology ; Mineralogy

  8. Neogene-Quaternary tectonic stratigraphy of the eastern Southern Alps, NE Italy

    Caputo, R.; Poli, M. E.; Zanferrari, A.

    2010-07-01

    In order to reconstruct the Neogene-Quaternary Tectonic Stratigraphy of the eastern Southern Alps, the late Tortonian-lower Pleistocene foredeep clastic sequences, cropping out in the Veneto and Friuli piedmont areas have been extensively investigated focusing on the contractional features observed in the frequent conglomerate layers (pitted pebbles). The eastern Southern Alps is the result of a typical polyphase tectonic activity initiated in Late Oligocene, characterised by the occurrence of several non-coaxial stress regimes. Based on careful analyses of the pebbles' surfaces (shape and orientation of the indented features) and following a systematic and statistical approach, the mean orientation of the maximum compressive stress axis (σ 1) has been obtained for more than 30 sites of measurements along the ca. 120 km-long investigated piedmont area. The affected lithostratigraphic units and the orientation (pre- versus post-tilting) of the stereonets density peaks make it possible to recognize four distinct deformational events and characterize them in terms of mean σ 1 direction and timing: late Tortonian ( σ1 = 313°/00°), late Messinian-Early Pliocene (338°/04°), Late Pliocene (314°/03°), and Early-Middle Pleistocene (160°/03°). The Tectonic Stratigraphy of the eastern Southern Alps during the last ca. 10 Ma shows the occurrence of several variations of the stress field characterized by a repeated oscillation of the σ 1 axis between an NNW-SSE and NW-SE directions (Twist Tectonics). Taking also into account literature data about older deformational events (Chattian-Burdigalian and Serravallian-Tortonian), we analyse the Neogene-Quaternary tectonic evolution in the frame of the central Mediterranean realm and compare it with the convergence direction between the Adria-Africa and Europe lithospheric plates. We show that compressional directions within the eastern Southern Alps are basically governed by the remote plate convergence, though since late

  9. Contribution to the stratigraphy of the onshore Paraiba Basin, Brazil

    Rossetti, Dilce F.; Valeriano, Marcio M., E-mail: rossetti@dsr.inpe.br [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Divisao de Sensoriamento Remoto; Goes, Ana M.; Brito-Neves, Benjamim B. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Inst. de Geociencias; Bezerra, Francisco H.R.; Ochoa, Felipe L. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Centro de Ciencias Exatas e da Terra. Departamento de Geologia

    2012-06-15

    Several publications have contributed to improve the stratigraphy of the Paraiba Basin in northeastern Brazil. However, the characterization and distribution of sedimentary units in onshore areas of this basin are still incomplete, despite their significance for reconstructing the tectono- sedimentary evolution of the South American passive margin. This work provides new information to differentiate among lithologically similar strata, otherwise entirely unrelated in time. This approach included morphological, sedimentological and stratigraphic descriptions based on surface and sub-surface data integrated with remote sensing, optically stimulated luminescence dating, U+Th/He dating of weathered goethite, and heavy mineral analysis. Based on this study, it was possible to show that Cretaceous units are constrained to the eastern part of the onshore Paraiba Basin. Except for a few outcrops of carbonatic-rocks nearby the modern coastline, deposits of this age are not exposed to the surface in the study area. Instead, the sedimentary cover throughout the basin is constituted by mineralogically and chronologically distinctive deposits, inserted in the Barreiras Formation and mostly in the Post-Barreiras Sediments, of early/middle Miocene and Late Pleistocene-Holocene ages, respectively. The data presented in this work support tectonic deformation as a factor of great relevance to the distribution of the sedimentary units of the Paraiba Basin. (author)

  10. Chronology of the shell bar section and a discussion on the ages of the Late Pleistocene lacustrine deposits in the paleolake Qarhan,Qaidam basin

    2008-01-01

    Shell bar,composed of abundant fossil shells of Corbicula fluminea müller and Corbicula largillierti philippi and located at the southeastern end (36°30'N,96°12'E) of the paleolake Qarhan,is one of the most prominent features in the Qaidam basin.It is the highest site where such species of fossil shells have been found in the Late Pleistocene age.A 2.6-m-thick fresh profile was manually excavated to determine the formation ages and the scope of the high paleolake levels.Accelerator mass spectrometry (AMS),conventional radiocarbon dating,and sector inductively coupled plasma-mass spectroscopy 230Th methods were used to investigate the reliability and accuracy of dating results in different laboratories.Ages of various components (e.g.acid residual and acid soluble fraction of the organic matter) from the same sample were determined.Age differences of a variety of materials (e.g.organic matter,fossil shells,and salt crystals),and age differences at the same sampling position were evaluated.Dating shows that the AMS ages given by alkali residue and acid soluble fractions vary greatly,e.g.,from 124.5 cm upwards.The dates given by the acid soluble fraction were normal.Down the column,the dates show a reverse pattern and those of alkali residues,especially the lower part of the section,show an unstable pattern.These imply that organic matter had been influenced by two separate processes.One possible explanation is that the alkali residual fraction most likely had been contaminated by dead carbon-bearing reworked material because the study section is located near the edge of the paleolake and could have been easily influenced by old eroded deposits.Another is that the acid soluble fraction could have been contaminated by upward-flowing groundwater containing soluble organic matter.The amount of this soluble organic material should be very small because the strongest age reversal is in the lower part,where the TOC content remains low,meaning that the change of soluble

  11. Late Cretaceous-Early Palaeogene echinoderms and the K/T boundary in the southeast Netherlands and northeast Belgium - Part 1: Introduction and stratigraphy

    Jagt, J.W.M.

    1999-01-01

    In a series of papers describing Late Cretaceous and Early Palaeogene echinoderm faunas (exclusiveof holothurians) of the Maastrichtian type area, the present contribution comprises a detailed accountof the litho- and chronostratigraphy and biozonations of these deposits, and of localities from whic

  12. HISTORICAL GEOLOGY & STRATIGRAPHY

    2014-01-01

    <正>20142287Cao Changqun(State Key Laboratory of Paleobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,CAS,Nanjing 210008,China);Zhang Mingyuan The Permian Capitanian Stratigraphy at the Rencunping Section,Sangzhi County of Hunan Province and Its Environmental Implications

  13. Late Pleistocene variations in Antarctica sea ice. I - Effect of orbital isolation changes. II - Effect of interhemispheric deep-ocean heat exchange

    Crowley, Thomas J.; Parkinson, Claire L.

    1988-01-01

    A dynamic-thermodynamic sea-ice model is presently used to ascertain the effects of orbitally-induced insolation changes on Antarctic sea-ice cover; the results thus obtained are compared with modified CLIMAP reconstructions of sea-ice 18,000 years ago. The minor influence exerted by insolation on Pleistocene sea-ice distributions is attributable to a number of factors. In the second part of this investigation, variations in the production of warm North Atlantic Deep Water are proposed as a mechanism constituting the linkage between climate fluctuations in the Northern and Southern hemispheres during the Pleistocene; this hypothesis is tested by examining the sensitivity of the dynamic-thermodynamic model for Antarctic sea-ice changes in vertical ocean heat flux, and comparing the simulations with modified CLIMAP sea-ice maps for 18,000 years ago.

  14. Late Mesozoic to Paleogene stratigraphy of the Salar de Atacama Basin, Antofagasta, Northern Chile: Implications for the tectonic evolution of the Central Andes

    Mpodozis, Constantino; Arriagada, César; Basso, Matilde; Roperch, Pierrick; Cobbold, Peter; Reich, Martin

    2005-04-01

    The Salar de Atacama basin, the largest "pre-Andean" basin in Northern Chile, was formed in the early Late Cretaceous as a consequence of the tectonic closure and inversion of the Jurassic-Early Cretaceous Tarapacá back arc basin. Inversion led to uplift of the Cordillera de Domeyko (CD), a thick-skinned basement range bounded by a system of reverse faults and blind thrusts with alternating vergence along strike. The almost 6000-m-thick, upper Cretaceous to lower Paleocene sequences (Purilactis Group) infilling the Salar de Atacama basin reflects rapid local subsidence to the east of the CD. Its oldest outcropping unit (Tonel Formation) comprises more than 1000 m of continental red sandstones and evaporites, which began to accumulate as syntectonic growth strata during the initial stages of CD uplift. Tonel strata are capped by almost 3000 m of sandstones and conglomerates of western provenance, representing the sedimentary response to renewed pulses of tectonic shortening, which were deposited in alluvial fan, fluvial and eolian settings together with minor lacustrine mudstone (Purilactis Formation). These are covered by 500 m of coarse, proximal alluvial fan conglomerates (Barros Arana Formation). The top of the Purilactis Group consists of Maastrichtian-Danian alkaline lava and minor welded tuffs and red beds (Cerro Totola Formation: 70-64 Ma K/Ar) deposited during an interval of tectonic quiescence when the El Molino-Yacoraite Late Cretaceous sea covered large tracts of the nearby Altiplano-Puna domain. Limestones interbedded with the Totola volcanics indicate that this marine incursion advanced westwards to reach the eastern CD slope. CD shortening in the Late Cretaceous was accompanied by volcanism and continental sedimentation in fault bounded basins associated to strike slip along the north Chilean magmatic arc to the west of the CD domain, indicating that oblique plate convergence prevailed during the Late Cretaceous. Oblique convergence seems to have

  15. Mars Stratigraphy Mission

    Budney, C. J.; Miller, S. L.; Cutts, J. A.

    2000-01-01

    The Mars Stratigraphy Mission lands a rover on the surface of Mars which descends down a cliff in Valles Marineris to study the stratigraphy. The rover carries a unique complement of instruments to analyze and age-date materials encountered during descent past 2 km of strata. The science objective for the Mars Stratigraphy Mission is to identify the geologic history of the layered deposits in the Valles Marineris region of Mars. This includes constraining the time interval for formation of these deposits by measuring the ages of various layers and determining the origin of the deposits (volcanic or sedimentary) by measuring their composition and imaging their morphology.

  16. A continent-wide framework for local and regional stratigraphies

    Gijssel, Kier van

    2006-01-01

    This study is part of an interdisciplinary project dealing with the Palaeolithic occupation phases of northern Europe. In order to give feedback on the time control over the scattered Palaeolithic evidence, the thesis is focused on the (chrono)stratigraphy of the terrestrial Middle Pleistocene succession, spanning the period from approximately 780,000 to 130,000 years ago. Its record, including the Palaeolithic archeological record, is fragmentary and heterogeneous both in time and space. Int...

  17. Stratigraphy, fossils, and age of sediments at the upper pit of the Lost Chicken gold mine: new information on the late Pliocene environment of east central Alaska

    Matthews, John V., Jr.; Westgate, J. A.; Ovenden, Lynn; Carter, L. David; Fouch, Thomas

    2003-07-01

    The "upper pit" at the Lost Chicken placer gold mine in east central Alaska contains fossils that provide information on the flora and insect fauna of interior Alaska just before the onset of global cooling at 2.5 myr. Fossils come from sediments interbedded with the Lost Chicken tephra (dated at 2.9 ± 0.4 myr—early Late Pliocene) and portray the floodplain and valley of a small creek within a region dominated by a coniferous forest richer in genera and species than the present one. Climate was wetter and less continental, and there was probably little or no permafrost. At least one other Pliocene tephra (the Fortymile tephra) occurs at the site and is also associated with plant and insect fossils. Among these fossils are extinct plants and insects like those found at other Tertiary sites in northern Canada and Alaska. The Lost Chicken sequence is the same age as the Beaufort Formation on Meighen Island, more than 1000 km to the north. Like Lost Chicken, Meighen Island sediments contain fossils representing a diverse boreal environment. This shows that the latitudinal climate gradient during early Late Pliocene time was shallower than at present and the boreal forest had a far greater latitudinal span than now.

  18. Orogénesis y drenaje en la región del Valle de Lerma (cordillera oriental, Salta, Argentina durante el Pleistoceno Tardío Orogeny and drainage in the Lerma Valley region (Eastern Cordillera, Salta, Argentina during the late Pleistocene

    Gustavo González Bonorino

    2012-03-01

    Mojotoro and Castillejo ranges. Contraction gave rise to the interior Vaqueros Range and the San Mguel Hills, and then propagated eastward with a regional reverse fault that derived in the development of the Mojotoro and Castillejo ranges and closure of the Lerma Valley. Some river courses incised across the rising barriers, whereas others were diverted to an internally drained basin flooded by ancient Lake Lerma. Incision power was greater in the northern Lerma Valley, where the rivers reached the sites of topographic uplift with high bed gradients, and where the Mojotoro River persisted as an antecedent course. In the south, Lake Lerma filled the basin to a pour point through structural lows in Salta Group strata, and the issuing water carved the subsequent channel of the present Juramento River across the Castillejo Range. More than 800 m of sediment (herein designated Lerma Valley Group accumulated in the Lerma Valley during the late Pleistocene. Subsurface information allowed a critical revision of the stratigraphy of this fill and a more detailed subdivision. In particular, the geographical extension of the Tajamar Formation is restricted and previously proposed extrapolations for it are revised.

  19. Late Pleistocene to Holocene alluvial tableland formation in an intra-mountainous basin in a tectonically active mountain belt ― A case study in the Puli Basin, central Taiwan

    Tseng, Chia-Han; Lüthgens, Christopher; Tsukamoto, Sumiko; Reimann, Tony; Frechen, Manfred; Böse, Margot

    2016-01-01

    The morphology in Taiwan is a product of high tectonic activity at the convergent margin and East Asian monsoon climate. Tablelands are prominent geomorphic features in the Puli Basin in central Taiwan. These tablelands provide an archive to understand links between past climatic evolution and tectonic events resulting in the formation of the present-day landforms. To establish a geochronological framework for the alluvium underlying the tablelands in the Puli Basin, optically stimulated luminescence dating was applied to obtain burial ages. The numerical data indicate an accumulation phase of alluvial fans in the Late Pleistocene to Early Holocene transition. The study area in the Taomi River catchment, an obvious longer precursor of the Taomi River, originating from west of the Yuchih Basin, transported the sediments forming the present-day southern tablelands. During the Pleistocene-Holocene transition, the climate changed to wetter and warmer conditions, so that slope processes might have changed and an increasing transport in the fluvial system was stimulated. Fluvial and fan terraces in other river catchments in Taiwan also indicate a period of increased fluvial transport and deposition. A geomorphic evolution model in the Puli Basin is reconstructed on the basis of the chronological framework and of sedimentological features. Fluvial processes controlled by climatic change and accompanied by tectonic activities have created the diverse topography in the Puli Basin.

  20. Late Pleistocene steppe lion Panthera leo spelaea (Goldfuss, 1810) footprints and bone records from open air sites in northern Germany - Evidence of hyena-lion antagonism and scavenging in Europe

    Diedrich, Cajus G.

    2011-07-01

    Bone remains and a trackway of Pantheraichnus bottropensis nov. ichg. ichnsp. of the Late Pleistocene lion Panthera leo spelaea ( Goldfuss, 1810) have been recovered from Bottrop and other open air sites in northern Germany. Some of these bones are from open air hyena den sites. A relative high proportion of lion bones (20%) exhibit bite, chew or nibble marks, or bone crushing and nibbling caused by a large carnivore. Repeated patterns of similar bone damage have been compared to bone remains found at hyena dens in gypsum karst areas and cave sites in northern Germany. Ice Age spotted hyenas have been the main antagonists and the main scavengers on lion carcasses. The remains appear to have been imported often by hyenas into their communal dens, supporting the theory of strong hyena-lion antagonism, similar to the well documented antagonism between modern African lions and spotted hyenas. Most of the lion bones from the open air hyena den at Bottrop are probably a result of such antagonism, as are the rare remains of these carnivores found within large hyena prey bone accumulations along the Pleistocene rivers. The Emscher River terrace also has the largest quantity of hyena remains from open air river terrace sites in northern Germany. Their cub remains, and incomplete chewed prey bones from mammoths and woolly rhinoceroses, typical of hyena activity, underline the character of these sites as cub-raising and communal dens, where their prey was accumulated along the riverbanks in a similar manner to modern African hyenas.

  1. Did humans cause the Late Pleistocene-Early Holocene mammalian extinctions in South America in a context of shrinking open areas?

    Tonni, Eduardo Pedro; Cione, Alberto Luis; Soibelzon, Leopoldo Héctor

    2008-01-01

    The last important –and possibly the most spectacular– turnover in South American mammal history occurred around the Pleistocene-Holocene boundary, when 100% of megamammal species and about 80% of large mammal species became extinct. In this paper, we consider as “megamammals” those with body mass over 1,000 kg, and “large mammals” those over 44 kg. With the exception of a few smaller mammals, no other animal or plant disappeared. Consequently, this extinction event was distinct from mass ext...

  2. Stratigraphy and structural geology

    Carr, M. H.; Wilhelms, D. E.; Greeley, R.; Guest, J. E.

    1976-01-01

    The immediate goal of stratigraphy and structural geology is to reduce the enormous complexity of a planetary surface to comprehensible proportions by dividing the near-surface rocks into units and mapping their distribution and attitude.

  3. Stratigraphy, artefact industries and hominid associations for Sterkfontein, member 5.

    Kuman, K; Clarke, R J

    2000-06-01

    A revised stratigraphy for the early hominid site of Sterkfontein (Gauteng Province, South Africa) reveals a complex distribution of infills in the main excavation area between 2.8 and 1.4 m.y.a, as well as deposits dating to the mid to late Pleistocene. New research now shows that the Member 4 australopithecine breccia (2.8-2.6 Ma) extends further west than was previously thought, while a late phase of Member 4 is recognized in a southern area. The artefact-bearing breccias were defined sedimentologically as Member 5, but one supposed part of these younger breccias, the StW 53 infill, lacks in situ stone tools, although it does appear to post-date 2.6 Ma when artefacts first appear in the archaeological record. The StW 53 hominid, previously referred to Homo habilis, is here argued to be Australopithecus. The first artefact-bearing breccia of Member 5 is the Oldowan Infill, estimated at 2-1.7 Ma. It occupies a restricted distribution in Member 5 east and contains an expedient, flake-based tool industry associated with a few fossils of Paranthropos robustus. An enlarged cave opening subsequently admitted one or more Early Acheulean infills associated in Member 5 west with Homo ergaster. The artefacts attest to a larger site accumulation between ca. 1.7 and 1.4 Ma, with more intensive use of quartzite over quartz and a subtle but important shift to large flakes and heavier-duty tools. The available information on palaeoenvironments is summarized, showing an overall change from tropical to sub-tropical gallery forest, forest fringe and woodland conditions in Member 4 to more open woodland and grassland habitats in the later units, but with suggestions of a wet localized topography in the Paranthropus -bearing Oldowan Infill. PMID:10835264

  4. TAPHONOMIC ANALYSIS OF THE LATE EARLY PLEISTOCENE BONE REMAINS FROM BUIA (DANDIERO BASIN, DANAKIL DEPRESSION, ERITREA:EVIDENCE FOR LARGE MAMMAL AND REPTILE BUTCHERING

    IVANA FIORE

    2004-12-01

    Full Text Available The Early Pleistocene sedimentary succession of the Dandiero (Buia Basin (Danakil Depression, Eritrea has preserved a rich paleontological, paleoanthropological, and archeological record circa one million years old. Fieldwork undertaken between 1995 and 2003 led to the collection of fossil vertebrate remains now stored at the National Museum of Eritrea. Bones were recovered in different localities of the Dandiero Basin, where abundant archaeological and paleontological remains outcrop from the eroded sediments. The faunal collection of 436 animal bones from the Buia Basin, mostly derived from Uadi Aalad area, have undergone taphonomic analysis. Even though bone surfaces are poorly preserved due to abrasion, our work demonstrates carcass exploitation. Some specimens, mostly representing Hippopotamus gorgops and medium- to large-sized bovids, show traces of butchering left by stone tools. We also document, as far as we know for the first time, a single case of butchering involving a femur of a crocodile.   

  5. Stratigraphy of the Harwell boreholes

    Seven boreholes, five of them partially cored, were drilled at the Atomic Energy Research Establishment at Harwell as part of a general investigation to assess the feasibility of storing low- and intermediate-level radioactive waste in underground cavities. Two of the deeper boreholes were almost wholly cored to provide samples for hydrogeological, hydrochemical, mineralogical, geochemical, geotechnical, sedimentological and stratigraphical studies to enable variations in lithology and rock properties to be assessed, both vertically and laterally, and related to their regional geological setting. This report describes the lithologies, main faunal elements and stratigraphy of the Cretaceous, Jurassic, Triassic and Carboniferous sequences proved in the boreholes. More detailed stratigraphical accounts of the late Jurassic and Cretaceous sequences will be prepared when current studies of the faunal assemblages are complete. (author)

  6. Pollen analyses of Pleistocene hyaena coprolites from Montenegro and Serbia

    Argant Jacqueline

    2007-01-01

    Full Text Available The results of pollen analyses of hyaena coprolites from the Early Pleistocene cave of Trlica in northern Montenegro and the Late Pleistocene cave of Baranica in southeast Serbia are described. The Early Pleistocene Pachycrocuta brevirostris, and the Late Pleistocene Crocuta spelaea are coprolite-producing species. Although the pollen concentration was rather low, the presented analyses add considerably to the much-needed knowledge of the vegetation of the central Balkans during the Pleistocene. Pollen extracted from a coprolite from the Baranica cave indicates an open landscape with the presence of steppe taxa, which is in accordance with the recorded conditions and faunal remains. Pollen analysis of the Early Pleistocene samples from Trlica indicate fresh and temperate humid climatic conditions, as well as the co-existence of several biotopes which formed a mosaic landscape in the vicinity of the cave.

  7. 广西平乐鸡母岩发现的晚更新世人类牙齿化石%LATE PLEISTOCENE HOMININ TEETH FROM THE JIMUYAN CAVE,PINGLE COUNTY, GUANGXI,SOUTH CHINA

    王頠; 黄超林; 谢绍文; 鄢成林

    2011-01-01

    Five hominin teeth are recently discovered at the Jimuyan Cave in Pingle County, Southern China. The Jimuyan Cave is located at Juntang Village(24° 29' 52. 8" N,110° 50' 0. 79" E) ,20km southeast to the Pingle Town,with 163. 2m above the sea level. Mammalian fauna of the cave consists of eleven species,including: Macaca sp. ,Pongo pygmaeus weidenreichi, Hystrix cf. Subcristata, Ursus thibetanus ,Ahuropoda melanoleuca baconi ,Stegodon orhentalis, Tapirus sinensis,Sus scrofa,Muntiacus sp.,Cervus sp. And Bovidae gen. Et sp. Indet. This faunal assemblage contains four genera that are either extinct or no longer present in this region, including Stegodon, Tapirus, Ailuropoda and Pongo, which is distinctly different from that of Holocene, however similar to that of Late Pleistocene in Southern China. Thus, age of this fauna is dated to Late Pleistocene by biostratigraphy comparison. The hominin teeth in Jimuyan Cave are morphologically different from those of already known Homo erectus and Early Homo sapiens, nevertheless, similar to those of Late Homo sapiens in South China. This finding presents significant fossil evidence for the study of modern hunan origin and evolution in East Asia.The origin of modern humans is a controversial scientific topic at present. Based on fossil evidence of Homo sapiens in Africa are more ancient than that in Eastern Asia. With the results of molecular biology analysis, most of the anthropologists and geneticists support the hypothesis of modern humans originated in Africa. So far,the oldest fossils come from Omo-Kibish and Herto in Ethiopia, with the age of 160ka and 190ka respectively. The characteristics of these fossil skulls are intervenient between Homo sapiens and Homo heidelbergensis. Some of the hominin fossils,dated to 74 ~ 134ka,have been discovered at Klasies estuary in South Africa, but it is difficult to confirm whether these materials belong to modern human. Fossil hominin unearthed at Qafzeh and Skhul in Israel, Middle

  8. Cogenetic late Pleistocene rhyolite and cumulate diorites from Augustine Volcano revealed by SIMS 238U-230Th dating of zircon, and implications for silicic magma generation by extraction from mush

    Coombs, Michelle L.; Vazquez, Jorge A.

    2014-12-01

    Volcano, a frequently active andesitic island stratocone, erupted a late Pleistocene rhyolite pumice fall that is temporally linked through zircon geochronology to cumulate dioritic blocks brought to the surface in Augustine's 2006 eruption. Zircon from the rhyolite yield a 238U-230Th age of ˜25 ka for their unpolished rims, and their interiors yield a bimodal age populations at ˜26 ka and a minority at ˜41 ka. Zircon from dioritic blocks, ripped from Augustine's shallow magmatic plumbing system and ejected during the 2006 eruption, have interiors defining a ˜26 ka age population that is indistinguishable from that for the rhyolite; unpolished rims on the dioritic zircon are dominantly younger (≤12 ka) indicating subsequent crystallization. Zircon from rhyolite and diorite overlap in U, Hf, Ti, and REE concentrations although diorites also contain a second population of high-U, high temperature grains. Andesites that brought dioritic blocks to the surface in 2006 contain zircon with young (≤9 ka) rims and a scattering of older ages, but few zircon that crystallized during the 26 ka interval. Both the Pleistocene-age rhyolite and the 2006 dioritic inclusions plot along a whole-rock compositional trend distinct from mid-Holocene-present andesites and dacites, and the diorites, rhyolite, and two early Holocene dacites define linear unmixing trends often oblique to the main andesite array and consistent with melt (rhyolite) extraction from a mush (dacites), leaving behind a cumulate amphibole-bearing residue (diorites). Rare zircon antecrysts up to ˜300 ka from all rock types indicate that a Quaternary center has been present longer than preserved surficial deposits.

  9. The stratigraphy of Mars

    Tanaka, Kenneth L.

    1986-01-01

    A global stratigraphy of Mars was developed from a global geologic map series derived from Viking images; the stratigraphy is composed of three maps. A new chronostratigraphic classification system which consists of lower, middle, and upper Noachian, Hesperian, and Amazonian systems is described. The crater-density boundaries of the chronostratigraphic units and the absolute ages of the Martian epochs aer estimated. The relative ages of major geologic units and featues are calculated and analyzed. The geologic history of Mars is summarized on the maps in terms of epochs.

  10. HISTORICAL GEOLOGY & STRATIGRAPHY

    2011-01-01

    <正>20111095 Chen Rong(Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China);Li Yong Sequence Stratigraphy of Neogene in the Northern Slope of the Chengning Uplift(Journal of Stratigraphy,ISSN0253-4959,CN32-1187/P,34(2),2010,p.179-186,7 illus.,1 table,9 refs.)Key words:Neogene Period,stratigraphic framework,Huanghua Depression According to the tectonic evolutionary history and stratigraphic and depositional characteristics,and based on drill cores,cutting logs,well logs and high-resolution 3-D seismic data,sequences

  11. An Enduring Shell Artefact Tradition from Timor-Leste: Oliva Bead Production from the Pleistocene to Late Holocene at Jerimalai, Lene Hara, and Matja Kuru 1 and 2.

    Langley, Michelle C; O'Connor, Sue

    2016-01-01

    In this paper, we describe 485 Oliva spp. shell beads recovered from four archaeological cave sites Jerimalai, Lene Hara, Matja Kuru 1, and Matja Kuru 2, located in Timor-Leste, Island Southeast Asia. While Pleistocene-aged examples of modified marine shells used for personal ornamentation are common in African and Eurasian assemblages, they are exceedingly rare in Southeast Asia, leading some researchers to suggest that these Modern Human societies were less complex than those found further west. In Timor-Leste, the lowest Oliva bead to be recovered was directly dated to ca. 37,000 cal. BP, making it the oldest piece of personal ornamentation in Southeast Asia. Morphometric, taphonomic, use wear, and residue analyses of these beads alongside modern reference specimens, and experimentally made examples indicate that the Oliva shells were modified to be strung consecutively (as in a necklace), and while their mode of production changed remarkably little over the thousands of years they were utilised, an increase in their deposition around 6,000 cal. BP suggests that there was a change in their use coinciding with sea-level stabilisation. These tiny beads demonstrate that early Island Southeast Asian societies produced the same kinds of symbolic material culture we have come to expect from the more intensively studied African/Eurasian region, and that limited sampling and poor recovery methods have biased our perspectives of this region. PMID:27537696

  12. Dark humic alluvial paleosols in Central and Southern Mexico: Micromorphological indicators of Late Pleistocene megafauna habitats Paleosuelos aluviales con humus oscuro en el Centro y Sur de México: indicadores micromorfológicos de los hábitats de la megafauna del Pleistoceno tardío Paleosolos aluviais com húmus escuro no Centro e Sul do México: indicadores micromorfológicos dos habitats da megafauna do Pleistocénico tardio

    Rosa E. Tovar; Sergey Sedov; Berenice Solís; Elizabeth Solleiro

    2013-01-01

    During the Late Pleistocene, Mexico had a richer fauna than today with many different forms of megafauna that are now extinct. However, the ecosystems they inhabited and the particular ecological niches that they occupied are still poorly understood. Most of the findings of Pleistocene megafauna have been in alluvial deposits that present rich opportunities for paleoecological studies using paleopedological records. Floodplain paleosols commonly are poorly developed. However, micromorphologic...

  13. Calibration of amino acid racemization (AAR) kinetics in United States mid-Atlantic Coastal Plain Quaternary mollusks using 87Sr/ 86Sr analyses: Evaluation of kinetic models and estimation of regional Late Pleistocene temperature history

    Wehmiller, J. F.; Harris, W.B.; Boutin, B.S.; Farrell, K.M.

    2012-01-01

    The use of amino acid racemization (AAR) for estimating ages of Quaternary fossils usually requires a combination of kinetic and effective temperature modeling or independent age calibration of analyzed samples. Because of limited availability of calibration samples, age estimates are often based on model extrapolations from single calibration points over wide ranges of D/L values. Here we present paired AAR and 87Sr/ 86Sr results for Pleistocene mollusks from the North Carolina Coastal Plain, USA. 87Sr/ 86Sr age estimates, derived from the lookup table of McArthur et al. [McArthur, J.M., Howarth, R.J., Bailey, T.R., 2001. Strontium isotopic stratigraphy: LOWESS version 3: best fit to the marine Sr-isotopic curve for 0-509 Ma and accompanying Look-up table for deriving numerical age. Journal of Geology 109, 155-169], provide independent age calibration over the full range of amino acid D/L values, thereby allowing comparisons of alternative kinetic models for seven amino acids. The often-used parabolic kinetic model is found to be insufficient to explain the pattern of racemization, although the kinetic pathways for valine racemization and isoleucine epimerization can be closely approximated with this function. Logarithmic and power law regressions more accurately represent the racemization pathways for all amino acids. The reliability of a non-linear model for leucine racemization, developed and refined over the past 20 years, is confirmed by the 87Sr/ 86Sr age results. This age model indicates that the subsurface record (up to 80m thick) of the North Carolina Coastal Plain spans the entire Quaternary, back to ???2.5Ma. The calibrated kinetics derived from this age model yield an estimate of the effective temperature for the study region of 11??2??C., from which we estimate full glacial (Last Glacial Maximum - LGM) temperatures for the region on the order of 7-10??C cooler than present. These temperatures compare favorably with independent paleoclimate information

  14. Reply to: 'A late Pleistocene clockwise rotation phase of Zakynthos (Greece) and implications for the evolution of the western Aegean Arc'

    Duermeijer, C.E.; Langereis, C.G.

    2002-01-01

    During the 80s, a number of seminal papers were published by the Gif-sur-Yvette group of Carlo Laj and co-workers, on the late Neogene palaeomagnetic rotations of the Aegean and, in particular, of the Aegean Arc system. These studies shed new light on the tectonic evolution of the region (e.g. [1,2

  15. Mineralogical Stratigraphy of Ganges Chasma, Mars

    Cull-Hearth, Selby; Clark, M. Caroline

    2015-11-01

    Mars’ Valles Marineris canyon system reveals a several-kilometer deep stratigraphies sequence that extends thousands of kilometers; this sequence thus represents a unique opportunity to explore millions of years of volcanic and aqueous activity in this region of Mars. Of particular interest to the study of both volcanic and aqueous processes is Ganges Chasma, which lies on the northeastern boundary of the Valles Marineris canyon system on Mars. The canyon likely opened during the Late Noachian to Early Hesperian, modifying previously emplaced Noachian-aged volcanic plains. During formation, volcanic activity from the nearby Tharsis shield complex emplaced olivine-rich dikes throughout the region. After formation, sulfate-bearing Interior Layered Deposits (ILDs) were emplaced in Ganges and many other chasmata throughout the Valles Marineris system. Today, Ganges reveals a complex stratigraphy, including wide-spread olivine-rich sands, hydrated minerals on the plateaus surrounding the canyon, and a central sulfate-rich ILD. Here, we present updated stratigraphies of Ganges Chasma, using new data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), and synthesizing it with previous data sets. Olivine sands are traced back to source outcrops on the canyon floor, and new outcrops of hydrated minerals on the surrounding plateau are identified and mapped. Recently reported spectroscopic signatures of ankerite and smectite in the chasm are assessed, and new olivine-rich outcrops identified and mapped. Understanding the stratigraphy of Ganges Chasma will help us compare stratigraphies among the chasmata of the Valles Marineris, further building our understanding of the geologic history of this large region of Mars.

  16. A new record of Equus (Mammalia: Equidae from the Late Pleistocene of central-south Chile Un nuevo registro de Equus (Mammalia: Equidae para el Pleistoceno Superior de Osorno, Chile

    OMAR P RECABARREN

    2011-12-01

    Full Text Available Fourteen dental and bone parts of a horse excavated from the Pilauco paleontological site, Osorno (40°39' S-73°07' W are analysed and interpreted. This site was formed in association with a peat bog located on the banks of the old Damas River and has conserved abundant late Pleistocene mammalian fauna and flora materials. A date of 11457 ± 140 14C yrs B.P. was obtained from a molar and agrees with our stratigraphic age model. We have identified the fossils as pertaining to the species Equus (Amerhippus andium, which confirms its presence in central-south Chile. Furthermore, the recorded geographic location indicate that the metapodial adaptations of the specimens previously described agree with the reconstructed late Pleistocene landscape of Pilauco, dominated by soft volcanic soils and isolated forest patches over large extensions of grasslands.Se analizan e interpretan 14 fósiles correspondientes a dientes y huesos de caballo registrados en el sitio Pilauco, Osorno (40°39' S-73°07' W. El sitio se formó asociado a un pantano en un borde del antiguo río Damas; en él se ha conservado abundante material de mastofauna y flora pleistocénica. Una fecha radiocarbónica de 11457 ± 140 A.P obtenida de un molar, es concordante con el modelo de edad del sitio. La identificación taxonómica permite asociar a los fósiles a la especie Equus (Amerhippus andium, lo que confirma la presencia de la especie en el centro-sur de Chile. Por otra parte, la posición geográfica de los hallazgos y la reconstrucción del paisaje indicarían que se trata de ejemplares cuyas adaptaciones en los metapodios son concordantes para el paisaje pleistocénico de Pilauco dominado por suelos volcánicos blandos, con presencia de bosquetes dispersos en grandes extensiones de praderas de gramíneas.

  17. Human burial evidence from Hattab II Cave and the question of continuity in Late Pleistocene-Holocene mortuary practices in Northwest Africa

    Barton, N.; Bouzouggar, A; Humphrey, L.; Berridge, P.; Collcutt, S; Gale, R; Parfitt, S.; Parker, A; Rhodes, E; Schwenninger, J.L.

    2008-01-01

    Archaeological excavations in 2002-3 at Hattab H Cave in northwestern Morocco revealed all undisturbed Late Palaeolithic Iberomaurusian human burial. This is the first Iberomaurusian inhumation discovered in the region. The skeleton is probably that Of a male aged between 25 and 30 years. The individual shows a characteristic absence of the central upper incisors reported in other Iberomaurusian burials. Accompanying the burial are a stone core and a number of grave goods including bone point...

