Two new records of glacial stratigraphy obtained from borecores collected in southcentral Saskatchewan are compared to previously published records from Wellsch Valley and Swift Current Creek in southern Saskatchewan. The comparisons are based on magnetostratigraphy and tephrochronology, and describe preglacial, glacial, and interglacial deposits. The new stratigraphy is compared to the composite global marine oxygen isotope record. Although the ages and extents of late Pleistocene continental glaciations are relatively well constrained, they are less well defined for the middle and early Pleistocene. Data presented here highlight recent studies carried out from borecores and outcrops of extensive pre-Illinoian (pre-Saalian) glacial deposits. Based on this new data, at least seven Laurenti...

A Plio-Pleistocene alluvial fan near La Regia, in the southeast coast of Spain contains a vertical series of 7 fossil soils and 7 calcrete complexes. The soil stratigraphy reflects recurring alternation of sedimentation and soil formation suggesting numerous, pedogenically effective cyclical climatic changes during the Late Pliocene and Early Pleistocene. The differentiated composition of calcretes near La Regia is a polygenetic product: Surface erosion and sedimentary fossilization were followed by secondary carbonatization and subsequent induration. At least 15 stages of soil formation are reconstructed. Red paleosols and pedogenic calcretes are well developed and reflect humid subtropical and Mediterranean conditions during soil genesis with geomorphodynamic stability. In contrast, the ...

South of Flathead Lake, fault scarps on late Quaternary surfaces are nearly continuous for 45 km along the western flank of the Mission Range. On late Pleistocene alpine lateral moraines, scarp heights reach a maximum of 17 m. Scarp heights on post glacial Lake Missoula surfaces range from 2.6--7.2 m and maximum scarp angles range from 10[degree]--24[degree]. The stratigraphy exposed in seven trenches across the fault demonstrates that the post glacial Lake Missoula scarps resulted from at least two surface-faulting events. Larger scarp heights on late Pleistocene moraines suggests a possible third event. This yields an estimated recurrence of 4--8 kyr. Analyses of scarp profiles show that the age of the most surface faulting is middle Holocene, consistent with stratigraphic evidence found in the trenches. Rupture length and displacement imply earthquake magnitudes of 7 to 7.5. Previous studies have not identified geologic evidence of late Quaternary surface faulting in the Rocky Mountain Trench or on faults north of the Lewis and Clark line despite abundant historic seismicity in the Flathead Lake area. In addition to the Mission fault, reconnaissance studies have located late Quaternary fault scarps along portions of faults bordering Jocko and Thompson Valleys. These are the first documented late Pleistocene/Holocene faults north of the Lewis and Clark line in Montana and should greatly revise estimates of earthquake hazards in this region.

Sediments of the Wilson Creek Formation surrounding Mono Lake preserve a high-resolution archive of glacial and pluvial responses along the eastern Sierra Nevada due to late Pleistocene climate change. An absolute chronology for the Wilson Creek stratigraphy is critical for correlating the paleoclimate record to other archives in the western U.S. and the North Atlantic region. However, multiple attempts to date the Wilson Creek stratigraphy using carbonates and tephras yield discordant results due to open-system effects and radiocarbon reservoir uncertainties as well as abundant xenocrysts. New ion microprobe 238U-230Th dating of the final increments of crystallization recorded by allanite and zircon autocrysts from juvenile pyroclasts yield ages that effectively date eruption of key tephr...

This study utilizes a multidisciplinary approach to the investigation of the extent, timing, and potential effects of repeated Pleistocene glaciation in Bering Strait region. A major focus of this study was directed toward testing the hypothesis that a continental-scale ice sheet existed in Beringia during the Late Wisconsin glacial period. Satellite synthetic aperture radar (SAR) imagery was used to compile a map of glacial moraines in Chukotka, Russia, and to attempt preliminary correlations with the glacial record in Alaska. Geophysical modelling of the solid-earth response to postulated glacial loading, and the reconstruction of regional snowline were combined with the results of the SAR investigation to test the ice sheet hypothesis. Finally, a detailed study of the Quaternary stratigraphy and surficial geology of St. Lawrence Island was used to correlate the glacial and sea level histories of western Alaska and Chukotka, Russia. The sequences of moraines in Chukotka, mapped from SAR imagery, are similar in morphology and position to moraine sequences described in Alaska, recording a succession of glacial events that most likely began in the middle Pleistocene and ended with the Late Wisconsin. The record of repeated mountain glaciation, characterized by radial flow out of high topographic areas provides strong evidence against the existence of a southward-flowing, continental-scale ice sheet in Beringia at any time in the latter part of the Pleistocene. Geophysical modelling of the solid-earth response to glacial loading predicted relative sea level changes on the scale of meters to tens of meters (rising or falling depending on forebulge effect) around the shores of present-day Bering Strait if a large ice sheet had, indeed, occupied the Beringia during Late Wisconsin time. There is no evidence of these predicted sea level changes anywhere in the region. The reconstruction of Late Wisconsin snowlines in Russian and Alaska show that the paleoclimatic conditions needed to 'grow' the hypothesized ice sheet did not exist. Field mapping and stratigraphic work on St. Lawrence Island revealed that ice advanced onto the island twice in the late Pleistocene, once in the Middle Pleistocene and once after the Last Interglacial, probably during the Early Wisconsin. The record of glaciers advancing from Chukotka onto the island provides an important 'Rosetta Stone' for correlating the glacial histories of northeast Siberia and Alaska.

The Holocene and late Pleistocene environmental history of the teri ('sandy waste' in local parlance) red sands in the southeast coastal Tamil Nadu was examined using remote sensing, stratigraphy, and optically stimulated luminescence (OSL) dating. Geomorphological surveys enabled the classification of the teri red sands as, 1) inland fluvial teri, 2) coastal teri and, 3) near-coastal teri dunes. The inland teri sediments have higher clay and silty-sand component than the coastal and near-coastal teri, suggesting that these sediments were deposited by the fluvial process during a stronger winter monsoon around >15ka. The coastal teri dunes were deposited prior to 11.4+/-0.9ka, and the near-coastal dunes aggraded at around 5.6+/-0.4ka. We interpret that the coastal dunes were formed during ...

We use a combined allostratigraphic and morpholithostratigraphic approach to establish a relative stratigraphy of macroscale sediment-landform units in the Mediterranean Palancia River watershed (986-km^2, NE Spain). Four alloformations signifying important changes in (sub)regional scale geomorphic valley-floor evolution were identified based on data from 1120 field sites and age determinations, and from analyzing high resolution geodata. The formation of the widespread and thick Pleistocene alloformation can be attributed to climatically-induced excessive sediment supply and flood activities during Pleistocene cold intervals - rather than representing time-lagging response to Plio/Pleistocene neotectonic uplift. Triggered by the turn to Holocene climatic conditions, three successively ins...

Northeast India is one of the poorly documented areas archaeologically and hardly is considered in the discussions on Indian prehistory. To date, no site has pushed back the antiquity of human presence in this region prior to Late Pleistocene. However, circumstantial evidence indicates its significance for early hominin dispersals during Early/Middle Pleistocene from Africa to Island Southeast Asia. The Late Pleistocene/Early Holocene shows an increase in the archaeological record of the Hoabinhian and Anyathian culture, which further demonstrates close affinities with the Southeast Asian record. This paper summarises the lithic industries of the Late Pleistocene/Early Holocene in this region in connection with the adjoining areas of Nepal, Bangladesh and Myanmar.

The prospect that Yucca Mountain may become a repository for high-level radionuclides with especially long half-lives means that the intended waste containment area must be well beyond the reach of the hydrologic system for at least ten millennia. Through the integration of several avenues of paleoclimatic proxy data, the authors intend to arrive at definite conclusions regarding rates of change, and extremes and stabilities of past climate regimes. These will in turn lead to rough estimates of: the amounts of rainfall available for recharge during past periods of effectively wetter climate, and the durations and frequencies of recharge periods. The paper gives summaries of the following studies: Late Quaternary and Holocene climate derived from vegetation history and plant cellulose stable isotope records from the Great basin of western North America; Accomplishments of paleofaunal studies, 1993--1994; Geomorphology studies in the Great Basin; Alluvial fan response to climatic change, Buena Vista Valley, central Nevada; Sedimentology, stratigraphy, and chronology of lacustrine deposition in the Fernley Basin, west-central Nevada; Tree-rings, lake chronologies, alluvial sequences and climate--Implications for Great Basin paleoenvironmental studies; Stable isotopic validation studies--Fossil snails; and Late Pleistocene and Holocene eolian activity in the Mojave Desert.

Cenozoic seismic stratigraphy and geological development of the south Vøring Plateau, Mid-Norwegian margin, are analyzed to understand their relation to fluid flow and margin stability. Regional stratigraphy and palaeomorphology of the Mid-Norwegian margin indicate gradual changes in depositional environment and tectonic compression between 55 Ma and 2.8 Ma, i.e. during deposition of the Brygge and Kai Fms, and also abrupt changes associated with glacial-interglacial cycles from 2.8 Ma when the Naust Fm was deposited. These changes resulted in deposition of various types of sediments and led to processes such as polygonal faulting, formation of contourites and continental shelf progradation. Gas hydrate related bottom simulating reflectors (BSR) occur at Nyegga and within the central Vøring Basin while pockmarks are observed at Nyegga only. The BSRs are concentrated above Eocene depocenters, in hemipelagic and contouritic sediments deposited during Late Plio-Pleistocene. They overly polygonal faults and diagentic reflectors (DBSR) due to Opal A - Opal CT conversion but are confined to the slope of anticlines indicating its formation being related to fluid pathways from methanogenic rocks through focused fluid flow. The DBSRs are located in oozes within the Kai and upper Brygge Fms. We propose a model where fluid expulsion due to DBSR formation and polygonal faulting in oozes created overpressure in permeable layers belonging to the Naust Fm. Slide headwalls are observed close to the anticlines, implying that the over-pressured oozes and the focussed fluid flow may have been important in creating weak surfaces in the Naust deposits, promoting conditions for failures to occur.

Northwestern Green Canyon and Western Ewing Bank lease areas are characterized by complex faulting and salt deformation affecting the late Pliocene-Pleistocene sediments. The sequence stratigraphy has been studied using 1300 km of multifold seismic data, and 40 wells with biostratigraphy data (12 with high-resolution analysis). Fossil abundance and diversity curves were used to recognize condensed sections. Eight depositional sequences have been recognized (2.4, 1.9, 1.4, 0.8, 0.7, 0.5, and 0.4 Ma). Maximum thickness of these sediments is 6 km. Paleobathymetry indicates that sequences were deposited primarily in bathyal water depths. Most of the sediments are in the lowstand systems tracts and consist of basin-floor fans, slope fans, and prograding complexes. Thick blocky sand packages (basin-floor fan) are present in two major sequences (1.4 and 1.1 Ma) and represent potential reservoirs in the area. Transgressive and highstand systems tracts are fairly thin across the area and are thicker only in the younger sequences (Green Canyon Blocks 6, 52, 184, and 228, and are associated primarily with amplitude anomalies on the flanks of salt structures and/or faults.

Although discontinuous because of their karst nature, the Almenara-Casablanca complex records a very complete small vertebrate succession (amphibians, squamates, insectivores, bats, rodents and lagomorphs), characterized by the richness of their sites, a richness which cannot be expected in sites of fluvio-lacustrine origin. This late Neogene-early Quaternary succession includes the sites of Almenara-Casablanca M (Miocene-Pliocene boundary), Almenara-Casablanca 4 (late Pliocene), Almenara-Casablanca 1 (earliest Pleistocene) and Almenara-Casablanca 3 (late early Pleistocene). In this way, the Almenara-Casablanca succession complements the data from other well know terrestrial Pliocene-Pleistocene sequences in the Iberian Peninsula, most notably that of the Guadix-Baza Basin. The complementa...

... driving force behind late Pleistocene musk ox (Ovibos moschatus) population dynamics. ... Metagenomic, phylogenetic, and culture-based analysis of subsurface .... Effects of aridity and vegetation on plant-wax ?D in modern lake sediments.

... driving force behind late Pleistocene musk ox (Ovibos moschatus) population dynamics. ... Metagenomic, phylogenetic, and culture-based analysis of subsurface .... Effects of aridity and vegetation on plant-wax ?D in modern lake sediments.

Lake-level change and landslides are primary controls on the development of coastal environments along the coast of northeastern Lake Michigan. The late Quaternary geology of Sleeping Bear Dunes National Lakeshore was examined with high-resolution seismic reflection profiles, ground-penetrating radar (GPR), and boreholes. Based on sequence-stratigraphic principles, this study recognizes ten stratigraphic units and three major unconformities that were formed by late Pleistocene glaciation and postglacial lake-level changes. Locally high sediment supply, and reworking by two regressions and a transgression have produced a complex stratigraphy that is prone to episodic failure. In 1995, a large landslide deposited approximately 1 million m3 of sediment on the lake floor. The highly deformed landslide deposits, up to 18 m thick, extend 3-4 km offshore and unconformably overlie well-stratified glacial and lacustrine sediment. The landslide-prone bluff is underlain by channel-fill deposits that are oriented nearly perpendicular to the shoreline. The paleochannels are at least 10 m deep and 400 m wide and probably represent stream incision during a lake-level lowstand about 10.3 ka B.P. The channels filled with sediment during the subsequent transgression and lake-level highstand, which climaxed about 4.5 ka B.P. As lake level fell from the highstand, the formation of beach ridges and sand dunes sealed off the channel and isolated a small inland lake (Glen Lake), which lies 5 m above the level of Lake Michigan and may be a source of piped groundwater. Our hypothesis is that the paleochannels act as conduits for pore water flow, and thereby locally reduce soil strength and promote slope failure.

As part of the German R/V Meteor M67/2 expedition in 2006 to the southern Gulf of Mexico, a set of 2D high resolution seismic profiles was acquired across the Chapopote knoll to study sea floor asphalt occurrences and their origin. Based on regional seismic stratigraphy studies, correlated to DSDP sites, a higher reflective coarse grained sediment unit of Late Miocene age is identified as a potential shallow gas reservoir, overlain by a low permeability fine grained Pliocene and Pleistocene cover. As a result of salt diapirism, local uplift has caused reduced accumulation rates above the diaper since the late Pliocene, while the rates had been uniform throughout the area before. This has further improved the seal properties, since more fine grained material deposited in elevated locations. Nevertheless, on the crest of Chapopote, sediments above the coarse sediment unit are only around 150-75 m thick. Since oil and gas production can well be expected at depth in Jurassic and Tertiary source rocks, the presence of high amplitude reflector packages within the reservoir unit is interpreted as a result of the presence of hydrocarbons. This interpretation is further supported by the observation that some reflectors are cross-cutting and/or reveal a drop in instantaneous frequency. But, the thin seal above the reservoir unit, located directly underneath a widespread occurrence of asphalts at the sea floor, probably facilitates the leakage of hydrocarbons trapped inside the reservoir through a ~ 750 m wide acoustically chaotic zone partly aided by faulting. Since the top of Chapopote shows a high structural complexity, more seepage sites may exist beyond where seafloor asphalts have been found so far. Evolution and structure of the migration and reservoir system, which may be deep rooted, will be discussed both with respect to shallow gas and asphalt occurrences.

Quaternary temperate stages have long been described based on changing pollen abundances of various tree taxa in lacustrine sediments. Later, attempts have been made to assign such biostratigraphic units to distinct marine isotope stages (MIS). Existing continuous chronosequences from Southern 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 from Northern-Central Europe and evaluate the usefulness of several numerical techniques. TWINSPAN analysis identifies groupsof temperate stages based on presence/absence of their indicative taxa and may be useful for distinguishing between older and younger interglacials. Site-to-site sequence slotting allows the determination of the most similar pairs of records, based on sample dissimilarity following their stratigraphic constraints. Sequence slotting performs well when correlating the Holsteinian interglacial and Cromerian stage II, and also provides tentative correlation of some problematic records. Ordination compares main trends in pollen stratigraphies of all pollen sequences. It finds very similar patterns between Eemian records and Cromerian stage II. Although different methods show sometimes inconsistent results, they can certainly contribute to the discussion of the age of poorly known interglacials. The implications for future directions suggest focusing on better sampling resolution, multi-proxy approaches to climatic reconstruction and obtaining better independent dating.

Knowledge on past variability of sedimentary organic carbon in the Arctic Ocean is important to assess natural carbon cycling and transport processes related to global climate changes. However, the late Pleistocene oceanographic history of the Arctic is still poorly understood. In the present study we show sedimentary records of total organic carbon (TOC), CaCO3, benthic foraminiferal ?18O and the coarse grain size fraction from a piston core recovered from the northern Northwind Ridge in the far western Arctic Ocean, a region potentially sensitively responding to past variability in surface current regimes and sedimentary processes such as coastal erosion. An age model based on oxygen stratigraphy, radiocarbon dating and lithological constraints suggests that the piston core records paleoenvironmental changes of the last 155 kyr. TOC shows orbital-scale increases and decreases that can be respectively correlated to the waxing and waning of large ice sheets dominating the Eurasian Arctic, suggesting advection of fine suspended matter derived from glacial erosion to the Northwind Ridge by eastward flowing intermediate water and/or surface water and sea ice during cold episodes of the last two glacial-interglacial cycles. At millennial scales, increases in TOC might correlate to a suite of Dansgaard-Oeschger Stadials between 120 and 45 ka before present (BP) indicating a possible response to abrupt northern hemispheric temperature changes. Between 70 and 45 ka BP, closures and openings of the Bering Strait could have additionally influenced TOC variability. CaCO3 content tends to anti-correlate with TOC on both orbital and millennial time scales, which we interpret in terms of enhanced sediment advection from the carbonate-rich Canadian Arctic via an extended Beaufort Gyre during warm periods of the last two glacial-interglacial cycles and increased organic carbon advection from the Siberian Arctic during cold periods when the Beaufort Gyre contracted. We propose that this pattern may be related to orbital- and millennial-scale variations of dominant atmospheric surface pressure systems expressed in mode shifts of the Arctic Oscillation.

The Moringa Cave within Pleistocene sediments in the En Gedi area of the Dead Sea Fault Escarpment contains a sequence of various Pleistocene lacustrine deposits associated with higher-than-today lake levels at the Dead Sea basin. In addition it contains Chalcolithic remains and 5th century BC burials attributed to the Persian period, cemented and covered by Late Holocene travertine flowstone. These deposits represent a chain of Late Pleistocene and Holocene interconnected environmental and human events, echoing broader scale regional and global climate events. A major shift between depositional environments is associated with the rapid fall of Lake Lisan level during the latest Pleistocene. This exposed the sediments, providing for cave formation processes sometime between the latest Plei...

The stratigraphy of the Farasan Islands (Pliocene?Pleistocene deposits) is established on the basis of a detailed study of six stratigraphic sections described and sampled in the field. Detailed examinations involve the microfacies analyses and identification of macrofossils makes it possible to determine two new informal formations, namely, from the base to the top: Esbah formation of Pliocene age and Farasan formation of Pleistocene age. The detected microfacies types of the studied samples are only carbonate facies and include five major types: mudstone, wackestone, packstone, floatstone and boundstone. No grains of quartz sand or igneous mineral were found in the islands. The nomenclature of the biostratigraphic units established in the present work is not intended to define world-wide...

Greenstone sucessions are defined as the nongranitoid component of granitoid-greenstone terrain and are linear to irregular in shape and where linear are termed belts. The chemical composition of greenstones is described. Also discussed are the continental environments of greenstone successions. The effects of contact with granitoids, geophysical properties, recumbent folds and late formation structures upon greenstones are examined. Large stratigraphy thicknesses are explained.

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.

A model that describes the distribution of calcium carbonate in desert soils as a function of dust flux, time, climate, and other soil-forming factors shows which factors most strongly influence the accumulation of carbonate and can be used to evaluate carbonate-based soil age estimates or paleoclimatic reconstructions. Models for late Holocene soils have produced carbonate distributions that are very similar to those of well-dated soils in New Mexico and southern California. These results suggest that (1) present climate is a fair representation of late Holocene climate, (2) carbonate dust flux can be approximated by its Holocene rate, and (3) changes in climate and/or dust flux at the end of the Pleistocene effected profound and complex changes in soil carbonate distributions. Both higher carbonate dust flux and greater effective precipitation are required during the latest Pleistocene-early Holocene to explain carbonate distributions in latest Pleistocene soils. 21 refs., 4 figs., 1 tab.

Hall’s Cave, Kerrville County Texas, 167 km WSW of Austin, provides a unique opportunity for testing the presence of a chronostratigraphic datum (YDB layer) containing rare and exotic proxies, including nanodiamonds, aciniform soot, and magnetic spherules, the origins of which remain controversial, but possibly derive from a cosmic impact ~12,900 CAL BP. The karst-collapse cave in Cretaceous limestone on the Edwards Plateau contains ? 3.7 m of stratified clays grading to clayey silts recording continuous deposition from 16 ka RC yr to present. The cave’s small catchment area and mode of deposition were constant, and the stratigraphy is well dated based on 162 AMS 14C dates from individual vertebrate fossils, snails, charcoal, and sediment chemical fractions. The cave sequence contains an abundant small animal vertebrate fossil record, exhibiting biostratigraphic changes, and the timing of the late Pleistocene megafaunal extinction is consistent with that elsewhere in North America. At 151 cm below datum is the extremely sharp, smooth contact separating lower, dusky red (2.5YR3/2) clays below from overlying dark reddish brown (5YR3/3) clays (forming a 20-cm-thick dark layer) and dating to 13,000 CAL BP, at or close to the age of the YDB datum elsewhere. This appears to be the most distinctive lithologic change of the deglacial sequence. Sediments at or within 10 cm of this contact contain the local extinction of 4 species of bats, the local extinction of the prairie dog (Cynomys sp.) and perhaps other burrowing mammals in response to decrease in soil thickness, and the uppermost occurrence of 6 late Pleistocene megafaunal taxa that, although rare in the cave, do not extend younger than 12.9 ka. We collected and analyzed sediments at high resolution above and below the distinct lithologic contact at 151 cm. The red clays from 151 to 153 cm and immediately preceding the lithologic contact contain an abundance of nanodiamonds (5 different allotropes), aciniform soot at 2400 ppm, magnetic spherules, and carbon spherules, all of which we interpret as evidence for a unique chronostratigraphic marker (YDB) in the Western Hemisphere. Because the age of this horizon is ~ 13,000 CAL BP, we interpret the age of the event as the beginning of the Younger Dryas cooling. Regional soil erosion began ~15,000 CAL BP and continued until 7000 CAL BP, but dating suggests that there is no discontinuity or hiatus in deposition, and thus, the exotic materials in that layer are not considered to be erosional accumulations. Future analyses include sub-centimeter sampling over the YD boundary, quantification of nanodiamonds and other event-proxies within 1000 yr of the boundary and in sediments several 1000 years older and younger, continued refinement of the AMS 14C record to determine within 50 yr the location of 12,900 CAL BP datum and high resolution analysis of small animal biostratigraphy.

Certain details regarding the origin and evolution of shelf sand ridges remain elusive. Knowledge of their internal stratigraphy and microfossil distribution is necessary to define the origin and to determine the processes that modify sand ridges. Fourteen vibracores from False Cape Shoal A, a well-developed shoreface-attached sand ridge on the Virginia/North Carolina inner continental shelf, were examined to document the internal stratigraphy and benthic foraminiferal assemblages, as well as to reconstruct the depositional environments recorded in down-core sediments. Seven sedimentary and foraminiferal facies correspond to the following stratigraphic units: fossiliferous silt, barren sand, clay to sandy clay, laminated and bioturbated sand, poorly sorted massive sand, fine clean sand, and poorly sorted clay to gravel. The units represent a Pleistocene estuary and shoreface, a Holocene estuary, ebb tidal delta, modern shelf, modern shoreface, and swale fill, respectively. The succession of depositional environments reflects a Pleistocene sea-level highstand and subsequent regression followed by the Holocene transgression in which barrier island/spit systems formed along the Virginia/North Carolina inner shelf not, vert, ~5.2 ka and migrated landward and an ebb tidal delta that was deposited, reworked, and covered by shelf sand.

Concentrations of noble gases, stable isotopes and 14C in samples from the Continental Terminal groundwaters of Niger provide evidence for more humid and cooler climate phases in West Africa in the Holocene and the late Pleistocene. During humid phases, even within the Holocene, the soil temperature...

Under suitable conditions the colors and patterns of the shells of land snails may be preserved for thousands of years. In a late Pleistocene population of Limicolaria martensiana all the major color forms that occur in modern living snails may be distinguished, and the basic polymorphism is at least 8,000 to 10,000 year old. PMID:17830234

Situated at the southeast magrin of the Mu Us Desert, the Milanggouwan stratigraphical section in the Salawusu River Valley records 27 depositional sequences of the aeolian dune layers alternating with the fluvio-lacustrine facies and palaeosols from the Late Pleistocene to Holocene. Grain-size anal...

The long-standing controversy regarding the late Pleistocene megafaunal extinctions in North America has been invigorated by a hypothesis implicating a cosmic impact at the ?llerød-Younger Dryas boundary or YDB (?12,900 ± 100 cal BP or 10,900 ± 100 14C years). Abrupt ecosystem disruption caused by t...

