WorldWideScience

Sample records for hassanzadeh palaeogeography palaeoclimatology

  1. Southeast Asia's changing palaeogeography

    National Research Council Canada - National Science Library

    Hall, R

    2009-01-01

    Geology provides the basis for understanding distributions of faunas and floras in Southeast Asia but only via a complex interplay of plate movements, palaeogeography, ocean circulation and climate...

  2. Southeast Asia’s changing palaeogeography

    NARCIS (Netherlands)

    Hall, R.

    2009-01-01

    Geology provides the basis for understanding distributions of faunas and floras in Southeast Asia but only via a complex interplay of plate movements, palaeogeography, ocean circulation and climate. Southeast Asia grew incrementally by the addition of continental fragments, mainly rifted from

  3. Lithofacies palaeogeography as a guide to petroleum exploration

    OpenAIRE

    Feng Zengzhao; Bao Hongping; Jia Jinhua; Wang Yigang; Deng Xiuqin

    2013-01-01

    Lithofacies palaeogeography as a guide to petroleum exploration is a very important topic. By using the following five exploration examples, this paper discusses the guide of lithofacies palaeogeography or of sedimentary facies to petroleum exploration. These examples include the dolostone of the Lower Ordovician Majiagou Formation 5 in the Ordos area, the Donghe Sandstone of the Upper Devonian and Lower Carboniferous in the Tarim Basin, the reef of the Upper Permian Changxing Formation in th...

  4. Quaternary stratigraphy and palaeogeography of Poland

    Science.gov (United States)

    Marks, Leszek; Dzierżek, Jan; Janiszewski, Robert; Kaczorowski, Jarosław; Lindner, Leszek; Majecka, Aleksandra; Makos, Michał; Szymanek, Marcin; Tołoczko-Pasek, Anna; Woronko, Barbara

    2016-09-01

    Though the stratigraphical and palaeogeographical framework of the Quaternary in Poland is still to be completed, several crucial points have been confirmed recently. The preglacial series, accepted for years as belonging to the Lower Pleistocene, is undoubtedly of Early Pliocene age, with a huge hiatus above almost until the uppermost Lower Pleistocene. The earliest glaciation in Poland (Nidanian) occurred at about 900 ka BP when the ice sheet reached the mid-southern part of the country. The following Podlasian Interglacial embraced the Brunhes/Matuyama boundary in the middle, in a similar fashion to the corresponding Cromerian Complex in Western Europe. The late Early and early Middle Pleistocene interglacials in Poland comprised 2-3 optima each, whereas every one of the younger interglacials was characterised by a single optimum only. The Late Vistulian ice sheet was most extensive in the western part of Poland (Leszno Phase) whereas the younger Poznań Phase was more extensive in the central and eastern part of the country. This was due to the varied distance from the glaciation center in Scandinavia, making the ice sheet margin reach a terminal position in different times. Palaeoclimatological research in the Tatra Mountains has provided new evidence for the atmospheric circulation over Europe. During cold phases of the Pleistocene in Poland a continental climate extended further westwards, quite the opposite that occurring during warmer intervals.

  5. Lithofacies palaeogeography as a guide to petroleum exploration

    Directory of Open Access Journals (Sweden)

    Feng Zengzhao

    2013-04-01

    Full Text Available Lithofacies palaeogeography as a guide to petroleum exploration is a very important topic. By using the following five exploration examples, this paper discusses the guide of lithofacies palaeogeography or of sedimentary facies to petroleum exploration. These examples include the dolostone of the Lower Ordovician Majiagou Formation 5 in the Ordos area, the Donghe Sandstone of the Upper Devonian and Lower Carboniferous in the Tarim Basin, the reef of the Upper Permian Changxing Formation in the Sichuan Basin, the oolitic bank of the Lower Triassic Feixianguan Formation in the Sichuan Basin, and the lacustrine delta sediments and gravity flow sediments of the Middle and Upper Triassic Yanchang Formation in the Ordos Basin.

  6. The effects of changing solar activity on climate: contributions from palaeoclimatological studies

    Directory of Open Access Journals (Sweden)

    Engels Stefan

    2012-07-01

    Full Text Available Natural climate change currently acts in concert with human-induced changes in the climate system. To disentangle the natural variability in the climate system and the human-induced effects on the global climate, a critical analysis of climate change in the past may offer a better understanding of the processes that drive the global climate system. In this review paper, we present palaeoclimatological evidence for the past influence of solar variability on Earth’s climate, highlighting the effects of solar forcing on a range of timescales. On a decadal timescale, instrumental measurements as well as historical records show the effects of the 11-year Schwabe cycle on climate. The variation in total solar irradiance that is associated with a Schwabe cycle is only ~1 W m−2 between a solar minimum and a maximum, but winter and spring temperatures on the Northern Hemisphere show a response even to this small-scale variability. There is a large body of evidence from palaeoclimatic reconstructions that shows the influence of solar activity on a centennial to millennial timescale. We highlight a period of low solar activity starting at 2800 years before present when Europe experienced a shift to colder and wetter climate conditions. The spatial pattern of climate change that can be recognized in the palaeoclimatological data is in line with the suggested pattern of climate change as simulated by climate models. Millennial-scale climate oscillations can be recognized in sediment records from the Atlantic Ocean as well as in records of lake-level fluctuations in southeastern France. These oscillations coincide with variation in 14C production as recognized in the atmospheric 14C record (which is a proxy-record for solar activity, suggesting that Earth’s climate is sensitive to changes in solar activity on a millennial timescale as well.

  7. Reply to: Terry, J. and Goff, J. comment on “Late Cenozoic sea level and the rise of modern rimmed atolls” by Toomey et al. (2016), Palaeogeography, Palaeoclimatology, Palaeoecology 4 51: 73–83.

    Science.gov (United States)

    Toomey, Michael; Ashton, Andrew; Raymo, Maureen E.; Perron, J. Taylor

    2017-01-01

    We appreciate Terry and Goff's thoughtful comment in response to our proposed atoll development model. Flank collapse of reef-built slopes likely does affect plan-form atoll morphology in some locations and potentially poses a tsunami hazard to low-lying Pacific islands (Terry and Goff, 2013). However, given the often rapid rates of lagoon infill (> 1 mm/yr; Montaggioni, 2005), such failure events would likely need to be frequent and widespread in order to leave a morphologic imprint on modern western Pacific atoll lagoon depths. Few atoll flank collapse features have been dated but many of the arcuate bight-like structures (ABLS) identified could be inherited from scars incised into the initial volcanic edifice (e.g. Terry and Goff, 2013 and refs. therein) — submarine mass wasting has been extensively documented on young hotspot islands (e.g. Hawaiian Islands: Moore et al., 1989; Reunion: Oehler et al., 2008). Atolls in the Marshall Islands, where our main study site Enewetak Atoll is located, are likely ~ 50–100 million years old (Larson et al., 1995) and dating of adjacent deep-water turbidite aprons in the Nauru Basin (DSDP Site 462; Schlanger and Silva, 1986) suggests that large atoll flank collapse events have been relatively infrequent there since the mid-Miocene (vertical accretion, dissolution, and lagoonal infilling) required to accurately simulate Enewetak's ‘recent’ depositional history (8.5–0 Ma) and explain basic differences in lagoon depth among western Pacific atolls.We agree future development of a model incorporating the wider range of processes impacting connectivity between reef-bound lagoons and the ocean (e.g. Ouillon et al., 2004; Toomey et al., 2016b), including stochastic mass wasting events, will be essential for exploring the plan-form and 3D shapes of atolls. To our knowledge, no quantitative model of long-term atoll development has explicitly linked lagoon restriction/sedimentation to episodic flank collapse events (e.g. Montaggioni et al., 2015; Paterson et al., 2006; Quinn, 1991; Warrlich et al., 2002). Testing Terry and Goff's proposed conceptual model for how rim failure processes affect atoll morphology in a numerical context will require deep drilling along arcuate bight-like structures, as well as adjacent, unaffected, rim and lagoon areas, in order quantify how often failures occur and how quickly the rim/lagoon is rebuilt afterwards. The model we present here provides a general framework capable of integrating atoll flank collapse processes once they are sufficiently constrained by such observational datasets.

  8. The role of palaeogeography in the Phanerozoic history of atmospheric CO2 and climate

    Science.gov (United States)

    Goddéris, Yves; Donnadieu, Yannick; Le Hir, Guillaume; Lefebvre, Vincent; Nardin, Elise

    2014-01-01

    The role of the palaeogeography on the geological evolution of the global carbon cycle has been suspected since the development of the first global geochemical models in the early 80s. The palaeogeography has been rapidly recognized as a key factor controlling the long-term evolution of the atmospheric CO2 through its capability of modulating the efficiency of the silicate weathering. First the role of the latitudinal position of the continents has been emphasized: an averaged low latitudinal position promotes the CO2 consumption by silicate weathering, and is theoretically associated to low CO2 periods. With the increase of model complexity and the explicit consideration of the hydrological cycle, the importance of the continentality factor has been recognized: periods of supercontinent assembly coincide with high pCO2 values due to the development of arid conditions which weaken the silicate weathering efficiency. These fundamental feedbacks between climate, carbon cycle and tectonic have been discovered by pioneer modelling studies and opened new views in the understanding of the history of Earth's climate. Today, some of the key features of the Phanerozoic climate can be explained by: (1) continental drift; (2) small continental blocks moving to tropical belts; and (3) modulation of the climate sensitivity to CO2 by palaeogeography changes. Those results emphasize the need for a careful process-based modelling of the water cycle and climate response to the continental drift.

  9. Lithofacies palaeogeography of the Late Permian Wujiaping Age in the Middle and Upper Yangtze Region, China

    Directory of Open Access Journals (Sweden)

    Jin-Xiong Luo

    2014-10-01

    Full Text Available The lithofacies palaeogeography of the Late Permian Wujiaping Age in Middle and Upper Yangtze Region was studied based on petrography and the “single factor analysis and multifactor comprehensive mapping” method. The Upper Permian Wujiaping Stage in the Middle and Upper Yangtze Region is mainly composed of carbonate rocks and clastic rocks, with lesser amounts of siliceous rocks, pyroclastic rocks, volcanic rocks and coal. The rocks can be divided into three types, including clastic rock, clastic rock–limestone and limestone–siliceous rock, and four fundamental ecological types and four fossil assemblages are recognized in the Wujiaping Stage. Based on a petrological and palaeoecological study, six single factors were selected, namely, thickness (m, content (% of marine rocks, content (% of shallow water carbonate rocks, content (% of biograins with limemud, content (% of thin-bedded siliceous rocks and content (% of deep water sedimentary rocks. Six single factors maps of the Wujiaping Stage and one lithofacies palaeogeography map of the Wujiaping Age were composed. Palaeogeographic units from west to east include an eroded area, an alluvial plain, a clastic rock platform, a carbonate rock platform where biocrowds developed, a slope and a basin. In addition, a clastic rock platform exists in the southeast of the study area. Hydrocarbon source rock and reservoir conditions were preliminarily analyzed based on lithofacies palaeogeography. Sedimentary environments have obvious controls over the development of the resource rocks. With regard to the abundance of organic matter, the hydrocarbon potential of the coastal swamp environment is the best, followed by the basin environment and the carbonate rock platform. The gas reservoir types of the Wujiaping Stage can be classified as conventional and unconventional gas reservoirs, like coal bed gas and shale gas; all of them have well exploration prospects.

  10. Mesozoic lithofacies palaeogeography and petroleum prospectivity in North Carnarvon Basin, Australia

    Directory of Open Access Journals (Sweden)

    Tao Chongzhi

    2013-01-01

    Full Text Available The North Carnarvon Basin, which lies in the North West Shelf of Australia, is highly rich in gas resources. As a typical passive marginal basin, it experienced the pre-rifting, early rifting, main rifting, late rifting, post-rifting sagging and passive margin stages. The basin was mainly filled with thick Mesozoic-Cenozoic sediments, of which the Mesozoic hosts the principal source, reservoir and seal intervals. Mesozoic palaeogeography has an important control on the oil and gas distribution. Triassic gas-prone source rocks of deltaic origin determine the high endowment of natural gases in the North Carnarvon Basin. The more restricted distribution of oil accumulations is controlled by oil source rocks in the Upper Jurassic Dingo Claystone. The Muderong Shale deposited in the Early Cretaceous marine transgression provides the effective regional seal for the underlying oil and gas reservoirs.

  11. Palaeomagnetic results from the Early Permian Copacabana Group, southern Peru: Implication for Pangaea palaeogeography

    Science.gov (United States)

    Rakotosolofo, N. A.; Tait, J. A.; Carlotto, V.; Cárdenas, J.

    2006-02-01

    Samples collected from folded carbonate rocks of the Early Permian Copacabana Group exposed in the Peruvian Subandean Zone have been subjected to detailed palaeomagnetic analysis. Thermal demagnetisation of most samples yield stable high unblocking temperature directions dominantly carried by titanomagnetite minerals. This remanence, identified in 32 samples (43 specimens), is exclusively of reverse polarity consistent with the Permian-Carboniferous Reversal Superchron (PCRS). The overall directions pass the fold test at the 99% confidence level and are considered as being a pre-folding remanence acquired in Early Permian times. The Copacabana Group yields an overall mean direction of D = 166°, I = +49° ( α95 = 4.5°, k = 131.5, N = 9 sites) in stratigraphic coordinates and a corresponding palaeosouth pole position situated at λ = 68°S, ϕ = 321°E ( A95 = 5.2°, K = 100). Combining this pole with the coeval high quality data from South America, Africa and Australia results in a mean pole for Gondwana situated at λ = 34.4°S, ϕ = 065.6°E ( A95 = 4.9°, K = 73.6, N = 13 studies) in African coordinates. This pole position supports a Pangaea B palaeogeography in Early Permian times. In contrast, the combined pole for Gondwana diverges from the coeval Laurasian mean pole when assuming the Pangaea A-type configuration. Poor quality of the Gondwana dataset and inclination shallowing in sediments seem to play no role in the misfit between the Permian-Triassic poles from Gondwana and Laurasia in Pangaea A reconstruction.

  12. An evaluation of palaeogeography and palaeoecology in the Most Basin (Czech Republic) and Saxony (Germany) from the late Oligocene to the early Miocene

    Czech Academy of Sciences Publication Activity Database

    Mach, K.; Teodoridis, V.; Matys Grygar, Tomáš; Kvaček, Z.; Suhr, P.; Standke, G.

    2014-01-01

    Roč. 272, č. 1 (2014), s. 13-45 ISSN 0077-7749 R&D Projects: GA ČR(CZ) GAP210/11/1357 Institutional support: RVO:61388980 Keywords : palaeogeography * geochemistry * floras * Most Basin Subject RIV: DD - Geochemistry Impact factor: 0.519, year: 2014

  13. Reconstructing Holocene shore displacement and Stone Age palaeogeography from a foredune sequence on Ruhnu Island, Gulf of Riga, Baltic Sea

    Science.gov (United States)

    Muru, Merle; Rosentau, Alar; Preusser, Frank; Plado, Jüri; Sibul, Ivo; Jõeleht, Argo; Bjursäter, Stefan; Aunap, Raivo; Kriiska, Aivar

    2018-02-01

    Holocene shore displacement and the palaeogeography of Late Mesolithic and Late Neolithic settlements on Ruhnu Island, Gulf of Riga, were reconstructed using foredune sequence luminescence dating, sedimentological data supported by ground-penetrating radar analysis, and GIS-based landscape modelling. The foredune ridges consist of very well to well sorted fine- to medium-grained aeolian sand and are underlain by seaward dipping foreshore sediments. The studied sequence of 38 ridges was formed between 6.91 ± 0.58 ka and 2.54 ± 0.19 ka ago, and represents a period of falling relative sea level. Foredune plain progradation, with average rates of 0.3-0.6 m per year, was controlled by isostatic land uplift, which caused a continuous withdrawal of shorelines to lower elevations. The dated foredune succession was used to reconstruct the coastal palaeogeography of the island. Palaeogeographical reconstructions show that during two phases of Late Mesolithic habitation, at ca. 7.2 cal. ka BP and 6.2 cal. ka BP, seal hunters settled the coastal zone of Ruhnu Island. Based on tool material and pottery type they could have originated from Saaremaa Island, which according to palaeoreconstruction of the Gulf of Riga, was located approximately 70 km northwest of Ruhnu Island during the Late Mesolithic. Later signs of human occupation, radiocarbon dated to ca. 4.7 cal. ka BP, were from the centre of the island, hundreds of metres away from the shore at about 8 m above its contemporary sea level. This Late Neolithic habitation shows a clearly different pattern than earlier coastal settlement, and suggests a shift in subsistence strategy towards agriculture and animal husbandry.

  14. The sedimentary facies characteristics and lithofacies palaeogeography during Middle-Late Cambrian, Sichuan Basin and adjacent area

    Directory of Open Access Journals (Sweden)

    Feifan Lu

    2017-06-01

    Full Text Available Combined with the regional strata filling characteristics of Middle-Upper Cambrian, the present paper conducts a systematic research on sedimentary facies in the basin and its peripheral area by utilizing 164 field outcrops and drilling and coring data. Further, the method of “multi-factor comprehensive synthesis based on single-factor analysis” was employed to investigate the sedimentary facies and palaeogeography of the study area and establish the sedimentary facies model. Stratigraphic reveals that the study area represents the pattern of thin-northwest and thick-southeast by stretching northeast-southwest. Within the present basin, the pattern of “one thin and two thick” predominates, while outside the basin “four thin and three thick” filling feature was found. Sedimentary facies shows that the study area was featured by rimmed carbonate platform. Specifically, carbonate platform, slope and northeastern corner Qinling paleooceanic Basin and southeastern corner Jiangnan Bain was identified from the west to the east. The carbonate platform contains restricted platform, evaporation-restricted platform, semi-restricted platform and the platform margin. Single factor analysis and lithofacies palaeogeographic characteristics manifests that during Middle-Late Cambrian, the western Old land evolved into peneplain stage, and that the eastern and southwestern sub-sags remained connected to the open-sea to some extent. At the time, the shllow seawater circulation was relatively restricted, while the ancient seabed tended to be flat and evaporation characteristics significantly diminished. Secondary sea-level fluctuation intensively influenced the development of scaled grain beach. It is suggested that tide marginal beach, intraplatform shoal subfacies zone, along with Shiqian-SangZhi in southeast and Zhenba-Xinshan in northeast platform-margin beach subfacies zone to be preferable targets for the favorable reservoir facies zone and

  15. Eesti kivimid aitasid lahendada iidse jääaja mõistatust / Tiit Kändler

    Index Scriptorium Estoniae

    Kändler, Tiit, 1948-

    2010-01-01

    Ajakirjas Palaeogeography, Palaeoclimatology, Palaeoecology ilmunud artiklist, milles lahatakse jääaja tekkimise põhjusi. Autorite seas on ka USA Indiana ülikooli teadlane Seth Young ja Dimitri Kaljo TTÜ geoloogia instituudist

  16. On the Measurement of Morphology and Its Change.

    Science.gov (United States)

    1982-03-01

    that transitions within the ceratopsian dinosaurs necessitated overly complex or impossible grid deformations. THETA-RHO ANALYSIS An alternative... Palaeogeography , Palaeo- climatology, Palaeoecology 10:3-11. Benson, R.H. 1976C. Changes in the ostracodes of the Mediterranean with the Messinian salinity...crisis. Palaeogeography , Palaeoclimatology, Palaeoecology 20:147-170. Benson, R.H. 1977. Evolution of Oblitacythereis from Paleocosta (Ostracoda

  17. Palynology and environmental geology

    NARCIS (Netherlands)

    Manten, A.A.

    1967-01-01

    A brief survey of the possibilities and problems of palynology as a contributor to the progress of palaeogeography, palaeoclimatology and palaeoecology is presented. Also shown is how these fields and other branches of the earth sciences which contribute to environmental geology may, in their turn,

  18. Quaternary palaeoceanography and palaeogeography in Northern Denmark

    DEFF Research Database (Denmark)

    Knudsen, Karen Luise; Conradsen, Keld; Heier‐Nielsen, Susanne

    1996-01-01

    the Holocene, including the Pleistocene-Holocene transition. Results from the study of lithology, foraminifera, stable isotope measurements and radiocarbon dates are reviewed while emphasizing the most important contributions to the general understanding of the North Atlantic Quaternary history....

  19. Palaeogeography: Devonian tetrapod from western Europe.

    Science.gov (United States)

    Clément, Gaël; Ahlberg, Per E; Blieck, Alain; Blom, Henning; Clack, Jennifer A; Poty, Edouard; Thorez, Jacques; Janvier, Philippe

    2004-01-29

    Several discoveries of Late Devonian tetrapods (limbed vertebrates) have been made during the past two decades, but each has been confined to one locality. Here we describe a tetrapod jaw of about 365 million years (Myr) old from the Famennian of Belgium, which is the first from western continental Europe. The jaw closely resembles that of Ichthyostega, a Famennian tetrapod hitherto known only from Greenland. The environment of this fossil provides information about the conditions that prevailed just before the virtual disappearance of tetrapods from the fossil record for 20 Myr.

  20. Early Cambrian palaeogeography and the probable Iberia Siberia connection

    Science.gov (United States)

    Gubanov, Alexander P.

    2002-07-01

    The end of the Proterozoic-beginning of the Cambrian is marked by some of the most dramatic events in the history of Earth. The fall of the Ediacaran biota, followed by the Cambrian Explosion of skeletonised bilaterians, a pronounced shift in oceanic and atmospheric chemistry and rapid climatic change from 'snowball earth' to 'greenhouse' conditions all happened within a rather geologically short period of time. These events took place against a background of the rearrangement of the prevailing supercontinent; some authors view this as a sequence of individual supercontinents such as Mesoproterozoic Midgardia, Neoproterozoic Rodinia and Early Cambrian Pannotia. Assembled in the Mesoproterozoic, this supercontinent appears to have existed through the Neoproterozoic into the Early Cambrian with periodic changes in configuration. The final rearrangement took place during the Precambrian-Cambrian transition with the Cadomian and related phases of the Pan-African orogeny. The distribution of Early Cambrian molluscs and other small shelly fossils (SSF) across all continents indicates a close geographic proximity of all major cratonic basins that is consistent with the continued existence of the supercontinent at that time. Subsequently, Rodinia experienced breakup that led to the amalgamation of Gondwana, separation of Laurentia, Baltica, Siberia and some small terranes and the emergence of oceanic basins between them. Spreading oceanic basins caused a gradual geographic isolation of the faunal assemblages that were united during the Vendian-Early Cambrian.

  1. Antarctica, supercontinents and the palaeogeography of the Cambrian 'explosion'

    Science.gov (United States)

    Dalziel, Ian

    2014-05-01

    Laurentia is bordered by latest Precambrian-Cambrian rifted margins and must therefore have been located within a Precambrian supercontinent. Geochronologic and geochemical evidence indicates that it was attached to parts of the East Antarctic craton within the Rodinian supercontinent in the late Mesoproterozoic. The Mawson craton of Antarctica rifted from the proto-Pacific margin of Laurentia during the Neooproterozoic, colliding with the present 'southern cone' of Laurentia at ~600 Ma along the Shackleton Range suture zone as Gondwana and Laurentia amalgamated to form the ephemeral Pannotia supercontinental assembly at the end of the Precambrian. The abrupt appearance of almost all animal phyla in the fossil record is often colloquially referred to as the Cambrian 'explosion' of life on Earth. It is also named 'Darwin's dilemma,' as he appreciated that this seemingly mysterious event posed a major problem for his theory of evolution by natural selection. It coincided with a time of major marine transgression over all the continents. Although the metazoan 'explosion' is now seen as more protracted than formerly recognized, it is still regarded one of the most critical events in the history of the biosphere. One of the most striking aspects of the earliest Cambrian fossils is geographic differentiation. In particular, the first benthic trilobite faunas on Laurentia, ancestral North America, and the newly amalgamated southern supercontinent of Gondwana are distinctly different. This has led to the suggestion of an unknown vicariant event intervening between an ancestral trilobite clade and higher members that are represented in the fossil record, possibly one related to the breakup of a supercontinent. Igneous rocks along the Panthalassic margin of Gondwana, including South America, southernmost Africa and the Ellsworth-Whitmore crustal block of Antarctica, and along the proto-Appalachian margin of Laurentia indicate that final separation of Laurentia from Antarctica occurred just prior to the first appearance of trilobites in the fossil record. This event would have separated the Olenellid trilobite fauna of Laurentia from the Redlichiid fauna of Gondwana by opening a major oceanic connection between the developing Iapetus and pre-existing Pacific ocean basins with profound global environmental effects at the time of the Cambrian 'explosion,' including expansion of continental shelves. The paleogeographic settings of the two great transgressions of the Phanerozoic, the Cambrian and Cretaceous, are remarkably similar. Both seem to have involved comparatively rapid increase in ridge crest length within the ocean basins.

  2. The effects of changing solar activity on climate: contributions from palaeoclimatological studies

    NARCIS (Netherlands)

    Engels, S.; van Geel, B.

    2012-01-01

    Natural climate change currently acts in concert with human-induced changes in the climate system. To disentangle the natural variability in the climate system and the human-induced effects on the global climate, a critical analysis of climate change in the past may offer a better understanding of

  3. Palaeoclimatological perspective on river basin hydrometeorology: case of the Mekong Basin

    Science.gov (United States)

    Räsänen, T. A.; Lehr, C.; Mellin, I.; Ward, P. J.; Kummu, M.

    2013-05-01

    Globally, there have been many extreme weather events in recent decades. A challenge has been to determine whether these extreme weather events have increased in number and intensity compared to the past. This challenge is made more difficult due to the lack of long-term instrumental data, particularly in terms of river discharge, in many regions including Southeast Asia. Thus our main aim in this paper is to develop a river basin scale approach for assessing interannual hydrometeorological and discharge variability on long, palaeological, time scales. For the development of the basin-wide approach, we used the Mekong River basin as a case study area, although the approach is also intended to be applicable to other basins. Firstly, we derived a basin-wide Palmer Drought Severity Index (PDSI) from the Monsoon Asia Drought Atlas (MADA). Secondly, we compared the basin-wide PDSI with measured discharge to validate our approach. Thirdly, we used basin-wide PDSI to analyse the hydrometeorology and discharge of the case study area over the study period of 1300-2005. For the discharge-MADA comparison and hydrometeorological analyses, we used methods such as linear correlations, smoothing, moving window variances, Levene type tests for variances, and wavelet analyses. We found that the developed basin-wide approach based on MADA can be used for assessing long-term average conditions and interannual variability for river basin hydrometeorology and discharge. It provides a tool for studying interannual discharge variability on a palaeological time scale, and therefore the approach contributes to a better understanding of discharge variability during the most recent decades. Our case study revealed that the Mekong has experienced exceptional levels of interannual variability during the post-1950 period, which could not be observed in any other part of the study period. The increased variability was found to be at least partly associated with increased El Niño Southern Oscillation (ENSO) activity.

  4. Palynological records of Gondwana's mid-Permian climate amelioration: New insights from black shale deposits (Collingham Formation, South Africa)

    Science.gov (United States)

    Götz, Annette E.

    2015-04-01

    Permian black shale deposits of the southern Karoo Basin were studied with respect to palynostratigraphy, palaeoenvironment, and palaeoclimate signatures recorded in palynomorph assemblages. The 28 m thick black shales of the Collingham Formation, exposed along road cuttings of the Ecca Pass north of Grahamstown (Eastern Cape Province, South Africa), are rich in sedimentary organic matter with a high content of amorphous organic matter and prasinophytes, characteristic of a deep, stratified marine basin. Moderately preserved pollen grains of the lower part of the formation reveal a mid-Permian (Roadian) age, corresponding to the stratigraphic position of the Collingham Formation in the Namibian part of the Karoo with an absolute age of 270 Ma obtained from a tuff (Stollhofen et al., 2000). The samples from the lower Collingham Formation show a very similar composition as samples from coal seams of the upper Vryheid Formation in the northeastern part of the Karoo Basin. Additionally, a similar stratigraphic trend in changes of palynomorph assemblages was detected, showing a striking increase in taeniate bissacate pollen grains up section. This signature points to a warm-temperate bisaccate-producing plant community in the hinterland, replacing cool-temperate floras of the underlying Whitehill Formation (Ruckwied et al., 2014). The detected palaeoclimate signatures document Gondwana's mid-Permian climate amelioration and have proved to be a powerful tool for high-resolution basin-wide correlation of marine and non-marine successions. References Ruckwied, K., Götz, A.E., Jones, P. 2014. Palynological records of the Permian Ecca Group (South Africa): Utilizing climatic icehouse-greenhouse signals for cross basin correlations. Palaeogeography, Palaeoclimatology, Palaeoecology 413, 167-172. Stollhofen, H., Stanistreet, I.G., Bangert, B., Grill, H. 2000. Tuffs, tectonism and glacially related sea-level changes, Carboniferous-Permian, southern Namibia. Palaeogeography

  5. Lithofacies architecture and palaeogeography of the Late Paleozoic glaciomarine Talchir Formation, Raniganj Basin, India

    Directory of Open Access Journals (Sweden)

    H.N. Bhattacharya

    2015-07-01

    Full Text Available Talchir Formation (Permo–Carboniferous of the Gondwana Supergroup records the Late Paleozoic glaciation in Peninsular India. Talchir sedimentary succession of the Raniganj Basin, Damodar Valley Coalfields, Peninsular India, bears ten facies types grouped under three facies associations, viz., the proglacial conglomerate–sandstone facies association (CS, the foreshore–shoreface conglomerate–sandstone–mudstone facies association (CSM and the prodelta–shelf sandstone–mudstone facies association (SM. Overall facies architecture reflects initial ice–covered terrestrial subglacial sedimentation, which was subsequently reworked and emplaced subaqueously in front of the ice–grounding line, and finally overlapped by storm–laid prodelta–shelf sediments. Repeated glacial advance–retreats with shifts in the position of the ice–grounding line during phases of climatic amelioration led to multiple deglaciation– related fining–up cycles. Decoupled ice sheet and floating icebergs contributed icerafted debris (IRD to these sediments. Gradual retreat of the ice sheet, however, restricted the supply of IRD towards top of the succession. Overlap of wave–agitated shoreface–shelf sediments on the glaciogenic sediments indicates widespread marine transgression caused by glacier melting during ice–house to green–house climatic transition, and crustal downsagging related to glacioisostasy. Subsequently, complete disappearance of the ice sheet caused basinal exhumation along with crustal uplift due to isostatic rebound, leading to multiple horst–graben bounded basinal systems, which received post–Talchir coal–bearing Gondwana sediments.

  6. The Holocene of the Agro Pontino graben : Recent advances in its palaeogeography, palaeoecology, and tephrostratigraphy

    NARCIS (Netherlands)

    Sevink, J.; van der Plicht, J.; Feiken, H.; van Leusen, P. M.; Bakels, C. C.

    2013-01-01

    In the past decade (2000-2010), research within the scope of the 'Hidden Landscapes' project by RUG archaeologists provided important information on the Holocene history of the Agro Pontino graben. This information complemented earlier studies by Dutch Universities (UvA, RUG and UL). The graben was

  7. Reconstructing the Palaeogeographies of a Neolithic - Bronze Age Settlement Mound at Ephesos, Turkey

    Science.gov (United States)

    Ehlers, Lisa; Friederike, Stock; Barbara, Horejs; Helmut, Brückner

    2014-05-01

    Although Ephesos and its surroundings has long been an area of archaeological interest and investigations, the focus has mainly been on sites related to Antiquity and Late Antiquity. Until recently systematic research concerning prehistoric phases of occupation within this region have been lacking. Due to the growing interest in these time periods along the West Anatolian coast, archaeological research projects involving the study of the newly discovered prehistoric settlement mounds located in the vicinity of the prominent ancient city were initiated. The aim of this study was to examine the palaeogeographical and geoarchaeological contexts of the mound (tell), Çukuriçi Höyük, in order to determine the thickness and age of the settlement layers as well as the spatial extent of the tell throughout the different periods of settlement. As additional research to the excavations, 20 sediment cores drilled on and around Çukuriçi Höyük were examined and their physical and geochemical properties as well as existing data were used to reconstruct the palaeoenvironment. The chronostratigraphy relies on AMS-14C ages and findings of diagnostic ceramics; a further attempt was made by luminescence dating. The results reveal that the inhabitants intentionally choose the location due to the beneficial topography, initially, i.e. during Pottery Neolithic times in the early 7th mill. BC, lying upon an elevation within a fertile alluvial plain about 1.5-2 km away from the coast. It seems that during the time of settling (Pottery Neolithic - Early Bronze Age) several rivers flowed in the direct vicinity of the tell. The elevated terrain provided the inhabitants security from the torrents. In addition, the corings reveal that the tell covers an area of about 11,000 m2 and a thickness of settlement layers of c. 8 m. Finally, as a possible result of water management conducted by the inhabitants, sediments related to low-energy depositional conditions are identified at the foot of the tell. With the start of sedentary lifestyles and the beginning of animal domestication, the availability of freshwater became a critical factor. An artificial source - e.g. in the form of a reservoir or cistern - might have provided year-round water availability for the livestock which was especially crucial during the dry and hot summers, typical for this region. The luminescence dating of the cultural layers resulted in an OSL-age of 6,620 ± 750 a, which underlines the early occupation. The measurement of the quartz minerals of the 100-200 μm grain size fraction from the underlying alluvial and colluvial layers indicate malign luminescence properties; an explanation might be the poor mineralogical characteristics of the quartz from this region. A further attempt to measure the final deposition of these layers was conducted with the 4-11 μm grain size fraction resulting in an OSL-age of 44,650 ± 4,460 a.