  18. Tephrochronology of the Mont-Dore volcanic Massif (Massif Central, France): new 40Ar/39Ar constraints on the Late Pliocene and Early Pleistocene activity

    Nomade, Sébastien; Pastre, Jean-François; Nehlig, Pierre; Guillou, Hervé; Scao, Vincent; Scaillet, Stéphane

    2014-03-01

    The Mont-Dore Massif (500 km2), the youngest stratovolcano of the French Massif Central, consists of two volcanic edifices: the Guéry and the Sancy. To improve our knowledge of the oldest explosive stages of the Mont-Dore Massif, we studied 40Ar/39Ar-dated (through single-grain laser and step-heating experiments) 11 pyroclastic units from the Guéry stratovolcano. We demonstrate that the explosive history of the Guéry can be divided into four cycles of explosive eruption activity between 3.09 and 1.46 Ma (G.I to G.IV). We have also ascertained that deposits associated with the 3.1-3.0-Ma rhyolitic activity, which includes the 5-km3 "Grande Nappe" ignimbrite, are not recorded in the central part of the Mont-Dore Massif. All the pyroclastites found in the left bank of the Dordogne River belong to a later explosive phase (2.86-2.58 Ma, G.II) and were channelled down into valleys or topographic lows where they are currently nested. This later activity also gave rise to most of the volcanic products in the Perrier Plateau (30 km east of the Mont-Dore Massif); three quarters of the volcano-sedimentary sequence (up to 100 m thick) was emplaced within less than 20 ky, associated with several flank collapses in the northeastern part of the Guéry. The age of the "Fournet flora" (2.69 ± 0.01 Ma) found within an ash bed belonging to G.II suggests that temperate forests already existed in the French Massif Central before the Pliocene/Pleistocene boundary. The Guéry's third explosive eruption activity cycle (G.III) lasted between 2.36 and 1.91 Ma. It encompassed the Guéry Lake and Morangie pumice and ash deposits, as well as seven other important events recorded as centimetric ash beds some 60 to 100 km southeast of the Massif in the Velay region. We propose a general tephrochronology for the Mont-Dore stratovolcano covering the last 3.1 My. This chronology is based on 44 40Ar/39Ar-dated events belonging to eight explosive eruption cycles each lasting between 100 and 200

  19. Fluvial system response to late Pleistocene-Holocene sea-level change on Santa Rosa Island, Channel Islands National Park, California

    Schumann, R. Randall; Pigati, Jeffrey S.; McGeehin, John P.

    2016-09-01

    Santa Rosa Island (SRI) is one of four east-west aligned islands forming the northern Channel Islands chain, and one of the five islands in Channel Islands National Park, California, USA. The island setting provides an unparalleled environment in which to record the response of fluvial systems to major changes of sea level. Many of the larger streams on the island occupy broad valleys that have been filled with alluvium and later incised to form steep- to vertical-walled arroyos, leaving a relict floodplain as much as 12-14 m above the present channel. The period of falling sea level between the end of the last interglacial highstand at ~ 80 ka and the last glacial lowstand at ~ 21 ka was marked by erosion and incision in the uplands and by deposition of alluvial sediment on the exposed marine shelf. Sea level rose relatively rapidly following the last glacial lowstand of - 106 m, triggering a shift from an erosional to a depositional sedimentary regime. Accumulation of sediment occurred first through vertical and lateral accretion in broad, shallow channels on the shelf. Channel avulsion and delta sedimentation produced widespread deposition, creating lobes or wedges of sediment distributed across relatively large areas of the shelf during the latest Pleistocene. Backfilling of valleys onshore (landward of present sea level) appears to have progressed in a more orderly and predictable fashion throughout the Holocene primarily because the streams were confined to their valleys. Vertical aggradation locally reduced stream gradients, causing frequent overbank flooding and lateral channel shift by meandering and/or avulsion. Local channel gradient and morphology, short-term climate variations, and intrinsic controls also affected the timing and magnitudes of these cut, fill, and flood events, and are reflected in the thickness and spacing of the episodic alluvial sequences. Floodplain aggradation within the valleys continued until at least 500 years ago, followed by

  20. LATE QUATERNARY SEISMIC SEQUENCES AND SEDIMENTATION ALONG THE COAST OFF TAISHAN,GUANGDONG,AS REVEALED BY HIGH RESOLUTION SEISMIC DATA

    吴时国; 黄孝健

    2002-01-01

    Seismic stratigraphic analysis of 150 km of high-resolution seismic profiles (G E OPULSE and 3.5 kHz) obtained along the muddy coast off Taishan, Guangdong pr ovided valuable information on the offshore Quaternary stratigraphy, tectonics, sedimentary evol ution, and environmental and engineering geology of this area.The following late Quaternary stratigraphic sequences were mapped. (1) Pleistoce ne alluvial silty sand and shallow marine clay; (2) coarse fluvial channel sand; (3 ) nearshore and bay clayey sediments. The incision of fluvial channels occurred in two stages: duri ng the Late Pleistocene and at the beginning of the Holocene. The Pleistocene fluvial channe ls have been filled by coarse sand overlain by more than 10 m of late Pleistocene clay and 20-30 m o f Holocene clay.The coastal area is dissected by two major fault systems: the first group strike s ENE-WSW and controls the evolution of the adjacent Quaternary basin, while the second one tr ends NNE-SSW. These fault systems must be taken into account in any coastal engineering consid erations. In addition, both granitic and metamorphic basements were recognized.

  1. Development of the alluvial and lacustrine terraces on the northern margin of the Hetao Basin, Inner Mongolia, China: Implications for the evolution of the Yellow River in the Hetao area since the late Pleistocene

    Jia, Liyun; Zhang, Xujiao; Ye, Peisheng; Zhao, Xitao; He, Zexin; He, Xiangli; Zhou, Qingshuo; Li, Jie; Ye, Mengni; Wang, Zhen; Meng, Jing

    2016-06-01

    Terrace formation processes can reflect the evolution of large rivers. The Hetao Basin is a floodplain of the Yellow River, and there are two to three terraces that extend E-W on the northern margin. Based on a detailed field geological survey and measurement of the terrace sections, combined with sedimentological and chronological analyses, we reconstructed the developmental processes of the three terraces and inferred that three river terraces were formed by the Yellow River. The OSL dating results show that the time of deposition of terrace 3 was prior to 118 ka BP. Subsequently, the terrace began to experience incision and formed the geomorphic surface of terrace T3. Similarly, terrace 2 and terrace 1 were mainly deposited from ~ 109 and 59 ka, respectively; and began to be incised prior to 71 and 46 ka, respectively. The three terraces in the northern Hetao Basin are the products of the combined actions of climatic shifts and tectonic uplift. The Yellow River's evolutionary history in the Hetao area since the Late Pleistocene is discussed. Before about 120 ka BP, the Yellow River may have flowed through the northern Hetao Basin. Between 110 and 70 ka BP, the Yellow River experienced at least two changes between river and lake sedimentation. From 60 to 50 ka, a very large river-connected lake of the Yellow River was developed in the Hetao Basin. After 50 ka, the Hetao river-connected paleolake of the Yellow River gradually dried.

  2. Vegetation and climate changes during the late Pliocene and early Pleistocene in SW Turkey - Comment to the published paper by Jiménez-Moreno et al., Quaternary Research, 84 (2015), 448-456

    Elitez, İrem; Yaltırak, Cenk; Şahin, Murat

    2016-05-01

    There are several Miocene to recent terrestrial and lacustrine basins along the NE-SW-trending Burdur-Fethiye Shear Zone in southwestern Turkey (Elitez and Yaltırak, 2014; Hall et al., 2014; Elitez et al., 2015). The stratigraphic positions of the sequences in these basins are controversial (e.g., Alçiçek, 2015; Elitez et al., 2015). Jiménez-Moreno et al. (2015) interpreted the late Pliocene-early Pleistocene climate based on the vegetation changes at the Ericek and Bıçakçı localities south of the Çameli town. Our observations at these localities (e.g., Elitez et al., 2015) revealed that there are three important geological problems with Jiménez-Moreno et al. (2015): (1) the geographic locations of the samples used in this manuscript are inacurate, (2) the lithologies and the associated thicknesses of the sequences reported in the manuscript are inconsistent, and (3) the positions of the fossils and pollens in an allocthonous stratigraphic succession has no stratigraphic control. The primary aim of this comment is to correctly identify the precise positions of the fossil and pollen data in the stratigraphic sequence rather than an objection to the interpretation of the vegetation and climate data in southwestern Turkey.

  3. Dating Lake Tahoe (CA/NV) and Mono Lake (CA) sediment using palaeomagnetic secular variation as a chronology for late Pleistocene palaeoclimate in the U.S. Great Basin

    Liddicoat, Joseph

    2010-05-01

    In 1976, six meters of graded and varved sediment were recovered in three piston cores from Lake Tahoe, CA/NV, and used for palaeomagnetic and sedimentologic investigations (Palmer et al., 1979; Denham, 1981). The long-term changes (secular variation) in the Lake Tahoe palaeomagnetic record were compared to secular variation in exposed lacustrine sediment of the Wilson Creek Formation (Lajoie, 1993) in the Mono Basin, CA, (Denham and Cox, 1971), 100 km away. During the more than 30 years since the coring was done in Lake Tahoe, the record of palaeomagnetic secular variation in the Mono Basin and elsewhere in the Great Basin has been refined (Liddicoat and Coe, 1979; Lund et al., 1988, Liddicoat and Coe, 1997; Liddicoat and Coe, 1998; Benson et al., 1998; Negrini and Davis, 1992; Kent et al., 2002; Zimmerman et al., 2006) to allow a reexamination of the palaeomagnetic directions and environmental magnetic record in the Lake Tahoe cores and the age of those sediments. Inferences are also possible about the sedimentological importance during the recording of the palaeomagnetic field at Lake Tahoe and possibly in the Mono Basin, and the age of the Lake Tahoe sediment recovered, which postdates the Mono Lake Excursion. The age of the Mono Lake Excursion and Wilson Creek Formation is relevant to investigations of Late Pleistocene palaeoclimate reconstructions for the U.S. Great Basin (Zimmerman et al., 2006).

  4. Geochemistry and Genesis of the Pampean and Post-Pampean Formations (Late Pleistocene-Holocene), Central and Northern Argentina Pampas and Its Adjacent Region-An Approaching Case Study

    Roberto Torra

    2004-01-01

    Littoral siliciclastic shallow marine horizontal conformable beds (a heterolithic succession), Middle to Late Miocene, outcropping in northeastern Argentina (Ituzaingó Formation) and overlying transitional conformable horizontal regolithic mantle-rock bed derived from them (the Pampean and Post-Pampean Formations), were geochemically analyzed. The focus of this study is placed on the application of geochemical parameter and signature analyses related with the aforementioned geological units, which are of subcontinental extension into South America. The encountered results show an outstandingly similar geochemical behaviour between them. The main conclusion is that regolithic mantle-rock beds were derived from the littoral shallow marine mudstone (silty-argillaceous) beds. This is in oposition to previous aeolian processes proposed early in the 50's and later. These mudstone beds constitute important sections of the littoral shallow marine sequence beds (outcropping HST parasequence). Such regolitization proposed for the Pampean and Post-Pampean Formations predominantly developed in-situ during the Late Pleistocene and Holocene. The main erosional and mobilized agents were the surface free water (pluvial, fluvial and laminar water sheets) and vadose water. So, the wind flows and/or the immense air flow hurricanes are of insignificant sedimentological influence. Otherwise, there is not a proved appropiate sandy-silty reservoir for a reasonable support of the "aeolian hypothesis", as well as clear aeolian structures settled in the regolithic mantle-rock bed. In spite of these lines of equality textural-structural evidence, the geochemical values for both major elements and trace elements, demonstrate that the Miocene heterolithic marine succession was the mother rock of the overlying regolithic mantle-rock bed, which was formed as an in-situ mantle-rock bed.

  5. Paleoceanographic interpretations of late Pleistocene to Holocene sedimentological and geochemical proxy-data from SE-Atlantic abyssal plains (Cape, Angola and Guinea Basin)

    Piller, W. E.; Müllegger, S.

    2009-04-01

    Sediments of the deep abyssal regions of the Southeast Atlantic (Cape Basin, Angola Basin and Guinea Basin) were studied to reconstruct changes in surface and deep water circulation, bioproductivity, and terrigenous sediment flux. To gain these results various sedimentological and geochemical proxies were imposed, including grain size data, foraminiferal fragmentation, carbonate and organic carbon content, as well as stable oxygen and carbon isotope contents of foraminiferal tests. Samples were gained with a multicorer device during Meteor cruise 63/2 (2005) in water depths between ~5,100 and ~5,600 m. The superficial 30 cm of sediment, sampled in 1/2, 1 and 5 cm steps, were processed for this study. The record covers parts of the Pleistocene and Holocene. Even if the sedimentation conditions seem to be similar in the deep-sea regions of the SE-Atlantic there are clear differences between the three sampled locations. This is caused by major changes in deep water corrosiveness leading to fluctuations in the sedimentation rate and carbonate preservation. Cape Basin localities show a pattern of enhanced carbonate preservation around 12 ka BP possibly indicating a delayed Last Glacial Maximum signal. This pattern, which is typical for Indo-Pacific records, clearly points to an influence of Antarctic Bottom Water (AABW) at water depths below 5000 m in the Northern Cape Basin. The non-correlation between carbonate content and grain size distribution is owing to a coccoliths' dominated carbonate production possibly caused by low nutrient availability in surface waters and the higher dissolution susceptibility of foraminiferal tests. Angola Basin samples delivered highest sand contents, a carbonate peak and low organic carbon values around 8.2 ka BP which indicate a reduced bioproduction and nutrient supply in superficial waters. A connection of the 8.2 ka cold event in the northern hemisphere and central African precipitation, equatorial East Atlantic (EEA) upwelling

  6. Possible Late Pleistocene volcanic activity on Nightingale Island, South Atlantic Ocean, based on geoelectrical resistivity measurements, sediment corings and (14)C dating

    Bjørk, Anders Anker; Björck, Svante; Cronholm, Anders;

    2011-01-01

    Tristan da Cunha is a volcanic island group situated in the central South Atlantic. The oldest of these islands, Nightingale Island, has an age of about 18Ma. In the interior of the island, there are several wetlands situated in topographic depressions. The ages of these basins have been unknown...... method. The irregular shapes of the basins and the lack of clear erosional features indicate that they are not eruption craters and were not formed by erosion. Instead, we regard them as morphological depressions formed between ridges of trachytic lava flows and domes at a late stage of the formation of...... the volcanic edifice. The onset of sedimentation within these basins appears to have occurred between 24 and 37 ka with the highest situated wetland yielding the highest ages. These ages are very young compared to the timing of the main phase of the formation of the island, implying volcanic activity...

  7. Oxygen and silicon stable isotopes of diatom silica. Reconstructing changes in surface water hydrography and silicic acid utilization in the late Pleistocene subarctic Pacific

    Deglacial variations in upper ocean nutrient dynamics and stratification in high latitudes, as well as associated changes in thermohaline overturning circulation, are thought to have played a key role in changing atmospheric CO2 concentrations. This thesis examines the relationship between past changes in subarctic Pacific upper ocean stratification and nutrient (silicic acid) utilization, using oxygen and silicon stable isotopes of diatom silica, for the first time at millennial-scale resolution and analyzed with a new and efficient instrumentation set-up. The isotopic data, presented in three manuscripts, show a consistent picture of millennial-scale variability in upper ocean stratification and silicic acid utilization during the last ∝50 ka BP, e.g. indicating that the subarctic Pacific was a source region for atmospheric CO2 during the last deglaciation (late Heinrich Stadial 1 and the Boelling/Alleroed). The presented results demonstrate the high potential of combined diatom oxygen and silicon stable isotope analysis especially for, but not restricted to, marine regions characterized by a low biogenic carbonate content like the subarctic Pacific and the Southern Ocean.

  8. Tectonic control on the stratigraphic framework of Late Pleistocene and Holocene deposits in Marajó Island, State of Pará, eastern Amazonia

    Dilce F. Rossetti

    2010-06-01

    Full Text Available The traditional view that the Brazilian Amazonia is located in a tectonically stable area since the Cretaceous is changing in front of the increasing documentation of fault reactivations even during the Holocene. How the sedimentary record has responded to these events is an issue that remains to be approached with basis on field data. This work focuses on the stratigraphic correlation of late Quaternary deposits from eastern Marajó Island, with the goal of demonstrating the role of fault reactivation on the origin and preservation of these deposits. Despite the location in a stable platform of a continental passive margin, three studied stratigraphic units display significant vertical offsets that define two depocenters that are better explained through tectonic displacements. This interpretation is reinforced by several morphostructural features related to faults that occur between the studied drills. Without the influence of tectonics, sediment preservation in this characteristically low-lying terrain would have been negligible. The results of the present work motivate to look for other tectonically-influenced areas in Amazonia, which similarly might have acted as sites for sediment accommodation during the late Quaternary. These sedimentary records have great potential to be the source of valuable information for reconstructing Quaternary geological events in Northern Brazil.A visão tradicional de que a Amazônia brasileira localiza-se em ma área tectonicamente estável desde o Cretáceo está mudando perante a crescente documentação de reativações de falha, até mesmo durante o Holoceno. Como o registro sedimentar respondeu a esses eventos é um tema que permanece por ser abordado com base em dados de campo. Este trabalho enfatiza a correlação estratigráfica de depósitos quaternários tardios no leste da Ilha do Marajó, com o objetivo de demonstrar a importância de reativações de falha na origem e preservação desses dep

  9. Exploring Globorotalia truncatulinoides coiling ratios as a proxy for subtropical gyre dynamics in the northwestern Atlantic Ocean during late Pleistocene Ice Ages

    Billups, K.; Hudson, C.; Kunz, H.; Rew, I.

    2016-05-01

    We explore the use of the coiling direction of planktic foraminifer Globorotalia truncatulinoides in sediment cores from the northwestern subtropical Atlantic Ocean as a proxy for variations in the intensity of the western boundary of the subtropical gyre over the past 280 kyr. Core-top sediments from the study region are dominated by the left coiling variety consistent with the deep permanent thermocline at the study sites (KNR140-37PC and Ocean Drilling Program Site 1059). Downcore G. truncatulinoides (sinistral) maxima occur in conjunction with 14 out of the 25 (Northern and Southern Hemisphere) precession maxima contained in the study interval. The agreement between the dominance of left coiling tests and the precession index of the Southern Hemisphere, in particular, supports a link between a deep thermocline in the northwestern subtropical Atlantic and northward flow of equatorially sourced warm surface currents, a situation analogous to the Late Holocene. Interglacial marine oxygen isotope stage (MIS) 5 lacks G. truncatulinoides (s) minima attesting to the relative stability of the western boundary during an interval of prolonged global warmth. G. truncatulinoides (s) disappear during the glacial extremes of MIS 2, 6, and 8 implying a weaker western boundary current at these times. Our results support that the coiling direction of this species is sensitive to variations in hydrography of the western boundary of the subtropical gyre. Because of the association between G. truncatulinoides (s) and precession maxima in both hemispheres, results support the importance of oceanic heat transport in half-precession climate variability in the North Atlantic.

  10. High-resolution shear-wave seismics across the Carlsberg Fault zone south of Copenhagen - Implications for linking Mesozoic and late Pleistocene structures

    Kammann, Janina; Hübscher, Christian; Boldreel, Lars Ole; Nielsen, Lars

    2016-07-01

    The Carlsberg Fault zone (CFZ) is a NNW-SSE striking structure close to the transition zone between the Danish Basin and the Baltic Shield. We examine the fault evolution by combining very-high-resolution onshore shear-wave seismic data, one conventional onshore seismic profile and marine reflection seismic profiles. The faulting geometry indicates a strong influence of Triassic subsidence and rifting in the Central European Basin System. Growth strata within the CFZ surrounding Höllviken Graben reveal syntectonic sedimentation in the Lower Triassic, indicating the opening to be a result of Triassic rifting. In the Upper Cretaceous growth faulting documents continued rifting. These findings contrast the Late Cretaceous to Paleogene inversion tectonics in neighboring structures, such as the Tornquist Zone. The high-resolution shear-wave seismic method was used to image faulting in Quaternary and Danian layers in the CFZ. The portable compact vibrator source ElViS III S8 was used to acquire a 1150 m long seismic section on the island Amager, south of Copenhagen. The shallow subsurface in the investigation area is dominated by Quaternary glacial till deposits in the upper 5-11 m and Danian limestone below. In the shear-wave profile, we imaged the uppermost 30 m of the western part of CFZ. The complex fault zone comprises normal block faults and one reverse block fault. The observed faults cut through the Danian as well as the Quaternary overburden. Hence, there are strong indicators for ongoing faulting, like mapped faulting in Quaternary sediments and ongoing subsidence of the eastern block of the CFZ as interpreted by other authors. The lack of earthquakes localized in the fault zone implies that either the frequency of occurring earthquakes is too small to be recorded in the observation time-span, or that the movement of the shallow sub-surface layers may be due to other sources than purely tectonic processes.

  11. Pleistocene horses (genus Equus in the central Balkans

    Forsten Ann

    2003-01-01

    Full Text Available A review of the fossil horses of the genus Equus from the central Balkans, a mountainous area comprising Serbia and Montenegro, is presented in this paper. The time period covered by the finds is from the late Early to and including the Late Pleistocene, but the record is not complete: the dated finds are Late Pleistocene in age, while Early and Middle Pleistocene are poorly represented. The horses found resemble those from neighbouring countries from the same time period, probably showing the importance of river valleys as migration routes. The Morava River valley runs in a roughly south-to-north direction, connecting, via the Danube and Tisa River valleys the Hungarian Pannonian Plain in the north with northern Greece in the south, via the Vardar River valley in Macedonia. In Pleistocene, large mammals, including horses, probably used this route for dispersal.

  12. Deep-sea pleistocene biostratigraphy.

    Lidz, L

    1966-12-16

    The first detailed paleontological analysis of a deep-sea pistoncore from the Caribbean Sea has been completed. The core, P6304-8, was raised from 3927 meters, east of Beata Ridge at 14 degrees 59'N, 69 degrees 20'W. Formerly, stratigraphic works in this area were based on studies of paleotemperature, measured by the oxygen isotope mass spectrometry method, or on micropaleontological analysis by means of rapid or cursory examinations. For core P6304-8, samples for foraminiferal analysis were taken at 10-centimeter intervals and split into smaller samples containing an average of 710 individuals (smallest sample, 517 individuals); all individuals were then identified and counted. By use of data derived from populations of this size, a statistical reliability was insured within a 5 percent limnit. Temperature oscillations, the best method of portraying Pleistocene stratigraphy, were shown by using ratios of the relative abundances of tropical and subtropical planktonic foraminifera to those found in temperate and cooler waters. These ratios correlate well with existing paleotemperature measurements for the same core, obtained by the oxygen isotope mass spectrometry method. PMID:17821563

  13. Hippidion saldiasi Roth, 1899 (Mammalia, Perissodactyla en el Pleistoceno tardío de Calama, norte de Chile Late Pleistocene Hippidion saldiasi Roth, 1899 (Mammalia, Perissodactyla from Calama, northern Chile

    MARÍA TERESA ALBERDI

    2007-06-01

    Full Text Available Se describen restos del género Hippidion procedentes de la zona del desierto de Atacama (Calama, Segunda Región de Chile. El conjunto analizado corresponde a un esqueleto bastante completo proveniente del yacimiento Betecsa 1, así como escasas unidades del yacimiento Kamac Mayu. En ambos sitios se identifica H. saldiasi. A partir de dos dataciones radiométricas por AMS del ejemplar estudiado, los restos se sitúan estratigráficamente en el Pleistoceno Superior (21.070 ± 100 AP y 21.380 ± 100 14C AP. Se infieren datos ambientales y de dieta a partir de análisis de isótopos estables en los restos de Hippidion saldiasi del sitio Betecsa 1 cuyo valor de δ13C en hueso fue de -15,45 y el valor en esmalte de dientes fue de -16,68, sugiriendo una alimentación con pastos C3. El cráneo recuperado es el primero conocido de esta especieThis paper describes the Hippidion bones recovered from the Atacama Desert (Calama, Second Region of Chile. The analyzed assemblage corresponds to a nearly complete skeleton from Betecsa 1 site and more poorly preserved remains from Kamac Mayu site. In both H. saldiasi is identified. Two 14C radiometric determinations indicate late Pleistocene age for these remains (21,070 ± 100 BP and 21,380 ± 100 BP. Environmental and diet inferences from stable isotope analysis are also presented. The δ13C value from Betecsa 1 horses (-15.45 from bone sample and -16.68 from enamel sample suggest a dietary adaptation exclusively C3 feeders. This is the first skull and associated skeleton recovered of this species

  14. Late Pleistocene Panthera leo spelaea (Goldfuss, 1810 skeletons from the Czech Republic (central Europe; their pathological cranial features and injuries resulting from intraspecific fights, conflicts with hyenas, and attacks on cave bears

    Diedrich C G

    2011-11-01

    Full Text Available The world’s first mounted "skeletons" of the Late Pleistocene Panthera leo spelaea (Goldfuss, 1810 from the Sloup Cave hyena and cave bear den in the Moravian Karst (Czech Republic, central Europe are compilations that have used bones from several different individuals. These skeletons are described and compared with the most complete known skeleton in Europe from a single individual, a lioness skeleton from the hyena den site at the Srbsko Chlum-Komín Cave in the Bohemian Karst (Czech Republic. Pathological features such as rib fractures and brain-case damage in these specimens, and also in other skulls from the Zoolithen Cave (Germany that were used for comparison, are indicative of intraspecific fights, fights with Ice Age spotted hyenas, and possibly also of fights with cave bears. In contrast, other skulls from the Perick and Zoolithen caves in Germany and the Urșilor Cave in Romania exhibit post mortem damage in the form of bites and fractures probably caused either by hyena scavenging or by lion cannibalism. In the Srbsko Chlum-Komín Cave a young and brain-damaged lioness appears to have died (or possibly been killed by hyenas within the hyena prey-storage den. In the cave bear dominated bone-rich Sloup and Zoolithen caves of central Europe it appears that lions may have actively hunted cave bears, mainly during their hibernation. Bears may have occasionally injured or even killed predating lions, but in contrast to hyenas, the bears were herbivorous and so did not feed on the lion carcasses. The articulated lion skeletons found in cave bear dens deep within caves scattered across Europe (such as those from the Sloup, Zoolithen and Urșilor caves can therefore now be explained as being the result of lions being killed during predation on cave bears, either by the cave bears defending themselves or as a result of interspecific fights.

  15. New evidence of the sabertooth cat Smilodon (Carnivora: Machairodontinae in the late Pleistocene of southern Chilean Patagonia Nueva evidencia del gato dientes de sable Smilodon (Carnivora: Machairodontinae en el Pleistoceno tardío de Patagonia meridional chilena

    ALFREDO PRIETO

    2010-06-01

    Full Text Available Southern Patagonia is rich in late Pleistocene mammals, especially herbivores such as Camelids, Equids and Xenarthrans. Carnivores, on the other hand, are not commonly found in the paleontological record. One genus, Smilodon, is of particular interest because its presence in the region has not been demonstrated. In this paper, we present new fossil dental evidence that supports the presence of Smilodon populator (Lund in the region. This evidence corresponds to the most southern record of the genus in the world, and the final step in the colonization of South America after the Great American Biotic Interchange. An AMS radiocarbon date on teeth indicates that the remains from Southern Chilean Patagonia are the most recent record for the genus in South America.Surpatagonia es particularmente rica en mamíferos finiplesitocenos, particularmente camélidos, équidos y xenartros. Los carnívoros, por su parte, se encuentran representados en menor número en el registro paleontológico. Dentro de estos, el género Smilodon, es de particular interés debido a que su presencia en la región no ha sido convincentemente demostrada. En este trabajo presentamos evidencia dental que permite confirmar la presencia de Smilodon populator (Lund en la región. Esta evidencia corresponde al registro más sureño de este taxón y al paso final en la colonización de América del Sur después del Gran Intercambio Biótico Americano. Un fechado radiocarbónico directo AMS indica que los restos de Patagonia del Sur corresponden a los registros más tardíos para este género en el subcontinente.

  16. Quaternary stratigraphy: Recent changes

    Gaudenji Tivadar

    2012-01-01

    Full Text Available Corrections to the Quaternary stratigraphic division of Serbia was updated/renewed by lowering limit of the Pleistocene / Quaternary to the beginning of the Gelasian that is at approximately 2.588 million years. Rather than the officially rejected Penck & Brückner Alpine stratigraphic model, the use of oxygen isotope stages (OIS / MIS is recommended. Climatostratigraphic terms glacial and interglacial have a regional applicability and their use is recommended only in areas where there are traces of glaciation, while the terms cold and warm stage (or moderate stages should be used within the global context. Eopleistocene is a regional term for the former Soviet Union and due to its uniqueness it can hardly be applied in the stratigraphical scheme of the Quaternary depostis in Serbia. With the latest extension of the Lower Pleistocene, further use of Eopleistocene would lead to further confusion in stratigraphic correlation as such the use of the Lower / Early Pleistocene or other appropriate stratigraphic units is recommended. [Projekat Ministarstva nauke Republike Srbije, br. 47007

  17. The orbital record in stratigraphy

    Fischer, Alfred G.

    1992-01-01

    Orbital signals are being discovered in pre-Pleistocene sediments. Due to their hierarchical nature these cycle patterns are complex, and the imprecision of geochronology generally makes the assignment of stratigraphic cycles to specific orbital cycles uncertain, but in sequences such as the limnic Newark Group under study by Olsen and pelagic Cretaceous sequence worked on by our Italo-American group the relative frequencies yield a definitive match to the Milankovitch hierarchy. Due to the multiple ways in which climate impinges on depositional systems, the orbital signals are recorded in a multiplicity of parameters, and affect different sedimentary facies in different ways. In platform carbonates, for example, the chief effect is via sea-level variations (possibly tied to fluctuating ice volume), resulting in cycles of emergence and submergence. In limnic systems it finds its most dramatic expression in alternations of lake and playa conditions. Biogenic pelagic oozes such as chalks and the limestones derived from them display variations in the carbonate supplied by planktonic organisms such as coccolithophores and foraminifera, and also record variations in the aeration of bottom waters. Whereas early studies of stratigraphic cyclicity relied mainly on bedding variations visible in the field, present studies are supplementing these with instrumental scans of geochemical, paleontological, and geophysical parameters which yield quantitative curves amenable to time-series analysis; such analysis is, however, limited by problems of distorted time-scales. My own work has been largely concentrated on pelagic systems. In these, the sensitivity of pelagic organisms to climatic-oceanic changes, combined with the sensitivity of botton life to changes in oxygen availability (commonly much more restricted in the Past than now) has left cyclic patterns related to orbital forcing. These systems are further attractive because (1) they tend to offer depositional continuity

  18. Tectonic and Climatic Implications of Late Miocene to Pleistocene (5.8-1.8 Ma) Paleo-Erosion Rates from the Rio Iruya Canyon, Northwest Argentina (23°S)

    Fisher, G. B.; Amidon, W. H.; Luna, L. V.; Burbank, D. W.

    2015-12-01

    One fundamental hypothesis that underpins tectonic geomorphology is that climate can modify the pattern and magnitude of erosion in orogenic landscapes and in turn control deformation. While conceptually appealing, empirical evidence is often ambiguous owing to the inherent spatial coupling between present-day tectonic and precipitation maxima and/or the long-term blurring of climate signals by thermochronologic techniques. Although cosmogenic nuclides provide considerable insight into centennial to millennial scale tectonic-erosion-climate linkages, extracting long-term records of erosion from older sedimentary deposits has proved challenging. If successful, such records have the potential to reveal long-term relationships between erosion, uplift, and climate, which should integrate over time to match long term exhumation rates obtained from low temperature thermochronology. Here we utilize a unique field setting along a 100-m deep, young canyon (~100 years old) along the Rio Iruya in northwestern Argentina to create a high-resolution (~100 kyr) terrestrial record of paleo-erosion rates in the eastern Cordillera spanning the late Miocene to Pleistocene (5.8-1.8 Mya). In total, 49 cosmogenic 10Be samples were analyzed along with detailed magnetostratigraphy, U-Pb tephra ages, detrital zircon, and quartz trace elements to yield a detailed paleo-erosion rate, chronology, and provenance record for the Rio Iruya section. Apparent erosion rates occur in three different regimes: from 5.8-4.0 Ma rates are high with little variability, from 4.0- 2.3 Ma rates oscillate by a factor of 5 on a ~400 kyr timescale, and from 2.3-1.8 Ma they are again high without clear oscillations. These three regimes correspond to changes in provenance recorded by detrital zircons and quartz chemistry, and suggest that during the late Pliocene the eastern Cordillera was responding strongly to the 400 kyr eccentricity paced orbital frequency. This unique finding is both perplexing and

  19. Activity of Cangbaishan Tianchi Volcano since Late Pleistocene: The constrain from geochronology of high precision U-series TIMS method%长白山天池火山晚更新世以来的喷发活动:

    王非; 陈文寄; 李齐; 彭子成

    2001-01-01

    Eleven samples of lava and pumice from the cone of ChangbaishanTianchi Volcano, Jiling, China, were dated by using high precision U-series TIMS method. The results show that the bottom of the cone formed before 350 ka, the middle part in 70 ~ 80 ka, the upper during 20 ~ 1 ka, and the top less than 1 ka, and the age based periods of the volcano eruption since Late Pleistocene is given as follows: > 350 ka, 70 ka, 18 ~ 25 ka, 10 ka,4 ~ 5 ka, 1 ~ 0. 75 ka, which may offer the basis for the study of volcanic disaster in future. In addition, the principle of dating young volcanic rocks by using U-series TIMS method is introduced briefly. Differentiation characteristics of U and Th in different minerals of the volcanic rocks are discussed, and the ability producing isochrons, based on U and Th differentiation, are discussed. In the last part of the paper, the closure of samples to the elements U and Th, which is important for age results, is discussed by using (234U/238U) radioactivity ratio which can be used to monitor if the samples have been weathered or eroded or leached since the time they formed.In this study, all samples have (234U/238U) activity ratios within 1% of secular equilibrium [(234U/238U)radioactivity ratios are unity), indicating no disturbance of the 234U-238U system. All of these discussions show that the TIMS method is good to date TianZhi volvanivs and the results are reliable.%应用高精度铀系不平衡TIMS法测定了吉林长白山天池火山岩锥体中上部的11个熔岩、浮岩样品的年龄,并据此划分出晚更新世、全新世以来6个喷发活动期次,分别为:>350ka、70ka、18~25ka、10ka、4~5ka和1~0.75ka。此外,还介绍了铀系不平衡法火山岩年代学的基本原理和试验流程,讨论了样品封闭性等问题。

  20. Stratigraphy -- The Fall of Continuity.

    Byers, Charles W.

    1982-01-01

    Reviews advances in stratigraphy as illustrated in the current geological literature, discussing discontinuity and how the recognition of discontinuity in the stratigraphic record is changing views of Superposition and Original Lateral Continuity. (Author/JN)

  1. International Commission on Stratigraphy (ICS)

    2005-01-01

    The International Commission on Stratigraphy (ICS) of IUGS is a body of expert stratigraphers founded for the purpose of promoting and coordinating long-term international cooperation and of establishing standards in stratigraphy. The ICS has five main objectives.