Central Oregon exhibits both extensive active faulting and Quaternary volcanism, yet the relations between them are complex and poorly constrained. The N15W striking North Christmas Valley fault system is a Basin and Range type structure offsetting High Lava Plains volcanics forming a ~3 km wide graben that bounds Christmas Lake. Several young volcanic vents, including Green Mountain (GM), Four Craters (4C), and East Lava Field, are aligned parallel with and bounded by the graben. We focus on Crack-in-the-Ground (CITG) fault which vertically displaces the GM and FC basalts. The GM basalt is dated at 740 +/- 59 ka by 40Ar/39Ar (Jordan, 2002). Our preliminary dating of the 4C basalt yields an average age of 12 +/- 2 ka, determined by cosmogenic 3He exposure dating of olivine from flow surfaces. Since emplacement of the GM basalts, the fault has developed a ~10 m hanging wall monocline and a vertical hinge crack which yields the 0.013 mm/yr slip rate suggested in Jordan (2002). The 4C basalt has also been cracked by the CITG fault, producing a 30 +/-10 cm vertical offset. A trench excavated across a section of CITG exposed the stratigraphy of the upper 2.25 m. The upper 1.25 m is a modern soil developed on ~7 ka Mt. Mazama ash. The whole unit is offset ~12 cm as the result of a presumed co-seismic graben structure in the crack. The lower one meter is a palesol developed on windblown sandy silt. The 4C cinder cones may have produced a basaltic tephra that is not seen in the trench, therefore we think the lower unit is post-4C. The paleo-surface has a shallow east dip caused by co-seismic deformation. The two events seen in the trench are likely post-4C, suggesting the 4C offset is cumulative between two events, yielding a slip rate of 0.025 mm/yr. Comparison of the two slip rates suggests an increased slip rate post-4C. Our results are consistent with a potential volcano-tectonic relationship in which slip rate increased during the Late Pleistocene associated with volcanism of the High Lava Plains.

The Kashi foreland basin in NW China contains >8 km of syn-tectonic sediments related to uplift and deformation along the southern margin of the Tian Shan during late Tertiary time. Foreland deposits consist of fine-grained, gypsiferous, lacustine beds (Wuqia Group) near the base that grade up-section into fluvial sandstone and siltstone (Atushi Fm.), with the fluvial Xiyu Conglomerates capping the basin sequence. The distinctive Xiyu Conglomerates form a wedge that thins and interfingers with silt and sand ubiquitously towards the south (distal basin) and locally east-west. The Xiyu Formation is widely distributed around the margin of the Tian Shan, and has been inferred to represent Plio-Pleistocene initiation of deformation of the Tian Shan (e.g. Huang et al., 1980), or a change in either climate (e.g. Burchfiel et al., 1999; Molnar et al., 1994) or a climate-affected erosion rate (Zhang et al, 2001). In contrast, our data show that the Xiyu conglomerates are a time-transgressive formation that has continuously prograded south since at least ~16 Ma, and likely does not represent a distinct climatic or tectonic event from one time period. Eight magnetostratigraphic sections totaling 10,000 m of vertical section through the entire basin sequence, and correlated with the Geomagnetic Polarity Timescale of Cande and Kent (1995), indicate continuous deposition between 0 and ~18 Ma. Paleocurrent data from throughout the basin are consistent with longitudinal drainages moving south as transverse (north-to-south), braided, fluvial systems encroach on the foreland. Clast size, sorting, and composition are consistent with initial unroofing of Paleozoic source rocks to the north, and subsequent re-working and erosion of this conglomerate during progradation into the foreland in concert with a migrating deformation front. Deposition rates increase from <200m/Myr in the early to middle Miocene to ~800 m/My during the Pliocene. These sedimentary data, combined with an 18+/-3 Ma fission track age from the hanging wall of the basin-bounding thrust fault (KBT), indicate that deposition in the Kashi basin began at ~18 Ma. The basin age of 18 Ma is younger than fission-track ages (ca. 25 Ma) from the major range bounding faults ~ 20 km north of the KBT. Thus, the stratigraphy and thermochronolgy support continuous and generally accelerating deposition in the Kashi foreland basin since 18 Ma related to uplift on the KBT, and a syn-tectonic origin for the time-transgressive Xiyu conglomerate. Prior to 18 Ma, the flexural foreland may have lain farther to the north.

The Barents Sea has experienced profound glacial erosion during the late Pliocene and Pleistocene which resulted in the development of a characteristic glacial morphology of the continental shelf and deposition of a several km thick sediment wedge/fan along the western margin prograding into the deep sea. During the middle and late Pleistocene, glacial erosion was most severe beneath the paleo-ice streams of the Barents Sea Ice Sheet and affected mainly the trough areas (~200.000 km2). The total erosion is estimated to 435 - 530 m, the average erosion 0.6 - 0.8 mm/yr and the average sedimentation rates on the continental slope were 18 - 22 cm/kyr. The first-order control on the amount of erosion was probably the glaciations duration and velocity of the ice streams. Erosion by paleo-ice streams affected a larger area (~575.000 km2) during the early and middle Pleistocene because they were less topographically stable due to a less pronounced paleo-relief. Also, glaciotectonism was more extensive during this period. The total erosion was estimated to 330 - 420 m and the average erosion 0.4 - 0.5 mm/yr. The average sedimentation rates were 50 - 64 cm/kyr, 2 - 3 times higher than during the succeeding period. In the late Pliocene - early Pleistocene period, proglacial processes including glacifluvial erosion dominated. The total erosion was found to be 170 - 230 m, the average erosion 0.15 - 0.2 mm/yr and the average sedimentation rates were 16 - 22 cm/kyr. In total, the glacial erosion of the troughs has been relatively high throughout the late Pliocene - Pleistocene period, about 1000 - 1100 m. For the banks the erosion is inferred to have increased from late Pliocene to peak in early - middle Pleistocene, later there has been little erosion in these areas which implies a total of 500 - 650 m of erosion. The average glacial erosion during the whole late Pliocene and Pleistocene period is 38 cm/kyr, one order of magnitude higher than the average glacial erosion of the east Greenland continental shelf. This demonstrates that there have been large variations in the glacial erosion affecting the northern, high-latitude continental margins. Acknowledgement This work is a contribution to the project; Ice ages: subsidence, uplift and tilting of traps: the influence on petroleum systems (GlaciPet) funded by the Research Council of Norway and Statoil.

Morphostratigraphic and sedimentological studies were undertaken in the Cap Bon peninsula, north-eastern Tunisia. These studies have identified a series of middle to late Pleistocene?age marine deposits discontinuously cropping out on three raised platforms (Pf I, Pf II and Pf III). These stepped marine platforms (terraces) were related to the interplay between Pleistocene sea-level changes and progressive uplift movement during Quaternary period. We present here a description of facies organization and stratigraphic characteristics of the platform deposits, and their relation with eustatic and climatic variations. All the marine platforms unconformably overlie a Mio-Pliocene and Quaternary slope succession. The sedimentary sequences represented by mixed carbonate and siliciclastic bodies ...

Jeju Island is the emergent portion of a basaltic volcanic field developed over the last c. 1.8Ma on continental crust. Initial volcanism comprised dispersed, small-volume (1km^3) eruptions began, with lavas building a composite shield. Three magma suites can be recognized: Early Pleistocene high-Al alkali (HAA), and Late Pleistocene to Holocene low-Al alkali (LAA) and subalkali (SA). The chemical similarity between small-volume and primitive large-volume eruptions suggests analogous parent magmas and fractionation histories that are independent of erupted volumes. The large-volume magmas ev...

The skull of a mummy horse from the Late Pleistocene of the western Chukchi Peninsula is described. This is the seventh horse mummy recorded during the past 150 years in the Pleistocene permafrost of Siberia. Because of unique preservation (the skeleton is covered by soft tissues and skin) and young individual age (1?1.5 years of age), it is presently impossible to provide its correct species allocation of this specimen. Morphological features of the skull proportions and dentition of the Bilibino horse apparently reflect both species and individual characteristics of the structure and development.

New shallow scientific drillcore has been recovered through the Frasnian-Famennian extinction boundary in northwest Australia’s Canning Basin. Previous work in the McWhae Ridge outcrop belt has identified patterns of turnover in trilobites and other fauna, change from sponge- and coral-dominated reefs to post-extinction microbial-dominated reefs, apparent sea level changes, and carbon isotopic evidence of late Devonian crisis. Continuous magnetic susceptibility (MS) stratigraphy yields highly structured oscillations spanning ~42 m of reef-slope carbonate. These oscillations appear to identify late Frasnian “Kellwasser” events and they may record sedimentary response to orbital variations, establishing a high-resolution relative chronostratigraphy of late Devonian global change. Magnetic susceptibility stratigraphy has been proposed as a generally useful chronometer for late Devonian time. Most of fifteen published MS stratigraphies crossing the Frasnian-Famennian boundary appear to share major excursions with the new McWhae Ridge result. Although upland tectonism in Canning Basin may be a caveat to straightforward eustatic interpretation of magnetic susceptibility variations, we suggest the higher-resolution and fresh drillcore context of this result prioritizes it as a standard for Frasnian-Famennian magnetic susceptibility variation.

Abstract in spanish El sistema de rifts del norte del Golfo de California consiste en una serie de fallas que acomodan tanto deformación normal como de rumbo. Las fallas que lo integran generaron semigrábenes que fueron rellenados por más de siete kilómetros de sucesiones siliciclásticas profundamente cíclicas a varias escalas de tiempo. La cronoestratigrafía de las cuencas indica que la subsidencia inició en el Mioceno medio (~15 Ma). En este trabajo presentamos modelos tectonosedim (more) entarios para la cuenca Tiburón, en la parte sur del sistema, y la cuenca Wagner, en la parte norte. Los modelos están constreñidos por perfiles sísmicos 2D y por la estratigrafía de dos pozos profundos adquiridos por PEMEX-PEP. Los modelos son cinemáticos e incorporan los efectos de deformación por fallamiento, flexión, compactación y redistribución de masa por erosión y sedimentación. El análisis de las líneas símicas y los resultados del modelado muestran que: (i) la subsidencia está controlada por fallas normales de alto ángulo y por flujo de la corteza inferior, (ii) las cuencas comparten una historia de subsidencia común y (iii) la manera como la deformación fue acomodada en las cuencas varía considerablemente, algo típico de ambientes rifts. Las fallas que limitan a la cuenca Tiburón tienen una geometría anidada, forman un semigraben con caída al E y su secuencia de activación fué W-E. La estructura fue creada en dos pulsos de actividad de fallas. Uno está relacionado con la fase de extensión del protogolfo y el segundo con la fragmentación de Baja California durante el Pleistoceno. La cuenca Wagner, por otra parte, tiene una historia más compleja. Es producto de dos generaciones de fallas. La fase de extensión del protogolfo dio origen a dos semigrábenes limitados por las fallas de Cerro Prieto y San Felipe. Esas fallas tienen un arreglo en dominó y caída hacia el W. En una segunda fase de extensión las fallas del sistema de Consag y Wagner formaron la depresión que alberga a la cuenca Wagner moderna. Abstract in english The northern Gulf of California rift system consists of a series faults that accommodate both normal and strike-slip motion. The faults formed a series of half-grabens filled with more than 7 km of deeply cyclical siliciclastic successions. The chronostratigraphy of the basins shows that subsidence started during the middle Miocene (~15Ma). Here, wepresent tectonostratigraphic models for the Tiburón basin, in the southern part of the system, and the Wagner basin in the n (more) orth. The models are constrained by two-dimensional seismic lines and by the stratigraphy of two deep boreholes drilled by PEMEX-PEP. Models are kinematic and incorporate the effects of faulting, flexure, sediment compaction and redistribution of mass by the combined efects of erosion and sedimentation. Analysis of the seismic lines and models' results show that: (i) subsidence of the basins is controlled by high-angle normal faults and by flow of the lower crust, (ii) basins share a common history, and (iii) there are significant differences in the way brittle strain waspartitioned in the basins, afeature frequently observed in rift basins. On one hand, the bounding faults of the Tiburón basin have a nested geometry and became active following a west-to-east sequence of activation. The Tiburon half-graben was formed by two pulses offault activity. One tookplace during the protogulf extensionalphase in the Miocene and the other during the opening of Gulf of California in the Pleistocene. On the other hand, the Wagner basin is the result of two fault generations. During the late to middle Miocene, the west-dipping Cerro Prieto and San Felipe faultsformed a domino array. Then, during the Pleistocene the Consag and Wagnerfaults dissected the hanging-wall of the Cerro Prieto fault forming the modern Wagner basin.

A mass extinction affected South America during the late Pleistocene and early Holocene, when megamammals and large mammals disappeared. Several carnivores became extinct, including the sabretooth (Smilodon), the short-faced bear (Arctotherium), and some large canids (i.e., Protocyon, Canis dirus). After this mass event, virtually no carnivores became extinct in South America. The only exception is the fox Dusicyon avus, a medium-sized canid (estimated body mass between 10 and 15 kg) with a more carnivorous diet than the living South American foxes (Lycalopex culpaeus). The last record of the species comes from middle-late Holocene archaeological sites in the Pampean Region (Argentina) and Patagonia (Argentina and Chile). During the late Pleistocene, D. avus had a wide distribution, which ...

Knowledge of the Early-Middle Pleistocene (Ensenadan Age/Stage ; ca. 1.8-0.4 Ma) South American Glyptodontidae (Cingulata) is still poor compared with the Late Pleistocene-Early Holocene taxa (Lujanian Age/Stage). This is especially true for the Glyptodontidae Panochthini, in which it is possible to recognize two Ensenadan species from the Pampean region of Argentina, Panochthus intermedius and P. subintermedius, known only by their type material. Prior to this contribution, the knowledge of P. intermedius, a taxon with biostratigraphic importance for being considered as a guide taxon of the Ensenadan Age/Stage of South America, was limited to a dorsal carapace. The finding of an exceptional almost complete specimen from the Early-Middle Pleistocene of Bolivia has allowed us to greatly imp...

We used cummingtonite chemistry to detect strongly weathered widespread cryptotephras within middle Pleistocene loess and fluvial terrace deposits and to correlate them with previously reported tephras in central and NE Japan. We correlated a cummingtonite-bearing cryptotephra widely distributed in NE Japan below the Ichihasama Pumice (108-146ka) and above the Iwadeyama Pumice (IwP, 160-240ka) with the Iizuna-Kamitaru c tephra (Iz-KTc), which erupted from Iizuna volcano, central Japan. Iz-KTc is thus a widespread middle Pleistocene tephra covering both central and NE Japan. Moreover, we detected the Adachi-Medeshima tephra (Ac-Md), which had been previously inferred to be a late Pleistocene tephra (80-100ka), below the Iz-KTc and IwP tephras (125-150ka) and above the Hagimori White Ash tep...

A beachrock correlative with the Ingleside complex of the late Pleistocene Beaumont Formation crops out discontinuously along the mainland shore of Laguna Madre, extending approximately 10 km southward from Baffin Bay, Texas. Carbon-14 dating yields ages of 23, 430 to 33,390 yrs. B.P.; the beachrock formed along a Gulf shoreline in a zone of converging longshore currents during the last sea level highstand of the late Wisconsinan. The beachrock shows intense karstification. Vertical, steep-walled solution pipes penetrate the outcrops, and reddish-brown laminated caliche crusts coat outcrop surfaces and solution-pipe walls in many places. These karst features probably formed by subaerial exposure and weathering of the beachrock during the latest sea level lowstand. Today in semiarid South Texas, rainfall averages only 28 inches per year. Local features of late Pleistocene age include river gravels coarser than modern loads of those same rivers, and relict drainage networks far denser than modern ones. Such features indicate that during the late Pleistocene this region was more humid than now. Karst is typical of humid to subhumid climates, also suggesting that during karstification of the beachrock wetter climates prevailed.

Palynological records from the Congo fan reveal environmental change in equatorial Africa occurring 1.05 Ma ago, 100 k.y. before the mid-Pleistocene climatic shift at 0.9 Ma. Prior to 1.05 Ma, a glacial-interglacial rhythm is not obvious in the African vegetation variation. Afterwards, Podocarpus spread in the mountains of central Africa mainly during glacials and Congo River discharge decreased. The sequence of vegetation variation associated with the mid-Pleistocene glacials and interglacials differed from that observed during the late Pleistocene. Between 0.9 and 0.6 Ma, interglacials were characterized by warm dry conditions and glacials were characterized by cool humid conditions, while during the past 0.2 Ma glacials were cold and dry and interglacials warm and humid. Our data indicate that before the Northern Hemisphere ice caps dramatically increased in size (0.9 0.6 Ma), low-latitude climate forcing and response in the tropics played an important role in the initiation of 100 k.y. ice-age cycles. During the mid to late Pleistocene, however, the climate conditions in the tropics were increasingly influenced by the glacial-interglacial variations of continental ice sheets.

The Great Basin of arid western North America provides one of the most detailed late Pleistocene and Holocene mammal records available for any part of the world, though the record is by far strongest for small mammals. Of the 35 genera of now-extinct North American Pleistocene mammals, 19 are known to have occurred in the Great Basin, a list that is likely to be complete or nearly so. Of these 19, seven can be shown to have survived beyond 12,000 radiocarbon years ago, a proportion similar to that for North America as a whole. Horses, camels, mammoth, and helmeted musk-oxen appear to have been the most abundant of these genera. Pygmy rabbits (Brachylagus idahoensis), yellow-bellied marmots (Marmota flaviventris), and bushy-tailed woodrats (Neotoma cinerea) declined in abundance at the end of the Pleistocene, at about the same time as populations south of their current arid western distributional boundary were extirpated. Subsequent declines occurred during the hot/dry middle Holocene. Pygmy rabbits also declined as modern pinyon-juniper woodlands developed across the Great Basin. The Snake Range of eastern Nevada has seen the late Pleistocene or Holocene extinction of both northern pocket gophers (Thomomys talpoides) and pikas (Ochotona princeps). Coupled with the rarity of yellow-bellied marmots here, these histories make the Snake Range a biogeographic oddity. These and other Great Basin mammal histories provide significant insights into the possible responses of Great Basin small mammals to global warming.

The site of Bonneval (France) exhibits a 6m thick stratigraphical sequence in which Middle and Lower Palaeolithic artefacts were discovered. The stratigraphy of the site consists of an alternation of loess-like silt layers deposited along glacial stages, and paleosoil horizons corresponding to the vegetal stabilization of the area during interglacials. These layers hence provide past environmental informations and can be used as stratigraphical markers and compared with well dated sequences of Northern France. Eight sediment samples from this Middle and Upper Pleistocene sequence were dated using the recuperated optically stimulated luminescence (Re-OSL) signal of quartz grains. The middle-size fraction (40-63mm) shows a good reproducibility of the OSL signals which allows the application ...

The nannofosssil assemblages have been analyzed in five cores taken from the Titanic area of the northwestern Atlantic (?41??42? N, ?47??50? W, water depths >3500 m) during cruises 41 and 43 of the R/V Akademik Mstislav Keldysh in 1998 and 2000. They correlate the host sediments with the upper Pleistocene-Holocene Emiliania huxleyi zone. The changes in the structure of the nannofossil assemblages and the lithological characteristics such as the content of biogenic CaCO3, the abundance of ice-rafted debris, and the grain-size composition were used for the high-resolution stratigraphy of sections with defining marine isotopic stages 1?3 of the last 24 kyr. A characteristic feature of the nannofossil assemblages from this area is their enrichment with the cold-resistant species Coccolthus pel...

This review deals only with the evolutionary history of core Arctic marine mammals: polar bear (Ursus maritimus), walrus (Odobenus rosmarus), bearded seal (Erignathus barbatus), harp seal (Pagophilus groenlandica), ringed seal (Phoca hispida), bowhead whale (Balaena mysticetus), white whale (Delphinapterus leucas), and narwhal (Monodon monoceras). Sections on the evolutionary background of pinnipeds and whales help to provide a better perspective on these core species. Polar bears stemmed from brown bears about the Early to Middle Pleistocene. Fossils are rare; the earliest records are from approximately Early Weichselian deposits of Kew Bridge, London, and Svalbard. Existing Pacific and Atlantic walruses probably arose from splitting of a former Holarctic range during a Pleistocene glacial phase of extensive sea ice in the Canadian Arctic. The earliest known bearded seal remains are from Early to Middle Pleistocene deposits of Norfolk, England, and Cape Deceit, Alaska. Other Pleistocene fossils of this species are recorded from the North Sea, southwestern Sweden, and the Champlain Sea that existed in eastern North America approximately 12 000-10000 BP. The harp seal is the commonest pinniped in the Weichselian deposits of the southern North Sea. The earliest recorded fossil is from about 2 million years ago (2 Ma), from Ocean Point, Alaska. The earliest known Pleistocene ringed seal fossils are from last interglacial deposits near Teshekpuk Lake, Alaska, and Thule, Greenland, although an earlier (3 Ma?) specimen from Malaspina, Alaska, has been reported. This species seems to have been relatively abundant along the coasts of Prince of Wales Island, Alaska, during the Last Glacial Maximum. The bowhead whale probably originated in the high latitudes of the Northern Hemisphere. The earliest (mid-Wisconsinan) Canadian remains are from Ellesmere and Devon islands. More than 400 radiocarbon-dated bowhead remains have been used to reconstruct Holocene sea ice history in the Canadian Arctic. White whales are common in the late warming stage (approximately 10 500 BP) of the Champlain Sea and are one of the commonest marine mammal fossils in Late Pleistocene North Sea deposits. Fourteen narwhal specimens of Late Glacial or Early Holocene age are known from Atlantic Canada, as well as Ellesmere, Baffin, and Prince of Wales islands in Arctic Canada. Arctic marine mammals have tended to shift to more southerly ranges during glacial phases of the Pleistocene. PMID:18494361

A new sedimentary morphogenic analysis was carried out at the Divje babe I Paleolithic site to determine paleotemperatures for Late Pleistocene deposits (around 80,000-40,000 BP) and to discover hiatuses in the sedimentary sequence. The Divje babe I paleotemperature record is based on the relative abundance of congelifracts in a 280cm thick sedimentary sequence. Congelifracts are clasts whose morphogenesis is directly associated with post-depositional frost wedging. The Divje babe I paleotemperature record compares well with global GRIP (Summit) and other regional paleotemperature records for the Late Pleistocene. Comparisons are supported by ESR dates from the Divje babe I site. Two significantly cool climate phases were identified in the Divje babe I record. The older cool phase was plac...

The travertines on which the ancient town of Paestum was built about 2,600?years ago, have been investigated to restore the original sedimentary environment of these freshwater limestones formed during the Late Pleistocene?Holocene in the southern sector of the Sele River plain. For this purpose, the few present outcrops of travertine have been analysed from a palaeoenvironmental point of view, integrating the morphology and the sedimentology of the substrate with the information on the textural patterns of the blocks forming the town walls, some of which have a clear similarity with the outcropping substrate. The Paestum travertines can be distinguished into two sedimentary units: the lower Paestum travertines (LPT) which formed between Late Pleistocene (75,000?years BP) and the Early Hol...

Late Pleistocene Ice Age Crocuta crocuta spelaea (Goldfuss, 1823) hyenas from the open-air gypsum karst site Westeregeln (Saxony-Anhalt, central Germany) is dated into the early to middle Late Pleistocene. Hyena clans apparently used the karst for food storage and as "commuting den", where typical high amounts (15% of the NISP) of hyena remains appear, also faecal pellets in concentrations for den marking purposes. Additionally small carnivores Meles, Vulpes and Mustela appear to have used some cavities as dens. Several hundreds of lowland "mammoth steppe fauna" bones (NISP = 572) must have been accumulated primarily by hyenas, and not by Neanderthals at the contemporary hyena/human camp site. Abundant caballoid horse remains of "E. germanicus Nehring, (1884)" are revised by the holotype a...

Botanical analyses of fossil and modern arctic ground squirrel (Urocitellus parryii) caches and nests have been used to reconstruct the past vegetation from some parts of Beringia, but such archives are understudied in Alaska. Five modern and four fossil samples from arctic ground squirrel caches and nests provide information on late Pleistocene vegetation in Eastern Beringia. Modern arctic ground squirrel caches from Alaska's arctic tundra were dominated by willow and grass leaves and grass seeds and bearberries, which were widespread in the local vegetation as confirmed by vegetation surveys. Late Pleistocene caches from Interior Alaska were primarily composed of steppe and dry tundra graminoid and herb seeds. Graminoid cuticle analysis of fossil leaves identified Calamagrostis canadensi...

Glacial and fluvioglacial landforms and deposits preserved in the middle reaches of the Maruia valley, southeast Nelson, New Zealand, record the activity of the Maruia glacier during the late Pleistocene Otira Glaciation. Five advances are recognised, from oldest to youngest: Creighton 1, 2, 3, and the Reid Stream 1, 2 advances. There was an interstadial interval between the Creighton 3 and Reid Stream 1 advances. The Reid Stream 1 advance occurred shortly after 14,800 years B.P.