  8. Palaeogeography of Late Triassic red-beds in Singapore and the Indosinian Orogeny

    Science.gov (United States)

    Oliver, Grahame; Prave, Anthony

    2013-10-01

    A red-bed facies of the Upper Triassic Jurong Formation has been logged on Sentosa Island, Singapore. An overall coarsening and thickening-upward pattern is well developed. The lower part of the section is dominated by purple-red, massive to finely laminated illite-smectite-kaolin-rich mudstones containing thin, discontinuous lenses of fine sandstone marked by low-angle lamination and small ripples. One dinosaur-like foot print has been discovered in a loose block of red mudstone. It is concluded that this is a lacustrine sequence and it is proposed to name the lake, Lake Sentosa. The upper part of the sequence consists of flat-laminated to trough cross-bedded medium-grained sandstone and granule to cobble conglomerates alternating with purple-red mudstone. The mudstone-sandstone packages are arranged in decametre-scale coarsening-upward cycles. The channelling and decimetre-scale cross-bedding characterising the sandstone and conglomeratic beds is evidence for deposition by flashy fluvial flood processes, possibly feeding into the lake as a fresh water delta. One possible dinosaur trackway in granule size conglomerate has been located. Detrital zircon U-Pb ages vary from 2.7 Ba to 209 Ma with significant populations at ˜245 Ma and 220 Ma. These ages throw light on the timing of the Indosinian Orogeny. The molasse red-beds of the Jurong Formation were deposited in a half graben formed in the hangingwall of the Bukit Timah Fault when central Peninsular Malaysia went into extension following the climax of the Indosinian Orogeny in the Late Triassic.

  9. Earth at 200 Ma: Global palaeogeography refined from CAMP palaeomagnetic data

    Science.gov (United States)

    Ruiz-Martínez, Vicente Carlos; Torsvik, Trond H.; van Hinsbergen, Douwe J. J.; Gaina, Carmen

    2012-05-01

    The Central Atlantic Magmatic Province was formed approximately 200 Ma ago as a prelude to the breakup of Pangea, and may have been a cause of the Triassic-Jurassic mass extinction. Based on a combination of (i) a new palaeomagnetic pole from the CAMP related Argana lavas (Moroccan Meseta Block), (ii) a global compilation of 190-210 Ma poles, and (iii) a re-evaluation of relative fits between NW Africa, the Moroccan Meseta Block and Iberia, we calculate a new global 200 Ma pole (latitude = 70.1° S, longitude = 56.7° E and A95 = 2.7°; N = 40 poles; NW Africa co-ordinates). We consider the palaeomagnetic database to be robust at 200 ± 10 Ma, which allows us to craft precise reconstructions near the Triassic-Jurassic boundary: at this very important time in Earth history, Pangea was near-equatorially centered, the western sector was dominated by plate convergence and subduction, while in the eastern sector, the Palaeotethys oceanic domain was almost consumed because of a widening Neothethys. We show that there has been negligible net displacement of the Moroccan Meseta relative to Africa since 200 Ma. We calculate a new fit between Iberia and NW Africa, showing that models inferring minor Cretaceous rotation and major Cretaceous sinistral translation of Iberia relative to Europe are inconsistent with palaeomagnetic Iberia-Africa fits at 200 Ma. During Pangea breakup (~ 195 Ma, opening of the Central Atlantic), and shortly after the CAMP outburst, Laurasia rotated clockwise relative to Gondwana around an Euler pole located in SE Iberia. The CAMP and its likely contribution to climate change, mass extinction and Pangea breakup profoundly changed planet Earth and we show that CAMP was sourced by a deep mantle plume that started its disturbing journey from the core-mantle boundary.

  10. Pleistocene PaleoDEMs for GIA modelling and ice age palaeogeography of the North Sea Basin

    Science.gov (United States)

    Busschers, Freek; Cohen, Kim

    2017-04-01

    An important input for modelling coastline shifting over ice age periods with sea-level fall and rise, is palaeotopography. Palaeotopography, however, is difficult information to acquire and usually sophisticated geophysical glacio-isostatic adjustment (GIA) models are run over just the modern bathymetry. We present a set of palaeoDEMs for the last two glacial Terminations (c. 130 resp. c. 15 ka) for the southern North Sea Basin (onshore and offshore parts; Netherlands, Belgium and British surroundings), including a warping DEM to correct for long-term 'background' subsidence. The palaeoDEMs are constructed using techniques developed for high resolution geomodelling by TNO Geological Survey of the Netherlands, using borehole data and surface bathymetry/topography grids and scripting that honours lithostratigraphical order. The warping DEMs make use of the thickness mapping at Quaternary and Neogene time scales. Together, these sets can be used to patch the modern bathymetry and ice-thickness DEMs that are currently used in GIA modelling.

  11. Lithofacies palaeogeography of the Carboniferous and Permian in the Qinshui Basin, Shanxi Province, China

    Directory of Open Access Journals (Sweden)

    Long-Yi Shao

    2015-10-01

    The Xiashihezi, Shangshihezi, and Shiqianfeng Formations consist mainly of red mudstones with thick-interbedded sandstones. During the deposition of these formations, most areas of the basin were occupied by a fluvial channel, resulting in palaeogeographic units that include fluvial channel zones and flood basins. The fluvial channel deposits consist mainly of relatively-thick sandstones, which could have potential for exploration of tight sandstone gas.

  12. Late Ordovician palaeogeography and the positions of the Kazakh terranes through analysis of their brachiopod faunas

    Science.gov (United States)

    Popov, Leonid E.; Cocks, Robin M.

    2017-09-01

    Detailed biogeographical and biofacies analyses of the Late Ordovician brachiopod faunas with 160 genera, grouped into 94 faunas from individual lithotectonic units within the Kazakh Orogen strongly support an archipelago model for that time in that area. The Kazakh island arcs and microcontinents within several separate clusters were located in the tropics on both sides of the Equator. Key units, from which the Late Ordovician faunas are now well known, include the Boshchekul, Chingiz-Tarbagatai, and Chu-Ili terranes. The development of brachiopod biogeography within the nearly ten million year time span of the Late Ordovician from about 458 to 443 Ma (Sandbian, Katian, and Hirnantian), is supported by much new data, including our revised identifications from the Kazakh Orogen and elsewhere. The Kazakh archipelago was west of the Australasian segment of the Gondwana Supercontinent, and relatively near the Tarim, South China and North China continents, apart from the Atashu-Zhamshi Microcontinent, which probably occupied a relatively isolated position on the south-western margin of the archipelago. Distinct faunal signatures indicate that the Kazakh terranes were far away from Baltica and Siberia throughout the Ordovician. Although some earlier terranes had joined each other before the Middle Ordovician, the amalgamation of Kazakh terranes into the single continent of Kazakhstania by the end of the Ordovician is very unlikely. The Late Ordovician brachiopods from the other continents are also compared with the Kazakh faunas and global provincialisation statistically determined.

  13. Palaeogeography and evolution of the Dubičiai glaciolacustrine basin in southern Lithuania

    Directory of Open Access Journals (Sweden)

    Švedas, Kęstutis

    2010-06-01

    Full Text Available The Dubičiai glaciolacustrine basin was studied by means of geomorphological, lithological and cartographic methods in order to reconstruct water level changes during postglacial time. The formation of the basin and respective sedimentation processes began immediately after the deglaciation. Glaciolacustrine terraces in the Dubičiai basin formed during the Frankfurt (Grūda Stage of the last glaciation, and during the Dryas–Allerød, Boreal and Subatlantic chronozones. Intense evolution of the basin took place at the end of the Late Pleistocene and in the Early Holocene. The greatest changes in the topography were due to thermokarst processes which began in the Allerød and continued until the Boreal. Climate became warm and moist at the beginning of the Preboreal and thus created good conditions for accumulation of gyttja, peat and freshwater lime. The latest stage in the development of the Dubičiai basin occurred in the 19th century. In 50 years the area of the basin decreased by 10 times: from 221 ha in 1850 to 20 ha in 1900. The last major change in the hydrographic network of the basin occurred in 1958–59 when an artificial drainage project was completed.

  14. Calcareous nannofossil events in the pre-evaporitic Messinian

    Science.gov (United States)

    Negri, Alessandra; Lozar, Francesca

    2017-04-01

    During the Messinian (7.2 to 5.3 Ma) the Mediterranean area experienced fast and deep climatic and eustatic structural changes. The stratigraphic framework for this interval is relatively well constrained and the beginning of the Messinian salinity crisis dated at 5.97 Ma determine a duration of at least 1.2 Ma for the pre-evaporitic Messinian that is object of this study. Several sites (Faneromeni, Pissouri, Polemi Fanantello borehole, Lemme, Pollenzo, Govone, Moncalvo; Wade and Bown, 2006; Kouwenhoven et al 2006, Morigi et al 2007, Lozar et al 2010, Dela Pierre et al 2011) show similar calcareous nannofossil record behavior, with several Sphenolithus spp. peaks recognised at different quotes in each of the sections. Aim of the present work is to compare the calcareous nannofossil data achieved in the above mentioned sections: interestingly, the occurrence of strongly oligotypic assemblages related to high salinity and unstable environments, appear to correlate precisely among the investigated sites and occur immediately before the onset of the Messinian salinity crisis, then offering the possibility to use them as bioevents for regional correlation. References Dela Pierre, F., Bernardi, E., Cavagna, S., Clari, P., Gennari, R., Irace, A., Lozar, F., Lugli, S., Manzi, V., Natalicchio, M., Roveri, M., Violanti, D., 2011. The record of the Messinian salinity crisis in the Tertiary Piedmont Basin (NW Italy): The Alba section revisited. Palaeogeography, Palaeoclimatology, Palaeoecology 310, 238-255. Kouwenhoven, T.J., Morigi, C., Negri, A., Giunta, S., Krijgsman, W., Rouchy, J.M., 2006 Paleoenvironmental evolution of the eastern Mediterranean during the Messinian: Constraints from integrated microfossil data of the Pissouri Basin (Cyprus). Marine Micropaleontology 60, 17-44. Lozar, F., Violanti, D., Dela Pierre, F., Bernardi, E., Cavagna, S., Clari, P., Irace, A., Martinetto, E., Trenkwalder, S., 2010. Calcareous nannofossils and foraminifers herald the Messinian

  15. Palaeogeography and palaeoecology of early Floian (Early Ordovician cephalopods from the Upper Fezouata Formation, Anti-Atlas, Morocco

    Directory of Open Access Journals (Sweden)

    B. Kröger

    2012-08-01

    Full Text Available In the central Anti-Atlas (Morocco, the Early Ordovician succession consists of about 1000 m of fossiliferous argillites and siltstones. The Upper Fezouata Formation (Floian contains a comparatively rich and abundant cephalopod association. A small collection of these cephalopods is described herein for the first time. The cephalopods are interpreted as autochthonous or parautochthonous, representing a fauna, which originally lived nektobenthically in the open water above the sediments or related to the sea bottom. The cephalopod associations of the Upper Fezouata Formation are similar to other contemporaneous assemblages known from higher palaeolatitudes and associated with deeper depositional settings and in siliciclastically dominated deposits. They are composed almost exclusively of slender orthocones, in this case predominantly of Destombesiceras zagorense n. gen., n. sp., which is interpreted as an early discosorid. Bathmoceras australe Teichert, 1939 and Bathmoceras taichoutense n. sp. from the Upper Fezouata Formation are at present the earliest unambiguous occurrences of bathmocerid cephalopods. Epizoans on the shell of a specimen of Rioceras are the earliest evidence of bryozoans growing as potential hitchhikers on cephalopod shells, indicating an early exploitation of a pseudoplanktonic lifestyle in this phylum. doi:10.1002/mmng.201200004

  16. Lithofacies palaeogeography and biostratigraphy of the lowermost horizons of the Middle Triassic Hallstatt Limestones (Argolis Peninsula, Greece

    Directory of Open Access Journals (Sweden)

    Fotini A. Pomoni

    2013-07-01

    Taking into consideration the present location of the Hallstatt Formation, in the context of the Hellenides, an area suitable for the deposition of the Hallstatt Limestones, should be located between the sub-Pelagonian (western part of the Pelagonian zone and Pindos geotectonic zones, which during the Triassic corresponded to a platform slope and a deep ocean, respectively. The widespread Middle Triassic Han Bulog Limestones (ammonoid-bearing pelagic limestones from Triassic successions of the Eastern Alps (Dinarides, Hellenides may have formed partly in similar slope environments.

  17. PaleoGeo: a Web based GIS database for paleoenvironmental studies

    Science.gov (United States)

    Song, Wonsuh; Kondo, Yasuhisa; Oguchi, Takashi

    2014-05-01

    Paleoenvironmental studies cover various fields such as paleohydrology, geomorphology, paleooceanology, paleobiology, paleoclimatology, and chronology. It is difficult for an individual researcher to collect and compile enormous data regarding these fields. We have been compiling portal data and presenting them using a web-based geographical information system (Web-GIS) called PaleoGeo for the multidisciplinary project 'Replacement of Neanderthals by Modern Humans'. The aim of the project is to reconstruct the distribution of Neanderthals and modern humans in time and space in relation to past climate change. We have been collecting information from almost three thousand articles of 13 journals regarding paleoenvironmental research (i.e., Boreas, Catena, Climatic Change, Earth Surface Processes and Landforms, Geomorphology, Journal of Quaternary Science, Palaeogeography, Palaeoclimatology, and Palaeoecology, Quaternary International, Quaternary Research, Quaternary Science Reviews, The Holocene, and The Journal of Geology). The topics of the articles were classified into six themes (paleohydrology, earth surface processes and materials, paleooceanology, paleobiology, palaeoclimatology, and chronology) and 19 subthemes (hydrology, flood, fluvial, glacier, fluvial/glacier, sedimentology, soil, slope process, periglacial, peat land, eolian, sea-level, biology, vegetation, zoology, vegetation/zoology, archaeology, climate, atmosphere, and chronology). The collected data consist of the journal name, information about each paper (authors, title, volume, year, and page numbers), site location (country name, longitude, and latitude), theme, subtheme, keywords, DOI (Digital Object Identifier), and period (era). Location data are indispensable for paleoenvironmental studies. The PaleoGeo shows information with a map, which is an advantage of this database system. However, the number of the paleoenvironmental studies is growing rapidly and we have to effectively cover them as

  18. Multi-species coral Sr/Ca based sea-surface temperature reconstruction data using Orbicella faveolata and Siderastrea siderea from Dry Tortugas National Park, Florida

    Science.gov (United States)

    Flannery, Jennifer A.; Richey, Julie N.; Thirumalai, Kaustubh; Poore, Richard Z.; Delong, Kristine

    2016-01-01

    New sub annual and mean annual Sr/Ca records from two species of massive coral, Orbicella faveolata (coral B3) and Siderastrea siderea (coral CG2), from the Dry Tortugas National Park, FL (DRTO). Both corals have well-constrained chronologies, with coral B3 ranging from 1893-2008 and coral CG2 ranging from 1837-2012. We combine these new records with published Sr/Ca data from three additional S. siderea coral colonies (DeLong et al., 2014) to generate a 278-year-long multi-species composite Sr/Ca-SST record from DRTO. This new record from a region sensitive to the Atlantic Multidecadal Oscillation (AMO) and Atlantic Meridional Overturning Circulation (AMOC) variations provides insight into the link between the two systems. Also included are new annual linear extension rates for each species. The coral samples and derived data were collected under the National Park Service Scientific Research and Collecting permits DRTO-2008-SCI-0015 and DRT0-2012-SCI-0001; accession numbers DRTO-241 and DRTO-353. For further information regarding data collection and/or processing methods refer to Flannery, J. A., J. N. Richey, K. Thirumalai, R. Z. Poore, and K. L. DeLong, 2016, Multi-species coral Sr/Ca based sea-surface temperature reconstruction using Orbicella faveolata and Siderastrea siderea from the Florida Straits, Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, http://dx.doi.org/10.1016/j.palaeo.2016.10.022.

  19. Environmental change during the Late Berriasian - Early Valanginian: a prelude to the late Early Valanginian carbon-isotope event?

    Science.gov (United States)

    Morales, Chloé; Schnyder, Johann; Spangenberg, Jorge; Adatte, Thierry; Westermann, Stephane; Föllmi, Karl

    2010-05-01

    European basins show that the climate became more humid during the Late Berriasian (Hallam et al., 1991, Schnyder et al., 2009). The aim of this project is to precisely characterize and date paleoenvironmental and paleoclimatic change during the latest Berriasian-Early Valanginian time interval in order to decipher if they can be viewed as precursor events, linked with the late Early Valanginian δ13C event. Three key sections have been studied: Capriolo (N Italy), Montclus (SE France) and Musfallen (E Switzerland) located in the Lombardian and Vocontian basins and on the Helvetic platform, respectively. Phosphorus and stable-isotope analyses have been performed, in addition to clay-mineralogy and facies determinations. The three sections show similar and comparable trends: The phosphorus content (in ppm) is higher in Late Berriasian sediments (compared to Early Berriasian and Valanginian deposits) and this period is also characterised by a decrease in δ13C values. This is interpreted as the result of enhanced continental weathering, which would be coeval with a change to a more humid climate during the Late Berriasian (Schnyder et al., 2009). References: Bornemann, A. and Mutterlose, J. (2008). "Calcareous nannofossil and d13C records from the Early Cretaceous of the Western Atlantic ocean: evidence of enhanced fertilization accross the Berriasian-Valanginian transition." palaios 23: 821-832. Duchamp-Alphonse, S., Gardin, S., Fiet, N., Bartolini, A., Blamart, D. and Pagel, M. (2007). "Fertilization of the northwestern Tethys (Vocontian basin, SE France) during the Valanginian carbon isotope perturbation: Evidence from calcareous nannofossils and trace element data." Palaeogeography, Palaeoclimatology, Palaeoecology 243(1-2): 132-151. Föllmi, K.B., Weissert, H., Bisping, M. & Funk, H. 1994: Phosphogenesis, carbon-isotope stratigraphy, and carbonate-platform evolution along the Lower Cretaceous northern tethyan margin. Geological Society of America, Bulletin 106, 729

  20. Storms and tsunamis: evidence of event sedimentation in the Late Jurassic Tendaguru Beds of southeastern Tanzania

    Science.gov (United States)

    Bussert, Robert; Aberhan, Martin

    2004-06-01

    In Late Jurassic shallow marine siliciclastic sediments of the dinosaur-bearing Tendaguru Beds from the Mandawa Basin of southeastern Tanzania we identified several event deposits. Based on an analysis of their sedimentological and palaeontological features, a storm-induced origin can be assumed for the majority of these deposits. This interpretation is in agreement with the regional palaeogeography and palaeoclimatological data, and is further supported by the widespread evidence of Late Jurassic storm-controlled sedimentation in adjacent basins along the East African margin. A particularly striking feature is a laterally extensive, conglomeratic bed with gravel components up to 30 cm in diameter, and megaripples indicating southward transport directions. The troughs between ripples are filled by cross-bedded fine-grained sandstones and siltsones with inferred transport directions to the north. Giant bedforms, a mixture of clasts of marine and continental origin, and evidence of opposite current directions suggest that this chaotically deposited sediment may have formed from a tsunami. Within the available time resolution this event is synchronous with the Morokweng impact structure in South Africa. However, because of the considerable distance of Morokweng from the Jurassic sea, direct links between both events cannot be established. Alternative mechanisms such as a landslide-generated tsunami are plausible, but not yet supported by geophysical data.

  1. Diapiric uplift of an MIS 3 marine deposit in SW Spain: Implications for Late Pleistocene sea level reconstruction and palaeogeography of the Strait of Gibraltar

    Science.gov (United States)

    Gracia, F. J.; Rodríguez-Vidal, J.; Cáceres, L. M.; Belluomini, G.; Benavente, J.; Alonso, C.

    2008-11-01

    In the Bay of Cádiz (SW Spain) an Upper Pleistocene beach deposit (31.5 ka BP) has been recognised at about 1-3 m above m.s.l. The deposit is affected by a set of joints and fractures filled by calcretes and other subaerial sediments, dated at 19.9 ka BP. Deformation and uplift of this level is related to the moderate activity of a diapiric structure. The resulting uplift produced local emersion of the deposit and a transition from marine to continental conditions during the Late Quaternary. The deformational style and tectonic location of the deposit argue against strong vertical motion. Regional comparisons between this diapir and other similar and coeval structures near the zone suggest a vertical uplift of about 25 m. Therefore, between 30 and 20 ka BP the sea level can be supposed to have been placed near to its present-day position, probably less than 30 m below. These results confirm other regional data indicating that during MIS 3 several relative sea level rises took place, reaching heights of only several tens of metres below the present m.s.l. The palaeogeographical implications of these results include the existing controversy about the possible crossing of the Strait of Gibraltar by Neanderthals between ca 40 and 30 ka. The palaeogeographical reconstruction of the Strait for this period suggests that its width and depth were very similar to the present ones.

  2. Sedimentary architecture and palaeogeography of lower Slochteren Aeolian cycles from the Rotliegend desert-lake margin (Permian), the Markham area, Southern North Sea

    NARCIS (Netherlands)

    Belt, F.J.G. van den; Hulten, F.F.N. van

    2011-01-01

    The Rotliegend gas play in the Southern Permian Basin has yielded over 200 gas fields in the Netherlands; they are found in an E-W fairway along the southern flank of the basin. Sandstones generally pinch out basinward, but localized, isolated sands are present north of the main fairway. The

  3. Palaeogeography and relative sea-level history forcing eco-sedimentary contexts in Late Jurassic epicontinental shelves (Prebetic Zone, Betic Cordillera): An ecostratigraphic approach

    Science.gov (United States)

    Olóriz, Federico; Reolid, Matías; Rodríguez-Tovar, Francisco J.

    2012-02-01

    The analysis of macroinvertebrate and foraminiferal assemblages from Upper Jurassic (Middle Oxfordian to Lower Kimmeridgian) epicontinental shelf deposits in the Prebetic (Betic Cordillera, southern Spain) reveals the influence of environmental changes. They are expressed as selected parameters in palaeogeographic and stratigraphic trends (litho- and microfacies, faunal composition, taphonomy), which are interpreted in the context of relative sea-level histories. Middle Oxfordian to early Kimmeridgian (Transversarium to Planula Chrones) rocks and faunal assemblages in comparatively distal sectors (distal shelf) show lower sedimentation rates (lumpy lithofacies), and higher proportions of ammonoids, planktic foraminifera, corrasion degree, microboring and encrustation. Landwards, towards the mid-shelf, eco-sedimentary conditions resulted in spongiolithic limestones and marl-limestone rhythmites with local development of microbial-sponge buildups. Greater distance from shore during relative sea-level highs accords with greater: (1) stratigraphic condensation; (2) abundance in ammonoids, planktic foraminifera and nubeculariids; and (3) degrees of corrasion, microboring and encrustation. These trends in faunal composition and taphonomy agree with backstepping phases, increasing ecospace and a longer exposition of shelly remains on the sea bottom. Decreasing distance from shore during relative sea-level lows relates to opposite trends, as evidenced by: (4) increasing terrigenous input and decreasing stratigraphic condensation; (5) impoverishment in ammonoids and planktic foraminifera; and (6) diminution of corrasion, microboring and encrustation. Phases of forestepping/progradation and aggradation, a reduction of ecospace for nekto-planktic organisms, and comparatively rapid burial of shell remains are interpreted to force the recorded trends. An ecostratigraphic approach is used here to correlate and characterise sea-level changes, applying high resolution stratigraphy to sections where the identification of relevant surfaces is more difficult. The changes in distance from shore and ecospace, triggered by relative sea-level fluctuations, are considered prime factors forcing trade-offs in faunal communities of the studied fossil assemblages. Ecostratigraphy was used as a template for the characterization, correlation and interpretation of relative sea-levels and associated sedimentary packages in a time span from just above the Milankovitch band to the million-year scale.

  4. A possible bridge between Adria and Africa: New palaeobiogeographic and stratigraphic constraints on the Mesozoic palaeogeography of the Central Mediterranean area

    Science.gov (United States)

    Zarcone, Giuseppe; Petti, Fabio M.; Cillari, Azzurra; Di Stefano, Pietro; Guzzetta, Dario; Nicosia, Umberto

    2010-12-01

    Dinosaur records in central and southern Italy testify to the occurrence of a diverse dinosaur fauna on the Apennine and Apulian carbonate platforms at least from the Tithonian to the Santonian. Most of the palaeogeographic reconstructions show these domains as topographically isolated areas, separated by deep pelagic basins and far from emerged continental areas. Thus, they hardly justify the long-lasting occurrence of these terrestrial vertebrates. Recent studies on the Mesozoic Panormide Carbonate Platform (western Sicily) yielded important stratigraphical and palaeontological data, which provide evidence for a convincing explanation of this unresolved problem. The recent discovery of a theropod bone in mid-Cretaceous peritidal levels of the Panormide Platform as well as the anomalous subsidence of this palaeogeographic domain, strongly support the existence of a crustal sector (filtering bridge) which connected Africa to Adria.

  5. Continental Supply and Climate Variations In Mediterranean Pliocene

    Science.gov (United States)

    Foucault, Alain; Melieres, Frederic; Combourieu-Nebaout, Nathalie

    From the Pliocene period to present day, the Mediterranean marine sedimentation is characterised by cycles resulting from climate variations, which are controlled by Earth orbital parameters. Theses cycles are evidenced in the sediment content vari- ation, particularly through composition and proportions of the material supplied by continents. Concerning mineral supply we were able to show alternations of humid pe- riods, during which fluvial supply is dominant, and arid periods, during which eolian supply from the southern borderlands of the Mediterranean is significant. Concerning organic supply, palynological study confirms theses climatic controls, emphasising the importance of fresh water runoff during humid periods. This synthetic image re- sults from the study of several Pliocene Mediterranean stratigraphical series located in Sicily (Lido Rosselo, Punta di Maiata, Punta Piccola), Calabria (Monte Singa, Vrica) or cored during Leg 160 ODP (Hole 964). References: FOUCAULT A. et MELIERES F. (1995).- Nature et origine des cy- cles sédimentaires métriques du Pliocène de l'Ouest méditerranéen d'après l'étude du contenu terrigène de la Formation Narbone (Punta Piccola, Sicile, Italie). C. R Ac. Sci. Paris, t. 321, II a, p. 869-876. MELIERES F., FOUCAULT A. and BLANC-VALLERON, M.M. (1998). Mineralogical record of cyclic climate changes in Mediterranean Mid-Pliocene deposits from Hole 964A (Ionian Basin) and from Punta Piccola (Sicily). In Robertson, A.H.F., Emeis, K.-C., Richter, C., and Camer- lenghi, A. (Eds.), 1998. Proc. ODP., Sci. Results, 160; College Station, TX (Ocean Drilling Program), p. 219-226. FOUCAULT, A. and MELIERES, F. (2000). Palaeocli- mate cyclicity in central Mediterranean Pliocene sediments: the mineralogical signal. Palaeogeography, Palaeoclimatology, Palaeoecology, 148: 311-323.

  6. Cretaceous magmatism in the High Canadian Arctic: Implications for the nature and age of Alpha Ridge

    Science.gov (United States)

    Bono, Richard; Tarduno, John; Singer, Brad

    2013-04-01

    Cretaceous magmatism in the High Arctic, best expressed on Axel Heiberg and Ellesmere Island, can provide clues to the nature and age of the adjacent Alpha Ridge, which is in turn a key to understanding the tectonic evolution of the Arctic Ocean. Although the incorporation of some continental crust cannot be excluded, the prevailing view is that Alpha Ridge is dominantly thickened oceanic crust, analogous to oceanic plateaus of the Pacific and Indian Ocean. Together with the on-land volcanic exposures, Alpha Ridge composes the High Arctic Large Igneous Province (LIP), but the physical processes responsible for the magmatism remain unclear. Here we focus on two volcanic formations found on the Canadian Arctic margin. The Strand Fiord Formation is composed of a series of classic continental flood basalt flows, and represents the most voluminous expression of volcanism that has survived erosion. These basalts yield a 40Ar/39Ar age of ~95 Ma (Tarduno et al., Science, 1998) but this comes from the distant edge of the flood basalt exposures. The Hansen Point Volcanics consist of felsic and mafic rocks; previous age assignments range from the Maastrichtian (on the basis of palynomorphs, Falcon-Lang et al., Palaeogeography, Palaeoclimatology, Palaeoecology, 2004) to 80 Ma (Rb/Sr isochron, Estrada and Henjes-Kunst, Z. dt. Geol. Ges, 2004). Here we report new 40Ar/39Ar radioisotopic and paleomagnetic data from the Hansen Point Volcanics. In contrast to the latest Cretaceous/Paleogene dates, we find ages of ~95 Ma and 88-90 Ma. Because of the proximity of the landward extension of Alpha Ridge to Hansen Point, these new ages suggest that volcanism that contributed to the construction of Alpha Ridge may have extended over at least a 7 million interval (although it could have occurred in pulses). We will discuss the implications of these new data for candidate mantle processes that could have been responsible for the emplacement of Alpha Ridge and the High Arctic LIP.

  7. Comments on ;Geochronology and geochemistry of rhyolites from Hormuz Island, southern Iran: A new Cadomian arc magmatism in the Hormuz Formationˮ by N. S. Faramarzi, S. Amini, A. K. Schmitt, J. Hassanzadeh, G. Borg, K. McKeegan, S. M. H. Razavi, S. M. Mortazavi, Lithos, Sep. 2015, V.236-237, P.203-211: A missing link of Ediacaran A-type rhyolitic volcanism associated with glaciogenic banded iron salt formation (BISF)

    Science.gov (United States)

    Atapour, Habibeh; Aftabi, Alijan

    2017-07-01

    A critical overview on the petrogeochemistry of Hormuz Island highlights that the Ediacaran Hormuz Complex includes synchronous felsic submarine volcanism associated with diamictite and dropstone-bearing banded iron salt (anhydrite, halite, sylvite) formation (BISF) that formed 558-541 Ma in the Late Neoproterozoic. Our field observations disagree with Faramarzi et al. (2015) on the geological map of the Hormuz Island, in particular on the occurrence of the ferruginous agglomerates in the Hormuz Island, thus the geological data do not provide a robust geological mapping. The agglomerates are commonly related to the strombolian peralkaline basaltic eruptions rather than the submarine felsic volcanism. Based on the tectonogeochemical diagrams extracted from the geochemical data of the authors, the Hormuz rhyolites show an affinity to the A-type or A2-type submarine riftogenic and or intra-plate rhyolites of Eby (1992). However, the authors admitted two sides of the debate and proposed an extensional back arc or rift-related magmatic activity as well as continental arc margin setting. The rhyolites are also similar to the Ediacaran Arabian-Nubian A-type alkaline rhyolites that formed by intra-plate rifting during the Pan-African orogen in the proto-Tethys shallow grabens of the Gondwana supercontinent. The most exceptional feature of the Hormuz rhyolites is related to their co-occurrence with the Ediacaran salt rocks, glaciogenic diamictites and jaspillitic banded iron formations, which have never ever been reported previously.

  8. Anxiety, Self-Efficacy, and College Exam Grades

    Science.gov (United States)

    Barrows, Jennifer; Dunn, Samantha; Lloyd, Carrie A.

    2013-01-01

    A student's level of self-efficacy and test anxiety directly impacts their academic success (Abdi, Bageri, Shoghi, Goodarzi, & Hosseinzadeh, 2012; Hassanzadeh, Ebrahimi, & Mahdinejad, 2012). When a student doubts themself and their own ability to test well, the students' sole focus becomes worrying about poor grades and cannot focus on…

  9. Foraminifera and the ecology of sea grass communities since the late Cretaceous

    Science.gov (United States)

    Hart, Malcolm; Smart, Christopher; Jagt, John

    2016-04-01

    large as such a change in water depth would have been disastrous to such a fragile ecosystem. The fossil record of sea grasses in the Cenozoic is relatively limited, though there are some assemblages of benthic foraminifera that are suggestive of their presence, despite the lack of plant fossils. Hart, M.B., FitzPatrick, M.E.J. & Smart, C.W. 2016. The Cretaceous/Paleogene boundary: Foraminifera, sea grasses, sea level change and sequence stratigraphy. Palaeogeography, Palaeoclimatology, Palaeoecology, 441, 420-429.

  10. Geomicrobiology and hopanoid content of sulfidic subsurface vent biofilms, Little Salt Spring, Florida

    Science.gov (United States)

    Yang, E.; Schaperdoth, I.; Albrecht, H.; Freeman, K. H.; Macalady, J. L.

    2008-12-01

    filamentous cells with holdfasts are Epsilonproteobacteria. Additional FISH experiments will target the Betaproteobacterial and OP11/OD2 phylotypes retrieved by cloning. Based on HPLC-MS analyses, the biofilm contains at least 5 membrane hopanoid structures distinct from the suite of hopanoids present in sinking organic particles from the photic zone of the sinkhole. Future efforts will be aimed at linking hopanoid structures to specific sulfur-oxidizing populations and to geochemical parameters such as sulfide and oxygen concentrations. References Alvarez Zarikian,C. A., P. K. Swart, J. A. Gifford, P. L. Blackwelder, Palaeogeography, Palaeoclimatology, Palaeoecology 225, 134 (2005). Clausen, C. J., A. D. Cohen, C. Emiliani, J. A. Holman, J. J. Stipp, Science 203, 609 (1979).

  11. Coral cores collected in Dry Tortugas National Park, Florida, U.S.A.: Photographs and X-rays

    Science.gov (United States)

    Kuffner, Ilsa B.; Weinzierl, Michael S.; Reich, Christopher D.; Bartlett, Lucy A.; Flannery, Jennifer A.