  2. Discussion on the evidence of three Late-Pleistocene "transgressions" in the western Taiwan Strait waters%台湾海峡西部海域晚更新世3次“海侵”依据的探讨

    周定成; 孙全; 许志峰

    2011-01-01

    晚更新世是全球气候环境与海陆变迁频繁的重要地质时期.通过对上世纪80年代采集的活塞柱状样(长度<6.5 m)的分析研究,曾提出晚更新世台湾海峡存在“金门海侵”、“福州海侵”、“海峡海侵”3次海侵.为提高台湾海峡第四纪地质研究和认知水平,本文探讨了3次“海侵”的立论依据,认为现有柱状样沉积层是晚更新世一全新世的浅表层沉积.台湾海峡具有开放性沉积条件,该浅表层沉积层的14C年龄数据应用于地层年代可能偏老.此3次“海侵”地层划分依据不足,存在疑点,尤其是“海峡海侵”.台湾海峡海底已发现数量及种类丰富的晚更新世各气候带陆生哺乳类动物遗骨,并有古人类遗骨化石,这些表明台湾海峡海底在玉木冰期鼎盛时期曾经出露成陆,并可能成为东亚大陆东缘冰期海退的海滨平原上,惟一有各种气候带古动物与古人类的生存地和避难地.%Late-Pleistocene was an important geological age witnessing frequent climatic environment and sea-land changes throughout the world. The events of Late-Pleistocene in Taiwan Strait, can be understood through the strata of that age. On the basis of the study of columnar samples ( <6.5 m) taken from the Taiwan Strait in the 1980s, three transgressions ("Jinmen", "Fuzhou", and "Strait" transgressions) in Late-Pleistocene were discovered. It was believed that the Taiwan Strait was a shallow sea environment with water depths of 30 ~ 60 m, and did not outcrop 18 000 a ago during the height of Wurm glaciation. The current study analyzed the evidence of these three transgressions, especially the "Strait Transgression". Firstly, the sedimentary layer of columnar samples makes us believe that it belongs to the superficial-surface sedimentary layer of Q3 - Q4. Since the Taiwan Strait has an open sedimentary environment, uC-dating of this layer may appear older than its chronological age. Late-Pleistocene

  3. Pleistocene Paleoart of Australia

    Robert G. Bednarik

    2014-02-01

    Full Text Available Pleistocene rock art is abundant in Australia, but has so far received only limited attention. Instead there has been a trend, begun over a century ago, to search for presumed depictions of extinct megafauna and the tracks of such species. All these notions have been discredited, however, and the current evidence suggests that figurative depiction was introduced only during the Holocene, never reaching Tasmania. Nevertheless, some Australian rock art has been attributed to the Pleistocene by direct dating methods, and its nature implies that a significant portion of the surviving corpus of rock art may also be of such age. In particular much of Australian cave art is of the Ice Age, or appears to be so, and any heavily weathered or patinated petroglyphs on particularly hard rocks are good candidates for Pleistocene antiquity. On the other hand, there is very limited evidence of mobiliary paleoart of such age in Australia.

  4. A phase-space model for Pleistocene ice volume

    Imbrie, John Z; Lisiecki, Lorraine E

    2011-01-01

    We present a phase-space model that simulates Pleistocene ice volume changes based on Earth's orbital parameters. Terminations in the model are triggered by a combination of ice volume and orbital forcing and agree well with age estimates for Late Pleistocene terminations. The average phase at which model terminations begin is approximately 90 +/- 90 degrees before the maxima in all three orbital cycles. The large variability in phase is likely caused by interactions between the three cycles and ice volume. Unlike previous ice volume models, this model produces an orbitally driven increase in 100-kyr power during the mid-Pleistocene transition without any change in model parameters. This supports the hypothesis that Pleistocene variations in the 100-kyr power of glacial cycles could be caused, at least in part, by changes in Earth's orbital parameters, such as amplitude modulation of the 100-kyr eccentricity cycle, rather than changes within the climate system.

  5. Coniacian-maastrichtian calcareous nannofossil biostratigraphy and carbon-isotope stratigraphy in the Zagros Basin (Iran)

    Razmjooei, Mohammad Javad; Thibault, Nicolas; Kani, Anoshiravan;

    2014-01-01

    Calcareous nannofossil biostratigraphy and stable isotope stratigraphy have been investigated in the Shahneshin section of the Gurpi Formation from the Zagros Basin (Iran). The results show that the Gurpi Formation spans the late early Coniacian to late Thanetian. The age-model shows that the...... magnetostratigraphy in the Santonian-early Campanian interval. The δ13C correlation, supported by calcareous nannofossil biostratigraphy, brings insights into: (1) the position of the Coniacian/Santonian, Santonian/Campanian and Campanian/Maastrichtian boundaries with respect to carbon-isotope stratigraphy and...

  6. Evaluation of the structure and stratigraphy over Richton Dome, Mississippi

    The structure and stratigraphy over Richton Salt Dome, Mississippi, have been evaluated from 70 borings that were completed to various depths above the dome. Seven lithologic units have been identified and tentatively correlated with the regional Tertiary stratigraphy. Structure-contour and thickness maps of the units show the effects of dome growth from Eocene through early Pliocene time. Growth of the salt stock from late Oligocene through early Pliocene is estimated to have averaged 0.6 to 2.6 centimeters (0.2 to 1.1 inches) per 1000 years. No dome growth has occurred since the early Pliocene. The late Oligocene to early Pliocene strata over and adjacent to the dome reflect arching over the entire salt stock; some additional arching over individual centers may represent pre-Quaternary differential movement in the salt stock. The lithology and structure of the caprock at the Richton Salt Dome indicate that the caprock probably was completely formed by late Oligocene. In late Oligocene, the caprock was fractured by arching and altered by gypsum veining. Since late Oligocene, there are no indications of significant hydrologic connections through the caprock - that is, there are no indications of dissolution collapse or further anhydrite caprock accumulation. This structural and stratigraphic analysis provides insights on dome growth history, dome geometry, and neardome hydrostratigraphy that will aid in planning site characterization field activities, including an exploratory shaft, and in the conceptual design of a high-level waste (HLW) repository

  7. Stratigraphy of the crater Copernicus

    Paquette, R.

    1984-01-01

    The stratigraphy of copernicus based on its olivine absorption bands is presented. Earth based spectral data are used to develop models that also employ cratering mechanics to devise theories for Copernican geomorphology. General geologic information, spectral information, upper and lower stratigraphic units and a chart for model comparison are included in the stratigraphic analysis.

  8. Global stratigraphy. [of planet Mars

    Tanaka, Kenneth L.; Scott, David H.; Greeley, Ronald

    1992-01-01

    Attention is given to recent major advances in the definition and documentation of Martian stratigraphy and geology. Mariner 9 provided the images for the first global geologic mapping program, resulting in the recognition of the major geologic processes that have operated on the planet, and in the definition of the three major chronostratigraphic divisions: the Noachian, Hesperian, and Amazonian Systems. Viking Orbiter images permitted the recognition of additional geologic units and the formal naming of many formations. Epochs are assigned absolute ages based on the densities of superposed craters and crater-flux models. Recommendations are made with regard to future areas of study, namely, crustal stratigraphy and structure, the highland-lowland boundary, the Tharsis Rise, Valles Marineris, channels and valley networks, and possible Martian oceans, lakes, and ponds.

  9. Cycles and events in stratigraphy

    Einsele, G.; Ricken, W.; Seilacher, A. (eds.)

    1991-01-01

    This book reviews and discusses the most up-to-date knowledge in the fields of cyclostratigraphy and event stratigraphy. The book contains 48 papers contributed by the most knowledgeable geologists and paleontologists in the fields of cycle and event stratigraphy. It is divided into two parts. Part one is concerned with the structure of individual beds and larger cycles and sequences and discusses; rhythmic stratification, event stratification, diagenetic overprint, cherts and phosphorites, and preservation and biologic destruction of laminated sediments. Part two, on larger cycles and sequences, looks at sequences, hierarchies, causes and environmental expression, and timing and correlation, i.e. the cycles of frequencies from millions of years to thousands of years (Milankovich band). Summaries on spectral analysis are also presented. There are 80 pages of references and a comprehensive index. It is extensively illustrated with line drawings and graphs. Practicing sedimentary geologists without access to a good library or find it hard to keep up with the plethora of journal articles and want a refresher in this area of stratigraphy will find the book particularly useful.

  10. OSTEOMETRÍA DE VICUGNA VICUGNA MOLINA, 1782 EN EL PLEISTOCENO FINAL DE PATAGONIA MERIDIONAL CHILENA: IMPLICANCIAS PALEOECOLÓGICAS Y BIOGEOGRÁFICAS / Osteometry of Vicugna vicugna Molina, 1782 in the late Pleistocene of southern chilean Patagonia

    Rafael Labarca Encina

    2009-12-01

    Full Text Available  Se presenta un análisis osteométrico uni y multivariado con los materiales fósiles -principalmente huesos cortos y falanges- de Vicugna sp. del yacimiento Cueva Lago Sofía 4 (13500 – 11000 AP, ubicado en la provincia de Última Esperanza (Región de Magallanes, Chile. Los resultados indican que los elementos analizados poseen un tamaño compatible con los registrados para Vicugna vicugna, no superando en ningún caso a los especímenes conocidos para Vicugna gracilis del Pleistoceno de la región Pampeana. Esto confirma la información morfológica y de ADN antiguo que indicaba la presencia de Vicugna vicugna en la Patagonia meridional chilena. Se discuten los resultados en términos taxonómicos, biogeográficos y paleoecológicos sugiriendo que la presencia de este taxón fuera de su rango actual de distribución se debió a las condiciones ambientales compartidas entre la Puna y Patagonia austral durante la transición Pleistoceno-Holoceno. La extinción de V. vicugna se habría debido al impacto de los cambios climáticos ocurridos al inicio del Holoceno producto de su dieta pastadora y etología no migratoria y territorial, a lo que se habría sumado una caza por parte de depredadores humanos y no humanos.Palabras clave: género Vicugna, osteometría, Pleistoceno, Patagonia AbstractThis contribution presents the results of single and multi-variable osteometric analyses performed on a sample of short bones and phalanxes assigned to Vicugna sp. from Lago Sofía Cave 4 site (13500 – 11000 BP, Región de Magallanes, Chile. The elements analyzed show a similar size to the reference collections for Vicugna vicugna, and do not exceed the metrics for the pampean pleistocenic specimens of Vicugna gracilis. This confirms the morphological and ancient DNA data that indicated the presence of vicuña in southern Chilean Patagonia. The taxonomic, biogeographic and palaeoecologic discussion of these results, suggests that the presence of this

  11. Carboniferous-Permian sedimentology and stratigraphy of the Nordfjorden High and Loppa Spur, Arctic Norway

    Ahlborn, Morten

    Abstract (shortened) Facies analysis of Late Paleozoic warm-water carbonates, were conducted in order to investigate the depositional evolution, cyclicity, internal architecture and sequence stratigraphy of the upper Gipsdalen Group carbonate platform on the Nordfjorden High in central Spitsbergen...... the evolution of the Northern Pangean margin. In this study, the emphasis has been to understand the warm-water carbonate deposition, cyclicity, sequence stratigraphy and subaerial exposure events in high resolution across a structural high, all problems not fully understood so far in the Barents Sea...

  12. Changing sedimentary environments during Pleistocene-Holocene in a core from the eastern continental margin of India

    Rao, V.P.; Rao, Ch.M.; Mascarenhas, A.; Rao, K.M.; Reddy, N.P.C.; Das, H.C.

    Sedimentological and geochemical investigations of the sediments in a core from the eastern continental margin of India, at a water depth of 1200 m, revealed two distinct types. The Late Pleistocene sediments are greyish-black in colour and consist...

  13. Identification of greigite in the late Pleistocene sediments of Lake Qinghai and its environmental implications%青海湖晚更新世沉积物中胶黄铁矿的发现及其环境指示意义

    艾莉; 强小科; 宋友桂; 敖红; 安芷生

    2011-01-01

    对青海湖南盆沉积中心钻取的一根长18.6 m的高取芯率沉积岩芯(1F)进行磁化率测试显示,该岩芯在8.15~8.96 m和15.50~17.28m两沉积段具有非常高的磁化率.详细的岩石磁学测量和矿物分析表明这两段沉积物中有大量的胶黄铁矿存在,其磁畴特征主要以单畴(SD)为主,并显示少量超顺磁(SP)颗粒特征,这是导致磁化率大幅升高的主要原因.胶黄铁矿的生成与硫酸盐还原作用密切相关,1F沉积岩芯中胶黄铁矿的发现表明青海湖在晚更新世具有非常适宜胶黄铁矿生成的硫酸盐还原环境.%Lake Qinghai, the largest lake in China, is situated in an important climate-sensitive zone on the northeastern margin of Tibetan Plateau. In this study, the magnetic mineralogy of a late Pleistocene sediment core (1F, 18. 6 m long) from the southern sub-basin deposition center of Lake Qinghai was studied using multiple rock-magnetic and non-magnetic measurements. There are two distinct magnetic susceptibility peaks at the depths of 8. 15~8. 96 m and 15. 50 - 17. 28 m. High- and low-temperature magnetic measurements, coupled with scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analyses, suggest that the sediments from these two intervals contain a large number of single domain (SD) and some superparamagnetic (SP) greigite particles, which is the primary cause for the enhancement of magnetic susceptibility. Greigite particles are mainly formed due to sulfate reduction, an early stage of diagenesis. Therefore, the occurrence of greigite in 1F core implies that the Lake Qinghai could have experienced two intervals favorable for early diagenesis during the late Pleistocene.

  14. A partial distal humerus from the Middle Pleistocene deposits at Bodo, Middle Awash, Ethiopia

    Carretero, José Miguel; Haile Selassie, Yohannes; Rodríguez García, Laura; Arsuaga, Juan Luis

    2009-01-01

    The Bodo partial distal humerus with an approximate age of 0.6 million years is one of the very few postcranial remains from the African Middle Pleistocene. Despite its fragmentary status, comparisons of the Bodo humerus with other fossil hominid and modern human samples reveal some insights into African hominids of this time period. The Bodo partial humerus displays distal humeral features very common in the European Middle and Late Pleistocene hominids, such as a relatively w...

  15. Megafauna and ecosystem function from the Pleistocene to the Anthropocene.

    Malhi, Yadvinder; Doughty, Christopher E; Galetti, Mauro; Smith, Felisa A; Svenning, Jens-Christian; Terborgh, John W

    2016-01-26

    Large herbivores and carnivores (the megafauna) have been in a state of decline and extinction since the Late Pleistocene, both on land and more recently in the oceans. Much has been written on the timing and causes of these declines, but only recently has scientific attention focused on the consequences of these declines for ecosystem function. Here, we review progress in our understanding of how megafauna affect ecosystem physical and trophic structure, species composition, biogeochemistry, and climate, drawing on special features of PNAS and Ecography that have been published as a result of an international workshop on this topic held in Oxford in 2014. Insights emerging from this work have consequences for our understanding of changes in biosphere function since the Late Pleistocene and of the functioning of contemporary ecosystems, as well as offering a rationale and framework for scientifically informed restoration of megafaunal function where possible and appropriate. PMID:26811442

  16. A mitochondrial stratigraphy for island southeast Asia.

    Hill, Catherine; Soares, Pedro; Mormina, Maru; Macaulay, Vincent; Clarke, Dougie; Blumbach, Petya B; Vizuete-Forster, Matthieu; Forster, Peter; Bulbeck, David; Oppenheimer, Stephen; Richards, Martin

    2007-01-01

    Island Southeast Asia (ISEA) was first colonized by modern humans at least 45,000 years ago, but the extent to which the modern inhabitants trace their ancestry to the first settlers is a matter of debate. It is widely held, in both archaeology and linguistics, that they are largely descended from a second wave of dispersal, proto-Austronesian-speaking agriculturalists who originated in China and spread to Taiwan approximately 5,500 years ago. From there, they are thought to have dispersed into ISEA approximately 4,000 years ago, assimilating the indigenous populations. Here, we demonstrate that mitochondrial DNA diversity in the region is extremely high and includes a large number of indigenous clades. Only a fraction of these date back to the time of first settlement, and the majority appear to mark dispersals in the late-Pleistocene or early-Holocene epoch most likely triggered by postglacial flooding. There are much closer genetic links to Taiwan than to the mainland, but most of these probably predated the mid-Holocene "Out of Taiwan" event as traditionally envisioned. Only approximately 20% at most of modern mitochondrial DNAs in ISEA could be linked to such an event, suggesting that, if an agriculturalist migration did take place, it was demographically minor, at least with regard to the involvement of women. PMID:17160892

  17. Oxygen isotope stratigraphy in the Gulf of Alaska (IODP Exp. 341)

    Asahi, H.; Mix, A. C.; Suto, I.; Belanger, C. L.; Fukumura, A.; Gupta, S.; Konno, S.; Matsuzaki, K. M.; Romero, O. E.; Gulick, S. P. S.; Jaeger, J. M.; Schneider, L. J.

    2014-12-01

    Age constrains provided by oxygen isotope stratigraphy, biostratigraphy and paleomagnetics can provide fundamental insights for interpreting other paleoceanographic reconstructions at orbital scale. In the case of the high latitude in the North Pacific, most paleoceanographic studies investigating the evolution of the North Pacific climate since the intensification of Northern Hemisphere Glaciation (iNHG) face difficulties in establishing orbital-scale age models due to the low preservation of foraminifer fossils. Most North Pacific studies targeting the Pleistocene heavily rely on alternative approaches with higher preservation potential (e.g. MS: Magnetic Susceptibility) for orbital-scale age models, and assume such data are mainly reflecting the Glacial-Interglacial (G-IG) cycle. A continuous oxygen iope record from the subarctic North Pacific is long anticipated data set to test such assumptions. Two sites (Sites U1417 and U1418) in the Gulf of Alaska (GoA) drilled during IODP Exp. 341 are expected to provide continuous sediment records back to the middle Pleistocene (U1418) and Miocene (U1417), respectively. Here we present age models at Sites U1417 and U1418 derived from refined biostratigraphy and planktic foraminiferal (PF) oxygen isotope (Neogloboquadrina pachyderma sinistral, 150-250 μm fraction) stratigraphy (~1.2Ma at Site U1418 and ~3.0Ma at U1417, respectively). General agreement between oxygen isotope stratigraphy and other age constraints (biostratigraphy and paleomagnetism) at Site U1418 confirms the reliability of those age models. Furthermore, general trends seen in PF oxygen isotope time series roughly matches MS, suggesting that MS can be used for further age model tuning or as an alternative solution for the orbital scale age constrains in the GoA.

  18. Pleistocene vertebrates of Silicon Valley (Santa Clara County, California)

    Maguire, Kaitlin Clare; Holroyd, Patricia A.

    2016-01-01

    Here we report on late Pleistocene fossil vertebrates from new and previously described localities in Santa Clara County, California. The three new localities and specimens include: a partial mammoth pelvis from UCMP V91128 (Lawrence Expressway E); a juvenile cranial specimen of Mammuthus columbi from UCMP V99597 (SCVWD “Lupe” Mammoth), now on display at the San Jose Children’s Discovery Center; and a relatively diverse assemblage of medium- to large-sized mammals, including a nearly complete...

  19. Revised stratigraphy and chronology for Homo floresiensis at Liang Bua in Indonesia

    Sutikna, Thomas; Tocheri, Matthew W; Morwood, Michael J;

    2016-01-01

    Homo floresiensis, a primitive hominin species discovered in Late Pleistocene sediments at Liang Bua (Flores, Indonesia), has generated wide interest and scientific debate. A major reason this taxon is controversial is because the H. floresiensis-bearing deposits, which include associated stone...

  20. Contribution of stable isotopes (C,N,S) in collagen of late Pleistocene large mammal trophic ecology and landscape use: a case study in Goyet and Scladina cave (30-40,000 years BP)

    Bocherens, Hervé; Germonpré, Mietje

    2010-05-01

    Two Belgian caves yielded very rich large mammal associations dating around 30 to 40,000 years ago: Goyet and Scladina cave (layer 1A). These sites are only 5 km apart but the cave entrances open on different valleys, in a quite diverse landscape ranging between open, unprotected uplands, steep cliffs and sheltered sun-exposed gorges, with the larger Meuse valley nearby. This mosaic scenery permitted during the Last Glacial a rich diversity of fossil flora and fauna. The faunal association includes a large diversity of taxa including Aurochs Bos primigenius, steppe bison Bison priscus, reindeer Rangifer tarandus, giant deer Megaloceros giganteus, horse Equus ferus, woolly rhinoceros Coelodonta antiquitatis, woolly mammoth Mammuthus primigenius, cave bear Ursus spelaeus, brown bear Ursus arctos, wolf Canis lupus, cave lion Panthera leo spelaea, and cave hyaena Crocuta crocuta spelaea. All the 90 studied bones and teeth yielded collagen with excellent collagen preservation, allowing reliable investigations of carbon, nitrogen and sulfur isotopic biogeochemistry. The combination of three different isotopic tracers allows to deciphering the effects of food selection and landscape use by different herbivorous and carnivorous taxa. This is the first study to include sulfur isotopic signatures in the study of late Quaternary large mammal palaeobiology. This new tracer yields evidence on mobility and differences in pasture areas, as different geological bedrock may exhibit various sulfur isotopic signatures that will pass on the herbivores and further on their predators. Using this feature in addition to the trophic information provided by carbon and nitrogen isotopic signatures, it appears that for some species present in both sites, such as horse and woolly rhinoceros, the individuals found in each site probably did not use the same pasture areas. This seems to also the case for the overwhelmingly vegetarian cave bears. In addition, individuals from the same species

  1. Obliquity and precession as pacemakers of Pleistocene deglaciations

    Feng, Fabo

    2015-01-01

    The Milankovitch theory states that the orbital eccentricity, precession, and obliquity of the Earth influence our climate by modulating the summer insolation at high latitudes in the northern hemisphere. Despite considerable success of this theory in explaining climate change over the Pleistocene epoch (2.6 to 0.01 Myr ago), it is inconclusive with regard to which combination of orbital elements paced the 100 kyr glacial-interglacial cycles over the late Pleistocene. Here we explore the role of the orbital elements in pacing the Pleistocene deglaciations by modeling ice-volume variations in a Bayesian approach. When comparing models, this approach takes into account the uncertainties in the data as well as the different degrees of model complexity. We find that the Earth's obliquity (axial tilt) plays a dominant role in pacing the glacial cycles over the whole Pleistocene, while precession only becomes important in pacing major deglaciations after the transition of the dominant period from 41 kyr to 100 kyr ...

  2. Pleistocene Palaeoart of the Americas

    Robert G. Bednarik

    2014-04-01

    Full Text Available In contrast to the great time depth of Pleistocene rock art and mobiliary ‘art’ in the four other continents, the available evidence from the Americas is very limited, and restricted at best to the last part of the final Pleistocene. A review of what has so far become available is hampered by a considerable burden of literature presenting material contended to be of the Ice Age, even of the Mesozoic in some cases, that needs to be sifted through to find a minute number of credible claims. Even the timing of the first colonization of the Americas remains unresolved, and the lack of clear-cut substantiation of palaeoart finds predating about 12,000 years bp is conspicuous. There are vague hints of earlier human presence, rendering it likely that archaeology has failed to define its manifestations adequately, and Pleistocene palaeoart remains almost unexplored at this stage.

  3. A ~276 years cyclicity of western pacific coastal upwelling during Late Pleistocene (Termination I) and Holocene as revealed by the microscale facies and elemental analysis of the varved record of Saanich Inlet, BC

    Kanamaru-Shinn, K.; Francus, P.; Jercinovic, M. J.

    2009-12-01

    occurrences of these events are roughly every 276 years, except between 4585 and 2420 C14 cal yr BP where no elemental data is obtained, and between 9923 and 8474 C14 cal yr BP when sediments are significantly disturbed. Furthermore, coupling of EDS and image analyses illustrates that there is evidence of a shift in precipitation season during the Holocene. Illite appearance, which suggests a Fraser Lowland provenance, shifts from late winter in the early Holocene to early spring in the mid-Holocene, indicating a change in the timing of major snowmelt events. Micro-scale sediment analyses, including sediment facies, processes, and chemical compositions, are proved to be efficient tools for analyzing and assessing sediment provenance.

  4. Mechanical stratigraphy of deep-water sandstones: insights from a multisciplinary field and laboratory study

    Agosta, Fabrizio; di Celma, Claudio; Tondi, Emanuele; Corradetti, Amerigo; Cantalamessa, Gino

    2010-05-01

    -perpendicular joint spacing/bed thickness (S/T) relationships on sandstone bodies that experienced similar diagenetic and tectonic histories. The field area is located in the Periadriatic foreland basin, eastern central Italy, which show late Pliocene slope turbidites in excellent 3d views. The Periadriatic foreland basin is an elongated, roughly N-S oriented trough located immediately east of the Apennines fold-thrust belt. The basin fill mostly consists of deepwater Plio-Pleistocene sediments partially incorporated into the frontal part of the orogenic wedge. During the late Pliocene, gravel and sand originated from the uplifting Apennines were abundantly supplied to the deep-water basin through a series of erosional conduits that, in the rock record, appear as a series of N-S oriented slope submarine canyon systems deeply incised into the hemipelagic mudstones of the adjacent slope. The studied exposure allows direct observation of spatial and temporal relationships among the various depositional elements comprising the canyon system and related lithofacies, as well as the bed-perpendicular joint density within each lithofacies. We performed a multidisciplinary work involving the following tasks: (i) 3D stratigraphic model of the depositional architecture of the Castignano and Ascensione canyon systems (Marche region, Italy); (ii) 2D scanline survey of several outcrops displaying bed-perpendicular joints; (iii) digital image analysis of selected thin-section obtained from oriented hand samples to characterize the 3D intergranualr porosity; (iv) Stiffness analysis of representative sandstone bodies by mean of Schmidt hammer tests. The first results of this ongoing study on the mechanical stratigraphy of the two Late Pliocene canyon systems are consistent with the joint density being effected by both geometrical (i.e., bed thickness) and mechanical properties. This data set will help field and experimental geologists to better define common strategies to assess the controlling

  5. Remanent magnetization stratigraphy of lunar cores

    Banerjee, S. K.; Gingrich, D.; Marvin, J. A.

    1977-01-01

    Depth dependent fluctuations have been observed in the natural remanent magnetizations (NRM) of drive cores and drill strings from Apollo 16 and 17 missions. Partial demagnetization of unstable secondary magnetizations and identification of characteristic error signals from a core which is known to have been recently disturbed allow us to identify and isolate the stable NRM stratigraphy in double drive core 60010/60009 and drill strings 60002-60004. The observed magnetization fluctuations persist after normalization to take into account depth dependent variations in the carriers of stable NRM. We tentatively ascribe the stable NRM stratigraphy to instantaneous records of past magnetic fields at the lunar surface and suggest that the stable NRM stratigraphy technique could develop as a new relative time-stratigraphic tool, to be used with other physical measurements such as relative intensity of ferromagnetic resonance and charged particle track density to study the evolution of the lunar regolith.

  6. Early pleistocene sediments at Great Blakenham, Suffolk, England

    Gibbard, P. L.; Allen, P.; Field, M. H.; Hallam, D. F.

    Detailed investigation of a fine sediment sequence, the College Farm Silty Clay Member, that overlies the Creeting Sands (Early Pleistocene) in Suffolk, is presented. The sedimentary sequence is thought to represent a freshwater pool accumulation in a small coastal embayment. Palaeobotanical investigation of the sediment indicates that it accumulated during the late temperate substage of a temperate (interglacial) event. The occurrence of Tsuga pollen, associated with abundant remains of the water fern Azolla tegeliensis indicate that the deposits are of Early Pleistocene age and are correlated with a later part of the Antian-Bramertonian Stage. Correlation with Tiglian TO substage in The Netherlands' sequence is most likely. The sediments' normal palaeomagnetic polarity reinforces the biostratigraphical correlation.

  7. Complete mitochondrial genome and phylogeny of Pleistocene mammoth Mammuthus primigenius.

    Evgeny I Rogaev

    2006-03-01

    Full Text Available Phylogenetic relationships between the extinct woolly mammoth (Mammuthus primigenius, and the Asian (Elephas maximus and African savanna (Loxodonta africana elephants remain unresolved. Here, we report the sequence of the complete mitochondrial genome (16,842 base pairs of a woolly mammoth extracted from permafrost-preserved remains from the Pleistocene epoch--the oldest mitochondrial genome sequence determined to date. We demonstrate that well-preserved mitochondrial genome fragments, as long as approximately 1,600-1700 base pairs, can be retrieved from pre-Holocene remains of an extinct species. Phylogenetic reconstruction of the Elephantinae clade suggests that M. primigenius and E. maximus are sister species that diverged soon after their common ancestor split from the L. africana lineage. Low nucleotide diversity found between independently determined mitochondrial genomic sequences of woolly mammoths separated geographically and in time suggests that north-eastern Siberia was occupied by a relatively homogeneous population of M. primigenius throughout the late Pleistocene.

  8. Investigation of sea-level changes and shelf break prograding sequences during the Late Quaternary offshore of Kusadasi (West Anatolia) and surroundings by high resolution seismic methods

    Gurcay, Savas; Cifci, Gunay; Dondurur, Derman; Okay, Seda; Atgin, Orhan; Ozel, Ozkan; Mert Kucuk, Hilmi

    2016-04-01

    High Resolution multi-channel seismic reflection and Chirp data were collected by K. Piri Reis, research vessel of Dokuz Eylül University, in the central Aegean coast of the West Anatolia by research cruises carried out in 2005 and 2008, respectively. Submarine stratigraphic and structural features of Sıǧacık Gulf, Kuşadası Gulf and surroundings were investigated under this survey. The data were processed and interpreted in SeisLab, D.E.U. Marine Sciences and Technology seismic laboratory. Thirteen distinct unconformities can be traced below the study area that separate thirteen progradational stacked paleo-delta sequences (Lob1-Lob13) on seismic profiles following and cutting each other. As a result of comparison with the oxygen isotopic stages (δ18), these deltas (Lob1-L13) were interpreted that they have been deposited during the sea-level lowstands within Pleistocene glacial stages. In the study area the basement surface which observed as the lowest unconformity surface of the seismic sections was called 'Acoustic Basement'. This basement which traced approximately all of the seismic sections has generally quite wavy surface and underlain the upper seismic units. It was observed that these seismic units which terminated their formation in Pleistocene (Lob1-Lob13) and Holocene period were cut and uplifted by acoustic basement, like an intrusion. These type deformations were interpreted as a result of magmatic intrusion into these upper seismic units occurred in Late Pleistocene and Holocene period. Tectonic and structural interpretation was carried out to constitute the submarine active tectonic map of the study area by correlated active faults identified on seismic sections. Submarine active tectonic map and, basement topography and sediment thickness map were correlated together to present the relationship between tectonic deformation and stratigraphy.

  9. Late Quaternary activity along the Scorciabuoi Fault (Southern Italy as inferred from electrical resistivity tomographies

    A. Loperte

    2007-06-01

    Full Text Available The Scorciabuoi Fault is one of the major tectonic structures affecting the Southern Apennines, Italy. Across its central sector, we performed several electrical resistivity tomographies with different electrode spacing (5 and 10 m and using a multielectrode system with 32 electrodes. All tomographies were acquired with two different arrays, the dipole-dipole and the Wenner-Schlumberger. We also tested the different sensitivity of the two arrays with respect to the specific geological conditions and research goals. Detailed geological mapping and two boreholes were used to calibrate the electrical stratigraphy. In all but one tomography (purposely performed off the fault trace, we could recognise an abrupt subvertical lateral variation of the main sedimentary bodies showing the displacement and sharp thickening of the two youngest alluvial bodies in the hanging-wall block. These features are interpreted as evidence of synsedimentary activity of the Scorciabuoi Fault during Late Pleistocene and possibly as recently as Holocene and allow accurate location of the fault trace within the Sauro alluvial plain.

  10. The temporal bones from Sima de los Huesos Middle Pleistocene site (Sierra de Atapuerca, Spain). A phylogenetic approach.

    Martínez, I; Arsuaga, J L

    1997-01-01

    Three well-preserved crania and 22 temporal bones were recovered from the Sima de los Huesos Middle Pleistocene site up to and including the 1994 field season. This is the largest sample of hominid temporal bones known from a single Middle Pleistocene site and it offers the chance to characterize the temporal bone morphology of an European Middle Pleistocene population and to study the phylogenetic relationships of the SH sample with other Upper and Middle Pleistocene hominids. We have carried out a cladistic analysis based on nine traits commonly used in phylogenetic analysis of Middle and Late Pleistocene hominids: shape of the temporal squama superior border, articular eminence morphology, contribution of the sphenoid bone to the median glenoid wall, postglenoid process projection, tympanic plate orientation, presence of the styloid process, mastoid process projection, digastric groove morphology and anterior mastoid tubercle. We have found two autapomorphies on the Home erectus temporal bone: strong reduction of the postglenoid process and absence of the styloid process. Modern humans, Neandertals and the Middle Pleistocene fossils from Europe and Africa constitute a clade characterized by a convex superior border of the temporal squama. The European Middle Pleistocene fossils from Sima de los Huesos, Petralona, Steinheim, Bilzingsleben and Castel di Guido share a Neandertal apomorphy: a relatively flat articular eminence. The fossils from Ehringsdorf, La Chaise Suardi and Biache-Saint-Vaast also display another Neandertal derived trait: an anteriorly obliterated digastric groove. Modern humans and the African Middle Pleistocene fossils share a synapomorphy: a sagittally orientated tympanic plate. PMID:9300344

  11. Stratigraphy and dissolution of the Rustler Formation

    This report describes the physical stratigraphy of the Rustler Formation, because the Waste Isolation Pilot Plant will be constructed in salt beds that underlie this formation. Described are subdivisions of the formations, the major karst features, and a proposed method for the formation of Nash Draw. 2 refs., 2 figs

  12. Macro fossils vegetable in Palmar formation (later pleistocene) in Entre Rios - Argentina

    This work is about the macro fossil knowledge preserved like wood fossils in the El Palmar Formation (Late Pleistocene) from a systematic - anatomical as well as paleoecological and paleoclimate point of view.The paleo Flora comes from various fossil located in the province of Entre Rios - Argentina

  13. Problems of Sequence Stratigraphy in China

    2000-01-01

    A comprehensive study of outcrop sequence stratigraphy in China began in the early 1990s.The investigated strata range from Mesoproterozoic to Quaternary and the studied areas cover the three platforms and margins, the Southern Himalayas and the East China and South China seas.Problems of general concern in the sequence stratigraphy of China are discussed. These are: the hierarchy for sequence stratigraphy, the third-order Sequence and eustasy, the chronostratigraphic boundaries and GSSP, and the International Stratigraphic Chart and the sequence chronostratigraphy of China. The average time interval of Mesosequence (25-40 Ma) and of the Sequence (2-5 Ma) is suggested and the minor sequences below the Sequence are discussed. The time interval of the Sequence shows no evident decrease with time, but several epochs with remarkable short intervals occur in the Phanerozoic, which may represent a planetary behavior denoting the special development stages in earth's evolution. Sea level change curves are given separately for the three platforms and the different regions. The Global Stratotype Section and Point (GSSP) concept and practice are discussed, and a comparison between the first appearance point of biozone and the first flooding surface in the Sequence is made for designation of the chronostratigraphic boundary.It is suggested that the chronostratigraphic boundaries might be set at the first flooding surface in the Sequence for easy recognition. The idea of sequence chronostratigraphy is recommended, and a comparison between the International Stratigraphic Chart and the sequence chronostratigraphy of China is made. The close relation between chronostratigraphy and sequence stratigraphy makes it possible for sequence stratigraphy to improve chronostratigraphic research. It is pointed out that multidisciplinary study in chronostratigraphy is necessary and should be promising and profitable.

  14. New U/Th ages for Pleistocene megafauna deposits of southeastern Queensland, Australia

    Price, Gilbert J.; Zhao, Jian-xin; Feng, Yue-xing; Hocknull, Scott A.

    2009-02-01

    Arguments over the extinction of Pleistocene megafauna have become particularly polarised in recent years. Causes for the extinctions are widely debated with climate change, human hunting and/or habitat modification, or a combination of those factors, being the dominant hypotheses. However, a lack of a spatially constrained chronology for many megafauna renders most hypotheses difficult to test. Here, we present several new U/Th dates for a series of previously undated, megafauna-bearing localities from southeastern Queensland, Australia. The sites were previously used to argue for or against various megafauna extinction hypotheses, and are the type localities for two now-extinct Pleistocene marsupials (including the giant koala, Phascolarctos stirtoni). The new dating allows the deposits to be placed in a spatially- and temporally constrained context relevant to the understanding of Australian megafaunal extinctions. The results indicate that The Joint (Texas Caves) megafaunal assemblage is middle Pleistocene or older (>292 ky); the Cement Mills (Gore) megafaunal assemblage is late Pleistocene or older (>53 ky); and the Russenden Cave Bone Chamber (Texas Caves) megafaunal assemblage is late Pleistocene (˜55 ky). Importantly, the new results broadly show that the sites date prior to the hypothesised megafaunal extinction 'window' (i.e., ˜30-50 ky), and therefore, cannot be used to argue exclusively for or against human/climate change extinction models, without first exploring their palaeoecological significance on wider temporal and spatial scales.

  15. Late Pleistocene temperature history of Southeast Africa: A TEX

    Woltering, M.; Johnson, T.C.; Werne, J.P.; Schouten, S.; Sinninghe Damsté, J.S.