Recent glaciological evaluation and modeling of the marine-based West Antarctic Ice Sheet (WAIS) support the possibility that the WAIS disintegrated during one or more Pleistocene interglacial period(s). The magnitude of sea level and oxygen isotope variation during certain late-Pleistocene interglacial periods is also consistent with the possibility of major retreat of the WAIS. Although oxygen isotopes from deep-sea sediments provide the best available proxy record for global ice volume (despite the ambiguities in the record), the source of ice volume changes must be hypothesized. Based on the intensity of interglacial isotopic shifts recorded in Southern Ocean marine sedimentary records, stage 11 (400,000 years ago) is the strongest candidate for WAIS collapse, but the records for stages 9, 7, and 5.5 are all consistent with the possibility of multiple late-Pleistocene collapses. Seismic reflection studies through the WAIS have revealed thick successions of strata with seismic characteristics comparable to upper Tertiary marine sediments. Small samples of glacial diamictons from beneath the ice sheet have been collected via hot-water drilled access holes. These sediments include mixed diatom assemblages of varying ages. Late-Miocene diatoms dominate many samples, probably reflecting marine deposition in West Antarctic basins prior to development of a dominantly glacial phase in West Antarctica. In addition to late-Miocene diatoms, samples from Upstream B (1988/89) contain rare post-Miocene diatoms, many of which imply deposition in the West Antarctic interior during one or more Pleistocene deglaciation periods. Age-diagnostic fossils in glacial sediments beneath ice sheets provide relatively coarse chronostratigraphic control, but they do contain direct evidence of regional deglaciation. Thus, sub-glacial till samples provide the evidence regarding the source of ice sheet variability seen in well-dated proxy records. Combined, these independent data sets can provide a more comprehensive and less speculative interpretation of the history of past glacial minima in currently glaciated polar regions.

A late Pliocene - early Pleistocene, 2.9-2.0 Ma, diatom record from the Antarctic Geological Drilling Program (ANDRILL) MIS drillcore AND-1B is presented. This core, recovered from beneath the Ross Ice Shelf south of Ross Island, comprises multiple diatomaceous-sediment units deposited during interglacial periods with open water over the core site. These represent interglacial phases of orbitally paced climate cycles and are punctuated by glacial advances. Extant diatom assemblages have limited presence in the late Pliocene record, which makes environmental interpretation less straight forward. We employ modern ecological data in combination with late Pliocene to present variation in diatom assemblages across the Southern Ocean oceanic fronts based on DSDP/ODP diatom biostratigraphic data to evaluate paleoenvironmental change for the 2.9-2.0 Ma interval of the AND-1B core. The diatom assemblages from AND-1B record a progressive environmental change through the late Pliocene-early Pleistocene. A relatively warm period with potential SST of up to 4 °C at ca. 2.9 Ma was succeeded by a reduction of warm water species and an increase of taxa associated with more southerly water masses until 2.58 Ma (at isotope stage G1). Younger, early Pleistocene, diatomaceous units are dominated by extinct Rouxia, Thalassiosira species and newly described Fragilariopsis species indicative of cold open water and drift ice. The last recorded cooling step occurs at the top of the interval studied (ca 2.0) Ma indicated by the trace abundance of Fragilariopsis and Actinocyclus species present in modern sea ice assemblages but absent in the late Pliocene-early Pleistocene AND-1B record, even though many of its species had their first occurrences during the Pliocene. The extant sea ice assemblage occurs with an abundance of 2-29% (average 10%) in the late Pliocene-early Pleistocene AND-1B record implying that the modern sea ice and ice shelf polar conditions were not established within the studied interval. The most frequently applied sea ice indicator, Fragilariopsis curta, is consistently present in low to moderate abundance (1-22%) together with Chaetoceros resting spores (2-30%) through the 2.9-2.0 Ma interval. The diatom assemblage shifts indicate a dynamic environment with an overall trend towards colder conditions after ca. 2.6 Ma but does not reach the Holocene configuration.

During the great 1964 earthquake, parts of coastal southern Alaska subsided tectonically as much as 2 m, and this led to burial of high-intertidal organic-rich marshes by low-intertidal and tidal silt. In the tectonically active parts of upper Cook Inlet, the presence of stratigraphic sections containing numerous prehistoric interbedded layers of peat and silt suggests that such stratigraphy resulted when marshes and forests were similarly inundated and buried by intertidal and tidal sediment as a result of great, prehistoric earthquakes. This study tests the feasibility of using buried, radiocarbon-dated, late Holocene peat layers that are exposed in the intertidal zone of upper Cook Inlet to determine earthquake recurrence intervals. Because of problems associated with conventional radiocarbon dating, the complex stratigraphy of the study area, the tectonic setting, and regional changes in sea level, conclusions from the study do not permit precise identification of the timing and recurrence of paleoseismic events. -from Authors

New Zealand offers a unique opportunity to investigate the response of extinct megafaunal ecosystems to major changes in climate and habitat prior to human settlement. Prior to this point (late 13th Century AD) New Zealand contained a diverse avian megafauna dominated by nine species of large flightless ratite moa (Dinornithiformes). We used ancient DNA approaches to generate mitochondrial DNA sequence data from 39 crested moa (Pachyornis australis) and 145 heavy-footed moa (Pachyornis elephantopus) specimens. In combination with radiocarbon dating and dietary isotope analysis we examined the effects of Late Pleistocene and Holocene climate and environmental change on the phylogeography, palaeodemographics, and eventual extinction of Pachyornis. We show that Pachyornis changed altitudinal,...

The Vasto town (Abruzzi, central Italy) raises 143 m a.s.l., on the top of an uplifted Quaternary regressive sequence. The coastal slope is affected by large slope instability (Vasto Landslide) with evidence of present activity, as suggested by several geomorphic features. Well documented historical disruptive events affected the town and the coastal slope in 1816, 1942 and 1956, with deformation locally reaching the near offshore. Field morpho-stratigraphic evidences suggest that sea cliff retreat must have removed considerable volumes of rock before the first activation of the large slope instability. Thus, a morpho-evolutive model of the Vasto Landslide is proposed here, which takes into account the present landforms, the field geological evidences as well as borehole stratigraphy and the combined effect of Quaternary uplift and eustatic oscillations on the coastal slope, since the area started emerging (early Middle Pleistocene) and up to present. Some significant steps were identified, given the tectono-eustatic constraints, and slope stability was analysed with the method of slices (Fellenius) for the different steps. The analysis confirms the kinematic consistency of the first activation of two major roto-translational surfaces in the Middle Pleistocene, after considerable sea cliff retreat. Finite difference stress-strain numerical modelling (FDM) of the Vasto Landslide was then performed in order to output: 1) the landslide mechanism; 2) the style of activity of the landslide; 3) the cumulative deformations occurred during the morpho-evolutive steps. The numerical modelling was calibrated by considering the present landforms as well as the effects recorded during the historical events. The results obtained here confirm that the Vasto Lanslide was first activated in the Middle Pleistocene (~200 ka B.P.), as a consequence of wave cut erosion and progressive emersion of the coastal slope. Moreover, the landslide evolved as a retrogressive, single-styled landslide, divided in two major blocks. In this frame, the historical events are interpreted as local re-activations, due to meteo-climatic agents, of the ancient rupture surfaces affecting the entire slope.

Intraspecific phylogeography has been used widely as a tool to infer population history. However, little attention has been paid to Southeast Asia despite its importance in terms of biodiversity. Here we used the cytochrome oxidase I gene of mitochondrial DNA (mtDNA) for a phylogeographic study of 147 individuals of the black fly Simulium tani from Thailand. The mtDNA revealed high genetic differentiation between the major geographical regions of north, east and central/south Thailand. Mismatch distributions indicate population expansions during the mid-Pleistocene and the late Pleistocene suggesting that current population structure and diversity may be due in part to the species' response to Pleistocene climatic fluctuations. The genealogical structure of the haplotypes, high northern diversity and maximum-likelihood inference of historical migration rates, suggest that the eastern and central/southern populations originated from northern populations in the mid-Pleistocene. Subsequently, the eastern region had had a largely independent history but the central/southern population may be largely the result of recent (c. 100,000 years ago) expansion, either from the north again, or from a relictual population in the central region. Cytological investigation revealed that populations from the south and east have two overlapping fixed chromosomal inversions. Since these populations also share ecological characteristics it suggests that inversions are involved in ecological adaptation. In conclusion both contemporary and historical ecological conditions are playing an important role in determining population genetic structure and diversity. PMID:16262854

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.

The stratigraphy of the Sarkisla area, southeastern Central Anatolian Massif, is characterized by a succession of rock units ranging from late Paleocene to Pliocene in age. The Caldag group mostly consists of deep-water units and forms the base of the Tertiary rocks. However, its relation to the basement rocks is not observed in the area. This group is represented by late Paleocene-Lutetian-age turbiditic pyroclastics and limestones, andesitic lavas and pyroclastics topped with reefal limestones, and turbiditic limestones and pyroclastics alternating with limestone blocks. During Lutetian to early Priabonian time, shallow marine clastics were deposited along the southern margin of the basin, while continental clastics and platform limestones accumulated along the northern margin. Late Priabonian to early Oligocene time is represented by gypsiferous deposits followed by late Oligocene-age fluvial clastics. The gypsiferous deposits conformably overlie the shallow marine formations but rest on the Caldag group unconformably. During early to middle Miocene time, alternating lacustrine limestones, gypsum, and basalts formed on the fluvial clastics; to the north, basalts formed on the platform limestones. The uppermost sequence of the basin, composed of Tortonian-early Pliocene-age fluvial clastics, lacustrine limestones, and fan deposits, unconformably overlies the older formations. The stratigraphy of the study area is similar to the Ulukisla basin, southwestern Central Anatolian Massif. Therefore, this basin can be considered to be the prolongation of the Ulukisla basin offset by the Ecemis fault.

To understand the temporal and spatial variation of eustatic sea-level fluctuations, glacio-hydro-isostacy, tectonics, subsidence, geologic environments and sedimentation patterns for the Quaternary of a passive continental margin, a nearly complete stratigraphic record that is fully integrated with a three dimensional chronostratigraphic framework, and paleoenvironmental information are necessary. The Albemarle Embayment, a Cenozoic regional depositional basin in eastern North Carolina located on the southeast Atlantic coast of the USA, is an ideal setting to unravel these dynamic, interrelated processes.Micropaleontological data, coupled with sedimentologic, chronostratigraphic and seismic data provide the bases for detailed interpretations of paleoenvironmental evolution and paleoclimates in the 90. m thick Quaternary record of the Albemarle Embayment. The data presented here come from a transect of cores drilled through a barrier island complex in the central Albemarle Embayment. This area sits in a ramp-like setting between late Pleistocene incised valleys.The data document the episodic infilling of the Albemarle Embayment throughout the Quaternary as a series of transgressive-regressive (T-R) cycles, characterized by inner shelf, midshelf, and shoreface assemblages, that overlie remnants of fluvial to estuarine valley-fill. Barrier island and marginal marine deposits have a low preservation potential. Inner to mid-shelf deposits of the early Pleistocene are overlain by similar middle Pleistocene shelf sediments in the south of the study area but entirely by inner shelf deposits in the north. Late Pleistocene marine sediments are of inner shelf origin and Holocene deposits are marginal marine in nature. Pleistocene marine sediments are incised, particularly in the northern half of the embayment by lowstand paleovalleys, partly filled by fluvial/floodplain deposits and in some cases, overlain by remnants of transgressive estuarine sediments. The shallowing through time of Quaternary sediments reflects the eastward progradational geometry of the continental shelf.The preservation potential of marginal marine deposits (barrier island, shoreface, backbarrier deposits) is not high, except in topographic lows associated with late Pleistocene paleovalleys and inlets because the current interglacial highstand has not yet reached its highest level. Given the documented increase in rate of relative sea-level rise in this region, shallow marine conditions are likely to return to the central Albemarle Embayment in the near future. ?? 2011 Elsevier B.V.

Akademicheskii Ridge of Lake Baikal represents a 300 m deep underwater rise, which separates the Central Basin (1647 m water depth) and the North Basin (970 m water depth) of 640 km long lake. The large distance to the turbid load of particle-carrying tributaries and coastal areas as well as the absence of slide induced turbidites are responsible for low sedimentation rates. A large number of short cores (approx. 120 cm) was used to study in detail the Holocene-Late Pleistocene transition, using lithological composition, magnetic susceptibility, microfossils, pollen and spores, chemistry, grain size and mineral composition. Holocene sediments show sedimentation rates from 0.015 to 0.25 mm y-1 and are mainly composed of biogenic material with rare admixtures of aeolian and ice-rafted terrigenous particles [1]. The sediments are characterized by abundant microfossils, such as diatoms, spicules of sponges, chrysophyte cysts, pollen and spores. Holocene diatom assemblages are representated by Aulacoseira baicalensis, A. skvortzowii, Cyclotella minuta, C. baicalensis, Synedra acus var.radians, Stephanodiscus meyerii, Crateriportula inconspicuus and Cyclostephanos dubius [2]. Concentrations of Corg.,Ntot.,and Sibiog.indicate clearly higher productivity of the lake during the Holocene [1]. Late Pleistocene sediments are composed of clastic, fine-grained, clayey material, mainly of terrigenous origin. This includes also aeolian particles and rare ice-transported sandy material and rock debris. A peak of the diatom species Stephanodiscus flabellatus, observed within the upper part of clayey sediments, defines the Late Pleistocene-Holocene transition [2]. Very low contents of microfossils (diatoms, spicules of sponges, chrysophyte cysts etc.) within Late Pleistocene deposits indicate lower productivity of Lake Baikal. Glacial melt-water dominated the sediment transport processes within the lake during this time. The main minerals of the sand fraction are quartz, feldspars and mica. The heavy mineral assemblage contains amphiboles, pyroxenes, epidote, sphene, magnetite, garnet and chloritoide. Within the Holocene, contents of chloritoide are low (0.6-1.2 %), but they are distinctly higher within the Late Pleistocene sediments (3.2-14.6 %) [1]. An increase of chloritoide in sediments points towards an intensification of aeolian transport by stronger winds and longer-lasting periods of ice cover during the Late Pleistocene [3]. Results of pollen analyses support these findings. They indicate that mountain slopes of the catchment of Lake Baikal were mostly uncovered by vegetation. A polymineral composition is characteristic for the clay fraction of Late Pleistocene deposits: hydro-mica, kaolinite, smectite and chlorite. This is caused by extensive glaciation of the catchment of the lake during this time [4], generating increased transport of terrigenous material to the lake by glacial melt water [5]. References [1] Vologina, E.G. and Sturm, M. 2009. Types of Holocene deposits and regional pattern of sedimentation in Lake Baikal. Russian Geology and Geophysics 50, 1-6. [2] Bradbury, J.P., Bezrukova, Ye.V., Chernyaeva, G.P. et al. 1994. A synthesis of post-glacial diatom records from Lake Baikal. J. Paleolimnol. 10, 213-252.

Molar teeth of both Tertiary and Quaternary representatives of the family Antilocapridae were examined using mesowear and light stereomicroscopy microwear. Taxa from the Central and Southern Great Plains and the Northern and Southern Great Basin were included in the analyses and results compared to those obtained on the modern pronghorn (Antilocapra americana). Species included spanned from the early Miocene (late Hemingfordian) to the late Pleistocene (Rancholabrean). Results are concordant with well-known trends toward increasing aridity and shifts in vegetational structure in the late Miocene?early Pliocene of North America. Both mesowear and microwear results indicate a shift toward more abrasive diets beginning in the Hemphillian (late Miocene?Pliocene) and then a return to a less abr...

The sedimentary record of the continental shelf off Rio de Janeiro State is related to the opening and evolution of Atlantic Ocean. The combined analysis of high resolution seismic acquired in the early 80's (Geomar cruises) and 2D seismic lines of petroleum industry, coupled with chronostratigraphic data from oil industry's exploratory wells, allowed us to observe two different orders of sequences: of 3-4th order, that represents sedimentary units related of the Milankovitch cycles (100/40/20ky), and of 2nd order (10-100my). High resolution seismic allowed us to outline a first architectural framework for the actual shelf that is composed of stacked seismic units making up the major seismic sequences bounded by angular unconformities. According to the intern and extern configuration of their clinoforms, the seismic sequences were grouped into two distinctive stratigraphic sets, identified as Set I (Pliocene) and Set II (Upper Quaternary). Some architectural components of note include: (1) the characteristic upbuilt-outbuilt geometry of sequences that compose Set I (SqA, SqB and SqC), indicating that deposition has probably been favoured by a combination of prevailing subsidence regime (upbuilt pattern) accompanied by forced regressive deposits (outbuilt pattern); (2) the majority of sequences that make up Set II outbuilts as a composite seaward-thickening progradational wedge formed under dominant forced regression conditions, implying that the generation of accommodation space was less important than during the build-up of Set I. However, these sequences consistently pinch out in a progressively landward direction, suggesting a prevailing and increasing subsidence regime able to induce the progressive seaward tilting of the margin during the middle-late Pleistocene, and the subsequent partial preservation of regressive sequences of about 100-200 m thick at the level of the present-day mid-shelf, that prograded seaward for circa 15-25 km. These architectural elements provide a hint at a prevailing subsidence regime and effective sediment supply into the basin that clearly contrast with the conveyed idea of a sediment-starved and tectonic stable shelf. They naturally raise questions about the nature and origin of sediment supply, since no significant point siliciclastic fluvial source flows directly into the shelf. Stemming from that, we are forced to speculate about: (A) the role of neotectonic movements involving the Serra do Mar coastal mountain ranges to potentially source clastic influx into the basin during the Quaternary, or about the real importance of secondary drainage basins debouching today; and (B) the mechanical nature of a supposed subsidence during the Pliocene and the Quaternary time span (overloading ? sediment compaction ? thermal cooling ?). The interpretation of industrial seismic lines can provide the answers of many of these questions. The next step of this work is to make a stratigraphy model of the sedimentary systems of Santos basin to understand how the ancient creation of accommodation space can influence the recent sedimentary architecture and how is the change in sedimentary influx and the sedimentary records of different orders of cyclicity.

The island of Barbuda, located some 75 km north of Antigua, contains an off-lapping sequence of horizontal carbonates which document a pattern of progressively falling sea level stands punctuated by at least three major intervals of subaerial exposure when sea level was at or below its present level. This sequence can be summarized as follows: (1) Pliocene Highlands Formation with deposition of bank edge, fore-reef deposits 50 to 100 m above present sea level; (2) Bat Hole subaerial phase with karst development; (3) early (.) Pleistocene Beazer Formation with fringing reefs, protected bays and development of sea caves at 10 to 15 m above present sea level; (4) Marl Pits subaerial phase with karst development and soil formation; (5) late (.) Pleistocene Codrington Formation Phase I with fringing and barrier reefs, back-reef lagoons and sea cave development at 5 m above present sea level; (6) late (.) Pleistocene Codrington Formation Phase II with prograding beach ridges and sea level falling from 5 m to below present level; (7) Castle Bay subaerial phase with karst development, caliche and coastal aeolian dunes; and (8) Holocene (post-3000 B.P.) Palmetto Point transgression with development of the present reef, lagoon and southwestern beach ridge complex. The evidence suggests that Burbuda has been relatively stable and has not undergone significant uplift during this period. Shoreline fluctuations appear consistent with glacio-eustatio sea level changes since the Pliocene.

The postcanine tooth crowns of late Early Pleistocene Homo erectus from Sangiran, Java, have been considered to be significantly smaller than those of older H. erectus remains of the same region. In this study, the degree of dental reduction in the former was examined by comparing their postcanine crown size with that of various regional groups of recent H. sapiens. The results show that overall crown size and degree of posterior molar reduction of Javanese H. erectus of the late Early Pleistocene was within the range of variation of recent H. sapiens. The position of this H. erectus group in the general trend of dental reduction in Early to Middle Pleistocene Asian archaic Homo is discussed. Implications for the phylogenetic discontinuity hypothesis between H. erectus and H. sapiens in Australasia are presented. In contrast to their reduced crown size, the Javanese H. erectus remains exhibit robust root systems, presumably a primitive retention. This observation indicates that reduction in crown size preceded reduction of the roots during evolution of Homo, at least in the Sunda region.   

Diatom biostratigraphy for the latest early Miocene to earliest Pliocene of California is updated by new correlations to absolute time, and additional secondary datum levels (first and last occurrences) are identified. As yet, late middle Miocene to latest Miocene (14-6 Ma) diatom datum levels have not been correlated directly with magnetic stratigraphy in the northeast Pacific. Absolute ages are estimated indirectly by correlating northeast Pacific diatom datum levels with tropical Pacific diatom datum levels, which are correlated directly with magnetic stratigraphy. DSDP sections in the northeastern Pacific (Sites 470, 472) and northwestern Pacific (Site 438) contain mixtures of tropical and temperate diatom species. Graphical correlation techniques applied to these sections correlate temperate datum levels to tropical datum levels and, hence, to magnetic stratigraphy. Absolute ages for these datum levels are then estimated using magnetic time scales. W.A. Berggren et al suggested a new correlation of magnetic anomaly 5 (8.92-10.42 Ma) with magnetic polarity Chron 11, rather than with Chron 9. Significant changes in absolute age estimates from late middle Miocene to early late Miocene diatom zones and subzones are as follows: base of Denticulopsis hustedtii-D. lauta zone = 13.8 Ma; base of subzone b = 12.7 Ma; base of subzone c = 11.4 Ma; base of subzone d = 8.9 Ma; base of D. hustedtii zone = 8.4 Ma; top of D. hustedtii zone (base of Thalassiosira antiqua zone) = 7.6 Ma. Graphical correlation techniques have been applied to stratigraphic sections from Newport Beach, Naples coastal bluffs, Lompoc, Monterey, and the type Luisian area near Paso Robles, as well as from DSDP Sites 173, 468, 469, and 470, and have identified 31 secondary diatom datums and 4 silicoflagellate datums that are the most useful for correlations.

In the Lesser Antilles, the Plio-Pleistocene carbonate platforms have developped in a fore-arc setting on the top of a ancient (Oligo ?-Miocene) abandonned arc (Bouysse et al., 1990). These platforms are cut by normal faults and provide index beds or units that are usefull for studying the arc-parallel extension (Feuillet et al., 2001 ; 2002 ;2004). They were considered to be composed of two main units (Garrabé, 1983) : a lower unit, up to 100 m thick, made of Plio-Pleistocene rhodolithic limestones with an interstratified volcanodetritic index bed and an upper unit, 20-30 m thick, made of lower Pleistocene reef corals. This biostratigraphic frame was mainly established from the study of the Simonière drill (Andreieff et al., 1987). Contradictively, Feuillet et al. (2004) suggested that the upper unit should rather be upper Pleistocene in age based on U/Th datings of corals. Léticée et al. (2005) showed that the upper unit has to be divided into two distinct reef units separated by an erosive and aerial surface and that at least two other main erosive surfaces can be recognized within the rhodolitic unit. Here, we conduct an integrated calcareous plankton magnetobiostratigraphy of the carbonate platforms in order to precise the timing of the arc-parallel extension in the Guadeloupe archipelago. This integrated study is also based on Argon dating. The base of the carbonate platforms unconformably rests upon upper Tortonian to upper Messinian (8.44-5.77 Ma) volcanodetritic sediments outcropping in Marie-Galante. Our results show that the lowermost deposits are upper Zanclean to Piacenzian in age (Zones Pl2-Pl3 and NN13/15-NN17, basal part of Chron C2An) in Grande-Terre. However, the base of the series cannot be observed on Grande-Terre to the contrary of Marie-Galante and La Désirade. In La Désirade, the sedimentation started much earlier since the uppermost part of the carbonate platform yielded Zanclean to Piacenzian ages (Zones Pl2-Pl3 and uppermost NN13/15 to NN16). Unfortunately, the lower part has not yielded any biostratigraphic marker, yet. In Grande-Terre, the volcanodetritic index-bed, that is bounded by two erosional surfaces, is Piacenzian in age (Zone Pl5) and falls within the Gauss Subchron (C2An.1n). Overlying deposits are upper Gelasian to Calabrian in age (Pl5-Pt1 Zones) and pyroclastic materials from the lowermost part of these deposits yielded an 40Ar/39Ar age of 1.94 ± 0.06 Ma. The two reefal units that cap the series did not yield any biostratigraphic marker and both exhibit a normal magnetic polarity. From biostratigraphic constraints and magnetostratigraphy of the underlying deposits, we propose to correlate this normal polarity to the Olduvai Subchron (C2n). However, we cannot ensure precisely the age of the last reefal unit as it overlyies an erosional surface (S1 in Léticée et al., 2005). We have also found this erosional surface on Marie-Galante, then suggesting a similar evolution of both islands during Plio-Pleistocene times. We believe that the age of the youngest carbonate platform deposits should be Early Pleistocene (Gelasian) rather than Late pleistocene (Ionian). In La Désirade, we have also evidenced Gelasian deposits (Zones Pl6 and NN18) but 270 m down from the top of the Island where Late Zanclean to Early Piacenzian deposits occur. This indicates that La Désirade experienced a major uplift phase during the Late Piacenzian prior to the uplift that occurred during the Calabrian in Grande-Terre and Marie-Galante. The three main islands of the Guadeloupe archipelago have thus experienced different tectonic histories and the present-day morphology of these islands does not solely result from a single, Late Pleistocene uplift/tilt event.