    2016-01-01

    Cores from living coral colonies were collected from Dry Tortugas National Park, Florida, to obtain skeletal records of past coral growth and allow geochemical reconstruction of environmental variables during the corals’ centuries-long lifespans. The samples were collected as part of the U.S. Geological Survey (USGS) Coral Reef Ecosystems Studies project (http://coastal.er.usgs.gov/crest/) that provides science to assist resource managers tasked with the stewardship of coral reef resources. Three colonies each of the coral species Orbicella faveolata and Siderastrea siderea were collected in May 2012 as approved under National Park Service (NPS) scientific collecting permit number DRTO-2012-SCI-0001. These coral samples can be used to retroactively construct sea-surface temperature records by measuring the elemental ratio of strontium (Sr) to calcium (Ca), and are valuable for measuring additional paleoproxies as new methods are developed. Flannery et al. (In press) includes temperature reconstructions using samples from one of the six (coral CG2) collected in this study. The core slabs described here, as well as others (see http://olga.er.usgs.gov/coreviewer/), can be requested on loan for further scientific study. Here we provide photographic images for each core depicting 1) the coral in its ocean environment, 2) the core as curated and slabbed, and 3) the X-rays of the slabs. More information on coring methods can be found in the associated U.S. Geological Survey Open-File Report 2016-1182 (Weinzierl et al., 2016). These coral samples are presently on loan from the NPS, stored at the USGS St. Petersburg Coastal and Marine Science Center in St. Petersburg, Florida, and cataloged under accession number DRTO-353.Flannery, J. A., J. N. Richey, K. Thirumalai, R. Z. Poore, and K. L. DeLong, in press, Multi-species coral Sr/Ca based sea-surface temperature reconstruction using Orbicella faveolata and Siderastrea siderea from the Florida Straits: Palaeogeography

  12. Gratkorn - A new late Middle Miocene vertebrate fauna from Styria (Late Sarmatian, Austria)

    Science.gov (United States)

    Gross, M.; Böhme, M.; Prieto, J.

    2009-04-01

    Europe and will be confidentially one of the key faunas for a high-resolution continental biostratigraphy and the comprehension of the faunal succession and interchanges near the Middle/Late Miocene transition. Acknowledgements This is a preliminary overview of the Gratkorn vertebrate fauna. Several taxa are still under investigation. We are especially grateful to Gudrun Daxner-Höck, Ursula Göhlich (both Natural History Museum Vienna) and Getrud Rössner (University of Munich) for their comments to the rodents, ruminants, proboscidians and bird remains. References Böhme, M., Ilg, A., Winklhofer, M. 2008. Late Miocene "washhouse" climate in Europe.- Earth and Planetary Science Letters, 275: 393-401. Gross, M., 2008. A limnic ostracod fauna from the surroundings of the Central Paratethys (Late Middle Miocene/Early Late Miocene; Styrian Basin; Austria).- Palaeogeography, Palaeoclimatology, Palaeoecology, 264/3-4: 263-276. Harzhauser, M., Gross, M. & Binder, H., 2008. Biostratigraphy of Middle Miocene (Sarmatian) wetland systems in an Eastern Alpine intramontane basin (Gratkorn Basin, Austria): the terrestrial gastropod approach.- Geologica Carpathica, 59/1: 45-58.

  13. The potential of chemical fingerprinting of tephra for stratigraphic correlations in the fossil Lagerstätte of the Pisco Formation (Peru)

    Science.gov (United States)

    Bosio, Giulia; Gioncada, Anna; Malinverno, Elisa; Villa, Igor Maria; Di Celma, Claudio; Gariboldi, Karen; Urbina, Mario; Bianucci, Giovanni

    2017-04-01

    trace tephra layers from distant outcrop localities, allowing to refine the chronostratigraphy of the Pisco Formation in the western Ica River Valley. Bianucci G. et al (2016) Journal of Maps, 12: 1037-1046. Brand L.R. et al (2011) J. South Am. Earth Sci., 31: 414-425. Di Celma C. et al (2016) Journal of Maps, 12: 1020-1028. Esperante R. et al. (2015) Palaeogeography, Palaeoclimatology, Palaeoecology, 417: 337-370. Gariboldi K. et al (in press) Newsletters on Stratigraphy. Lowe D.J. (2011) Quaternary Geochronology, 6: 107-153.

  14. Holocene Millennial Time Scale Hydrological Changes In Central-east Africa

    Science.gov (United States)

    Jolly, D.; Bonnefille, R.; Beaufort, L.

    (Sirocko et al., 1996) and the Holocene. References Bond et al., Science,278, 1257 (1997) Bond et al., Science,294, 2130 (2001) Bonnefille &Umer, Palaeogeography, Palaeoclimatology, Palaeoecology, 109, 331 (1994) Gillespie et al., Nature, 306, 680 (1983) Schulz et al., Geophysical Research Letters, 26, 3385 (1999) Sirocko et al., Nature, 364, 322 (1993) Sirocko et al., Science, 272, 526 (1996) Wijmstra et al., Acta Botanica Neerlandica, 33, 547 (1984)

  15. A new age model for the Late Ordovician bentonites in Oslo, Norway

    Science.gov (United States)

    Gottschalk Ballo, Eirik; Eivind Augland, Lars; Hammer, Øyvind; Svensen, Henrik

    2017-04-01

    -bentonites) from the Oslo-Asker district". In: Norsk Geologisk Tidsskrift 35, pp. 29-52. Svensen, H. H., Hammer, Ø., and Corfu, F. (2015). "Astronomically forced cyclicity in the Upper Ordovician and U-Pb ages of interlayered tephra, Oslo Region, Norway". In: Palaeogeography, Palaeoclimatology, Palaeoecology 418, pp. 150-159.

  16. Variability in surface water properties of the southeastern South Atlantic Ocean related to the Miocene Cooling Events, evidence from calcareous dinoflagellate cysts.

    Science.gov (United States)

    Heinrich, S.; Zonneveld, K. A. F.; Willems, H.

    2009-04-01

    result of a northwards migration of the subantarctic front. References Miller, K.G., Wright, J.D., Fairbanks, R.G., 1991. Unlocking the Ice House: Oligocene-Miocene Oxygen Isotopes, Eustasy, and Margin Erosion. Journal of Geophysical Research, Vol. 96, No. B4: 6829-6848. Paulsen, H., Bickert, T., 2007. Benguela upwelling and global cooling in the middle to late Miocene - evidence from ODP Site 1085 planctonic foraminifer assemblages and isotopes. Palaeogeography, Palaeoclimatology, Palaeoecology, (subm.) Paulsen, H., Westerhold, T., Bickert, T., 2007. Middle to Late Miocene cooling history of the subantarctic Atlantic (ODP 1092). Geology, (subm.) St. John, K., 2008. Cenozoic ice-rafting history of the central Arctic Ocean: Terrigenous sands on the Lomonosov Ridge. Paleoceanography, Vol. 23, PA1S05.

  17. Sodium storage in deep paleoweathering profiles beneath the Paleozoic-Triassic unconformity

    Science.gov (United States)

    Thiry, M.; Parcerisa, D.; Ricordel-Prognon, C.; Schmitt, J.-M.

    2009-04-01

    in potassium. The Na+ enrichment is most likely linked with the peculiar geochemical setting of the Triassic environment where for instance halite moulds are very common in transgressive epicontinental deposits. The leaching of such salts, the role of salty marine aerosols, or a periodic/episodic contribution of seawater or evaporative solutions may be equally invoked. Mass balance Taking into account the surpergene origin of albitization and its widespread development on the Paleozoic basement rocks (from Morocco to Scandinavia) means that high amounts of Na+ have been stored in the deep paleoweathering profiles of the Triassic continents. This sodium storage in weathering profiles has to be taken in consideration in addition to the major sodium chloride accumulation in the basins during the Permo-Triassic times. Further investigations are needed to demonstrate the extent of these paleoweathering profiles and then to estimate the amount of this continental sodium storage. References Cathelineau M (1986) The hydrothermal alkali metasomatism effects on granitic rocks: Quartz dissolution and related sub-solidus changes. Jour. Petrol., 27: 945-965. Hay, W.W.; Migdisov, A.; Balukhovsky, A.N.; Wold, C.N.; Flogel, S., Soding, E. (2006) Evaporites and the salinity of the ocean during the Phanerozoic: Implications for climate, ocean circulation and life. Palaeogeography, Palaeoclimatology, Palaeoecology, 240/1-2: 3-46. Parcerisa D., Thiry M., Schmitt J.-M. (2009) Albitisation related to the Triassic unconformity in igneous rocks of the Morvan Massif (France), International Journal of Earth Sciences, DOI: 10.1007/s00531-008-0405-1. Petersson J, Eliasson T (1997) Mineral evolution and element mobility during episyenitization (dequartzification) and albitization in the postkinematic Bohus granite, southwest Sweden. Lithos, 42: 123-146. Ricordel C, Parcerisa D, Thiry M, Moreau M-G, Gómez-Gras D (2007) Triassic magnetic overprints related to albitization in granites from the

  18. The use of molecular chemistry (pyrolysis-GC/MS) in the environmental interpretation of peat

    NARCIS (Netherlands)

    Schellekens, J.

    2013-01-01

      The molecular composition of organic matter in peatlands reflects local conditions and stores information about botanical composition (plant source) as well as the degree of and conditions during decomposition. A reliable hydrological (and hence palaeoclimatological) interpretation of source

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

    Science.gov (United States)

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

    2016-04-01

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

  20. Record of palaeoenvironmental changes in the Mid-Polish Basin during the Valanginian Event

    Science.gov (United States)

    Morales, Chloé; Kujau, Ariane; Heimhofer, Ulrich; Mutterlose, Joerg; Spangenberg, Jorge; Adatte, Thierry; Ploch, Isabela; Föllmi, Karl B.

    2013-04-01

    closed to the early-late Valanginian boundary. This is associated to a decoupling of the δ13Ccarb and δ13Corg, which is interpreted as a change in atmospheric pCO2. References Erba, E., Bartolini, A. and Larson, L.R. (2004) Valanginian Weissert oceanic anoxic event. Geology, 32, 149-152. Föllmi, K.B., Bodin, S., Godet, A., Linder, P. and van de Schootbrugge, B. (2007) Unlocking paleo-environmental information from Early Cretaceous shelf sediments in the Helvetic Alps: stratigraphy is the key! Swiss journal of geosciences, 100, 349-369. Kujau, A., Heimhofer, U., Ostertag-Henning, C., Gréselle, B. and Mutterlose, J. (2012) No evidence for anoxia during the Valanginian carbon isotope event - an organic-geochemical study from the Vocontian Basin, SE France. Global and Planetary Change, doi: 10.1016/j.gloplacha.2012.04.007. Weissert, H., Lini, A., Föllmi, K.B. and Kuhn, O. (1998) Correlation of Early Cretaceous carbon isotope stratigraphy and platform drowning events: a possible link? Palaeogeography, Palaeoclimatology, Palaeoecology, 137, 189-203. Westermann, S., Caron, M., Fiet, N., Fleitmann, D., Matera, V., Adatte, T. and Föllmi, K.B. (2010) Evidence for oxic conditions during oceanic anoxic event 2 in the northern Tethyan pelagic realm. Cretaceous Research.

  1. Numerical analysis of palynological data from Neogene fluvial sediments as evidence for rainforest dynamics in western Amazonia

    Science.gov (United States)

    Salamanca, Sonia; van Manen, Milan; Hoorn, Carina

    2014-05-01

    associations, and b) estimate the palynological diversity along the sampled interval. Together these data suggest that the marine incursion altered the vegetation composition, but did not dramatically alter the diversity. After the marine incursion the vegetation returned to a modified version of the former floodplain forest. As yet no clear analogue has been found for this ancestral forest, but the palynological composition suggests a tropical rain forest to woody savanna. References Friendly, M., 2002. Correlograms: Exploratory Displays for Correlation Matrices. The American Statistician, 56, 316-324. Hoorn, 1994. Hoorn, C. (1994). Fluvial palaeoenvironments in the intracratonic Amazonas Basin (Early Miocene-early Middle Miocene, Colomnbian). Palaeogeography, Palaeoclimatology, Palaeoecology , vol 109, 1-54. Oksanen, J., Blanchet, F.G., Kindt, R., Legendre, P., Minchin, P.R., O'Hara, R. B., Simpson, G.L., Solymos, P., Henry, M. Stevensand, H., Wagner, H., 2013. Vegan: Community Ecology Package. R package version 2.0-8., J. 2012. R: A Language and Environment for Statistical Computing, R Foundation for Statistical Computing, 2013

  2. The Tendaguru formation of southeastern Tanzania, East Africa: An alternating Late Jurassic to Early Cretaceous palaeoenvironment of exceptional status

    Science.gov (United States)

    Sames, B.

    2009-04-01

    palaeoecological analysis of microfaunal and -floral assemblages confirms that the former subdivision of the Tendaguru formation into three non-marine intercalated with three marine layers should be recognised as generally only, because the formation is much more complex in detail. Application of calcareous microfossils has been demonstrated to make an important contribution to the interpretation of the Tendaguru formation's palaeoenvironment and is considered highly developable in the future. References: Aberhan, M., Bussert, R., Heinrich, W.-D., Schrank, E., Schultka, S., Sames, B., Kriwet, J. and Kapilima, S., 2002. Palaeoecology and depositional environments of the Tendaguru Beds (Late Jurassic to Early Cretaceous, Tanzania). Mitteilungen aus dem Museum für Naturkunde in Berlin, Geowissenschaftliche Reihe, 5: 19-44. Bussert, R. and Aberhan, M., 2004. Storms and tsunamis: evidence of event sedimentation in the Late Jurassic Tendaguru Beds of southeastern Tanzania. Journal of African Earth Sciences, 39: 549-555. Heinrich, W.-D., Bussert, R., Aberhan, M., Hampe, O., Kapilima, S., Schrank, E., Schultka, S., Maier, G., Msaky, E., Sames, B. and Chami, R., 2001. The German-Tanzanian Tendaguru Expedition 2000. Mitteilungen aus dem Museum für Naturkunde Berlin, Geowissenschaftliche Reihe, 20: 223-237. Sames, B., 2008. Application of Ostracoda and Charophyta from the Late Jurassic to Early Cretaceous Tendaguru formation at Tendaguru, Tanzania (East Africa) - Biostratigraphy, Palaeobiogeography and Palaeoecology. Palaeogeography, Palaeoclimatology, Palaeoecology, 264(3-4): 213-229.

  3. Reconstruction of the Palaeo-environment of the Alluvial Deposits in the Eastern Free State, South Africa

    Science.gov (United States)

    Evans, M. Y.

    2009-04-01

    section and 4,610 ±30 at the bottom section. References: Klein, R.G., Cruz-Uribe, K., Beaumont, P.B., 1991. Environmental, ecological, and paleoanthropological implications of the Late Pleistocene mammalian fauna from Equus Cave, northern Cape Province, South Africa. Quaternary Research. 36, 94 119. Lee-Thorp, J.A., Beaumont. PB., 1995. Vegetation and seasonality shift during the late Quaternary deduced from 13C/12C ratios of grazers at Equus Cave, South Africa. Quaternary Research. 43, 426 432. Partridge, T.C., Demenocal, P.B., Lorentz, S.A., Paiker, M.J., Vogel, J.C., 1997: Orbital forcing of climate over South Africa: A 200,000-year rainfall record from Pretoria Saltpan, Quaternary Science Reviews, 16, 1125-1133. Partridge, T.C., Kerr, S.J., Metcalfe, S.E., Scott, L., Vogel, J.C., 1993: The Pretoria Saltpan: A 200,000 year South African lacustrine sequence. Palaeogeography, Palaeoclimatology, Palaeoecology, 101, 317-337. Scott, L. and Thackeray, J.F., 1987: Multivariate analysis of late Pleistocene and Holocene pollen spectra from Wonderkrater, Transvaal, South Africa. South African Journal of Science, 83, 93- 98. Talma, A.S. and Vogel, J.C., 1992: Late Quaternary palaeotemperatures derived from a speleotherm from Cango Caves, Cape Province, South Africa, Quaternary Research, 37, 203-213. Vogel, J.C., 1983. Isotopic evidence for past climates and vegetation of southern Africa. Bothalia 14, 391-394.

  4. A Report of Guillain–Barré Syndrome With Myalgia and Mild Weakness

    OpenAIRE

    AMINZADEH, Vahid; Hassanzadeh Rad, Afagh

    2014-01-01

    How to Cite This Article: Aminzadeh V, Hassanzadeh Rad A. A Report of Guillain–Barré Syndrome With Myalgiaand Mild Weakness. Iran J Child Neurol. 2014 Spring; 8(2):70-72. We report a rare case that revealed severe myalgia as the chief complaint that is not mentioned in the list of frequent symptoms of Guillain Barré.Guillain-Barré syndrome (GBS) is an acute inflammatory demyelinating polyneuropathy (AIDP).Required features for diagnosis of GBS are progressive motor weakness of more than one l...

  5. Fellowship | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Rengaswamy Ph.D. (Gujarat), FNA, FNASc, FTWAS Council Service: 2016-. Date of birth: 2 June 1956. Specialization: Palaeoclimatology & Climate Modelling, Mass Spectrometry, and Oceanography Address: Senior Professor, Department of Earth & Planetary Sciences, National Institute of Science Education & Research, ...

  6. Sea-level changes vs. organic productivity as controls on Early and Middle Devonian bioevents: Facies- and gamma-ray based sequence-stratigraphic correlation of the Prague Basin, Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Bábek, O.; Faměra, M.; Šimíček, D.; Weinerová, H.; Hladil, Jindřich; Kalvoda, J.

    2018-01-01

    Roč. 160, January (2018), s. 75-95 ISSN 0921-8181 R&D Projects: GA ČR GA14-18183S Institutional support: RVO:67985831 Keywords : bioevents * carbonates * Devonian * eustatic cyclicity * palaeoclimatology * sequence stratigraphy Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.915, year: 2016

  7. Petrological, geochemical and isotopic characteristics of lignite and calcified lignite from mining area Pesje, Velenje Basin, Slovenia

    Science.gov (United States)

    Vrabec, Mirijam; Markič, Miloš; Vrabec, Marko; Jaćimović, Radojko; Kanduč, Tjaša

    2014-05-01

    energy dispersive X-ray spectroscopy at the Department of Ceramics at the Jožef Stefan Institute. Geochemical characteristics of major and trace elements indicate that the values of major and trace elements are comparable to world average coal (Zhang et al., 2004). Isotopic composition of carbon and isotopic composition of nitrogen of investigated samples indicate values from to -29.4o to -23.7o and 1.8o to 5.9o respectively. Lower value of isotopic composition of carbon indicates higher gelification (values up to -29.4) and higher value of isotopic composition of nitrogen (values up to 5.9) indicate higher mineralization. The results of SEM/EDXS microscopy revealed that in calcified lignite chemical composition of calcite prevails. Traces of diagenetic pyrite were also found, indicating localized anoxic conditions during sedimentation. Values of isotopic composition of CCaCO3 range from -2 to +13 and indicate temperature of precipitation from 17.3 to 35 deg C, which is similar to results obtained in previous studies (Kanduč et al., 2012). References Krantz, D.E., Williams, D.F., Jones, D.S., 1987: Ecological and paleoenvironmental information using stable isotope profiles from living and fossil mollusks. Palaeogeography, Palaeoclimatology, Palaeoecology 58, 249-266. Kanduč T., Markič M., Zavšek S., McIntosh J. 2012: carbon cycling in the Pliocene Velenje Coal Basin, Slovenia, inferred from stable carbon isotopes. International Journal of Coal Geology 89, 70-83. Jaćimović, R., Lazaru, A., Mihajlović, D., Ilić, R., Stafilov, T., 2002: Determination of major and trace elements in some minerals by k0-instrumental neutron activation analysis. Journal of Radioanalytical Nuclear Chemistry, 253, 427-434. McCrea, JM., 1950. On the isotopic chemistry of carbonates and a paleotemperature scale. Journal of Chemical Physics 18, 849. Ward C.R. (Ed.), 1984: Coal Geology and Coal Technology. Black-well, Oxford, 345 pp. Zhang J.Y., Zheng C.G., Ren D.Y., Chou C.L., Zheng R

  8. Post-fire changes in sediment transport connectivity from pedon to watershed scale. The Navalón wildfire in Eastern Spain

    Science.gov (United States)

    Cerdà, Artemi; Bodí, Merche B.; González, Óscar; Mataix Solera, Jorge; Doerr, Stefan Helmut

    2015-04-01

    ., Sheridan, G. J., Smith, H. G., Lane, P. N. J. (2012). Surface runoff and erosion after prescribed burning and the effect of different fire regimes in forests and shrublands: a review. International Journal of Wildland Fire, 21(7), 857-872. Cerdà, A., Lasanta, A. 2005. Long-term erosional responses after fire in the Central Spanish Pyrenees: 1. Water and sediment yield. Catena, 60, 59-80. Doerr, S., Cerdà, A. 2005. Fire effects on soil system functioning: new insights and future challenges International Journal of Wildland Fire Preface. International Journal of Wildland Fire 14(4) 339-342 Guénon, R., Vennetier, M., Dupuy, N., Roussos, S., Pailler, A., Gros, R. 2013. Trends in recovery of Mediterranean soil chemical properties and microbial activities after infrequent and frequent wildfires. Land Degradation & Development, 24: 115- 128. DOI 10.1002/ldr.1109 Kaiho, K., Yatsu, S., Oba, M., Gorjan, P., Casier, J. G., Ikeda, M. (2013). A forest fire and soil erosion event during the Late Devonian mass extinction. Palaeogeography, Palaeoclimatology, Palaeoecology, 392, 272-280. Lasanta, A., Cerdà, A. 2005. Long-term erosional responses after fire in the Central Spanish Pyrenees: 2. Solute release. Catena, 60, 80-101. Pérez-Cabello, F., Cerdà, A., de la Riva, J., Echeverría, M.T., García-Martín, A., Ibarra, P., Lasanta, T., Montorio, R., Palacios, V. 2012. Micro-scale post-fire surface cover changes monitored using high spatial resolution photography in a semiarid environment: A useful tool in the study of post-fire soil erosion processes, Journal of Arid Environments, 76: 88-96. 10.1016/j.jaridenv.2011.08.007 Prats, S.A., Malvar, M.C., Simões-Vieira, D.C., MacDonald, L., Keizer, J.J. 2015. Effectiveness of hydro- mulching to reduce runoff and erosion in a recently burnt pine plantation in central Portugal. Land Degradation & Development, DOI: 10.1002/ldr.2236.

  9. U-Pbdating on detrital zircon and Nd and Hf isotopes related to the provenance of siliciclastic rocks of the Amazon Basin: Implications for the origin of Proto-Amazonas River

    Science.gov (United States)

    Dantas, Elton Luiz; Silva Souza, Valmir; Nogueira, Afonso C. R.; Ventura Santos, Roberto; Poitrasson, Franck; Vieira Cruz, Lucieth; Mendes Conceição, Anderson

    2014-05-01

    provenance dominated by Mesoproterozoic sources (1.0, 1.2 Ga) and subordinate Neoproterozoic(550-800 Ma) and Archean derivation (2.67 Ga). On the other hand, detrital zircon and Hf and NdTDM model ages for the Cretaceous Alter do Chão Formation yielded a unique Paleoproterozoicages between 2.0 and 2.3 Ga that can be correlated to sources derived from Maroni-Itacaiúnas and Central Amazonian basement provinces. The contribution of Precambrian and Paleozoic rocks exposed during the installationof the Amazonas drainage were probably significant .Such a large contribution from Neoproterozoic and Mesoproterozoic sources are not common in the proximal Amazon Craton basement .This new proposal open new perspectives to understand better the initial history of Amazon River with indication of the probable source areas during Late Cenozoic. Campbell Jr.; Frailey,C.D.; Romero-Pittman, G. 2006. The Pan-Amazonian UcayliPeneplain, late Neogenesedimentacion in Amazonia, and the Birth on the Modern Amazon River system.Palaeogeography,Palaeoclimatology, Palaeoecology. 239 (2006) 166-219 Figueiredo, J.,Hoorn, C., Van der Vem, P., Soares, E. 2009. Late Miocene onset of the Amazon River and the Amazon deep-sea fan: Evidence from the Fozdo Amazonas Basin. Geology, 37(7):619-622. Hoorn,C.; Guerrero, J.; Sarmiento, G. 1995. Andean tectonics as a cause for changing drainage patterns in Miocene Northern South America. Geology, v.23, p-237-240. Nogueira, A.C.R.; Silveira, R.R.; Guimarães, J.T.F. 2013. Neogene-Quaternary sedimentary and paleovegetation history of the eastern Solimões Basin, central Amazon region.Journal of South American Earth Sciences , v. 46, p. 89-99, 2013. Potter, P.E. 1997. The Mesozoic and Cenozoic paleodrainage of South America: a natural history. Journal of South American Earth Science.v.10. p.331-344 Wesselingh, F. P., et al., 2002. Lake-Pebas: a palaeocological reconstruction of a Miocene long-lived lake comples in Western Amazônia. Cainozoic Research 1 (1-2), 35-81.

  10. Fish as a proxy for African paleogeography: results from both extant and fossil taxa and prospects to constrain faunal exchange pathway through time

    Science.gov (United States)

    Otero, Olga; Joordens, Josephine; Dettai, Agnès; Christ, Leemans; Pinton, Aurélie

    2016-04-01

    reveal ancient distributions. The further we are going back in time the more they will constitute most of or the whole relevant sample. Our results also suggest that information on the (paleo)ecology of the fish provides useful data notably to qualify the aquatic systems that have prevailed at the time of connection between basins. So, changes in basin geomorphology constrain fish evolution, and thus we are able to reconstruct and date these changes thanks to fish evolution studies. Since it is widely agreed that the identification of corridors and barriers is critical to understand faunal exchange, we are convinced that for each case study, we can identify the fish (either fossil or extant) that will provide a relevant "geomorphological model". To validate this approach, our current project aims to identify the exchange corridor that may have intermittently existed between the Chad and Turkana basins during the last 3 million years [6]. These corridors may have constituted possible pathways for interbasinal exchange of large mammals at a key time period of Australopithecine evolution. We will end our presentation with preliminary results concerning phylogeography of the extant catfish Synodontis schall, one of our three model species. [1] Pinton A., Otero O. in progress - How much do fish distribution depend on drainage system history? the case study of continental Africa. [2] Pinton A., Agnèse J.F., Paugy D., Otero O. 2013 - A large-scale phylogeny of Synodontis (Mochokidae, Siluriformes) reveals the influence of geological events on continental diversity during the Cenozoic. Molecular Phylogenetics and Evolution, 66 (2013): 1027-1040. [3] Otero O. 2011 - Current knowledge and new assumptions on the evolutionary history of the African lungfish, Protopterus, based on a review of its fossil record. Fish & Fisheries, 2011(12): 235-255. [4] Otero O., Pinton A., Mackaye H.T., Likius A., Vignaud P., Brunet M. 2009 - Fishes and palaeogeography of the African drainage basins

  11. Benthic faunal assemblages from the Holocene middle shelf of the South Evoikos Gulf, central Greece, and their palaeoenvironmental implications

    Science.gov (United States)

    Asimina Louvari, Markella; Tsourou, Theodora; Drinia, Hara; Anastasakis, George

    2013-04-01

    sedimentary history of the Bounty Trough, east of New Zealand. Palaeogeography, Palaeoclimatology, Palaeoecology, 211(1-2), 59-93, doi:10.1016/j.palaeo.2004.04.007 Sgarrella, F. & Moncharmon-Zei, M. 1993. Benthic foraminifera in the Gulf of Naples (Italy): systematic and autoecology, Boll. Soc. Palaeont. Ital. 32, 145-264. This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: THALIS -UOA-70/3/11669.

  12. Diplodon shells from Northwest Patagonia as continental proxy archives: Oxygen isotopic results and sclerochronological analyses

    Science.gov (United States)

    Soldati, A. L.; Beierlein, L.; Jacob, D. E.

    2009-04-01

    precipitation records in the region (from the NOAA database, station: airport of S.C. de Bariloche: 41°S-71°W). D. ch. patagonicus exhibit very well developed annual growth lines, which allow calibrating a precise temporal scale with calendar years in the shell (Soldati et al., 2008). Extremely wide increments (e.g. years 2000-2001 and 1978-1979), related to distinct periods (so-called benchmark increments) are present in all specimens and can be used to anchor the growth curves in order to create a master curve for the lake. ^18Oshell varies seasonally, presenting minima during the warm season (November/March) and maxima in the austral autumn/winter (April/October), reproducing the temperature fluctuations in the region. The resolution of the ^18Oshell measurement varies for each year: samples obtained from larger annual increments (>1 mm, generally mussels younger than 10 years old) allow a resolution of ca. 2 months (5-7 samples per year), and sometimes even give a 5 weeks resolution, while thinner annual increments (between 1 and 0.1 mm, generally older than 10 years) allow only a 4-6 month resolution (2-3 points per sampled year). Because of their long live span of ca. 100 years, Diplodon shells are useful to construct an accurate climatological archive for Patagonia with time windows of around a century, resolving the environmental signal annually and even seasonally. References: CASTELLANOS Z.A. (1960). Almejas nacaríferas de la República Argentina. Género Diplodon. Secretaría de Agricultura, Publicación Miscelánea, 421: 1-40. KAANDORP R.J.G., VONHOF H.B., WESSELINGH F.P., PITTMAN L.R., KROON D. & HINTE J.E.V. (2005). Seasonal Amazonian rainfall variation in the Miocene Climate Optimum. Palaeogeography, Palaeoclimatology, Palaeoecology, 221: 1-6. SOLDATI A.L., JACOB D.E., SCHÖNE B.R., BIANCHI M.M., HAJDUK A. (2008). Seasonal periodicity of growth and composition in valves of Diplodon chilensis patagonicus (D'Orbigny, 1835). Journal of Molluscan Studies, doi:10

  13. Permian fauna of the Krkonoše Piedmont Basin (Bohemian Massif, Central Europe)

    Czech Academy of Sciences Publication Activity Database

    Zajíc, Jaroslav

    2014-01-01

    Roč. 70, 3/4 (2014), s. 131-142 ISSN 0036-5343 Institutional support: RVO:67985831 Keywords : faunal lists * palaeogeography * palaeoenvironment * stratigraphy * Early Permian * Krkonoše Piedmont Basin * Bohemian Massif Subject RIV: DB - Geology ; Mineralogy

  14. Timing, cause and impact of the late Eocene stepwise sea retreat from the Tarim Basin (west China)

    NARCIS (Netherlands)

    Bosboom, R.|info:eu-repo/dai/nl/322947359; Dupont-Nivet, G.|info:eu-repo/dai/nl/313092559; Grothe, A.|info:eu-repo/dai/nl/338017712; Brinkhuis, H.|info:eu-repo/dai/nl/095046097; Villa, G.; Mandic, O.; Stoica, M.; Kouwenhoven, T.J.|info:eu-repo/dai/nl/191377406; Huang, W.; Yang, W.; Guo, Z.

    2014-01-01

    A vast shallow epicontinental sea extended across Eurasia and was well-connected to the Western Tethys before it retreated westward and became isolated as the Paratethys Sea. However, the palaeogeography and the timing of this westward retreat are too poorly constrained to determine potential wider

  15. The use of molecular chemistry (pyrolysis-GC/MS) in the environmental interpretation of peat

    OpenAIRE

    J. Schellekens

    2013-01-01

      The molecular composition of organic matter in peatlands reflects local conditions and stores information about botanical composition (plant source) as well as the degree of and conditions during decomposition. A reliable hydrological (and hence palaeoclimatological) interpretation of source and decomposition proxies in peatlands requires the understanding of the interactions between decomposition and botanical composition and the reaction of both to changes in the water table. Only fe...

  16. Disappearance of the last lions and hyenas of Europe in the Late Quaternary - a chain reaction of large mammal prey migration, extinction and human antagonism

    Science.gov (United States)

    Diedrich, Cajus G.

    2010-05-01

    . in prep. Coelodonta antiquitatis (Blumenbach 1799) hunters and scavengers - the Late Pleistocene spotted hyena Crocuta crocuta spelaea (Goldfuss 1823) and its feeding strategy on its most important prey in Europe. Diedrich, C. in review a. A diseased Panthera leo spelaea (Goldfuss, 1810) lioness from a forest elephant graveyard in the Late Pleistocene (Eemian) interglacial lake at Neumark-Nord, Central Germany. Quaternary International. Diedrich, C. in review b. Late Pleistocene steppe lion Panthera leo spelaea (Goldfuss, 1810) remains from the open air hyena den Emscher River terrace site Bottrop and other sites of northern Germany - new proves for hyena-lion antagonism. Palaeogeography, Palaeoclimatology, Palaeoecology. DIEDRICH, C. in review c. The Crocuta crocuta spelaea (GOLDFUSS 1823) population and its prey from the Upper Pleistocene Teufelskammer Cave hyena den site in the Neandertal (NRW, NW Germany). Annales de Paléontologie. Diedrich, C. in review d. The Late Pleistocene Crocuta crocuta spelaea (Goldfuss, 1823) population from the Late Pleistocene hyena open air Emscher River terrace den near Bottrop (NWGermany) and other sites in the Westphalian Bay and its mammoth and woolly rhinoceros prey. Quaternary International. Diedrich, C. and Rathgeber, T. in review. Late Pleistocene steppe lion Panthera leo spelaea (Goldfuss, 1810) skeleton remains of the Upper Rhine valley (SW Germany) and contribution to their palaeobiogeography, sexual dimorphism and palaeoecology. Palaeogeography Palaeoclimatology Palaeoecology. Diedrich, C. AND Žák, K. 2006. Prey deposits and den sites of the Upper Pleistocene hyena Crocuta crocuta spelaea (Goldfuss, 1823) in horizontal and vertical caves of the Bohemian Karst (Czech Republic). Bulletin of Geosciences, 81 (4), 237-276. Günther, K. 1964. Die altsteinzeitlichen Funde der Balve Höhle. Bodenaltertümer Westfalens, 8, 1-165. Günther, K. 1988. Alt- und Mittelsteinzeitliche Fundplätze in Westfalen. Teil 2. Einführung in

  17. Spotted hyena and steppe lion predation behaviours on cave bears of Europe - ?Late Quaternary cave bear extinction as result of predator stress

    Science.gov (United States)

    Diedrich, Cajus G.