    2011-01-01

    We present a TEX86-derived surface water temperature record for Lake Malawi that provides the first continuous continental record of temperature variability in the continental tropics spanning the past similar to 74 kyr with millennial-scale resolution. Average temperature during Marine Isotope Stag

  16. Preliminary Cosmogenic Nuclide Chronology of Late Pleistocene Missoula Floods

    Balbas, A.; Clark, J.; Clark, P. U.; Caffey, M. W.; Woodruff, T. E.; Baker, V. R.

    2014-12-01

    The Missoula floods had the largest known peak flood discharges of fresh water known from the geologic record. Multiple floods are believed to have originated from the failure of the Purcell trench ice lobe, which dammed glacial Lake Missoula. The flood waters traveled westward creating the Channeled Scabland region, a spectacular complex of anastomosing channels, coulees, cataracts, loess islands, rock basins, broad gravel deposits, and immense gravel bars in east-central Washington State. Several important questions about the Missoula floods and the formation of the Channeled Scabland remain, primarily due to the few geochronological constraints on their timing. Attempts to date the duration of the multiple floods have produced a wide range of ages (13-19 ka from land deposits and 13-31 ka from marine cores), but few of these directly constrain the age of the major flood landscape elements. Here we present 14 new in situ cosmogenic 10Be ages from quartz-bearing boulders deposited at four sites in eastern Washington. Wallula Gap is a narrow constriction along the Columbia River between Oregon and Washington. Hydraulic damming of floodwater at Wallula Gap created glacial Lake Lewis. Surface exposure ages on large boulders found at over 300 m elevation above the river at this site will date the largest flood events. The Wenatchee region represents the most northwestern area influenced by flooding. Dates from this area will determine when flooding occurred after the retreat of the Okanogan lobe. We sampled boulders from the lower Pangborn Bar, ice-rafted boulders north of Wenatchee, and boulders from a flood bar on the Columbia River north of Wenatchee. A boulder from the Mattawa Fan was sampled to assess the last time a megaflood came through the Sentinel Gap. Finally, in order to constrain the last debris dam failure at the southern end of the Upper Grand Coulee, we sampled flood boulders deposited on the Ephrata Fan.

  17. Climate variability of the tropical Andes since the late Pleistocene

    A. Bräuning

    2009-10-01

    Full Text Available Available proxy records witnessing palaeoclimate of the tropical Andes are comparably scarce. Major implications of palaeoclimate development in the humid and arid parts of the Andes are briefly summarized. The long-term behaviour of ENSO has general significance for the climatic history of the Andes due to its impact on regional circulation patterns and precipitation regimes, therefore ENSO history derived from non-Andean palaeo-records is highlighted. Methodological constraints of the chronological precision and the palaeoclimatic interpretation of records derived from different natural archives, such as glacier sediments and ice cores, lake sediments and palaeo-wetlands, pollen profiles and tree rings are addressed and complementary results concerning former climatic conditions are discussed in terms of possible implications of former atmospheric circulation patterns and main climatic forcing factors. During the last years, increasing tree-ring information is getting available from the tropical Andes, providing high-resolution climate-sensitive records covering the past centuries for the study of climate variability.

  18. Role of regional extension and uplift in the Plio-Pleistocene evolution of the Aksu Basin, SW Turkey

    Glover, Clare P; Robertson, Alastair H F

    1998-01-01

    The Aksu Basin, within the Isparta Angle area of SW Turkey, documents Plio-Pleistocene crustal processes at the interface between the Tauride Mountains and the Eastern Mediterranean Sea. Basin sedimentation began in the Late Miocene, following an earlier history of emplacement of Mesozoic allochthonous units (Antalya Complex), Miocene basin development and localized Late Miocene compression (Aksu Phase). Late Miocene–Early Pliocene transtension deformed the Aksu Basin, exploiting pre-existing...

  19. Stratigraphy of the Martian northern plains

    Tanaka, K. L.

    1993-01-01

    The northern plains of Mars are roughly defined as the large continuous region of lowlands that lies below Martian datum, plus higher areas within the region that were built up by volcanism, sedimentation, tectonism, and impacts. These northern lowlands span about 50 x 10(exp 6) km(sup 2) or 35 percent of the planet's surface. The age and origin of the lowlands continue to be debated by proponents of impact and tectonic explanations. Geologic mapping and topical studies indicate that volcanic, fluvial, and eolian deposition have played major roles in the infilling of this vast depression. Periglacial, glacial, fluvial, eolian, tectonic, and impact processes have locally modified the surface. Because of the northern plains' complex history of sedimentation and modification, much of their stratigraphy was obscured. Thus the stratigraphy developed is necessarily vague and provisional: it is based on various clues from within the lowlands as well as from highland areas within and bordering the plains. The results are summarized.

  20. Thermoluminescence dating of pleistocene sediments

    After a short introduction on recent trends in quaternary geochronology, this article focuses on the thermoluminescence dating of sediments, whose principles and present limits and prospects are discussed. Results are presented for the TL behaviour of sands from various geological contexts in Brazil. They show that the coarse (approx. 100-200μm) quartz fraction of coastal and intra continental, eolian and fluvial-type deposits, might be datable by TL from the upper Holocene to at least the basis of the upper Pleistocene, with a precision of + - 10-15%. (Author)

  1. Thermoluminescence dating of pleistocene sediments

    After a short introduction on recent trends in quaternary geochronology, this article focuses on the thermoluminescence (TL) dating of sediments, whose principles, present limits and prospects are discussed. Results are presented for TL behavior of sands from various geological contexts in Brazil. They show that the coarse (approx. 100-200 μm) quartz fraction of coastal and intracontinental, eolian and fluvial - type deposits, might be datable by TL from the upper Holocene to at least the base of the upper Pleistocene, with a precision of +- 10-15%. (Author)

  2. Size variation in Middle Pleistocene humans.

    Arsuaga, J L; Carretero, J M; Lorenzo, C; Gracia, A; Martínez, I; Bermúdez de Castro, J M; Carbonell, E

    1997-08-22

    It has been suggested that European Middle Pleistocene humans, Neandertals, and prehistoric modern humans had a greater sexual dimorphism than modern humans. Analysis of body size variation and cranial capacity variation in the large sample from the Sima de los Huesos site in Spain showed instead that the sexual dimorphism is comparable in Middle Pleistocene and modern populations. PMID:9262474

  3. Sedimentary environment, diagenesis and sequence stratigraphy of Sarvak Formation in Abteymour Oilfield in Western part of the Dezful embayment

    H., Mehrabi,; H., Rahimpour-Bonab,; M., Omidvar,; H., Hajimashhadi,

    2012-01-01

    Sarvak Formation (Late Albian-Middle Turonian) is one of the important reservoir units after Asmari (Oligo-Miocene) in southwest Iran that host an important hydrocarbon reserves in this region. Due to facies and environmental variations as well as complex diagenetic history, its reservoir properties show intense complexity and heterogeneity. To understand these imposed heterogeneities a comprehensive reservoir study including facies analysis, diagenetic study and sequence stratigraphy are car...

  4. The stratigraphy of cretaceous mudstones in the eastern Fuegian Andes: new data from body and trace fossils

    Olivero, Eduardo B.; Francisco A. Medina; María I. López C.

    2009-01-01

    The stratigraphy of Cretaceous marine mudstones in the Fuegian Andes, roughly equivalent to Charles Darwin's clay-slate formation, remains a still unsolved problem. Previous records of Albian, Turonian-Coniacian, and Santonian-Campanian bivalves are combined with new findings of the Late Albian inoceramid Inoceramus anglicus Woods, and the Maastrichtian ammonites Diplomoceras sp., Anagaudryceras sp., Maorites densicostatus (Kilian and Reboul), Maorites sp., and Pachydiscus (Neodesmoceras) sp....

  5. Contribution to the stratigraphy of the onshore Paraíba Basin, Brazil

    Dilce F. Rossetti

    2012-06-01

    Full Text Available Several publications have contributed to improve the stratigraphy of the Paraíba Basin in northeastern Brazil. However, the characterization and distribution of sedimentary units in onshore areas of this basin are still incomplete, despite their significance for reconstructing the tectono-sedimentary evolution of the South American passive margin. This work provides new information to differentiate among lithologically similar strata, otherwise entirely unrelated in time. This approach included morphological, sedimentological and stratigraphic descriptions based on surface and sub-surface data integrated with remote sensing, optically stimulated luminescence dating, U+Th/He dating of weathered goethite, and heavy mineral analysis. Based on this study, it was possible to show that Cretaceous units are constrained to the eastern part of the onshore Paraíba Basin. Except for a few outcrops of carbonatic rocks nearby the modern coastline, deposits of this age are not exposed to the surface in the study area. Instead, the sedimentary cover throughout the basin is constituted by mineralogically and chronologically distinctive deposits, inserted in the Barreiras Formation and mostly in the Post-Barreiras Sediments, of early/middle Miocene and Late Pleistocene-Holocene ages, respectively. The data presented in this work support tectonic deformation as a factor of great relevance to the distribution of the sedimentary units of the Paraíba Basin.Várias publicações têm contribuído para melhorar a estratigrafia da Bacia Paraíba no nordeste do Brasil. Entretanto, a caracterização e distribuição das unidades sedimentares em áreas continentais desta bacia são ainda incompletas, apesar de sua importância para reconstruir a evolução tectono-sedimentar da margem passiva sulamericana. Este trabalho fornece novas informações para diferenciar entre estratos litologicamente similares que, por outro lado, não são relacionados no tempo. Esta

  6. Oleistocene mammals in the late-early Holocene in Santa Lucia river basin (Uruguay southern)

    This work is about the fossileferous outcrops belongs to the late Pleistocene - early Holocene in Santa Lucia River. It enable to analyse the last records of megafauna vertebrate extinctions (olistecene mammals) with the climate conditions / environment

  7. Latest Early Pleistocene remains of Lynx pardinus (Carnivora, Felidae) from the Iberian Peninsula: Taxonomy and evolutionary implications

    Boscaini, Alberto; Alba, David M.; Beltrán, Juan F.; Moyà-Solà, Salvador; Madurell-Malapeira, Joan

    2016-07-01

    The Iberian lynx (Lynx pardinus) is a critically endangered felid that, during the last fifty years, has been subject to an intensive conservation program in an attempt to save it from extinction. This species is first recorded at ca. 1.7-1.6 Ma (late Villafranchian, late Early Pleistocene) in NE Iberian Peninsula, roughly coinciding with the large faunal turnover that occurred around the middle to late Villafranchian boundary. Here we describe the largest collection of L. pardinus remains available to date from the Iberian late Early Pleistocene (Epivillafranchian), including localities from the Vallparadís Section (Vallès-Penedès Basin, NE Iberian Peninsula) and Cueva Victoria (Cartagena, SE Iberian Peninsula). The morphology and biometry of the studied material attests to the widespread occurrence of L. pardinus in the Mediterranean coast of the Iberian Peninsula since the latest Early Pleistocene, i.e., about 0.5 million years earlier than it was generally accepted (i.e., at the beginning of the Middle Pleistocene). Based on the features observed in the large sample studied in this paper, we conclude that Lynx spelaeus is a junior synonym of L. pardinus and further propose to assign all the Epivillafranchian and younger fossil lynxes from SW Europe to the extant species L. pardinus. Due to the arrival of the Eurasian lynx (Lynx lynx) into Europe at the beginning of the Late Pleistocene, the attribution of specimens younger than MIS 5e to either this species or L. pardinus solely on morphological grounds has proven equivocal. Here we discuss the main diagnostic features of both species of European lynxes and further review their evolutionary history and paleobiogeography throughout the Pleistocene.

  8. Cenozoic sequence stratigraphy in the eastern North Sea

    Michelsen, O.; Thomsen, E.; Danielsen, M.; Heilmann-Clausen, C.; Jordt, H.; Laursen, G.V.

    1995-05-01

    The Cenozoic evolution of the epicontinental North Sea Basin is described on the basis of sequence stratigraphy, comprising analyses of seismic sections, petrophysical logs, and biostratigraphic studies of foraminifera, dinoflagellates, and calcareous nannofossils. Stratigraphic, palaeogeographic, and palaeoecological information from the Danish onshore area is integrated in the study. The deposits are subdivided into 21 sequences, which groups into seven informal major units. The sequence boundaries are identified by differences in seismic facies and by seismic onlap, toplap, and truncation features. The maximum flooding surface is placed at an internal downlap surface which correlates with high values on the gamma ray log. The source of sediments and the direction of sediment transport changed several times during the Cenozoic. Transport was mainly from the north during the Late Paleocene and Early Eocene, from the west during the Middle and Late Eocene, and from the north and northwest during the Oligocene to quaternary. The depocenters of the seven major units are generally located marginally, probably adjoining the source areas. There is only minor evidence for changes in subsidence rates in the basin. A constant rate is assumed from the Paleocene to the mid Middle Miocene. For the remaining part of the Cenozoic and increased rate is indicated. A tentative relative sea-level curve for the North Sea Basin is proposed. The overall trends of the curve are broadly comparable with the global sea-level curve of Haq et al. Discrepancies may be caused by differences in the biostratigraphic calibrations. The most pronounced Oligocene sea-level fall is dated ot the latest Oligocene. (au) (83 refs.)

  9. A Pleistocene lacustrine episode in southeastern Libya

    Results of an investigation of the Th/U dating and isotopic (stable carbon and oxygen) palaeohydrology of the fossiliferous lacustrine deposits of middle Pleistocene age found in Central Fezzan (Libya) are reported. (U.K.)

  10. Magnetic iron-nickel sulphides in the Pliocene and Pleistocene marine marls from the Vrica section (Calabria, Italy)

    Velzen, A.J. van; Dekkers, M.J.; Zijderveld, J.D.A.

    1993-01-01

    The rock magnetic properties of the late Pliocene and early Pleistocene open-marine marls from the Vrica section in Calabria (Italy) point to magnetic sulphide as the main magnetic mineral and remanence carrier. The maximum blocking temperatures, however, are between 340 and 360°C, which is too high

  11. Lower Pleistocene hominids and artifacts from Atapuerca-TD6 (Spain)

    Carbonell, E; Bermúdez de Castro, J M; Arsuaga, J L; Díez, J C; Rosas, A; Cuenca-Bescós, G; Sala, R; Mosquera, M; Rodríguez, X P

    1995-08-11

    Human remains dating to more than 780,000 years ago are associated with a rich faunal and lithic assemblage in the Pleistocene cave site of Gran Dolina (TD), Sierra de Atapuerca, Burgos, Spain. The micromammal species represent the late Biharian (Mimomys savini zone), and the lithic objects represent pre-Acheulean technology (Mode 1) and comes from the TD6 level below the Matuyama-Brunhes boundary. The Gran Dolina hominid fossils cannot be comfortably accommodated in any of the defined Homo species. They could be considered a primitive form of Homo heidelbergensis, but a new species might be named in the future if the sample is enlarged. The new human fossil evidence demonstrates that Western Europe was settled at least since the late early Pleistocene. PMID:7638598

  12. Lethal Interpersonal Violence in the Middle Pleistocene

    Nohemi Sala; Juan Luis Arsuaga; Ana Pantoja-Pérez; Adrián Pablos; Ignacio Martínez; Quam, Rolf M.; Asier Gómez-Olivencia; José María Bermúdez de Castro; Eudald Carbonell

    2015-01-01

    Evidence of interpersonal violence has been documented previously in Pleistocene members of the genus Homo, but only very rarely has this been posited as the possible manner of death. Here we report the earliest evidence of lethal interpersonal violence in the hominin fossil record. Cranium 17 recovered from the Sima de los Huesos Middle Pleistocene site shows two clear perimortem depression fractures on the frontal bone, interpreted as being produced by two episodes of localized blunt force ...

  13. Evolution, Systematics, and Phylogeography of Pleistocene Horses in the New World: A Molecular Perspective

    Weinstock, Jaco; Willerslev, Eske; Sher, A.;

    2005-01-01

    . Furthermore, we show that stilt-legged horses, commonly regarded as Old World migrants related to the hemionid asses of Asia, were in fact an endemic North American lineage. Finally, our data suggest that there were fewer horse species in late Pleistocene North America than have been named on morphological...... grounds. Both caballine and stilt-legged lineages may each have comprised a single, wide-ranging species....

  14. The Murray Springs Clovis site, Pleistocene extinction, and the question of extraterrestrial impact

    Haynes, C. Vance; Boerner, J.; Domanik, K.; Lauretta, D.; Ballenger, J.; Goreva, J.

    2010-01-01

    Some of the evidence for the recent hypothesis of an extraterrestrial impact that caused late Pleistocene megafaunal extinctions [Firestone et al. (2007) Proc Natl Acad Sci USA 104:16016–16021] was based upon samples collected at Murray Springs, a Clovis archaeological site in southeastern Arizona. Here we describe sampling and analyses of magnetic separates from within, above, and below the lower Younger Dryas boundary (LYDB) black mat at Murray Springs, as well as radiation measurements fro...

  15. Polygenetic development and paleoenvironmental implications of a Pleistocene calcrete at Tongoy, central northern Chile.

    M. Pfeiffer; J. Le Roux; H. Kemnitz

    2011-01-01

    The Norte Chico Region, in central northern Chile, is a particularly sensitive area to Quaternary climate changes because of its extreme climatic gradients. However, very little has been done to determine the late Pleistocene climatic conditions of the area. Calcretes are known to be important repositories of information on past ecosystems and environments. In the Tongoy paleobay, a series of four marine beach terraces have developed over a Mio-Pliocene calcareous formation since MIS 11 to th...

  16. Upper Cretaceous to Pleistocene melilitic volcanic rocks of the Bohemian Massif: petrology and mineral chemistry

    Skála Roman

    2015-06-01

    Full Text Available Upper Cretaceous to Pleistocene volcanic rocks of the Bohemian Massif represent the easternmost part of the Central European Volcanic Province. These alkaline volcanic series include rare melilitic rocks occurring as dykes, sills, scoria cones and flows. They occur in three volcanic periods: (i the Late Cretaceous to Paleocene period (80–59 Ma in northern Bohemia including adjacent territories of Saxony and Lusatia, (ii the Mid Eocene to Late Miocene (32.3–5.9 Ma period disseminated in the Ohře Rift, the Cheb–Domažlice Graben, Vogtland, and Silesia and (iii the Early to Late Pleistocene period (1.0–0.26 Ma in western Bohemia. Melilitic magmas of the Eocene to Miocene and Pleistocene periods show a primitive mantle source [(143Nd/144Ndt=0.51280–0.51287; (87Sr/86Srt=0.7034–0.7038] while those of the Upper Cretaceous to Paleocene period display a broad scatter of Sr–Nd ratios. The (143Nd/144Ndt ratios (0.51272–0.51282 of the Upper Cretaceous to Paleocene rocks suggest a partly heterogeneous mantle source, and their (87Sr/86Srt ratios (0.7033–0.7049 point to an additional late- to post-magmatic hydrothermal contribution. Major rock-forming minerals include forsterite, diopside, melilite, nepheline, sodalite group minerals, phlogopite, Cr- and Ti-bearing spinels. Crystallization pressures and temperatures of clinopyroxene vary widely between ~1 to 2 GPa and between 1000 to 1200 °C, respectively. Nepheline crystallized at about 500 to 770 °C. Geochemical and isotopic similarities of these rocks occurring from the Upper Cretaceous to Pleistocene suggest that they had similar mantle sources and similar processes of magma development by partial melting of a heterogeneous carbonatized mantle source.

  17. 'Combined reflectance stratigraphy' - subdivision of loess successions by diffuse reflectance spectrometry (DRS)

    Szeberényi, Jozsef; Bradak-Hayashi, Balázs; Kiss, Klaudia; Kovács, József; Varga, György; Balázs, Réka; Szalai, Zoltán; Viczián, István

    2016-04-01

    The different varieties of loess (and intercalated paleosol layers) together constitute one of the most widespread terrestrial sediments, which was deposited, altered, and redeposited in the course of the changing climatic conditions of the Pleistocene. To reveal more information about Pleistocene climate cycles and/or environments the detailed lithostratigraphical subdivision and classification of the loess variations and paleosols are necessary. Beside the numerous method such as various field measurements, semi-quantitative tests and laboratory investigations, diffuse reflectance spectroscopy (DRS) is one of the well applied method on loess/paleosol sequences. Generally, DRS has been used to separate the detrital and pedogenic mineral component of the loess sections by the hematite/goethite ratio. DRS also has been applied as a joint method of various environmental magnetic investigations such as magnetic susceptibility- and isothermal remanent magnetization measurements. In our study the so-called "combined reflectance stratigraphy method" were developed. At First, complex mathematical method was applied to compare the results of the spectral reflectance measurements. One of the most preferred multivariate methods is cluster analysis. Its scope is to group and compare the loess variations and paleosol based on the similarity and common properties of their reflectance curves. In the Second, beside the basic subdivision of the profiles by the different reflectance curves of the layers, the most characteristic wavelength section of the reflectance curve was determined. This sections played the most important role during the classification of the different materials of the section. The reflectance value of individual samples, belonged to the characteristic wavelength were depicted in the function of depth and well correlated with other proxies like grain size distribution and magnetic susceptibility data. The results of the correlation showed the significance of

  18. Late-glacial and Holocene Vegetation and Climate Variability, Including Major Droughts, in the Sky Lakes Region of Southeastern New York State

    Menking, Kirsten M.; Peteet, Dorothy M.; Anderson, Roger Y.

    2012-01-01

    Sediment cores from Lakes Minnewaska and Mohonk in the Shawangunk Mountains of southeastern New York were analyzed for pollen, plantmacrofossils, macroscopic charcoal, organic carbon content, carbon isotopic composition, carbon/nitrogen ratio, and lithologic changes to determine the vegetation and landscape history of the greater Catskill Mountain region since deglaciation. Pollen stratigraphy generally matches the New England pollen zones identified by Deevey (1939) and Davis (1969), with boreal genera (Picea, Abies) present during the late Pleistocene yielding to a mixed Pinus, Quercus and Tsuga forest in the early Holocene. Lake Minnewaska sediments record the Younger Dryas and possibly the 8.2 cal kyr BP climatic events in pollen and sediment chemistry along with an 1400 cal yr interval of wet conditions (increasing Tsuga and declining Quercus) centered about 6400 cal yr BP. BothMinnewaska andMohonk reveal a protracted drought interval in themiddle Holocene, 5700-4100 cal yr BP, during which Pinus rigida colonized the watershed, lake levels fell, and frequent fires led to enhanced hillslope erosion. Together, the records show at least three wet-dry cycles throughout the Holocene and both similarities and differences to climate records in New England and central New York. Drought intervals raise concerns for water resources in the New York City metropolitan area and may reflect a combination of enhanced La Niña, negative phase NAO, and positive phase PNA climatic patterns and/or northward shifts of storm tracks.

  19. Strontium isotope stratigraphy of the Pelotas Basin

    Strontium isotope data were obtained from foraminifera shells of the Pelotas Basin Tertiary deposits to facilitate the refinement of the chronostratigraphic framework of this section. This represents the first approach to the acquisition of numerical ages for these strata. Strontium isotope stratigraphy allowed the identification of eight depositional hiatuses in the Eocene-Pliocene section, here classified as disconformities and a condensed section. The reconnaissance of depositional gaps based on confident age assignments represents an important advance considering the remarkably low chronostratigraphic resolution in the Cenozoic section of the Pelotas Basin. The recognition of hiatuses that match hiatuses is based on biostratigraphic data, as well as on global events. Furthermore, a substantial increase in the sedimentation rate of the upper Miocene section was identified. Paleotemperature and productivity trends were identified based on oxygen and carbon isotope data from the Oligocene-Miocene section, which are coherent with worldwide events, indicating the environmental conditions during sedimentation. (author)

  20. Strontium isotope stratigraphy of the Pelotas Basin

    Zerfass, Geise de Santana dos Anjos, E-mail: geise.zerfass@petrobras.com.br [Petroleo Brasileiro S.A. (PETROBRAS/CENPES/PDGEO/BPA), Rio de Janeiro, RJ (Brazil). Centro de Pesquisas e Desenvolvimento Leopoldo Americo Miguez de Mello; Chemale Junior, Farid, E-mail: fchemale@unb.br [Universidade de Brasilia (UnB), DF (Brazil). Instituto de Geociencias; Moura, Candido Augusto Veloso, E-mail: candido@ufpa.br [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Centro de Geociencias. Dept. de Geoquimica e Petrologia; Costa, Karen Badaraco, E-mail: karen.costa@usp.br [Instituto Oceanografico, Sao Paulo, SP (Brazil); Kawashita, Koji, E-mail: koji@usp.br [Unversidade de Sao Paulo (USP), SP (Brazil). Centro de Pesquisas Geocronologicas

    2014-07-01

    Strontium isotope data were obtained from foraminifera shells of the Pelotas Basin Tertiary deposits to facilitate the refinement of the chronostratigraphic framework of this section. This represents the first approach to the acquisition of numerical ages for these strata. Strontium isotope stratigraphy allowed the identification of eight depositional hiatuses in the Eocene-Pliocene section, here classified as disconformities and a condensed section. The reconnaissance of depositional gaps based on confident age assignments represents an important advance considering the remarkably low chronostratigraphic resolution in the Cenozoic section of the Pelotas Basin. The recognition of hiatuses that match hiatuses is based on biostratigraphic data, as well as on global events. Furthermore, a substantial increase in the sedimentation rate of the upper Miocene section was identified. Paleotemperature and productivity trends were identified based on oxygen and carbon isotope data from the Oligocene-Miocene section, which are coherent with worldwide events, indicating the environmental conditions during sedimentation. (author)

  1. Evidence against a Pleistocene desert refugium in the Lower Colorado River Basin

    Holmgren, Camille A.; Betancourt, Julio L.; Peñalba, M. Cristina; Delgadillo, José; Zuravnsky, Kristin; Hunter, Kimberly L.; Rylander, Kate A.; Weiss, Jeremy L.

    2014-01-01

    Aim The absence of Sonoran Desert plants in late Pleistocene-aged packrat middens has led to speculation that they survived glacial episodes either in refugia as intact associations (Clementsian community concept) or in dry microsites within chaparral or woodland according to individualistic species responses (Gleasonian community concept). To test these hypotheses, we developed a midden record from one likely refugium in north-eastern Baja California, Mexico. We also measured stomatal guard cell size in fossil leaves to further evaluate site-level individualistic responses of Larrea tridentata (creosote bush) ploidy races to climatic changes, including monsoonal history, over the late Quaternary.

  2. Human talus bones from the Middle Pleistocene site of Sima de los Huesos (Sierra de Atapuerca, Burgos, Spain).

    Pablos, Adrián; Martínez, Ignacio; Lorenzo, Carlos; Gracia, Ana; Sala, Nohemi; Arsuaga, Juan Luis

    2013-07-01

    Here we present and describe comparatively 25 talus bones from the Middle Pleistocene site of the Sima de los Huesos (SH) (Sierra de Atapuerca, Burgos, Spain). These tali belong to 14 individuals (11 adult and three immature). Although variation among Middle and Late Pleistocene tali tends to be subtle, this study has identified unique morphological characteristics of the SH tali. They are vertically shorter than those of Late Pleistocene Homo sapiens, and show a shorter head and a broader lateral malleolar facet than all of the samples. Moreover, a few shared characters with Neanderthals are consistent with the hypothesis that the SH population and Neanderthals are sister groups. These shared characters are a broad lateral malleolar facet, a trochlear height intermediate between modern humans and Late Pleistocene H. sapiens, and a short middle calcaneal facet. It has been possible to propose sex assignment for the SH tali based on their size. Stature estimates based on these fossils give a mean stature of 174.4 cm for males and 161.9 cm for females, similar to that obtained based on the long bones from this same site. PMID:23706407

  3. Early Pleistocene climate in western arid central Asia inferred from loess-palaeosol sequences

    Wang, Xin; Wei, Haitao; Taheri, Mehdi; Khormali, Farhad; Danukalova, Guzel; Chen, Fahu

    2016-02-01

    Arid central Asia (ACA) is one of the most arid regions in the mid-latitudes and one of the main potential dust sources for the northern hemisphere. The lack of in situ early Pleistocene loess/dust records from ACA hinders our comprehensive understanding of the spatio-temporal record of aeolian loess accumulation and long term climatic changes in Asia as a whole. Here, we report the results of sedimentological, chronological and climatic studies of early Pleistocene loess-palaeosol sequences (LPS) from the northeastern Iranian Golestan Province (NIGP) in the western part of ACA. Our results reveal that: 1) Accumulation of loess on the NIGP commenced at ~2.4-1.8 Ma, making it the oldest loess known so far in western ACA; 2) the climate during the early Pleistocene in the NIGP was semi-arid, but wetter, warmer, and less windy than during the late Pleistocene and present interglacial; 3) orbital-scale palaeoclimatic changes in ACA during the early Pleistoceneare in-phase with those of monsoonal Asia, a relationship which was probably related to the growth and decay of northern hemisphere ice sheets.

  4. Cretaceous stratigraphy of sierra de Beauvoir, Fuegian Andes, Argentina

    Daniel R. Martinioni

    2013-03-01

    Full Text Available The Cretaceous stratigraphy north of Lago Fagnano, Tierra del Fuego, was poorly known until the last decade of the twentieth century. Stratigraphic, sedimentologic, and paleontological observations in sierra de Beauvoir and surroundings enabled the recognition of two main packages of dominant marine mudstone. 1 A more than 450 m thick package of slate, shale and mudstone, constituted by the revised Lower Cretaceous Beauvoir Formation. A type locality in the core of sierra de Beauvoir, with diagnostic Aptian-Albian fossils including inoceramids of the Inoceramus neocomiensis group and Aucellina sp., is proposed for this unit. 2 A more than 1,500 m thick, mudstone-dominated, but sandier upward, package consisting of at least three Upper Cretaceous units. Arroyo Castorera Formation (nom. nov. bears Turonian inoceramids of the I. hobetsensis group and I. cf. lamarcki. Río Rodríguez Formation (nom. nov. has Coniacian inoceramids, cf. Cremnoceramus sp. Policarpo Formation bears poorly preserved ammonites (Grossouvrites sp., Maorites sp., and Diplomoceras sp., together with diagnostic Maastrichtian dinocysts (Manumiella spp. complex, Operculodinium cf. azcaratei, some specimens of Fibrocysta-Exochosphaeridium complex, and Palaeocystodinium granulatum. Both packages were deposited in deep-marine environments and show, as a whole, a coarsening upward trend in the succession of Cretaceous rocks. Beauvoir Formation is part of the back-arc basin-fill of the former Rocas Verdes marginal basin. Arroyo Castorera Formation appears as a transition to the initiating Late Cretaceous Austral foreland basin evolution, clearly represented by turbiditic deposits of Río Rodríguez and Policarpo formations that were progressively accumulated in front of the rising Fuegian Andes.

  5. Plio-Pleistocene evolution of Bohai Basin (East Asia): demise of Bohai Paleolake and transition to marine environment

    Yi, Liang; Deng, Chenglong; Tian, Lizhu; Xu, Xingyong; Jiang, Xingyu; Qiang, Xiaoke; Qin, Huafeng; Ge, Junyi; Chen, Guangquan; Su, Qiao; Chen, Yanping; Shi, Xuefa; Xie, Qiang; Yu, Hongjun; Zhu, Rixiang

    2016-01-01

    The Bohai Basin was transformed to an inner shelf sea hundreds of thousands years ago. This youngest land-sea transition participated in the significant modification of the distribution of fresh water, sediment fluxes and climate in East Asia, and played an important role in the origin of the Asian marginal seas. Here we present the results of a magnetostratigraphic investigation and propose a conceptual model for the land-sea transition. Our findings indicate that the transition probably started several million years ago, from a fluvial system during the late Miocene and early Pliocene, to a lacustrine environment between the late Pliocene and Middle Pleistocene, and finally to a marine system in the late Pleistocene. Comparison of our results with previous research suggests that the Bohai Paleolake was initiated from the late Pliocene, was fully developed prior to ~1.0 Ma, and terminated around the late Middle Pleistocene. The Miaodao Islands formed the eastern “barrier” of the basin and since the Pliocene or earlier they played a significant role in blocking the lake water and sediments. They deformed from ~1.0 Ma, subsided significantly at ~0.3 Ma and completely by ~0.1 Ma, resulting in the maturation of the basin as an inner shelf sea. PMID:27384419

  6. Eocene to Pleistocene lithostratigraphy, chronostratigraphy and tectono-sedimentary evolution of the Calama Basin, northern Chile Litoestratigrafía, cronoestratigrafía durante el Eoceno al Pleistoceno y evolución tectono-sedimentaria de la Cuenca de Calama, norte de Chile

    Geoffrey May; Adrian J Hartley; Guillermo Chong; Fin Stuart; Peter Turner; Stephanie J Kape

    2005-01-01

    New 40Ar/39Ar radiometric, sedimentological and structural data from post-Paleocene sedimentary strata in the Calama Basin, northern Chile suggest that the established lithostratigraphy of the basin-fill requires revision. A new lithostratigraphic scheme for the Eocene-Pleistocene stratigraphy of the Calama Basin is proposed here. The key features of this scheme are that the existing Calama Formation is retained although the age of the formation is redefined as (?Lower) Eocene to (?)Lower Mio...

  7. Cambios en lagos y circulación fluvial vinculados al calentamiento climático del Pleistoceno tardío-Holoceno temprano en Patagonia e isla 25 de mayo, islas Shetland del Sur, Antártida Changes in lakes and fluvial circulationlinked to climate warming in Late Pleistocene - Early Holocene in Patagonia and 25 de Mayo Island, Shetland del Sur Islands, Antarctica

    R.A. del Valle

    2007-12-01

    Full Text Available El calentamiento clim ático que afectó a la Patagonia en el Pleistoceno tardío-Holoceno temprano produjo cambios en la morfología del paisaje, incluyendo la génesis, desarrollo y desintegración de grandes lagos al este de los Andes. Hasta entonces, los glaciares y sus morenas formaban diques naturales que embalsaron las aguas de deshielo y mantenían alto el nivel de las aguas en los grandes paleolagos. Posteriormente, la migración hacia el sur de la mejoría climática ocasionó la progresiva fusión del campo de hielo regional, y las morenas fueron cortadas por la erosión fluvial, cuando el calentamiento climático impactó plenamente en la región. El proceso afectó a la región de norte a sur en tiempos diferentes: 1 hace c. 13.200 años en el norte, 2 durante la transición Pleistoceno/Holoceno en la parte central, y 3 finalmente, en Tierra del Fuego hace unos 7.800 años. El rápido retroceso de los glaciares produjo el desalojo de los valles andinos a ambos lados de la cordillera, lo cual abrió cauces fluviales que atraviesan la cordillera desde entonces, inaugurando el drenaje hacia el océano Pacífico de grandes lagos glaciales que existían al oriente de los Andes. Esto resultó en el rápido descenso del nivel de los paleolagos. Un proceso similar ocurrió en las islas Shetland del Sur (Antártida hace unos 6.000 años.The climate warming that affected Patagonia region during late Pleistocene-early Holocene times produced changes in landscape morphology, including the formation, development, breakdown and disintegration of big lakes at the eastern side of Andes. Before these times, glaciers and their moraines formed natural dams that maintained a high water level in large paleolakes. The subsequent southward migration of climate amelioration produced the melting of the regional ice field, and moraines were cut by fluvial erosion, when climate warming strongly impacted in the region. The process occurred in the region from

  8. Changing depositional environments during the Late Quatrnary along the western continental margin of India

    Thamban, M.

    variations on a shallow core off Cochin, suggests that the average sedimentation rates were very high (~6 13.2 cm/kyr) and varied widely during the Holocene and the late Pleistocene. Grain size measurements reveal that the clay content varied with the Late...

  9. Logging Data High-Resolution Sequence Stratigraphy

    Li Hongqi; Xie Yinfu; Sun Zhongchun; Luo Xingping

    2006-01-01

    The recognition and contrast of bed sets in parasequence is difficult in terrestrial basin high-resolution sequence stratigraphy. This study puts forward new methods for the boundary identification and contrast of bed sets on the basis of manifold logging data. The formation of calcareous interbeds, shale resistivity differences and the relation of reservoir resistivity to altitude are considered on the basis of log curve morphological characteristics, core observation, cast thin section, X-ray diffraction and scanning electron microscopy. The results show that the thickness of calcareous interbeds is between 0.5 m and 2 m, increasing on weathering crusts and faults. Calcareous interbeds occur at the bottom of Reservoir resistivity increases with altitude. Calcareous interbeds may be a symbol of recognition for the boundary of bed sets and isochronous contrast bed sets, and shale resistivity differences may confirm the stack relation and connectivity of bed sets. Based on this, a high-rcsolution chronostratigraphic framework of Xi-1 segment in Shinan area, Junggar basin is presented, and the connectivity of bed sets and oil-water contact is confirmed. In this chronostratigraphic framework, the growth order, stack mode and space shape of bed sets are qualitatively and quantitatively described.