The middle Pleistocene fossil mammal assemblage from Lainyamok in the southern Kenya rift has previously been considered the oldest (330-392ka) African mammal community consisting entirely of extant species, with the dominant bovid tentatively attributed to the southern African blesbok (Damaliscus cf. dorcas). We show that the blesbok-like fossils from Lainyamok belong to an extinct species, described here as Damaliscus hypsodon sp. nov. The D. hypsodon hypodigm includes the previously unnamed small alcelaphine material known from late Pleistocene sites elsewhere in Kenya and Tanzania. Its dental anatomy, together with an ecomorphological analysis of its postcrania, indicates that D. hypsodon grazed in open and arid grassland environments. Although Lainyamok is no longer represented entire...

Pleistocene faunas from south China are difficult to subdivide based on the long temporal ranges of many taxa and a reduced number of genera in comparison to faunas from temperate north China. In south China, the Ailuropoda?Stegodon fauna is a very general one and includes a relatively stable suite of genera that apparently persisted for long periods of time. These attributes have made constraining its time range difficult. Application of electron spin resonance (ESR) dating of tooth enamel constrains the ages well where uranium uptake was minor. Where uranium uptake into teeth was significant, an approach combining ESR and 230Th/234U isotopic analysis also yields excellent ages. Previous estimates of early, middle and late Pleistocene time ranges previously determined by biostratigraphic ...

Although the occurrence of Pleistocene mammals is abundant in many localities of Minas Gerais State (e.g., Lagoa Santa, Janaúba, Bambuí, Cordisburgo, Patos de Minas, Araxá), there are no references at present of Quaternary megafauna in Uberaba, Triângulo Mineiro, southeastern Brazil. This region is traditionally recognized for its taxonomically diverse fauna of the Late Cretaceous Bauru Group. In 2006, fossil material attributed to giant ground sloth Eremotherium laurillardi (Xenarthra, Megatheriidae), a typical taxon of the Brazilian Pleistocene, was discovered in the Uberaba City (Minas Gerais State). The specimen (CPP 1122) which is here described consists of several cranial and postcranial bones of a single individual. The material was confined to a small alluvial deposit, yielding in the Córrego da Saudade stream, which due its restricted area distribution it is not represented in geological maps.

Although the occurrence of Pleistocene mammals is abundant in many localities of Minas Gerais State (e.g., Lagoa Santa, Janauba, Bambui, Cordisburgo, Patos de Minas, Araxa), there are no references at present of Quaternary megafauna in Uberaba, Triangulo Mineiro, southeastern Brazil. This region is traditionally recognized for its taxonomically diverse fauna of the Late Cretaceous Bauru Group. In 2006, fossil material attributed to giant ground sloth Eremotherium laurillardi (Xenarthra, Megatheriidae), a typical taxon of the Brazilian Pleistocene, was discovered in the Uberaba City (Minas Gerais State). The specimen (CPP 1122) which is here described consists of several cranial and postcranial bones of a single individual. The material was confined to a small alluvial deposit, yielding in ...

At the close of the Pleistocene, fire regimes in North America changed significantly in response to climate change, megafaunal extinctions, anthropogenic burning and, possibly, even an extraterrestrial impact. On California's Channel Islands, researchers have long debated the nature of late Pleistocene ''fire areas,'' discrete red zones in sedimentary deposits, interpreted by some as prehistoric mammoth-roasting pits created by humans. Further research found no evidence that these red zones were cultural in origin, and two hypotheses were advanced to explain their origin: natural fires and groundwater processes. Radiocarbon dating, X-ray diffraction analysis, and identification of charcoal from six red zones on Santa Rosa Island suggest that the studied features date between ~27,500 and 11...

The chronostratigraphical subdivision of the Pliocene and Early Pleistocene as applied in terrestrial deposits of Central and NW-Europe largely relies on the pollen analytical investigations. This subdivision is almost entirely based on the interpretation of quantitative changes of the vegetational cover as recorded by the pollen content of fluvial deposits in the Lower Rhine Embayment. The Early and Middle Pliocene stages are originally defined in the type areas near Susteren and Brunssum along the southern border of the roer valley graben (RVG). Late Pliocene and Early Pleistocene stages have been defined in the Venlo-Tegelen area on the Peel Block, just north of the RVG.A critical review of existing data has been carried out considering lithostratigraphical data, provenance studies and ...

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 from the LYDB at Murray Springs and two other well-stratified Clovis sites. The main magnetic fraction at Murray Springs is maghemite. Magnetic microspherules have terrestrial origins but also occur as cosmic dust particles. We failed to find iridium or radiation anomalies. The evidence for massive biomass burning at Murray Springs is addressed and found to be lacking. We could not substantiate some of the claims by Firestone and others, but our findings do not preclude a terminal Pleistocene cosmic event. PMID:20160115

Many caves in Sierra de Atapuerca contain archaeological and anthropological remains from the Early Pleistocene until the Holocene. The fi rst half of the Late Pleistocene (MIS 4 and 3) has only been detected in open air deposits discovered on the basis of total cover surface surveys. Excavation at one of them, Hundidero, began in 2004. The Middle Paleolithic tool record spans the period between 70 ka and 56 ka. The technological and typological features of Hundidero, along with records from 30 other contemporary open air sites at Atapuerca, suggest repeated visits by Neanderthals who shared the same cultural tradition, characterized by expedient tool production, a diversity of exploitation techniques, a microlithic tendency, a search for dorsal faces, and the reuse of previous tools. Thes...

Formation of crustal magma chambers in Iceland may be facilitated by the occurrence of stress barriers that lead to formation of thick sills. Such sills absorb the magma of all dikes that enter them and may evolve into magma chambers. Ideal sites for stress barriers, and hence for magma chambers, are rock formations where individual layers have different elastic properties. The rocks formed during the Pleistocene have notably different elastic properties, and when buried in the volcanic zones, they form more promising sites for magma chambers than the Tertiary rocks. This may explain why the number of magma chambers, indicated by the number of corresponding central volcanoes, during the late Pleistocene (i.e., during the past 0.7 m.y.) appears to be proportionally greater than the number of chambers (i.e., central volcanoes) active during Tertiary time.

Predator/prey relationships in Mediterranean Europe during the Early Pleistocene are analysed at the local and regional scales and compared to patterns observed in recent fauna from four regions worldwide (East Africa, South Africa, Southeast Asia and North America). Three subregions (South Eastern, Central and South Western Mediterranean) and three time periods (middle Villafranchian, late Villafranchian and Galerian) are considered. Our approach focuses on large primary consumers and their potential predators; both are defined as mammals weighing over 10kg. Early Pleistocene food webs are characterised by a unique body size distribution of primary consumers and an extremely rich carnivore guild. These characteristics likely affected ecosystem function in a way not observed in recent comm...

Paleosols and Pleistocene loess-paleosol sequences preserve important information on landscape stability and soil formation, paleoclimate, and paleoenvironment. The nature of clay mineral assemblages (mineral composition of the clay fraction, conditions and paleoclimate. Interpretation of the time sequence of climate/environmental change however requires careful determination of pedogenic mineral phases from phases altered by later diagenesis. Red clays and paleosols in Hungary overlain by loess-paleosol sequences were studied. Elemental oxide analyses of red clays and paleosols were determined by X-ray florescence (XRF), and X-ray powder diffraction (XRD) was used for mineral identification and oriented specimens for clay mineral analyses. In this study, we aim to determine the temporal changes of clay minerals due to chemical weathering and time. Upper Pliocene red kaolinitic clay contains typically disordered kaolinite, mixed-layer smectite/kaolinite, smectite and little gibbsite. It could be formed in the local subaerial weathering crust in warm, humid, subtropical or monsoon climate (Köppen climate classification Cfa) which is a climate zone characterized by hot, humid summers and generally mild to cool winters. Kaolinite together with gibbsite in this type of the studied red clays can be inherited from pre-Pliocene lateritic soils, potentially formed during the Eocene-Middle Miocene. A temperate wet condition can be suggested for the Late Pliocene. Lower Pleistocene red (or "reddish") clay contains relatively fresh material (illite, chlorite), the weathering products are predominantly smectite and goethite formed under warm-summer Mediterranean climate (Csb). This subtype of the Mediterranean climate experiences warm (but not hot) and dry summers, winters are rainy and can be mild to chilly. Mid-Pleistocene paleosols of the loess-paleosol sequences and red clays contain similar material as the underlying red clays belonging to the Lower Pleistocene unit. The slightly but significantly lesser degree of weathering (more illite and chlorite, less smectite) indicates cooling of the climate. Based on the results, the climatic conditions were similar to the previously discussed. It was also Csb, but cooler with less precipitation. Results from geochemical climofunctions applied to Upper Pliocene-Lower Pleistocene red clays and paleosols located in the Carpathian Basin, and clay mineralogy, indicate that the paleoclimate was considerably more humid and warmer during the Late Pliocene-Early Pleistocene, in comparison to modern values. This contribution was made possible through financial support by 'Developing Competitiveness of Universities in the South Transdanubian Region (SROP-4.2.1.B-10/2/KONV-2010-0002)' and Austrian Agency for International Education & Research, financed by the Scholarship Foundation of the Republic of Austria (OeAD). It was additionally supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences.

The survey on the nuclear raw mineral (uranium) deposits had been carried out for a long time from early 1960`s to late 1980`s by the Geological and Mineral Institute of Energy and Resources. Unpublished data of the uranium ore deposits of Kumsan area is published on this paper. Geology on the Ogcheon System have been controversial by many geologists, therefore we have reviewed on the geology and stratigraphy. Particularly, we have interpreted the host root rock on the magnetite bearing banded gneiss, which is named so called Kyemeongsan Formation. (author). 5 maps.

The survey on the nuclear raw mineral (uranium) deposits had been carried out for a long time from early 1960`s to late 1980`s by the Geological and Mineral Institute of Energy and Resources. Unpublished data of the uranium ore deposit of Goesan Deokpyeongri A area is published on this paper. Geology on the Ogcheon System have been controversial by many geologists, therefore we have reviewed on the geology and stratigraphy. Particularly, we have interpreted the host root rock on the magnetite bearing banded gneiss, which is named so called Kyemeongsan Formation. (author). 12 maps.

The survey on the nuclear raw mineral (uranium) deposits had been carried out for a long time from early 1960`s to late 1980`s by the Geological and Mineral Institute of Energy and Resources. Unpublished data of the uranium ore deposit of Goesan Deokpyeongri B area is published on this paper. Geology on the Ogcheon System have been controversial by many geologists, therefore we have reviewed on the geology and stratigraphy. Particularly, we have interpreted the host root rock on the magnetite bearing banded gneiss, which is named so called Kyemeongsan Formation. (author). 8 maps.

The survey on the nuclear raw mineral (uranium) deposits had been carried out for a long time from early 1960`s to late 1980`s by the Geological and Mineral Institute of Energy and Resources. Unpublished data of the uranium ore deposit of Goesan Deokpyeongri A area is published on this paper. Geology on the Ogcheon System have been controversial by many geologists, therefore we have reviewed on the geology and stratigraphy. Particularly, we have interpreted the host root rock on the magnetite bearing banded gneiss, which is named so called Kyemeongsan Formation. (author). 4 maps.

Late Quaternary sedimentation patterns on the Var deep-sea fan are known from high-resolution seismic boomer profiles (vertical resolution < 1 m), piston cores, SAR side-scan sonargraphs, and submersible dives. Foram biostratigraphy and radiocarbon dating provide chronologic control that is seismically correlated across the fan. Regional erosional events correspond to the isotopic state 2 and 6 glacial maxima. A widespread surface sand layer was deposited from the 1979 turbidity current, which broke two submarine cables. Numerical modeling constrains its character. A small slide on the upper prodelta developed into an accelerating turbidity current, which eroded sand from the Var canyon. The current was 30 m thick in the upper valley, expanding downflow to >120 m, where it spilled over the eastern Var sedimentary ridge at a velocity of 2.5 ms[sup [minus]1]. Other Holocene turbidity currents (with a 103-yr recurrence interval) were muddier and thicker, but also deposited sand on middle fan-valley levees and are inferred to have had a similar slide-related origin. Late Pleistocene turbidity currents deposited on the high Var sedimentary ridge. The presence of sediment waves and the cross-flow slope inferred from levee asymmetry indicate that some flow were hundreds of meters thick, with velocities of 0.35 ms[sup [minus]1]. Estimated times for deposition of thick levee mud beds are many days or weeks. Late Pleistocene flows therefore are interpreted to result from hyperpycnal flow of glacial outwash in the Var River. Variation in late Pleistocene-Holocene turbidite sedimentation thus is controlled more by changes in sediment supply than by sea level.

The primary petroleum system of northeast Sakhalin Island and adjacent shelfal areas is comprised of a system of Late Miocene to Quaternary faulted transpressional anticlines that trap oil and gas in Early Miocene to Pliocene deltaic reservoirs sourced from Late Oligocene to Early Miocene diatomaceous shales. Existing production has been limited to onshore anticlines, and offshore structural trends remain undeveloped, despite several discoveries. The regional tectonic evolution of Sakhalin Island can be divided into five major phases: (1) Late Cretaceous to Early Eocene subduction, (2) Middle-Eocene collision and uplift, (3) Late Eocene to Early Oligocene oblique rifting, (4) Late Oligocene to Middle Miocene thermal subsidence, and (5) Late Miocene to Quaternary transpression and inversion. Oil-prone source rocks were deposited during rapid post-rift thermal subsidence of transtensional rift basins and adjacent highs, which provided an ideal sediment-starved setting for source rock accumulation. Reservoir facies were supplied by prograding post-rift Miocene deltaics of the paleo-Amur river, which built a shelf across the thermally subsiding basin and intrabasin highs. Traps were formed when the basin was later inverted during Late Miocene to Pleistocene transpression, which reactivated both Paleogene normal faults and structural trends of the Mesozoic accretionary prism to create a broad zone of distributed shear. Strike-slip structural styles are evidenced by linear, en echelon alignments of doubly-plunging anticlines characterized by numerous small-displacement, transverse normal faults. Strike slip on individual structures is relatively small, however, based on a lack of thorough going faults. Strike-slip structures on Sakhalin Island are considered active, in light of the earthquake of May 27, 1995 (M=7.6) and uplift of Pleistocene marine terraces.

A late Pliocene - early Pleistocene, 2.9-2.0Ma, diatom record from the Antarctic Geological Drilling Program (ANDRILL) MIS drillcore AND-1B is presented. This core, recovered from beneath the Ross Ice Shelf south of Ross Island, comprises multiple diatomaceous-sediment units deposited during interglacial periods with open water over the core site. These represent interglacial phases of orbitally paced climate cycles and are punctuated by glacial advances. Extant diatom assemblages have limited presence in the late Pliocene record, which makes environmental interpretation less straight forward. We employ modern ecological data in combination with late Pliocene to present variation in diatom assemblages across the Southern Ocean oceanic fronts based on DSDP/ODP diatom biostratigraphic data t...

Abstract in spanish Se caracterizaron el medio físico del ambiente, la fisiografía, el sistema geomorfológico de la región, las características hidrológicas y el origen de la cubeta lagunar. La geología superficial está definida por diez unidades estratigráficas (siete litoestratigráficas y tres pedoestratigráficas). La más antigua es la Formación Ensenada del Pleistoceno medio, que constituye el sustrato regional, donde se excavó la cubeta lagunar. Encima se dispone la Formaci (more) ón Buenos Aires del Pleistoceno tardío, en cuya parte cuspidal se sitúa un Geosuelo Sin Nombre. Las siguientes cuatro unidades corresponden a depósitos eólicos de dunas de arcilla y loéssicos de la Formación La Postrera I, II, III y IV, de edades dispares, que abarcan desde el Pleistoceno tardío al Holoceno tardío-tardío. La Formación La Postrera II y III poseen los Geosuelos Puesto Callejón Viejo y Puesto Berrondo respectivamente. En las playas afloran depósitos aluviales, que incrementan su espesor en el lecho lagunar. En los sedimentos colmatantes se reconocieron seis depósitos, cinco representan a ambientes acuáticos: Formación Luján, Miembros La Chumbiada, Lobos y Río Salado, del Pleistoceno tardío al Holoceno temprano a medio; formación subaluvial del Holoceno tardío y la actual formación aluvial. El sexto es un depósito eólico de duna de arcilla intracuencal del Pleistoceno tardío. El conjunto de los depósitos suprayacentes a la Formación Ensenada supera los 64 ka, representados por cinco episodios de clima seco que abarcan desde el loess Bonaerense hasta la pequeña edad de hielo (IS4, IS2, D3-L3, D2-L2, D1-L1) y cinco húmedos (IS3, S3, IS1, S1 y el actual). Abstract in english The regional physical environment was characterized, describing the physiographic and geomorphic features, the hydrologic regime and the origin of the shallow lake basin. The surficial geology is defined by ten stratigraphic units (seven lithostratigraphic units and three geosols); the oldest one, Ensenada Formation of Middle Pleistocene, makes up the regional substrate, in which the lake basin was excavated. It is overlain by the loess of the Buenos Aires Formation of La (more) te Pleistocene, which is topped by a geosol. The four overlying units are constituted by aeolian deposits (clay dunes and loessic sediments) and two paleosols, ascribed to La Postrera I, II, III and IV Formation from Late Pleistocene to Upper Late Holocene age and the Puesto Callejón Viejo and Puesto Berrondo Geosols. In the lakes infilling sediments, six stratigraphic units were recognized. Five of them are aquatic deposits of decreasing age: Luján Formation, La Chumbiada, Lobos and Río Salado Members from Late Pleistocene to Early to Middle Holocene age; suballuvial formation of Late Holocene and the recent alluvial formation, The sixth unit is a Late Pleistocene intrabasinal clay dune deposit. The sequence of geologic events is registred in the infilling sediments and those of the lake surroundings, which encompass a span much more than 64 ky, represented by five dry climate episodes, from the Buenos Aires Formation loess of Late Pleistocene to La Postrera IV Formation loess, assigned to the little ice age, i.e: IS4, IS2, D3-L3, D2-L2, D1-L1 and five humid, i.e: IS3, S3, IS1, S1 and the present alluvial sediments.

The stratigraphy of the upper 4 m (13 ft) of the western Vermilion Bay area is that of a freshwater swamp (> 35% organic matter and abundant cypress wood fragments). Due to marine inundation, the present surface is covered with a saline marsh. The swamp deposit at 1 m (3 ft) depth possibly correlates with a marsh deposit at the same depth in eastern Vermilion Bay, where three depositional cycles, each containing blanket peats, can be recognized in the upper 9.5 m (31 ft) of the subsurface. The Barataria interdistributary basin displays a great horizontal and vertical organic matter variability. Characteristically, the peats average 90% moisture, 80% organic matter (20% ash), and a bulk density of 0.12 g/cm/sup 3/, the latter two numbers based on dry weight. The frequency distribution of organic matter percentage ranges, for all sediments, shows that in eastern Vermilion Bay 15% of the material is peat; by comparison, in Barataria basin, 5% of all material is peat. Preliminary results from mineralogical and elemental analyses of fresh and brackish peats indicate the presence of clay minerals, quartz, pyrite, gypsum, siliceous spicules, and smaller amounts of the trace mineral rutile. Minerals appear to vary with the type of peat. Elemental inorganic compositions also vary with depositional setting and post-depositional salt-water encroachment. Peat deposits in the deltaic plain show a great variability in stratigraphy and characteristics due to four conditions: (1) difference in depositional setting; (2) depth to the Pleistocene; (3) intermittent interruption of marsh growth by influx of detrital clastics; (4) marine inundation of freshwater peats.

The global Late Pliocene/Early Pleistocene cooling (~3.0-2.0 million years ago - Ma) concurred with extremely high diatom and biogenic opal production in most of the major coastal upwelling regions. This phenomenon was particularly pronounced in the Benguela upwelling system (BUS), off Namibia, where it is known as the Matuyama Diatom Maximum (MDM). Our study focuses on a new diatom silicon isotope (?30Si) record covering the MDM in the BUS. Unexpectedly, the variations in ?30Si signal follow biogenic opal content, whereby the highest ?30Si values correspond to the highest biogenic opal content. We interpret the higher ?30Si values during the MDM as a result of a stronger degree of silicate utilisation in the surface waters caused by high productivity of mat-forming diatom species. This was most likely promoted by weak upwelling intensity dominating the BUS during the Late Pliocene/Early Pleistocene cooling combined with a large silicate supply derived from a strong Southern Ocean nutrient leakage responding to the expansion of Antarctic ice cover and the resulting stratification of the polar ocean 3.0-2.7 Ma ago. A similar scenario is hypothesized for other major coastal upwelling systems (e.g. off California) during this time interval, suggesting that the efficiency of the biological carbon pump was probably sufficiently enhanced in these regions during the MDM to have significantly increased the transport of atmospheric CO2 to the deep ocean. In addition, the coeval extension of the area of surface water stratification in both the Southern Ocean and the North Pacific, which decreased CO2 release to the atmosphere, led to further enhanced atmospheric CO2 drawn-down and thus contributed significantly to Late Pliocene/Early Pleistocene cooling.

A regional sequence-stratigraphic analysis was recently completed for the Tertiary slope sediments in Green Canyon, Ewing Bank, and Mississippi Canyon to provide a chronostratigraphic framework for basin reconstructions and predict lithofacies distributions of reservoir and seal rocks. Sixteen third-order sequences of lowstand deep-water deposits were interpreted for the middle Miocene-Pleistocene section. Thirty regional lithofacies maps were made of predominantly lowstand deposits showing the distribution of shale and sand-prone sediments, slumping, channel levee systems, and fan lobes based on distinctive seismic reflection and well log patterns. These maps were combined with isochrons of selected sequences to identify depositional fairways, depocenters, and paleosalt positions that constantly changed through time. Depositional trends were principally north to south but were also observed to be east-west as salt modified the gradient on the gently dipping slope. In some cases, the structural and stratigraphic trends could be projected under allochthonous tabular salt. Miocene channel and fan lobe sands were found concentrated on the middle-lower paleoslope across the study area. The sedimentation rate doubled (0.7 m/1000 yr) in the early-middle Pliocene, which caused large-scale salt movements and trapped sand-prone turbidites along the upper-middle slope. A four-fold decrease in sediment influx during the late Pliocene-early Pleistocene produced a stacked condensed section of four sequences over the eastern Louisiana slope. A return to rapid sedimentation (up to 2.1 m/1000 yr.) during the Pleistocene reactivated salt movements and depocenters in the Green Canyon, Ewing Bank, and Mississippi Trough areas.

Abstract in spanish El estudio de las características geomorfológicas, de la composición de las series detríticas y de la estructura, permiten precisar las características de la evolución morfoestructural plio-pleistocena del piedemonte occidental de las sierras Chica y de Pajarillo - Copacabana. Su evolución se remonta al Mesozoico tardío y Cenozoico como respuestas a diferentes eventos deformativos. El desarrollo morfosedimentario puede ser dividido en cuatro períodos de agradaci? (more) ?n pedemontana durante el Plio-Pleistoceno y en dos períodos de agradación fluvio-eólico acaecidos durante el Holoceno. Los abanicos aluviales fueron controlados por dos sistemas de fallas: uno de ellos de rumbo longitudinal N y NNO y otro oblicuo de rumbo NO. Otro sistema de rumbo E-O se desarrolló durante los períodos Plioceno y Pleistoceno. Abstract in english The study of the geomorphology, the composition of the detrital series, and the structure, permitted to specify the characteristics of the Plio-Pleistocene morfoestructural evolution of the western piedmont of Sierra Chica and Pajarillo-Copacabana. Its evolution goes back to Late Mesozoic and Cenozoic times and results of diverse deformational events. As many as four Quaternary periods of piedmont fluvial aggradations (Plio-Pleistocene) and two Holocene periods of fluvio- (more) aeolian aggradations are identified. The alluvial fans were controlled by two main fault sets; one of them longitudinal N and NNW trending, and the other oblique with a NW trend. Another E-W fault system took place during the Pliocene and Pleistocene periods.