    2010-05-01

    . (in review). Cave bear killers and scavengers from the last European Ice Age. Palaeogeography Palaeoclimatology Palaeoecology. Diedrich, C., Žák, K. 2006. Prey deposits and den sites of the Upper Pleistocene hyena Crocuta crocuta spelaea (Goldfuss, 1823) in horizontal and vertical caves of the Bohemian Karst (Czech Republic). Bulletin of Geosciences, 81 (4), 237-276. Diedrich, C., Robu, M., Dragusin, V., Constantin, S., Moldovan, O., 2009. New Upper Pleistocene steppe lion skeleton finds between the cave bear hibernation plateaus of the Ursilor Cave bear den, Romania. Abstractc 15th International Cave Bear Symposium, Spisska Nova Ves Slovakia, 10. Diedrich, C., Moldovan, O., Constantin, S. 2009. Cave bear tracks, scratch marks, hair traces and hibernation nests in the Ursilor Cave (Transylvania, Romania) - preliminary report from a famous European cave bear den. - Stalactite, 58 (2): 48-52. Diedrich, C., Moldovan, O. 2010. Ichnological and ethological studies in one of Europe's famous bear den in the Ursilor Cave (Carpathians, Romania). - Quarternary International (accepted). Rabeder, G., Nagel, D., Pacher, M., 2000. Der Höhlenbär. Stuttgart: Thorbecke.

  18. Glacial recession in the Tropical Andes from the Little Ice Age: the case of Ampato Volcanic Complex (Southern Peru

    Science.gov (United States)

    Alcalá, J.; Palacios, D.; Zamorano, J. J.

    2010-03-01

    Europa (Cordillera Cantábrica, NO de España). Análisis morfológico y reconstrucción del avance glaciar histórico. Rev. C & G., 19 (3-4), 79-94. Hastenrath, S. L. (2009): Past glaciation in the tropics. Quaternary Science Reviews, 28: 790-798. Jomelli, V.; Favier, V.; Rabatel, A.; Brunstein, D.; Hoffmann, G.; and Francou, B. (2009): Fluctuations of glaciers in the tropical Andes over the last millennium and palaeoclimatic implications: A review. Palaeogeography, Palaeoclimatology, Palaeoecology, doi: 10.1016/j.palaeo.2008.10.033. Kaser, G., Osmaston, H.A., 2002. Tropical glaciers. Cambridge University Press, Cambridge. Mark, B. (2008): Tracing tropical Andean glaciers over space and time: Some lessons and transdisciplinary implications. Global and Planetary Change, 60: 101-114. Osmaston, H. (2005): Estimates of glacier equilibrium line altitudes by the Area _ Altitude, the Area _ Altitude Balance Ratio and the Area _ Altitude Balance Index Methods and their validation. Quaternary International, 138-139: 22-31. Rabatel, A., Jomelli, V., Naveau, P., Francou, B., Grancher, D. (2005). Dating of Little Ice Age glacier fluctuations in the tropical Andes: Charquini glaciers, Bolivia, 16ºS. C. R. Geoscience, 337: 1311-1322. Rabatel, A., Francou, B., Jomelli, V., Naveau, P., Grancher, D. (2008). A chronology of the Little Ice Age in the tropical Andes of Bolivia (16º S) and its implications for climate reconstruction. Quaternary Research, 70: 198-212. Ramirez, E., Francou, B., Ribstein, P., Descloitres, M., Guerin, R., Mendoza, J., Gallaire, R., Pouyaud, B., Jordan, E., 2001. Small glaciers disappearing in the tropical Andes: a case study in Bolivia: Glaciar Chacaltaya (16°S). Journal of Glaciology 47 (157), 187-194. Soruco, A.; Vincent, C.; Francou, B.; Ribstein, P.; Berger, T.; Sicart, J. E.; Wagnon, P.; Arnaud, Y.; Favier, V.; and Lejeune, Y. (2009): Mass balance of Glacier Zongo, Bolivia, between 1956 and 2006, using glaciological, hydrological and geodetic methods

  19. Mesozoic basins and associated palaeogeographic evolution in North China

    OpenAIRE

    Liu, Yong-Qing; Kuang, Hong-Wei; Peng, Nan; Xu, Huan; Zhang, Peng; Wang, Neng-Sheng; An, Wei; Wang, Yuan; Liu, Min; Hu, Xiu-Fang

    2015-01-01

    In North China, the Mesozoic terrestrial basins, sedimentary palaeogeography and tectonic settings involved five evolutionary stages: (1) the Early‒Middle Triassic, (2) the Late Triassic to Early‒Middle Jurassic, (3) the Late Jurassic to early Early Cretaceous, (4) the middle‒late Early Cretaceous and (5) the Late Cretaceous. The regional punctuated tectonic events occurred during these evolutionary stages. During the Early‒Middle Triassic (stage 1), the Xingmeng Orogenic Belt (XMOB, i.e.,...

  20. Evolution of the Asian monsoon from the Cretaceous to the modern - a modelling study.

    Science.gov (United States)

    Lunt, Dan; Farnsworth, Alex; Loptson, Claire; Markwick, Paul

    2014-05-01

    It has long been suggested that palaeogeography could have an important role in the modulation of the Asian monsoon. In particular, orogenesis associated with the Himalayas and Tibetan Plateau has been associated with the intensification of the Asian monsoon through the Neogene, a paradigm which has some support from both data and modelling studies. Here we go further by considering the evolution of the Asian monsoon over a much longer time period than ususally considered, namely, the early Cretaceous right through to the modern day. Through a series of more than 30 climate model simulations spanning 150 million years, we investigate how changing palaeogeography (continental distribution, mountain height, and bathymetry) has affected monsoon evolution. The palaeogeographies are provided by Getech Plc, and we use the HadCM3L climate model, developed by the UK Met Office. All simulations are run for more than 500 years from an identical initial state. We show that a monsoon system has existed in the western Pacific and Indian Ocean since the early Cretaceous, but that intense precipitation only began to penetrate onto the east Asian continent in the late Paleogene and early Eocene. As well as focussing on the Asian (or proto-Asian for the earliest Cretaceous) monsoon, we present the results in a global context.

  1. Thermoluminescence dating of sand dunes in Rajasthan, India

    Science.gov (United States)

    Singhvi, A. K.; Sharma, Y. P.; Agrawal, D. P.

    1982-01-01

    We report here a new application of thermoluminescence (TL) for dating sand dunes. This application assumes that exposure to sunlight causes bleaching of the geological TL of a sediment to a residual value and that TL accumulation starts again when the sediment is buried under fresh deposit and is thus shielded from the Sun. Although the TL method has been applied to loess1,2 and ocean sediments3,4, the application of this technique to sand dunes provides the first reliable dating control for dune dynamics, palaeoclimatology and spread of deserts.

  2. Climate sensitivity of Mediterranean pine growth reveals distinct east-west dipole

    Czech Academy of Sciences Publication Activity Database

    Seim, A.; Treydte, K.; Trouet, V.; Frank, D.; Fonti, P.; Tegel, W.; Panayotov, M.; Fernandez-Donado, L.; Krusic, P.; Büntgen, Ulf

    2015-01-01

    Roč. 35, č. 9 (2015), s. 2503-2513 ISSN 0899-8418 R&D Projects: GA MŠk(CZ) EE2.3.20.0248 Institutional support: RVO:67179843 Keywords : tree-ring width * scots pine * wood formation * ice core * variability * drought * precipitation * reconstructions * circulation * dynamics * climate dynamics * dendroclimatology * drought response * Mediterranean east-west dipole * palaeoclimatology * Pinus spp * principal component analysis * tree-ring width Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.609, year: 2015

  3. Spotlight on multiparametric magnetic resonance imaging in prostate cancer management: current perspectives

    Directory of Open Access Journals (Sweden)

    Hassanzadeh E

    2016-11-01

    Full Text Available Elmira Hassanzadeh, Clare M Tempany Division of Abdominal Imaging and Intervention, Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA Abstract: Clinical behavior of prostate cancer, the most common noncutaneous cancer in men, ranges from a nonsignificant indolent tumor to an aggressive cancer. Prostate cancer is subject to overdiagnosis and overtreatment, making screening, diagnosis, and treatment planning a controversial issue. Recently, even noninvasive simple screening methods such as prostate-specific antigen level and digital rectal examination are no longer recommended for screening as it has resulted in no reduction in mortality. Diagnosis and further treatment planning, however, are still based on a random transrectal ultrasound-guided biopsy, an invasive method with controversial efficacy that has been deemed as unnecessarily revealing nonsignificant tumors. Magnetic resonance (MR-based techniques are emerging that provide noninvasive tools that are promising in the detection of clinically significant lesions and accurate staging. Moreover, MR imaging improves the performance of image-guided procedures, both in diagnosis and therapy. We focus here on recent advances in multiparametric MR imaging in prostate cancer diagnosis and provide a brief overview of other emerging techniques. Keywords: multiparametric MRI, prostate cancer, image-guided intervention, PIRADS

  4. Reconciling late Quaternary transgressions in the Bohai Sea, China to the global sea level changes, and new linkage of sedimentary records to three astronomical rhythms

    Science.gov (United States)

    Yi, Liang

    2013-04-01

    Terminations. Science 326, 248-252. Ding, Z.L., Yu, Z.W., Rutter, N.W., Liu, T.S., 1994. Towards an orbital time scale for chinese loess deposits. Quaternary Science Reviews 13, 39-70. IOCAS (Institute of Oceanology, Chinese Academy of Sciences), 1985. Bohai Sea Geology. Science Press, Beijing, China. Liu, T., 2009. Loess and Arid Environment. Anhui Science & Techonology Press, Hefei, China. Wang, Y., Cheng, H., Edwards, R.L., An, Z., Wu, J., Chen, C.-C., Dorale, J.A., 2001. A High-Resolution Absolute-Dated Late Pleistocene Monsoon Record from Hulu Cave, China. Science 294, 2345-2348. Wang, Y., Cheng, H., Edwards, R.L., Kong, X., Shao, X., Chen, S., Wu, J., Jiang, X., Wang, X., An, Z., 2008. Millennial- and orbital-scale changes in the East Asian monsoon over the past 224,000 years. Nature 451, 1090-1093. Yi, L., Yu, H., Ortiz, J.D., Xu, X., Chen, S., Ge, J., Hao, Q., Yao, J., Shi, X., Peng, S., 2012a. Late Quaternary linkage of sedimentary records to three astronomical rhythms and the Asian monsoon, inferred from a coastal borehole in the south Bohai Sea, China. Palaeogeography, Palaeoclimatology, Palaeoecology 329-310, 101-117. Yi, L., Lai, Z.P., Yu, H.J., Xu, X.Y., Su, Q., Yao, J., Wang, X.L., Shi, X., 2012b. Chronologies of sedimentary changes in the south Bohai Sea, China: Constraints from luminescence and radiocarbon dating. Boreas, doi: 10.1111/j.1502-3885.2012.00271.x. Yi, L., Yu, H.J., Ortiz, J.D., Xu, X.Y., Qiang, X.K., Huang, H.J., Shi, X., Deng, C.L., 2012c. A reconstruction of late Pleistocene relative sea level in the south Bohai Sea, China, based on sediment grain-size analysis. Sedimentary Geology 281, 88-100. Zhao, S., Yang, G., Cang, S., Zhang, H., Huang, Q., Xia, D., Wang, Y., Liu, F., Liu, C., 1978. Transgression's stratas and shoreline changes in the south coast of Bohai Bay, China. Oceanologia et Limnologia Sinica 9, 15-25.

  5. Polar ice sheets during the Cretaceous? Insights from coupled numerical modelling.

    Science.gov (United States)

    Ladant, Jean-Baptiste; Donnadieu, Yannick

    2017-04-01

    Most proxy estimates of Cretaceous climates reveal oceanic and terrestrial temperatures substantially warmer than modern's. Fossils of crocodilian species and remains of what is now low-latitude flora have been unearthed in polar locations. On top of that, direct evidence of polar ice sheets have yet to be found. The Cretaceous has thus historically been considered as a long and stable period of supergreenhouse with elevated CO2 levels. Since a couple of decades however, studies have suggested that dynamical climatic variations affect the Cretaceous greenhouse, in particular with the episodic growth of ephemeral polar ice sheets, for which indirect evidence have been argued for. In addition, new estimates of CO2 levels suggest more modest values (400 - 1500 ppm), potentially in the range of those in place during Cenozoic glaciations. Here, we use a suite of models of climate and ice sheets to investigate the impact of the changing palaeogeography during the Middle-Late Cretaceous (120 - 70 Ma) on the development of ice sheets on polar latitudes. We show that palaeogeography alone, through a series of complex feedbacks, has the potential to significantly alter the CO2 threshold for the onset of ice sheets, nucleating in particular at higher CO2 concentrations in the Aptian ( 800 ppm) and the Maastrichtian ( 700 ppm) than in the Cenomanian-Turonian ( 400 ppm). Our simulations demonstrate notably that part of the Cenomanian-Turonian climatic optimum can be explained by its specific palaeogeography and support the vision of an ice-free Earth during this stage. In addition, our numerical work derives Aptian and Maastrichtian glacial CO2 threshold that are in the range of latest data compilations, thus adding to the growing body of evidence suggesting that ice sheets were once present during these stages.

  6. Advancing Precambrian palaeomagnetism with the PALEOMAGIA and PINT(QPI) databases

    Science.gov (United States)

    Veikkolainen, Toni H.; Biggin, Andrew J.; Pesonen, Lauri J.; Evans, David A.; Jarboe, Nicholas A.

    2017-05-01

    State-of-the-art measurements of the direction and intensity of Earth's ancient magnetic field have made important contributions to our understanding of the geology and palaeogeography of Precambrian Earth. The PALEOMAGIA and PINT(QPI) databases provide thorough public collections of important palaeomagnetic data of this kind. They comprise more than 4,100 observations in total and have been essential in supporting our international collaborative efforts to understand Earth's magnetic history on a timescale far longer than that of the present Phanerozoic Eon. Here, we provide an overview of the technical structure and applications of both databases, paying particular attention to recent improvements and discoveries.

  7. Were sauropod dinosaurs responsible for the warm Mesozoic climate?

    Directory of Open Access Journals (Sweden)

    A.J. (Tom van Loon

    2012-10-01

    Full Text Available It was recently postulated that methane production by the giant Mesozoic sauropod dinosaurs was larger than the present-day release of this greenhouse gas by nature and man-induced activities jointly, thus contributing to the warm Mesozoic climate. This conclusion was reached by correct calculations, but these calculations were based on unrealistic assumptions: the researchers who postulated this dinosaur-induced warm climate did take into account neither the biomass production required for the sauropods' food, nor the constraints for the habitats in which the dinosaurs lived, thus neglecting the palaeogeographic conditions. This underlines the importance of palaeogeography for a good understanding of the Earth's geological history.

  8. Integrating multiple lines of evidence into historical biogeography hypothesis testing: a Bison bison case study.

    Science.gov (United States)

    Metcalf, Jessica L; Prost, Stefan; Nogués-Bravo, David; DeChaine, Eric G; Anderson, Christian; Batra, Persaram; Araújo, Miguel B; Cooper, Alan; Guralnick, Robert P

    2014-02-22

    One of the grand goals of historical biogeography is to understand how and why species' population sizes and distributions change over time. Multiple types of data drawn from disparate fields, combined into a single modelling framework, are necessary to document changes in a species's demography and distribution, and to determine the drivers responsible for change. Yet truly integrated approaches are challenging and rarely performed. Here, we discuss a modelling framework that integrates spatio-temporal fossil data, ancient DNA, palaeoclimatological reconstructions, bioclimatic envelope modelling and coalescence models in order to statistically test alternative hypotheses of demographic and potential distributional changes for the iconic American bison (Bison bison). Using different assumptions about the evolution of the bioclimatic niche, we generate hypothetical distributional and demographic histories of the species. We then test these demographic models by comparing the genetic signature predicted by serial coalescence against sequence data derived from subfossils and modern populations. Our results supported demographic models that include both climate and human-associated drivers of population declines. This synthetic approach, integrating palaeoclimatology, bioclimatic envelopes, serial coalescence, spatio-temporal fossil data and heterochronous DNA sequences, improves understanding of species' historical biogeography by allowing consideration of both abiotic and biotic interactions at the population level.

  9. On palaeogeographic map

    Directory of Open Access Journals (Sweden)

    Zeng-Zhao Feng

    2016-01-01

    Full Text Available The palaeogeographic map is a graphic representation of physical geographical characteristics in geological history periods and human history periods. It is the most important result of palaeogeographic study. The author, as the Editor-in-Chief of Journal of Palaeogeography, Chinese Edition and English Edition, aimed at the problems of the articles submitted to and published in the Journal of Palaeogeography in recent years and the relevant papers and books of others, and integrated with his practice of palaeogeographic study and mapping, wrote this paper. The content mainly includes the data of palaeogeographic mapping, the problems of palaeogeographic mapping method, the “Single factor analysis and multifactor comprehensive mapping method —— Methodology of quantitative lithofacies palaeogeography”, i.e., the “4 steps mapping method”, the nomenclature of each palaeogeographic unit in palaeogeographic map, the explanation of each palaeogeographic unit in palaeogeographic map, the explanation of significance of palaeogeographic map and palaeogeographic article, the evaluative standards of palaeogeographic map and palaeogeographic article, and the self-evaluation. Criticisms and corrections are welcome.

  10. Toward the laboratory identification of the not-so-simple NS2 neutral and anion isomers

    Science.gov (United States)

    Fortenberry, Ryan C.; Thackston, Russell; Francisco, Joseph S.; Lee, Timothy J.

    2017-08-01

    The NS2 radical is a simple arrangement of atoms with a complex electronic structure. This molecule was first reported by Hassanzadeh and Andrew's group [J. Am. Chem. Soc. 114, 83 (1992)] through Ar matrix isolation experiments. In the quarter century since this seminal work was published, almost nothing has been reported about nitrogen disulfide even though NS2 is isovalent with the common NO2. The present study aims to shed new insight into possible challenges with the characterization of this radical. No less than three potential energy surfaces all intersect in the C2v region of the SNS radical isomer. A type-C Renner-Teller molecule is present for the linear 2Πu state where the potential energy surface is fully contained within the 2.05 kcal/mol lower energy X ˜ 2A1 state. A C2v, 1 2B1 state is present in this same region, but a double excitation is required to access this state from the X ˜ 2A1 state of SNS. Additionally, a 1 2A' NSS isomer is also present but with notable differences in the geometry from the global minimum. Consequently, the rovibronic spectrum of these NS2 isomers is quite complicated. While the present theory and previous Ar matrix experiments agree well on isotopic shifts, they differ notably for the absolute fundamental vibrational frequency transitions. These differences are likely a combination of matrix shifts and issues associated with the neglect of non-adiabatic coupling in the computations. In either case, it is clear that high-resolution gas phase experimental observations will be complicated to sort. The present computations should aid in their analysis.

  11. Characterization of Poliovirus Neutralization Escape Mutants of Single-Domain Antibody Fragments (VHHs)

    Science.gov (United States)

    Schotte, Lise; Thys, Bert; Strauss, Mike; Filman, David J.; Rombaut, Bart

    2015-01-01

    To complete the eradication of poliovirus and to protect unvaccinated people subsequently, the development of one or more antiviral drugs will be necessary. A set of five single-domain antibody fragments (variable parts of the heavy chain of a heavy-chain antibody [VHHs]) with an in vitro neutralizing activity against poliovirus type 1 was developed previously (B. Thys, L. Schotte, S. Muyldermans, U. Wernery, G. Hassanzadeh-Ghassabeh, and B. Rombaut, Antiviral Res 87:257–264, 2010, http://dx.doi.org/10.1016/j.antiviral.2010.05.012), and their mechanisms of action have been studied (L. Schotte, M. Strauss, B. Thys, H. Halewyck, D. J. Filman, M. Bostina, J. M. Hogle, and B. Rombaut, J Virol 88:4403–4413, 2014, http://dx.doi.org/10.1128/JVI.03402-13). In this study, neutralization escape mutants were selected for each VHH. Sequencing of the P1 region of the genome showed that amino acid substitutions are found in the four viral proteins of the capsid and that they are located both in proximity to the binding sites of the VHHs and in regions further away from the canyon and hidden beneath the surface. Characterization of the mutants demonstrated that they have single-cycle replication kinetics that are similar to those of their parental strain and that they are all drug (VHH) independent. Their resistant phenotypes are stable, as they do not regain full susceptibility to the VHH after passage over HeLa cells in the absence of VHH. They are all at least as stable as the parental strain against heat inactivation at 44°C, and three of them are even significantly (P < 0.05) more resistant to heat inactivation. The resistant variants all still can be neutralized by at least two other VHHs and retain full susceptibility to pirodavir and 35-1F4. PMID:26014941

  12. A regime shift in the Sun-Climate connection with the end of the Medieval Climate Anomaly.

    Science.gov (United States)

    Smirnov, D A; Breitenbach, S F M; Feulner, G; Lechleitner, F A; Prufer, K M; Baldini, J U L; Marwan, N; Kurths, J

    2017-09-11

    Understanding the influence of changes in solar activity on Earth's climate and distinguishing it from other forcings, such as volcanic activity, remains a major challenge for palaeoclimatology. This problem is best approached by investigating how these variables influenced past climate conditions as recorded in high precision paleoclimate archives. In particular, determining if the climate system response to these forcings changes through time is critical. Here we use the Wiener-Granger causality approach along with well-established cross-correlation analysis to investigate the causal relationship between solar activity, volcanic forcing, and climate as reflected in well-established Intertropical Convergence Zone (ITCZ) rainfall proxy records from Yok Balum Cave, southern Belize. Our analysis reveals a consistent influence of volcanic activity on regional Central American climate over the last two millennia. However, the coupling between solar variability and local climate varied with time, with a regime shift around 1000-1300 CE after which the solar-climate coupling weakened considerably.

  13. Procedures for extraction and purification of leaf wax biomarkers from peats

    Directory of Open Access Journals (Sweden)

    J.E. Nichols

    2011-12-01

    Full Text Available Palaeoecological and palaeoclimate reconstruction, using leaf wax biomarkers, is a relatively new sub-discipline of peatland science. The ability to process large numbers of samples rapidly for biomarkers makes this type of analysis particularly appealing. This review is a guide to the preparation of leaf waxes for analysis by gas chromatography. The main phases of preparation are extraction of soluble organic compounds from sediment, separation of the total extract into fractions of differing polarity, and the derivatisation of polar functional groups. The procedures described here are not meant be exhaustive of all organic geochemical possibilities in peatlands, but a distillation of methods for the preparation of leaf waxes that are commonly and increasingly being used in palaeoecological and palaeoclimatological studies.

  14. Using data assimilation to study extratropical Northern Hemisphere climate over the last millennium

    Directory of Open Access Journals (Sweden)

    M. Widmann

    2010-09-01

    Full Text Available Climate proxy data provide noisy, and spatially incomplete information on some aspects of past climate states, whereas palaeosimulations with climate models provide global, multi-variable states, which may however differ from the true states due to unpredictable internal variability not related to climate forcings, as well as due to model deficiencies. Using data assimilation for combining the empirical information from proxy data with the physical understanding of the climate system represented by the equations in a climate model is in principle a promising way to obtain better estimates for the climate of the past.

    Data assimilation has been used for a long time in weather forecasting and atmospheric analyses to control the states in atmospheric General Circulation Models such that they are in agreement with observation from surface, upper air, and satellite measurements. Here we discuss the similarities and the differences between the data assimilation problem in palaeoclimatology and in weather forecasting, and present and conceptually compare three data assimilation methods that have been developed in recent years for applications in palaeoclimatology. All three methods (selection of ensemble members, Forcing Singular Vectors, and Pattern Nudging are illustrated by examples that are related to climate variability over the extratropical Northern Hemisphere during the last millennium. In particular it is shown that all three methods suggest that the cold period over Scandinavia during 1790–1820 is linked to anomalous northerly or easterly atmospheric flow, which in turn is related to a pressure anomaly that resembles a negative state of the Northern Annular Mode.

  15. The response of stromatolites to seismic shocks: Tomboliths from the Palaeoproterozoic Chaibasa Formation, E India: Discussion and liquefaction basics

    Directory of Open Access Journals (Sweden)

    G. Shanmugam

    2017-07-01

    Full Text Available This discussion of a paper by Van Loon et al. (2016, published in the Journal of Palaeogeography (2016, 5(4, 381–390, is aimed at illustrating that there are fundamental deficiencies, which include (1 incomplete etymological reasoning for proposing a new genetic term “tomboliths” for stromatolitic bioclasts in the Palaeoproterozoic Chaibasa Formation, eastern India, (2 omission of empirical data in documenting depositional facies using sedimentological logs, (3 misapplication of the stratigraphic concept of “angular unconformity”, (4 failure to consider the multifarious origins of earthquakes, and (5 a dated view on the basic tenets of process sedimentology and triggering mechanisms of liquefaction that are the basis for forming soft-sediment deformation structures (SSDS. As a consequence, their conclusions are unconvincing.

  16. The Possible Role of Climatic Changes In Later Pleistocene Human Evolution and Extinctions

    Science.gov (United States)

    Stringer, C.

    Problems of chronological resolution greatly restrict our ability to match the Pleis- tocene fossil human succession to detailed palaeoclimatic records. This talk will ad- dress two relevant research areas. The first concerns the ancient human occupation of Britain, now the focus of a specific project (AHOB). Human occupation of Britain was influenced by two main factors, palaeogeography (particularly in relation to the periodic absence of a land bridge, largely controlled by climate) and palaeoclimate (particularly influenced by conditions in the North Atlantic). The second area con- cerns the European extinction of the Neanderthals and their replacement by modern humans. Particularly in the latter case, if we can move beyond reliance on uncalibrated radiocarbon chronologies, we may eventually be able to correlate human demographic changes, including Neanderthal extinction, with rapid climatic fluctuations.

  17. The Neoproterozoic Drift History of Laurentia: a Critical Evaluation and new Palaeomagnetic Data from Northern and Eastern Greenland

    DEFF Research Database (Denmark)

    Christiansen, Jørgen Løye

    tillite yield a stable magnetization that passes fold and reversal tests and places this margin of Laurentia at a high palaeolatitude (~70°) during deposition &150; this result is being confirmed by analysis of a second suite of samples collected in 2007. Interestingly, this would suggest that late...... margin at a latitude of ~17° at this time. Collectively these data agree with models that have Laurentia moving into high latitudes in the latest Neoproterozoic. The required plate velocities, although high, are in the range for Phanerozoic continents. --------------------------------------------------------------------------------...... of glaciation. Most models agree that Laurentia straddled the equator at about 750Ma, during the early stages of Rodinia breakup, and was again in an equatorial position by the early Cambrian. Its palaeogeography between these times, however, has proven to be contentious with essentially two schools of thought...

  18. Facies-succession and architecture of the third-order sequences and their stratigraphic framework of the Devonian in Yunnan-Guizhou-Guangxi area, South China

    Directory of Open Access Journals (Sweden)

    Mei Mingxiang

    2013-01-01

    Full Text Available The Caledonian orogeny at the end of the Silurian resulted in great changes in the palaeogeography in the Yunnan-Guizhou-Guangxi area of South China; the continental area of the Early Paleozoic evolved into the extensive Dian-Qian-Gui Sea in the Late Paleozoic. Early in the Devonian, as a result of a major transgression, seawater encroached gradually from the south to the north and clastic facies were deposited. Carbonate deposition was then established in the Yunnan-Guizhou-Guangxi area, with a palaeogeography marked by attached platforms, isolated platforms and narrow basins. As a result of the Ziyun movement towards the end of the Devonian, the Upper Devonian strata are regressive and thin out from the open-sea to the land areas. A study of the nature and distribution of sedimentary facies in space and time recognises 13 third-order sequences in the Devonian strata in Yunnan-Guizhou-Guangxi area, and these form two second-order sequences. The strata of the Lower Devonian comprise 5 third-order sequences (SQ1 to SQ5, which are dominated by transgressive clastics. 4 third-order sequences (SQ6 to SQ9 in the Middle Devonian are characterized by alternations of transgressive clastics and highstand carbonates. In the Upper Devonian, carbonates constitute 4 third-order sequences (SQ10 to SQ13, which are generally marked by the transgressive limestones and highstand dolomites. On the basis of earlier biostratigraphic studies, sea-level changes represented by the third-order sequences with their different facies successions are explored, and the sequence stratigraphic framework is established. Therefore, the Devonian strata in the study area provide an example for further understanding of depositional trends within the sequence-stratigraphic framework.

  19. Late Quaternary pollen data collection and application in land-cover reconstruction for East Asia and Siberia

    Science.gov (United States)

    Cao, Xianyong; Tian, Fang; Ni, Jian; Herzschuh, Ulrike

    2016-04-01

    The various climatic systems and vegetation zones in the East Asia cause the numerous open questions concerning the evolution of the Asian Monsoon and vegetation change on various time-scales. Fossil pollen is one of the most spatially extensive terrestrial palaeoenvironmental proxies during the late Quaternary, and the multi-record fossil pollen synthesis is a potential solution for the open questions in palaeoecology and palaeoclimatology. We collected and selected 274 pollen records from eastern continental Asia (70°135°E and 18°55°N). After pollen percentage recalculations, taxonomic homogenization, age-depth model revision, and pollen abundance linear interpolation, a taxonomically harmonized and temporally standardized fossil pollen dataset established at a 500-year resolution covering the last 22 ka. In addition, we also established a modern pollen dataset including 2626 modern pollen data from China and Mongolia. We used the calibration-set based on modern pollen and satellite-based Advanced Very High Resolution Radiometer (AVHRR) observations of woody cover, to reconstruct woody cover for the 274 fossil pollen records. The spatial range of forest has not noticeably changed in eastern continental Asia during the last 22 ka, although woody cover has, especially at the margin of the eastern Tibetan Plateau and in the forest-steppe transition area of north-central China. Vegetation was sparse during the LGM in the present forested regions, but woody cover increased markedly at the beginning of the Bølling/Allerød period (B/A; ca. 14.5 ka BP) and again at the beginning of the Holocene (ca. 11.5 ka BP), and is related to the enhanced strength of the East Asian Summer Monsoon. Forest flourished in the mid-Holocene (ca. 8 ka BP) possibly due to favourable climatic conditions. In contrast, cover was stable in southern China (high cover) and arid central Asia (very low cover) throughout the investigated period. Forest cover increased in the north

  20. Biostratigraphy of the Middle and Upper Pleistocene of the Caspian Region

    Science.gov (United States)

    Khomchenko, D.; Yanina, T.

    2012-04-01

    Biostratigraphy of the Caspian Pleistocene is based on changes in evolutionary patterns and ecological assemblage change of the mollusk genus Didacna Eichwald. The study of peculiarities and patterns in the spatial-temporal distribution of shells of the genus Didacna in the deposits of the middle and upper Pleistocene of the Caspian region showed, that the molluscan fauna represent a complex hierarchical system of assemblages with different composition and at different taxonomic levels: faunas, complexes, subcomplexes, associations, distinguished following particular criteria. Based on molluscan fauna, namely on distinguished faunal units at different hierarchical levels, we built a regional biostratigraphic (ecostratigraphic) scheme of the Middle and Upper Pleistocene (Neopleistocene according to Russian stratigraphic sheme) of the Caspian, supplementing and specifying the exisiting schemes. Caspian Middle and Upper Pleistocene (Neopleistocene) represent a Didacna biozone - deposits encompassing the entire stratigraphic interval of this taxon distribution. Based on temporal distribution of faunas, the zone is subdivided into subzones, which become the biostratigraphic basis for establishment of horizons: Baku, Urunjik, low Khazar, upper Khazar, Khvalynian and New Caspian. From the point of view of palaeogeography these horizons correspond to transgressive epochs with the same names in the Caspian history, which resulted in accumulation of sediment complexes, filled with particular paleontological material - mollusk faunas. Interval-zones, characterized by faunal complexes, are used for distinguishing subhorizons. From the point of view of palaeogeography they correspond to major transgressive stages, separated by regressions, within the transgressive epochs, which is reflected in the sediment structure and presence of distinguishing mollusk complexes. The subhorizons reflect three transgressive stages during Early Khazar epoch, two transgressive stages during Late

  1. Paleoclimatological revision of climate evolution in Spain since the middle pleistocene from travertine and speleothems studies; Aportaciones al conociiento de la evolucion paleoclimatica y paleoambiental en la pensinsula iberica durante los dos ultimos millones de anos a partir del estudio de travertinos y espeleotemas

    Energy Technology Data Exchange (ETDEWEB)

    Torres, T.; Barettino, D.; Canoira, L.; Cobo, R.; Garcia-Cortes, A.; Grun, R.; Hoyos, M.; Julia, R.; Llamas, R.

    1996-10-01

    This paper deals on the main results of the Project: ``Paleoclimatological revision since the Middle Pleistocene from geochronological and isotope analysis of spanish travertine`` (CEC-F12W-CT91-0075 ``Paleoclimatological revision of climate evolution in the Western Mediterranean Region, evaluation of altered scenarios). Four travertine deposition areas and a karstic zone were selected according to their geographical signification. Travertine deposits areas were: Priego and Rio Blanco: fluvial travertine; Banyoles and Rio Blanco: lacustrine deposits; Tolox: Alluvial fan deposits. The Cueva del Reguerillo was the karstic area selected. In spite of travertine and speleothems are warm climate indicators, important paleoenvironmental and palaeoclimatological data were obtained, which are in short: Through geomorphology and dating (palaeomagnetism, U/Th, Electro spin resonance and amino acid racemization analysis) the fluvial history of Priego, Rio Blanco and el Reguerillo cave, where a neotectonic and palaeosismicity phenomena were also dated. The oldest ESR dating method age obtained was of 950ka; and the oldest Priego deposits AARD dated were 750 ka old. Through dating, sedimentology, stable isotope analysis and palinology some aspects of climatic evolution of the Iberian Peninsula were determined. A net correlation found between palinology and stable isotope ratios in the Banyoles lake drill hole, allowed to validate the results. Some cualitative data on fluvial and karstic systems water input were determined also.