  10. Geometric morphometric analysis of the early Pleistocene hominin teeth from Jianshi,Hubei Province,China

    Ronald; CLARKE

    2010-01-01

    Although the early Pleistocene hominin fossils found in East Asia continent are widely recognized as the earliest hominins migrated from Africa, debates remain on the morphology and taxonomy of these fossils. In this study, dental crown shape of the three early Pleistocene hominin teeth (P3, M1, and M1) found in Jianshi, Hubei Province of China was analyzed by means of geometric morphometrics. The comparative samples of fossil hominins from Africa, Asia, and Europe as well as those of modern humans (N=257) were used. The results indicate that the contour, asymmetry, and cusp patterns of these three types of teeth differ obviously between the fossil hominins and modern humans. The crown shape of P3 in most fossil hominins including Australopithecus, African early Homo, and Asian Pleistocene hominins are asymmetric with their crown occlusal contours long and curving elliptic-shaped. The occlusal contour of the fossil hominin M1 is symmetric and rectangle-shaped with no marked cusp protrusion. The crown shape of fossil M1 is characterized by asymmetric contour with slightly projected metaconid and hypoconid. On the contrary, in modern Chinese and some European late Pleistocene hominins, the crowns of P3s show symmetric contours with buccal side wider than lingual side; the crown shape of M1 is asymmetric with lingual cusp distalplaced, especially for hypoconid; the M1 has symmetric and round crown contour. Our study reveals that Australopithecus has wide variations in its crown shape, whereas these dental morphospaces of Asian hominins are closely placed. The crown contour, symmetry, and cusp patterns of these three teeth of Jianshi hominin resemble those of Asian early and middle Pleistocene hominins. No marked difference in dental crown shape is shown between the Jianshi hominin and other Chinese Homo erectus, and there is also no evidence in support of the Jianshi hominin’s closeness to Australopithecus and African early Homo members.

  11. Late Triassic - Early Jurassic successions of the Atuel depocenter: sequence stratigraphy and tectonic controls Sucesiones del Triásico Tardío - Jurásico Temprano del depocentro Atuel: estratigrafía secuencial y controles tectónicos

    Silvia Lanés

    2008-12-01

    Full Text Available Biostratigraphic correlations of the Late Triassic - Early Jurassic successions of the Atuel depocenter allowed determining the accommodation changes and the possible tectonic controls on sedimentation. The Rhaetian - late Early Sinemurian deposits contain facies of slope-type fan deltas, braided fluvial systems and low sinuosity rivers with alternate bars deposited during a synrift phase. The late Early Sinemurian - Toarcian series host facies of intermediate (Gilbert to shelf type fan deltas, braided and low sinuosity fluvial systems, wave-dominated estuaries, transgressive storm-dominated and turbidite-influenced marine shelves which record the sag phase. According to different criteria two stratigraphic schemes are proposed, the first one considering tectosedimentary units (TSU and the second one using "Exxon-like" sequences. In the first scheme the synrift TSU matches the actual Precuyo Mesosequence and the sag TSU is partly equivalent to the Cuyo Mesosequence, mainly keeping the current mesosequence scheme for the Neuquén basin but assigning the fandeltaic deposits to the Precuyo Mesosequence. The second sequence scheme considers the whole Late Triassic - Early Jurassic succession as a part of the Cuyo Mesosequence, where the synrift deposits composes the detached lowstand system tract (LST and most of the sag deposits makes the transgressive system tract (TST. The basal sequence boundary does not crop out, the flooding surface at the TST base and the maximum flooding surface at the TST top are respectively marked by the lowest estuarine levels and by black shales with suboxic-compatible bivalves (Bositra sp..La correlación bioestratigráfica de las sucesiones del Triásico Tardío - Jurásico Temprano del depocentro Atuel permitió determinar los cambios del espacio de acomodación y los posibles controles tectónicos de la sedimentación. La sección del Retiano - Sinemuriano Temprano tardío contiene facies de abanicos deltaicos de

  12. Controls on aggradation and incision in the NE Negev, Israel, since the middle Pleistocene

    Matmon, A.; Elfassi, S.; Hidy, A.; Geller, Y.; Porat, N.

    2016-05-01

    We investigated the mid-Pleistocene to recent aggradation-incision pattern of two drainage systems (Nahal Peres and Nahal Tahmas) in the hyperarid north eastern Negev desert, southern Israel. Although these drainage systems drain into the tectonically active Dead Sea basin, lake level fluctuations cannot account for the aggradation-incision pattern as bedrock knickpoints disconnect the investigated parts of these drainage systems from base level influence. We applied geomorphic mapping, soil stratigraphy, optically stimulated luminescence (OSL) and cosmogenic (in situ 10Be) exposure dating to reconstruct cycles of aggradation and incision of alluvial terraces and to study their temporal association with regional periods of humidity and aridity and global glacial-interglacial cycles. The spatial and temporal relationships between the alluvial units suggest changes in the drainage system behavior since the middle Pleistocene, and show a pattern in which prolonged periods of sediment aggradation alternated with short periods of rapid and intense degradation through erosion and incision into sediment and bedrock. We obtain ages for several Pleistocene-Holocene periods of incision: ~ 1.1 Ma, ~ 300 ka, ~ 120 ka, ~ 20 ka, ~ 12 ka and ~ 2 ka. Although broadly synchronous, the Nahal Peres and Nahal Tahmas systems exhibit temporal differences in aggradation and incision. Hyperarid conditions have persisted in the region at least since the middle Pleistocene, as evidenced by gypsic-salic soils that ubiquitously cap the investigated alluvial terraces. This observation is consistent with other observations throughout the Negev indicating prolonged aridity. Thus, alternation between sediment aggradation and degradation cannot be correlated in a simple and straightforward way to climatic changes. We explain the temporal differences in aggradation and incision between Nahal Peres and Nahal Tahmas as resulting from the differences in stream gradient, basin hypsometry, and drainage

  13. Middle Pleistocene infill of Tibetan Plateau margin rivers, Zanskar, India

    Munack, Henry; Blöthe, Jan; Korup, Oliver; Fülöp, Réka-Hajnalka; Codilean, Alexandru T.; Fink, David

    2015-04-01

    The Indus, one of Asia's premier rivers, drains the NW Himalaya and the Transhimalayan ranges that fringe the western Tibetan Plateau margin. There, upstream of the western Himalayan syntaxis, river valleys alternate between deeply incised bedrock gorges and broad alluviated reaches, while average denudation rates decrease by an order of magnitude towards the Tibetan Plateau margin to rates of ~10 mm ka-1. Vast fill terrace staircases, the highest of them located up to 400 m above current river level, and intercalated lake sediments indicate alternating phases of incision and aggradation within the region, underlining the high landform preservation potential in the rain shadow of the High Himalaya. However, despite a broad interest in a better understanding of mechanisms that modulate plateau erosion, age constraints on the generation of these impressive features are sparse, though indicate mainly Pleistocene formation ages. We present new age constraints from the More Plains section in the headwaters of the Zanskar River, a major tributary to the upper Indus. The vast sedimentary successions of the More Plains originally belonged to a former endorheic basin that has been tapped by the Zanskar River, today revealing exposures of >250 m of sedimentary fill that continues to smother a previously dissected alpine headwater landscape. We combine 10Be surface exposure dating and catchment-averaged denudation rates, morphometric analysis and field observation to constrain the late Quaternary history of this section. Analysis of a 10Be depth profile on top of the More Plains, together with the dating of nearby amalgamated surface samples, indicate a surface exposure of ~170 +/- 20 ka such that deposition of this valley fill ceased during a Middle Pleistocene cold stage (MIS 6). Using GIS-based algorithms we estimate that ~3.6 km3 was removed from this section by fluvial erosion, requiring a specific sediment yield of >130 t km-2 yr-1 averaged over the past 170 ka. This

  14. Pleistocene aridification cycles shaped the contemporary genetic architecture of Southern African baboons.

    Riashna Sithaldeen

    Full Text Available Plio-Pleistocene environmental change influenced the evolutionary history of many animal lineages in Africa, highlighting key roles for both climate and tectonics in the evolution of Africa's faunal diversity. Here, we explore diversification in the southern African chacma baboon Papio ursinus sensu lato and reveal a dominant role for increasingly arid landscapes during past glacial cycles in shaping contemporary genetic structure. Recent work on baboons (Papio spp. supports complex lineage structuring with a dominant pulse of diversification occurring 1-2Ma, and yet the link to palaeoenvironmental change remains largely untested. Phylogeographic reconstruction based on mitochondrial DNA sequence data supports a scenario where chacma baboon populations were likely restricted to refugia during periods of regional cooling and drying through the Late Pleistocene. The two lineages of chacma baboon, ursinus and griseipes, are strongly geographically structured, and demographic reconstruction together with spatial analysis of genetic variation point to possible climate-driven isolating events where baboons may have retreated to more optimum conditions during cooler, drier periods. Our analysis highlights a period of continuous population growth beginning in the Middle to Late Pleistocene in both the ursinus and the PG2 griseipes lineages. All three clades identified in the study then enter a state of declining population size (Nef through to the Holocene; this is particularly marked in the last 20,000 years, most likely coincident with the Last Glacial Maximum. The pattern recovered here conforms to expectations based on the dynamic regional climate trends in southern Africa through the Pleistocene and provides further support for complex patterns of diversification in the region's biodiversity.

  15. Pleistocene vegetation change in central Africa recorded off the Congo River

    Dupont, L. M.

    2003-04-01

    Marine sediments from the Congo Canyon accumulate material and information from one of Africa's large inland basins that is covered, at present, mainly with lowland rain forest and swamp forests. The sediments provide a record of monsoon related hydrological and vegetation change. Multiproxy studies were carried out on ODP Site 1075 located north of the undersea canyon, and GeoB Site 1008 located south of the canyon. Pollen records are compared with other terrestrial signals (iron, clay minerals, biomarkers). The differentiated responses of mangroves, grasslands and swamps, lowland rain forest, and Afromontane forest to environmental fluctuations give insight in several aspects of Pleistocene climate cycles. The record of Rhizophora (mangrove tree) pollen is consolidated by biomarker data and shows maxima during interglacial periods and during periods of rapid sea-level rise. While the latter might be the effect of increased erosion of mangrove peat, the first indicates extension of mangrove swamps during periods with increased run-off. The record of lowland forest pollen indicates extension of the rain forest as a response to increased precipitation in periods of strong monsoons of the past 150 ka which is corroborated by clay mineral fluctuations. During the humid periods, Poaceae (grasses) and Cyperaceae pollen percentages are low indicating a closed canopy in large areas of the basin. During interglacial stages of the early Pleistocene, maxima of tropical forest elements combine with maxima of grass and cyperaceous pollen indicating that the warm periods might have been drier than those of the late Pleistocene. Podocarpus pollen percent maxima register extension of the Afromontane forest during cool periods from 1.05 to 0.6 Ma. Restricted distribution of mountainous forest during the late Pleistocene glacial stages (MIS 6, 4-2) is concurrent with extension of open vegetation types indicating more arid conditions in equatorial areas.

  16. Ecospaces occupied by Homo erectus and Homo sapiens in insular Southeast Asia in the Pleistocene

    Hertler, Christine; Haupt, Susanne; Volmer, Rebekka; Bruch, Angela

    2014-05-01

    Hominins migrated to the islands of the Sunda Shelf multiple times. At least two immigration events are evident, an early immigration of Homo erectus in the late Early Pleistocene and a second immigration of Homo sapiens during the Late Pleistocene. Regional environments changed considerably in the Pleistocene. Expansion patterns among hominins are at least co-determined by their ecologies and environmental change. We examine these expansion patterns on the basis of habitat reconstructions. Mammalian communities provide a geographically extensive record and permit to assess hominin ecospaces. Although chronological resolution is low, they represent the most complete record of habitat changes associated with hominin expansion patterns. In order to reconstruct and compare hominin ecospaces on a quantitative scale, we set up a reference sample consisting of mammalian communities of 117 national parks in South Asia and Sub-Saharan Africa. The diversity of such communities is assessed by ecological profiling of specialized herbivore taxa. Moreover, datasets on climate and vegetation correlate with the diversity structure of such specialized herbivore communities. Reconstructing the diversity structure of communities at key sites in Pleistocene Southeast Asia permits to infer features of the climatic and vegetation framework associated with different hominin taxa. Our results show that Homo erectus and Homo sapiens did not occupy similar ecospaces. The ecospace of Homo erectus is characterized by comparatively low diversity among frugivorous and folivorous taxa, while obligate grazers are part of the assemblages. Specialized herbivore communities with such a diversity structure occur at present in East Africa, while they are absent in Southeast Asia. In the reference sample, this type of ecospace corresponds to seasonal wetlands. Although Homo sapiens still inhabits this type of environment in Southeast Asia, his ecospace is wider. Homo sapiens is associated with

  17. An Early Pleistocene Till, Okanagan Valley, British Columbia, Canada

    Barendregt, R. W.; Roed, M.; Smith, S.; Sanborn, P.; Greenough, J.; Layer, P. W.; Huscroft, C.; Mathewes, R.; Benowitz, J.; Tessler, D.

    2011-12-01

    During construction of a road cut related to the Westside Road Interchange Project in West Kelowna, British Columbia, a till was encountered below one of the Lambly Creek valley basalts. The basalts are composed of a number of flows, ranging in age from 0.97 +- 0.05 Ma to 1.62 +-0.25 Ma based on new and available 40Ar/39Ar dating of basalt ground mass. Paleomagnetic data from all major units at the study site fall within one of the normal subchrons of the late Matuyama Reversed Chron and are in general agreement with the radiometric dates. Chemical signatures of the basalt are nearly identical to similar flows belonging to the Chilcotin Group of plateau lavas. This newly identified Chilcotin flow, combined with coeval flows at other locations imply that Chilcotin volcanism was more active during the Quaternary than previously thought. The underlying till is up to four metres thick and is mantled by a minimal Ah horizon in a paleosol. The till overlies laminated and cross bedded fluvial silty sand up to five metres thick that displays injection features and minor faulting. A layer of stratified gravel underlain by gray banded clay of unknown thickness underlies the sand. The till represents the earliest evidence of glaciation in the Okanagan Valley. Till fabric analysis indicates a southeasterly flow of this glacier. The present study site has yielded radiometric ages and polarities similar to those described by Mathews and Rouse for the Dog Creek locality, 320 km to the northwest in south-central British Columbia, where basalts occur below and above glacial deposits. The newly identified glacial till, here referred to as the Westbank First Nations till, is discussed in relation to other Early Pleistocene glaciations in the Cordillera and to the global paleoclimate record. Key Words: Early Pleistocene glaciations, Cordilleran glaciations in western Canada, magnetostratigraphy of glacial sediments, Lambly Creek basalt, Chilcotin Group, Ar/Ar ages of basalts

  18. How Far into Europe Did Pikas (Lagomorpha: Ochotonidae Go during the Pleistocene? New Evidence from Central Iberia.

    César Laplana

    Full Text Available This paper reports the first find of pika remains in the Iberian Peninsula, at a site in central Spain. A fragmented mandible of Ochotona cf. pusilla was unearthed from Layer 3 (deposited some 63.4±5.5 ka ago as determined by thermoluminescence of the Buena Pinta Cave. This record establishes new limits for the genus geographic distribution during the Pleistocene, shifting the previous edge of its known range southwest by some 500 km. It also supports the idea that, even though Europe's alpine mountain ranges represented a barrier that prevented the dispersal into the south to this and other taxa of small mammals from central and eastern Europe, they were crossed or circumvented at the coldest time intervals of the end of the Middle Pleistocene and of the Late Pleistocene. During those periods both the reduction of the forest cover and the emersion of large areas of the continental shelf due to the drop of the sea level probably provided these species a way to surpass this barrier. The pika mandible was found accompanying the remains of other small mammals adapted to cold climates, indicating the presence of steppe environments in central Iberia during the Late Pleistocene.

  19. How Far into Europe Did Pikas (Lagomorpha: Ochotonidae) Go during the Pleistocene? New Evidence from Central Iberia

    Laplana, César; Sevilla, Paloma; Arsuaga, Juan Luis; Arriaza, Mari Carmen; Baquedano, Enrique; Pérez-González, Alfredo

    2015-01-01

    This paper reports the first find of pika remains in the Iberian Peninsula, at a site in central Spain. A fragmented mandible of Ochotona cf. pusilla was unearthed from Layer 3 (deposited some 63.4±5.5 ka ago as determined by thermoluminescence) of the Buena Pinta Cave. This record establishes new limits for the genus geographic distribution during the Pleistocene, shifting the previous edge of its known range southwest by some 500 km. It also supports the idea that, even though Europe’s alpine mountain ranges represented a barrier that prevented the dispersal into the south to this and other taxa of small mammals from central and eastern Europe, they were crossed or circumvented at the coldest time intervals of the end of the Middle Pleistocene and of the Late Pleistocene. During those periods both the reduction of the forest cover and the emersion of large areas of the continental shelf due to the drop of the sea level probably provided these species a way to surpass this barrier. The pika mandible was found accompanying the remains of other small mammals adapted to cold climates, indicating the presence of steppe environments in central Iberia during the Late Pleistocene. PMID:26535576

  20. Pyloniid stratigraphy - A new tool to date tropical radiolarian ooze from the central tropical Indian Ocean

    Gupta, S.M.

    Pyloniid stratigraphy, a faunal abundance-variation stratigraphic tool, similar to Cycladophora davisiana stratigraphy employed at high latitudes, is found to work well for tropical radiolarian ooze. The relationship between the spatial distribution...

  1. The quaternary stratigraphy of a section of the Sibowe River, south-west Swaziland

    G. Van Regenmortel

    1991-01-01

    Full Text Available In south-west Swaziland a river terrace along the Sibowe river is formed by active river incision. A complex profile along this terrace showing alluvial and colluvial deposits reflecting changes in environmental conditions since at least the last 30 000 years is exposed. Examination of soil characteristics, relative position of the composite strata as well as river dynamics leads to a stratigraphie interpretation which has been fitted into a time frame. The basal gravel, alluvial in nature, dates from before the deposition of the Mphunga colluvium which has been deposited between 30 300 and 8490 before present. On the colluvium occurs an alluvium most probably deposited during the Early Holocene. The incision of the terrace to its present level has occurred during the Late Holocene.

  2. A mid to late Holocene history of floodplain and terrace reworking along the middle Delaware River valley, USA

    Stinchcomb, Gary E.; Driese, Steven G.; Nordt, Lee C.; Allen, Peter M.

    2012-10-01

    This study tests and refines the traditional floodplain development model for the partly confined middle Delaware River valley, which has shown that the main channel was relatively stable and flanked by a 6000-8000 year old, vertically accreting alluvial terrace. The Holocene alluvial processes and history presented here in 6 fluvial phases were reconstructed using morphostratigraphy, 36 profile descriptions, 332 grain size analyses, and 82 14C ages from soil trenches, auger borings, and archaeological excavations. Fluvial phases I-III largely validate previous reconstructions showing a late Pleistocene (I: > 10.7 ka) braided stream transition into an early Holocene wandering stream with prolonged floodplain stability (II: 10.7-8 ka), followed by early-middle Holocene erosion and then deposition (III: 8-5 ka). The early and middle Holocene changes in alluvial stratigraphy and sedimentology broadly correlate with climatically derived Holocene subdivisions, suggesting climate change partly controls alluvial response along the middle Delaware River valley. This study documents for the first time a middle Holocene episode of channel incision occurring sometime between 6.0 and 5.0 ka. Although the results reconfirm that the majority of alluvial landforms are composed of vertical accretion deposits, we present here new evidence of oblique, abandoned channel, and lateral accretion deposits inset to similar landforms with different formation histories (i.e., polycyclic terrace development), depicting a river valley that has experienced floodplain and terrace reworking. The majority of floodplain and terrace reworking occurs during the late-middle and late Holocene phases IV-VI (5.5-0 ka), following the middle Holocene incision event. These phases demonstrate floodplain reworking processes in the form of channel abandonment, stripping, flood channeling, and convex bank erosion. The subsequent space filled rapidly with evidence of multistory soil formation, and eventually

  3. Spatial and temporal patterns of Pleistocene biogenic sediment accumulation in the Gulf of Alaska

    Moy, C. M.; Bahlburg, H.; Childress, L. B.; Cowan, E. A.; Forwick, M.; Müller, J.; Ribeiro, F.; Ridgway, K. D.; Mix, A. C.

    2013-12-01

    Reconstructing the timing and nature of past changes in aquatic productivity in the Gulf of Alaska (GoA) can shed light on the primary processes driving biogeochemical cycling over geologic timescales. Today, Fe is an important micronutrient that limits primary productivity in surface waters beyond the continental shelf in much of the GoA. However, we have a relatively poor understanding of how Fe-delivery processes, combined with changing climate, environmental, and oceanographic conditions, interact to influence primary production over glacial-interglacial timescales. An important first step is to identify the spatial and temporal patterns of increased productivity in the sediment record. Here, we present sedimentologic and physical property data from IODP Expedition 341 and identify intervals where diatom ooze and diatom-rich mud lithofacies are prevalent during the Pleistocene. Among the Expedition 341 recovered cores, were high-recovery intervals in the outer (Site U1417) and inner (U1418) Surveyor Fan, and from a small slope basin at the edge of the continental shelf (Site U1419). In general, greenish gray diatomaceous ooze (containing >50 % diatoms in smear slides) and diatom-rich mud (>25% diatoms) is found in beds ranging in thickness from 20 to 150 cm, interbedded with gray mud that commonly contains lonestones. Ooze is occasionally found immediately overlying volcanic ash. Compared to non-biogenic mud, diatomaceous sediments are generally characterized by lower magnetic susceptibility, natural gamma ray, bulk density, and higher b* color reflectance. At Site U1417, we observe a frequent occurrence of diatomaceous ooze during the middle Pleistocene relative to the early and late Pleistocene. At Site U1418, intervals containing diatom ooze are less common than at U1417 and biogenic sediments are mainly observed within the late Pleistocene portion of the record. However, higher sedimentation rates at U1418 relative to U1417, and the co-occurrence of sand

  4. A Parable of Small Animals and Megafauna Extinction: A Paleo-Economic Theory of Climate Change versus Human Overkill in the Pleistocene

    Bulte, E.H.; Horan, R.D.; Shogren, J.F.

    2006-01-01

    After centuries of debate, paleontologists are converging towards the conclusion that human overkill caused the massive extinction of large mammals in the late Pleistocene. This paper revisits the question of megafauna extinction by incorporating economic behavior into the debate. We allow for endog

  5. Revision of the early Middle Pleistocene bears (Ursidae, Mammalia) of Central Europe, with special respect to possible co-occurrence of spelaeoid and arctoid lineages

    Wagner, J.; Čermák, Stanislav

    2012-01-01

    Roč. 87, č. 3 (2012), s. 461-496. ISSN 1214-1119 Institutional research plan: CEZ:AV0Z30130516 Keywords : Ursus deningeri * U. arctos, * Late Biharian * Early Toringian * Middle Pleistocene Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.141, year: 2012 http://www.geology.cz/bulletin/fulltext/1354_Wagner.pdf

  6. Estratigrafía y sedimentología de las unidades del Cretácico superior-Paleógeno aflorantes en la margen sureste del lago Viedma, provincia de Santa Cruz, Argentina Stratigraphy and sedimentology of the Late Cretaceous-Paleogene units cropping out at the south-eastern margin of Lake Viedma, Santa Cruz Province, Argentina

    SA Marenssi

    2003-09-01

    Full Text Available En el sureste del lago Viedma afloran sedimentitas del Cretácico superior y Paleógeno de la cuenca Austral. En el perfil de Barrancas Blancas se describen 28 m de areniscas y fangolitas amarillentas correspondientes al Miembro La Asunción de la Formación Anita que son cubiertas en forma concordante y transicional por 390 m de areniscas y pelitas grisáceas de la Formación Cerro Fortaleza. Las primeras representan la progradación de ambientes de plataforma marina dominada por el oleaje mientras que las segundas atestiguan la sedimentación en ambientes transicionales, fluviales y fluviales con acción mareal. La evolución general de los paleoambientes sedimentarios y secuencias depositacionales, la procedencia de las areniscas y direcciones de paleocorrientes indican que estas rocas fueron depositadas durante la etapa de cuenca de retroarco (sag. En el cerro Pirámides se hallan presentes sedimentitas terciarias que se disponen en contacto tectónico sobre las rocas de la Formación Cerro Fortaleza. El escaso espesor preservado de las areniscas verdes de la Formación Man Aike (Late Cretaceous and Paleogene sedimentary rocks of the Austral Basin crop out on the south-eastern margin of Lake Viedma. In the Barrancas Blancas section, 28 m of yellowish sandstone and mudstone of the La Asunción Member of the Anita Formation are transitionally covered by 390 m of greyish sandstone and mudstone of the Cerro Fortaleza Formation. The former represent a prograding barred nearshore system, whereas the latter correspond to paralic, fluvial and fluvial-tidal sedimentation. The evolution of the depositional sequences, sedimentary palaeoenvironments, sandstone provenance and palaeocurrents indicate that the sediments were deposited during the back-arc (sag stage of the basin. At Cerro Piramides, Tertiary sedimentary rocks rest with fault contact on top of the Cerro Fortaleza Formation. The limited thickness (<1m preserved of greenish sandstone of the

  7. A description of the geological context, discrete traits, and linear morphometrics of the Middle Pleistocene hominin from Dali, Shaanxi Province, China.

    Wu, Xinzhi; Athreya, Sheela

    2013-01-01

    In 1978, a nearly complete hominin fossil cranium was recovered from loess deposits at the site of Dali in Shaanxi Province, northwestern China. It was subsequently briefly described in both English and Chinese publications. Here we present a comprehensive univariate and nonmetric description of the specimen and provide comparisons with key Middle Pleistocene Homo erectus and non-erectus hominins from Eurasia and Africa. In both respects we find affinities with Chinese H. erectus as well as African and European Middle Pleistocene hominins typically referred to as Homo heidelbergensis. Specifically, the Dali specimen possesses a low cranial height, relatively short and arched parietal bones, an angled occipital bone, and a nonprominent articular tubercle relative to the preglenoid surface all of which distinguish it from Afro/European Middle Pleistocene Homo and align it with Asian H. erectus. At the same time, it displays a more derived morphology of the supraorbital torus and supratoral sulcus and a thinner tympanic plate than H. erectus, a relatively long upper (lambda-inion) occipital plane with a clear separation of inion and opisthocranion, and an absolute and relative increase in brain size, all of which align it with African and European Middle Pleistocene Homo. Finally, traits such as the form of the frontal keel and the relatively short, broad midface align Dali specifically with other Chinese specimens from the Middle Pleistocene and Late Pleistocene, including H. erectus, and differentiate these from the Afro/European specimens of this time period. PMID:23283667

  8. Pátek, Levousy a Chlumčany – významné fosiliferní středopleistocénní lokality na pravém břehu Ohře mezi Louny a Libochovicemi Pátek, Levousy and Chlumčany – important mid-pleistocene localities on the right bank of the Ohře River between Louny and Libochovice

    Ivan Horáček

    2005-05-01

    Full Text Available Due to a complete predominance of non-calcareous fluvial sediments in the Czech Republic, any find of fossil malacofauna is always considered as rare. The present work describes three localities in the Ohře river area, which contain, especially in the case of the Pátek locality, very abundant mid-Pleistocene malacofaunas. They were mainly collected in the floodplain fine-grained loam and back swamp deposits but also in sandy gravels. The molluscan thanatocenoses from localities near the Pátek village indicate the interglacial maximum (with up to 25 forest species s.l., which developed directly on a 30 m thick river terrace dating back to the period, during which the Ohře river established its present-day easterly course. The fossil molluscs from the Levousy locality come from floodplain loam deposits as well as from the underlying sandy terrace gravels. The species distribution, nevertheless, indicates only a transitional glacial-interglacial period. The somewhat higher morphologic position of the locality, as well as that of another section at Chlumčany, and complete predominance of local late Cretaceous material indicates that the Ohře river did not flow to the east yet during the accumulation of the floodplain deposits with molluscs, but still to the north, towards Bílina. The terrestrial malacofauna from the Chlumčany section came from floodplain marls, particularly from sandy tufa deposits in the alluvium, which contains no forest-biotope elements, but the presence of the species Columella columella – distinct representative of our „coldest“ loess deposits – is an absolute surprise, since the peak of production of the sandy tufa deposits has always been associated with climate optima of the interglacials and of the Holocene. Therefore, the described malacofaunas come from a boundary period, during which the Ohře river did not use its present-day valley (Levousy and Clumčany yet. Then, from the oldest time span, it took up

  9. Pleistocene glacial terminations triggered by synchronous changes in Southern and Northern Hemisphere insolation: The insolation canon hypothesis

    Schulz, Kai; Zeebe, Richard E.

    2007-01-01

    Throughout the last similar to 900 kyr, the Late Pleistocene, Earth has experienced periods of cold glacial climate, punctuated by seven abrupt transitions to warm interglacials, the so-called terminations. Although most of glacial ice is located in the Northern Hemisphere (NH), the Southern Hemisphere (SH) seems to play a crucial role in deglaciation. Variation in the seasonal distribution of solar insolation is one candidate for the cause of these climatic shifts. But so far, no simple mech...

  10. Origin and hydrogeochemistry of a shallow flow-through lake on a Pleistocene piedmont, northern Spanish Meseta

    Margarita Jambrina; Ildefonso Armenteros; Ángel Corrochano; Clemente Recio

    2013-01-01

    The Cristo lagoon, situated on Neogene deposits in the northern Spanish Meseta, occupies a shallow depression on a Pleistocene piedmont. The development of the lacustrine depression on the piedmont was favoured by the fault network, reinforced by substrateloss by weathering, probably during the late Quaternary. Even during the hot summer season, salinity is low, with concentrations of total dissolved solids (TDS) being around 150 mg L–1. Only when the lagoon is almost dry do TDS concentration...

  11. Magnetic iron-nickel sulphides in the Pliocene and Pleistocene marine marls from the Vrica section (Calabria, Italy)

    A.J. Van Velzen; Dekkers, M.J.; Zijderveld, J.D.A.

    1993-01-01

    The rock magnetic properties of the late Pliocene and early Pleistocene open-marine marls from the Vrica section in Calabria (Italy) point to magnetic sulphide as the main magnetic mineral and remanence carrier. The maximum blocking temperatures, however, are between 340 and 360°C, which is too high for stoichiometric monoclinic pyrrhotite. Magnetic concentrates of the sediment are rich in iron sulphide grains and iron-nickel sulphide grains. Microprobe observations show that most of the grai...

  12. Late Budgets

    Andersen, Asger Lau; Lassen, David Dreyer; Nielsen, Lasse Holbøll Westh

    The budget forms the legal basis of government spending. If a budget is not in place at the beginning of the fiscal year, planning as well as current spending are jeopardized and government shutdown may result. This paper develops a continuous-time war-of-attrition model of budgeting in a...... presidential style-democracy to explain the duration of budget negotiations. We build our model around budget baselines as reference points for loss averse negotiators. We derive three testable hypotheses: there are more late budgets, and they are more late, when fiscal circumstances change; when such changes...... are negative rather than positive; and when there is divided government. We test the hypotheses of the model using a unique data set of late budgets for US state governments, based on dates of budget approval collected from news reports and a survey of state budget o¢ cers for the period 1988...

  13. Latest Proterozoic stratigraphy and earth history

    Knoll, Andrew H.; Walter, Malcolm R.

    1992-01-01

    Novel biostratigraphic and chemostratigraphic data furnish an improved framework for stratigraphic correlation of the Proterozoic Eon as well as tools for a chronostratigraphic division of the late Proterozoic. It is argued that, in conjunction with geochronometric data, protistan microfossils and isotope geochemistry can furnish a means for an eventual integration of the latest Proterozoic Eon. Attention is given to the emerging methodologies of fossil protists and prokaryotes and of isotopic chemostratigraphy.

  14. Orbital obliquity cycles recorded in Kuroshio Current region, eastern Asia, around Plio-Pleistocene boundary

    Iwatani, Hokuto; Kondo, Yasuo; Irizuki, Toshiaki; Iwai, Masao; Ikehara, Minoru

    2016-05-01

    Global climate underwent a period of significant cooling at the Plio-Pleistocene Transition (∼2.6 Ma). The influence of this change on the Kuroshio Current region in the Pacific Ocean, off eastern Asia, is not well known. In this study, we clarify temporal changes in the paleoenvironment under the influence of the Kuroshio Current during the late Pliocene and early Pleistocene using high-resolution faunal proxy records of fossil Ostracoda (Crustacea). The study unit is the Ananai Formation in the southeastern region of Shikoku, southwest Japan. The modern analog technique (MAT) is employed for the quantitative estimation of paleo-bottom water temperatures (PBWTs) and paleo-water depth (PWD) during the deposition of the formation. Ostracode MAT results show PBWT fluctuations during warmest and coldest months, with values of 16°C-20 °C and 12°C-16 °C, respectively, and a PWD of 70-140 m, reflecting sea-level oscillations. Moreover, the PBWT in the coldest month is 3 °C-4 °C lower than present-day water temperatures at the same shallow water depths. Temporal changes in these paleoenvironmental variables based on MAT are in good agreement with global oxygen isotope records. Orbital obliquity cycles with 41-kyr periodicity are recorded for the first time in an onshore section in the Kuroshio Current region at the Plio-Pleistocene boundary interval.

  15. Similar millennial climate variability on the Iberian margin during two early Pleistocene glacials and MIS 3

    Birner, B.; Hodell, D. A.; Tzedakis, P. C.; Skinner, L. C.

    2016-01-01

    Although millennial-scale climate variability (MIS) 37-41 from approximately 1235 to 1320 ka) during the "41 ka world" at Integrated Ocean Drilling Program Site U1385 (the "Shackleton Site") on the southwest Iberian margin. Millennial-scale climate variability was suppressed during interglacial periods (MIS 37, MIS 39, and MIS 41) and activated during glacial inceptions when benthic δ18O exceeded 3.2‰. Millennial variability during glacials MIS 38 and MIS 40 closely resembled Dansgaard-Oeschger events from the last glacial (MIS 3) in amplitude, shape, and pacing. The phasing of oxygen and carbon isotope variability is consistent with an active oceanic thermal bipolar see-saw between the Northern and Southern Hemispheres during most of the prominent stadials. Surface cooling was associated with systematic decreases in benthic carbon isotopes, indicating concomitant changes in the meridional overturning circulation. A comparison to other North Atlantic records of ice rafting during the early Pleistocene suggests that freshwater forcing, as proposed for the late Pleistocene, was involved in triggering or amplifying perturbations of the North Atlantic circulation that elicited a bipolar see-saw response. Our findings support similarities in the operation of the climate system occurring on millennial time scales before and after the Middle Pleistocene Transition despite the increases in global ice volume and duration of the glacial cycles.