Mt. Melbourne (2,732 m a.s.l.) is a large quiescent stratovolcano located in Northern Victoria Land (Antarctica) and is one of a handful of volcanoes on the Antarctic plate with the potential for large-scale explosive eruptions. During the XVIII Italian Expedition in 2002-2003, the Mt. Melbourne volcanic succession was studied in terms of stratigraphy and sampled for 40Ar/39Ar age determinations and geochemistry. The early, Lower Pleistocene, volcanism was largely alkali basaltic to hawaiitic in composition and monogenetic in style, producing tens of small scoria cones and lava flows scattered over a wide area across the Transantarctic Mountains (Random Hills Period). During the Middle Pleistocene, volcanic activity focused to the area of the Mt. Melbourne stratovolcano, where several monogenetic centres show the transition from early sub-glacial/subaqueous conditions to emergent subaerial conditions (Shield Nunatak Period). The oldest exposed deposit associated with the early activity of the Mt. Melbourne stratovolcano (Mt. Melbourne Period) is a trachytic subaerial ignimbrite dated at 123.6 ± 6.0 ka, which reflects the establishment of a crustal magma chamber. Above the ignimbrite a succession of alkali basaltic, hawaiitic, and subordinate benmoreitic lavas and scoria cones is exposed, dated at 90.7 ± 19.0 ka. The Holocene deposits are exposed at the top of Mt. Melbourne, where the crater rim is composed of trachytic to rhyolitic pumice fall deposits, which are also extensively dispersed around the volcano, likely originated from Plinian-scale eruptions. The most recent explosive deposit proved difficult to date accurately because very low quantities of radiogenic 40Ar were released, resulting in imprecise plateau ages of 50 ± 70 and 35 ± 22 ka.

The Vienna Basin strike-slip fault is a continent scale active fault extending over a distance of some 300 km from the Eastern Alps through the Vienna Basin into the Western Carpathians. Sinistral movement causes the formation of several tight Pleistocene strike-slip basins within the older Miocene Vienna Basin. These sub-basins not only have a high relevance for groundwater exploitation but their fault activities depict serious seismic hazards. Basins are filled with fluvial sediments from the Danube and, closer to the Alpine front, with thick alluvial fan deposits. However, knowledge on the stratigraphy and tectonics is sparse and rather limited to the Miocene part of the Vienna Basin as it hosts giant hydrocarbon fields. This study tackles two major questions: (i) What is the effect of Quaternary climatic oscillations and subsidence on the sequence development of the alluvial fans and (ii) what is the deformation style of these basins? To answer (i) we present a series of new OSL ages and biotic data from both, surface and cores, to better constrain the timing of fan activity, fan abandonment but also to constrain the onset of Pleistocene basin formation. For (ii) we utilize information from unparalleled geophysical and geological data. Specifically we utilize industrial Bouguer gravity's derivatives to highlight shallow structures and to compensate for the lag of fault trace information. The integration of geological and geophysical data highlights textbook-like models of strike-slip basins, with typical features like Riedel shears with intervening relay ramps, en-echelon sidewall faults and a cross-basin fault zone delimiting opposite depocenters. The infill reflects a distinct cyclicity with thick sequences of coarse sediments deposited during colder periods and thin sequences of paleosol and flood sediments deposited during warmer periods. Ages indicate main activity around the short peak glacial periods and basin formation starting c. 300 ka ago. The distinct sequence development and the strong contrast to the underlying marine deposits is a very suitable setting to apply geophysical methods constraining basins' deformation style.

Ocean Drilling Program (ODP) Site 982 provided a key sediment section at Rockall Plateau for reconstructing northeast Atlantic paleoceanography and monitoring benthic ?18O stratigraphy over the Late Pliocene to Quaternary onset of major Northern Hemisphere Glaciation. A renewed hole-specific inspection of magnetostratigraphic events and the addition of epibenthic ?18O records for short Pliocene sections in holes 982A, B, and C, crossing core breaks in the ?18O record published for Hole 982B, now imply a major revision of composite core depths. After tuning to the orbitally tuned reference record LR04 the new composite ?18O record results in a hiatus, where the Kaena magnetic event might been lost, and in a significant age reduction for all proxy records by 130 to 20 ka over the time span 3.2-2.7 million yr ago (Ma). Our study demonstrates the significance of reliable composite-depth scales and ?18O stratigraphies in ODP sediment records for ocean-wide correlations in paleoceanography and makes Late Pliocene trends found at Site 982 much better comparable to those published from elsewhere in the North Atlantic.

Quaternary alluvial record at the Thar desert margin has been examined using the exposed succession along Mahudi, Sabarmati river, Western India. Different alluvial facies, their associations and granulometry have been studied for palaeoenvironmental reconstruction. Clay mineral indices smectite/chlorite and smectite/illite of the alluvial palaeosols have been used as proxy indicators of climate change. These indicate wet phases during the OIS 5 and OIS 1. The overall stratigraphic development is discussed in the framework of fluvial response to climate change during the Late Pleistocene.

Abstract Uplifted during the 1964 Alaskan earthquake, extensive intertidal flats around Middleton Island expose 1300 m of late Cenozoic (Early Pleistocene) Yakataga Formation glaciomarine sediments. These outcrops provide a unique window into outer shelf and upper slope strata that are otherwise buried within the south-east Alaska continental shelf prism. The rocks consist of five principal facies in descending order of thickness: (i) extensive pebbly mudstone diamictite containing sparse marine fossils; (ii) proglacial submarine channel conglomerates; (iii) burrowed mudstones with discrete dropstone layers; (iv) boulder pavements whose upper surfaces are truncated, faceted and striated by ice; and (v) carbonates rich in molluscs, bryozoans and brachiopods. The carbonates are decimetre sca...

Two biogeographical units are generally recognized in the present shelf area of Argentina: the Magellanian and Argentinian Provinces. The two provinces differ in their fossil record. The evolution of these provinces has been characterized by migrations, extinctions, pseudoextinctions and, perhaps, even speciation events. Marine vertebrate assemblages with some similarities to the Argentinian fauna were already present in the Miocene, whereas no associations similar to those of the Magellanian fauna have been found in South America before the Pleistocene. Two successive major marine transgressions flooded northern Patagonia during the Miocene: the -Patagoniense- (Early Miocene) and the -Entrerriense- (Middle to Late Miocene). We analyse three rich fossil assemblages that were formed during ...

Biogeographic barriers, some transitory in duration, are likely to have been important contributing factors to modern marine biodiversity in the Indo-Pacific region. One such barrier was the Torres Strait land bridge between continental Australia and New Guinea that persisted through much of the late Pleistocene and separated Indian and Pacific Ocean taxa. Here, we examine the patterns of mitochondrial DNA diversity for marine animals with present-day distributions spanning the Torres Strait. Specifically, we investigate whether there are concordant signatures across species, consistent with either vicariance or recent colonization from either ocean basin. We survey four species of reef fishes (Apogon doederleini, Pomacentrus coelestis, Dascyllus trimaculatus, and Acanthurus triostegus) fo...

Crocodylian material from late Pleistocene localities around Antsirabe, Madagascar, stored in the collection of the Museum fur 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 Madag...

Calcium-41 bas been suggested as a new tool for radiometric dating in the range of 10/sup 5/ to 10/sup 6/ years. The concentration of cosmogenic calcium-41 in natural samples of terrestrial origin has now been determined by high-sensitivity accelerator mass spectrometry after pre-enrichment in calcium-41 with an isotope separator. Ratios of calcium-41 to total calcium between 2 x 10/sup -14/ and 3 x 10/sup -15/ were measured for samples of contemporary bovine bone and from limestone deposits. Some prospects for the use of calcium-41 for dating Middle and Late Pleistocene bone and for other geophysical applications are discussed.

Abstract Geochemical (element analysis, molecular analysis of organic compounds), physical, palynological, mineralogical and sedimentary facies analysis were performed to characterise the sedimentary record in Fuentillejo maar lake in the Central Spanish Volcanic Field of Campo de Calatrava, in order to reconstruct the palaeoenvironmental and palaeoclimatic processes which controlled vegetation patterns and deposition of different sedimentary facies. The upper 20 m of core FUENT 1 show variations in clastic input, water chemistry, vegetation and organic fraction sources in the lake throughout the Late Pleistocene and Holocene. The temporal framework provided by 14C accelerator mass spectrometry dating allows assigning the sequence to the last 50 cal. ka BP. Arid phases identified in the FU...

A small Holocene fan is forming where Queen Inlet, a hanging valley, enters West Arm fjord, Glacier Bay, Alaska. Queen fan formed in the last 80 years following retreat of the Little Ice Age glacier that filled Glacier Bay about 200 yr BP. It was built mainly by a turbidite system originating from Carroll Glacier delta, as the delta formed in the early 1900s at the head of Queen Inlet. The Late Holocene Queen fan is comparable to large Pleistocene fans that formed in the Gulf of Alaska and differs from trough-mouth fans formed by cooler climate glacier systems.

A Late Pleistocene molluscan fauna sampled at Ban Praksa, near the Chao Phraya River mouth (Lower Central Plain of Bangkok, Thailand) is herein analyzed and paleoecologically characterized, revealing a shallow infralittoral, coarse/hard-bottomed environment. The comparison of the Ban Praksa association with several coeval ones recovered from Phra Pradaeng Formation seems to be evidence of a 10,000 year hiatus between two separate groups of marine faunas, possibly belonging to different interstadial transgressive peaks that occurred during the long-term sea-level regression following the Last Interglacial.

Ongoing climate change is assumed to be exceptional because of its unprecedented velocity. However, new geophysical research suggests that dramatic climatic changes during the Late Pleistocene occurred extremely rapid, over just a few years. These abrupt climatic changes may have been even faster than contemporary ones, but relatively few continent-wide extinctions of species have been documented for these periods. This raises questions about the ability of extant species to adapt to ongoing climate change. We propose that the advances in geophysical research challenge current views about species' ability to cope with climate change, and that lessons must be learned for modelling future impacts of climate change on species.

The distributions of sediment grain types and microfacies in two outcrop sections in the central part of the Zagros Fold and Thrust Belt, Iran, are used to interpret changes in salinity during Late Oligocene (Chattian) to Early Miocene (Burdigalian) deposition of the Asmari Formation. Conditions of hypersalinity are interpreted from analogy with the modern salinity gradient in Shark Bay, Western Australia, and the time scale is derived from foraminiferal biozonation and Sr-isotope stratigraphy. The study demonstrates that frequent changes in sedimentary facies and salinity conditions took place in the central Zagros basin during the late Chattian, Aquitanian, and Burdigalian. Five main findings of the study are as follows. (1) A significant shallowing from the outer neritic zone (100?m to ...

Sequence stratigraphy, lithostratigraphy and biostratigraphy of the Late Carboniferous/Permian succession of the eastern border of the Parana Basin are organized in the form of a detailed chart in order to provide a useful and updated synthesis of that stratigraphic interval. The traditional lithostratigraphic subdivision is shown together with a third-order stratigraphic framework and a complete biostratigraphic scheme based upon palynomorphs, plants and invertebrate macrofossils. Based on the regional occurrence of features that indicate base level fall and formation of a sequence boundary (e.g., marine to fluvial facies shift, pebbly lags, bonebeds) seven LPTS's (=Late Paleozoic Third-Order Sequences) were recognized and are shown in the stratigraphic chart, enclosed as an color-printed...

A Permo-Triassic volcanic arc system, the Sukhothai Arc, is recognised between the Indochina and Sibumasu continental blocks. The Chanthaburi terrane is here interpreted as a fault-detached, highly disrupted southern segment of the Sukhothai Arc, occupying part of southeastern Thailand and extending into Cambodia. The Klaeng tectonic line is defined as the boundary between the Chanthaburi terrane and Sibumasu block. The stratigraphy of the Chanthaburi terrane is compared with that of the Sukhothai terrane in Northern Thailand. The Late Palaeozoic-Mesozoic sequences of these two volcanic arc terranes in the Sukhothai Zone share important similarities, but show marked contrasts to those of the Sibumasu and Indochina blocks, where the Late Permian-Triassic is largely absent due to the Indosin...

Abundant and well-preserved marine macrofossils on Seymour Island, Antarctica, provide a valuable resource to establish paleoenvironmental conditions at high southern latitudes during the warm Paleogene. Stable isotope, minor element, and 87Sr/86Sr compositions have been measured for the aragonite bivalve Cucullaea from the Eocene La Meseta Formation. The 87Sr/86Sr stratigraphy suggests an early to late Eocene age for the La Meseta Formation. Sea surface temperature estimates based on ?18O values range from 14.5° to 15.5°C in the early and middle Eocene to 10.5°C in the late Eocene. High-resolution sampling along growth structures provides estimates of seasonality in temperature, which decrease considerably up section. To address the relative contribution of temperature and ice volume or salinity to the ?18O record, Sr/Ca was measured and evaluated as a potential independent paleothermometer for Cucullaea.

Over the late Holocene highstand, the shoreline at Poverty Bay, NZ migrated 12km seaward, fed by sediment from the Waipaoa river. Paleo-shorelines indicate steadily decelerating progradation, possibly signaling changes in forcing on the Waipaoa Sedimentary System. To isolate the cause of this progradation slowdown we reconstruct late Holocene tectonics and stratigraphy over the Waipaoa coastal plain and nearshore from 7ka-present. We find that decreasing rates of sediment storage by coastal progradation were driven by increasing tectonic storage in the steadily subsiding but rapidly growing coastal plain, such that net terrestrial storage remained constant at ~0.8Mt/yr. Hence changes in shoreline migration were due to autogenic increases in accommodation rather than allogenic changes in fo...

Most students of the agricultural origins problem have rejected the thesis that climate change was in important causal variable. For example, it is often emphasized that agriculture began at different times in different areas, and that climate change could not therefore have been a significant factor. It is also suggested that climate change at the end of the last glacial could not have been important, because similar changes in climate occurred at the end of the penultimate glaciation without any cultural response. The primary purpose of this paper is to demonstrate that these objections are invalid, and are based on a misunderstanding of: (1) the nature of late-Pleistocene/early-Holocene climate changes; and (2) the ecological context of early agriculture. Alternatively, it is proposed that the more or less synchronous development of agricultural in several widely separated areas of the globe is best seen as an indirect response to changes in climate during the Pleistocene/Holocene transitions. Three common denominators characterize the early centers of agricultural and collectively point to climate changes as a primary factor: (1) all are located in areas that today are characterized by strongly seasonal rainfall regimes; (2) the initial domestication of plants occurred independently at within a very short period of time during and immediately following the Pleistocene/Holocene transition; and (3) the early plant domesticates were either annuals or geophytes, autecologically adapted to seasonality of moisture supply. The implication is that increased seasonality during the Pleistocene/Holocene transition brought about changes in wild plant and animal populations that in turn led to domestication and agriculture.

Abstract in spanish Se describen las características sismoestratigráficas, sedimentológicas y morfológicas del sector de plataforma submarina adyacente al este bonaerense. El trabajo se basa en los resultados obtenidos durante el desarrollo de sucesivos proyectos destinados al estudio de la cubierta sedimentaria del Plioceno-Cuaternario y reciente, utilizando metodologías de relevamiento sísmico de reflexión de media a alta resolución y muestreos de sedimentos. El sector de plataform (more) a estudiado constituye una típica plataforma submarina silicoclástica de margen pasivo, de gran extensión y suave relieve. Su configuración morfológica está caracterizada por relieves aterrazados con una cobertura sedimentaria de depósitos arenosos relicto a palimpsestos que resultaron del retrabajamiento de sistemas costeros de playas, barreras y lagunas litorales durante el retroceso de la línea de costa como consecuencia del ascenso del nivel del mar durante la transgresión postglacial, con una etapa final de remodelado parcial durante el descenso del nivel del mar del Holoceno superior. Se diferencian dos ámbitos, la plataforma interior ("Terraza Rioplatense", entre la línea de costa y los 30/40 m de profundidad) con geoformas ajustadas a la hidrodinámica actual, y la plataforma exterior (entre la isobata de 70 m y el borde exterior de la plataforma en transición al talud), con sedimentos relicto de poca movilidad; en ambas se hallan relieves pre-transgresivos labrados en depósitos marinos y continentales del Plio-Pleistoceno que afloran bajo la cubierta sedimentaria reciente. Un escalón abrupto de 30/40 m de desnivel separa ambas plataformas. La secuencia estratigráfica estudiada está constituida por seis Secuencias Depositacionales (SD 1 a SD 6 de techo a base) que representan paquetes sedimentarios separados por discordancias. La SD 6 constituye la base de la secuencia, y corresponde a depósitos marinos del Mioceno correlacionables con las unidades costeras conocida como "Paranense-Entrerriense-Chapadmalense". La SD 5 son depósitos marinos en transición a continentales equivalentes a la Fm Barranca de los Lobos del litoral marplatense y a la unidad conocida como "Fm Puelches Equivalente" del Plioceno. La SD 4 está caracterizada por sedimentos marinos correspondientes al denominado "Interensenadense" en el litoral bonaerense, de edad aproximada a los 2,41 Ma (Plioceno superior), y se reconocen en ella diversas sismofacies de ambientes marinos, costeros y continentales con una secuencia litológica granodecreciente hacia arriba. La SD 3, marina, tiene la particularidad de tener una distribución saltuaria, a diferencia de las restantes que se extienden de manera uniforme en toda la región, lo que demuestra la ocurrencia, con posterioridad a su depositación, de importantes procesos erosivos probablemente asociados a tectónica y/o glacioeustatismo. La SD 2 representa a los depósitos marinos-costeros formados durante el estadío isotópico 5e (120 ka), que en las llanuras costeras vecinas se lo conoce como "Belgranense", y está constituida por diversas facies entre las que se destacan barreras-lagunas litorales, playas y estuarios. La SD 1 es la cobertura superficial formada durante la transgresión postglacial en ambientes de barreras-lagunas costeras-estuarios. La secuencia integrada por las SD 5 a 1 representa a las transgresiones glacioeustáticas del Plioceno- Cuaternario, con diferentes grados de preservación en la plataforma y el Río de la Plata en virtud de variantes tectónicas y morfológicas. Existe la posibilidad de que no todas las transgresiones marinas ocurridas en la región hayan quedado preservadas en el registro geológico. Abstract in english The Argentina Continental Shelf (ACS) is one of the largest and smoothest silicoclastic shelves in the world, condition that resulted from its geotectonic setting in a passive margin adjacent to a continental region with very extended and low-lying coastal plains. As a consequence, Pliocene-Quaternary glacio-eustatic sea-level fluctuations have been very important in its modelling and sedimentary characteristics. The study area is located between 35 and 39º S, the wester (more) n boundary is the coastline and the eastern boundary in around 55º W that includes the outer shelf border (Fig. 1). The research is based on middle to high-resolution seismic reflection surveys and bottom/ subbottom sampling (piston cores), carried out in the context of several projects that are part of the Framework Project "Reconocimiento Geológico Geofísico del Margen Continental". The information obtained during these projects, as well as the results coming from previous projects and bibliographic compilation, allowed to gather around 4.000 km of seismic lines, 1.200 bottom samples and 92 piston cores (Fig. 2). Morphology: The ACS shows two major features (Figs. 1 and 3): inner shelf (corresponds to Terrace I, Parker et al., 1997, 1999; Violante, 2005) and outer shelf (northern part of Terrace II, Parker et al., 1997; Violante, 2005). The inner shelf extends from the coastline (or the prodelta front in the de la Plata River outlet) to the 30/40 m isobath, and includes the "Rioplatense Terrace" (RT) which represents the surface that has been modelled during the postglacial transgression but not covered by the late Holocene coastal wedge that constitutes the coastal plains. Several lower-order features modelled by the postglacial transgressive and regressive events developed on the RT surface, as the de la Plata river delta, the linear shoals systems and the La Plata Bank (Fig. 1). On the other hand, relict features composed of semiconsolidated plio-pleistocene sediments as Punta Piedras-Alto Marítimo and Restinga de los Pescadores, are significant elements in the inner shelf morphology. The outer shelf is separated from the inner shelf by a high-gradient step between 40-80 m depth (outer border of RT), which becomes, south and southeast Mar del Plata, of lower relief with a rough surface cut by transverse channels and depressions. Further east from the 80 m contourline, the outer shelf can be subdivided in two sectors: north of Querandí lighthouse it is uniformly dipping towards the shelf border, whereas in the southern part it shows a western depression (90 m depth) closer to the outer border of RT, and a eastern shoal-like elevation (75/80 m depth) near the shelf-slope transition (Fig. 3). Sedimentology: The ACS is a silicoclastic shelf where sediment characteristics and distribution are the result of dynamic, oceanographic and climatic factors. The shelf surface is covered by a relict to palimpsestic terrigenous sandy mantle which is the remnant of reworking of the deposits that constituted ancient coastal environments (barriers, coastal lagoons, estuaries) during the coastline retreat that occurred as a result of the postglacial transgressive event as well as during the sediment redistribution during the late Holocene regressive event (Urien and Ewing, 1974; Parker and Violante, 1982; Parker et al., 1999; Violante and Parker, 2000, 2004). The sandy mantle constitutes in the inner shelf a "shoal retreat massif" (in the sense of Swift, 1976) partially reworked in linear shoals systems; outcrops of the underlying plio-pleistocene substratum - partially covered by a discontinuous sheet of pebbles composed of rock fragments and caliche, beach rocks (coquinas) and sand- are common in some parts of the inner shelf. On the other hand, the outer shelf is mainly characterized by outcrops of the same substratum with minor patches of post-transgressive relict sands with a shoal-like morphology (Fig. 4). Sediment dynamic: Coastal dynamic that influenced Holocene and recent sedimentation is the result of three main sediment transport pathways: a) from the south and southeast as a consequence of the dominant oceanic circulation, that brings the relict sands stored on the shelf surface towards the coastal system, b) the regional northwards littoral transport (coastal currents) parallel to the coastline, although local inversions in the general circulation (littoral cells) are evident in the geological record, as in the Mar Chiquita Lagoon area; this transport redistributes along the coast both the shelf sands and the products of coastal erosion, c) The southwards transport of fine (muddy) sediments from the de la Plata River. Stratigraphy: The Neogene stratigraphy was defined by the application of the seismic stratigraphic method following de concepts of Mitchum et al. (1977). Six Depositional Sequences (named SD 1 to 6 from top to bottom) bounded by major seismic reflectors identified by their seismic attributes (amplitude, frequency and continuity) were recognized (Figs. 4 and 5). SD 6 (base of the sequence): corresponds to marine deposits correlated with the Miocene-Pliocene sediments known as "Paranense-Entrerriense-Chapadmalense" in the adjacent coastal areas (Parker et al., 1994, 2005). SD 5: it has seismic and sedimentological characteristics that indicate marine facies at sea changing to nearshore and fluvial facies towards the coast, and is correlated with the upper Pliocene Barranca de los Lobos Fm as well as with the Puelches Equivalente Fm defined by Yrigoyen (1975) and Parker et al. (1994). SD 4: this unit is broadly extended on the shelf with diverse seismic and litho-facies of marine, nearshore, sublittoral, low-energy coastal and continental environments, with an upwards decreasing grain-size sequence; SD 4 is equivalent to the unit known as "Interensenadense" in the adjacent coastal plains and has an upper Pliocene (2.41 Ma) age. SD 3: it is also marine/littoral and has a unique characteristic given by its discontinuous distribution in the nearshore and coastal regions as well as in some places of the shelf (Figs. 4 and 6) as a consequence of deep post-depositional erosive processes probably produced by intensification of tectonic and/ or glacioisostatic adjustments. SD 2: this unit has again a broad regional distribution, and shows different facies that represent diverse nearshore, coastal and continental environments with the particular characteristic of having been deposited as extensive barriers-coastal lagoon systems (Parker et al., 1999; Violante, 2003); it is correlated with the unit known as "Belgranense" in the adjacent coastal areas, and corresponds to the isotopic stage 5e (120 ka). SD 1: represents the uppermost sedimentary sequence formed during the last postglacial transgressive event; it is constituted by a lower transgressive system tract with different environments such as barriers/lagoons systems and estuaries, and an upper highstand system tract with regressive coastal plains, deltas and a mantle of palimpsestic and relict sands formed by reworking of the previous transgressive deposits; in most of the inner shelf surface their deposits are adjusted to the present hydrodynamic conditions (Urien and Ewing, 1974; Parker et al., 1982). Conclusive remarks: The following conclusions can be highlighted: 1) Major geomorphological features are the inner and outer shelf, which correspond to two topographically and sedimentologically different terraces separated by a step. The upper terrace (inner shelf) is a significant feature in the region which is named "Rioplatense Terrace". 2) From the sedimentological point of view, the shelf is silicoclastic; surface deposits resulted from the postglacial transgressive-regressive event. The main difference between the inner and outer shelf is given by the predominance of palimpsestic deposits in the first one and relict deposits with outcrops of the underlying Pliocene-Pleistocene substratum in the second one. 3) The Neogene stratigraphy is defined by seismicstratigraphic units representing Depositional Sequences (SD), which have been characterized on the basis of their seismic and lithological aspects and correlated with geological units known in the adjacent coastal regions. In this way it was described an uppermost, postglacial unit, followed below by a sequence of three transgressiveregressive units equivalent to the "Pampean" (Plio-Pleistocene) deposits, then a underlying unit corresponding to the "Puelches" (upper Pliocene) sands and finally the basal unit correlated with the "Paranense-Entrerriense- Chapadmalense" (Miocene-Pliocene) sequence. 4) Each SD shows a vertical sequence grading from marine (in the base) to continental (in the top) deposits in an upward decreasing grain-size distribution, therefore representing an individual and complete transgressive-regressive event. 5) The different degree of preservation of the SD in the shelf and the de la Plata River not only indicates different tectonic-glacioisostatic behaviours between both regions, but also determines the possibility that other transgressive events than those preserved in the shelf could have occurred but later completely eroded without leaving any record of their deposition.