  2. Saponaria pumila (caryophyllaceae) and the ice age in the European alps.

    Science.gov (United States)

    Tribsch, Andreas; Schönswetter, Peter; Stuessy, Tod F

    2002-12-01

    The polymerase chain reaction (PCR)-based amplified fragment length polymorphism (AFLP) technique was applied to elucidate the glacial history of the alpine cushion plant Saponaria pumila in the European Alps. Special emphasis was given to a dense sampling of populations. Our data support a survival of S. pumila during the last ice age in at least three refugia, which are characterized by unique marker sets. Patterns of genetic diversity and divergence can be explained by survival in peripheral refugia and additional in situ survival within the ice sheet on peripheral nunataks. A nunatak survival in interior parts of the Alps needs not be postulated to explain our results. The level of genetic diversity is dramatically different between populations (Shannon's diversity index: 0.87-19.86). Some peripheral populations are characterized by a high number of rare fragments indicating long isolation, but not necessarily by a high level of genetic diversity. Parts of the present distributional area were recolonized via recent long-distance dispersal, leading to severely bottlenecked populations lacking private or rare fragments. The combination of our data with palaeogeological and palaeoclimatological evidence allows us to confine Pleistocene refugia to certain regions and to draw a detailed scenario of the glacial and postglacial history of S. pumila.

  3. Taphonomy of deciduous leaves and changes in the d13C signal after deposition in fresh water settings

    Science.gov (United States)

    Reimann, Simon; Roth-Nebelsick, Anita; Nebelsick, James; Grein, Michaela

    2016-04-01

    Carbon isotopic signals from fossil plant material are an important source of information for palaeoecology and palaeoclimatology. Usually, the 13C isotope is depleted in plant material, compared to the atmospheric 13C content, because 13C is discriminated against 12C during the process of photosynthesis. The degree of 13C discrimination depends on the photosynthetic pathway (C3, C4 and CAM) and is substantially affected by environmental factors (for example, water stress). Various plant material components, however, differ also with respect to their 13C content. It is generally assumed that the d13C signal found in fossil plants reflects that of the living plant to a sufficient degree. Obtaining information on possible alterations during the taphonomic process is, however, desirable. In this study, changes in d13C of deciduous leaves are monitored, from the living leaf still attached to the tree to leaves deposited in fresh water setting for one or more years, thus focusing on early stages of taphonomy. The considered taxa are species from Quercus (oak) and Fagus (beech). Deposited leaves from three fresh water environments in Southwestern Germany were studied: active stream in a forest, still water pond in a forest, and a waterlogged moor environment. Additionally to the isotope measurements, the degree of leaf tissue degradation and colonization with degrading organisms were observed with Scanning Electron Microscopy.

  4. Multiple origins of large hummock deposits in Alai Valley, Northern Pamir: Implications for palaeoclimate reconstructions

    Science.gov (United States)

    Reznichenko, N. V.; Andrews, G. R.; Geater, R. E.; Strom, A.

    2017-05-01

    This paper interprets the origin of several of the largest hummocky landform assemblages in the Alai Valley, Northern Pamir - a formerly glaciated intermontane depression. The vast hummocky deposits in the Koman-Suu and Achik-Tash river catchments are found to be of two contrasting modes of formation: glacial hummocks deposited during Koman and Lenin Glaciers withdraw and avalanche hummocks produced during catastrophic Koman and Lenin rock avalanches. The origins of the deposits we assessed through remote and field-based geomorphological mapping, as well as sedimentological investigations, which included clast analysis and the identification of micro-scale agglomerates indicative of rock avalanche emplacement. Both the Koman and Lenin rock avalanches were large, catastrophic events (with run-outs of 34 and 24 km, respectively, and a volume over 1 × 109 m3 each) that occurred subsequent to glacier withdrawal from the area. The complex conditions on the moment of the rock avalanche emplacement promoted unusual deposits geomorphology and extensive run-outs. The landslide landforms formed over the pre-existing glacial hummocks and fluvial deposits, and are geomorphologically and sedimentologically distinct from the larger glacial hummocks. The reconstruction of this sequence of events has implications for how hummock dating should be interpreted. This research illustrates large scale catastrophic landsliding in the glacial environment, and adds to the ongoing debate about the misidentification of rock avalanche deposits as of glacial origin, and their relevance to palaeoclimatological and palaeoseismological reconstructions.

  5. The dynamic relationship between temperate and tropical circulation systems across South Africa since the last glacial maximum

    Science.gov (United States)

    Chase, Brian M.; Chevalier, Manuel; Boom, Arnoud; Carr, Andrew S.

    2017-10-01

    A fundamental and long-standing question of southern African palaeoclimatology is the way tropical and temperate climate system dynamics have influenced rainfall regimes across the subcontinent since the Last glacial maximum. In this paper, we analyse a selection of recently published palaeoclimate reconstructions along a southwest-northeast transect across South Africa. These records span the last 22,000 years, and encompass the transition between the region's winter and summer rainfall zones. In synthesis, these records confirm broad elements of the dominant paradigm, which proposes an inverse coeval relationship between temperate and tropical systems, with increased precipitation in the winter (summer) rainfall zone during glacial (interglacial) periods. Revealed, however, is a substantially more complex dynamic, with millennial-scale climate change events being strongly - even predominantly - influenced by the interaction and combination of temperate and tropical systems. This synoptic forcing can create same sign anomalies across the South African rainfall zones, contrary to expectations based on the classic model of phase opposition. These findings suggest a new paradigm for the interpretation of southern African palaeoenvironmental records that moves beyond simple binary or additive influences of these systems.

  6. Warming and Cooling: The Medieval Climate Anomaly in Africa and Arabia

    Science.gov (United States)

    Lüning, Sebastian; Gałka, Mariusz; Vahrenholt, Fritz

    2017-11-01

    The Medieval Climate Anomaly (MCA) is a well-recognized climate perturbation in many parts of the world, with a core period of 1000-1200 Common Era. Here we present a palaeotemperature synthesis for the MCA in Africa and Arabia, based on 44 published localities. The data sets have been thoroughly correlated and the MCA trends palaeoclimatologically mapped. The vast majority of available Afro-Arabian onshore sites suggest a warm MCA, with the exception of the southern Levant where the MCA appears to have been cold. MCA cooling has also been documented in many segments of the circum-Africa-Arabian upwelling systems, as a result of changes in the wind systems which were leading to an intensification of cold water upwelling. Offshore cores from outside upwelling systems mostly show warm MCA conditions. The most likely key drivers of the observed medieval climate change are solar forcing and ocean cycles. Conspicuous cold spikes during the earliest and latest MCA may help to discriminate between solar (Oort Minimum) and ocean cycle (Atlantic Multidecadal Oscillation, AMO) influence. Compared to its large share of nearly one quarter of the world's landmass, data from Africa and Arabia are significantly underrepresented in global temperature reconstructions of the past 2,000 years. Onshore data are still absent for most regions in Africa and Arabia, except for regional data clusters in Morocco, South Africa, the East African Rift, and the Levant coast. In order to reconstruct land palaeotemperatures more robustly over Africa and Arabia, a systematic research program is needed.

  7. Peat humification and climate change: a multi-site comparison from mires in south-east Alaska

    Directory of Open Access Journals (Sweden)

    R.J. Payne

    2008-11-01

    Full Text Available Peatland records of Holocene palaeoclimate have been widely used in Europe. Their potential in western North America remains largely unexploited despite an abundance of candidate sites. Peat humification analysis is a widely used technique for palaeoclimatic inference from peatlands. This study attempts to demonstrate a climatic role in determining peat humification by comparing low-resolution peat humification records from five mires in south-east Alaska. Humification was determined by alkali extraction and colorimetry and records dated by radiocarbon and tephrochronology. Testate amoebae analysis was carried out across a major humification-inferred wet shift in three of the sites. The humification results show variability down the length of the cores but there is only limited agreement between records from different sites. Many general trends in the data appear to be out of phase and periods of proxy 'complacency' are shown. This study does not provide strong evidence for climatic forcing of humification in these sites. Methodological issues including possible problems with the age-depth models and the role of a peat-forming plant species signal in the humification data are discussed. The results support previous studies in suggesting the value of employing a multi-proxy, multi-site, and possibly multi-core approach in peat-based palaeoclimatology.

  8. Geochemistry and Sm-Nd systematics of the 1.67 Ga Buanji Group of southwestern Tanzania: Paleo-weathering, provenance and paleo-tectonic setting implications

    Directory of Open Access Journals (Sweden)

    Charles H. Kasanzu

    2017-09-01

    The lower Buanji Formation yielded a depleted mantle Nd model age (TDM of ∼2100 Ma which indicates an Eburnean parentage. TDM ages of 2486–2155 Ma and 2535–2379 Ma obtained from middle and upper Buanji formations, respectively, suggest a progressive increase of sedimentary input from the Tanzania Craton up-stratigraphy. The Eburnean TDM ages of the lower Buanji rocks are attributed to their derivation through denudation of a decaying topographic high composed predominantly of rocks that were generated during the Palaeoproterozoic Ubendian orogenesis, possibly in the realm of Columbian Supercontinent assembly. Overlapping TDM ages between the middle and upper Buanji formations suggest multiple sources involving mixing of detritus from Archaean cratonic rocks and the Palaeoproterozoic Ubendian belt. However, the Archaean signal is relatively more pronounced in the upper Buanji Formation, suggesting sediments derivation from the craton, to the north of the basin. The middle Buanji Formation suggests more diverse protolith, given the relatively larger spread in the TDM ages. The Nb/Ta, Zr/Sm and Ce/Pb ratios coupled with the negative Nb and Ta anomalies, relative to primitive mantle, suggest that the tectonic setting of the source rocks for the Buanji sediments was a subduction zone akin to that generating modern Island Arc Basalts. Thus, we suggest that the Buanji's palaeogeography is consistent with an extensional continental backarc basin during the late Paleoproterozoic.

  9. Provenance and palaeogeographic implications of Eocene-Oligocene sedimentary rocks in the northwestern Basin and Range

    Science.gov (United States)

    Egger, A.E.; Colgan, J.P.; York, C.

    2009-01-01

    A thick sequence of uppermost Eocene to lower Oligocene volcaniclastic and sedimentary rocks is exposed at the base of the Warner Range in northeastern California. This isolated exposure provides insight into the palaeogeographic setting of the northwestern Basin and Range during this time period. Significant thinning of the unit over 35km of lateral exposure and predominantly volcanic clast compositions suggest that the sequence was deposited in an alluvial plain adjacent to a volcanic arc. Palaeocurrent indicators in the conglomerates define a NNE transport direction. Detrital zircon analysis on coarse sandstones and dating of individual granite cobbles show a range of ages consistent with a local, volcanic source area primarily from the SSW with some far-travelled input from northern Nevada; the far-travelled component increases in influence as the unit thins to the north. Comparison with other sedimentary sequences of Eocene age and integration with palaeofloral and geophysical data help to define drainage divides, and suggest that this sequence accumulated in a relatively isolated, intra-arc basin. This localized accumulation differs markedly from contemporaneous drainages to the south that transported material westwards from central Nevada to the palaeoshoreline, and suggests that ongoing volcanism had a strong influence on palaeogeography in this region during the Eocene and Oligocene.

  10. Words of the Editor-in-Chief — Academic discussion is an effective measure to promote scientific development

    Directory of Open Access Journals (Sweden)

    Zeng-Zhao Feng

    2017-07-01

    Full Text Available Van Loon et al.'s paper “The response of stromatolites to seismic shocks: Tomboliths from the Palaeoproterozoic Chaibasa Formation, E India” with a new term “tomboliths” and original viewpoints should be published, but some contents need to be discussed. Shanmugam's paper “The response of stromatolites to seismic shocks: Tomboliths from the Palaeoproterozoic Chaibasa Formation, E India: Discussion and liquefaction basics” pointed out some queries and problems about Van Loon et al.'s paper. It is an academic discussion paper and should be published as well. However, some main problems, such as the new term “tomboliths” and its origin of seismic shocks, “whether stromatolites or tomboliths are soft-sediment deformation structures or not”, etc., also need to be discussed. Academic discussion is an effective measure to promote scientific development. The more thorough academic discussions are carried out regarding academic problems, the more scientific facts and truths will become clear. All participants in this discussion are contributors. It is active to carry out the policy of “A hundred flowers blossom and a hundred schools of thought contend” by our Journal of Palaeogeography.

  11. Large-scale features of Pliocene climate: results from the Pliocene Model Intercomparison Project

    Directory of Open Access Journals (Sweden)

    A. M. Haywood

    2013-01-01

    Full Text Available Climate and environments of the mid-Pliocene warm period (3.264 to 3.025 Ma have been extensively studied. Whilst numerical models have shed light on the nature of climate at the time, uncertainties in their predictions have not been systematically examined. The Pliocene Model Intercomparison Project quantifies uncertainties in model outputs through a coordinated multi-model and multi-model/data intercomparison. Whilst commonalities in model outputs for the Pliocene are clearly evident, we show substantial variation in the sensitivity of models to the implementation of Pliocene boundary conditions. Models appear able to reproduce many regional changes in temperature reconstructed from geological proxies. However, data/model comparison highlights that models potentially underestimate polar amplification. To assert this conclusion with greater confidence, limitations in the time-averaged proxy data currently available must be addressed. Furthermore, sensitivity tests exploring the known unknowns in modelling Pliocene climate specifically relevant to the high latitudes are essential (e.g. palaeogeography, gateways, orbital forcing and trace gasses. Estimates of longer-term sensitivity to CO2 (also known as Earth System Sensitivity; ESS, support previous work suggesting that ESS is greater than Climate Sensitivity (CS, and suggest that the ratio of ESS to CS is between 1 and 2, with a "best" estimate of 1.5.

  12. The DeepMIP Contribution to PMIP4: Experimental Design for Model Simulations of the EECO, PETM, and pre-PETM (version 1.0)

    Science.gov (United States)

    Lunt, Daniel J.; Huber, Matthew; Anagnostou, Eleni; Baatsen, Michiel L. J.; Caballero, Rodrigo; DeConto, Rob; Dijkstra, Henk A.; Donnadieu, Yannick; Evans, David; Feng, Ran; hide

    2017-01-01

    Past warm periods provide an opportunity to evaluate climate models under extreme forcing scenarios, in particular high ( greater than 800 ppmv) atmospheric CO2 concentrations. Although a post hoc intercomparison of Eocene (approximately 50 Ma) climate model simulations and geological data has been carried out previously, models of past high-CO2 periods have never been evaluated in a consistent framework. Here, we present an experimental design for climate model simulations of three warm periods within the early Eocene and the latest Paleocene (the EECO, PETM, and pre-PETM). Together with the CMIP6 pre-industrial control and abrupt 4(times) CO2 simulations, and additional sensitivity studies, these form the first phase of DeepMIP - the Deep-time Model Intercomparison Project, itself a group within the wider Paleoclimate Modeling Intercomparison Project (PMIP). The experimental design specifies and provides guidance on boundary conditions associated with palaeogeography, greenhouse gases, astronomical configuration, solar constant, land surface processes, and aerosols. Initial conditions, simulation length, and output variables are also specified. Finally, we explain how the geological data sets, which will be used to evaluate the simulations, will be developed.

  13. Intra-oceanic subduction shaped the assembly of Cordilleran North America.

    Science.gov (United States)

    Sigloch, Karin; Mihalynuk, Mitchell G

    2013-04-04

    The western quarter of North America consists of accreted terranes--crustal blocks added over the past 200 million years--but the reason for this is unclear. The widely accepted explanation posits that the oceanic Farallon plate acted as a conveyor belt, sweeping terranes into the continental margin while subducting under it. Here we show that this hypothesis, which fails to explain many terrane complexities, is also inconsistent with new tomographic images of lower-mantle slabs, and with their locations relative to plate reconstructions. We offer a reinterpretation of North American palaeogeography and test it quantitatively: collision events are clearly recorded by slab geometry, and can be time calibrated and reconciled with plate reconstructions and surface geology. The seas west of Cretaceous North America must have resembled today's western Pacific, strung with island arcs. All proto-Pacific plates initially subducted into almost stationary, intra-oceanic trenches, and accumulated below as massive vertical slab walls. Above the slabs, long-lived volcanic archipelagos and subduction complexes grew. Crustal accretion occurred when North America overrode the archipelagos, causing major episodes of Cordilleran mountain building.

  14. The palaeogeographic setting and the local environmental impact of the 130 ka Falconiera tuff-cone eruption (Ustica island, Italy)

    Science.gov (United States)

    de Vita, Sandro; Foresta Martin, Franco

    2017-04-01

    This research focuses on the effects of the last eruption at Ustica (Suthern Tyrrhenian Sea, Italy), which formed the Falconiera tuff-cone at around 130 ka BP in the north-eastern tip of the island. This eruption was mainly explosive and phreatomagmatic, and emplaced a series of pyroclastic surge beds that formed an asymmetric tuff cone. This is the most easily recognizable volcanic edifice on Ustica, although its north-eastern sector has been partially eroded. A section of the feeding conduit is exposed northward, and is composed of lavas that fed the last stages of the eruption characterized by an intracrateric lava lake and a Strombolian scoria-fallout deposit. The eruption occurred during Upper Pleistocene Marine Isotopic Substage 5.5, a warm period characterized by a high sea-level stand (6±3 m above the present sea level in stable areas) and the diffusion of subtropical flora and fauna across the Mediterranean sea. This eruption slightly modified the morphology of Ustica, but impacted both marine and terrestrial environments, burying beach deposits rich in mollusk shells (i.e. Strombus bubonius, Conus testudinarius, Brachidontes puniceus), colonies of corals (Cladocora caespitosa) and subaerial plants (Chamaerops humilis). These organisms, found in some cases in their life position, along with other lines of evidence, provide information on the palaeogeography of this sector of the island at the time of the eruption, and on the local impact of this event on the environment.

  15. Ordovician conodonts of the Tarim Region, Xinjiang, China: Occurrence and use as paleoenvironment indicators

    Science.gov (United States)

    Zhi-hao, Wang; Yu-ping, Qi; Bergström, Stig M.

    2007-03-01

    A review of the distribution of different Ordovician conodont faunas in eight areas of the Tarim Region shows that these conodont faunas can be classified into the North China and South China types. The North China type is characterized by Aurilobodus leptosomatus, A. aurilobodus, A. simplex, Tangshanodus tanshanensis, Loxodus dissectus, Parasseratognathus paltodiformis, Microcoelodus symmetricus, Belodina compressa, B. confluens, Pseudobelodina dispansa, Yaoxianognathus yaoxianensis, and Taoqupognathus blandus. These were adapted to shallow, warm-water environments. The South China type is represented by the genera Amorphognathus, Baltoniodus, Cahabagnathus, Eoplacognathus, Lenodus, Microzarkodina, Oepikodus, Paroistodus, Paracordylodus, Periodon, Polonodus, and Pygodus, which were adapted to outer shelf, deeper, and colder water environments. Using the general pattern of conodont distribution, it is possible to interpret the various depositional environments and to reconstruct broad changes in palaeogeography of the Tarim Region during Ordovician time. In general, during Tremadocian to early Middle Ordovician time, most of the Tarim Region was a shallow semi-restricted platform that became deeper towards the north and east, with an open platform in Kalping and in the northern part of Taklimakan Desert. A slope and deep basin existed in the current Tianshan Mountains region. The Tarim sea was shallow during the Early Ordovician and became deeper during "Caradocian" (Sandbian and Early Katian) time, to become shallow again during "Ashgillian" (Late Katian) time, with the exception of part of central Taklimakan, which was a land area during "Caradocian" (Sandbian and Early Katian) time.

  16. A living fossil tale of Pangaean biogeography.

    Science.gov (United States)

    Murienne, Jerome; Daniels, Savel R; Buckley, Thomas R; Mayer, Georg; Giribet, Gonzalo

    2014-01-22

    The current distributions of widespread groups of terrestrial animals and plants are supposedly the result of a mixture of either vicariance owing to continental split or more recent trans-oceanic dispersal. For organisms exhibiting a vicariant biogeographic pattern-achieving their current distribution by riding on the plates of former supercontinents-this view is largely inspired by the belief that Pangaea lacked geographical or ecological barriers, or that extinctions and dispersal would have erased any biogeographic signal since the early Mesozoic. We here present a time-calibrated molecular phylogeny of Onychophora (velvet worms), an ancient and exclusively terrestrial panarthropod group distributed throughout former Pangaean landmasses. Our data not only demonstrate that trans-oceanic dispersal does not need be invoked to explain contemporary distributions, but also reveal that the early diversification of the group pre-dates the break-up of Pangaea, maintaining regionalization even in landmasses that have remained contiguous throughout the history of the group. These results corroborate a growing body of evidence from palaeontology, palaeogeography and palaeoclimatic modelling depicting ancient biogeographic regionalization over the continuous landmass of Pangaea.

  17. The DeepMIP contribution to PMIP4: experimental design for model simulations of the EECO, PETM, and pre-PETM (version 1.0)

    Science.gov (United States)

    Lunt, Daniel J.; Huber, Matthew; Anagnostou, Eleni; Baatsen, Michiel L. J.; Caballero, Rodrigo; DeConto, Rob; Dijkstra, Henk A.; Donnadieu, Yannick; Evans, David; Feng, Ran; Foster, Gavin L.; Gasson, Ed; von der Heydt, Anna S.; Hollis, Chris J.; Inglis, Gordon N.; Jones, Stephen M.; Kiehl, Jeff; Kirtland Turner, Sandy; Korty, Robert L.; Kozdon, Reinhardt; Krishnan, Srinath; Ladant, Jean-Baptiste; Langebroek, Petra; Lear, Caroline H.; LeGrande, Allegra N.; Littler, Kate; Markwick, Paul; Otto-Bliesner, Bette; Pearson, Paul; Poulsen, Christopher J.; Salzmann, Ulrich; Shields, Christine; Snell, Kathryn; Stärz, Michael; Super, James; Tabor, Clay; Tierney, Jessica E.; Tourte, Gregory J. L.; Tripati, Aradhna; Upchurch, Garland R.; Wade, Bridget S.; Wing, Scott L.; Winguth, Arne M. E.; Wright, Nicky M.; Zachos, James C.; Zeebe, Richard E.

    2017-02-01

    Past warm periods provide an opportunity to evaluate climate models under extreme forcing scenarios, in particular high ( > 800 ppmv) atmospheric CO2 concentrations. Although a post hoc intercomparison of Eocene ( ˜ 50 Ma) climate model simulations and geological data has been carried out previously, models of past high-CO2 periods have never been evaluated in a consistent framework. Here, we present an experimental design for climate model simulations of three warm periods within the early Eocene and the latest Paleocene (the EECO, PETM, and pre-PETM). Together with the CMIP6 pre-industrial control and abrupt 4 × CO2 simulations, and additional sensitivity studies, these form the first phase of DeepMIP - the Deep-time Model Intercomparison Project, itself a group within the wider Paleoclimate Modelling Intercomparison Project (PMIP). The experimental design specifies and provides guidance on boundary conditions associated with palaeogeography, greenhouse gases, astronomical configuration, solar constant, land surface processes, and aerosols. Initial conditions, simulation length, and output variables are also specified. Finally, we explain how the geological data sets, which will be used to evaluate the simulations, will be developed.

  18. Fossil climbing perch and associated plant megafossils indicate a warm and wet central Tibet during the late Oligocene.

    Science.gov (United States)

    Wu, Feixiang; Miao, Desui; Chang, Mee-Mann; Shi, Gongle; Wang, Ning

    2017-04-13

    Understanding the Tibetan Plateau's palaeogeography and palaeoenvironment is critical for reconstructing Asia's climatic history; however, aspects of the plateau's uplift history remain unclear. Here, we report a fossil biota that sheds new light on these issues. It comprises a fossil climbing perch (Anabantidae) and a diverse subtropical fossil flora from the Chattian (late Oligocene) of central Tibet. The fish, Eoanabas thibetana gen. et sp. nov., is inferred to be closely related to extant climbing perches from tropical lowlands in south Asia and sub-Saharan Africa. It has osteological correlates of a labyrinth organ, which in extant climbing perches gives them the ability to breathe air to survive warm, oxygen-poor stagnant waters or overland excursion under moist condition. This indicates that Eoanabas likewise lived in a warm and humid environment as suggested by the co-existing plant assemblage including palms and golden rain trees among others. As a palaeoaltimeter, this fossil biota suggests an elevation of ca. 1,000 m. These inferences conflict with conclusions of a high and dry Tibet claimed by some recent and influential palaeoaltimetry studies. Our discovery prompts critical re-evaluation of prevailing uplift models of the plateau and their temporal relationships with the Cenozoic climatic changes.

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

    Science.gov (United States)

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

    2013-01-01

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

  20. Review of research in internal-wave and internal-tide deposits of China: Discussion

    Directory of Open Access Journals (Sweden)

    G. Shanmugam

    2014-10-01

    Full Text Available This discussion of a review article by [27], published in the Journal of Palaeogeography (2(1: 56– 65, is aimed at illustrating that interpretations of ten ancient examples in China and one in the central Appalachians (USA as deep-water deposits of internal waves and internal tides are unsustainable. This critical assessment is based on an in-depth evaluation of oceanographic and sedimentologic data on internal waves and internal tides derived from 332 print and online published works during 1838–January 2013, which include empirical data on the physical characteristics of modern internal waves and internal tides from 51 regions of the world’s oceans [108]. In addition, core and outcrop descriptions of deep-water strata from 35 case studies worldwide carried out by the author during 1974–2011, and a selected number of case studies published by other researchers are evaluated for identifying the sedimentological challenges associated with distinguishing types of bottom-current reworked sands in the ancient sedimentary record. The emerging conclusion is that any interpretation of ancient strata as deposits of internal waves and internal tides is premature.

  1. An analysis of dinosaurian biogeography: evidence for the existence of vicariance and dispersal patterns caused by geological events.

    Science.gov (United States)

    Upchurch, Paul; Hunn, Craig A; Norman, David B

    2002-03-22

    As the supercontinent Pangaea fragmented during the Mesozoic era, dinosaur faunas were divided into isolated populations living on separate continents. It has been predicted, therefore, that dinosaur distributions should display a branching ('vicariance') pattern that corresponds with the sequence and timing of continental break-up. Several recent studies, however, minimize the importance of plate tectonics and instead suggest that dispersal and regional extinction were the main controls on dinosaur biogeography. Here, in order to test the vicariance hypothesis, we apply a cladistic biogeographical method to a large dataset on dinosaur relationships and distributions. We also introduce a methodological refinement termed 'time-slicing', which is shown to be a key step in the detection of ancient biogeographical patterns. These analyses reveal biogeographical patterns that closely correlate with palaeogeography. The results provide the first statistically robust evidence that, from Middle Jurassic to mid-Cretaceous times, tectonic events had a major role in determining where and when particular dinosaur groups flourished. The fact that evolutionary trees for extinct organisms preserve such distribution patterns opens up a new and fruitful direction for palaeobiogeographical research.

  2. Fossil evidence for the early ant evolution

    Science.gov (United States)

    Perrichot, Vincent; Lacau, Sébastien; Néraudeau, Didier; Nel, André

    2008-02-01

    Ants are one of the most studied insects in the world; and the literature devoted to their origin and evolution, systematics, ecology, or interactions with plants, fungi and other organisms is prolific. However, no consensus yet exists on the age estimate of the first Formicidae or on the origin of their eusociality. We review the fossil and biogeographical record of all known Cretaceous ants. We discuss the possible origin of the Formicidae with emphasis on the most primitive subfamily Sphecomyrminae according to its distribution and the Early Cretaceous palaeogeography. And we review the evidence of true castes and eusociality of the early ants regarding their morphological features and their manner of preservation in amber. The mid-Cretaceous amber forest from south-western France where some of the oldest known ants lived, corresponded to a moist tropical forest close to the shore with a dominance of gymnosperm trees but where angiosperms (flowering plants) were already diversified. This palaeoenvironmental reconstruction supports an initial radiation of ants in forest ground litter coincident with the rise of angiosperms, as recently proposed as an ecological explanation for their origin and successful evolution.

  3. A question of time: the land snail Murella muralis (Gastropoda: Pulmonata) reveals constraints on past ecological speciation.

    Science.gov (United States)

    Fiorentino, V; Manganelli, G; Giusti, F; Tiedemann, R; Ketmaier, V

    2013-01-01

    The lively debate about speciation currently focuses on the relative importance of factors driving population differentiation. While many studies are increasingly producing results on the importance of selection, little is known about the interaction between drift and selection. Moreover, there is still little knowledge on the spatial-temporal scales at which speciation occurs, that is, arrangement of habitat patches, abruptness of habitat transitions, climate and habitat changes interacting with selective forces. To investigate these questions, we quantified variation on a fine geographical scale analysing morphological (shell) and genetic data sets coupled with environmental data in the land snail Murella muralis, endemic to the Mediterranean island of Sicily. Analysis of a fragment of the mitochondrial DNA cytochrome oxidase I gene (COI) and eight nuclear microsatellite loci showed that genetic variation is highly structured at a very fine spatial scale by local palaeogeographical events and historical population dynamics. Molecular clock estimates, calibrated here specifically for Tyrrhenian land snails, provided a framework of palaeogeographical events responsible for the observed geographical variations and migration routes. Finally, we showed for the first time well-documented lines of evidence of selection in the past, which explains divergence of land snail shell shapes. We suggest that time and palaeogeographical history acted as constraints in the progress along the ecological speciation continuum. Our study shows that testing for correlation among palaeogeography, morphology and genetic data on a fine geographical scale provides information fundamental for a detailed understanding of ecological speciation processes. © 2012 Blackwell Publishing Ltd.

  4. Mesozoic and Eocene ductile deformation of western Central Iran: from Cimmerian collisional orogeny to Eocene extension and exhumation

    Science.gov (United States)

    Kargaranbafghi, Fariba; Neubauer, Franz; Genser, Johann

    2010-05-01

    younger, and plateau ages at 140 and 90 Ma have been found. The new age data from the Boneh Shurow and Posht-e-Badam complexes argue for a distinct history of these two complexes. Taking the model of Bagheri and Stampfli (2008), the Boneh Shurow comples can be placed together with Variscan accretionary complex. Since the benchmark paper of Şengör (1979), the Cimmerian orogeny is considered to represent the suture of Paleo-Tethys. The Cimmerian orogeny is obviously multiphase, and the Posht-e-Badam complex with its Middle Triassic medium-grade metamorphism and granite intrusions record the main stage of plate collision. The significance of the second, much later event at the Jurassic/Cretaceous boundary remains unclear, but it is compressional as the intercalation of the Raetoliassic phyllites records. REFERENCES: 1. Bagheri, S., Stampfli, G. M., 2008. The Anarak, Jandaq and Posht-e-Badam metamorphic complexes in central Iran: New geological data, relationships and tectonic implications. Tectonophysics 451, 123-155. 2. Ramezani, J., Tucker, R., 2003. The Saghand region, Central Iran: U-Pb geochronology, petrogenesis and implication for Gondwana tectonics. American Journal of Science 303, 622-665. 3. Sengör, A.M.C., 1979. Mid-Mesozoic closure of Permo-Triassic Tethys and its implications. Nature 279, 590-593. 4. Verdel, C., Wernicke, B. P., Ramezani, J. Hassanzadeh, J., Renne, P. R., Spell, T. L., 2007. Geology and thermochronology of Tertiary Cordilleran-style metamorphic core complexes in the Saghand region of central Iran. Geol. Soc. Am. Bull 119, 961-977.

  5. Characterization of fluid inclusions and sulfur isotopes in the Iju porphyry copper deposit, North West of Shahr-e-Babak

    Directory of Open Access Journals (Sweden)

    Malihe Golestani

    2017-07-01

    Full Text Available Introduction The Iju porphyry copper deposit is located in the southern part of the Urumieh-Dokhtar magmatic arc (Dehaj-Sarduieh belt within the Kerman copper belt (Dimitrijevic, 1973. The Porphyry Copper mineralization in the Iranian plate occurs dominantly along the Urumieh-Dokhtar arc, which has resulted from the subduction of the Arabian plate beneath the central Iran and the closure of the Neo-Tethys Ocean during the Alpine orogeny (Hassanzadeh, 1993. The Iju porphyry copper deposit with 25 million tons of ore reserves is one of the main copper deposits within the Kerman copper belt. The mining area is composed of upper Miocene volcanic and subvolcanic rocks (mineralized and barren subvolcanic rocks and quaternary deposits. Two hydrothermal alteration zones of quartz-sericite-pyrite and propylitic zones can be identified in the Iju area. The copper mineralization in the Iju deposit occurs as disseminated, stockwork and hydrothermal breccia. In the hypogene zone, the mineral paragenesis include chalcopyrite, pyrite, with minor occurrences of bornite and magnetite. This paper reports geological, mineralogical, fluid inclusion and S isotope data from the Iju deposit in order to investigate ore-bearing fluids’ characteristics and the mechanisms of ore deposition. Materials and methods Fifteen samples of syngenetic quartz+pyrite bearing veinlets within the quartz-sericite-pyrite zone were selected from different depths across the seven boreholes. Quartz was used for double-polished thin sections and pyrite was used for sulfur isotope analysis. Fluid inclusion studies were performed using the Linkam cooling and heating stage, the THMSG 600 model. The syngenetic pyrite with thermometry quartz sample was used for the sulfur isotope experiments. Stable isotope analysis was performed at the Hatch Stable Isotope Laboratory in the University of Ottawa, Canada. Results The fluid inclusions of the Iju deposit represent a wide range in the

  6. New insights from coral growth band studies in an era of rapid environmental change

    Science.gov (United States)

    Lough, Janice M.; Cooper, Timothy F.

    2011-10-01

    The rapid formation of calcium carbonate coral skeletons (calcification) fuelled by the coral-algal symbiosis is the backbone of tropical coral reef ecosystems. However, the efficacy of calcification is measurably influenced by the sea's physico-chemical environment, which is changing rapidly. Warming oceans have already led to increased frequency and severity of coral bleaching, and ocean acidification has a demonstrable potential to cause reduced rates of calcification. There is now general agreement that ocean warming and acidification are attributable to human activities increasing greenhouse gas concentrations in the atmosphere, and the large part of the extra carbon dioxide (the main greenhouse gas) that is absorbed by oceans. Certain massive corals provide historical perspectives on calcification through the presence of dateable annual density banding patterns. Each band is a page in an environmental archive that reveals past responses of growth (linear extension, skeletal density and calcification rate) and provides a basis for prediction of future of coral growth. A second major line of research focuses on the measurement of various geochemical tracers incorporated into the growth bands, allowing the reconstruction of past marine climate conditions (i.e. palaeoclimatology). Here, we focus on the structural properties of the annual density bands themselves (viz. density; linear extension), exploring their utility in providing both perspectives on the past and pointers to the future of calcification on coral reefs. We conclude that these types of coral growth records, though relatively neglected in recent years compared to the geochemical studies, remain immensely valuable aids to unravelling the consequences of anthropogenic climate change on coral reefs. Moreover, an understanding of coral growth processes is an essential pre-requisite for proper interpretation of studies of geochemical tracers in corals.