  16. Reading and Abstracting Journal Articles in Sedimentology and Stratigraphy.

    Conrad, Susan Howes

    1991-01-01

    An assignment centered on reading journal articles and writing abstracts is an effective way to improve student reading and writing skills in sedimentology and stratigraphy laboratories. Each student reads two articles and writes informative abstracts from the author's point of view. (PR)

  17. Direct U-series analysis of the Lezetxiki humerus reveals a Middle Pleistocene age for human remains in the Basque Country (northern Iberia).

    de-la-Rúa, Concepción; Altuna, Jesús; Hervella, Monserrat; Kinsley, Leslie; Grün, Rainer

    2016-04-01

    In 1964, a human humerus was found in a sedimentary deposit in Lezetxiki Cave (Basque Country, northern Iberia). The first studies on the stratigraphy, associated mammal faunal remains and lithic implements placed the deposits containing the humerus into the Riss glacial stage. Direct chronometric evidence has so far been missing, and the previous chronostratigraphic framework and faunal dating gave inconsistent results. Here we report laser ablation U-series analyses on the humerus yielding a minimum age of 164 ± 9 ka, corresponding to MIS 6. This is the only direct dating analysis of the Lezetxiki humerus and confirms a Middle Pleistocene age for this hominin fossil. Morphometric analyses suggest that the Lezetxiki humerus has close affinities to other Middle Pleistocene archaic hominins, such as those from La Sima de los Huesos at Atapuerca. This emphasizes the significance of the Lezetxiki fossil within the populations that predate the Neanderthals in south-western Europe. It is thus an important key fossil for the understanding of human evolution in Europe during the Middle Pleistocene, a time period when a great morphological diversity is observed but whose phylogenetic meaning is not yet fully understood. PMID:27086059

  18. Dark humic alluvial paleosols in Central and Southern Mexico: Micromorphological indicators of Late Pleistocene megafauna habitats Paleosuelos aluviales con humus oscuro en el Centro y Sur de México: indicadores micromorfológicos de los hábitats de la megafauna del Pleistoceno tardío Paleosolos aluviais com húmus escuro no Centro e Sul do México: indicadores micromorfológicos dos habitats da megafauna do Pleistocénico tardio

    Rosa E. Tovar

    2013-11-01

    Full Text Available During the Late Pleistocene, Mexico had a richer fauna than today with many different forms of megafauna that are now extinct. However, the ecosystems they inhabited and the particular ecological niches that they occupied are still poorly understood. Most of the findings of Pleistocene megafauna have been in alluvial deposits that present rich opportunities for paleoecological studies using paleopedological records. Floodplain paleosols commonly are poorly developed. However, micromorphological analysis provides information about the grade of development of the soil at a microscale, discriminating between genetic and sedimentary processes; thus helping in the identification of the environmental setting in which they formed. We analyzed the micromorphology of six pedogenetic units in the sequences of Santa Cruz Nuevo and Axamilpa, in the south of Puebla, and Huexoyucan, in the state of Tlaxcala. These pedosequences correspond to the second half of marine isotopic stage 3 (MIS3, MIS2 and the early Holocene. All studied units are characterized by strong pigmentation with dark humus. The micromorphological analysis of MIS3 paleosols reveals aquatic conditions with evidence of freshwater biota and microlamination as well as pedogenetic features of hydrogenic carbonate precipitation and redoximorphic processes. The dark paleosols of MIS2 and the early Holocene demonstrate signs of stronger coprogenic aggregation, weathering and fewer gleyic features. Comparison with modern soils shows that the latter were formed under better-drained, aerated conditions that exclude redoximorphic processes. We conclude that the dark colored Pleistocene paleosol units are indicative of different paleo-landscapes: wetlands in the MIS3 and moist meadows in MIS2 – early Holocene. The swampy ecosystems could play an important role as a megafauna habitat.En el Pleistoceno Tardío, México tenía una diversidad faunística más rica que en la actualidad, con diferentes

  19. A new early Pleistocene hominin mandible from Atapuerca-TD6, Spain.

    Bermúdez de Castro, José María; Pérez-González, Alfredo; Martinón-Torres, María; Gómez-Robles, Aida; Rosell, Jordi; Prado, Leyre; Sarmiento, Susana; Carbonell, Eudald

    2008-10-01

    We present the description of a new mandibular specimen, ATD6-113, recovered in 2006 from the TD6 level of the Gran Dolina cave site in Sierra de Atapuerca, northern Spain. A detailed study of the lithostratigraphy of the top sequence of this level, the section from where all human remains have been recovered so far, is also presented. We have observed that the hominin stratum, previously defined as Aurora Stratum, represents a condensed deposit of at least six layers, which could not be distinguished in the test pit made in 1994-95. Therefore, the human fossil remains were probably deposited during a discrete and undetermined time period. The new mandibular fragment exhibits a very similar morphology to that of the most complete specimen, ATD6-96, which was recovered in 2003 from a different layer. This suggests that both specimens represent the same biological population. The two mandibles, as well as the small mandibular fragment ATD6-5 (which constitutes part of the holotype of Homo antecessor), present a morphological pattern clearly derived with regard to that of the African early Homo specimens usually included in H. habilis and H. rudolfensis, the mandibles D211 and D2735 from Dmanisi, and most of the early Pleistocene mandibles from Sangiran. The TD6 mandibles also exhibit some derived features with regard to the African early Pleistocene specimens included in H. ergaster (or African H. erectus). Thus, the TD6 hominins seem to represent a lineage different from other African and Asian lineages, although some (metric in particular) similarities with Chinese middle Pleistocene mandibles are noted. Interestingly, none of the apomorphic mandibular features of the European middle and early late Pleistocene hominins are present in the TD6 mandibles. PMID:18657300

  20. Cenozoic stratigraphy of the Sahara, Northern Africa

    Swezey, Christopher S.

    2009-01-01

    This paper presents an overview of the Cenozoic stratigraphic record in the Sahara, and shows that the strata display some remarkably similar characteristics across much of the region. In fact, some lithologies of certain ages are exceptionally widespread and persistent, and many of the changes from one lithology to another appear to have been relatively synchronous across the Sahara. The general stratigraphic succession is that of a transition from early Cenozoic carbonate strata to late Cenozoic siliciclastic strata. This transition in lithology coincides with a long-term eustatic fall in sea level since the middle Cretaceous and with a global climate transition from a Late Cretaceous–Early Eocene “warm mode” to a Late Eocene–Quaternary “cool mode”. Much of the shorter-term stratigraphic variability in the Sahara (and even the regional unconformities) also can be correlated with specific changes in sea level, climate, and tectonic activity during the Cenozoic. Specifically, Paleocene and Eocene carbonate strata and phosphate are suggestive of a warm and humid climate, whereas latest Eocene evaporitic strata (and an end-Eocene regional unconformity) are correlated with a eustatic fall in sea level, the build-up of ice in Antarctica, and the appearance of relatively arid climates in the Sahara. The absence of Oligocene strata throughout much of the Sahara is attributed to the effects of generally low eustatic sea level during the Oligocene and tectonic uplift in certain areas during the Late Eocene and Oligocene. Miocene sandstone and conglomerate are attributed to the effects of continued tectonic uplift around the Sahara, generally low eustatic sea level, and enough rainfall to support the development of extensive fluvial systems. Middle–Upper Miocene carbonate strata accumulated in northern Libya in response to a eustatic rise in sea level, whereas Upper Miocene mudstone accumulated along the south side of the Atlas Mountains because uplift of the

  1. Holocene alluvial stratigraphy and response to climate change in the Roaring River valley, Front Range, Colorado, USA

    Madole, Richard F.

    2012-01-01

    Stratigraphic analyses and radiocarbon geochronology of alluvial deposits exposed along the Roaring River, Colorado, lead to three principal conclusions: (1) the opinion that stream channels in the higher parts of the Front Range are relics of the Pleistocene and nonalluvial under the present climate, as argued in a water-rights trial USA v. Colorado, is untenable, (2) beds of clast-supported gravel alternate in vertical succession with beds of fine-grained sediment (sand, mud, and peat) in response to centennial-scale changes in snowmelt-driven peak discharges, and (3) alluvial strata provide information about Holocene climate history that complements the history provided by cirque moraines, periglacial deposits, and paleontological data. Most alluvial strata are of late Holocene age and record, among other things, that: (1) the largest peak flows since the end of the Pleistocene occurred during the late Holocene; (2) the occurrence of a mid- to late Holocene interval (~2450–1630(?) cal yr BP) of warmer climate, which is not clearly identified in palynological records; and (3) the Little Ice Age climate seems to have had little impact on stream channels, except perhaps for minor (~1 m) incision. Published

  2. East Greenland Caledonides: stratigraphy, structure and geochronology: Lower Palaeozoic stratigraphy of the East Greenland Caledonides

    Smith, M. Paul

    2004-12-01

    Full Text Available The Lower Palaeozoic stratigraphy of the East Greenland Caledonides, from the fjord region of North-East Greenland northwards to Kronprins Christian Land, is reviewed and a number of new lithostratigraphical units are proposed. The Slottet Formation (new is a Lower Cambrian quartzite unit, containing Skolithos burrows, that is present in the Målebjerg and Eleonore Sø tectonic windows, in the nunatak region of North-East Greenland. The unit is the source of common and often-reported glacial erratic boulders containing Skolithos that are distributed throughout the fjord region. The Målebjerg Formation (new overlies the Slottet Formation in the tectonic windows, and comprises limestones and dolostones of assumed Cambrian–Ordovician age. The Lower Palaeozoic succession of the fjord region of East Greenland (dominantly limestones and dolostones is formally placed in the Kong Oscar Fjord Group (new. Amendments are proposed for several existing units in the Kronprins Christian Land and Lambert Land areas, where they occur in autochthonous, parautochthonous and allochthonous settings.

  3. Stratigraphy of Atlantic coastal margin of United States north of Cape Hatteras; brief survey

    Perry, W.J.; Minard, J.P.; Weed, E.G.A.; Robbins, E.I.; Rhodehamel, E.C.

    1975-01-01

    A synthesis of studies of sea-floor outcrops of the sedimentary wedge beneath the northeastern United States continental shelf and slope and a reassessment of coastal plain Mesozoic stratigraphy, particularly of the coastal margin, provide insight for estimating the oil and gas potential and provide geologic control for marine seismic investigations of the Atlantic continental margin. The oldest strata known to crop out on the continental slope are late Campanian in age. The Cretaceous-Tertiary contact along the slope ranges from a water depth of 0.6 to 1.5 km south of Georges Bank to 1.8 km in Hudson Canyon. Few samples are available from Tertiary and Late Cretaceous outcrops along the slope. Sediments of the Potomac Group, chiefly of Early Cretaceous age, constitute a major deltaic sequence in the emerged coastal plain. This thick sequence lies under coastal Virginia, Maryland, Delaware, southeastern New Jersey, and the adjacent continental shelf. Marine sands associated with this deltaic sequence may be present seaward under the outer continental shelf. South of the Norfolk arch, under coastal North Carolina, carbonate rocks interfinger with Lower Cretaceous clastic strata. From all available data, Mesozoic correlations in coastal wells between coastal Virginia and Long Island have been revised. The Upper-Lower Cretaceous boundary is placed at the transition between Albian and Cenomanian floras. Potential hydrocarbon source beds are present along the coast in the subsurface sediments of Cretaceous age. Potential reservoir sandstones are abundant in this sequence.

  4. Holocene tephra stratigraphy in four lakes in southeastern Oregon and northwestern Nevada, USA

    Foit, Franklin F.; Mehringer, Peter J.

    2016-03-01

    To better understand the regional tephra stratigraphy and chronology of northern Nevada and southern Oregon, tephras in archived cores, taken as part of the Steens Mountain Prehistory Project from four lakes, Diamond Pond, Fish and Wildhorse lakes in southeastern Oregon and Blue Lake in northwestern Nevada, were reexamined using more advanced electron microprobe analytical technology. The best preserved and most complete core from Fish Lake along with Wildhorse Lake hosted two tephras from Mt. Mazama (Llao Rock and the Climactic Mazama), a mid-Holocene basaltic tephra from Diamond Craters, Oregon, two Medicine Lake tephras and an unexpected late Holocene Chaos Crags (Mt. Lassen volcanic center) tephra which was also found in the other lakes. Blue Lake was the only lake that hosted a Devils Hill tephra from the Three Sisters volcano in west central Oregon. Another tephra from the Three Sisters Volcano previously reported in sediments of Twin Lakes in NE Oregon, has now been confirmed as Rock Mesa tephra. The Chaos Crags, Devils Hill and Rock Mesa tephras are important late Holocene stratigraphic markers for central and eastern Oregon and northwestern Nevada.

  5. Siphateles (Gila) sp. and Catostomus sp. from the Pleistocene OIS-6 Lake Gale, Panamint Valley, Owens River system, California

    Jayko, A. S.; Forester, R. M.; Smith, G. R.

    2014-12-01

    Panamint Valley lies within the Owens River system which linked southeastern Sierra Nevada basins between Mono Lake and Death Valley during glacial-pluvial times. Previous work indicates that late Pleistocene glacial-pluvial Lake Gale, Panamint Valley was an open system during OIS-6, a closed ground water supported shallow lake during OIS-4, and the terminal lake basin for the Owens River system during OIS-2. We here report the first occurrence of fossil fish from the Plio-Pleistocene Panamint basin. Fish remains are present in late Pleistocene OIS-6 nearshore deposits associated with a highstand that was spillway limited at Wingate Wash. The deposits contain small minnow-sized remains from both Siphateles or Gila sp. (chubs) and Catostomus sp. (suckers) from at least four locations widely dispersed in the basin. Siphateles or Gila sp. and Catostomus are indigenous to the Pleistocene and modern Owens River system, in particular to the historic Owens Lake area. Cyprinodon (pupfish) and Rhinichthys (dace) are known from the modern Amargosa River and from Plio-Pleistocene deposits in Death Valley to the east. The late Pleistocene OIS-6 to OIS-2 lacustrine and paleohydrologic record in Panamint basin is interpreted from ostracod assemblages, relative abundance of Artemia sp. pellets, shallow water indicators including tufa fragments, ruppia sp. fragments and the relative abundance of charophyte gyrogonites obtained from archived core, as well as faunal assemblages from paleoshoreline and nearshore deposits. The OIS-4 groundwater supported shallow saline lake had sufficiently low ratios of alkalinity to calcium (alk/Ca) to support the occurrence of exotic Elphidium sp. (?) foraminfera which are not observed in either OIS-2 or OIS-6 lacustrine deposits. The arrival of Owens River surface water into Panamint Basin during OIS-2 is recorded by the first appearance of the ostracod Limnocythere sappaensis at ~27 m depth in an ~100 m archived core (Smith and Pratt, 1957) which

  6. Global sensitivity analysis of the Indian monsoon during the Pleistocene

    Araya-Melo, P. A.; Crucifix, M.; Bounceur, N.

    2015-01-01

    The sensitivity of the Indian monsoon to the full spectrum of climatic conditions experienced during the Pleistocene is estimated using the climate model HadCM3. The methodology follows a global sensitivity analysis based on the emulator approach of Oakley and O'Hagan (2004) implemented following a three-step strategy: (1) development of an experiment plan, designed to efficiently sample a five-dimensional input space spanning Pleistocene astronomical configurations (three parameters), CO2 concentration and a Northern Hemisphere glaciation index; (2) development, calibration and validation of an emulator of HadCM3 in order to estimate the response of the Indian monsoon over the full input space spanned by the experiment design; and (3) estimation and interpreting of sensitivity diagnostics, including sensitivity measures, in order to synthesise the relative importance of input factors on monsoon dynamics, estimate the phase of the monsoon intensity response with respect to that of insolation, and detect potential non-linear phenomena. By focusing on surface temperature, precipitation, mixed-layer depth and sea-surface temperature over the monsoon region during the summer season (June-July-August-September), we show that precession controls the response of four variables: continental temperature in phase with June to July insolation, high glaciation favouring a late-phase response, sea-surface temperature in phase with May insolation, continental precipitation in phase with July insolation, and mixed-layer depth in antiphase with the latter. CO2 variations control temperature variance with an amplitude similar to that of precession. The effect of glaciation is dominated by the albedo forcing, and its effect on precipitation competes with that of precession. Obliquity is a secondary effect, negligible on most variables except sea-surface temperature. It is also shown that orography forcing reduces the glacial cooling, and even has a positive effect on precipitation

  7. An overview of the Cretaceous stratigraphy and facies development of the Yazd Block, western Central Iran

    Wilmsen, Markus; Fürsich, Franz Theodor; Majidifard, Mahmoud Reza

    2015-04-01

    The Cretaceous successions of the Yazd Block, the western of three structural blocks of the Central-East Iranian Microcontinent (CEIM), have been studied using an integrated approach of litho-, bio- and sequence stratigraphy associated with litho-, bio- and microfacies analyses. The Cretaceous System of that area is in excess of 5 km thick and a generalized relative sea-level curve can be inferred from the facies and thickness development. This curve can be subdivided into two transgressive-regressive megacycles (TRMs), separated by a major tectonic unconformity in the Upper Turonian. TRM 1 comprises the Early Cretaceous to Middle Turonian, TRM 2 the Coniacian to Maastrichtian. TRM 1 starts with up to 1500-m-thick conglomerates and sandstones covering Palaeozoic-Triassic basement rocks, metasediments, or Upper Jurassic-lowermost Cretaceous granites. The basal tectonic unconformity, related to the Late Cimmerian event (Jurassic-Cretaceous boundary interval), shows a pronounced palaeo-relief that is levelled by the basal siliciclastic formations. Sparse biostratigraphic data from calcareous intercalations in the upper part of these strata indicate a Hauterivian to Barremian age. The Aptian facies development is marked by the onlap of thick-bedded, micritic carbonates with abundant orbitolinid foraminifera and rudists representing a large-scale shallow-marine carbonate platform system that fringed the Yazd Block in the north and west. These platforms are up to 1000 m thick and drowned during the middle to Late Aptian, followed by up to 1500-m-thick basinal marly sediments of Late Aptian to mid-Late Albian ages, representing the maximum relative sea-level during TRM 1. During the latest Albian-Middle Turonian, a gradual shallowing is indicated by progradation of shallow-water skeletal limestones separated by marl tongues, representing a carbonate ramp system. Strata of TRM 2 overlie older units along a regional angular unconformity and indicate tectonic stability and

  8. Sedimentology and Ground-Penetrating Radar Characteristics of a Pleistocene Sandur Deposit

    Olsen, Henrik; Andreasen, Frank Erik

    1995-01-01

    The Kronhede sandur forms part of a ca. 1500 km2 Late Pleistocene outwash system located in western Jylland, Denmark. A sedimentological study was carried out in the proximal part of the sandur. The sediments were deposited during progradation of the glacier as shown by a general coarsening-upwar......-dimensional geometry of the jökulhlaup deposit, forming the top part of the succession. The paper describes the sedimentology of the sandur deposits and the application of the ground-penetrating radar technique to sedimentary architecture studies.......The Kronhede sandur forms part of a ca. 1500 km2 Late Pleistocene outwash system located in western Jylland, Denmark. A sedimentological study was carried out in the proximal part of the sandur. The sediments were deposited during progradation of the glacier as shown by a general coarsening......-upward lithology, terminating with a jökulhlaup episode characterized by large compound dune migration and slack-water draping. Mapping of a more than 200 m long well exposed pitwall and ground-penetrating radar measurements in a 50 × 200 m grid along the pitwall made it possible to outline the three...

  9. The Watinglo mandible: a second terminal Pleistocene Homo sapiens fossil from tropical Sahul with a test on existing models for the human settlement of the region.

    Bulbeck, D; O'Connor, S

    2011-02-01

    This paper analyses a fossil human mandible, dated to circa 10ka, from Watinglo rockshelter on the north coast of Papua New Guinea. The fossil is metrically and morphologically similar to male mandibles of recent Melanesians and Australian Aborigines. It is distinguished from Kow Swamp and Coobool Creek male mandibles (Murray Valley, terminal Pleistocene) by being smaller and having different shape characteristics, as well as smaller teeth and a slower rate of tooth wear. It pairs with the Liang Lemdubu female (Late Glacial Maximum, Aru Islands) in suggesting that the morphology of the terminal Pleistocene inhabitants of tropical Sahul was gracile compared to their contemporaries within the southern Murray drainage. An explanatory scenario for this morphological contrast is developed in the context of the Homo sapiens early fossil record, Australasian mtDNA evidence, terminal Pleistocene climatic variation, and the possibility of multiple entry points into Sahul. PMID:21216399

  10. The pollen stratigraphy of late Quaternary lake sediments of South-West Greenland

    Kelly, Michael; Funder, Svend Visby

    1974-01-01

    by a mid postglacial phase in which there is the successive appearance of woody scrub species. A final phase shows the decline of some of these. This is interpreted as a general response to a broad amplitude fluctuation in climate, with its optimal period lying between c. 7600 and 3200 B.P. The...... detailed composition of the vegetation however is influenced by immigration phenomena, with the appearance of many species lagging behind the attainment of their climatic thresholds. Detailed consideration is given to the possibility of Alnus crispa being present as a scrub component during the climatic...

  11. Late Quaternary seismic sequence stratigraphy of the Gulf of Kachchh, northwest of India

    Michael, L.; Rao, D.G.; Krishna, K.S.; Vora, K.H.

    unit `A` up to 12 m thick, (2) thick 8 to 10 m diffuse seismic reflection free unit `D,` and (3) 4 to 5 m thick hummocky reflections unit `K`. The geomorphic/subsurface features are pinnacles (1 to 2 m high) and mounds (4 to 5 m high) on the seafloor...

  12. Human influence on late Holocene fluvial landscape and stratigraphy in the Mixteca Alta of Oaxaca, Mexico

    Leigh, D. S.; Holdridge, G. H.; Kowalewski, S. A.

    2011-12-01

    The Mixteca Alta of south-central Mexico (state of Oaxaca) is a high-elevation plateau where population and agricultural steadily grew over the past 3000 years, but with a few significant episodes of population decline. Currently, the landscape is highly eroded and gullied in response to widespread land abandonment and diminished population attributed to the Spanish conquest during the 1500s and 1600s. Abandonment apparently resulted in neglect of prehistoric cross-drainage retaining walls, known as lama-bordos, which had been constructed throughout agricultural watersheds for millennia to retain runoff and sediment. Our research seeks to establish the earliest ages for construction of lama-bordos, which are buried by more than 10 m of alluvium in some localities; and we hope to determine if the chronology of alluvial sedimentation is related to fluctuations in population density versus climate changes or other drivers. Sampling is focused on relatively small tributary watersheds (4000 cal yr BP cut-and-fill stratigraphic units commonly contain detritus from upland subsoil and underlying bedrock. We provide numerous radiocarbon dates for the oldest lama-bordos, and they suggest that initial construction predates 2500 cal yr BP, which is older than prevailing archaeological evidence has indicated. It appears the lama-bordos were constructed to trap gully-derived upland sediment to facilitate agriculture (largely maize cultivation). Geochemistry and lithology indicate excellent discrimination of upland soil-surface versus upland gully-derived subsoil detritus, so we are optimistic about correlating periods of exacerbated upland erosion with cultural periods of abandonment. This correlation of upland gully erosion and rapid bottomland sedimentation appears clear for the post-conquest abandonment period (1520s-1600s) until bottomlands also became gullied during the middle 1600s, but we await more radiocarbon dates to extend such correlations back in time to fully test our hypothesis. Our research is shedding new light on the extent to which people have manipulated and managed upland erosion and bottomland sedimentation for thousands of years in Mesoamerica.

  13. The challenge of dating Early Pleistocene fossil teeth by the combined uranium series-electron spin resonance method: the Venta Micena palaeontological site (Orce, Spain)

    The palaeontological site of Venta Micena (Orce, Andalusia, Spain) lies in the eastern sector of the Guadix-Baza basin, one of the best documented areas in Europe for Plio-Pleistocene bio-stratigraphy. The combination of bio-chronological and palaeo-magnetic results, combined with the radiometric data obtained for Atapuerca Sima del Elefante, indicated that the Venta Micena stratum was formed between the Jaramillo and Olduvai palaeo-magnetic events, most likely between 1.22 and 1.77 Ma. Five fossil teeth from two outcrops (sites A and B) were selected to assess the potential of combined uranium series-electron spin resonance (US-ESR) dating of Early Pleistocene sites. Although the US-ESR results of the first outcrop showed a large scatter between the three teeth, the mean age of 1.37 ± 0.24 Ma can be considered a reasonable age estimate for Venta Micena. The mean ESR age of 0.62 ± 0.03 Ma obtained for site B seems to be a severe underestimation when compared with the independent age control. This underestimation is attributed to a relative recent U-mobilization event that led to some U-leaching. The results show that any ESR age calculations of old samples are extremely sensitive to variations in the measured 230Th/234U ratios in dental tissues. Although the results demonstrate that ESR can in principle be applied to Early Pleistocene sites, they also reveal the complexity of dating such old teeth. It is necessary to continue research in several directions, such as study of the behaviour of ESR signals in old teeth and understanding recent U-mobilization processes, to improve the reliability of the combined US-ESR dating method applied to Early Pleistocene times, a period for which the number of available numerical dating techniques is very limited. (authors)

  14. Lethal interpersonal violence in the Middle Pleistocene.

    Sala, Nohemi; Arsuaga, Juan Luis; Pantoja-Pérez, Ana; Pablos, Adrián; Martínez, Ignacio; Quam, Rolf M; Gómez-Olivencia, Asier; Bermúdez de Castro, José María; Carbonell, Eudald

    2015-01-01

    Evidence of interpersonal violence has been documented previously in Pleistocene members of the genus Homo, but only very rarely has this been posited as the possible manner of death. Here we report the earliest evidence of lethal interpersonal violence in the hominin fossil record. Cranium 17 recovered from the Sima de los Huesos Middle Pleistocene site shows two clear perimortem depression fractures on the frontal bone, interpreted as being produced by two episodes of localized blunt force trauma. The type of injuries, their location, the strong similarity of the fractures in shape and size, and the different orientations and implied trajectories of the two fractures suggest they were produced with the same object in face-to-face interpersonal conflict. Given that either of the two traumatic events was likely lethal, the presence of multiple blows implies an intention to kill. This finding shows that the lethal interpersonal violence is an ancient human behavior and has important implications for the accumulation of bodies at the site, supporting an anthropic origin. PMID:26018668

  15. Lethal interpersonal violence in the Middle Pleistocene.

    Nohemi Sala

    Full Text Available Evidence of interpersonal violence has been documented previously in Pleistocene members of the genus Homo, but only very rarely has this been posited as the possible manner of death. Here we report the earliest evidence of lethal interpersonal violence in the hominin fossil record. Cranium 17 recovered from the Sima de los Huesos Middle Pleistocene site shows two clear perimortem depression fractures on the frontal bone, interpreted as being produced by two episodes of localized blunt force trauma. The type of injuries, their location, the strong similarity of the fractures in shape and size, and the different orientations and implied trajectories of the two fractures suggest they were produced with the same object in face-to-face interpersonal conflict. Given that either of the two traumatic events was likely lethal, the presence of multiple blows implies an intention to kill. This finding shows that the lethal interpersonal violence is an ancient human behavior and has important implications for the accumulation of bodies at the site, supporting an anthropic origin.

  16. The Middle Pleistocene human tibia from Boxgrove.

    Stringer, C B; Trinkaus, E; Roberts, M B; Parfitt, S A; Macphail, R I

    1998-05-01

    The Boxgrove tibia was discovered in 1993, associated with Middle Pleistocene fauna, and Lower Palaeolithic archaeology. The sediments at Boxgrove were deposited during a temperate interglacial episode and ensuing cold stage. They thus represent a wide range of modes and environments of deposition. Archaeological remains have been excavated from all the major stratigraphic units, giving a continuity of occupation for this part of southern England over a 10(4) year timescale, through markedly changing climatic regimes. The stratigraphic, archaeological and sedimentological contexts of the tibia are described, as well as its preservation and morphology. Measurements are given, with discussion of reconstructed bone length, and stature estimates. Comparative measurements are provided for fossil and recent human samples: the large dimensions of its diaphysis place the Boxgrove tibia near or beyond the upper size limits of the comparative samples, but its reconstructed length and estimated stature are less exceptional. The elevated robusticity of the specimen indicates exceptional diaphyseal strength and/or cold adapted body proportions paralleling those of the Neanderthals. Disagreement about the taxonomy of Middle Pleistocene hominids and lack of comparable fossil material make a specific assignment for the Boxgrove tibia problematic. The tibia can only definitely be assigned to non-modern Homo sp., with possible further reference to Homo cf. heidelbergensis (Schoetensack, 1908) on temporal and geographic grounds, if the validity of that species is accepted. PMID:9614636

  17. Stratigraphy and Tectonics of Southeastern Serenitatis. Ph.D. Thesis

    Maxwell, T. A.

    1976-01-01

    Results of investigations of returned Apollo 17 samples, and Apollo 15 and 17 photographs have provided a broad data base on which to interpret the southeastern Serenitatis region of the moon. Although many of the pre-Apollo 17 mission interpretations remain valid, detailed mapping of this region and correlation with earth-based and orbital remote-sensing data have resulted in a revision of the local mare stratigraphy.

  18. Comparison of Mechanical and Fracture Stratigraphy between Failed Seal Analouges

    Petrie, Elizabeth S; Evans, James P

    2012-01-01

    A cap rock, or seal, provides a barrier to the migration of fluid or gas out of intended trap due to its low permeability, high capillary-entry pressure nature. The presence of discontinuities in seal lithologies affects both their mechanical and hydrogeologic properties; migration of fluids or gas through mm- to cm-scale discontinuity networks can lead to the failure of hydrocarbon traps or waste repositories. We examine the mechanical and fracture stratigraphy of Paleozoic and Mesozoic anal...

  19. Late Aptian-Albian of the Vocontian Basin (SE-France) and Albian of NE-Texas: Biostratigraphic and paleoceanographic implications by planktic foraminifera faunas

    Reichelt, Kerstin

    2005-01-01

    Planktic foraminifera fauna and carbon isotopes of the bulk rock have been investigated to compile a high resolution biostratigraphy for the Late Aptian to Late Albian in the Vocontian Basin (SE-France) and for the Middle and Late Albian in NE-Texas. A high resolution carbon isotope stratigraphy (CIS) has been established for the Albian of the Vocontian Basin, and partially correlated with sections in the eastern (ODP 547, Mazagan Plateau) and western (ODP 1052; Blake Nose Plateau) Atlantic a...

  20. MALACOLOGICAL RESPONSE TO PLEISTOCENE SEA-LEVEL CHANGE IN THE NORTHERN PO PLAIN, N. ITALY: DETAILED PALAEOENVIRONMENTAL RECONSTRUCTIONS FROM TWO LOMBARDIAN CORES

    DANIELE GIANOLLA

    2010-03-01

    Full Text Available The interdisciplinary study of two deep cores drilled in Pleistocene basin fill at Northern margin of Po Plain, has been integrated with qualitative and quantitative malacological analysis. The potential of quantitative malacological analysis, to refine results obtained from interdisciplinary studies, is here highlighted. The evolution of malacological assemblages has been recorded and correlated to the general regressive trend recognized all over the Po Basin. Lower Pleistocene marine deposits, found at core base (Jaramillo Subchron and older, were gradually replaced by transitional and continental deposits since latest early Pleistocene. Area was eventually covered by continental conglomerate deposits (“Ceppo” facies during middle-late Pleistocene. Within this general trend, regional significance of a major unconformity (“r” surface, related to onset of Pleistocene glacial cycle, is confirmed. However, as evidenced by malacology, the roughly synchronous onset of coarse clastic progradation did not result in a synchronous shift from marine to transitional and continental settings all over the study area, as an effect of inherited topography and other local factors. During marine sedimentation, fossil record allowed us to recognize a transgressive event, reliably correlated to Marine Isotope Stage 35. 

  1. A combined palaeomagnetic and environmental magnetic investigation of Late Glacial loess from the Middle Danube Basin (Süttö, Hungary)

    Rolf, Christian; Hambach, Ulrich; Novothny, Agnes; Schnepp, Elisabeth; Worm, Kathrin

    2010-05-01

    In July 2008 and in August 2009 sampling for palaeomagnetic and environmental magnetic research was carried out at a 20 m thick Upper Pleistocene loess-palaeosol sequence near Süttö (North Hungary) in order to establish a high resolution palaeomagnetic record. Aeolian dust was deposited worldwide during dry/cold periods of the recent geological past. Alternating environmental conditions (dry/cold; humid/warm) after deposition led to loess-paleosol sequences (LPSS) covering wide parts of the continents and providing high resolution archives of palaeoclimatic changes during the Pleistocene. LPSS cover more than 30% of the surface of Hungary. In order to establish an absolute chronology for late Quaternary deposits from Hungary, different loess-palaeosol sequences have been investigated by luminescence dating performed by the Leibniz Institute for Applied Geophysics (LIAG) in Hannover in collaboration with the Department of Physical Geography of the Eötvös Loránd University of Budapest. The objectives of our study are: firstly, to establish a palaeomagnetic directional record for additional, independent dating; secondly, to construct a palaeosol-loess stratigraphy based on variations of the magnetic susceptibility (MS) and other rock magnetic proxies with depth in order to reconstruct the palaeoclimatic evolution; thirdly, to build a relative palaeointensity record and to compare this record with the high resolution global palaeointensity stack GLOPIS 75 (Laj et al. 2004). During our first sampling campaign we took small cylinders and overlapping blocks. Based on the results of this campaign we collected samples with narrow spacing (1 cm) at the most interesting part of the profile. Most samples show a clear palaeomagnetic signal and magnetic cleaning (thermal or alternating field) yielded stable characteristic remanences with well defined palaeodirections. Thus, the profile at Süttö represents a succession of palaeodirections characterised mainly by normal

  2. Paleobotanical analysis of materials from fossil gopher burrows and upper pleistocene host deposits, the Kolyma River lower reaches

    Lopatina, D. A.; Zanina, O. G.

    2006-10-01

    The comparative analysis of palynomorphs and plant megafossils (fruits, seeds, twigs, leaves) in the Upper Pleistocene host sediments and materials filling in fossil burrows of gophers, their coprolites included, at the Duvannyi Yar, Stanchikovskii Yar and Zelenyi Mys sites of the Kolyma Lowland is carried out. Genera Salix, Lychnis, Silene, Draba, Potentilla, Larix, and families Poaceae, Polygonaceae, Cyperaceae, Compositae, and Leguminosae are determined among palynological remains and megafossils. Factors responsible for qualitative and quantitative differences in taxonomic compositions of palynological and megafossil assemblages are biological peculiarities of plants, different character of fossilization of palynomorphs and large plant remains, geographic conditions, different genesis of assemblages (allochthonous for microfossils and autochthonous for megafossils), and inadequately known morphology of certain spore and pollen taxa. The comprehensive paleobotanical analysis leads to the conclusion that the study region was occupied in the Late Pleistocene by plant communities of humid to somewhat dryer tundra with separate areas of pioneering and steppe vegetation.

  3. On the limits of using combined U-series/ESR method to date fossil teeth from two Early Pleistocene archaeological sites of the Orce area (Guadix-Baza basin, Spain)

    The combined U-series/electron spin resonance (ESR) dating method was applied to nine teeth from two Early Pleistocene archaeological sites located in the Orce area (Guadix-Baza Basin, Southern Spain): Fuente Nueva-3 (FN-3) and Barranco Leon (BL). The combination of bio-stratigraphy and magneto-stratigraphy places both sites between the Olduvai and Jaramillo sub-chrons (1.78-1.07 Ma). Our results highlight the difficulty of dating such old sites and point out the limits of the combined U-series/ ESR dating method based on the US model. We identified several sources of uncertainties that may lead to inaccurate age estimates. Seven samples could not be dated because the dental tissues had (230Th/234U) activity ratios higher than equilibrium, indicating that uranium had probably leached from these tissues. It was however possible to calculate numerical estimates for two of the teeth, both from FN-3. One yielded a Middle Pleistocene age that seems to be strongly underestimated; the other provided an age of 1.19±0.21 Ma, in agreement with data obtained from independent methods. The latter result gives encouragement that there are samples that can be used for routine dating of old sites. (authors)

  4. Discontinuity surfaces and event stratigraphy of Okha Shell Limestone Member: Implications for Holocene sea level changes, western India

    Uday Bhonde; Bhawanisingh G Desai

    2011-08-01

    The Okha Shell Limestone Member of Chaya Formation is the coarse grained, shell rich deposit commonly recognized as the beach rocks. It has been age bracketed between Late Pleistocene and Holocene. Late Quaternary sea level changes have been studied with beach rocks along the Saurashtra coastal region. The present study has been carried out in the Okhamandal area of the Saurashtra peninsula especially on the Okha Shell Limestone Member as exposed at various locations along the coast from north to south. Temporal and spatial correlations of the observations have revealed three events in the Okha Shell Limestone Member of Chaya Formation that are correlated laterally. The events show depositional breaks represented by discontinuity surfaces, the taphofacies varieties and ichnological variations. The present study in the context of available geochrnological data of the region suggests a prominent depositional break representing low sea level stand (regression) during an Early Holocene during the deposition of Okha Shell Limestone Member.