The turtle grass (Thalassia testudinum) community has a significant influence on sedimentation in Florida Bay, but the roles other processes may play in the buildup of mud bank and spit sediments are poorly understood. Samples from cores taken from Ramshorn Spit and Ramshorn Shoal were classified into 4 basic types on the basis of particle size distribution, organic content, and faunal assemblages. In order of increasing volumetric importance they are: (1) very thin, discontinuous shelly packstones, representing overbank or storm deposits; (2) thin, continuous basal shelly packstones, the initial marine deposit on the Pleistocene bedrock surface; (3) muddy wackestones, of variable thickness, deposited in the presence of a seagrass community; (4) very thick, faintly laminated fine mudstones, with very sparse fauna, representing weak current-transported sediments settling out of suspension. Discriminant function analysis confirms the classifications and shows that these sediment layers are indeed correlatable between cores. Interpretation of the core logs from Ramshorn Spit indicates a definite change in stratigraphy southwestward from the spit and bank junction to the tip of the spit itself. The different sediment layers show a small but significant inclination to the southwest. Throughout its depositional history, Ramshorn Spit seems to have been actively accreting outward into the surrounding lake by means of a current-transported fine mud fraction. After settling out at the growing tip of the spit, the sediments are subsequently stabilized at some later time by a turtle-grass cover.

The Neogene turbidite systems of northern Green Canyon and Ewing Bank lease areas in the northern Gulf of Mexico are a major exploration play. The regional sequence stratigraphic framework for this area has been interpreted to help define potential areas for future exploration. The study area includes 17 fields/discoveries primarily in turbidite-related reservoirs. Once the sequence stratigraphic framework was established, the existing fields and potential prospects can be quickly evaluated in terms of sequence stratigraphy. Good potential for future exploration exists both in sub-salt prospects and in the deeper water portions of the area. For example, two discoveries (GC 200/244, 506) have been made during the past year. Two main potential reservoir intervals have been identified, which reflect different Winds of turbidite systems based upon lithologies and seismic facies. Lower Pliocene sediments (5.5 to 3.0 Ma) consist of sand-rich turbidite systems (up to 50 % sand in some sequences). Sand bodies are interpreted to be a really widespread sheet and amalgamated sheet sands. The lower Pleistocene interval (1.9 to 0.7 Ma) is predominantly shale-rich with localized thick sands developing in channel-levee systems and unchannelized sands (basin-floor fans). Most of the reservoirs in the area occur within this interval.

The Rio Grande rift provides an excellent field laboratory to study the nature of geothermal systems in an extensional environment. Much of the geologic complexity that is found in the Basin and Range is absent because the rift is located on cratonic crust with a thin and well-characterized Phanerozoic stratigraphy and tectonic history. On the other hand, the Neogene thermo-tectonic history of the rift has many parallels with the Basin and Range to the west. The geology of the southern Rio Grande rift is among the best characterized of any rift system in the world. Also, most geologic maps for the region are rather unique in that detailed analyses of Quaternary stratigraphic and surficial unit are added in concert with the details of bedrock geology. Pleistocene to Holocene entrenchment of the Rio Grande and tributaries unroofs the alteration signatures and permeability attributes of paleo outflow plumes and upflow zones, associated with present-day, but hidden or ''blind,'' hydrothermal systems at Rincon and San Diego Mountain.

A regional sequence stratigraphic analysis was recently completed for the Tertiary slope sediments in Green Canyon, Ewing Bank, and Mississippi Canyon to provide a chronostratigraphic framework for basin reconstructions and to predict lithofacies distributions of reservoir and seal rocks. Sixteen third-order sequences of lowstand deepwater deposits were interpreted for the Middle Miocene-Pleistocene section. Thirty regional lithofacies maps were made of predominantly lowstand deposits showing the distribution of shale and sand-prone sediments, slumps, channel/levee systems, and fan lobes based on distinctive seismic reflection and well log patterns. These maps were combined with isochrons of selected sequences to identify depositional fairways, depocenters, and paleosalt positions that constantly changed through time. Depositional trends were principally north-south but were also observed to be east-west as salt modified the gradient on the gently dipping slope. In some cases, the structural and stratigraphic trends could be projected under allochthonous tabular salt. Miocene channel and fan lobe sands were concentrated on the middle-lower paleoslope across the study area. The sedimentation rate doubled to 2.3 m/1000 yr in the early Middle Pliocene, which caused large-scale salt movements and trapped sand-prone turbidities along the upper to middle slope. A four-fold decrease in sediment influx during the Late Pliocene-Early Pleistocene produced a stacked condensed section of four sequences over the eastern Louisiana slope. A return to rapid sedimentation (up to 6.9 m/1,000 yr) during the Late Pleistocene reactivated salt movements and depocenters in the Green Canyon, Ewing Bank, and Mississippi Trough areas.

New geologic mapping of the western Grand Canyon and the Arizona Strip region, northwest Arizona, reveals young fault scarps on all faults, horsts, and graben structures. Tectonic activity here was previously thought to be at least Miocene age and older. New K-Ar age data for basalt flows in this region provide a basis for determining the age of surficial deposits in relation to elevated structural landforms. The basalts range in age from middle Miocene to late Pleistocene (17 Ma to 0.14 Ma). The Miocene basalts are found in the western Grand Canyon area and are progressively younger in a northeast direction onto the Shivwits and Uinkaret Plateaus, a distance of about 100 km. The older basalts are generally petrographically and chemically distinct from younger basalts. Those younger than one million years have less olivine and are chemically more iron- and titanium-rich suggesting they are from less primitive magmas. Basalt flows in this region older than 1 million years, are cut by faults showing equal displacement of the underlying strata and the flows. Basalt flows younger than 1 million years show offsets as much as 12 to 100 m, less than two-thirds the offset of underlying strata, implying that most tectonic activity occurred within the last 1 to 2 million years. Late Pliocene and Pleistocene faulting has extensively modified the landscape by elevated parts of the terrain resulting in young surficial deposits in lowland areas and rejuvenation of drainages in upthrown fault blocks.

Carbonate deposition at two core sites in the subarctic Pacific (48deg N, 133deg W; 2.9 km and 3.7 km water depth) follows the standard Pacific carbonate cycles, with glacial values being increased over interglacial values. Benthic {delta}{sup 13}C follows the global trend; that is, glacial values are more negative than interglacial values. Comparison with the benthic {delta}{sup 13} record of North Atlantic DSDP Site 552 (56deg N, 23deg W; 2.3 km water depth) shows the North Pacific records to be nearly in phase with and continuously more negative relative to the North Atlantic record. This suggests that concentrations of {Sigma}CO{sub 2(org)} were permanently higher in the North Pacific than in the North Atlantic during the past 750,000 years conceivably supporting the hypothesis that there was no deep-water forming in the late Pleistocene North Pacific. Whereas one would expect that the North Pacific deep waters were continously more corrosive to carbonates than deep waters in the North Atlantic, carbonate deposition at the deep North Pacific core sites is enhanced during glacial periods, and occasionally higher than at shallow North Atlantic Site 552 even though Site 552 was probably above lysocline-depth during most of the late Pleistocene. This apparent paradox can be resolved only by invoking an increase in alkalinity in the glacial North Pacific which would have increased the degree of carbonate ion saturation and thereby improved the state of carbonate preservation. (orig.).

In the present study, we estimated age at death of extinct deer (Cervus astylodon) excavated from two Late Pleistocene sites in Okinawa Island (the Hananda-Gama Cave and Yamashita-cho Cave I sites) from degree of molar wear. This was done using a regression equation of extant sika deer of known age, and deriving an age estimation equation based on M3 crown height applicable to fossil specimens. We then reconstructed mortality profiles using 45 and 88 individuals of the Hananda-Gama and Yamashita-cho assemblages, respectively, and compared the profiles with those of extant and archaeological (Jomon period) sika deer (C. nippon) populations. The reconstructed age profiles of both sites were strikingly different from the living and hunted Jomon period profiles in relative abundance of old adults. They were more similar to the attritional mortality profiles of the extant sika deer that died by natural causes (i.e. not by human or animal predation), but showed a further shift towards older age. Combined with the fact that there is no fossil evidence of medium- to large-sized carnivores on Okinawa Island during the Late Pleistocene, our results suggest that C. astylodon populations had extended longevity because of low predatory pressure, including that by Paleolithic human hunters.   

Early theories concerning geothermal recharge in the Great Basin implied recharge was by recent precipitation. Physical, chemical, and isotopic differences between thermal and non-thermal fluids and global paleoclimatic indicators suggest that recharge occurred during the late Pleistocene. Polar region isotopic studies demonstrate that a depletion in stable light-isotopes of precipitation existed during the late Pleistocene due to the colder, wetter climate. Isotopic analysis of calcite veins and packrat midden megafossils confirm the depletion event occurred in the Great Basin. Isotopic analysis of non-thermal springs is utilized as a proxy for local recent precipitation. Contoured plots of deuterium concentrations from non-thermal and thermal water show a regional, systematic variation. Subtracting contoured plots of non-thermal water from plots of thermal water reveals that thermal waters on a regional scale are generally isotopically more depleted. Isolated areas where thermal water is more enriched than non-thermal water correspond to locations of pluvial Lakes Lahontan and Bonneville, suggesting isotopically enriched lake water contributed to fluid recharge. These anomalous waters also contain high concentrations of sodium chloride, boron, and other dissolved species suggestive of evaporative enrichment. Carbon-age date and isotopic data from Great Basin thermal waters correlate with the polar paleoclimate studies. Recharge occurred along range bounding faults. 151 refs., 62 figs., 15 tabs.

Large-scale interaction between the Continental Intercalaire and the Djeffara aquifer systems in the southeast of Tunisia has been investigated with the aid of chemical and isotopic tracers. Two distinct groundwater types have been identified: (1) the Continental Intercalaire groundwater characterized by elevated temperatures (50-61.4°C), low ?18O (-8.4 to-7.87) and ?2H (-67.2 to-59) values and negligible radiocarbon content, both testifying its great age dating from the late Pleistocene period, and (2) the Djeffara groundwater with distinctly heavier isotopic composition (?18O = -8.31 to -5.80, ?2H = -65.9 to -31.9). The Djeffara groundwaters reveal a distinct changes of physico-chemical and isotopic parameters near El Hamma Faults in the northwestern part of the Djeffara basin. These changes could possibly be explained by a vertical leakage from the Continental Intercalaire aquifer through El Hamma Faults. The mixing proportions inferred from stable isotope mass balance prove that the contribution of the Continental Intercalaire to the recharge of Djeffara aquifer is very significant and may reach 100% in the El Hamma region and in the northern part of Gabes. Isotope tracers strongly suggest that recent recharge to the Djeffara aquifer system is very limited. Its current yield, particularly in its central and northern parts can be maintained only thanks to large-scale underground inflow from the Continental Intercalaire aquifer system, which carries late Pleistocene palaeowater. Consequently, current exploitation of groundwater resources of the Djeffara aquifer has non-sustainable character.

The Upper Arkansas River basin has experienced notable large floods, including the event of 2-6 June 1921 that devastated the city of Pueblo, Colorado. We investigated flood and paleoflood hydrology at strategic sites to determine the frequency and geographic extent of extreme floods within the basin for a dam safety application. Streamgage, historical, and paleoflood data were utilized to develop frequency curves at sites near Salida, Cotopaxi, Parkdale, and Pueblo. Soil/stratigraphic descriptions, radiocarbon dating, and hydraulic modeling were used to estimate paleoflood nonexceedance bounds at the four sites, which ranged from 400 to 2200 YBP for late Holocene surfaces to late Pleistocene surfaces near Cotopaxi. Peak-flow data are from lower-magnitude snowmelt runoff in May and June in...

New data are presented for late Holocene relative sea-level changes in two coastal sites of Sicily and Calabria, southern Italy. Reconstructions are based on precise measurements of submerged archaeological remains that are valuable indicators of past sea-level position. The archaeological remains are millstone quarries carved on sandstone coastal rocks and nowadays partially submerged which, to the authors' knowledge, are used for the first time as sea-level markers. Millstones of similar typology are located on the coast of Capo d'Orlando (northern Sicily) and Capo dell'Armi (southern Calabria). When the archeologically-based sea-level position is compared with the shoreline elevation provided by geological markers (Holocene beachrock, Late Pleistocene marine terraces), a refined underst...

Samples collected from the shelf-edge wedge using surface grab samples and the Jago submersible constrain the KwaZulu-Natal shelf-edge wedge to a late Pliocene age on the basis of the absence of Gephyrocapsa oceanica s.l. and Discoaster brouweri, and the presence of Calcidiscus macintyrei. This correlates with proposed Tertiary sea-level curves for southern Africa and indicates relative sea-level fall during the late Pliocene coupled with hinterland uplift. Exposed failure scarps in the upper portions of submarine canyons yield sediment samples of early Pleistocene ages, indicating the uppermost age of deposition of clinoform topsets exposed in the scarp walls. Partially consolidated, interbedded silty and sandy deposits of similar age outcrop in the thalweg of Leven canyon at a depth of 1...

Abstract The wild horse Equus ferus was one of the most frequent species of the Late Pleistocene large ungulate fauna in Eurasia and played an important role in the subsistence of human groups, especially at the end the Late Glacial. It is frequently assumed that E. ferus became extinct in Europe at the beginning of the Holocene because of the development of woodlands and loss of open habitats. Because of its preference for open habitats and in spite of its adaptability, the appearance or disappearance of the wild horse could therefore be a suitable palaeoecological indicator for the opening of the Holocene primeval woodlands. We revised the dating and reliability of the subfossil record and dated several bones by atomic mass spectrometry 14C dating. From the beginning of the Holocene (960...

Sediment instabilities are common on the prodeltas of the seismically active continental margins of Western Greece. Sediment failures on the low-angle (0.5??2?) prodelta slopes manifest themselves as successions of peripheral rotational block slumps restricted to the foresets of the late highstand systems tract (HST). The individual slump blocks are about 80?150?m long and are bounded by growth faults acting as curved slip planes that extend to a mean depth of 10?15?m below seafloor. Shear planes develop in the lower part of muddy and/or gas charged HST foresets. Deeper basal transparent muddy layers of the early HST bottomset, together with the late Pleistocene transgressive systems tract sequences (TST), are mostly unaffected. On the steeper (2??6?) fan delta slopes of the western Gulf o...

Understanding the relative control exerted by autogenic factors, such as changes in sediment supply, local subsidence and inherited topography, is of crucial interest for a thorough comprehension of the sedimentary evolution of late Quaternary coastal systems. Through an example from the Arno coastal plain, in Tuscany, we show to what extent sedimentation of the Holocene succession, even after the time of maximum marine ingression, was influenced by the presence of a buried 5-7km-wide incised-valley system, generated by the Arno River during the late Pleistocene in response to the last glacial sea-level fall. A prominent stratigraphic marker (locally known as ''pancone''), ca. 5-15m thick, made up of extremely soft and homogeneous organic-rich clays, is reported from the upper 20-30m of th...

Our current understanding of mid-Cretaceous global change is largely based on investigations of pelagic sections from southern Europe and deep sea drilling sites. Much less information exists from other continents and from hemipelagic sections deposited on continental margins. This investigation seeks to broaden our understanding of mid-Cretaceous global change by focusing on the record from hemipelagic sections deposited along the continental margin of northeastern Mexico. The major goals are to compare the record, timing, and extent of the Oceanic Anoxic Events (OAEs) in Mexico and other areas, and to determine the relationship between these events and the global burial of organic material using carbon isotopes. We have investigated four sections from the Sierra Madre Oriental, integrating biostratigraphy, magnetostratigraphy and carbon isotope stratigraphy. Carbon isotopes, measured on the organic carbon (Corg) fraction, show identical stratigraphic changes to curves from Barremian to lower Albian European and Pacific deep-sea sections. Our results add new detail to the C-isotope stratigraphy of the middle and late Albian interval. Three abrupt peaks in Corg content correlate with OAE1a (early Aptian), OAE1b (early Albian) and an event in the late Aptian Globigerinelloides algerianus Zone. All three events are marked by short-term, 0.5-3 per mil decreases in C-isotope values followed by increases of similar magnitude. The decreases may reflect changes in the type of Corg, the nature of carbon cycling, or an increase in hydrothermal activity. The increases in C-isotope values reflect widespread burial of Corg. The similar shape of the C-isotope curves in Mexico and other areas, and the response of C-isotopes to the OAEs, indicate that the late Aptian episode was extensive, and that OAE1a and OAE1b were global. The three anoxic events appear to correlate with rising relative sea level. OAE1a also corresponds to major changes in nannofossil assemblages; the well-known \\

In Hokkaido to Sakhalin, Late Cenozoic compressional processes have produced N-S trending fold-and-thrust belts. Active tectonics started in late Pliocene time (Ito, 1999) was poorly constrained from the previous studies on seismicity, geodesy and structural geology because of the complicated tectonic framework. In northern Hokkaido, coarsening upward Pliocene-Pleistocene basin-fill successions, which named the Koetoi, Yuchi and Sarabetsu Formations in ascending order, have been deformed by west verging stepped folds structures. The Teshio fault zone constitutes the frontal part of the fold-and-thrust belts and contributes to the history of uplifting along the western coast of northern Hokkaido. Terraces distributed in the study area are classified into Higher terraces group (Terrace I-III), Middle terraces group (Terrace IV) and Lower terraces group (Terrace V-VI). On the basis of tephrochronology and 14C dating methods, Terrace IV and VI are correlated with MIS 5e and 1, respectively (Koike and Machida eds, 2001). The author clarifies the tectonic processes of the Teshio fault zone by using the dislocation model and balanced cross-sections to determine the Plio-Quaternary shortening deformation. The N-S trending Kitakawaguchi anticline is a typical fault-propagation-fold defined by a steeply west dipping forelimb and a more gently east dipping and broader back limb. Western part of the anticline, the Yuchi Formation has up to 30° dip to the west, and Terrace II and IV tilt westward. The elevation of the shoreline angle of Terrace IV and II are about 55-60 m and 110 m a.s.l., respectively. The Kitakawaguchi anticline has started to grow in the Early Pleistocene when the Yuchi Formation deposited, and has continued to move during Late Pleistocene time, shown in the seismic reflection profile (Ogura and Kamon, 1992). The Teshio fault zone extends 5-10 km west off shore farther south of the Kitakawaguchi anticline. According to Hydrographic Department, Maritime Safety Agency (1992, 1994), Early-Middle Pleistocene successions containing stratigraphic growth architecture have thickly deposited in front of the forelimb of the flexure. In consideration of the Late Pleistocene to Holocene uplift of the coastal area, the Teshio fault zone has continued to develop during Quaternary. In order to evaluate the activity of the Teshio fault zone, Echigo et al. (2006) simulated the surface deformation for the blind thrust beneath the Teuri and Yagishiri islands using the dislocation model. Assuming a east- dipping (20°) fault for a total length of 40 km at depth of -500 to -800 m a.s.l., the amount of net slip since the Last interglacial is calculated at 50 m, and the average slip rate attains to 0.40 mm/yr. Further studies are needed to constrain the amount and rate of shortening since late Pliocene time.

Global climate is tightly correlated with and controlled by the amount of CO2 in the atmosphere, and both show frequencies of orbital insolation on glacial-interglacial timescales. However, the 'black box', i.e. the mechanisms that control atmospheric CO2 and climate, remain enigmatic. Soil organic carbon pools in northern permafrost regions have long been extremely underestimated and may exceed 1670 Pg - more than twice the atmospheric carbon pool. The reason for this large 'permafrost carbon' storage is that cold and waterlogging conditions are favorable for the preservation of soil organic matter, which more than compensates for low biomass productivity. Recent findings of increasing CO2 and methane emissions from warming and thawing permafrost ecosystems have fueled concerns about strong positive climate feedbacks, but the potential role of permafrost carbon dynamics for atmospheric CO2 levels and global climate on glacial-interglacial timescales has largely been ignored. I propose a conceptual model - the permafrost glacial hypothesis - to explain the rhythm of the Pleistocene ice ages based on the strong positive climate feedback related to insolation-driven permafrost carbon dynamics: 1. Obliquity is the dominant mean annual insolation signal at high latitudes, and obliquity forcing of permafrost carbon dynamics can thus readily help explaining the '40 ka world', i.e. the pronounced 40 ka cyclicity of the ice ages, during the early Pleistocene. 2. The long-term Pleistocene cooling trend led to an expansion of permafrost areas to lower (~45°N) latitudes at ~1 Ma. Here, integrated annual insolation is no longer controlled by obliquity, but by eccentricity. As a consequence, obliquity cycles (glacial terminations) were skipped, unless they coincided with increasing eccentricity, resulting in ~80 or 120 ka glacial cycles and marking the Mid-Pleistocene Transition. The characteristic saw-tooth pattern of the ~100 ka ice ages during the Late and Middle Pleistocene could be readily explained with slow accumulation of permafrost carbon, and rapid release once substantial thawing set in. It should be emphasized that most studies and models today assume a net transfer of terrestrial carbon into the ocean during glacials based on 13C measured on foraminifera shells. This would obviously be inconsistent with the permafrost glacial hypothesis, yet the carbonate ion effect provides a viable alternative interpretation of the measured 13C signals in the ocean.

The main goal of this paper is to analyze the late Quaternary alluvial record of the Andean piedmont between 33° and 34°S (Mendoza, Argentina) reconstructing the prevailing paleoenvironmental conditions and discussing their regional significance. The analysis was carried out along the outcrops of Arroyo La Estacada and its tributary Arroyo Anchayuyo, complementary sections were described at Arroyo Grande and Arroyo Yaucha. The sedimentological, stratigraphical and geochronological (radiocarbon and OSL dating) results as well as the paleoenvironmental interpretation are presented and discussed on the basis of the geomorphological units identified at the piedmont fluvial systems.Late Quaternary deposits of Arroyo La Estacada compose three main geomorphological units consisting of an extensive aggradational plain, a fill terrace and the present floodplain -which is not analyzed in this contribution-. At the aggradational plain a distal alluvial fan lithofacial association was determined, mainly related to overbank sheet fluid overflows and probably temporary inactive channels of sandy-like braided streams between ˜50 ka BP and the early Holocene. The mid-late Holocene fining upward alluvial sequence of the fill terrace corresponds to a sinuous fluvial system lithofacial association. The mid-to late Holocene alluvial sequence exposed at Arroyo Grande banks shows a fining upward sequence probably related to a sinuous fluvial system lithofacial association. Finally, in the Arroyo Yaucha the upper and lower terraces analyzed in this study record a Late Glacial and Holocene fining upward alluvial sequence of a sinuous fluvial system lithofacial association.The late Pleistocene - early Holocene dynamic of the Andean piedmont documents an interval of alluvial aggradation characterized by the occurrence of sandy systems similar to braided rivers in the distal fan environments. The mid-late Holocene is marked by aggradation in sinuous fluvial systems and by two major episodes of degradation registered across the fluvial systems of the study area. This paleoenvironmental reconstruction allowed us to propose an evolutionary scheme and chronology of the major fluvial landscape landforms contributing to the general understanding of the sedimentological and geomorphological dynamic during the late Quaternary.

The Monterrey salient was examined using Landsat TM and MSS images to determine factors controlling the development, distribution, and exposure of Laramide structures. Lateral Mesozoic facies changes influence structural styles and distribution. Exposure of deep foreland structures north of Monterrey is partly related to the location of the Cupido reef trend. Structure along the front of the salient changes abruptly from tectonic wedging to normal overthrusting where deltaic clastics of the Difunta Group grade into incompetent Mendez shale. Salt thickness is an important factor controlling structural development. Areas without evaporites are usually persistent basement highs characterized by less severe deformation. Areas with thin evaporites have complex structural styles, depending on stratigraphy, depth of exposure, and distance from the Sierra Madre thrust front. Thick salt, apparently in a Jurassic rift beneath the salient, facilitated the northward transport of thrust sheets. Late Cretaceous salt movement influenced stratigraphy in La Popa basin where limestone lenses developed in the clastic Difunta Group. Basement topography is the major factor controlling development, style, distribution of structures, and areal distribution of salt and lateral facies changes. The authors propose a tectonic model that explains the large scale structural styles in the region. The Coahuila basement-high block acted as a buttress during Laramide shortening, limiting northward progression of deformation west of Saltillo. East, in the Monterrey salient, the effect of deeper basement and thick salt permitted thrusts to transport material much farther north, resulting in development of a north-south zone of distributed left-lateral shear in the region of Saltillo.