  7. Last nine-thousand years of temperature variability in Northern Europe

    Directory of Open Access Journals (Sweden)

    H. Seppä

    2009-09-01

    Full Text Available The threat of future global warming has generated a major interest in quantifying past climate variability on centennial and millennial time-scales. However, palaeoclimatological records are often noisy and arguments about past variability are only possible if they are based on reproducible features in several reliably dated datasets. Here we focus on the last 9000 years, explore the results of 36 Holocene pollen-based July mean and annual mean temperature reconstructions from Northern Europe by stacking them to create summary curves, and compare them with a high-resolution, summary chironomid-based temperature record and other independent palaeoclimate records. The stacked records show that the "Holocene Thermal Maximum" in the region dates to 8000 to 4800 cal yr BP and that the "8.2 event" and the "Little Ice Age" at 500–100 cal yr BP are the clearest cold episodes during the Holocene. In addition, a more detailed analysis of the last 5000 years pinpoints centennial-scale climate variability with cold anomalies at 3800–3000 and 500–100 cal yr BP, a long, warmer period around 2000 cal yr BP, and a marked warming since the mid 19th century. The colder (warmer anomalies are associated with increased (decreased humidity over the northern European mainland, consistent with the modern high correlation between cold (warm and humid (dry modes of summer weather in the region. A comparison with the key proxy records reflecting the main forcing factors does not support the hypothesis that solar variability is the cause of the late-Holocene centennial-scale temperature changes. We suggest that the reconstructed anomalies are typical of Northern Europe and their occurrence may be related to the oceanic and atmospheric circulation variability in the North Atlantic – North-European region.

  8. Using Oxygen and Carbon Isotopic Signatures in Order to Infer Climatic and Dietary Information in Roman Edessa, Greece

    Science.gov (United States)

    Michael, Dimitra-Ermioni; Dotsika, Elissavet

    2017-12-01

    as palaeoclimatological and palaeodietary tools respectively.

  9. Modelling tree ring cellulose δ18O variations in two temperature-sensitive tree species from North and South America

    Science.gov (United States)

    Lavergne, Aliénor; Gennaretti, Fabio; Risi, Camille; Daux, Valérie; Boucher, Etienne; Savard, Martine M.; Naulier, Maud; Villalba, Ricardo; Bégin, Christian; Guiot, Joël

    2017-11-01

    Oxygen isotopes in tree rings (δ18OTR) are widely used to reconstruct past climates. However, the complexity of climatic and biological processes controlling isotopic fractionation is not yet fully understood. Here, we use the MAIDENiso model to decipher the variability in δ18OTR of two temperature-sensitive species of relevant palaeoclimatological interest (Picea mariana and Nothofagus pumilio) and growing at cold high latitudes in North and South America. In this first modelling study on δ18OTR values in both northeastern Canada (53.86° N) and western Argentina (41.10° S), we specifically aim at (1) evaluating the predictive skill of MAIDENiso to simulate δ18OTR values, (2) identifying the physical processes controlling δ18OTR by mechanistic modelling and (3) defining the origin of the temperature signal recorded in the two species. Although the linear regression models used here to predict daily δ18O of precipitation (δ18OP) may need to be improved in the future, the resulting daily δ18OP values adequately reproduce observed (from weather stations) and simulated (by global circulation model) δ18OP series. The δ18OTR values of the two species are correctly simulated using the δ18OP estimation as MAIDENiso input, although some offset in mean δ18OTR levels is observed for the South American site. For both species, the variability in δ18OTR series is primarily linked to the effect of temperature on isotopic enrichment of the leaf water. We show that MAIDENiso is a powerful tool for investigating isotopic fractionation processes but that the lack of a denser isotope-enabled monitoring network recording oxygen fractionation in the soil-vegetation-atmosphere compartments limits our capacity to decipher the processes at play. This study proves that the eco-physiological modelling of δ18OTR values is necessary to interpret the recorded climate signal more reliably.

  10. Testing peatland water-table depth transfer functions using high-resolution hydrological monitoring data

    Science.gov (United States)

    Swindles, Graeme T.; Holden, Joseph; Raby, Cassandra L.; Turner, T. Edward; Blundell, Antony; Charman, Dan J.; Menberu, Meseret Walle; Kløve, Bjørn

    2015-07-01

    Transfer functions are now commonly used to reconstruct past environmental variability from palaeoecological data. However, such approaches need to be critically appraised. Testate amoeba-based transfer functions are an established method for the quantitative reconstruction of past water-table variations in peatlands, and have been applied to research questions in palaeoclimatology, peatland ecohydrology and archaeology. We analysed automatically-logged peatland water-table data from dipwells located in England, Wales and Finland and a suite of three year, one year and summer water-table statistics were calculated from each location. Surface moss samples were extracted from beside each dipwell and the testate amoebae community composition was determined. Two published transfer functions were applied to the testate-amoeba data for prediction of water-table depth (England and Europe). Our results show that estimated water-table depths based on the testate amoeba community reflect directional changes, but that they are poor representations of the real mean or median water-table magnitudes for the study sites. We suggest that although testate amoeba-based reconstructions can be used to identify past shifts in peat hydrology, they cannot currently be used to establish precise hydrological baselines such as those needed to inform management and restoration of peatlands. One approach to avoid confusion with contemporary water-table determinations is to use residuals or standardised values for peatland water-table reconstructions. We contend that our test of transfer functions against independent instrumental data sets may be more powerful than relying on statistical testing alone.

  11. Gratkorn: A benchmark locality for the continental Sarmatian s.str. of the Central Paratethys

    Science.gov (United States)

    Gross, M.; Böhme, M.; Prieto, J.

    2011-11-01

    This paper presents one of the richest and most complete vertebrate faunas of the late Middle Miocene (~12 Ma) of Central Europe. Up to now, sixty-two vertebrate taxa, comprising all major groups (fishes, amphibians, reptiles, birds, mammals), have been recorded. Based on sedimentological and palaeobiological evidences, this Fossillagerstätte is assumed to originate from a floodplain paleosol formed on top of a braided river sequence. The fauna points to a highly structured, somewhat vegetated landscape with a wide array of habitats (e.g., fluvial channels, sporadically moist floodplains, short-lived ponds, savannah-like open areas and screes). It was preserved due to a rapid drowning and the switch to a freshwater lake environment. Palaeoclimatological data, derived from pedogenic features as well as from biota, indicate an overall semi-arid, subtropical climate with distinct seasonality (mean annual precipitation 486 ± 252 mm, mean annual temperature ~15°C). This underlines the late Middle/early Late Miocene dry-spell in Central Europe. From taphonomical point of view, the irregularly distributed but roughly associated larger vertebrate remains refer to an in situ accumulation of the bone bed. Splintered bones, gnawing marks as well as rhizoconcretions and root corrosion structures record some pre- and post-burial modification of the taphocoenose. However, the findings of pellet remains argue for a very fast burial and thus to a low degree of time-averaging. For this reason, the fossil fauna reflects the original vertebrate community rather well and is a cornerstone for the understanding of late Middle Miocene terrestrial ecosystems in this region. Certainly, Gratkorn will be one of the key faunas for a high-resolution continental biostratigraphy and the comprehension of Europe's faunal interchanges near the Middle/Late Miocene transition.

  12. The palaeolimnology of northern Lake Malawi over the last 25 ka based upon the elemental and stable isotopic composition of sedimentary organic matter

    Science.gov (United States)

    Filippi, Maria Letizia; Talbot, Michael R.

    2005-05-01

    Sediments accumulating in offshore areas of northern Lake Malawi typically contain 1-4% organic carbon. This organic matter (OM) is of mainly phytoplankton origin with varying mixtures of terrestrial and degraded, reworked material. High-resolution, stable carbon and nitrogen isotopic, elemental and Rock-Eval pyrolysis analyses of the bulk OM contained in three cores have been used to characterise the OM and provide detailed insights into the palaeolimnology and palaeoclimatology of northern Lake Malawi over the last 25 ka. Preservation of the OM as reflected by its Rock-Eval hydrogen index (HI) is highly variable. Periods characterised by notably low HI (trade wind system, and the locus of high primary production at the south end of the lake. Periods of low δN during the mid- and late Holocene suggest intervals of stable stratification due to significantly reduced wind-driven mixing in the northern part of the lake, when N-fixing cyanophytes formed a major component of the phytoplankton. The geochemical data support recent suggestions of lowstand conditions in Lake Malawi at the time of the LGM, and provide additional evidence of periods of intense but localised aridity in the terminal Pleistocene-earliest Holocene and at the time of the Little Ice Age. The change in mixing regime at ca 11.8 ka seems to have been the result of a radical reorganisation of the dominant surface wind flow over south-eastern Africa. The transition was, within the resolution of currently available chronologies, apparently contemporaneous with marked changes in the circulation patterns of adjacent oceans, and the climate of more distant parts of the Northern Hemisphere.

  13. West Coast volcanic ashes provide a new continental-scale Lateglacial isochron

    Science.gov (United States)

    Pyne-O'Donnell, Sean D. F.; Cwynar, Les C.; Jensen, Britta J. L.; Vincent, Jessie H.; Kuehn, Stephen C.; Spear, Ray; Froese, Duane G.

    2016-06-01

    The 'Lateglacial' period (∼14.7-11.7 cal ka BP) eruptions of Mount St Helens and Glacier Peak in the Cascade Range deposited ash layers (tephras) within a short time span across much of western North America where they form event-stratigraphic marker layers or isochrons. They were deposited at a time which has long been of interest because it represents the transition between two fundamental states of the climate system: the late Pleistocene glacial world when ice sheets were widespread, and the modern interglacial Holocene world. This transition was marked by rapid changes in the distribution of plants, animals and humans on the landscape, and is characterised by short, rapid climate reversals in the warming trend. Yet despite the importance of understanding this period for many areas of palaeoclimatology, palaeobotany and archaeology it remains one of the most difficult for which to develop accurate chronologies because of fluctuations in atmospheric radiocarbon concentration. Hence, the occurrences of distinctive tephra isochrons are valuable for chronological control. Here, we report the first detection of the Mount St Helens set J and Glacier Peak tephras as closely-spaced 'cryptotephra' layers (not visible in stratigraphy to the naked eye) in three eastern seaboard lakes and dated to 13.74-13.45 cal ka BP. The presence of these tephras >4000 km from their sources affords an opportunity for continent-wide correlations by providing a high-precision chronological benchmark that is otherwise often lacking in North American studies of palaeoenvironmental change and deglaciation, megafaunal extinction and palaeoindian colonisation.

  14. Trace-element budgets in the Ohio/Sunbury shales of Kentucky: Constraints on ocean circulation and primary productivity in the Devonian-Mississippian Appalachian Basin

    Science.gov (United States)

    Perkins, R.B.; Piper, D.Z.; Mason, C.E.

    2008-01-01

    The hydrography of the Appalachian Basin in late Devonian-early Mississippian time is modeled based on the geochemistry of black shales and constrained by others' paleogeographic reconstructions. The model supports a robust exchange of basin bottom water with the open ocean, with residence times of less than forty years during deposition of the Cleveland Shale Member of the Ohio Shale. This is counter to previous interpretations of these carbon-rich units having accumulated under a stratified and stagnant water column, i.e., with a strongly restricted bottom bottom-water circulation. A robust circulation of bottom waters is further consistent with the palaeoclimatology, whereby eastern trade-winds drove upwelling and arid conditions limited terrestrial inputs of siliciclastic sediment, fresh waters, and riverine nutrients. The model suggests that primary productivity was high (~ 2??g C m- 2 d- 1), although no higher than in select locations in the ocean today. The flux of organic carbon settling through the water column and its deposition on the sea floor was similar to fluxes found in modern marine environments. Calculations based on the average accumulation rate of the marine fraction of Ni suggest the flux of organic carbon settling out of the water column was approximately 9% of primary productivity, versus an accumulation rate (burial) of organic carbon of 0.5% of primary productivity. Trace-element ratios of V:Mo and Cr:Mo in the marine sediment fraction indicate that bottom waters shifted from predominantly anoxic (sulfate reducing) during deposition of the Huron Shale Member of the Ohio Shale to predominantly suboxic (nitrate reducing) during deposition of the Cleveland Shale Member and the Sunbury Shale, but with anoxic conditions occurring intermittently throughout this period. ?? 2008 Elsevier B.V.

  15. Are there pre-Quaternary geological analogues for a future greenhouse warming?

    Science.gov (United States)

    Haywood, Alan M; Ridgwell, Andy; Lunt, Daniel J; Hill, Daniel J; Pound, Matthew J; Dowsett, Harry J; Dolan, Aisling M; Francis, Jane E; Williams, Mark

    2011-03-13

    Given the inherent uncertainties in predicting how climate and environments will respond to anthropogenic emissions of greenhouse gases, it would be beneficial to society if science could identify geological analogues to the human race's current grand climate experiment. This has been a focus of the geological and palaeoclimate communities over the last 30 years, with many scientific papers claiming that intervals in Earth history can be used as an analogue for future climate change. Using a coupled ocean-atmosphere modelling approach, we test this assertion for the most probable pre-Quaternary candidates of the last 100 million years: the Mid- and Late Cretaceous, the Palaeocene-Eocene Thermal Maximum (PETM), the Early Eocene, as well as warm intervals within the Miocene and Pliocene epochs. These intervals fail as true direct analogues since they either represent equilibrium climate states to a long-term CO(2) forcing--whereas anthropogenic emissions of greenhouse gases provide a progressive (transient) forcing on climate--or the sensitivity of the climate system itself to CO(2) was different. While no close geological analogue exists, past warm intervals in Earth history provide a unique opportunity to investigate processes that operated during warm (high CO(2)) climate states. Palaeoclimate and environmental reconstruction/modelling are facilitating the assessment and calculation of the response of global temperatures to increasing CO(2) concentrations in the longer term (multiple centuries); this is now referred to as the Earth System Sensitivity, which is critical in identifying CO(2) thresholds in the atmosphere that must not be crossed to avoid dangerous levels of climate change in the long term. Palaeoclimatology also provides a unique and independent way to evaluate the qualities of climate and Earth system models used to predict future climate.

  16. European climate reconstructed for the past 500 years based on documentary and instrumental evidence

    Science.gov (United States)

    Wheeler, Dennis; Brazdil, Rudolf; Pfister, Christian

    2010-05-01

    European climate reconstructed for the past 500 years based on documentary and instrumental evidence Dennis Wheeler, Rudolf Brázdil, Christian Pfister and the Millennium project SG1 team The paper summarises the results of historical-climatological research conducted as part of the EU-funded 6th FP project MILLENNIUM the principal focus of which was the investigation of European climate during the past one thousand years (http://www.millenniumproject.net/). This project represents a major advance in bringing together, for the first time on such a scale, historical climatologists with other palaeoclimatological communities and climate modellers from many European countries. As part of MILLENNIUM, a sub-group (SG1) of historical climatologists from ten countries had the responsibility of collating and comprehensively analysing evidence from instrumental and documentary archives. This paper presents the main results of this undertaking but confines its attention to the study of the climate of the past 500 years and represents a summary of 10 themed papers submitted for a special issue of Climatic Change. They range across a variety of topics including newly-studied documentary data sources (e.g. early instrumental records, opening of the Stockholm harbour, ship log book data), temperature reconstructions for Central Europe, the Stockholm area and Mediterranean based on different types of documentary evidence, the application of standard paleoclimatological approaches to reconstructions based on index series derived from the documentary data, the influence of circulation dynamics on January-April climate , a comparison of reconstructions based on documentary data with the model runs (ECHO-G), a study of the quality of instrumental data in climate reconstructions, a 500-year flood chronology in Europe, and selected disastrous European windstorms and their reflection in documentary evidence and human memory. Finally, perspectives of historical-climatological research

  17. The rock avalanche sediment in moraines and its implication for palaeoclimate reconstruction

    Science.gov (United States)

    Reznichenko, N.; Davies, T. R. H.; Shulmeister, J.; Winkler, S.

    2012-04-01

    Rock avalanches mobilise a large quantity of sediment that after deposition on a glacier may cause its regime to alter. The glacier response includes change of mass balance after the rock avalanche emplacement followed by re-deposition of the rock avalanche sediment as moraine (Reznichenko et al., 2010; Reznichenko et al., 2011). Such aclimatic glacier response to a supraglacial rock avalanche deposit can confound apparent climatic signals extracted from moraine chronologies, which are widely used to infer regional climate change and are often correlated globally. Therefore, the origin of any particular dated moraine must be clarified before that date can be used for paleoclimatic interpretation. We present a new method that identifies the presence of rock avalanche sediment in moraines, based on the characteristics of the finest sediment fraction which contrast with those of non-rock-avalanche-derived glacial sediment. Under the dry, high-stress conditions during rock avalanche emplacement, fragmenting grains form agglomerates, which are absent in the wet, lower-stress processes of sub- and en-glacial environments. We show that these agglomerates are present in some moraines in the Southern Alps of New Zealand that have been attributed to climate fluctuation. This technique has the potential to resolve long-standing arguments about the role of rock avalanches in moraine formation and to enhance the use of moraines in palaeoclimatological studies. Reznichenko, N.V., Davies, T.R.H., Shulmeister, J. and McSaveney, M.J., 2010. Effects of debris on ice-surface melting rates: an experimental study. Journal of Glaciology, Vol. 56, No. 197, 384-394 Reznichenko, N.V., Davies, T.R.H. and Alexander, D.J., 2011. Effects of rock avalanches on glacier behaviour and moraine formation. Geomorphology, v. 132, is.3-4, p. 327-338

  18. Are there pre-Quaternary geological analogues for a future greenhouse warming?

    Science.gov (United States)

    Haywood, A.M.; Ridgwell, A.; Lunt, D.J.; Hill, D.J.; Pound, M.J.; Dowsett, H.J.; Dolan, A.M.; Francis, J.E.; Williams, M.

    2011-01-01

    Given the inherent uncertainties in predicting how climate and environments will respond to anthropogenic emissions of greenhouse gases, it would be beneficial to society if science could identify geological analogues to the human race's current grand climate experiment. This has been a focus of the geological and palaeoclimate communities over the last 30 years, with many scientific papers claiming that intervals in Earth history can be used as an analogue for future climate change. Using a coupled ocean-atmosphere modelling approach, we test this assertion for the most probable pre-Quaternary candidates of the last 100 million years: the Mid- and Late Cretaceous, the Palaeocene-Eocene Thermal Maximum (PETM), the Early Eocene, as well as warm intervals within the Miocene and Pliocene epochs. These intervals fail as true direct analogues since they either represent equilibrium climate states to a long-term CO2 forcing-whereas anthropogenic emissions of greenhouse gases provide a progressive (transient) forcing on climate-or the sensitivity of the climate system itself to CO2 was different. While no close geological analogue exists, past warm intervals in Earth history provide a unique opportunity to investigate processes that operated during warm (high CO2) climate states. Palaeoclimate and environmental reconstruction/modelling are facilitating the assessment and calculation of the response of global temperatures to increasing CO2 concentrations in the longer term (multiple centuries); this is now referred to as the Earth System Sensitivity, which is critical in identifying CO2 thresholds in the atmosphere that must not be crossed to avoid dangerous levels of climate change in the long term. Palaeoclimatology also provides a unique and independent way to evaluate the qualities of climate and Earth system models used to predict future climate. ?? 2011 The Royal Society.

  19. Late Pliocene and Quaternary Eurasian locust infestations in the Canary Archipelago

    Science.gov (United States)

    Meco, J.; Muhs, D.R.; Fontugne, M.; Ramos, A.J.; Lomoschitz, A.; Patterson, D.

    2011-01-01

    The Canary Archipelago has long been a sensitive location to record climate changes of the past. Interbedded with its basalt lavas are marine deposits from the principal Pleistocene interglacials, as well as aeolian sands with intercalated palaeosols. The palaeosols contain African dust and innumerable relict egg pods of a temperate-region locust (cf. Dociostaurus maroccanusThunberg 1815). New ecological and stratigraphical information reveals the geological history of locust plagues (or infestations) and their palaeoclimatic significance. Here, we show that the first arrival of the plagues to the Canary Islands from Africa took place near the end of the Pliocene, ca. 3Ma, and reappeared with immense strength during the middle Late Pleistocene preceding MIS (marine isotope stage) 11 (ca. 420ka), MIS 5.5 (ca. 125ka) and probably during other warm interglacials of the late Middle Pleistocene and the Late Pleistocene. During the Early Holocene, locust plagues may have coincided with a brief cool period in the current interglacial. Climatically, locust plagues on the Canaries are a link in the chain of full-glacial arid-cold climate (calcareous dunes), early interglacial arid-sub-humid climate (African dust inputs and locust plagues), peak interglacial warm-humid climate (marine deposits with Senegalese fauna), transitional arid-temperate climate (pedogenic calcretes), and again full-glacial arid-cold climate (calcareous dunes) oscillations. During the principal interglacials of the Pleistocene, the Canary Islands recorded the migrations of warm Senegalese marine faunas to the north, crossing latitudes in the Euro-African Atlantic. However, this northward marine faunal migration was preceded in the terrestrial realm by interglacial infestations of locusts. ??? Locust plagues, Canary Islands, Late Pliocene, Pleistocene, Holocene, palaeoclimatology. ?? 2010 The Authors, Lethaia ?? 2010 The Lethaia Foundation.

  20. Aeolian sands in continental red beds of the Middle Buntsandstein (Lower Triassic) at the western margin of the German Basin

    Science.gov (United States)

    Mader, Detlef

    1982-04-01

    anastomosing rivers, matching with the climax of regional diversification of depositional milieu. The aeolian sand sea in the Eifel covered an area of nearly 2500 km 2 at the time of its largest extension. The dune belt ended in the Northern Eifel, the alternating sequence passed into an entirely alluvial succession which graded northwards by continuously diminishing grain size into the central playa/lacustrine to marine sediment series in Northwest Germany. Palaeogeography, sedimentology and genesis of the Middle Buntsandstein at the western margin of the Mid-European Basin and of Rotliegendes in Northwest Germany appear to be partially similar as is revealed by certain characteristics of the palaeogeographical reconstructions. Concurrence of Middle Buntsandstein palaeogeographical models for both Eifel and the whole German Basin most clearly delineates the key position of the Eifel for interpretation of the Buntsandstein sedimentary environment and the palaeogeography in Middle Europe.

  1. Tilting of Lake Pielinen, eastern Finland – an example of extreme transgressions and regressions caused by differential post-glacial isostatic uplift

    Directory of Open Access Journals (Sweden)

    Heikki Seppä

    2012-08-01

    Full Text Available Tilting of large lakes due to differential isostatic uplift in the glaciated regions of the Northern Hemisphere is a well-documented process. With the help of accurate digital elevation models and spatial GIS analysis techniques, the resulting hydro­logical changes, including shifts in the outlets and changes in the size and configuration of lakes, can now be mapped and calculated more precisely than before. As a case study to highlight the magnitude of such changes in Fennoscandia, we investigated and reinterpreted the Holocene palaeogeography and palaeohydrology of Lake Pielinen in eastern Finland. This lake is currently 99 km long and located parallel to the direction of land uplift, being thus particularly sensitive to the impacts of tilting. Our results show that the lake was formed at the end of the regional deglaciation, following drainage of a local ice-dammed lake. In its initial stage until 10 200 cal yr BP, the outlet of the newly-formed lake was located in its northwestern end, but the tilting led to a major water level transgression in the basin, eventually causing formation of a new outlet over the southeastern threshold. The lake area was 143 km long and its area was 1998 km2 at the time of formation of the southeastern outlet at 10 200 cal yr BP. The lake level has been regressive throughout the basin during the last 10 200 years. This regression will continue for approximately another 10 000 years until all the glacial isostatic adjustment has occurred, after which Lake Pielinen will be only 89 km long and 565 km2 in area.

  2. Review of molar tooth structure research

    Directory of Open Access Journals (Sweden)

    Hong-Wei Kuang

    2014-10-01

    Full Text Available For more than a century, molar tooth structure (MTS has been studied. The study developed in three stages. During the first stage (before 1980, researchers described three basic morphologies of MTS, mainly from the Belt Supergroup in North America, and they provided several hypotheses for the origin of MTS. During the second stage (1980–1999, the frequent discoveries of MTS on all continents resulted in many detailed descriptions of their shape and in several hypotheses concerning the origin of MTS. Notably, hypotheses of MTS’s origin such as seismic activity and biological activity were developed. Since 2000, research has progressed into a new stage (the third stage. This is due to discoveries of MTS in the Meso–Neoproterozoic of China and elsewhere, and the ongoing debate on the seismic or biological origin is replaced by a hypothesis that involves gas expansion and chemically-controlled carbonate precipitation (both of them possibly affected by biological activities. This latter idea has gradually been commonly recognized as the mainstream theory. Despite continued disagreements, researchers now agree that microsparry calcite played a controlling role regarding the development and the global distribution of MTS in time and space during the Proterozoic, the morphological diversity, and the impact on the sedimentary environment. The present contribution analyses the three major hypotheses regarding the origin of MTS; it also discusses the shortcomings of the hypotheses regarding a seismic or biologic origin, and it details the modern hypothesis that links formation of cracks to the precipitation of sparry calcite. It is deduced that important questions dealing with the Precambrian can be answered, among other aspects regarding the depositional palaeogeography and stratigraphic correlations.

  3. The sedimentological characteristics of microbialites of the Cambrian in the vicinity of Beijing, China

    Directory of Open Access Journals (Sweden)

    Yin-Ye Wu

    2017-04-01

    Full Text Available With oil and gas exploration transferring to deeper and more ancient marine strata, more researches have been conducted about the Meso–Neoproterozoic and Cambrian microbial carbonate rocks by petroleum geologists. The Cambrian deposits experienced the first transgression of the Paleozoic, with shallow marine facies depositing in most areas, which are favorable for different kinds of biological reproduction. The Lower Cambrian in Beijing area is lithologically dominated by purple red shales interbedded with limestones, the Middle Cambrian is mainly composed of thick oolitic limestones, and the Upper Cambrian consists of thin limestones and flat-pebble conglomerates. Two beds of microbial carbonate rocks were discovered in the Cambrian outcrops in the vicinity of Beijing. One is from the Zhangxia Formation of Middle Cambrian, and the other is from the Gushan Formation of Upper Cambrian. The microbialites are characterized by combination of multiple stromatolites forming different bioherms. The bioherms are mostly in oval shape and with different sizes, which are 3–4 m long, and 1–3 m high. The surrounding strata beneath the bioherms are oolitic limestones. A central core of flat-pebble conglomerates occurred within each bioherm. Wavy or columnar stromatolites grow on the basis of flat-pebble conglomerates, with dentate erosional surfaces. The bioherm carbonate rocks are interpreted as products from a deep ramp sedimentary environment where potential oil and gas reservoirs can be found. The analysis of sedimentological characteristics of bioherm carbonate rocks and its lithofacies palaeogeography has significant implication for petroleum exploration. Research on geological record of microbialites is beneficial to investigating the Earth evolution, biodiversity, palaeoenvironment and palaeoclimate change, as well as biological extinction event during geological transitions. It also gives warning to human beings of modern biological crisis.

  4. Stable carbon and oxygen isotope stratigraphic evidence of Shuram Excursion and PC-C boundary in Bilara carbonate sequence of Rajasthan

    Science.gov (United States)

    Ansari, Arif; Pandey, Santosh; Sharma, Mukund; Agarwal, Shailesh; Kumar, Yogesh

    2017-04-01

    The Post-Cryogenian period was a time of sharp increase in ocean primary productivity and subsequent oxygenation to present atmospheric level (PAL), due to the massive influx of terrestrial weathering-derived nutrients in the sea. This change along with palaeogeography of continents during Late Ediacaran period instigated large scale deposition of carbonates with highly negative δ13C-carb. Like the continents those have established Shuram Excursion sites (i.e. Oman, Australia, China, North America), the location of Indian continent was also near atmospheric convergence zone (i.e. near the equator). Therefore a robust high-resolution carbon and oxygen stable isotope study was undertaken on Bilara carbonate sequences to test the possibility of Shuram Excursion and trace the Precambrian-Cambrian Boundary by comparing with well-dated established Shuram Excursion sites. The δ13C-carb and δ18O-carb in Bilara Group varies from -9.0 to 4.1 ‰ and from -10.7 to 8.3 ‰ respectively. Overall, most of the samples have δ18O-carb significantly above -10‰ below which carbonates are considered diagenetically altered. The δ13C-carb pattern is more similar to Yangtze Gorges platform where Ediacaran δ13C-carb variation profile has been divided into four negative (EN1, EN2, EN3, EN4) and three positive excursions (EP1, EP2, EP3). Similarities of δ13C-carb pattern demonstrate that Bilara is equivalent to Yangtze Gorges platform and, to some extent Shuram Formation. According to these comparisons, the Precambrian-Cambrian boundary lies near the top of Bilara Group.

  5. Deformations during uppermost Cretaceous-Early Eocene in NW Europe - The record of the Paris basin

    Science.gov (United States)

    Briais, Justine; Guillocheau, François; Robin, Cécile; Lasseur, Eric; Serrano, Olivier

    2014-05-01

    The uppermost Cretaceous to Early Paleocene is, in NW Europe, a period of major deformations with significant inversions during Turonian to Campanian times and during Early Paleocene. The mechanism of those inversions is still debated. Later on, a major uplift coeval with the Faroe-Shetland volcanic province occurred with a deformation regime still poorly understood. The objective of this study is to better constrain those deformations in the Paris Basin and to discuss their implications on the palaeogeography and the sedimentary systems. This study is based on well-dated wells and outcrops, correlated using the technique of "stacking pattern". In a second step, accommodation space measurements were performed from isopaches and facies maps. (1) The paroxysm of the deformation and the sharp decrease of the subsidence occurred between Late Campanian (with probably deposition of part of the Maastrichtian) and Early Danian, with the growth of a middle wavelength fold controlled by the Bray Fault. Danian carbonate platforms, mainly preserved south-west of Paris, are growing on unstable slightly consolidated chalk (numerous slumps). (2) A hiatus characterized part of the Danian, the Selandian and the base Thanetian. (3) Thanetian initiate a major change of sedimentary system (silicilastic) and of subsidence pattern, now located north of the Bray Fault, above the Early Liassic highly subsiding domains. (4) The Thanetian - Ypresian sediments do not record the eustatic signal, using the Zachos world sea temperature curve as a proxy (Haq's curve cannot be used anymore). This means that a significant deformation event overprints this signal, here the reactivation of the Seine Fault with inversion of some upper crust heterogeneities.

  6. Detrital zircon dating and tracing the provenance of dinosaur bone beds from the Late Cretaceous Wangshi Group in Zhucheng, Shandong, East China

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    Wei An

    2016-01-01

    Full Text Available The mass burial of dinosaur bone fossils in the Late Cretaceous Wangshi Group in Zhucheng, Shandong Province has been a research focus in recent years. However, the provenance of the dinosaur bone fossils and the accurate depositional age of the bone beds remain ambiguous. Through U–Pb dating of detrital zircons collected from six conglomerate samples from the dinosaur bone beds, we found that the youngest single grain age (YSG of sample 090414-24-D was 77.3 Ma, representing the maximum depositional age of the dinosaur fossil beds and sediments. This also indicates that the Hongtuya Formation was deposited during the Campanian. Dating results revealed an age peak of 120–110 Ma, which corresponds with the peak age of volcanic rocks of the Lower Cretaceous Qingshan Group. The volcanic rocks of the Qingshan Group are mainly exposed in Laiyang, to the north of Zhucheng, although a few also appear to the south and northwest. Through analysis of conglomerate composition and palaeocurrents in the sediments containing the bone beds, we found that the three different data sets of gravel compositions of the conglomerates were mainly composed of volcanic or pyroclastic rocks. Three different data sets of palaeocurrents suggested that the main sediment source of the Wangshi Group dinosaur bone beds was from the north−northwest of the Basin. Only one data set had a provenance south of the basin. This study revealed that the areas of Laiyang and the Yishu Fault Zone were the main provenance areas of both the dinosaur bone fossils and the sediments of the Wangshi Group in Zhucheng. The southern margin of the Zhucheng Basin may be a secondary source area. This research provides an important basis for judging the deposition time and the sediment source of fossil layers in the Wangshi Group, as well as reconstructing the palaeogeography of the Wangshi Group in the Jiaolai Basin.

  7. Abrupt Climate Change Around 850 Cal Bc From Central Africa To Northern Europe and The Role of Solar Uv

    Science.gov (United States)

    van Geel, B.; Renssen, H.; van der Plicht, J.