  5. Les calcaires urgoniens du domaine delphino-helvétique (Chaînes subalpines septentrionales de Haute-Savoie, France) : sédimentologie, stratigraphie séquentielle et biostratigraphie

    Trabold, Günter

    1995-01-01

    Part 1: The aim of this study is to delineate the paleoenvironmental and paleogeographical evolution of Late Hauterivian - Early Aptian shelf deposits developed on the European passive margin of the Iigurian Tethys. The study was focused on the sedimentological, sequence stratigraphical and biostratigraphical development of the Urgonian limestones. Based on the investigation of numerous stratigraphie sections in the northern Subalpine Chains (Western Alps, SE-France) the shelf can be divided ...

  6. A new Late Ordovician erratic anthaspidellid sponge (Porifera) originating from Baltica

    Rhebergen, F.

    2014-01-01

    The new anthaspidellid taxon Brevaspidella dispersa is erected for specimens recovered from the Late Ordovician sponge assemblages of the island of Gotland, Sweden and the Dutch-German border region. In the latter area, they are collected from Early Pleistocene fluvial deposits of the Baltic River S

  7. A new otter from the Early Pleistocene of Pantalla (Italy), with remarks on the evolutionary history of Mediterranean Quaternary Lutrinae (Carnivora, Mustelidae)

    Cherin, Marco; Iurino, Dawid Adam; Willemsen, Gerard; Carnevale, Giorgio

    2016-03-01

    Here we describe a well-preserved sub-complete lutrine cranium from the late Villafranchian (Early Pleistocene) of Pantalla (Italy) and we assign it to the new taxon Lutraeximia umbra, gen. et sp. nov. The new genus Lutraeximia is characterized by a relatively short and large cranium, with a peculiar shape of the postorbital area and a short and vertical muzzle in lateral view. We refer to the same genus the partially complete skeleton of Lutra trinacriae from the Middle-Late Pleistocene of Sicily. Lutraeximia umbra was a medium-large otter (predicted body mass larger than 13.5 kg) with a unique combination of characters in the upper dentition. A phylogenetic analysis based on craniodental characters places Lutraeximia umbra in a monophyletic clade including the living Lutrogale perspicillata plus the extinct Lutrogale cretensis and three Pleistocene otters from Italy: Sardolutra ichnusae and the sister taxa Lutraeximia trinacriae and Lutraeximia umbra. The recognition of this clade evidences the broad diversity of peri-Mediterranean Lutrinae during the Pleistocene.

  8. Male strategies and Plio-Pleistocene archaeology.

    O'Connell, J F; Hawkes, K; Lupo, K D; Blurton Jones, N G

    2002-12-01

    Archaeological data are frequently cited in support of the idea that big game hunting drove the evolution of early Homo, mainly through its role in offspring provisioning. This argument has been disputed on two grounds: (1) ethnographic observations on modern foragers show that although hunting may contribute a large fraction of the overall diet, it is an unreliable day-to-day food source, pursued more for status than subsistence; (2) archaeological evidence from the Plio-Pleistocene, coincident with the emergence of Homo can be read to reflect low-yield scavenging, not hunting. Our review of the archaeology yields results consistent with these critiques: (1) early humans acquired large-bodied ungulates primarily by aggressive scavenging, not hunting; (2) meat was consumed at or near the point of acquisition, not at home bases, as the hunting hypothesis requires; (3) carcasses were taken at highly variable rates and in varying degrees of completeness, making meat from big game an even less reliable food source than it is among modern foragers. Collectively, Plio-Pleistocene site location and assemblage composition are consistent with the hypothesis that large carcasses were taken not for purposes of provisioning, but in the context of competitive male displays. Even if meat were acquired more reliably than the archaeology indicates, its consumption cannot account for the significant changes in life history now seen to distinguish early humans from ancestral australopiths. The coincidence between the earliest dates for Homo ergaster and an increase in the archaeological visibility of meat eating that many find so provocative instead reflects: (1) changes in the structure of the environment that concentrated scavenging opportunities in space, making evidence of their pursuit more obvious to archaeologists; (2) H. ergaster's larger body size (itself a consequence of other factors), which improved its ability at interference competition. PMID:12473486

  9. Investigations on alluvial deposits through borehole stratigraphy, radiocarbon dating and passive seismic technique (Carnic Alps, NE Italy)

    Viero, Alessia; Marchi, Lorenzo; Cavalli, Marco; Crema, Stefano; Fontana, Alessandro; Mozzi, Paolo; Venturini, Corrado

    2016-04-01

    Alluvial sediment investigations provide fundamental tools to infer the processes that control geomorphological evolution of mountain environments. By analyzing sediment stratigraphy in depth, it is possible to retrieve the source, the geology, the time of deposition, the relative distance travelled by material as well as to distinguish among different type of transport (i.e., gravitational, fluvial or glacial). In this work, we present a combination of log stratigraphy, radiocarbon dating and geophysical surveys carried out on the valley floor of the But River (Carnic Alps, North East Italy). The But River basin drains an area of 326 km2 with a range in elevation from 2769 to 323 m a.s.l.; the bedrock mainly consists of carbonates and quartz arenites with minor inclusions of effusive rocks. After Pleistocene the gravitational deposits from mountain slopes have impounded the But River several times. In particular, we analyzed a sector of the upper portion of the But valley close to the confluence of the Moscardo Torrent, frequently affected by debris flows. A borehole was drilled in the But River floodplain, at the intersection with the Moscardo Torrent alluvial fan, down to a depth of 80 m. The analysis of the core samples allowed discerning three sedimentary levels rich in clay and organic materials, which testify the presence of small dam lakes, originated from the Moscardo debris-flow deposits. Three samples of wood and plant debris were collected from 13, 14 and 23 m of depth, respectively. They were analyzed through radiocarbon dating in order to determine the age of the lakes and, thus, to infer the activity of the debris flows building the Moscardo cone. The calibrated ages of the 3 samples are close to the younger limit of the radiocarbon method indicating a fast aggradation of the valley floor, starting from a period ranging between 1450 - 1632 AD. Historical maps and documents confirm the presence of the lakes until 19th century and they permit to assess

  10. Miocene to Pleistocene osmium isotopic records of the Mediterranean sediments

    Kuroda, Junichiro; Jiménez-Espejo, Francisco J.; Nozaki, Tatsuo; Gennari, Rocco; Lugli, Stefano; Manzi, Vinicio; Roveri, Marco; Flecker, Rachel; Sierro, Francisco J.; Yoshimura, Toshihiro; Suzuki, Katsuhiko; Ohkouchi, Naohiko

    2016-01-01

    In the late Miocene the Mediterranean Sea experienced a salinity crisis and thick sequences of evaporites precipitated across the deep and marginal basins. In this study we report Os isotopic records from Deep Sea Drilling Project and Ocean Drilling Project cores in the Mediterranean: the Balearic Sea (Site 372), the Tyrrhenian Sea (Site 654), the Ionian Basin (Site 374), and the Florence Rise (Sites 375-376), as well as Integrated Ocean Drilling Project Site U1387 in Gulf of Cadiz, North Atlantic. Pliocene-Pleistocene sediments at all sites show 187Os/188Os values close to that of the coeval ocean water, indicating that the Mediterranean was connected to the North Atlantic. Evaporitic sediments deposited during the latest Miocene, however, have 187Os/188Os values significantly lower than coeval ocean water values. The offset of the Mediterranean evaporite 187Os/188Os is attributed to limited exchange with the North Atlantic during the Messinian salinity crisis. The source of unradiogenic Os is likely to be weathering of ultramafic rocks (ophiolites) cropping out in the Mediterranean's drainage basins. Based on a box model we estimated the amount of unradiogenic Os and the Atlantic-Mediterranean exchange rate to explain this offset. Os isotopic ratios of the pre-evaporite sediments in the western Mediterranean are almost identical to that of the coeval ocean water. In contrast, equivalent sediments from the Florence Rise have significantly lower 187Os/188Os values. The offset in the Os isotopic ratio on the Florence Rise is attributed either to limited water exchange between eastern and western Mediterranean or to local effects associated with exhumation of the Troodos ophiolites (Cyprus).

  11. Abundance and size variation of Globorotalia menardii in the Northeastern Indian Ocean during the Late Quaternary

    Bhonsale, S.; Saraswat, R.

    reconstructions. Palaeogeogra., Palaeoclimatol., Palaeoecol. 160, 193-212. Kennett, J.P., Huddlestun, P., 1972. Late Pleistocene paleoclimatology, foraminiferal biostratigraphy and tephrochronology, western Gulf of Mexico. Quat. Res. 2, 3-9. Knappertsbusch, M... monsoon 2001. Deep-Sea Res. 50, 881-896. Malmgren, B., Healy-Williams, N., 1978. Variation in test diameter of Orbulina universa in the paleoclimatology of the late Quaternary of the Gulf of Mexico. Palaeogeogra., Palaeoclimatol., Palaeoecol. 25, 235...

  12. Pliocene and pleistocene volcanism in Southern Kyushu

    Southern Kyushu has been the site of intense volcanism at least since Pliocene time. One of the characteristics is the prevalence of large scale pyroclastic flow eruption, most of which originated from the volcano-tectonic depression now occupied by Kagoshima Bay. The deposits of these pyroclastic flows cover wide areas, serving as excellent stratigraphic marker horizons, but the radiometric age of the volcanic rocks in the area has been hardly available so far. A sample of Isaku pyroclastic flow was taken from an abandoned quarry. Ushine andesite, Fumoto pyroclastic flow, Ushine basalt and Ushine rhyolite were collected from a 300 m high cliff toward the top from the bottom. Kiyoura horn-blende andesite was collected from the southeastern foot of Yaeyama. K-Ar age was determined for these rocks. It was indicated that from 2 to 3 Ma (i.e., million years) ago, large scale pyroclastic eruption had taken place in the northern part of Kagoshima Bay, and extensive andesitic to basaltic volcanism occurred in both Ushine and Yaeyama areas. The establishment of the volcanic stratigraphy in the areas must await until more radiometric age determination becomes available. (Kako, I.)

  13. Plio-Pleistocene changes in the vegetation of central North Africa

    Castaneda, I. S.; Phu, V.; Urann, B.

    2013-12-01

    The area of central North Africa (including the Sahara and the Sahel) is sensitive to migrations of the intertropical rainbelt and has experienced dramatic, and possibly abrupt, shifts between wet and arid conditions in the past. For example, during the humid period of the early Holocene, the region that is presently the Sahara desert was vegetated and contained permanent lakes, and was occupied by human populations (e.g. Kuper and Kröpelin, 2006). In this study, we investigate the hydrology of central North Africa during the Plio-Pleistocene (4-0.5 Ma), a period during which a number of key steps in hominin evolution occurred. ODP site 660 is located in the tropical NE Atlantic Ocean (offshore West Africa) and receives dust from central North Africa, which is transported offshore by the African Easterly Jet. Plant leaf waxes (n-alkanes) contained in this dust provide information on the type of vegetation present , which in turn, can be used to examine hydrological variability because in tropical Africa the large scale distribution of vegetation utilizing the C3 (mainly trees) vs. C4 (grasses and warm season sedges) photosynthetic pathways mainly depends on aridity (precipitation) (e.g. Schefuss et al., 2003). Here, we examine the carbon (δ13C) and deuterium (δD) isotopic composition of plant leaf waxes, proxies for vegetation type (C3 vs. C4 plants) and precipitation amount, respectively. We also examine sea surface temperature variability using the alkenone Uk'37 Index as several studies have demonstrated close ties between sea surface temperature variability and hydrological conditions in N Africa during the late Pleistocene and Holocene. Results of this study further support a close link between SST and hydrological conditions in the Sahel during the past 4 Ma while also highlighting regional differences in aridity between Plio-Pleistocene records of western, eastern and southern Africa.

  14. New data on Pleistocene and Holocene herpetofauna of Marie Galante (Blanchard Cave, Guadeloupe Islands, French West Indies): Insular faunal turnover and human impact

    Bailon, S.; Bochaton, C.; Lenoble, A.

    2015-11-01

    This work presents the herpetofaunal remains collected from Blanchard Cave (Marie-Galante, Guadeloupe Archipelago). This site has yielded the oldest stratigraphic layers (around 40,000 BP) of the island, along with data concerning the herpetofaunal biodiversity of the island from the Late Pleistocene to pre-Columbian and modern times. The study of these fossil remains reveals the presence of at least 11 amphibian and squamata taxa (Eleutherodactylus cf. martinicensis, Iguana sp., Anolis ferreus, Leiocephalus cf. cuneus, Thecadactylus cf. rapicauda, cf. Capitellum mariagalantae, Ameiva sp., cf. Antillotyphlops, Boa sp., Alsophis sp. and Colubridae sp. 2) during the Late Pleistocene and Holocene on Marie-Galante Island and provides new evidence concerning extinction times and the introduced or native status of taxa. This study also reveals that this bone assemblage is the result of diverse accumulation processes and provides new morphological data on the past herpetofauna of Marie-Galante.

  15. Pleistocene fish otoliths from the Mediterranean Basin: a synthesis

    Girone, A.; Nolf, D.; Cappetta, H

    2006-01-01

    An overview of upper pPliocene and Pleistocene otolith assemblages is compiled on the basis of both literature data and newly collected material from several sections located mainly in southern Italy. One hundred and five taxa are listed. Additional comments are provided for taxa subject to discussion. The composition and affinities of the Mediterranean Pleistocene otolith associations (consisting mainly of deep sea fishes) is checked against the available data for Pre-Messinian, Pliocene, an...

  16. Construction and maintenance of the Ganges-Brahmaputra-Meghna delta: linking process, morphology, and stratigraphy.

    Wilson, Carol A; Goodbred, Steven L

    2015-01-01

    We present a review of the processes, morphology, and stratigraphy of the Ganges-Brahmaputra-Meghna delta (GBMD), including insights gained from detailed elevation data. The review shows that the GBMD is best characterized as a composite system, with different regions having morphologic and stratigraphic attributes of an upland fluvial fan delta; a lowland, backwater-reach delta; a downdrift tidal delta plain; and an offshore subaqueous-delta clinoform. These distinct areas of upland and lowland fluvial reaches and tidal dominance vary in time and space, and we distinguish late-Holocene phases of delta construction, maintenance, and decline similar to delta-lobe cycling in other systems. The overall stability of the GBMD landform, relative to many deltas, reflects the efficient, widespread dispersal of sediment by the large monsoon discharge and high-energy tides that affect this region. However, we do identify portions of the delta that are in decline and losing elevation relative to sea level owing to insufficient sediment delivery. These areas, some of which are well inland of the coast, represent those most at risk to the continued effect of sea-level rise. PMID:25251271

  17. Structural influences on seismic stratigraphy of Nias forearc basin, west of central Sumatra

    Matson, R.G.; Moore, G.F.

    1988-02-01

    The Nias forearc basin is a 250-km long, 100-km wide bathyal depression located between the mainland of west-central Sumatra and the island of Nias. A grid of multichannel reflection seismic data covering the basin and adjacent shelves was used to map Neogene structure and to delineate the Neogene seismic stratigraphy. Six major structural features, including the continental margin, strike-slip faults traversing the forearc, and uplifts within the accretionary wedge, were mapped, while 11 seismic sequences were identified within Neogene reflectors. Positive correlations between the structure and seismic facies distributions indicate structure has influenced subsidence and depositional patterns through the developmental history of the basin. From a developmental standpoint, the Nias forearc basin can be subdivided into two smaller basins, the Singkel basin to the north and the Pini basin to the south. During the Miocene and early Pliocene, distinct facies distributions indicate that these two basins developed independently of each other. Subsidence in the Singkel basis was initiated between two parallel strike-slip faults that traverse the forearc. The geometry of the Pini basin, on the other hand, was controlled by the local character of the continental margin and by the uplift of the developing accretionary wedge. In the late Pliocene, a more unified facies distribution across the study area indicates subsidence of a more regional character and an increased regional structural influence over the entire Nias basin area.

  18. Study on quaternary stratigraphy and environmental changes in South Sea, Korea

    Chang, Jeong-Hae; Lee, Chi-Won; Kim, Sung-Pil [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)

    1999-12-01

    According to interpretation of seismic profiles crossing the drilled sites, there are five sequences, namely Unit I, Unit II, Unit III, Unit IV and Unit V from bottom, separable by a reflector with good lateral continuity. If we apply the conception of sequential stratigraphy to the sea level fluctuation caused depositional processes, based on the results of seismic profiles, it will be possible to figure out the late Quaternary depositional processes in the context of sea level changes. According to the sedimentological and seismic stratigraphic analysis, most of SSDP sites showed transgression and regression sequences. Chemical analyses of elements for the sediment samples of SSDP-102 core exhibit the geochemical factors which may influenced the sedimentary environments of the study area. The lower-most sedimentary sequence Unit III can be interpreted as an environment which was influenced dominantly by stronger chemical weathering under a semi-fresh water environment. Based on predominance of carbonate-originated Ca in the homogeneous mud sequence, a high productive surface water along with transgression may have controlled the upper-most sedimentary sequence Unit I. Scatter diagram represents oxygen and carbon isotopic values of benthic foraminifera (Asterorotalia concinna) which is analyzed. All 61 points has value between +1 and -1. If isotopic values of selected benthic foraminifera are equilibrium with surrounding values. These distributions indicate transitional between coastal environment affected by fresh water and open marine environment. (author). 24 refs., 8 tabs., 25 figs.

  19. Stratigraphy and Observations of Nepthys Mons Quadrangle (V54), Venus

    Bridges, N. T.

    2001-01-01

    Initial mapping has begun in Venus' Nepthys Mons Quadrangle (V54, 300-330 deg. E, 25-50 deg. S). Major research areas addressed are how the styles of volcanism and tectonism have changed with time, the evolution of shield volcanoes, the evolution of coronae, the characteristics of plains volcanism, and what these observations tell us about the general geologic history of Venus. Reported here is a preliminary general stratigraphy and several intriguing findings. Additional information is contained in the original extended abstract.

  20. The Stratigraphy and Evolution of the Lunar Crust

    McCallum, I. Stewart

    1998-01-01

    Reconstruction of stratigraphic relationships in the ancient lunar crust has proved to be a formidable task. The intense bombardment during the first 700 m.y. of lunar history has severely perturbed the original stratigraphy and destroyed the primary textures of all but a few nonmare rocks. However, a knowledge of the crustal stratigraphy as it existed prior to the cataclysmic bombardment about 3.9 Ga is essential to test the major models proposed for crustal origin, i.e., crystal fractionation in a global magmasphere or serial magmatism in a large number of smaller bodies. Despite the large difference in scale implicit in these two models, both require an efficient separation of plagioclase and mafic minerals to form the anorthositic crust and the mafic mantle. Despite the havoc wreaked by the large body impactors, these same impact processes have brought to the lunar surface crystalline samples derived from at least the upper half of the lunar crust, thereby providing an opportunity to reconstruct the stratigraphy in areas sampled by the Apollo missions. As noted, ejecta from the large multiring basins are dominantly, or even exclusively, of crustal origin. Given the most recent determinations of crustal thicknesses, this implies an upper limit to the depth of excavation of about 60 km. Of all the lunar samples studied, a small set has been recognized as "pristine", and within this pristine group, a small fraction have retained some vestiges of primary features formed during the earliest stages of crystallization or recrystallization prior to 4.0 Ga. We have examined a number of these samples that have retained some record of primary crystallization to deduce thermal histories from an analysis of structural, textural, and compositional features in minerals from these samples. Specifically, by quantitative modeling of (1) the growth rate and development of compositional profiles of exsolution lamellae in pyroxenes and (2) the rate of Fe-Mg ordering in

  1. An Outline of the Quaternary Stratigraphy of Austria

    Dirk van Husen; Jürgen M. Reitner

    2011-01-01

    Es wird ein Überblick über die in Österreich verwendete Quartär-Stratigraphie gegeben. Die stratigraphische Gliederung der kartierbaren Sedimenteinheiten basiert teilweise auf Kriterien der Lithostratigraphie (lithologischer Eigenschaften) und jenen der Allostratigraphie (z.B. Diskonitinuitäten). Für das Altpleistozän (2.58–0.78 Ma) fehlen bis jetzt Spuren einer Vergletscherung. Die wenigen und isolierten Sedimentvorkommen belegen fluviatile Akkumulation und Lössablagerung in der Umgebung der...

  2. Late Quaternary kinematics, slip-rate and segmentation of a major Cordillera-parallel transcurrent fault: The Cayambe-Afiladores-Sibundoy system, NW South America

    Tibaldi, A.; Università di Milano-Bicocca; Rovida, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia; Corazzato, C.; Università di Milano-Bicocca

    2007-01-01

    We describe the recent activity of the Cayambe-Afiladores-Sibundoy Fault (CASF) and recognise it as one of the major potential active structures of northwestern South America, based on field observations, stereoscopic aerial photos of offset late Pleistocene-Holocene deposits and landforms, and crustal seismic activity. The CASF runs for at least 270 km along the sub-Andean zone of northern Ecuador and southern Colombia. We measured systematic latest Pleistocene-Holocene right-lateral strike-...

  3. Pleistocene megafaunal interaction networks became more vulnerable after human arrival.

    Pires, Mathias M; Koch, Paul L; Fariña, Richard A; de Aguiar, Marcus A M; dos Reis, Sérgio F; Guimarães, Paulo R

    2015-09-01

    The end of the Pleistocene was marked by the extinction of almost all large land mammals worldwide except in Africa. Although the debate on Pleistocene extinctions has focused on the roles of climate change and humans, the impact of perturbations depends on properties of ecological communities, such as species composition and the organization of ecological interactions. Here, we combined palaeoecological and ecological data, food-web models and community stability analysis to investigate if differences between Pleistocene and modern mammalian assemblages help us understand why the megafauna died out in the Americas while persisting in Africa. We show Pleistocene and modern assemblages share similar network topology, but differences in richness and body size distributions made Pleistocene communities significantly more vulnerable to the effects of human arrival. The structural changes promoted by humans in Pleistocene networks would have increased the likelihood of unstable dynamics, which may favour extinction cascades in communities facing extrinsic perturbations. Our findings suggest that the basic aspects of the organization of ecological communities may have played an important role in major extinction events in the past. Knowledge of community-level properties and their consequences to dynamics may be critical to understand past and future extinctions. PMID:26336175

  4. Climate-Ice Sheet Interactions through the Pliocene-Pleistocene: Preliminary Results from IODP Expedition 341 (Gulf of Alaska)

    Müller, J.; McClymont, E.; Sanchez Montes, M. L.; Moy, C. M.; Romero, O. E.; Lloyd, J. M.

    2014-12-01

    Since the Pliocene, global climate history is distinguished by the transition into a colder world, dominated by the onset and intensification of major Northern Hemisphere glaciations which have also changed in their duration and intensity. Potential drivers for these events include falling atmospheric CO2, progressive sub-glacial erosion, tectonic uplift, and associated feedbacks. At present, isolating climate as the driver of evolving continental ice volume since the Pliocene is hindered by the limited long term data sets which directly link climate changes to evidence for ice-sheet advance/retreat, erosion, and tectonic evolution over million year timescales. IODP Expedition 341 drilled a cross-margin transect in the Gulf of Alaska from ice-proximal sites on the continental shelf to distal sites in the deep Pacific. This study focuses on the distal site (Site U1417, c.4190 m water depth) which contains variable biogenic and terrigenous contributions, and evidence for deposition through pelagic, mass movement and glacial processes. Our aim is to investigate links between north-east Pacific paleoceanography and the history of the north-west Cordilleran ice sheet, neither of which are fully understood given limited data pre-dating the Last Glacial Maximum. We reconstruct SSTs during the mid-Pliocene, Plio-Pleistocene Transition (PPT) and mid-Pleistocene transition (MPT) using the UK37' index. We consider the interaction between SSTs and primary production by examining the absolute and relative abundances of plankton biomarkers (e.g. for haptophytes, diatoms and dinoflagellates), carbon/nitrogen ratios, stable isotopes (δ13C, δ15N) and diatom assemblages. Links between these climatic events and the north-west Cordilleran ice-sheet advance/retreat history are initially made using shipboard stratigraphy; emerging data sets on ice-rafting from members of the Expedition 341 Scientific Party will refine these relationships.

  5. The legacy of the Pleistocene megafauna extinctions on nutrient availability in Amazonia

    Doughty, Christopher E.; Wolf, Adam; Malhi, Yadvinder

    2013-09-01

    In the late Pleistocene, 97 genera of large animals went extinct, concentrated in the Americas and Australia. These extinctions had significant effects on ecosystem structure, seed dispersal and land surface albedo. However, the impact of this dramatic extinction on ecosystem nutrient biogeochemistry, through the lateral transport of dung and bodies, has never been explored. Here we analyse this process using a novel mathematical framework that analyses this lateral transport as a diffusion-like process, and we demonstrate that large animals play a disproportionately large role in the horizontal transfer of nutrients across landscapes. For example, we estimate that the extinction of the Amazonian megafauna decreased the lateral flux of the limiting nutrient phosphorus by more than 98%, with similar, though less extreme, decreases in all continents outside of Africa. This resulted in strong decreases in phosphorus availability in eastern Amazonia away from fertile floodplains, a decline which may still be ongoing. The current P limitation in the Amazon basin may be partially a relic of an ecosystem without the functional connectivity it once had. We argue that the Pleistocene megafauna extinctions resulted in large and ongoing disruptions to terrestrial biogeochemical cycling at continental scales and increased nutrient heterogeneity globally.

  6. The carnivore remains from the Sima de los Huesos Middle Pleistocene site (Sierra de Atapuerca, Spain).

    García, N; Arsuaga, J L; Torres, T

    1997-01-01

    Remains of carnivores from the Sima de los Huesos site representing at least 158 adult individuals of a primitive (i.e., not very speleoid) form of Ursus deningeri Von Reichenau 1906, have been recovered through the 1995 field season. These new finds extend our knowledge of this group in the Sierra de Atapuerca Middle Pleistocene. Material previously classified as Cuoninae indet, is now assigned to Canis lupus and a third metatarsal assigned in 1987 to Panthera of gombaszoegensis, is in our opinion only attributable to Panthera sp. The family Mustelidae is added to the faunal list and includes Martes sp. and a smaller species. The presence of Panthera leo cf. fossilis, Lynx pardina spelaea and Felis silvestris, is confirmed. The presence of a not very speloid Ursus deningeri, together with the rest of the carnivore assemblage, points to a not very late Middle Pleistocene age, i.e., oxygen isotope stage 7 or older. Relative frequencies of skeletal elements for the bear and fox samples are without major biases. The age structure of the bear sample, based on dental wear stages, does not follow the typical hibernation mortality profile and resembles a catastrophic profile. The site was not a natal or refuge den. The hypothesis that the site was a natural trap is the most plausible. If the Sima de los Huesos functioned as a natural trap (without an egress out), the human accumulation cannot be attributed to carnivore: activities and must be explained differently. PMID:9300340

  7. Complete mitochondrial genome sequence of a Middle Pleistocene cave bear reconstructed from ultrashort DNA fragments.

    Dabney, Jesse; Knapp, Michael; Glocke, Isabelle; Gansauge, Marie-Theres; Weihmann, Antje; Nickel, Birgit; Valdiosera, Cristina; García, Nuria; Pääbo, Svante; Arsuaga, Juan-Luis; Meyer, Matthias

    2013-09-24

    Although an inverse relationship is expected in ancient DNA samples between the number of surviving DNA fragments and their length, ancient DNA sequencing libraries are strikingly deficient in molecules shorter than 40 bp. We find that a loss of short molecules can occur during DNA extraction and present an improved silica-based extraction protocol that enables their efficient retrieval. In combination with single-stranded DNA library preparation, this method enabled us to reconstruct the mitochondrial genome sequence from a Middle Pleistocene cave bear (Ursus deningeri) bone excavated at Sima de los Huesos in the Sierra de Atapuerca, Spain. Phylogenetic reconstructions indicate that the U. deningeri sequence forms an early diverging sister lineage to all Western European Late Pleistocene cave bears. Our results prove that authentic ancient DNA can be preserved for hundreds of thousand years outside of permafrost. Moreover, the techniques presented enable the retrieval of phylogenetically informative sequences from samples in which virtually all DNA is diminished to fragments shorter than 50 bp. PMID:24019490

  8. Nuclear DNA sequences from the Middle Pleistocene Sima de los Huesos hominins.

    Meyer, Matthias; Arsuaga, Juan-Luis; de Filippo, Cesare; Nagel, Sarah; Aximu-Petri, Ayinuer; Nickel, Birgit; Martínez, Ignacio; Gracia, Ana; Bermúdez de Castro, José María; Carbonell, Eudald; Viola, Bence; Kelso, Janet; Prüfer, Kay; Pääbo, Svante

    2016-03-24

    A unique assemblage of 28 hominin individuals, found in Sima de los Huesos in the Sierra de Atapuerca in Spain, has recently been dated to approximately 430,000 years ago. An interesting question is how these Middle Pleistocene hominins were related to those who lived in the Late Pleistocene epoch, in particular to Neanderthals in western Eurasia and to Denisovans, a sister group of Neanderthals so far known only from southern Siberia. While the Sima de los Huesos hominins share some derived morphological features with Neanderthals, the mitochondrial genome retrieved from one individual from Sima de los Huesos is more closely related to the mitochondrial DNA of Denisovans than to that of Neanderthals. However, since the mitochondrial DNA does not reveal the full picture of relationships among populations, we have investigated DNA preservation in several individuals found at Sima de los Huesos. Here we recover nuclear DNA sequences from two specimens, which show that the Sima de los Huesos hominins were related to Neanderthals rather than to Denisovans, indicating that the population divergence between Neanderthals and Denisovans predates 430,000 years ago. A mitochondrial DNA recovered from one of the specimens shares the previously described relationship to Denisovan mitochondrial DNAs, suggesting, among other possibilities, that the mitochondrial DNA gene pool of Neanderthals turned over later in their history. PMID:26976447

  9. Evolution, systematics, and phylogeography of pleistocene horses in the new world: a molecular perspective.

    2005-08-01

    Full Text Available The rich fossil record of horses has made them a classic example of evolutionary processes. However, while the overall picture of equid evolution is well known, the details are surprisingly poorly understood, especially for the later Pliocene and Pleistocene, c. 3 million to 0.01 million years (Ma ago, and nowhere more so than in the Americas. There is no consensus on the number of equid species or even the number of lineages that existed in these continents. Likewise, the origin of the endemic South American genus Hippidion is unresolved, as is the phylogenetic position of the "stilt-legged" horses of North America. Using ancient DNA sequences, we show that, in contrast to current models based on morphology and a recent genetic study, Hippidion was phylogenetically close to the caballine (true horses, with origins considerably more recent than the currently accepted date of c. 10 Ma. Furthermore, we show that stilt-legged horses, commonly regarded as Old World migrants related to the hemionid asses of Asia, were in fact an endemic North American lineage. Finally, our data suggest that there were fewer horse species in late Pleistocene North America than have been named on morphological grounds. Both caballine and stilt-legged lineages may each have comprised a single, wide-ranging species.

  10. Using hydrogeochemical methods to evaluate complex quaternary subsurface stratigraphy Block Island, Rhode Island, USA

    Veeger, A.I.; Stone, B.D.

    1996-01-01

    One of the major problems in Hydrogeologic investigations of glaciated regions is the determination of complex stratigraphic relationships in the subsurface where insufficient information is available from drilling and geophysical records. In this paper, chemical characteristics of groundwater were used to identify stratigraphic changes in glacial deposits that were previously inferred on Block Island, Rhode Island, USA, an emergent remnant of the late Wisconsinan terminal moraine, located approximately 16 km south of the Rhode Island mainland. Two chemically distinct water types are recognized on the island: 1) high-iron, characterized by dissolved silica levels in excess of 20 mg/L, bicarbonate greater than 30 mg/L and dissolved iron ranging from 1-20 mg/L; and 2) low-iron, characterized by dissolved silica levels below 16 mg/L, bicarbonate less than 30 mg/L, and less than 0.3 mg/L dissolved iron. The spatial distribution of iron-bearing minerals and organic matter and the resulting redox conditions are believed to control the occurrence of highiron groundwater. The high-iron waters occur almost exclusively in the eastern half of the island and appear to coincide with the presence of allochthonous blocks of Cretaceous-age coastal-plain sediments that were incorporated into Pleistocene-age deposits derived from the Narragansett Bay-Buzzard's Bay lobe of the Late Wisconsinan Laurentide ice sheet. The low-iron waters occur in the western half of the island, where the occurrence of these Cretaceous-age blocks is rare and the sediments are attributed to a sublobe of the Hudson-Champlain lobe of the Late Wisconsinan ice sheet.

  11. Stratigraphy and formation of clays, sulfates, and hydrated silica within a depression in Coprates Catena, Mars

    Weitz, Catherine M.; Bishop, Janice L.

    2016-05-01

    We investigate the morphology, mineralogy, and stratigraphy of light-toned layered deposits within a trough of Coprates Catena, centered at -15°N, 300°E. One of the deposits in the eastern portion of the trough contains numerous hydrated minerals, including Al-phyllosilicates, Fe/Mg-phyllosilicates, hydrated silica, hydrated sulfates, jarosite and acid alteration products characterized by a spectral doublet between 2.2 and 2.3 µm, and weakly hydrated materials. The Al-phyllosilicates are observed both stratigraphically above and below the Fe/Mg-phyllosilicate unit, which is a rare and perhaps unique association on Mars. Most of the western light-toned layered deposit underlies a terraced fan. This deposit contains hydrated materials, including Al-phyllosilicates and Fe/Mg-phyllosilicates. Dip measurements indicate that both the eastern and western deposits dip toward the center of the trough, indicating that they postdate formation of the trough and are consequently Late Hesperian or younger in age. Volcanic ash, most likely erupted during formation of the pit crater in the eastern portion of the trough, seems to best explain our observations for several of the units. Valleys sourced from water along the plateau may have flowed into the trough and altered the sediments, with changing aqueous chemistries over time resulting in the diverse range of mineralogies now observed in the eastern light-toned deposit. Our results reveal a complex sedimentary and aqueous history within the Coprates Catena trough, indicating that localized habitable conditions were possible relatively late in Martian history at a time when colder, drier conditions likely dominated the majority of the planet.

  12. Differential insect and mammalian response to Late Quaternary climate change in the Rocky Mountain region of North America

    Elias, Scott A.

    2015-07-01

    Of the 200 beetle species identified from Rocky Mountain Late Pleistocene insect faunal assemblages, 23% are no longer resident in this region. None of the 200 species is extinct. In contrast to this, only 8% of 73 identified mammal species from Rocky Mountain Late Pleistocene assemblages are no longer resident in the Rockies, and 12 species are now extinct. Since both groups of organisms are highly mobile, it would appear that their responses to the large-scale fluctuations of climate associated with the last 125,000 years have been considerably different. Most strikingly contrasting with the insects, there are no mammals in the Rocky Mountain Late Pleistocene fossil record that are found exclusively today in the Pacific Northwest (PNW) region. The PNW does have a distinctive modern mammalian fauna, but only one of these, Keen's Myotis, has a fossil record outside the PNW region, in the eastern and central United States. No modern PNW vertebrate species have been found in any Rocky Mountain fossil assemblages. Based on these data, it appears that there has been little or no mammalian faunal exchange between the PNW region and the Rocky Mountains during the Late Pleistocene or Holocene. This is in stark contrast to the fossil beetle record, where PNW species are a substantial component in many faunas, right through to the Late Holocene.

  13. Late Quaternary cave bears and brown bears in Europe: implications for distribution, chronology, and extinction based on a multidisciplinary approach

    Pacher, Martina

    2010-05-01

    Cave bear remains are one of the most numerous fossils found in European caves. Despite their frequency of occurrence, many aspects of cave bear palaeontology still remain poorly understood. New methodological approaches and ongoing studies led to controversial results and discussion about its taxonomy, palaeoecology, and final extinction. Are we dealing with one single or several species of cave bears? Was cave bear exclusively vegetarian or after all more omnivorous? Did he go extinct before or after the Late Glacial Maximum? Was cave bear restricted to Europe or did he also occur in Asia? Late Pleistocene brown bears, on the other hand, are often rare and little is known about the possible co-occurrence of cave and brown bears during the Late Pleistocene. Based on direct radiocarbon dates the distribution pattern of both, cave and brown bears is reconstructed during the Late Pleistocene in Europe. In addition, the reasons for the achieved pattern will be tested leading to the main question - why did cave bear become extinct while brown bears survived until today? To answer this question palaeobiological data of Late Pleistocene cave and brown bears will be tested against results from isotope analyses, while aDNA data may contribute to the question of distinct local population or even species of bears. The current state of evidence will be presented and on the basis of resulting pattern implications for further multi-disciplinary studies will be discussed.