Despite the century-long recognition of regional epeirogeny along the middle Atlantic passive margin, relatively few studies have focused on understanding postrift uplift mechanisms. Here, we demonstrate that epeirogenic uplift of the central Appalachian Piedmont and subsidence of the Salisbury Embayment represent first-order, flexural isostatic processes driven by continental denudation and offshore deposition. Our results show that regional epeirogenic processes, present on all Atlantic-type passive margins, are best resolved by specific stratigraphic and geomorphic relationships, rather than topography. A simple one-dimensional geodynamic model, constrained by well-dated Baltimore Canyon trough, Coastal Plain, and lower Susquehanna River (Piedmont) stratigraphy, simulates flexural deformation of the U.S. Atlantic margin. The model represents the passive margin lithosphere as a uniformly thick elastic plate, without horizontal compressive stresses, that deforms flexurally under the stress of strike-averaged, vertically applied line loads. Model results illustrate a complex interaction among margin stratigraphy and geomorphology, the isostatic response to denudational and depositional processes, and the modulating influence of exogenic forces such as eustasy. The current elevation, with respect to modern sea level, of fluvial terraces and correlative Coastal Plain deposits or unconformities is successfully predicted through the synthesis of paleotopography, eustatic change, and margin flexure. Results suggest that the middle U.S. Atlantic margin landward of East Coast Magnetic Anomaly is underlain by lithosphere with an average elastic thickness of 40 km (flexural rigidity, D = 4 × 1023 N m), the margin experiences an average, long-term denudation rate of approximately 10 m/m.y., and the Piedmont has been flexurally upwarped between 35 and 130 meters in the last 15 m.y. Long-term isostatic continental uplift resulting from denudation and basin subsidence resulting from sediment loading are accommodated primarily by a convex-up flexural hinge, physiographically represented by the Fall Zone. Our results elucidate an inherent danger in using topography alone to constrain late-stage passive margin deformation mechanisms. Only through careful synthesis of field stratigraphic and geomorphic elements such as fluvial terraces, Coastal Plain deposits, and offshore stratigraphy can age control be extended from the offshore depositional setting to the erosionally dominated continent. This study demonstrates that despite a relatively subdued topography, the middle U.S. Atlantic margin experiences progressive flexural isostatic deformation similar to that proposed for high-relief margins characterized by great escarpments. Thus margin topographic diversity remains a function of other factors, such as lithospheric composition and/or structure, supracrustal stratigraphy and structure, degree of drainage integration, drainage divide migration, and climate.

Quaternary sedimentary deposits along the structural depression of the San Andreas fault (SAF) zone north of San Francisco in Marin County provide an excellent record of rates and styles of neotectonic deformation in a location near where the greatest amount of horizontal offset was measured after the great 1906 San Francisco earthquake. A high-resolution gravity survey in the Olema Valley was used to determine the depth to bedrock and the thickness of sediment fill along and across the SAF valley. In the gravity profile across the SAF zone, Quaternary deposits are offset across the 1906 fault trace and truncated by the Western and Eastern Boundary faults, whose youthful activity was previously unknown. The gravity profile parallel to the fault valley shows a basement surface that slopes northward toward an area of present-day subsidence near the head of Tomales Bay. Surface and subsurface investigations of the late Pleistocene Olema Creek Formation (Qoc) indicate that this area of subsidence was located further south during deposition of the Qoc and that it has migrated northward since then. Localized subsidence has been replaced by localized contraction that has produced folding and uplift of the Qoc. This apparent alternation between transtension and transpression may be the result of a northward-diverging fault geometry of fault strands that includes the valley-bounding faults as well as the 1906 SAF trace. The Vedanta marsh is a smaller example of localized subsidence in the fault zone, between the 1906 SAF trace and the Western Boundary fault. Analyses of Holocene marsh sediments in cores and a paleoseismic trench indicate thickening, and probably tilting, toward the 1906 trace, consistent with coseismic deformation observed at the site following the 1906 earthquake. New age data and offset sedimentary and geomorphic features were used to calculate four late Quaternary slip rate estimates for the SAF at this latitude. Luminescence dates of 112 186 ka for the middle part of the Olema Creek Formation (Qoc), the oldest Quaternary deposit in this part of the valley, suggest a late Pleistocene slip rate of 17 35 mm/year, which replaces the unit to a position adjacent to its sediment source area. A younger alluvial fan deposit (Qqf; basal age ˜30 ka) is exposed in a quarry along the medial ridge of the fault valley. This fan deposit has been truncated on its western side by dextral SAF movement, and west-side-down vertical movement that has created the Vedanta marsh. Paleocurrent measurements, clast compositions, sediment facies distributions, and soil characteristics show that the Bear Valley Creek drainage, now located northwest of the site, supplied sediment to the fan, which is now being eroded. Restoration of the drainage to its previous location provides an estimated slip rate of 25 mm/year. Furthermore, the Bear Valley Creek drainage probably created a water gap located north of the Qqf deposit during the last glacial maximum ˜18 ka. The amount of offset between the drainage and the water gap yields an average slip rate of 21 30 mm/year. Finally, displacement of a 1000-year-old debris lobe approximately 20 m from its hillside hollow along the medial ridge indicates a minimum late Holocene slip rate of 21 25 mm/year. Similarity of the late Pleistocene rates to the Holocene slip rate, and to previous rates obtained in paleoseismic trenches in the area, indicates that the rates may not have changed over the past 30 ka, and perhaps the past 200 400 ka. Stratigraphic and structural observations also indicate that valley-bounding faults were active in the late Pleistocene and suggest the need for further study to evaluate their continued seismic potential.

Cretaceous thrust structures are found along the front of the Verkhoyansk miogeoclinal fold belt along the eastern boundary of the Siberian platform in northeast Asia. The Verkhoyansk thrust front is subdivided into a number of segments, each of which has its own thrust system geometry. Balanced cross sections have been constructed for each segment on the basis of the structural study of surface geology and available seismic and drilling data. Distinctions between the segments are also expressed in gravity anomalies and modern topography. Analysis of vitrinite reflectance shows that folding of the Verkhoyansk thrust front was initiated during sedimentation as early as in the Late Jurassic. This period marks the beginning of the collision between the Siberian continent and the Kolyma-Omolon superterrane, now located 500 km to the east of the Verkhoyansk thrust front. Deformation of the thrust front ended by the late Late Cretaceous; erosion of the frontal anticlines began in the early Late Cretaceous. The frontal thrust structures formed in the Late Cretaceous were rejuvenated during a middle to late Pleistocene reactivation, which produced the modern mountain topography. The least amount of erosion of the Verkhoyansk thrust front, 840 m, is observed in its central part, in the Kuranakh segment. To the north and south the erosion increase to 1500 m and 2100 m, respectively. The general configuration of the Verkhoyansk fold belt and its frontal structures are defined by the geometry of Devonian rift-related structures on the eastern Siberian platform and the principal direction, approximately east-west, of Late Cretaceous compressional stresses.

Numerical ages derived from strontium-isotope stratigraphy of 81 Late Turonian-Maastrichtian rudist localities from the Caribbean to Oman are used to establish stratigraphical ranges of readily identifiable taxa of rudist bivalves (Hippuritida). Based on these ranges, seven biozones for the Turonian-Maastrichtian of the central-eastern Mediterranean Tethys, and three biozones for the mid-Campanian-Maastrichtian of the Arabian Plate are established. Most of these are interval zones, each based on the first stratigraphical appearance of the nominal taxon. Micro-evolutionary patterns such as phyletic size increase have been demonstrated for some of the nominal species, as well as a trend of stratigraphical range expansion from the Turonian to the Maastrichtian. Implications of the geochronolo...

What circulation pattern drove Southern Alps glacial advances at ~21 ka? Late 20th century glacial advances in New Zealand are commonly attributed to a dual precipitation increase and cooler than normal temperatures associated with enhanced westerly flow that occur under synoptic pressure patterns termed 'zonal' regimes (Kidson, 2000). But was the circulation pattern that supported major Southern Alps glacial advances during the global LGM similar to the modern analog? Here, a Regional Climate Regime Classification (RCRC) time slice was used to infer past circulation for New Zealand during the LGM at ~21 ka. Palaeoclimate information that supported the construction of the ~21 ka time slice was derived from the NZ-INTIMATE Climate Event Stratigraphy (CES), one new Auckland maar proxy record...

Geological characteristics of reservoirs in southwestern Saskatchewan which influence the productivity of horizontal wells were discussed. Until late 1993 vertical wells had been used to recover oil in the Battle Creek field, however recently drilled horizontal wells indicated potential for much higher yields over shorter time periods. Geographic and geological settings for the reservoir were described. Stratigraphy and depositional history of the Mississippian strata were presented. It was found that diagenesis created two types of non-reservoir rock and three of reservoir grade. Porosities of 8-41%, permeabilities of 8-542 md, and entry pressures of less than 4 kg/cm{sup 2} were found to make up the reservoir rock at several poorly exploited locations in or near the Battle Creek formation. 6 refs., 7 figs.

Mudurnu-Goynuk basin of the Sakarya Zone in NW Anatolia comprises ca. 1500m thick Paleocene-Eocene terrestrial to shallow marine succession overlying the Late Cretaceous deeper marine progradational fore-arc sediments. Formed in a foreland setting in relation to southerly situated Izmir-Ankara suture zone, this terrestrial succession (regionally known as Kizilcay group) comprises a thin (<200m) oil shale-bearing lacustrine section with very good cyclic patterns that potentially serves the quantification of stratigraphy and enlightening the origin of cyclicities of various hierarchy. Our detailed facies analysis on three correlative measured sections showed that mudstone, oil shale and thinner limestone alternations characterize the relatively deeper part of the Eocene lake with probable ma...

The shoreline displacement history of the eastern James Bay lowlands in the last 7 ka has been investigated by means of AMS radiocarbon dating of sediments cored from wetlands. We present twelve radiocarbon dates on macrofossils from six sites spread along a gradient of increasing land age and elevation. Palynomorph analysis (pollen, spores, and dinoflagellate cysts) was used to define the isolation stratigraphy. During the last 7 ka the shoreline elevation has regressed at a decreasing rate. The rate of shoreline emergence was initially rapid (6. 5 m/ 100 yr) between 6850 and 6400 cal yr BP then slowed down to 1.4- 2 m/ 100 yr during the late Holocene. Examination of previous relative sea level data based upon mollusc shells reveals high levels of uncertainty that mask potential temporal ...

We present a preliminary photogeologic map of the Scandia region of Mars with the objective of reconstructing its resurfacing history. The Scandia region includes the lower section of the regional lowland slope of Vastitas Borealis extending about 500-1800km away from Alba Mons into the Scandia sub-basin below -4800m elevation. Twenty mapped geologic units express the diverse stratigraphy of the region. We particularly focus on the materials making up the Vastitas Borealis plains and its Scandia sub-region, where erosional processes have obscured stratigraphic relations and made the reconstruction of the resurfacing history particularly challenging. Geologic mapping implicates the deposition, erosion, and deformation/degradation of geologic units predominantly during Late Hesperian and Ear...

Several large, TCF-size gas fields have been discovered in the Surma Basin, Bangladesh. Detailed sequence stratigraphy was performed on log and seismic data to study these fields and future potential of the area. The prospective section is Upper Miocene sands caught up in a series of younger compressional fault-related folds caused by the Indian Plate colliding with S.E. Asia in the late Tertiary. World-class gas/water contacts are observed on the seismic data over the fields. Sequence stratigraphic techniques reveal an ordered, predictable stratigraphic architecture of sandy highstands and transgressions, and muddy aggraded prograding complexes with deep incisions at each sequence boundary. This serves as a framework to understand the hydrocarbon accumulations in the area. Cyclostratigraphy is used to understand the unusual lithology distributions in the basin.

Lopingian (Late Permian) conodonts and stratigraphy in northwest and central Iran have become hotly debated issues recently. We here use a sample-population approach, to develop a high-resolution conodont biostratigraphic framework for the Lopingian of Iran based on a re-examination of collections studied by Sweet from the Kuh-e-Ali Bashi area, northwest Iran; samples from the Abadeh C section and a nearby Permian-Triassic boundary section in the Abadeh area; and on published data. Six Wuchiapingian conodont zones, the Clarkina dukouensis, C. asymmetrica, C. leveni, C. guangyuanensis, C. transcaucasica and C. orientalis zones, and eight Changhsingian conodont zones, the Clarkina wangi, C. subcarinata, C. changxingensis, C. bachmanni, C. nodosa, C. yini, C. abadehensis and C. hauschkei zone...

Middle to late Holocene alluvium, identified as Quaternary alluvial unit 4 (Qa4), along Kanab Creek in southern Utah, USA was dated using optically stimulated luminescence (OSL) on quartz sand, and by radiocarbon dating of detrital charcoal. Entrenchment beginning in 1882 AD created arroyo walls that expose up to 35 m of the Qa4 alluvium. The stratigraphy and sedimentology suggest that fluvial aggradation along the study reach occurred rapidly. Due to the high sediment supply, short transport distances and semi-arid climate with flashy discharge, partial bleaching (zeroing) of the luminescence signal was expected to be a problem for OSL dating. We approached this problem by first using small-aliquot (20 grains) and single-grain dating of quartz sand to reduce the number of grains contribut...

Glacial-interglacial cycles through the Mid-Pleistocene Transition (MPT; 1.2 to 0.6 Ma) are characterized by a frequency decrease from 41 to 100 kyr and an amplitude increase via more extreme glaciations. This major transition has been the focal point of much North Atlantic paleoceanographic and micropaleontological research, yet little is know about North Atlantic deep-ocean benthic ostracode faunas through the MPT. One might predict such glacial-interglacial cycles to affect ostracode assemblages, yet North Atlantic ODP Sites 980 (1,145 m) and 982 (2,168 m) reveal no major or consistent changes in ostracode accumulation rates, resampled (abundance- corrected) richness, or taxon percent abundances, with the exception of an increase in ostracode accumulation rates late in the MPT at the deeper Site 980. This ostracode faunal stability is consistent with Raymo et al.'s (2004) interpretation of relatively stable North Atlantic thermohaline circulation through the MPT based on carbon-isotope depth-profiles. However, this ostracode faunal stability stands in stark contrast to other North Atlantic ostracode studies of the latest Pleistocene (Didie and Bauch, 2000) and Late Pliocene (Cronin et al., 1996), which show strong faunal variations in response to presumed oscillations in surface export production and intermediate water ventilation associated with glacial-interglacial cycles. Late in the MPT interval (0.8 to 0.6 Ma), benthic foraminifera experience a major decline and preferential extinction of infaunal taxa at Site 980 and 982 (Kawagata et al., 2002). Coeval ostracode assemblages show no comparable taxonomic loss through this enhanced extinction interval, but ostracode accumulation rates do markedly increase at the deeper Site 980. Such differential biotic response under presumably stable benthic environmental conditions remains difficult to reconcile with current paleoceanographic data.

Numerical ages derived from strontium-isotope stratigraphy of 81 Late Turonian-Maastrichtian rudist localities from the Caribbean to Oman are used to establish stratigraphical ranges of readily identifiable taxa of rudist bivalves (Hippuritida). Based on these ranges, seven biozones for the Turonian-Maastrichtian of the central-eastern Mediterranean Tethys, and three biozones for the mid-Campanian-Maastrichtian of the Arabian Plate are established. Most of these are interval zones, each based on the first stratigraphical appearance of the nominal taxon. Micro-evolutionary patterns such as phyletic size increase have been demonstrated for some of the nominal species, as well as a trend of stratigraphical range expansion from the Turonian to the Maastrichtian. Implications of the geochronology of Late Cretaceous carbonate platforms for the biostratigraphy of other benthic fossils are briefly discussed.Three significant gaps in the stratigraphical distribution of rudist localities in the lower, middle, and uppermost Campanian, respectively, correlate with other records of sea-level change, indicating that they correspond to major eustatic sea-level falls. Only a limited number of rudist taxa is evaluated here, but the early and latest Campanian sea-level falls correspond to faunal turnover and extinction of characteristic associations of Late Cretaceous Hippuritida.The final extinction of the Hippuritida at the Cretaceous/Paleogene boundary is evaluated based on the available numerical ages of eighteen Late Maastrichtian localities. Eighteen genera are recorded at the six youngest localities, which thus have a species richness similar to older Late Cretaceous localities. While the ultimate cause for extinction of the Hippuritida must be evaluated on time scales beyond the resolution of strontium-isotope stratigraphy, the data set evaluated provides some insight into the pattern of their demise, which is considered to be the result of a high degree of endemism indicating limited exchange between increasingly isolated populations. This isolation was possibly related to the gradual decrease in the areal extent of Maastrichtian carbonate platforms due to a long-term cooling trend and local tectonics that affected carbonate platform growth in the regions studied.

A study was conducted to classify diatoms in modern sediment surface samples in freshwater sites into assemblages and to assess the historical changes in lake level changes and climatic conditions in Madagascar during the Late Quaternary. Analysis of taxonomic percentages of diatoms in recently deposited sediments from various sites shows that diatom communities in these sites can be grouped by means of cluster analysis into distinct assemblages, some of which show similarities to groupings found in East Africa. pH and conductivity appear to be important factors correlating with differences in diatom communities in these study sites. Trends in diatom assemblages in a sediment core taken from Lake Alaotra, supplemented by those in sediments of the paleolake Ampasambazimba, suggest that the late Pleistocene in northeastern Madagascar was arid, though aridity was probably not as constant or as severe as in many areas of eastern and northern Africa; the Holocene was a period of moderate but variable conditions, marked by a distinct dry episode ca 5000 yr B.P. and a drying trend toward the late Holocene. Changes in diatom assemblages in a sediment core from Lake Kavitaha in central Madagascar suggest changes in the surrounding environment during at least two periods in the late Holocene. These coincide with increases in charcoal influx and, around 700 yr B.P., with the intensification of agricultural activity in the area.

To improve our understanding of the Late Pleistocene and Holocene carbonate system of the western Arabian Sea a high-resolution sedimentary record off Somalia has been analysed. The 15.26-m-long piston core 905 comprises a complete record of the last 90,000 years. We have measured concentrations of carbonate minerals, i.e., aragonite, calcite, Mg-calcite, and element ratios (Sr/Ca) together with pteropod counts and an estimation of the preservation state of pteropod shells to trace temporal changes in carbonate production and preservation. The Sr/Ca ratio shows strong similarities to the aragonite percentage and the ?18O record of the planktic foraminifer Neogloboquadrina dutertrei. High Sr/Ca ratios together with fragments of corals found in the coarse fraction indicate that most of the aragonite is of shallow water origin (high-Sr aragonite) and pteropods contribute much less than expected. High resuspensional input of shallow-marine aragonite occurs during sea-level highstands (interglacials) and low input during lowstands (glacials). The Mg-calcite concentration record resembles the whole pteropod abundance and pteropod shell preservation records confirming the use of Mg-calcite in combination with pteropod preservation proxies to reconstruct past fluctuations in carbonate dissolution. Preservation of aragonite and Mg-calcite increases during stadials, H-equivalents, YD and late Marine Isotope Stage (MIS) 3. During late MIS 5/early MIS 4 and in the Late Holocene absence of few pteropods as well as low Mg-calcite weight percentages point to strong dissolution of aragonite and Mg-calcite.

Diversification of South American species endemic to open habitats has been attributed to both Tertiary events and Pleistocene climatic fluctuations. Nonetheless, phylogeographical studies of taxa in these regions are few, precluding generalizations about the timing and processes leading to differentiation and speciation. We inferred population structure of Hypsiboas albopunctatus, a frog widely distributed in the Brazilian Cerrado. Three geographically distinct lineages were recovered in our phylogeny. The Chapada dos Guimarães (CG) clade was the first to diverge from other populations and contains multiple haplotypes from a single population in western Cerrado, probably representing a cryptic species. The southeast clade (SE) includes populations along the southeastern limit of the range within the historical distribution of the Brazilian Atlantic forest. Finally, the Central Cerrado (CC) group includes haplotypes from the interior of Brazil that are paraphyletic relative to the SE clade. Analyses of historical demography indicate significant population expansion in the CC and SE populations, likely associated with colonization of newly formed open habitats. The divergence of populations in the CG clade occurred in the late Miocene, concordant with the uplift of the central Brazilian plateau. Divergence of the SE clade from the CC occurred during the mid-Pleistocene. Thus, both Tertiary geological events and Pleistocene climatic fluctuations promoted divergences among lineages. Our study reveals a complex history of diversification in the Cerrado, a morphoclimatic domain highly threatened because of anthropogenic habitat alteration. We identified surprisingly deep divergences in a widely distributed frog, indicating that the Cerrado is not a barrier-free habitat and that its diversity is likely underestimated. PMID:22211375

The study of natural analogues has been established as one of the most important methods for validation of concepts and models applied for the assessment of long-term performance of repositories for nuclear waste. The objectives of such studies range from detailed investigations of processes and features on a small scale to attempts of explaining the evolution of whole sites. For studies of specific processes it may well be as important to consider the larger scale settings as boundary conditions. This appreciation of context and an integrated view may be as important for evaluation of most natural analogues as for performance assessments. This is more evident the more the evaluation depends on a knowledge about the evolution of the natural analogue. The attempted formulation of scenarios of the Koongarra Analogue has been based on the external conditions and external features. A rapid weathering of the host rock, i.e. the chlorite schist, is assumed to have started around the onset of the Pleistocene Ice Age (ca 1.6 Ma BP). The eventual oxidation and mobilization of the uranium ore could then have occurred under unsaturated or saturated conditions. This leads to the following major scenarios: (1) Uranyl Phosphates formed under unsaturated conditions, with a periodical evolution of the dispersion fan in conjunction with alternating dry (glacial) and wet (interglacial) periods during the Pleistocene Ice Age; (2) Uranyl Phosphates formed under unsaturated conditions as a single event, taking place either early or late during the Pleistocene Ice Age; (3)Uranyl Phosphates formed under saturated conditions, in conjunction with periods of higher and lower flow due to the climatic cycling. Although the original objectives may not have been fully achieved, this work is believed to contribute to a better understanding of the Koongarra Analogue as well as to give a basis for further scenario work

Over the past five years, deep seismic resolution in the Gulf of Mexico has improved to the point that extensive horizontal salt bodies have been defined and initial drilling has commenced for subsalt reservoirs. This enhancement of the deeper seismic also shows evidence of a related deep and extensive decollement surface or unconformity that divides the geologic section into two separate but very different structural realms. Upper Pleistocene to Miocene sediments are mixed sand and shale, extensively structured by movements of mobile salt/shale and numerous listric growth faults that generally flatten with depth along a common decollement or detachment surface. Below the decollement zone from 15,000 to over 25,000 ft Lower Miocene through Oligocene mostly shaly sediments exhibit more limited structuring and high-angle faults. Most of the horizontal salt injection on the southern Louisiana shelf occurred within the thick deep-water shales that postdate this surface. Later loading by Pliocene-Pleistocene sands and shales caused extensive additional salt movement. Penetrations into the deeper zones are limited, but include wells in Louisiana, South Marsh Island, and Main Pass. The age of the surface varies from early Miocene to late Eocene and is seismically defined by the flattening of overlying listric faults, discordant dips that in some cases appear as angular unconformities, and higher amplitudes along salt surfaces. The exploration potential is currently questionable due to depth, abnormal pressures, and risk of reservoir sands. There is considerable work to be done, however, toward understanding the relationships to hydrocarbon migration, Pliocene-Pleistocene depositions, and overlying structuring.

The application of modern methodological taphonomic approaches to Pleistocene faunal assemblages that were excavated and interpreted before taphonomic analyses became common are critical to verifying whether the original interpretations are valid. Even though taphonomic research is common in North America, Africa, and Europe, few such studies of faunal collections have been carried out in East Asia. In this regard, taphonomic analysis of the faunal assemblage from Hanaizumi, Japan serves as an excellent case study because few taphonomic re-analyses of previously excavated Pleistocene assemblages have been performed in Japan. Hanaizumi was excavated in the 1950s and the original behavioral interpretation was that hunter-gatherers were responsible for the accumulation of the faunal assemblage, which is dominated by bison (Bison priscus). The taphonomic analysis presented here indicates that evidence of human modification is present on the bones. However, results suggest that even though hunter-gatherers may have had primary access to many of the bison in the assemblage, Hanaizumi was probably not a kill site or a hunter-gatherer home base as was originally proposed. Rather, the acquisition of bison may have taken place further up river and Hanaizumi is the locality to which the already processed carcasses were transported via fluvial movement. Accordingly, it is difficult to use the Hanaizumi faunal dataset to address current paleoanthropological debates. Future fieldwork at the site may indicate that hunter-gatherers played a more significant role in the formation of the bison bone assemblage. For now, Hanaizumi is best considered an allochthonous paleontological collection that has assisted in paleoenvironmental reconstructions of Late Pleistocene Japan.   