    Changing solar activity is a possible factor behind rapid climate shifts. Matching of high resolution sequences of uncalibrated 14C dates of organic deposits to the dendro- calibration curve can provide a precise core chronology. This method (14C wiggle matching) reveals relationships between atmospheric 14C variations and short-term climatic fluctuations caused by solar variations. Shifts to cool and wet climate types in the temperate zones correspond to phases of increasing and high values of delta 14C, pointing to a link between changing solar activity and climate change. In the temperate zones the transition from the Subboreal to the Subatlantic (ca 850 calendar years BC) represents a sudden and strong shift from a relatively dry and warm climate to a humid and cool episode. The climate shift is reflected in the plant macrofossil composition of NW European raised bogs, but there is also strong archaeological and dendroclimatological evidence. The climate shift occurs at the start of a sharp rise of the atmospheric 14C content, caused by a sudden decline of solar activity. Reduced solar wind permitted more cosmic rays to penetrate into the atmosphere, resulting in a higher production of the cosmogenic isotope 14C. In Cameroon and other sites in the Central African rain forest belt there was a drastic change in the vegetation cover as a consequence dryness after ca 850 cal BC. Shortly afterwards farmers migrated into the area, availing themselves of what was from the human standpoint a regional climatic improvement. A possible palaeoclimatological explanation for the dry-wet transition in the temperate zones, and the contemporaneous wet-dry transition in the tropics is the following: A reduction in solar activity (less solar UV) resulted in a decrease of stratospheric ozone, less absorption of warmth, an equatorward shift and intensification of the mid-latitude storm tracks, a constriction of the latitudinal extent of the Hadley Cell circulation and thus a weaker

  8. Possibilities of 3-D modelling and quantitative morphometric analysis of decimeter-sized Echinoids using photogrammetric approach

    Science.gov (United States)

    Polonkai, Bálint; Görög, Ágnes; Raveloson, Andrea; Bodor, Emese; Székely, Balázs

    2017-04-01

    Echinoids (sea urchins) are useful fossils in palaeoenvironmental reconstruction for e.g. palaeobiogeography, palaeoclimatology or sedimentatological researches. In the Hungarian Badenian stage (Langhian, Middle Miocene) the species Parascutella gibbercula (DE SERRES 1829) is a common taxon and indicate shallow marine environment. The specimens of this extinct species show high morphological variability within relatively small geographical areas, even within one given strata. These differences can have a relevant palaeontological and/or palaeoenvironmental information. It is necessary for the interpretation of the value of the morphological parameters to quantify them in properties. Among the possible quantification methods 3D photogrammetric reconstruction is found to be suitable; recent years have seen its increasing palaeontological application both on invertebrates and vertebrates. In order to generate proper 3D models of the specimens with the required details a great number of digital images have to be shot. In case of proper data acquisition and precise model generation it is possible to outperform the traditional 2D morphometric studies of the echinoids that are often inaccurate when the spatial characters as well as ambulacral system and the conical shaped apex (top of the test) are measured. An average P . gibbercula specimen is about 10 cm diameter. Therefore, desktop image acquisition is possible if appropriate lighting conditions are provided. For better results we have designed an elaborate target background pattern that enhances the chances to find homologous points in the imagery. Agisoft Photoscan software has been used for the model generation. The generated models typically show high-resolution details and reproduce original colours. However, various problems may occur: improper focusing and/or poor lighting conditions may cause hardly patchable aboral and oral side, and/or shallow surface undulations cannot be modelled appropriately. Another

  9. On the origin and evolution of Antarctic Peracarida (Crustacea, Malacostraca

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    Angelika Brandt

    1999-12-01

    Full Text Available The early separation of Gondwana and the subsequent isolation of Antarctica caused a long evolutionary history of its fauna. Both, long environmental stability over millions of years and habitat heterogeneity, due to an abundance of sessile suspension feeders on the continental shelf, favoured evolutionary processes of preadapted taxa, like for example the Peracarida. This taxon performs brood protection and this might be one of the most important reasons why it is very successful (i.e. abundant and diverse in most terrestrial and aquatic environments, with some species even occupying deserts. The extinction of many decapod crustaceans in the Cenozoic might have allowed the Peracarida to find and use free ecological niches. Therefore the palaeogeographic, palaeoclimatologic, and palaeo-hydrographic changes since the Palaeocene (at least since about 60 Ma ago and the evolutionary success of some peracarid taxa (e.g. Amphipoda, Isopoda led to the evolution of many endemic species in the Antarctic. Based on a phylogenetic analysis of the Antarctic Tanaidacea, Sieg (1988 demonstrated that the tanaid fauna of the Antarctic is mainly represented by phylogenetically younger taxa, and data from other crustacean taxa led Sieg (1988 to conclude that the recent Antarctic crustacean fauna must be comparatively young. His arguments are scrutinized on the basis of more recent data on the phylogeny and biodiversity of crustacean taxa, namely the Ostracoda, Decapoda, Mysidacea, Cumacea, Amphipoda, and Isopoda. This analysis demonstrates that the origin of the Antarctic fauna probably has different roots: an adaptive radiation of descendants from old Gondwanian ancestors was hypothesized for the isopod families Serolidae and Arcturidae, an evolution and radiation of phylogenetically old taxa in Antarctica could also be shown for the Ostracoda and the amphipod family Iphimediidae. A recolonization via the Scotia Arc appears possible for some species, though it is

  10. Lake Van carbonates: Implications for lacustrine stable isotope analysis

    Science.gov (United States)

    McCormack, Jeremy; Immenhauser, Adrian; Kwiecien, Ola

    2017-04-01

    Carbonate stable isotope (δ18O and δ13C) analysis is a commonly applied and powerful proxy in lacustrine palaeoclimatology. In the absence of large quantities of detrital carbonates, the bulk carbonate is assumed to mainly represent inorganic carbonates precipitated in the epilimnion. In well-preserved, geologically young sediments (e.g. varves), post-depositional processes affecting the mineralogy or geochemistry of sedimentary carbonates are difficult to recognise. In case of terminal and alkaline Lake Van, the interpretation of the δ18O and δ13C signals of bulk carbonates is, in comparison to other proxies, far from straightforward when relying on traditional interpretative approaches. Consequently, using a multi-component approach we studied, individually and in detail, various components comprising Lake Van's bulk carbonates. Samples investigated here cover the last glacial/interglacial period. Inorganic ( 63 μm) carbonates were isolated by wet-sieving and analysed by means of XRD, SEM and isotope mass spectrometry. High-resolution mineralogical analysis revealed variable amounts of aragonite and calcite as well as early diagenetic non-stoichiometric (calcian) dolomite. The early diagenetic dolomite appears to be replacing the inorganic aragonite/calcite and occurs within finely-laminated, organic-rich sediments. Isotopically the dolomite differs significantly from the primary carbonates with typically heavier δ18O and lighter δ13C values. Thus, in the case of bulk sediment isotope analysis the presence of higher amounts of diagenetic dolomite is distorting the isotopic pattern. Ostracod valves represent biogenic carbonates. However, apart from well-preserved, translucent carapaces we have found coated ones, reoccurring throughout the profile within specific facies types. The coating, comprising mainly of aragonite has a significantly heavier δ18O and δ13C signature compared to coeval inorganic carbonates, precipitated presumably in the surface water

  11. Mid- to late Holocene Indian Ocean Monsoon variability recorded in four speleothems from Socotra Island, Yemen

    Science.gov (United States)

    Van Rampelbergh, Maïté; Fleitmann, Dominik; Verheyden, Sophie; Cheng, Hai; Edwards, Lawrence; De Geest, Peter; De Vleeschouwer, David; Burns, Stephen J.; Matter, Albert; Claeys, Philippe; Keppens, Eddy

    2013-04-01

    Four stalagmites covering the last 7.0 ka were sampled on Socotra, an island in the northern Indian Ocean to investigate the evolution of the northeast Indian Ocean Monsoon (IOM) since the mid Holocene. On Socotra, rain is delivered at the start of the southwest IOM in May-June and at the start of the northeast IOM from September to December. The Haggeher Mountains act as a barrier forcing precipitation brought by the northeast winds to fall preferentially on the eastern side of the island, where the studied caves are located. δ18O and δ13C and Mg/Ca and Sr/Ca signals in the stalagmites reflect precipitation amounts brought by the northeast winds. For stalagmite STM6, this amount effect is amplified by kinetic effects during calcite deposition. Combined interpretation of the stalagmites' signals suggest a weakening of the northeast precipitation between 6.0 and 3.8 ka. After 3.8 ka precipitation intensities remain constant with two superimposed drier periods, between 0 and 0.6 ka and from 2.2 to 3.8 ka. No link can be established with Greenland ice cores and with the summer IOM variability. In contrast to the stable northeast rainy season suggested by the records in this study, speleothem records from western Socotra indicate a wettening of the southwest rainy season on Socotra after 4.4 ka. The local wettening of western Socotra could relate to a more southerly path (more over the Indian Ocean) taken by the southwest winds. Stalagmite STM5, sampled at the fringe between both rain areas displays intermediate δ18O values. After 6.2 ka, similar precipitation changes are seen between eastern Socotra and northern Oman indicating that both regions are affected similarly by the monsoon. Different palaeoclimatologic records from the Arabian Peninsula currently located outside the ITCZ migration pathway display an abrupt drying around 6 ka due to their disconnection from the southwest rain influence. Records that are nowadays still receiving rain by the southwest winds

  12. Developing a visual moraine classification scheme to support investigations into the Holocene glacier chronology of the Southern Alps, New Zealand

    Science.gov (United States)

    Kaufung, Eva; Winkler, Stefan

    2014-05-01

    The Southern Alps of New Zealand have provided one of only a few suitable study sites for investigating Holocene glacier chronologies in the mid-latitudinal Southern Hemisphere. Although a considerable number of studies have been conducted during the past few decades, these generally focus on a very limited number of glacier forelands. Additionally, those glaciers studied have often been selected because of their accessibility rather than their representativeness for the whole region. A common drawback of many regional studies is the lack of attention to glacial geomorphology and the mode of moraine formation with the dating of such landforms in chronological context. With the Southern Alps characterized by very dynamic geomorphological process-systems and a high seismic activity, this seems unfortunate as it causes a relatively high potential "geomorphological uncertainty" with any published glacier chronology and its subsequent palaeoclimatological interpretation. Future investigations into the Holocene glacier chronology in the Southern Alps need to address those existing shortcomings and, consequently, should achieve a representative spatial distribution of study sites in order to overcome the current strong data bias towards few, albeit relatively well-studied glacier forelands. The specific regional geomorphological environment of the Southern Alps requires, furthermore, a thorough assessment of any moraine selected for the subsequent dating in consideration of its "reliability" if it is considered as evidence of specific former glacier variations. With more than 3000 potential glacier forelands in the entire mountain range, careful selection of future targets for successful chronological field work is essential. We present the preliminary results of an ongoing, time-efficient study to apply different remote sensing sources (aerial photography, Google Earth, satellite images) to evaluate the potential of certain glacier forelands for detailed ground

  13. Bottom current processes along the Iberian continental margin; Procesos sedimentarios por corrientes de fondo a lo largo del margen continental iberico

    Energy Technology Data Exchange (ETDEWEB)

    Llave, E.; Hernandez-Molina, F. J.; Ercilla, G.; Roque, C.; Van Rooij, D.; Garcia, M.; Juan, C.; Mena, A.; Brackenridge, R.; Jane, G.; Stow, D.; Gomez-Ballesteros, M.

    2015-07-01

    -slope processes and their sedimentary impact around the Iberian margin. Despite the numerous examples of bottom current processes recorded, there remains a number of challenges to understanding CDSs around the Iberian margin including: 1) evidencing their important scientific implications (stratigraphy, sedimentology, palaeoceanography and palaeoclimatology); assess- ing their geological hazard and their economic potential (for mineral and energy resources); and 3) using them to create conceptual models for CDS formation. There is a lack of complete knowledge about the different oceanographic processes that may drive bottom currents, and there is also the need to document the great variety of contourite features (processes and products) and facies models, along with their evolution over time and space. Therefore advances, both in new technologies and integrated studies (Geology, Physical Oceanography and Benthic/planktonic Biology), are anticipated. (Author)

  14. Effect of different fertilizer resources on yield and yield components of grain maize (Zea mays L. affected by tillage managements

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    Ahmad Ghasemi

    2016-03-01

    , the root growth limited during the first year of no tillage. Organic Food Systems (green manure and animal manure provide the mineral food for plants. However, the low rate of mineralization in the early stages of root development can limit the nutrient availability. Nevertheless, these limits are removed over time. Integration of green manure, animal manure, and chemical fertilizer with conventional tillage not only strengthens the initial growth but it also accelerates the mineralization. In general, it can be concluded that application of green, animal, and chemical manures and conventional tillage for corn production can both reduce chemical fertilizer and environmental pollution and play a positive role in increasing the yield of maize. Keywords: Barley, Ear length, 1000- Grain weight, Harvest index, No tillage References Nuralvandy, T., Ardekani, M.R., Kashani, H., Vazan, S., and Sadeghi Shoa, M. 2011. Effect of chemical and organic fertilizers on morphological characteristics and yield of sweet corn. Agronomy Journal 7(3: 1-12. (In Persian with English Summary Tajbakhsh, M., Hassanzadeh Ghurttape, H., and Darvishzadeh, B. 2005. Green manures in sustainable agriculture. Printing 1, Publishing Jihad Uromia University 215 pp. (In Persian

  15. Model study of the Mediterranean-Atlantic water exchange prior to the Messinian Salinity Crisis: An alternative to the "siphon theory"

    Science.gov (United States)

    de la Vara, Alba; Topper, Robin; Meijer, Paul; Wortel, Rinus

    2014-05-01

    During the Late Miocene the Mediterranean Sea and the Atlantic Ocean were connected by means of two marine passages - the Betic and Rifian corridors. The severe restriction of these corridors due to tectonic processes, in combination with glacio-eustatic sea-level fluctuations, resulted in the so-called Messinian Salinity Crisis. During this event thick sequences of evaporites were deposited in the Mediterranean Sea evidencing dramatic changes in the palaeoenvironmental conditions. Although the present-day water exchange through the Strait of Gibraltar has been extensively studied, little is certain about the gateway dynamics leading up to the Messinian Salinity Crisis. Knowledge of the behavior of these corridors would be important to be able to link observations (e.g., sedimentary record, faunal or isotope studies) to the corresponding gateway geometries. The objective of this work is to gain physics-based understanding into the role of the interplay of the depth of the two gateways on the Atlantic-Mediterranean water exchange before the Salinity Crisis. To this end we use the regional ocean circulation model SbPOM, which is a parallel version of the Princeton Ocean Model, and Upper Tortonian palaeogeography. The experiments cover systematically various shoaling sequences ranging from relatively deep to closed corridors. Our results do not support the classic "siphon theory" proposed by Benson et al. (1991) for a double gateway scenario prior to the Messinian Salinity Crisis. These authors suggest unidirectional flow from the Atlantic into the Mediterranean via the Rifian corridor and Mediterranean outflow through the Betic one. In contrast, we find that different flow configurations are possible depending on the depth of one corridor relative to the other. More specifically, when one corridor is shallower than approximately half the depth of the other one, there is one-way flow through the shallow corridor and two-way flow in the deep one. In contrast, when one

  16. Climatic and palaeoceanographic changes during the Pliensbachian (Early Jurassic) inferred from clay mineralogy and stable isotope (C-O) geochemistry (NW Europe)

    Science.gov (United States)

    Bougeault, Cédric; Pellenard, Pierre; Deconinck, Jean-François; Hesselbo, Stephen P.; Dommergues, Jean-Louis; Bruneau, Ludovic; Cocquerez, Théophile; Laffont, Rémi; Huret, Emilia; Thibault, Nicolas

    2017-02-01

    The Early Jurassic was broadly a greenhouse climate period that was punctuated by short warm and cold climatic events, positive and negative excursions of carbon isotopes, and episodes of enhanced organic matter burial. Clay minerals from Pliensbachian sediments recovered from two boreholes in the Paris Basin, are used here as proxies of detrital supplies, runoff conditions, and palaeoceanographic changes. The combined use of these minerals with stable isotope data (C-O) from bulk carbonates and organic matter allows palaeoclimatic reconstructions to be refined for the Pliensbachian. Kaolinite/illite ratio is discussed as a reliable proxy of the hydrological cycle and runoff from landmasses. Three periods of enhanced runoff are recognised within the Pliensbachian. The first one at the Sinemurian-Pliensbachian transition shows a significant increase of kaolinite concomitant with the negative carbon isotope excursion at the so-called Sinemurian Pliensbachian Boundary Event (SPBE). The Early/Late Pliensbachian transition was also characterised by more humid conditions. This warm interval is associated with a major change in oceanic circulation during the Davoei Zone, likely triggered by sea-level rise; the newly created palaeogeography, notably the flooding of the London-Brabant Massif, allowed boreal detrital supplies, including kaolinite and chlorite, to be exported to the Paris Basin. The last event of enhanced runoff occurred during the late Pliensbachian (Subnodosus Subzone of the Margaritatus Zone), which occurred also during a warm period, favouring organic matter production and preservation. Our study highlights the major role of the London Brabant Massif in influencing oceanic circulation of the NW European area, as a topographic barrier (emerged lands) during periods of lowstand sea-level and its flooding during period of high sea-level. This massif was the unique source of smectite in the Paris Basin. Two episodes of smectite-rich sedimentation ('smectite

  17. Widespread horizontal genomic exchange does not erode species barriers among sympatric ducks

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    Kraus Robert HS

    2012-04-01

    Full Text Available Abstract Background The study of speciation and maintenance of species barriers is at the core of evolutionary biology. During speciation the genome of one population becomes separated from other populations of the same species, which may lead to genomic incompatibility with time. This separation is complete when no fertile offspring is produced from inter-population matings, which is the basis of the biological species concept. Birds, in particular ducks, are recognised as a challenging and illustrative group of higher vertebrates for speciation studies. There are many sympatric and ecologically similar duck species, among which fertile hybrids occur relatively frequently in nature, yet these species remain distinct. Results We show that the degree of shared single nucleotide polymorphisms (SNPs between five species of dabbling ducks (genus Anas is an order of magnitude higher than that previously reported between any pair of eukaryotic species with comparable evolutionary distances. We demonstrate that hybridisation has led to sustained exchange of genetic material between duck species on an evolutionary time scale without disintegrating species boundaries. Even though behavioural, genetic and ecological factors uphold species boundaries in ducks, we detect opposing forces allowing for viable interspecific hybrids, with long-term evolutionary implications. Based on the superspecies concept we here introduce the novel term "supra-population" to explain the persistence of SNPs identical by descent within the studied ducks despite their history as distinct species dating back millions of years. Conclusions By reviewing evidence from speciation theory, palaeogeography and palaeontology we propose a fundamentally new model of speciation to accommodate our genetic findings in dabbling ducks. This model, we argue, may also shed light on longstanding unresolved general speciation and hybridisation patterns in higher organisms, e.g. in other bird

  18. First results of the palaeogeographical research in Limyra and its environs (SW-Turkey)

    Science.gov (United States)

    Stock, Friederieke; Uncu, Levent; Seyer, Martin; Brückner, Helmut

    2017-04-01

    Geoarchaeological research in and around ancient cities of Asia Minor is an important tool for reconstructing the palaeogeography of their environs. An intensive geoarchaeological research project has started 2015 in the framework of a cooperation between the Austrian Archaeological Institute (ÖAI) and the University of Cologne (Brückner et al., 2016). 21 sediment cores were carried out in the ancient city of Limyra and its environs since 2015 and analysed with a multi-proxy approach (geochemical, sedimentological and microfaunal methods). The main goals of the project are to reconstruct (i) the environment, especially during the Classical to Late Roman periods; (ii) the geohydrological situation; (iii) the thickness of the settlement layers; (iv) the maximum extension of the former lake; to reveal (vi) the earthquake chronology and (vii) the spatio-temporal shifts in the coastline. First results show that the middle and eastern part of the city had been built on top of former lake sediments. Peat layers (so-called "floating peats") are intercalated and represent the starting siltation process. The reactivated lake phases, expressed in the rapid transitions from peat to lake strata, may be explained by earthquakes with co-seismic subsidence. Then follow fluvial sands with a fining-upward sequence (gravel at the base, overlain sands and alluvia). The strata provide information about shifting river channels. Anthropogenic layers form the top part of the core; they partly consolidated a swampy environment (core-filling limestone layers). In drill cores located between the eastern and the western city, pebbles and edged stones with artifacts follow on top of lake sediments and sands (littoral). The stones seem to have been intentionally deposited; people may have settled at the lake shore. The peat layer on top may represent the changing hydrology and co-seismic subsidence. The drill cores outside the city area confirm the sediment sequence: on top of limnic follow

  19. The impact of precession and obliquity on the Late-Devonian greenhouse climate

    Science.gov (United States)

    De Vleeschouwer, D.; Crucifix, M.; Bounceur, N.; Claeys, P. F.

    2012-12-01

    To date, only few general circulation model (GCM) have been used to simulate the extremely warm greenhouse climate of the Late-Devonian (~370 Ma). As a consequence, the current knowledge on Devonian climate dynamics comes almost exclusively from geological proxy data. Given the fragmentary nature of these data sources, the understanding of the Devonian climate is rather limited. Nonetheless, the Late-Devonian is a key-period in the evolution of life on Earth: the continents were no longer bare but were invaded by land plants, the first forests appeared, soils were formed, fish evolved to amphibians and 70-80% of all animal species were wiped out during the Late Devonian extinction (~376 Ma). In order to better understand the functioning of the climate system during this highly important period in Earth's history, we applied the HadSM3 climate model to the Devonian period under different astronomical configurations. This approach provides insight into the response of Late-Devonian climate to astronomical forcing due to precession and obliquity. Moreover, the assessment of the sensitivity of the Late-Devonian climate to astronomical forcing, presented here, will allow cyclostratigraphers to make better and more detailed interpretations of recurring patterns often observed in Late-Devonian sections. We simulated Late-Devonian climates by prescribing palaeogeography, vegetation distribution and pCO2 concentration (2180 ppm). Different experiments were carried out under 31 different astronomical configurations: three levels for obliquity (ɛ = 22°; 23.5° and 24.5°) and eccentricity (e = 0; 0.03 and 0.07) were chosen. For precession, 8 levels were considered (longitude of the perihelion= 0°; 45°; 90°; 135°; 180°; 235°; 270°). First results suggest that the intensity of precipitation on the tropical Euramerican continent (also known as Laurussia) is highly dependent on changes in precession: During precession maxima (= maximal insolation in SH during winter

  20. Unconfined alluvial flow processes: Recognition and interpretation of their deposits, and the significance for palaeogeographic reconstruction

    Science.gov (United States)

    North, Colin P.; Davidson, Stephanie K.

    2012-02-01

    grain size or bed thickness. Similar lithofacies may develop in a wide range of geomorphic and climatic settings because the deposits solely reflect the local flow conditions and sediment availability. We recommend that the terms 'sandflat' and 'sheetflood' should not be used in sedimentological accounts because there is no longer a safe informal usage for either; contradictory application of these terms, and lack of robust definitions, is leading to significant misunderstanding of palaeogeography and process. Our analysis should improve reconstruction of past terrestrial environments because it reveals more clearly the true variety of possibilities for the occurrence of unconfined flow and the resultant deposits. Enhanced understanding of the inherent uncertainties, and realisation of the wider range of plausible alternative explanations, should help resolve apparent contradictions with independent indicators of climate or geographic position.

  1. The Jurassic of North-East Greenland: A new Middle–Upper Jurassic succession on Hold with Hope, North-East Greenland

    Directory of Open Access Journals (Sweden)

    Vosgerau, Henrik

    2004-11-01

    Full Text Available A succession of marine, Jurassic sediments was recently discovered on Hold with Hope, North-East Greenland. The discovery shows that the area was covered by the sea during Middle–Late Jurassic transgressive events and thus adds to the understanding of the palaeogeography of the area. The Jurassic succession on northern Hold with Hope is exposed in the hangingwalls of small fault blocks formed by rifting in Late Jurassic – Early Cretaceous times. It unconformably overlies Lower Triassic siltstones and sandstones and is overlain by Lower Cretaceous coarsegrained sandstones with an angular unconformity. The succession is up to 360 m thick andincludes sandstones of the Lower–Upper Callovian Pelion and Middle–Upper Oxfordian Payer Dal Formations (Vardekløft Group and heteroliths and mudstones of the Upper Oxfordian – Lower Kimmeridgian Bernbjerg Formation (Hall Bredning Group. The Pelion Formation includes the new Spath Plateau Member (defined herein.The palaeogeographic setting was a narrow rift-controlled embayment along the western margin of the rifted Jurassic seaway between Greenland and Norway. It was open to marine circulation to the south as indicated by the distribution and lateral facies variations and a dominant south-westwards marine palaeocurrent direction. The Pelion and Payer Dal Formations represent upper shoreface and tidally influenced delta deposits formed by the migration of dunes in distributary channels and mouthbars over the delta front. The boundary between the two formations is unconformable and represents a Late Callovian – Middle Oxfordian hiatus. It is interpreted to have formed by subaerial erosion related to a sea-level fall combined with minor tilting of fault blocks and erosion of uplifted block crests.In Late Jurassic time, the sand-rich depositional systems of the Pelion and Payer Dal Formations drowned and offshore transition – lower shoreface heteroliths and offshore mudstones of the Bernbjerg

  2. Mio-Pliocene evolution of the Gharb Sub-Basin, offshore Morocco

    Science.gov (United States)

    Dmitrieva, Evelina; Gerard, Jean; Abdallah, Hussein

    2014-05-01

    -Sub basin geometry, Mio-Pliocene palaeogeography and tectono-sedimentary evolution. This will compliment related studies focusing on the analogous Mio-Pliocene succession onshore.

  3. Western Tethys continental-marine responses to the Carnian Humid Episode: Palaeoclimatic and palaeogeographic implications

    Science.gov (United States)

    López-Gómez, J.; Escudero-Mozo, M. J.; Martín-Chivelet, J.; Arche, A.; Lago, M.; Galé, C.

    2017-01-01

    junction in sector 4, and configuring a palaeogeography of elevated and subsiding blocks, which controlled both continental and marine sedimentation in the study area.

  4. Foraminiferal assemblages and geochemistry for interpreting the incidence of Early Toarcian environmental changes in North Gondwana palaeomargin (Traras Mountains, Algeria)

    Science.gov (United States)

    Reolid, Matías; Marok, Abbas; Sèbane, Abbes

    2014-07-01

    assemblages in the Tlemcen Domain is compared with the high incidence and delayed recovery in the Saharan Basin, where the palaeogeography determined restricted water circulation between the Saharan Craton and the Oran Massif.

  5. Estudio paleobotánico del afloramiento vallesiense (Neógeno del barranco de Salanca (la Cerdaña, Lérida, España. Aspectos paleoecológicos

    Directory of Open Access Journals (Sweden)

    Barrón, Eduardo

    1999-06-01

    Full Text Available An integral palaeobotanical study (macro- and microflora has been done of the Salanca ravine outcrop. This place is located in the región of la Cerdaña (Lérida province, Spain, which constitutes an Upper Miocene lacustrine basin from Eastern Pyrenees. The sediments of the Salanca ravine outcrop consist of diatomites and grey mudstones. They have been interpreted as being deposited in distal lacustrine zones. In a palynological study, 79 taxa have been identified. They belong to the divisions Pteridophyta, Pinophyta and Magnoliophyta. The recorded assemblages allow us to reconstruct the vegetation of la Cerdaña during the Vallesian, though the problem of overrepresented taxa exists. The macrofloristic study has revealed the presence of 36 taxa through foliar remanís and winged seeds. The recorded assemblage presents plant remains of the divisions Pinophyta and Magnoliophyta. The best represented remains are leaves of dicotyledonous angiosperms because of their wind transport. The high percentage of angiosperm foliar remains in the sediments of the Salanca ravine outcrop revealed calm water conditions in the neogene lake. The palaeoclimatology deduced from the palynological study and the physiognomic study of macroflora indicates that températe conditions existed in which mixed mesophitíc forest developed where the families Pinaceae, Betulaceae and Fagaceae dominated.Se realiza un estudio paleobotánico (macro- y microflora del afloramiento del barranco de Salanca (comarca de la Cerdaña, Pirineos orientales, Lérida, España. En esta zona durante el Mioceno Superior se desarrolló una cuenca lacustre. Los materiales del barranco de Salanca son fundamentalmente diatomitas y "mudstones" de color gris, que se depositaron en zonas lacustres distales. Tras el estudio palinológico, se han identificado 79 táxones pertenecientes a las divisiones Pteridophyta, Pinophyta y Magnoliophyta. Las asociaciones registradas nos permiten reconstruir la

  6. Stable isotopic analysis of fossil chironomids as an approach to environmental reconstruction: state of development and future challenges

    Directory of Open Access Journals (Sweden)

    Oliver Heiri

    2012-10-01

    chironomid remains have the potential to provide reconstructions of past climatic change (H, O and insights into past food web structure, methane production and pollution of lake ecosystems (N, C. Future efforts will be necessary to develop these approaches including more detailed analyses of the effects of sample pretreatment on stable isotope measurements on chitinous fossils, more extensive laboratory studies constraining the effects of external factors (e.g., isotopic composition of food and ambient water, temperature on stable isotopes in chironomid larvae, and surveys exploring seasonal changes in the isotopic composition of chironomid larvae and assessing how this seasonality influences fossil assemblages. Finally, multi-site field studies relating chironomid δD, δ15N, δ13C and δ18O to parameters such as δ18O of precipitation, air and water temperatures, and nutrient and greenhouse gas concentrations in lakes will be necessary to assess the extent to which these stable isotopic approaches can provide quantitative reconstructions of parameters of interest for palaeoclimatological and palaeoenvironmental research.doi: 10.5324/fn.v31i0.1436.Published online: 17 October 2012.

  7. Geographical and climatic limits of needle types of one- and two-needled pinyon pines

    Science.gov (United States)

    Cole, K.L.; Fisher, J.; Arundel, S.T.; Cannella, J.; Swift, S.

    2008-01-01

    Aim: The geographical extent and climatic tolerances of one- and two-needled pinyon pines (Pinus subsect. Cembroides) are the focus of questions in taxonomy, palaeoclimatology and modelling of future distributions. The identification of these pines, traditionally classified by one- versus two-needled fascicles, is complicated by populations with both one- and two-needled fascicles on the same tree, and the description of two more recently described one-needled varieties: the fallax-type and californiarum-type. Because previous studies have suggested correlations between needle anatomy and climate, including anatomical plasticity reflecting annual precipitation, we approached this study at the level of the anatomy of individual pine needles rather than species. Location: Western North America. Methods: We synthesized available and new data from field and herbarium collections of needles to compile maps of their current distributions across western North America. Annual frequencies of needle types were compared with local precipitation histories for some stands. Historical North American climates were modelled on a c. 1-km grid using monthly temperature and precipitation values. A geospatial model (ClimLim), which analyses the effect of climate-modulated physiological and ecosystem processes, was used to rank the importance of seasonal climate variables in limiting the distributions of anatomical needle types. Results: The pinyon needles were classified into four distinct types based upon the number of needles per fascicle, needle thickness and the number of stomatal rows and resin canals. The individual needles fit well into four categories of needle types, whereas some trees exhibit a mixture of two needle types. Trees from central Arizona containing a mixture of Pinus edulis and fallax-type needles increased their percentage of fallax-type needles following dry years. All four needle types occupy broader geographical regions with distinctive precipitation regimes

  8. Pollen-based reconstruction of Holocene climate variability in the Eifel region evaluated with stable isotopes

    Science.gov (United States)

    Kühl, Norbert; Moschen, Robert; Wagner, Stefanie

    2010-05-01

    sediments might strongly react to anthropogenic deforestation, as carbon isotope time series from the adjacent Lake Holzmaar suggest. Reconstructions based on pollen with the pdf-method are robust to the human impact during the last 4000 years, but do not reproduce the fine scale climate variability that can be derived from the stable isotope series (Kühl et al., in press). In contrast, reconstructions on the basis of pollen data show relatively pronounced climate variability (here: January temperature) during the Mid-Holocene, which is known from many other European records. The oxygen isotope time series as available now indicate that at least some of the observed variability indeed reflects climate variability. However, stable carbon isotopes show little concordance. At this stage our results point in the direction that 1) the isotopic composition might reflect a shift in influencing factors during the Holocene, 2) climate trends can robustly be reconstructed with the pdf method and 3) fine scale climate variability can potentially be reconstructed using the pdf-method, given that climate sensitive taxa at their distribution limit are present. The latter two conclusions are of particular importance for the reconstruction of climatic trends and variability of interglacials older than the Holocene, when sites are rare and pollen is often the only suitable proxy in terrestrial records. Kühl, N., Moschen, R., Wagner, S., Brewer, S., Peyron, O., in press. A multiproxy record of Late Holocene natural and anthropogenic environmental change from the Sphagnum peat bog Dürres Maar, Germany: implications for quantitative climate reconstructions based on pollen. J. Quat. Sci., DOI: 10.1002/jqs.1342. Available online. Moschen, R., Kühl, N., Rehberger, I., Lücke, A., 2009. Stable carbon and oxygen isotopes in sub-fossil Sphagnum: Assessment of their applicability for palaeoclimatology. Chemical Geology 259, 262-272.

  9. Testing the sensitivity of stable carbon isotopes of sub-fossil Sphagnum cellulose to past climate variability: a two millennia high resolution stable carbon isotope time series from the peat deposit "Dürres Maar", Germany

    Science.gov (United States)

    Moschen, Robert; Kühl, Norbert; Peters, Sabrina; Vos, Heinz; Lücke, Andreas

    2010-05-01

    CSphagnum. The close coupling of several environmental factors to air temperature, however, presumably also results in an indirect dependency of δ13CSphagnum on air temperature, since strong correlation between δ13CSphagnum of modern Sphagnum plants and local air temperature during the growing season has been observed for altitudinal transects (Skrzypek et al. 2007). We applied potential relationships between our δ13CSphagnum and climatological parameters as deducible from existing calibration data sets. Results are compared with quantitative climate reconstructions based on well established palynological methods applied to the same core from 'Dürres Maar'. Additionally, comparisons of the δ13CSphagnum record with time series of meteorological observations are presented to review the potential relationships between δ13CSphagnum and climatological parameters. References: Loader, N.L., McCarroll, D., van der Knaap, W.O., Robertson, I. and Gagen, M., (2007): Characterizing carbon isotopic variability in Sphagnum. The Holocene 17: 403-410. Skrzypek, G., Kalużny, A., Wojtuń, B. and Jędrysek, M.-O., (2007): The carbon stable isotopic composition of mosses: A record of temperature variation. Organic Geochemistry 38: 1770-1781. Moschen, R. et al. (2009): Stable carbon and oxygen isotopes in sub-fossil Sphagnum: Assessment of their applicability for palaeoclimatology. Chemical Geology 259: 262-272.