  14. Late quaternary insects of Rancho La Brea and McKittrick, California

    Miller, Scott E.

    1983-07-01

    Asphalt-impregnated sediments at Rancho La Brea (Los Angeles County) and McKittrick (Kern County) in California provide a rich Quaternary insect record. Ages of various sites at Rancho La Brea range from more than 40,000 14C yr B.P. to modern. McKittrick insects studied by W. D. Pierce are not contemporaneous with the late Pleistocene vertebrate fauna, but are only about 7000 14C yr old. The major paleoecological groupings are: (1) ground dwellers, (2) aquatics. (3) scavengers, and (4) miscellaneous. Contrary to conclusions of earlier authors, most specimens represent modern species. Only two apparent terminal Pleistocene extinctions are recognized. both dung beetles (Scarabaeidae).

  15. Cenozoic stratigraphy of the southern Salar de Antofalla region, northwestern Argentina

    Reno Voss

    2002-12-01

    Full Text Available In the region of the southern Salar de Antofalla (Catamarca Province, northwestern Argentina, Late Eocene to Pliocene/(?Pleistocene successions are exposed with thicknesses of up to 1,600 m. They consist of fluvial, lacustrine and eolian sediments with intercalations of pyroclastic rocks and lava flows. The sedimentary deposits represent 'alluvial fan-playa-complexes' accumulated under a semi-arid to arid climate. From the Late Eocene to the Early Miocene, the sedimentation took place in broken-foreland basins, while from the Early Miocene to the Late Pliocene/(?Early Pleistocene, the sediments mainly accumulated within compressional retroarc basins in which volcanoes partly formed additional basin boundaries. Seven stratigraphic units can be differentiated on the basis of different lithofacies, angular unconformities and different regional distributions: the Late Eocene to Early Miocene Quiñoas Formation, which can be subdivided into the Campo Negro Member, the Cadillo Member and the Aguada Member, the Early/(?Middle Miocene Potrero Grande Formation, the Late Miocene Antofalla Formation, which can be subdivided into the Cajeros Member and Bordo Blanco Member, the Late Miocene Salina beds, the Late Miocene Pozuelos Formation (Orilla Member, the (?Late Miocene/Early Pliocene Sijes Formation (Uncal Grande Member and the Late Pliocene/(?Early Pleistocene Singuel Formation (Agua Escondida Member. While the Quiñoas Formation, the Potrero Grande Formation, the Antofalla Formation and the Salina beds have been newly introduced, the strata which represent the other formations can be assigned to the existing stratigraphic division of the southern Puna. Owing to the fact that these strata had no lateral connection to the strata of their type localities, which crop out near the Salar Pastos Grandes, they were defined as lateral membersEstratigrafía del Cenozoico en la región sur del Salar de Antofalla, noroeste de Argentina. En la parte sur del Salar

  16. Continental margin sedimentation: from sediment transport to sequence stratigraphy

    Nittrouer, Charles A., (Edited By); Austin, James A.; Field, Michael E.; Kravitz, Joseph H.; Syvitski, James P.M.; Wiberg, Patricia L.

    2007-01-01

    This volume on continental margin sedimentation brings together an expert editorial and contributor team to create a state-of-the-art resource. Taking a global perspective, the book spans a range of timescales and content, ranging from how oceans transport particles, to how thick rock sequences are formed on continental margins. - Summarizes and integrates our understanding of sedimentary processes and strata associated with fluvial dispersal systems on continental shelves and slopes - Explores timescales ranging from particle transport at one extreme, to deep burial at the other - Insights are presented for margins in general, and with focus on a tectonically active margin (northern California) and a passive margin (New Jersey), enabling detailed examination of the intricate relationships between a wide suite of sedimentary processes and their preserved stratigraphy - Includes observational studies which document the processes and strata found on particular margins, in addition to numerical models and laboratory experimentation, which provide a quantitative basis for extrapolation in time and space of insights about continental-margin sedimentation - Provides a research resource for scientists studying modern and ancient margins, and an educational text for advanced students in sedimentology and stratigraphy

  17. Stratigraphy of Jurassic coal deposits of Central Tadzhikistan

    Luchnikov, V.S.

    1982-09-01

    Best Jurassic deposits of Central Tadzhikistan are found in the Zeravshand-Gissarski zone at Fan-Yagob coal fields. In spite of exposure, accessibility and abundant plant remains the age of the suites was debatable. Suites were assigned to Upper Triassic, Lower and Middle Jurassic periods at the Stratigraphic Conference at Samarkand, 1971. In recent years, prospecting for coal has led to the need for development of detailed stratigraphy of the continental Jurassic of this region including age of previously delineated suites. Investigators conducted litho-stratigraphic studies. Plant remains from 39 flora containing horizons, though not distributed uniformly, revealed development of plant societies in Early and Middle Jurassic and confirmed or corrected assignment of different suites. A table presents species of plant remains found in the strata. A description of suites and their fossilized contents follows. As a result of these investigations, the stratigraphy of the Jurassic strata is refined, age of suites determined and list of flora extended. The Jurassic flora of Fan-Yagob in composition and characteristics of development is a typical flora of the Central Asiatic Province of the Indo-European paleofloral region. (In Russian)

  18. Characteristics of Late Quaternary Activity of the Luhuatai Buried Fault Revealed by Drilling

    Lei Qiyun; Chai Chizhang; Du Peng; Wang Yin; Meng Guangkui

    2012-01-01

    The Luhuatai fault is one of the important buried tectonics in the Yinchuan basin. Based on the results of shallow seismic exploration, we conducted composite drilling section exploration and dating of the samples from boreholes. Some useful data was obtained, such as the depth of the upper breaking point, the latest activity age, displacement in the late Quaternary, and slip rates, etc. This study shows that the activity is different between the north and south segment along the Luhuatai fault. The north segment is a Holocene fault, while the south segment is a late mid-Pleistocene fault. From north to south along the north segment of Luhuatai fault, the activity has been enhanced, and the faulting is stronger in late Pleistocene than Holocene.

  19. {13C }/{12C } ratios of pleistocene mummified remains from beringia

    Bombin, Miguel; Muehlenbachs, Karlis

    1985-01-01

    During the Quaternary glacial episodes, when sea level was considerably lower, Asia and North America were linked by large extensions of circumarctic land (Beringia), which remained unglaciated. This land mass served not only as a biogeographical bridge for plants, animals, and humans, but also supported a biome very different from present tundra or boreal coniferous forests, which was dominated by steppes and a rich mammalian megafauna. Carbon stable isotope ratios of Beringian late Pleistocene mummified remains of bison, equids, mammoth, caribou, musk-ox, moose, woolly rhino, and other undetermined species, found preserved in permafrost, indicate that these megaherbivores fed exclusively on C 3 plants, and that C 4 grasses were not differentially ingested by bison, as previously suggested. Paleoclimatic constraints probably prevented the formation of a warm-season (C 4) guild during the later part of the growing season in the steppes of Beringia during the last glaciation.

  20. The Pleistocene evolution of the East Antarctic Ice Sheet in the Prydz bay region: Stable isotopic evidence from ODP Site 1167

    Theissen, K.M.; Dunbar, R.B.; Cooper, A. K.; Mucciarone, D.A.; Hoffmann, D.

    2003-01-01

    Ocean Drilling Program Leg 188, Prydz Bay, East Antarctica is part of a larger initiative to explore the Cenozoic history of the Antarctic Ice Sheet through direct drilling and sampling of the continental margins. In this paper, we present stable isotopic results from Ocean Drilling Program (ODP) Site 1167 located on the Prydz Channel Trough Mouth Fan (TMF), the first Antarctic TMF to be drilled. The foraminifer-based ??18O record is interpreted along with sedimentary and downhole logging evidence to reconstruct the Quaternary glacial history of Prydz Bay and the adjacent Lambert Glacier Amery Ice Shelf System (LGAISS). We report an electron spin resonance age date of 36. 9 ?? 3.3 ka at 0.45 m below sea floor and correlate suspected glacial-interglacial cycles with the global isotopic stratigraphy to improve the chronology for Site 1167. The ??18O record based on planktonic (Neogloboquadrina pachyderma (s.)) and limited benthic results (Globocassidulina crassa), indicates a trend of ice sheet expansion that was interrupted by a period of reduced ice volume and possibly warmer conditions during the early-mid-Pleistocene (0.9-1.38 Ma). An increase in ?? 18O values after ??? 900 ka appears to coincide with the mid-Pleistocene climate transition and the expansion of the northern hemisphere ice sheet. The ??18O record in the upper 50 m of the stratigraphic section indicates as few as three glacial-interglacial cycles, tentatively assigned as marine isotopic stages (MIS) 16-21, are preserved since the Brunhes/Matuyama paleomagnetic reversal (780 ka). This suggests that there is a large unconformity near the top of the section and/or that there may have been few extreme advances of the ice sheet since the mid-Pleistocene climate transition resulting in lowered sedimentation rates on the Prydz Channel TMF. The stable isotopic record from Site 1167 is one of the few available from the area south of the Antarctic Polar Front that has been linked with the global isotopic

  1. Pleistocene niche stability and lineage diversification in the subtropical spider Araneus omnicolor (Araneidae.

    Elen A Peres

    Full Text Available The influence of Quaternary climate oscillations on the diversification of the South American fauna is being increasingly explored. However, most of these studies have focused on taxa that are endemic to tropical environments, and relatively few have treated organisms restricted to subtropical biomes. Here we used an integrative phylogeographical framework to investigate the effects of these climate events on the ecological niche and genetic patterns of the subtropical orb-weaver spider Araneus omnicolor (Araneidae. We analyzed the mitochondrial (Cytochrome Oxidase I, COI and nuclear (Internal Transcribed Subunit II, ITS2 DNA of 130 individuals throughout the species' range, and generated distribution models in three different climate scenarios [present, Last Glacial Maximum (LGM, and Last Interglacial Maximum (LIG]. Additionally, we used an Approximate Bayesian Computation (ABC approach to compare possible demographic scenarios and select the hypothesis that better explains the genetic patterns of A. omnicolor. We obtained high haplotype diversity but low nucleotide variation among sequences. The population structure and demographic analyses showed discrepancies between markers, suggesting male-biased dispersal in the species. The time-calibrated COI phylogenetic inference showed a recent diversification of lineages (Middle/Late Pleistocene, while the paleoclimate modeling indicated niche stability since ~120 Kya. The ABC results agreed with the niche models, supporting a panmictic population as the most likely historical scenario for the species. These results indicate that A. omnicolor experienced no niche or population reductions during the Late Pleistocene, despite the intense landscape modifications that occurred in the subtropical region, and that other factors beside LGM and LIG climate oscillations might have contributed to the demographic history of this species. This pattern may be related to the high dispersal ability and wide

  2. Pleistocene niche stability and lineage diversification in the subtropical spider Araneus omnicolor (Araneidae).

    Peres, Elen A; Sobral-Souza, Thadeu; Perez, Manolo F; Bonatelli, Isabel A S; Silva, Daniel P; Silva, Márcio J; Solferini, Vera N

    2015-01-01

    The influence of Quaternary climate oscillations on the diversification of the South American fauna is being increasingly explored. However, most of these studies have focused on taxa that are endemic to tropical environments, and relatively few have treated organisms restricted to subtropical biomes. Here we used an integrative phylogeographical framework to investigate the effects of these climate events on the ecological niche and genetic patterns of the subtropical orb-weaver spider Araneus omnicolor (Araneidae). We analyzed the mitochondrial (Cytochrome Oxidase I, COI) and nuclear (Internal Transcribed Subunit II, ITS2) DNA of 130 individuals throughout the species' range, and generated distribution models in three different climate scenarios [present, Last Glacial Maximum (LGM), and Last Interglacial Maximum (LIG)]. Additionally, we used an Approximate Bayesian Computation (ABC) approach to compare possible demographic scenarios and select the hypothesis that better explains the genetic patterns of A. omnicolor. We obtained high haplotype diversity but low nucleotide variation among sequences. The population structure and demographic analyses showed discrepancies between markers, suggesting male-biased dispersal in the species. The time-calibrated COI phylogenetic inference showed a recent diversification of lineages (Middle/Late Pleistocene), while the paleoclimate modeling indicated niche stability since ~120 Kya. The ABC results agreed with the niche models, supporting a panmictic population as the most likely historical scenario for the species. These results indicate that A. omnicolor experienced no niche or population reductions during the Late Pleistocene, despite the intense landscape modifications that occurred in the subtropical region, and that other factors beside LGM and LIG climate oscillations might have contributed to the demographic history of this species. This pattern may be related to the high dispersal ability and wide environmental

  3. Climatic variability and plant food distribution in Pleistocene Europe: Implications for Neanderthal diet and subsistence

    Hardy, Bruce L.

    2010-03-01

    Contrary to their cold-adapted image, Neanderthals inhabited Pleistocene Europe during a time of great climatic fluctuation with temperatures ranging from as warm as present-day during the last interglacial to as cold as those of the last glacial maximum. Cold-adapted Neanderthals are similarly most often associated with the exploitation of large mammals who are themselves cold-adapted (mammoth, bison, reindeer, etc.). Cold, high-latitude environments are typically seen as lacking in plants generally and in plant foods in particular. Plant foods are therefore usually ignored and Neanderthals are increasingly being viewed as top carnivores who derived the vast majority of their diet from meat. Support for this hypothesis comes largely from stable isotope analysis which tracks only the protein portion of the diet. Diets high in lean meat largely fulfill micronutrient needs but can pose a problem at the macronutrient level. Lean meat can compose no more than 35% of dietary energy before a protein ceiling is reached. Exceeding the protein ceiling can have detrimental physiological effects on the individual. Neanderthals would have needed energy from alternative sources, particularly when animals are fat-depleted and lean meat intake is high. Underground storage organs (USOs) of plants offer one such source, concentrating carbohydrates and energy. USOs could also provide an important seasonal energy source since they are at their maximum energy storage in late fall/winter. Although Paleolithic sites are increasingly yielding plant remains, their presence is rare and they are often given only passing mention in Neanderthal dietary reconstructions. The complexity and number of potential wild plant foods, however, defies easy discussion. Native European wild edible plants with starchy USOs would have been potentially available throughout the Neanderthal range, even during the coldest periods of the Late Pleistocene.

  4. Middle Pleistocene volcanic activity dated by red thermoluminescence (RTL) - a case study from Lanzarote (Canary Islands)

    von Suchodoletz, H.; Blanchard, H.; Rittner, S.; Radtke, U.; Fuchs, M.; Dietze, M.; Zöller, L.

    2009-04-01

    On Lanzarote (Canary Islands) soils were baked by Quaternary lava flows. This offers the possibility to date phases of eruptive activity by red thermoluminescence (RTL). We dated soil material baked by two different lava flows originating from the "Las Calderetas de Guatiza" volcanic chain in the northeast of the island by RTL. Furthermore, three samples of Helicidae-mollusk shells overlying one of the lava flows (site Mála) were dated using electron spin resonance (ESR). RTL datings were carried out using quartz grains 63-200 µm from baked material that were originally brought by eolian transport from the nearby Saharan desert. It appears that in spite of a baking temperature dating by RTL was possible. RTL ages of ca. 170 ka show good agreement with each other, however, ESR ages are up to 40 % higher than the corresponding RTL age of the lava flow in Mála. Despite this disagreement these results demonstrate that eruptive activity of the volcanic chain occurred during the Middle Pleistocene rather than during the Early Holocene/Late Pleistocene as supposed based on geomorphologic features. Furthermore, they show that 14C-ages of mollusk shells originating from Mála are underestimating volcanic activity up to a factor of 10, a problem often recorded in arid areas. These results demonstrate the value of luminescence and ESR datings on the semi arid Eastern Canary Islands. The successful dating of lava-baked soils on Lanzarote by RTL thus offers the possibility to further investigate the yet fragmentary Middle and Late Quaternary eruptive history of these islands.

  5. Multilocus Phylogeography of the Treefrog Scinax eurydice (Anura, Hylidae) Reveals a Plio-Pleistocene Diversification in the Atlantic Forest

    Menezes, Lucas; Canedo, Clarissa; Batalha-Filho, Henrique; Garda, Adrian Antonio; Gehara, Marcelo; Napoli, Marcelo Felgueiras

    2016-01-01

    We aim to evaluate the genetic structure of an Atlantic Forest amphibian species, Scinax eurydice, testing the congruence among patterns identified and proposed by the literature for Pleistocene refugia, microrefugia, and geographic barriers to gene flow such as major rivers. Furthermore, we aim to evaluate predictions of such barriers and refugia on the genetic structure of the species, such as presence/absence of dispersal, timing since separation, and population expansions/contractions. We sequenced mitochondrial and nuclear genetic markers on 94 tissue samples from 41 localities. We inferred a gene tree and estimated genetic distances using mtDNA sequences. We then ran population clustering and assignment methods, AMOVA, and estimated migration rates among populations identified through mtDNA and nDNA analyses. We used a dated species tree, skyline plots, and summary statistics to evaluate concordance between population’s distributions and geographic barriers and Pleistocene refugia. Scinax eurydice showed high mtDNA divergences and four clearly distinct mtDNA lineages. Species tree and population assignment tests supported the existence of two major clades corresponding to northeastern and southeastern Atlantic Forest in Brazil, each one composed of two other clades. Lineage splitting events occurred from late Pliocene to Pleistocene. We identified demographic expansions in two clades, and inexistent to low levels of migrations among different populations. Genetic patterns and demographic data support the existence of two northern Refuge and corroborate microrefugia south of the Doce/Jequitinhonha Rivers biogeographic divide. The results agree with a scenario of recent demographic expansion of lowland taxa. Scinax eurydice comprises a species complex, harboring undescribed taxa consistent with Pleistocene refugia. Two rivers lie at the boundaries among populations and endorse their role as secondary barriers to gene flow. PMID:27248688

  6. Soil-landscape development and late Quaternary environmental change in coastal Estremadura, Portugal

    Daniels, Michael; Haws, Jonathan; Benedetti, Michael; Bicho, Nuno

    2015-04-01

    This poster integrates soil-landscape analysis with archaeological survey and paleoenvironmental reconstruction. Soils in surface and buried contexts in Estremadura, Portugal, provide evidence of landscape stability and instability, relative age relationships between landforms, and general paleoenvironmental conditions during the late Quaternary. These factors provide insight into the distribution and condition of Paleolithic archaeological sites and help understand the record of human settlement in the region. Late Pleistocene and Holocene dunes extend inland approximately 10 km from coastal source regions. Surface soils in Holocene dunes under maritime pine (Pinus pinaster) forest exhibit A, E, C/Bh and A, C horizon sequences and classify as Quartzipsamments. Surface soils in late Pleistocene dunes exhibit A, E, Bh, Bhs, Bs horizon sequences and classify as Haplorthods. Both Pleistocene and Holocene dunes commonly bury a heavily weathered soil formed in calcareous sandstone. The boundary between underlying buried soils and overlying surface soils is characterized by a lag deposit of medium to coarse, moderately-rounded gravels, underlain immediately by subsurface Bt and Bss horizons. The lag deposit and absence of buried A horizons both indicate intense and/or prolonged surface erosion prior to burial by late Quaternary dunes. Soil-geomorphic relationships therefore suggest at least two distinct episodes of dune emplacement and subsequent landscape stability following an extensive episode late Pleistocene landscape instability and soil erosion. A conceptual model of soil-landscape evolution through the late Quaternary and Holocene results from the integration of soil profile data, proxy paleoenvironmental data, and the partial record of human settled as revealed in the archaeological record.

  7. LATE CREATACEOUS-CENOZOIC SEDIMENTS OF THE BAIKAL RIFT BASIN AND CHANGING NATURAL CONDITIONS

    Viktor D. Mats

    2015-09-01

    Full Text Available The late Cretaceous-Cenozoic sediments of fossil soils and weathering crusts of the Baikal rift have been subject to long-term studies. Based on our research results, it is possible to distinguish the following litho-stratigraphic complexes which are related to particular stages of the rift development: the late Cretaceous–early Oligocene (crypto-rift Arheo-baikalian, the late Oligocene–early Pliocene (ecto-rift early orogenic Pra-baikalian, and the late Pliocene-Quaternary (ecto-rift late orogenic Pra-baikalian – Baikalian complexes. Changes of weathering modes (Cretaceous-quarter, soil formation (Miocene-quarter and differences of precipitation by vertical and lateral stratigraphy are analysed with regard to specific features of climate, tectonics and facial conditions of sedimentation. Tectonic phases are defined in the Cenozoic period of the Pribaikalie.

  8. Stable isotope records of inland California megafauna - new insights into Pleistocene paleoecology and paleoenvironmental conditions

    Trayler, R. B.; Dundas, R. G.; Van De Water, P. K.; Fox-Dobbs, K.

    2012-12-01

    Paleodietary studies of California megafauna have focused primarily on the coastal late Pleistocene Rancho La Brea tar seeps (RLB) in Los Angeles, while other sites remain understudied. We examined two Pleistocene fossil localities from inland California (San Joaquin Valley) and report δ13C and δ18O values measured from tooth enamel of mammalian megafauna at both sites. The late Pleistocene McKittrick tar seeps in Kern County has a similar fauna to RLB. The middle Irvingtonian (~700,000 year old) Fairmead Landfill site, near Chowchilla, contains a megafaunal assemblage dominated by Equus, Camelops and Mammuthus. We used stable isotope values measured in carnivore and herbivore tooth enamel to investigate paleodietary and paleoecological patterns at both sites. δ13C values of tooth enamel is controlled by diet and can be used to investigate resource usage and partitioning among and between taxa. In large mammals δ18O ratios are controlled by drinking water, and by proxy, climate. Ontogenetic serial tooth δ18O and δ13C reveal seasonal trends in resource usage, from which we can infer patterns of forage availability. We sampled 85 individuals from 16 taxa; Arctodus, Bison, Camelops, Canis, Capromeryx, Cervus, Equus, Hemiauchenia, Homotherium, Mammut, Mammuthus, Miracinonyx, Panthera, Platygonus, Smilodon and Tetrameryx. Faunal δ13C differ significantly (pdiets trending towards forested habitats, while canids exhibit generalist diets. We serially sampled multiple teeth from both sites to investigate seasonality and temporal resource usage among megafauna. Equus from both localities showed little variation in δ13C, while at McKittrick Camelops diet included variable amounts of C4 resources throughout a seasonal cycle. We also report the first ever serial sampled Tetrameryx tooth; δ13C variation throughout the tooth is low suggesting a stable diet. Comparing similarly aged inland McKittrick and coastal RLB faunas reveal significant differences (p<0.001). Bison

  9. Middle Pleistocene palaeoenvironmental changes of the eastern Canary Islands - revealed by the Mála dune-palaeosol-sequence at Lanzarote (Canary Islands)

    von Suchodoletz, H.; Zöller, L.; Hilgers, A.; Radtke, U.; Faust, D.

    2012-04-01

    The Canary Islands are located at the transition between the Mediterranean and the Saharan climate off NW-Africa. Thus, they are a key area for the investigation of palaeoenvironmental changes. Several terrestrial studies investigated the palaeoenvironmental development of that region during the later part of the last glacial cycle. However, apart from recent investigations of "vega" sediments on Lanzarote Island (Suchodoletz et al. 2010) the palaeoenvironmental evolution during the Middle Pleistocene is hardly studied yet, basically due to the lack of reliable geochronological data. The Mála dune-palaeosol-sequence is located in the north of Lanzarote. It consists of marine shell detritus originally blown out from the insular shelf during periods of low global sea level, and to a small part of Saharan dust and fine quartz sand. The aeolian layers are intercalated with up to eight silty-clayey palaeosol horizons. Unlike the dune sands, the soils indicate stable landscape conditions with trapping of Saharan dust. Using a combination of ESR and luminescence dating techniques, we are able to place this sequence into the Middle Pleistocene, in contrast to former investigations based on 14C datings postulating a Late Pleistocene age (Ortiz et al. 2006). As a consequence, clayey-silty palaeosols represent periods of stable landscape conditions in the Canarian region during the Middle Pleistocene, which we compare with marine palaeoclimatic studies from the area.

  10. Mitochondrial phylogeny shows multiple independent ecological transitions and northern dispersion despite of Pleistocene glaciations in meadow and steppe vipers (Vipera ursinii and Vipera renardi).

    Zinenko, Oleksandr; Stümpel, Nikolaus; Mazanaeva, Lyudmila; Bakiev, Andrey; Shiryaev, Konstantin; Pavlov, Aleksey; Kotenko, Tatiana; Kukushkin, Oleg; Chikin, Yury; Duisebayeva, Tatiana; Nilson, Göran; Orlov, Nikolai L; Tuniyev, Sako; Ananjeva, Natalia B; Murphy, Robert W; Joger, Ulrich

    2015-03-01

    The phylogeny and historical demography of small Eurasian vipers of the Vipera ursinii and V. renardi complexes were studied using mitochondrial DNA sequences analysed with Bayesian inference, Maximum Likelihood and Maximum Parsimony approaches, and mismatch distributions. Diversification in the group resulted from an initial dispersion in the later Pliocene - Pleistocene in two directions: north-westwards via the Balkans (V. ursinii complex) and north-eastwards from Asia Minor via the Caucasus (V. renardi complex). An independent, comparatively recent transition occurred from montane habitats to lowland grasslands in different mitochondrial lineages during the Late Pleistocene, when representatives of the both complexes had reached lowland steppes to the north. Effective population size showed clear signs of rapid growth in eastern V. renardi, triggered by colonization of vast lowland steppes, but in western V. ursinii complex grew during the Last Glaciation and experienced stabilization in Holocene. Expansion and population growth in lowland lineages of V. renardi was not strongly affected by Pleistocene climatic oscillations, when cold, dry conditions could have favoured species living in open grasslands. The high diversity of closely related haplotypes in the Caucasus and Tien-Shan could have resulted from repetitive expansion-constriction-isolation events in montane regions during Pleistocene climate fluctuations. The mitochondrial phylogeny pattern conflicts with the current taxonomy. PMID:25527984

  11. Upper Pleistocene and Holocene palaeoenvironmental records in Cueva Mayor karst (Atapuerca, Spain from different proxies: speleothem crystal fabrics, palynology and archaeology.

    Virginia Martínez-Pillado

    2014-01-01

    Full Text Available The Cueva Mayor karst system of Atapuerca, in Northern Spain, hosts a highly significant record of human occupation from the Pleistocene. The climatic context of the human activities during the Pleistocene-Holocene for this inland site has not been well constrained, since existing records of the palaeoclimatic evolution of the Northern Iberian Peninsula are from more distal coastal and high-elevation sites. In this study, we interpret the palaeoenvironmental information recorded on the petrography of a stalagmite and the pollen spectra of the Sierra de Atapuerca karst system during the last 20 kyr. The integration of both types of records has allowed us to define four palaeoenvironmental stages. During the Upper Pleistocene and until 12.8 kyr BP, the climate was cold and dry, toward the end of the interval evolving to wetter and warmer conditions. From 12.8 to 7.7 kyr BP, during the Mesolithic-Neolithic, a major erosion event in both records marks the Pleistocene-Holocene transition. Around 5.9 kyr BP, the Late Neolithic, environmental conditions indicate a climatic optimum with a marked seasonality. The environmental conditions became drier from 4.2 kyr BP until the present, with a decrease in the woodlands. This aridity signal might be amplified by the impact of a more intense human agricultural activity after 3.1 kyr BP, during the Bronze Age.

  12. Early hominin speciation at the Plio/Pleistocene transition.

    Cameron, D W

    2003-01-01

    Over the last half-decade or so, there has been an explosion in the recognition of hominin genera and species. We now have the late Miocene genera Orrorin and Sahelanthropus, the mid Pliocene genus Kenyanthropus, three new Pliocene species of Australopithecus (A. anamensis, A. garhi and A. bahrelghazali) and a sub species of Ardipithecus (Ar. r. kadabba) to contend with. Excepting also the more traditional species allocated to Paranthropus, Australopithecus and early Homo we are approaching around 15 species over 5 million years (excluding hominin evolution over the last one million years). Can such a large number of hominin species be justified? An examination of extant hominid (Gorilla gorilla, Pan troglodytes, and Pan paniscus) anatomical variability indicates that the range of fossil hominin variability supports the recognition of this large number of fossil species. It is also shown that not all hominins are directly related to the emergence of early Homo and as such have become extinct. Indeed the traditional australopithecine species 'A'. anamensis, 'A'. afarensis and 'A'. garhi are considered here to belong to a distinct genus Praeanthropus. They are also argued not be hominins, but rather an as yet undefined hominid group from which the more derived hominins evolved. The first hominin is represented by A. africanus or a hominin very much like it. The Paranthropus clade is defined by a derived heterochronic condition of peramorphosis, associated with sequential progenesis (contraction of successive growth stages) in brain and dental development, but a mixture of peramorphic and paedomorphic features in its craniofacial anatomy. Conversely, Kenyanthropus and Homo both share a pattern of peramorphosis, associated with sequential hypermorphosis (prolongation of successive growth stages) in brain development, and paedomorphosis processes in cranial, facial and dental development. This suggests, that these two clades share an important synapomorphy not

  13. A late Pleistocene paleohydrologic record of Sierra Nevada runoff from Owens Lake, California [abstract

    Bradbury, J. Platt

    1996-01-01

    EXTRACT (SEE PDF FOR FULL ABSTRACT): A 323-meter (about 800,000 year) core of lake deposits beneath Owens Lake playa, Inyo County, California, contains a nearly continuous paleolimnological record based on diatom assemblages. ... Throughout most of its history, Owens Lake was characterized by freshwater diatoms, indicating a positive hydrologic input from the Owens River and overflow to lake systems downstream.

  14. Late Pleistocene-Holocene morphosedimentary architecture, Spiti River, arid higher Himalaya

    Srivastava, Pradeep; Ray, Yogesh; Phartiyal, Binita; Sharma, Anupam

    2013-03-01

    The Spiti River drains the rain shadow zone of western Himalaya. In the present study, the fluvial sedimentary record of Spiti valley was studied to understand its responses to tectonics and climate. Geomorphic changes along the river enable to divide the river into two segments: (i) upper valley with a broad, braided channel where relict sedimentary sequences rise 15-50 m high from the riverbed and (ii) lower valley with a narrow, meandering channel that incises into bedrock, and here, the fluvio-lacustrine sediments reside on a bedrock bench located above the riverbed. The transition between these geomorphic segments lies along the river between Seko-Nasung and Lingti villages (within Tethyan Himalaya). Lithofacies analyses of the sedimentary sequences show six different lithofacies. These can be grouped into three facies associations, viz. (A) a glacial outwash; (B) sedimentation in a channel and in an accreting bar under braided conditions; and (C) formation of lake due to channel blockage by landslide activities. Seventeen optically stimulated luminescence ages derived from ten sections bracketed the phases of river valley aggradation between 14-8 and 50-30 ka. These aggradation phases witnessed mass wasting, channel damming and lake formation events. Our record, when compared with SW monsoon archives, suggests that the aggradation occurred during intensified monsoon phase of MIS 3/4 and that proceeded the Last Glacial Maxima. Thus, the study reports monsoon modulated valley aggradation in the NW arid Himalaya.

  15. The Late-Pleistocene sedimentation history in the Eastern Arabian Sea: Climate Weathering-Productivity linkage

    Chodankar, A.R.

    solution was analysed for Calcium (Ca) in a Perkin-Elmer? OPTIMA-2000 DV ICP-OES. The measured Ca was translated in to CaCO3 using a conversion factor of 2.497. The accuracy of the measurement was assessed by analysing AR-grade synthetic CaCO3 powder... isotopes and precipitated water is richer in H216O than the seawater from which it was evaporated. On a global scale, when 16O-enriched water vapour is precipitated as snow and builds up to form glaciers and ice-caps, then the oceans will have lost...

  16. Dolomitization in a mixing zone of near-seawater composition, Late Pleistocene, northeastern Yucatan Peninsula

    Ward, W. C.; Halley, Robert B.

    1985-01-01

    Patches of dolomite occur in cores of reefal limestone from the shallow subsurface on the northeastern coast of the Yucatan Peninsula. This limestone accumulated during an interglacial high stand of sea level about 200,000 years ago. Dolomitization was preceded by freshwater diagenesis, including precipitation of sparry calcite cement, stabilization of Mg-calcitic skeletal fragments, and partial dissolution of aragonitic components. This suggests a predolomitization lowering of sea level with the consequent freshening of pore water. The subsequent precipitation of dolomite indicates a return to high sea level with the consequent increase in Mg/Ca ratio of pore water. Dolomitization took place during a brief high stand of sea level, either shortly after deposition about 200,000 yr BP, r, more likely, about 125,000 yr BP.

  17. Barbados Oxygen Isotope Data (delta 18O) for the Late Pleistocene

    National Oceanic and Atmospheric Administration, Department of Commerce — Coral-based delta18O time-series derived from measurements made on submerged or drowned coral reef sequence. The core samples used have been described elsewhere...

  18. Water masses of the northern part of the Iceland Basin in the late Pleistocene

    Lukashina, N. P.

    2013-02-01

    A core of bottom sediments AMK-4438 with a length of 320 cm was taken in the North-Eastern part of the Iceland Basin from the depth of 2240 m. The continuous sampling (every 2 cm) made it possible to study the core using the principle of high-resolving paleoceanology. For the stratigraphic partition of the core, we applied the paleotemperature analysis by planktonic foraminifera and carbonate analysis; the distribution of the iceberg rafted debris (IRD) was studied. As a result, nine isotopic stages were distinguished. The change in the complexes of benthic foraminifera indicates that the present-day deepwater circulation in the North-Eastern part of the Iceland Basin had no analogs in earlier glacial periods, including the MIS 5 age. During almost 300 ka, there were relatively warm, rich in nutrients, and poor in oxygen water masses. The formation of the modern Northern-Eastern deep water in the Iceland Basin began in the Bolling-Allerod 14 ka B.P.

  19. Buried late Pleistocene fluvial channels on the inner continental shelf off Vengurla, west coast of India

    SubbaRaju, L.V.; Krishna, K.S.; Chaubey, A.K.

    with sediments. Cross sectional dimensions between 15 to 100 m width and 2 to 6 m depth suggest a fluvial origin of the channels. These buried channels appear to mark former positions of rivers flowing from the nearby coast and debouching into the Arabian Sea...

  20. Late Pleistocene wind-action and periglacial phenomena in sandy terrain, New Jersey Pine Barrens

    Demitroff, M. N.; Cicali, M.

    2013-12-01

    Examination of the Pinelands past permafrost environment will add insight to the relatively scant record of the Mid-Atlantic region's periglacial realm, a place where cold, dry, and windy conditions predominated during the recent glacials. This area is especially important to the understanding of mid-latitudinal climate change dynamics in ice-marginal locations - areas greatly affected by diurnal, seasonal, and long-term climate perturbations. We provide examples from a well-preserved pine-forest reserve on coastal plain (39-40° N) that experienced multiple episodes of permafrost aggradation and degradation during the last 200,000 years. While a large number of publications describe an array of relict periglacial phenomena from low-relief areas in Europe's sand belt (UK-Russia), much less is known about the ice-marginal continental mass of North America. High-resolution geodetically corrected airborne LiDAR data enhanced with alternate views through the use of early aerial photo imagery is provided and analyzed to produce bare earth landforms revealing perspective eolian structures. Fieldwork at sand mine operations adjacent to relict dune fields offered sectional views of what lies beneath wind-affected land surfaces. This region was found to have been sparsely vegetated land akin to polar barrens during cold epochs. Coversand is the dominant eolian depositional form, with parabolic dune fields scattered along downwind banks of larger watercourses. Eolian systems interact with the local paleohydrology. Wind-erosional features include ventifacts, blowouts, and, on occasion, yardangs. Sand-filled frost cracks attest to aridity during permafrost aggradation and deep-seasonal frost. These periglacial macrostructures often deform into furrows and sediment-filled pots upon permafrost degradation. The sites are easily accessible providing ample opportunities for frozen ground and climate change studies.