A previous analysis of Pacific herring mitochondrial (mt) DNA with Bayesian skyline plots (BSPs) was interpreted to reflect population growth in the late Pleistocene that was preceded by population stability over several hundred thousand years. Here we use an independent set of mtDNA control region (CR) sequences and simulations to test these hypotheses. The CR haplotype genealogy shows three deeply divided lineages, A, B and C, with divergences ranging from d=1.6% to 1.9% and with similar genetic diversities (h=0.95, 0.96, 0.94; ?(?)=0.011, 0.012, 0.014, respectively). Lineage A occurs almost exclusively in the NW Pacific and Bering Sea, but lineages B and C are co-distributed in the Northeastern Pacific. This distribution points to a historical allopatric separation between A and B-C across the North Pacific during Pleistocene glaciations. The origins of B and C are uncertain. One hypothesis invokes long-term isolation of lineage C in the Sea of Cortez, but the present-day lack of geographical segregation from lineage B argues for lineage sorting to explain the deep divergence between B and C. BSPs depict rapid population growth in each lineage, but the timing of this growth is uncertain, because of questions about an appropriate molecular clock calibration. We simulated historical demographies under a Pleistocene climate model using observed genetic parameters. BSPs for these sequences showed rapid population growth after the Last Glacial Maximum (LGM) 18-20 k years ago and a flat population history during previous climate fluctuations. Population declines during the LGM appear to have erased signals of previous population fluctuations. PMID:22750109

La Désirade is a small island located east of Grande Terre and Basse Terre, the main islands of the Guadeloupe Archipelago in the Lesser Antilles Arc. La Désirade is an "forearc outer high" located immediately west of the trench where Atlantic crust is presently subducted under the Caribbean Plate. The "Limestone Table" (LT) of La Désirade has been considered as a Plio-Quaternary reefal deposit. However, the prominent feature of this late middle to late Pliocene age. These ages constrain the Neogene vertical tectonic movements of the island. We have also dated Pleistocene terraces and fringing reefs that are in an unconformable contact along paleocliffs with the Mio-Pliocene sediments. In the lower unit of the LT, sedimentary environments alternate between below wave base, muddy carbonates documenting glacioeustatic highstads, and wave-bedded, winnowed bioclastic carbonates representing lowstands. In the upper LT unit synsedimentary, tectonic subsidence must have decelerated, resulting in a different sedimentation pattern: Bioclastic limestones probably represent highstand separated by emersion/erosion surfaces resulting from lowstands. A cyclostratigraphic study in the LT has been attempted, but gave unreliable results so far. Erosion/non-deposition indicate that the depositional cycles of the LT are unreliable recorders of both the frequency and the amplitude of orbitally driven sea-level fluctuations. The history of the carbonates begins with initial tectonic uplift and erosion of the Jurassic igneous basement. It occurred before late Miocene times, when sea-level oscillated around a long term stable mean. The rhythmic deposition of the LT can be explained by synsedimentary subsidence during rapidly oscillating, precession-driven (19-21 kyr) glacio-eustatic sea-level in the latest Miocene/earliest Pliocene-late Pliocene. Except for a thin reef cap at the eastern edge of the LT, no in-place reefal constructions occur in the LT. Unfortunately, samples from the reef cap were all severely altered and no 87Sr/86Sr ratios were measured. Pre-late Miocene uplift, Pliocene subsidence and late Pliocene-Pleistocene emergence (up to 200 m above modern sealevel), and westward tilting must be the result of repeated subduction of buoyant ridges along the Caribbean trench located offshore La Désirade.

Cryptotephra of Icelandic origin from the open-air archaeological site of Ahrensh??ft LA 58 D (Kr. Nordfriesland, Schleswig-Holstein), northern Germany overlies a Late-glacial Havelte lithic assemblage, hitherto dated by 14C and biostratigraphy to the earliest part of the Late-glacial interstadial (GI-1e to GI-1c3). Peaks in ash shards are observed in two profiles. Major and minor element geochemistry indicates volcanic ash originating in the Katla system. Precise correlation to previously described tephra is uncertain due to overlapping chemical characteristics. The Ahrensh??ft 14C determinations, litho- and bio-stratigraphy encompass a broad age-span for the cryptotephra bearing sediments, from the end of the Aller??d to the Preboreal. The most plausible volcanic eruption correlates are the Vedde Ash (∼Younger Dryas), already known from the European mainland, tephra AF555 (late Younger Dryas) and the Suduroy tephra (∼Preboreal/Boreal), hitherto recorded only in the North Atlantic region. These three ash horizons have been dated to, respectively, 12,171 ± 57 yr b2k in the NGRIP ice-core, c.11,500 cal BP, in Scotland and c.8000 cal BP, by radiocarbon from the Faroe Isles. Ongoing research on deposits from the type sites for the tephra layers may in the future differentiate these markers leading to better discrimination of the chemistries and a resolution of this question.

The assumption was tested that forest biomass in communities on the modern landscape is equivalent to that in similar communities on the late-Quaternary landscape. Forest carbon storage dynamics during the past 16,000 years were derived from a mathematical model of forest processes and individual tree species behavior. Modern pollen and climate data sets provided pollen-climate transfer functions to generate model driving variables from fossil pollen records. Climate variables were estimated from fossil pollen stratigraphies in Tennessee, Ohio, and Michigan. Only simulated early postglacial warming produced the large carbon gains one would expect in mixed deciduous-coniferous forests from unglaciated regions. The simulated mid-Holocene warming generated little carbon storage response by temperate deciduous forests and large carbon gains in northern hardwood-conifer forests, unlike the linear relationship expected when equivalence is assumed between modern and prehistoric forests. Late-glacial, mid-latitude forests may have contained more biomass than would be expected from equivalent forests on the modern landscape. Simulations of alternate hypotheses to explain the enhanced late-glacial cannot distinguish effects of reduced seasonal temperature extremes from effects of changing species' temperature tolerances. 84 references, 5 figures, 2 tables.

A series of human fossils, the so-called ‘Minatogawa Man’ material, unearthed from the fissure site at the Minatogawa limestone quarry on Okinawa Island, is well known as the best preserved Pleistocene human remains in Japan. Another series of ‘Upper Minatogawa’ human remains was also recovered from the same fissure site. Although the Upper Minatogawa series was supposed to be derived from higher horizons than the Minatogawa series, and this supposition was provisionally supported by the fluorine dating of bones, the chronological and/or stratigraphical relationships of individual human specimens have nevertheless not been clarified. Here we report newly obtained data on the relative chronology of the Minatogawa and the Upper Minatogawa series by additional element analyses (strontium and barium) of bones, and draw the following inferences: (1) the Upper Minatogawa human remains are younger than the Minatogawa human remains (i.e. ‘Minatogawa Man’) as a group; (2) however, a wider age range is implied for the ‘Minatogawa Man’ series, and some of the specimens such as Minatogawa IV and maybe Minatogawa II are comparable in age to the Upper Minatogawa series. Thus, the ‘Minatogawa Man’ series may not comprise a single chronological group, although they may be of one morphological group. We also discuss the geological age of the Minatogawa fossil assemblages, and address preliminary palaeoanthropological implications concerning the population history of the Japanese archipelago in the Late Pleistocene.   

In a previous dynamical model the late Cenozoic climate variations were simulated, taking into account free and forced variations of atmospheric carbon dioxide acting in concert with changes in global ice mass and the deep ocean thermal state, all under the influence of the known earth-orbital radiative changes. This model is now extended by adding another relevant variable, bedrock/asthenosphere depression, including its associated ice-calving effects. Within the context of this extended model we (1) demonstrate the main results of previous bedrock/ice sheet models in what we believe is the simplest possible manner, (2) show how these previous models can exhibit the mid-Pleistocene transition with the inclusion of CO2 effects, (3) discuss the limitations of these previous bedrock models, and (4) illustrate the possibility of removing some of these limitations and accounting for further aspects of the paleoclimate record by using the full dynamical system that includes forced and free effects of CO2, as well as effects of bedrock depression and Milankovitch forcing. As one example of a new possibility, with bedrock effects included in the full system we can obtain a solution characterized by irregularly spaced, intermittent episodes in which the behavior is dominated either by near-40 kyr period oscillations or by near-100 kyr periods (such as prevailed over the Pleistocene).

In the Southern Hemisphere, lacustrine sediments started to be deposited with the beginning of the deglaciation at ca 19,000 cal yr BP. At this time the region of Lake Caço was dominated by sparse and shrubby vegetation with dominance of steppic grasses in a poor sandy soil. The landscape did not present any ecological characteristics of a modern Cerrado. However single pollen grains of two Cerrado indicators, Byrsonima and Mimosa, suggest that some Cerrado species were able to survive under the prevailing arid climate, probably as small shrubs. After 15,500 cal yr BP, a sudden increase in the moisture rates is evidenced with the progressive expansion of rainforest showing successive dominance of various associations of taxa. The development of the forest stopped abruptly at the end of the Pleistocene between 12,800 and 11,000 cal yr BP, as attested by strong fires and the expansion of Poaceae. In the early Holocene an open landscape with a relatively high level of water in the lake preceded the progressive expansion of Cerrado species towards a denser forested landscape; fires are recorded from then on, resulting in the physiognomy of the Cerrado we know today. Late Pleistocene paleoenvironmental records from northern Brazil reflect the interplay between insolation forcing of two hemispheres with the local components represented by the interannual shift of the Inter Tropical Convergence Zone and the influence of seasonal equatorwards polar air incursions.

An excavation at the cave site of Hang Cho in northern Vietnam resulted in the discovery of a terminal Pleistocene human skeleton in a relatively good state of preservation. The material culture from this site belongs to the pre-ceramic Hoabinhian period. An AMS radiocarbon date on a tooth sample extracted from this individual gives a calibrated age of 10450 ± 300 years BP. In discussions of the population history of Southeast Asia, it has been repeatedly advocated that Southeast Asia was occupied by indigenous people akin to present-day Australo-Melanesians prior to the Neolithic expansion of migrants from Northeast Asia into the area. Cranial and dental metric analyses were undertaken in order to assess the biological affinity of early settlers in this region. The results suggest that the Hang Cho skeleton, as well as other early or pre-Holocene remains in Southeast Asia, represent descendants of colonizing populations of late Pleistocene Sundaland, who may share a common ancestry with present-day Australian Aboriginal and Melanesian people.   

The burbot (Lota lota Linnaeus, 1758) is the only freshwater species from the cod family. Various taxonomic hypotheses were tested against molecular data by sequencing the mitochondrial cytochrome b locus of 120 burbot from 41 populations together with the related species Molva molva (ling) and Brosme brosme (tusk), which represented the other Lotinae genera. Within the genus Lota two distinct phylogroups were observed: one in North America south of the Great Slave Lakes (Lota lota maculosa) and one in Eurasia and the remainder of the Nearctic region (Lota lota lota). The burbot lineage separated 10 Myr BP from the other Lotinae, while the genetic variation within burbot appeared to be approximately 1 Myr old. However, fossil evidence suggested that burbot already existed in the Early Pliocene in Europe, from were it probably colonized North America in the Early Pleistocene. While Nearctic burbot survived climatic oscillations and diverged in several refugia, the Eurasian form became extinct or was reduced to a very small population. In the Late Pleistocene the species recolonized the Palearctic region to establish its present distribution range. PMID:14615196

The Earth's asthenosphere and lower continental crust can regionally have viscosities that are one to several orders of magnitude smaller than typical mantle viscosities. As a consequence, such shallow low-viscosity layers could induce high-harmonic (spherical harmonics 50 - 200) gravity and geoid anomalies due to remaining isostasy deviations following Late-Pleistocene glacial isostatic adjustment (GIA). Such high- harmonic geoid and gravity signatures would depend also on the detailed ice and meltwater loading distribution and history. ESA's GOCE satellite mission, planned for launch Summer 2007, is designed to map the quasi-static geoid with centimeter accuracy and gravity anomalies with milligal accuracy at a resolution of 100 kilometers or better. This might offer the possibility of detecting gravity and geoid effects of low-viscosity shallow earth layers and differences of the effects of various Pleistocene ice decay scenarios. For example, our predictions show that for a typical low-viscosity crustal zone GOCE should be able to discern differences between ice-load histories down to length scales of about 150 km. One of the major challenges in interpreting such high-harmonic, regional-scale, geoid signatures in GOCE solutions will be to discriminate GIA-signatures from various other solid-earth contributions. It might be of help here that the high-harmonic geoid and gravity signatures form quite characteristic 2-D patterns, depending on both ice load and low-viscosity zone model parameters.

The deep-water Komandorsky basin is located in the southwestern part of the Bering Sea. On the east, it is separated from the Aleutian basin by the submerged Shirshov Ridge; on the west, it is bordered by structures of the north Kamchatka accretionary prism. The Komandorsky basin is characterized by strongly dissected relief of it acoustic basement, which is overlain by a 1.5 to 2.0-km thick sedimentary cover. The western part of the basin is occupied by a rift zone, which is characterized by modern seismicity and high heat flow. It is considered to be the axial zone of Miocene-Pleistocene spreading. On the north terrace of the Komandorsky island arc, traced active volcanos provide evidence that subduction is occurring under the arc from the north. The spreading rift zone is reflected on the continent in Miocene-Pleistocene volcanic rocks, characterized by typical oceanic tholeiitic composition. The Komandorsky basin formed as a result of spreading during the Maestrichtian. Spreading within the basin occurred during the early and middle Oligocene and the late Miocene. East and west of the spreading axis, accretionary prisms formed. The latter are observed along the western flank of the Shirshov Ridge and on the eastern sides of the Kamchatka Peninsula and Koraginsky Island.

We present the first spatial reconstruction of ice-rafted debris (IRD) deposition and its provenance in the sub-polar North Atlantic Ocean during the earliest large amplitude Pleistocene glacial, marine isotope stage (MIS) 100 (~2.52 Ma). Our flux estimates indicate that the magnitude of IRD deposition during MIS 100 was large with maximum inputs (at ~53 N) comparable to the Last Glacial Maximum (LGM). IRD provenance was determined using laser ablation lead (Pb) isotope analyses of single feldspar grains. We find that the Pb isotope composition (206Pb/204Pb and 207Pb/204Pb) of individual ice-rafted (>150?m) feldspars deposited at DSDP Site 611A, ODP Site 981 and IODP Site U1308 during MIS 100 are very similar to those deposited at the centre of the LGM IRD belt during ambient ice-rafting episodes (Gwiazda et al., 1996a). Based on a comparison to known Pb isotopic composition of potential source regions we propose that abundant iceberg calving sourced from large, multiple circum-North Atlantic Ocean ice-sheets (located on North America, Scandinavia, Greenland and possibly Britain) characterised MIS 100. However, unlike for the LGM, the locus of abundant iceberg melting and IRD deposition may have been situated north of the Last Glacial IRD-belt (~50 N) due to a reduced glacial meridional sea-surface temperature gradient relative to the late Pleistocene scenario.

Distribution of tropical rainforests in Southeastern Asia has changed over geo-logical time scale, due to movement of tectonic plates and/or global climatic changes. Shorea parvifolia is one of the most common tropical lowland rainforest tree species in Southeastern Asia. To infer population structure and demographic history of S. parvifolia, as indicators of temporal changes in the distribution and extent of tropical rainforest in this region, we studied levels and patterns of nucleotide polymorphism in the following five nuclear gene regions: GapC, GBSSI, PgiC, SBE2, and SODH. Seven populations from peninsular Malaysia, Sumatra, and eastern Borneo were included in the analyses. STRUCTURE analysis revealed that the investigated populations are divided into two groups: Sumatra-Malay and Borneo. Furthermore, each group contained one admixed population. Under isolation with migration model, divergence of the two groups was estimated to occur between late Pliocene (2.6 MYA) and middle Pleistocene (0.7 MYA). The log-likelihood ratio tests of several demographic models strongly supported model with population expansion and low level of migration after divergence of the Sumatra-Malay and Borneo groups. The inferred demographic history of S. parvifolia suggested the presence of a scarcely forested land bridge on the Sunda Shelf during glacial periods in the Pleistocene and predominance of tropical lowland rainforest at least in Sumatra and eastern Borneo. PMID:22957170

The cyclic climate regime of the late Quaternary caused dramatic environmental change at high latitudes. Although these events may have been brief in periodicity from an evolutionary standpoint, multiple episodes of allopatry and divergence have been implicated in rapid radiations of a number of organisms. Shrews of the Sorex cinereus complex have long challenged taxonomists due to similar morphology and parapatric geographic ranges. Here, multi-locus phylogenetic and demographic assessments using a coalescent framework were combined to investigate spatiotemporal evolution of 13 nominal species with a widespread distribution throughout North America and across Beringia into Siberia. For these species, we first test a hypothesis of recent differentiation in response to Pleistocene climate versus more ancient divergence that would coincide with pre-Pleistocene perturbations. We then investigate the processes driving diversification over multiple continents. Our genetic analyses highlight novel diversity within these morphologically conserved mammals and clarify relationships between geographic distribution and evolutionary history. Demography within and among species indicates both regional stability and rapid expansion. Ancestral ecological differentiation coincident with early cladogenesis within the complex enabled alternating and repeated episodes of allopatry and expansion where successive glacial and interglacial phases each promoted divergence. The Sorex cinereus complex constitutes a valuable model for future comparative assessments of evolution in response to cyclic environmental change.

The Irtysh shear zone (ISZ) is an important structure in the framework of the Central Asian Orogenic Belt (CAOB). It represents the site of final collision of Kazakhstan with Siberia during Hercynian times and records up to 1000 km of lateral displacement during subsequent reorganization in the CAOB edifice. We present new zircon U/Pb, apatite fission track and fault kinematic data along the ISZ and consequently derived its tectonic history with emphasis on its formation and reactivation episodes. Carboniferous (˜340-320 Ma) zircon U/Pb ages were obtained for the syn- and post-collisional Kalba-Narym intrusives, dating their emplacement in the framework of the Siberia-Kazakhstan collision. During this period, the ISZ experienced an 'early brittle' left-lateral, mainly transtensional stress regime. Late Carboniferous-Early Permian post-collisional intrusives were emplaced and the stress regime changed to a 'late brittle' regime, characterized by more compressional conditions, indicating rheological strengthening as a response to cessation of ductile shearing and cooling of the ISZ crust.Apatite fission track data and thermal history modeling reveal Late Cretaceous (˜100-70 Ma) cooling of the ISZ basement rocks as a response to denudation of a bordering Late Mesozoic Altai orogen. After this denudation event, the tectonic activity ceased during the Late Mesozoic-Early Cenozoic. A final step of cooling (from ˜25 Ma), exhibited by some of the thermal history models, may reflect reactivation of the ISZ and initiation of Cenozoic Altai mountain building. The Late Plio-Pleistocene phase of mountain building coincides with a new change in the Palaeostress field, characterized by minor transpressional, right-lateral shear conditions.

Coarse, spherule-bearing, elastic units have been discovered at 10 marine sites that span the K/T boundary in northeastern Mexico. We examined one of the best exposed sites in Arroyo el Mimbral, northwest of Tampico. The Mimbral outcrop displays a layered elastic unit up to 3 m thick enclosed by marly limestones of the Mendez (Latest Maastrichian) and Velasco (Earliest Danian) Formations. At its thickest point, this channelized elastic unit is comprised of 3 subunits: (1) a basal, poorly-sorted, ungraded calcareous spherule bed 1 m thick containing relict impact glass and shocked mineral grains, (2) a massive set of laminated calcite-cemented sandstones up to 2 m thick with plant debris at its base, (3) capped by a thin (up to 20 cm) set of rippled sandstone layers separated by silty mudstone drapes containing a small (921 pg/g) iridium anomaly. This tripartite elastic unit is conformably overlain by marls of the Velasco Formation. We also visited the La Lajilla site east of Ciudad Victoria; its stratigraphy is similar to Mimbral's, but its elastic beds are thinner and less extensive laterally. The Mimbral elastic unit has been interpreted previously as being deposited by a megawave or tsunami produced by an asteroid impact on nearby Yucatan (Chicxulub crater). However, a presumed 400-m paleodepth of water at the Mimbral site, channeling of the spherule subunit into the underlying Mendez Formation marls, and the overtopping of the basal, spherule-bearing subunit by the laminated sandstone subunit, all suggest a combined debris flow/turbidite origin for this elastic unit similar to that proposed for Upper Pleistocene sand/silt beds occurring elsewhere in the Gulf of Mexico. In this latter model, the sediment source region for the elastic unit is the lower continental shelf and slope escarpment. For the K/T unit at Mimbral, we propose that thick ejecta blanket deposits composed mostly of spherules were rapidly loaded onto the lower shelf and slope from an impact-generated ejecta curtain.

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 for the region. ?? 2011 Elsevier B.V.

We combine 10Be exposure dating with U-series dating of pedogenic carbonate from subsurface clast-coatings to date deposition of mid-Holocene to late Pleistocene alluvial fans at four sites in the Anza Borrego desert of California. Since each dating technique is subject to distinct assumptions, their systematic uncertainties are largely independent. We therefore consider 10Be and U-series dates that are consistent to be highly reliable. If post-depositional erosion has not significantly modified a fan surface, exposure dates should yield maximum ages when no correction is made for inheritance. U-series dating, in contrast, provides minimum dates because pedogenic carbonate forms after fan deposition. Accordingly, agreement between dates from the two techniques (or lack thereof) provides a ...

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 ...

The present-day seismicity in northeastern Tunisia reported from permanent networks is of low to moderate magnitude. However, earthquakes are mentioned in the literature, specially a destructive one in the antique city of Utique. Geologic, seismic, and neotectonic investigations in this area show that the Utique fold is closely related to the recent tectonic activity in this region. Data show that the Utique fold is built on an east-west fault, and we found evidence of activity of this fault in the past 20 kyr. A seismic section and balanced cross-section show that the slip rate is of the order of 0.38mm.yr^-^1. Our data show definitively the Late Pleistocene-Holocene activity of the Utique Fault; and we can predict the earthquake recurrence interval which should be of ~10^3-10^4 yr. This ...

Grotta di Fumane, a Mousterian site in northern Italy, has been extensively explored over the last two decades in order to gather data on Neanderthal behaviour from during the Late Pleistocene up to the appearance of Modern Humans. The 12 m thick sedimentary sequence includes several layers that have yielded variable amounts of flint artefacts and faunal remains, particularly in BR11, A11, A8-A9 and A5-A6, related to repeated and complex human occupations. The earliest assemblages record the exclusive use of the Levallois method from S9 to BR7 for the production of flakes with unidirectional and centripetal recurrent modalities. In BR9, bifaces and different types of cores have also been found. The first striking technological replacement occurs in BR6, up to BR3, where there is a complex ...

Abstract Pliocene and Pleistocene deposits from Grande-Terre (Guadeloupe archipelago, French Lesser Antilles) provide a remarkable example of an isolated carbonate system built in an active margin setting, with sedimentation controlled by both rapid sea-level changes and tectonic movements. Based on new field, sedimentological and palaeontological analyses, these deposits have been organized into four sedimentary sequences (S1 to S4) separated by three subaerial erosion surfaces (SB0, SB1 and SB2). Sequences S1 and S2 (-Calcaires infrieurs rhodolithes-) deposited during the Late Zanclean to Early Gelasian (planktonic foraminiferal Zones PL2 to PL5) in low subsidence conditions, on a distally steepened ramp dipping eastward. Red algal-rich deposits, which dominate the western part of Grande...

Geomorphic mapping in the upper Conejos River Valley of the San Juan Mountains has shown that three distinct periods of aggradation have occurred since the end of the last glacial maximum (LGM). The first occurred during the Pleistocene-Holocene transition (~12.5-9.5ka) and is interpreted as paraglacial landscape response to deglaciation after the LGM. Evidence of the second period of aggradation is limited but indicates a small pulse of sedimentation at ~5.5ka. A third, more broadly identifiable period of sedimentation occurred in the late Holocene (~2.2-1ka). The latest two periods of aggradation are concurrent with increases in the frequency of climate change in the region suggesting that Holocene alpine and sub-alpine landscapes respond more to rapid changes in climate than to large si...

The shrinkage of the Lisan Lake (LL) to form the recent Dead Sea (DS) was mainly a result of the reduction of the catchment area from around 157,000?km2 during Late Pleistocene to 43,000?km2 presently. The reduction in the catchment area resulted from the eruption and spread of the basalt flows of Jabal Arab-Druz (JAD), which together with the resulting deposition of thick rock debris and gravels occupied the drainage system. The filling of the pre-basalt drainage system, which used to feed the Dead Sea, with basalts and alluvial sediments blocked the inflows from reaching the Dead Sea. Local base levels along the basalt flow boarders such as Azraq Oasis, Sirhan Basin and Damascus Oasis, and numerous pools and mud flats were created.

Most studies of tsunami and seiche related deposits have focussed on coastal and near coastal zones which are most readily accessible, with few investigations of deeper water settings and the potential soft-sediment deformation effects of such waves. The Late Pleistocene Lisan Formation outcropping to the west of the Dead Sea contains superb examples of sedimentary slump folds formed in water depths of <100m. We have collected new structural data from an individual horizon that demonstrate that these gravity-driven slumps may be coaxially refolded and reworked by sheared folds and thrusts verging both back up and then down the palaeoslope. This suggests that it is possible to generate upslope flow of material in some circumstances. A progressive increase in reworking and shearing is develo...

This paper presents stable isotopic results (oxygen and carbon) from both modern and Late Pleistocene-Holocene shells of the land snail Eobania vermiculata (Muller, 1774) from Favignana Island (Sicily). It aims to contribute to the understanding of climate and vegetation history of this region during formation of Upper Palaeolithic, Mesolithic and Meso-Neolithic deposits of Grotta d'Oriente (ORT). Results from both an evaporative model (FBM) and an empirical regional isotopic model (i.e. linear relation between oxygen isotopic composition of shells (@d^1^8Os) and those of local precipitation (@d^1^8Op)) indicate that the @d^1^8Os values of modern specimens are mainly controlled by local temperature, relative humidity and @d^1^8Op at the time of snail activity. Data also suggest that the mo...