  10. Should precise numerical dating overrule glacial geomorphology?

    Science.gov (United States)

    Winkler, Stefan

    2016-04-01

    Numerical age dating techniques, namely different types of terrestrial cosmogenic nuclide dating (TCND), have achieved an impressive progress in both laboratory precision and regional calibration models during the past few decades. It is now possible to apply precise TCND even to young landforms like Late Holocene moraines, a task seemed hardly achievable just about 15 years ago. An increasing number of studies provide very precise TCND ages for boulders from Late Holocene moraines enabling related reconstruction of glacier chronologies and the interpretation of these glacial landforms in a palaeoclimatological context. These studies may also solve previous controversies about different ages assigned to moraines obtained by different dating techniques, for example relative-age dating techniques or techniques combining relative-age dating with few fixed points derived from numerical age dating. There are a few cases, for example Mueller Glacier and nearby long debris-covered valley glacier in Aoraki/Mt.Cook National Park (Southern Alps, New Zealand), where the apparent "supremacy" of TCND-ages seem to overrule glacial geomorphological principles. Enabled by a comparatively high number of individual boulders precisely dated by TCND, moraine ridges on those glacier forelands have been primarily clustered on basis of these boulder ages rather than on their corresponding morphological position. To the extreme, segments of a particular moraine complex morphologically and sedimentologically proven to be formed during one event have become split and classified as two separate "moraines" on different parts of the glacier foreland. One ledge of another moraine complex contains 2 TCND-sampled boulders apparently representing two separate "moraines"-clusters of an age difference in the order of 1,500 years. Although recently criticism has been raised regarding the non-contested application of the arithmetic mean for calculation of TCND-ages for individual moraines, this

  11. Factors controlling carbon isotopic composition of land snail shells estimated from lab culturing experiment

    Science.gov (United States)

    Zhang, Naizhong; Yamada, Keita; Yoshida, Naohiro

    2014-05-01

    contribution of different carbon sources for each snail individual: to cabbage (C3 plant) fed groups, the contributions of diet, atmospheric CO2 and ingested limestone vary in a range of 66~80%, 16~24% and 0~13%, respectively. And to corn (C4 plant) fed groups, because of the possible food stress (lower consumption ability of C4 plant), they vary in 56~64%, 18~20% and 16~26%, respectively. We will discuss how these results could be consistent to the observations, which suggests our calculations are suitable and believable. In addition, we will discuss the carbon isotope fractionation during egg laying and hatching of land snails, too. [1] Goodfriend, 1992, Quaternary Sciences Reviews. 11, 665-685 [2] Yanes et al. 2009. Geochimica et Cosmochimica Acta, 73, 4077-4099 [3] Yanes et al., 2013. Palaeogeography, Plaeoclimatology, Palaeoecology, 378, 91-102 [4] Goodfriend and Hood, 1983. Radiocarbon, 25, 810-830 [5] Goodfriend and Stipp, 1983. Geology, 11, 575-577 [6] Stott, 2002. Earth and Planetary Science Letters, 195, 249-259 [7] Metref et al., 2003. Earth and Planetary Science Letters, 211, 381-393 [8] Romaniello et al., 2008. Quaternary Geochronology, 3, 68-75

  12. Distributional patterns of decapod crustaceans in the circum-Mediterranean area during the Oligo-Miocene

    Science.gov (United States)

    Hyžný, Matúš

    2015-04-01

    . 80, 83-103. Harzhauser M., Kroh A., Mandic O., Piller W.E., Göhlich U., Reuter M. & Berning B. 2007: Biogeographic responses to geodynamics: a key study all around the Oligo-Miocene Tethyan Seaway. Zool. Anz. 246, 241-256. Harzhauser M., Mandic O. & Zuschin M. 2003: Changes in Paratethyan marine molluscs at the Early/Middle Miocene transition: diversity, palaeogeography and palaeoclimate. Acta Geol. Pol. 53, 323-339. Harzhauser M., Piller W.E. & Steininger F.F. 2002: Circum-Mediterranean Oligo/Miocene Biogeographic Evolution - the Gastropods' Point of View. Palaeogeogr., Palaeoclimatol., Palaeoecol. 183, 103-133. Müller P. 1979: The Indo-West-Pacific character of the Badenian decapod crustaceans of the Paratethys. In: VII International Congress on Mediterranean Neogene. Athens, September 27-October 2. Ann. Géol. Pays Hellén., Tome hors série 2, 865-869. Schweitzer C.E. 2001: Paleobiogeography of Cretaceous and Tertiary decapod crustaceans of the North Pacific Ocean. J. Paleontol. 75, 808-826. Studencka B., Gontsharova I.A. & Popov S.V. 1998: The bivalve faunas as a basis for reconstruction of the Middle Miocene history of the Paratethys. Acta Geol. Pol. 48, 285-342.

  13. An outline of the palaeogeographic evolution of the Australasian region since the beginning of the Neoproterozoic

    Science.gov (United States)

    Li, Z. X.; Powell, C. McA.

    2001-04-01

    In the last 1000 million years, Australia has been part of two supercontinents: Palaeozoic Gondwanaland and Neoproterozoic Rodinia. Neoproterozoic Australia was covered by shallow epicontinental seas, and, in the late Neoproterozoic, by low-latitude glaciers. The breakup of Rodinia along the Tasman Line occurred at the end of the Sturtian glaciation (760 Ma) giving rise to the Palaeo-Pacific Ocean. Gondwanaland formed in the Early Cambrian, at the same time as the Tarim block broke away from northwestern Australia. Westward subduction of the Palaeo-Pacific Ocean along the eastern margin of Australia-Antarctica commenced during the Early Cambrian in northern Victoria Land and in the Middle Cambrian in South Australia, and culminated to the Late Cambrian-Early Ordovician Ross-Delamerian Mountains. In the Ordovician, the magmatic arc retreated from Australia's then-eastern continental margin, forming a marginal sea and offshore island arc. A shallow seaway across Australia in the Late Cambrian and Ordovician gradually gave way to desert-like conditions in Central Australia and the adjacent Canning Basin by Silurian time. The Silurian to mid-Devonian was an interval of rapidly changing palaeogeography in eastern Australia with deep volcanogenic troughs formed in a dextral transtensional tectonic setting. Widespread deformation in the Tasman orogenic zone in the Middle Devonian to Early Carboniferous, was accompanied by the development of an Andean-style magmatic arc along the Pacific continental margin of Australia. The most widespread Phanerozoic mountain-building stage in Central Australia occurred in the Late Devonian to mid-Carboniferous, as part of a world-wide Variscan orogenic episode associated with the collision of Gondwanaland with Laurussia to form Pangea. In the late Visean, Australia drifted rapidly southward from previous low latitudes to a near-polar position. Glacial conditions dominated the Late Carboniferous and earliest Permian. Transtensional basins

  14. Palaeoenvironmental drivers of vertebrate community composition in the Belly River Group (Campanian) of Alberta, Canada, with implications for dinosaur biogeography.

    Science.gov (United States)

    Cullen, Thomas M; Evans, David C

    2016-11-15

    The Belly River Group of southern Alberta is one of the best-sampled Late Cretaceous terrestrial faunal assemblages in the world. This system provides a high-resolution biostratigraphic record of terrestrial vertebrate diversity and faunal turnover, and it has considerable potential to be a model system for testing hypotheses of dinosaur palaeoecological dynamics, including important aspects of palaeoecommunity structure, trophic interactions, and responses to environmental change. Vertebrate fossil microsites (assemblages of small bones and teeth concentrated together over a relatively short time and thought to be representative of community composition) offer an unparalleled dataset to better test these hypotheses by ameliorating problems of sample size, geography, and chronostratigraphic control that hamper other palaeoecological analyses. Here, we assembled a comprehensive relative abundance dataset of microsites sampled from the entire Belly River Group and performed a series of analyses to test the influence of environmental factors on site and taxon clustering, and assess the stability of faunal assemblages both temporally and spatially. We also test the long-held idea that populations of large dinosaur taxa were particularly sensitive to small-scale environmental gradients, such as the paralic (coastal) to alluvial (inland) regimes present within the time-equivalent depositional basin of the upper Oldman and lower Dinosaur Park Formations. Palaeoenvironment (i.e. reconstructed environmental conditions, related to relative amount of alluvial, fluvial, and coastal influence in associated sedimentary strata) was found to be strongly associated with clustering of sites by relative-abundance faunal assemblages, particularly in relation to changes in faunal assemblage composition and marine-terrestrial environmental transitions. Palaeogeography/palaeolandscape were moderately associated to site relative abundance assemblage clustering, with depositional setting

  15. The landslide problem

    Directory of Open Access Journals (Sweden)

    G. Shanmugam

    2015-04-01

    Full Text Available The synonymous use of the general term “landslide”, with a built-in reference to a sliding motion, for all varieties of mass-transport deposits (MTD, which include slides, slumps, debrites, topples, creeps, debris avalanches etc. in subaerial, sublacustrine, submarine, and extraterrestrial environments has created a multitude of conceptual and nomenclatural problems. In addition, concepts of triggers and long-runout mechanisms of mass movements are loosely applied without rigor. These problems have enormous implications for studies in process sedimentology, sequence stratigraphy, palaeogeography, petroleum geology, and engineering geology. Therefore, the objective of this critical review is to identify key problems and to provide conceptual clarity and possible solutions. Specific issues are the following: (1 According to “limit equilibrium analyses” in soil mechanics, sediment failure with a sliding motion is initiated over a shear surface when the factor of safety for slope stability (F is less than 1. However, the term landslide is not meaningful for debris flows with a flowing motion. (2 Sliding motion can be measured in oriented core and outcrop, but such measurement is not practical on seismic profiles or radar images. (3 Although 79 MTD types exist in the geological and engineering literature, only slides, slumps, and debrites are viable depositional facies for interpreting ancient stratigraphic records. (4 The use of the term landslide for highvelocity debris avalanches is inappropriate because velocities of mass-transport processes cannot be determined in the rock record. (5 Of the 21 potential triggering mechanisms of sediment failures, frequent short-term events that last for only a few minutes to several hours or days (e.g., earthquakes, meteorite impacts, tsunamis, tropical cyclones, etc. are more relevant in controlling deposition of deep-water sands than sporadic long-term events that last for thousands to millions of

  16. Record of Carcharocles megalodon in the Eastern Guadalquivir Basin (Upper Miocene, South Spain

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    Reolid, M.

    2015-12-01

    Full Text Available Tortonian diatomites of the San Felix Quarry (Porcuna, in the Eastern Guadalquivir Basin, have given isolated marine vertebrate remains that include a large shark tooth (123.96 mm from apex to the baseline of the root. The large size of the crown height (92.2 mm, the triangular shape, the broad serrated crown, the convex lingual face and flat labial face, and the robust, thick angled root determine that this specimen corresponds to Carcharocles megalodon. The symmetry with low slant shows it to be an upper anterior tooth. The total length estimated from the tooth crown height is calculated by means of different methods, and comparison is made with Carcharodon carcharias. The final inferred total length of around 11 m classifies this specimen in the upper size range of the known C. megalodon specimens. The palaeogeography of the Guadalquivir Basin close to the North Betic Strait, which connected the Atlantic Ocean to the Mediterranean Sea, favoured the interaction of the cold nutrient-rich Atlantic waters with warmer Mediterranean waters. The presence of diatomites indicates potential upwelling currents in this context, as well as high productivity favouring the presence of large vertebrates such as mysticetid whales, pinnipeds and small sharks (Isurus. These large vertebrates recorded in the Eastern Guadalquivir Basin were potential prey of C. megalodon.Las diatomitas tortonienses de la antigua Cantera de San Félix (Porcuna, Jaén, en el sector oriental de la Cuenca del Guadalquivir, han proporcionado restos aislados de vertebrados marinos entre los que destaca un gran diente de tiburón (123.96 mm desde el ápice hasta la línea basal de la raiz. La altura de la corona (92.2 mm, su forma triangular con bordes aserrados, la presencia de una cara lingual convexa y una labial plana, conjuntamente con la raíz angulosa y robusta, permiten determinar que este diente perteneció a un ejemplar de Carcharocles megalodon. La alta simetría de la pieza

  17. Tectonic structure and evolution of Eastern Anatolia - insights from new petrologic data and possible lateral correlations

    Science.gov (United States)

    Oberhänsli, Roland; Pourteau, Amaury; Candan, Osman; Bousquet, Romain; Çetinkaplan, Mete; Koralay, Ersin

    2013-04-01

    Modern Eastern Anatolia is a high-plateau region characterized by active N-S crustal shortening, mostly accommodated along strike-slip faults, and recent, abundant volcanism. Due to the extensive Cenozoic marine and Quaternary volcano-sedimentary covers, Tetyhan palaeogeography and related tectonic settings, and thence their impact on modern strain partitioning, in this region are particularly difficult to unravel, and therefore remains strongly debated. According to recent works in Armenia and northernmost Eastern Anatolia, blueschists dated to middle Cretaceous times record the accretion of the South-Armenian Block to the southern Eurasian margin, now separated by the Sevan-Akera Suture. Further south, we recently documented Late Cretaceous HP-LT metamorphism in the Bitlis Complex, which belongs to a micro-continental block isolated between the South-Armenian Block and the Arabian Platform. In order to gain further insights into Eastern Anatolia's tectonic architecture, and its continuation into the better-established Central and Western Anatolian tectonic domains, we collected petrologic data from slightly- to strongly metamorphosed sedimentary and crustal lithologies of scattered localities of SE Anatolia, west and north of the Bitlis Complex. From our field observations, we report only low-grade metamorphic assemblages in metasedimentary rocks of the Pütürge Massif, which was commonly considered as the western equivalent of the Bitlis Massif, but obviously did, in contrast to the latter, not experienced HP-LT metamorphism. Nevertheless, glaucophane-bearing rocks were found farther west, north of Adıyaman, might represent the west continuation of the Bitlis HP Complex. From near Malatya, north of the Pütürge Massif and south of the Eastern Tauride non-metamorphosed carbonate platform, eastwards via Elazig and Bingöl, to Aǧrı, between the Bitlis Massif and the South-Armenian Block, we found numerous, scattered occurrences of HT metamorphic assemblages in

  18. Metamorphic belts of Anatolia

    Science.gov (United States)

    Oberhänsli, Roland; Prouteau, Amaury; Candan, Osman; Bousquet, Romain

    2015-04-01

    Investigating metamorphic rocks from high-pressure/low-temperature (HP/LT) belts that formed during the closure of several oceanic branches, building up the present Anatolia continental micro-plate gives insight to the palaeogeography of the Neotethys Ocean in Anatolia. Two coherent HP/LT metamorphic belts, the Tavşanlı Zone (distal Gondwana margin) and the Ören-Afyon-Bolkardağ Zone (proximal Gondwana margin), parallel their non-metamorphosed equivalent (the Tauride Carbonate Platform) from the Aegean coast in NW Anatolia to southern Central Anatolia. P-T conditions and timing of metamorphism in the Ören-Afyon-Bolkardağ Zone (>70?-65 Ma; 0.8-1.2 GPa/330-420°C) contrast those published for the overlying Tavşanlı Zone (88-78 Ma; 2.4 GPa/500 °C). These belts trace the southern Neotethys suture connecting the Vardar suture in the Hellenides to the Inner Tauride suture along the southern border of the Kirşehir Complex in Central Anatolia. Eastwards, these belts are capped by the Oligo-Miocene Sivas Basin. Another HP/LT metamorphic belt, in the Alanya and Bitlis regions, outlines the southern flank of the Tauride Carbonate Platform. In the Alanya Nappes, south of the Taurides, eclogites and blueschists yielded metamorphic ages around 82-80 Ma (zircon U-Pb and phengite Ar-Ar data). The Alanya-Bitlis HP belt testifies an additional suture not comparable to the northerly Tavşanlı and Ören-Afyon belts, thus implying an additional oceanic branch of the Neotethys. The most likely eastern lateral continuation of this HP belt is the Bitlis Massif, in SE Turkey. There, eclogites (1.9-2.4 GPa/480-540°C) occur within calc-arenitic meta-sediments and in gneisses of the metamorphic (Barrovian-type) basement. Zircon U-Pb ages revealed 84.4-82.4 Ma for peak metamorphism. Carpholite-bearing HP/LT metasediments representing the stratigraphic cover of the Bitlis Massif underwent 0.8-1.2 GPa/340-400°C at 79-74 Ma (Ar-Ar on white mica). These conditions compares to the Tav

  19. XRF core scanners as a quick and good screening tool for detecting pollution in sediment cores

    Directory of Open Access Journals (Sweden)

    Belén Rubio

    2014-05-01

    Full Text Available The capabilities of X-Ray Fluorescence (XRF core scanners, to acquire high-resolution geochemical data sets in relatively short time, have made them an increasingly popular geochemical screening tool to study sediment cores for palaeoclimatologic and palaeoceanographic purposes (Peck et al., 2007; Rebolledo et al., 2008. These scanners are able to obtain optical images, X-ray radiographs, and continuous geochemical data with a maximum resolution of 200 µm directly from sediment cores (Croudace et al., 2006. Geochemical results are obtained as peak areas of counts per second that are proportional to element concentrations in the sediment, and thus the assumed semi-quantitative nature of these analyses have hampered the use of this type of instruments to monitor and detect pollution at large; where the availability of a fast screening tool that could substantially cut analytical and time costs will certainly be an advantage. This study explores the sensitivity of a ITRAX core scanner (Cox Analytical Systems on sedimentary records from estuarine-like environments in NW (Rías Baixas Galicia and SW Spain (Ría de Huelva. The Galician Rías Baixas sediments are characterized by high contents of organic matter, but in general terms, are not heavily polluted. We have selected one core in the Marín harbour (Ría de Pontevedra and another in the intertidal area of San Simón Bay (inner Ría de Vigo, close to a ceramic factory, which is relatively highly polluted by lead. By the contrary, the Ría de Huelva is one of the most polluted areas in western Europe because of the high acid mining activity together with the chemical industries located in its margins. We have selected a core in the Padre Santo Channel in the confluence of the Odiel and Tinto rivers. ITRAX sensitivity was obtained by establishing equivalences between peak areas and concentrations obtained by traditional analytical techniques such as ICP-MS, ICP-OES and/or conventional XRF of

  20. Land - Ocean Climate Linkages and the Human Evolution - New ICDP and IODP Drilling Initiatives in the East African Rift Valley and SW Indian Ocean

    Science.gov (United States)

    Zahn, R.; Feibel, C.; Co-Pis, Icdp/Iodp

    2009-04-01

    The past 5 Ma were marked by systematic shifts towards colder climates and concomitant reorganizations in ocean circulation and marine heat transports. Some of the changes involved plate-tectonic shifts such as the closure of the Panamanian Isthmus and restructuring of the Indonesian archipelago that affected inter-ocean communications and altered the world ocean circulation. These changes induced ocean-atmosphere feedbacks with consequences for climates globally and locally. Two new ICDP and IODP drilling initiatives target these developments from the perspectives of marine and terrestrial palaeoclimatology and the human evolution. The ICDP drilling initiative HSPDP ("Hominid Sites and Paleolakes Drilling Project"; ICDP ref. no. 10/07) targets lacustrine depocentres in Ethiopia (Hadar) and Kenya (West Turkana, Olorgesailie, Magadi) to retrieve sedimentary sequences close to the places and times where various species of hominins lived over currently available outcrop records. The records will provide a spatially resolved record of the East African environmental history in conjunction with climate variability at orbital (Milankovitch) and sub-orbital (ENSO decadal) time scales. HSPDP specifically aims at (1) compiling master chronologies for outcrops around each of the depocentres; (2) assessing which aspects of the paleoenvironmental records are a function of local origin (hydrology, hydrogeology) and which are linked with regional or larger-scale signals; (3) correlating broad-scale patterns of hominin phylogeny with the global beat of climate variability and (4) correlating regional shifts in the hominin fossil and archaeological record with more local patterns of paleoenvironmental change. Ultimately the aim is to test hypotheses that link physical and cultural adaptations in the course of the hominin evolution to local environmental change and variability. The IODP initiative SAFARI ("Southern African Climates, Agulhas Warm Water Transports and Retroflection

  1. Siberia, the wandering northern terrane, and its changing geography through the Palaeozoic

    Science.gov (United States)

    Cocks, L. Robin M.; Torsvik, Trond H.

    2007-05-01

    alternatives that result in two very different convergence scenarios between Siberia and Baltica/Kazakh terranes. There are a newly-constructed succession of palaeogeographic maps of Siberia and its nearby areas at various times from the Cambrian to the Permian as, firstly, the peri-Siberian terranes and, secondly, the remainder of the Central Asian terranes accreted to it. Prior to the Early Ordovician, Siberia was in the southern hemisphere, but after that it drifted northwards and for most of the Phanerozoic it has been one of the few larger terranes in the northern hemisphere. The Cambrian and Ordovician maps are provisional for the Altai-Sayan and Mongolian areas, whose geology is highly complex and whose detailed palaeogeography is unresolved. The terms "Altaids" and "Paleo-Asian Ocean" have been used in so many different ways by so many different authors over so many geological periods that we reject their use. Wider issues considered include the possible links between the Cambrian Radiation (often wrongly termed "Explosion"), when metazoan animals first gained hard parts, and True Polar Wander (TPW). New Early Cambrian palaeomagnetic data from Siberia do not show rapid APW (< 10 cm/yr.) or dramatic velocity changes (< 4 cm/yr). It is concluded that the Cambrian Radiation occurred over a period approaching 20 Myr, and that rapid and large-scale TPW did not take place in the Cambrian. In addition, there are no traces of glaciogenic deposits in the very large area of Siberia during the Neoproterozoic, casting some doubt on the "Snowball Earth" hypothesis.

  2. A reevaluation of the lineage development of Pararotalia and Praepararotalia including new material from the Rupelian of the southern Upper Rhine Graben

    Science.gov (United States)

    Pirkenseer, C.; Spezzaferri, S.

    2009-04-01

    in Brazilian coastal and paralic environments. - Journal of Foraminiferal Research, 31, 2: 152-163. HOTTINGER, L., HALICZ, E. & REISS, Z. (1991): The foraminiferal genera Pararotalia, Neorotalia, and Calcarina: taxonomic revision. - Journal of Paleontology, 65, 1: 18-33. LIU, C., OLSSON, R. K. & HUBERT, B. T. (1998): A benthic paleohabitat for Praepararotalia gen. nov. and Antarcticella Loeblich and Tappan. - Journal of Foraminiferal Research, 28, 1: 3-18. MANCIN, N., PIRINI, C. & LANFRANCHINI, P.L. (2000): New species of Pararotalia LE CALVEZ, in Pliocene sediments of the Lower Valsesia and Western Liguria. - Bollettina della Società Paleontologica Italiana, 39, 3: 341-350. PIRKENSEER, C. (2007): Foraminifera, Ostracoda and other microfossils of the Southern Upper Rhine Graben - Palaeoecology, biostratigraphy, palaeogeography and geodynamic implications. - PhD thesis: 340p, Fribourg.

  3. Reworked planktonic Foraminifera from the Late Rupelian of the southern Upper Rhine Graben and their palaeogeographic and biostratigraphic implications

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    Pirkenseer, C.; Spezzaferri, S.; Berger, J.-P.

    2009-04-01

    margin of the Upper Rhine Graben. Reworked Mesozoic and Paleogene calcareous nannoplankton from the Upper Rhine Graben and the Mainz Basin confirms the data derived from planktonic Foraminifera. The existence of reworked planktonic Foraminifera influences the biostratigraphic interpretation of the assemblage ranges attributed to "Série grise" samples. Facultatively reworked planktonic Foraminifera as Subbotina utilisindex and Pseudohastigerina micra ranging from the Lutetian to the Late Rupelian should not be included in the biostratigraphic analyses, as the occurrences of these facultatively reworked species are always linked to those of exclusively Cretaceous and Eocene age. Therefore the age of the "Série grise" deposits at Allschwil-2 is most likely to be placed within the "Chiloguembelina cubensis - Globigerinella obesa / Globorotaloides variabilis"-assemblage range of Mid P20 to Final P21a, lasting considerably longer than the very short Mid P20 range based on the presence of Pseudohastigerina micra as "last occurrence"-marker (PIRKENSEER 2007). This study was funded by the Swiss National Science Foundation projects 109457 and 118025. References: BERGER, J.-P., REICHENBACHER, B., BECKER, D., et al. (2005): Eocene-Pliocene time scale and stratigraphy of the Upper Rhine Graben (URG) and the Swiss Molasse Basin (SMB). - International Journal of Earth Sciences, 94, 4: 711-731. FISCHER, H. (1965): Geologie des Gebietes zwischen Blauen und Pfirter Jura. - Beiträge zur geologischen Karte der Schweiz, NF 122: 106p. PIRKENSEER, C. (2007): Foraminifera, Ostracoda and other microfossils of the Southern Upper Rhine Graben - Palaeoecology, biostratigraphy, palaeogeography and geodynamic implications. - PhD thesis: 340p, Fribourg. ROUSSÉ, S. (2006): Architecture et dynamique des séries marines et continentales de ĺOligocène Moyen et Supérieur du Sud du Fossé Rhénan: Evolution des milieux de dépôt en contexte de rift en marge de ĺavant-pays alpin. - PhD: 471p

  4. Higher-order phylogeny of modern birds (Theropoda, Aves: Neornithes) based on comparative anatomy. II. Analysis and discussion

    Science.gov (United States)

    LIVEZEY, BRADLEY C; ZUSI, RICHARD L

    2007-01-01

    Piciformes. Unresolved portions of the Neornithes (nodes having more than one most-parsimonious solution) comprised three parts of the tree: (a) several interfamilial nodes within the Charadriiformes; (b) a trichotomy comprising the (i) Psittaciformes, (ii) Columbiformes and (iii) Trogonomorphae (Trogoniformes, Coliiformes) + Passerimorphae (Coraciiformes, Piciformes, Passeriformes); and (c) a trichotomy comprising the Coraciiformes, Piciformes and Passeriformes. The remaining polytomies were among outgroups, although several of the highest-order nodes were only marginally supported; however, the majority of nodes were resolved and met or surpassed conventional standards of support. Quantitative comparisons with alternative hypotheses, examination of highly supportive and diagnostic characters for higher taxa, correspondences with prior studies, complementarity and philosophical differences with palaeontological phylogenetics, promises and challenges of palaeogeography and calibration of evolutionary rates of birds, and classes of promising evidence and future directions of study are reviewed. Homology, as applied to avian examples of apparent homologues, is considered in terms of recent theory, and a revised annotated classification of higher-order taxa of Neornithes and other closely related Theropoda is proposed. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 149, 1–95. PMID:18784798

  5. Rb-Sr and Nd-Sr isotope geochemistry and petrogenesis of the Misho Mountains mafic dikes (NW Iran

    Directory of Open Access Journals (Sweden)

    Maryam Ahankoub

    2017-02-01

    the mafic dike. Discussion Geochemistry data indicate that Misho mafic dikes are similar to calc-alkaline basalts of the oceanic island basalts (OIB whereas Nb and Ti negative anomalies of the trace elements patterns are similar to crustal contamination. Negative amount of the εNd(T indicated depleted mantel source (array mantel with some continental crust contamination during AFC processes . Base on the results of analysis, the upper crust is the best candidates for magma contamination of the mafic dikes in Misho. Isotopic data indicated to replace mafic dike 232ma years ago by closing of paleotethys and forming the extension zone (break up in active continental margin. Acknowledgement We thank Professor Yamamoto, head of geochemistry department of the Nagoya University for help .We are grateful to professor Karimpour, Chief Editor of the Journal of Economic Geology, and three anonymous reviewers for their constructive suggestions and comments. Reference Ahankoub, M., 2012. Petrogenesis and geochemistry east Misho granitoides (NW of Iran. Ph.D. Thesis, Tabriz University, Tabriz, Iran, 171 pp. (in Persian with English abstract Eftekharnejad, J., 1981. Tectonic division of Iran with respect to sedimentary basins. Journal of Iran Petroleum Society, 82(3: 19–28. (in Persian with English abstract Martin, H, 1999. Adakitic magmas: modern analogues of Archaean granitoids. Lithos, 46(3: 411–429. Metcalfe, I., 2006. Paleozoic and Mesozoic tectonic evolution and palaeogeography of East Asian crustal fragments: the Korean Peninsula in context. Gondwana Research, 9(1-2: 24–46. Moayyed, M. and Hossainzade, G., 2011. Petrology and petroghraphy of A- type Granitoides of the East-Misho Mountain with theory on its geodynamic importance. Journal of Mineralogy and Crystalography, 3(19: 529–544. (in Persian with English abstract Sun, S.S. and McDonough, W.F., 1989. Chemical and isotopic systematic of ocean basalts: implications for mantle composition and process. In: A

  6. Petrogenesis and zircon U-Pb dating of skarnified pyroxene-bearing dioritic rocks in Bisheh area, south of Birjand, eastern Iran

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    Malihe Nakhaei

    2014-10-01

    during the melting of the source (Reagan and Gill, 1989. This pattern followed that of calc-alkaline magmas derived from a sub-arc mantle, with scarce or no garnet in the source. Furthermore, Bisheh subvolcanic bodies were enriched in Rb, Ba and Th, indicating that they had experienced interaction with the continental crust (Kuşcu et al., 2002. The chondrite-normalized rare earth element pattern of the studied rocks shows a high ratio of light rare earth elements (LREE to heavy rare earth elements (HREE. All the samples have been plotted in the VAG field. The dioritic rocks from the Bisheh have relatively high Mg# (0.4-0.56, which is consistent with derivation from mantle melts contaminated by continental crust (Rapp and Watson, 1995. The initial 87Sr/86Sr of Bisheh pyroxene diorite porphyry was 0.70606 and the (143Nd/144Ndi isotope compositions and εNd value of these rocks was 0.512424 and -3.05, respectively. These values show that the magma originated from an enriched mantle with crustal contamination. Acknowledgements The authors are grateful to Professor Sun-Lin Chung from the Department of Geosciences, National Taiwan University, for supporting the researchers in the use of U-Th-Pb zircon age dating. References Berberian, M. and King, G.C., 1981. Towards a palaeogeography and tectonics evolution of Iran. Canadian Journal of Earth Science, 18(2: 210–265. Esmaeily, D., Nedelec, A., Valizadeh, M.V., Moore, F. and Cotton, J., 2005. Petrology of the Jurassic Shah-Kuh granite (eastern Iran, with reference to tin mineralization. Journal of Asian Earth Sciences, 25(6: 961-980. Tarkian, M., Lotfi, M. and Baumann, A., 1983. Tectonic, magmatism and the formation of mineral deposits in the central Lut, east Iran. Geological Survey of Iran, geodynamic project (geotraverse in Iran, Tehran, Report 51, 519 pp. Moradi Noghondar, M., Karimpour, M.H., Farmer, G.L. and Stern, C.R., 2011-2012. Sr-Nd isotopic characteristic, U-Pb zircon geochronology, and petrogenesis of Najmabad

  7. Pleistocene lake level changes in Western Mongolia

    Science.gov (United States)

    Borodavko, P. S.

    2009-04-01

    .Petersburg, Nauka, 304 p. 4. Tarasov, P.E., Harrison, S.P., Saarse, L., Pushenko, M.Ya., Andreev, A.A., Aleshinskaya, Z.V., Davydova, N.N., Dorofeyuk, N.I., Efremov, Yu.V., Khomutova, V.I., Sevastyanov, D.V., Tamosaitis, J., Dorofeyuk, N.I., Efremov, Yu.V., Khomutova, V.I., Sevastyanov, D.V., Tamosaitis, J.,Uspenskaya, O.N., Yakushko, O.F. and Tarasova, I.V., 1994. Lake status records from the Former Soviet Union and Mongolia: Data Base Documentation, World Data Center -A for Paleoclimatology NOAA Paleoclimatology Program, Paleoclimatology Publications Series Report No 2, Boulder, Colorado USA, 274 p. 5. Tserensodnom, Zh., 1971. Mongol orny Nuur. Ulaanbaatar, TUAH, 202 p. 6. Vipper, P., Dorofeyuk, N., Liiva, A., Meteltseva, E., and Sokolovskaya, V., 1981. Palaeogeography of the Central Mongolia during the upper Pleistocene and Holocene. Izv. Akad. Nauk ESSR, Ser. Biol., vol. 30, no. 1, pp. 74-82.

  8. Braidplain, floodplain and playa lake, alluvial-fan, aeolian and palaeosol facies composing a diversified lithogenetical sequence in the permian and triassic of South Devon (England)

    Science.gov (United States)

    Mader, Detlef

    and neoformation of mud during illuviation, conversion of colour to blue-violet by significant hematite growth and pedoturbation being frequently restricted to the initial stages or even being totally suppressed. Root tubes testify to the colonization of soils by vegetation. Crystallization of syngenetic carbonates in aeolian sands forming dikaka horizons is of considerable importance for enhancing their preservation potential by stabilization against both fluvial erosion and aeolian deflation. The coexistence of aeolian sands and calcrete palaeosols (in contrast to their mutually exclusive occurrence in the Upper Buntsandstein of the German Basin) is the result of the limited maturity of the pedogenic horizons with preservation of sandy matrix thus still permitting reasonable winnowing at least in parts of the depositional area, and restriction of atmospheric precipitation to shorter phases alternating with longer dry periods that allow desiccation of the surface and migration of aeolian bedforms. Bröckelbank carbonate breccias representing reworking horizons of calcrete palaeosols are indirect indicators of pedogenesis in the alluvial plain even in case of subsequently complete removal of in situ pedogenic features from the depositional record. Calcrete palaeosol formation overprints almost all the sedimentary units in the alluvial plain regardless of their composition, but is particularly frequent and well-developed in fluvial and aeolian substrates. The sequence of alluvial fans and fluvial braidplains with associated aeolian dune fields and intertonguing with fluvial floodplains to playa lakes in time and space, interrupted by various palaeotectonical and palaeoclimatological events, results in a very diversified depositional history in the Permian and Triassic part of the New Red Sandstone in South Devon.