DOCSLIB.ORG

Quantified Middle Jurassic to Paleocene Eustatic Variations Based on Russian Platform Stratigraphy: Stage Level Resolution

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Quantified Middle Jurassic to Paleocene Eustatic Variations Based on Russian Platform Stratigraphy: Stage Level Resolution Quantified Middle Jurassic to Paleocene eustatic variations based on Russian Platform stratigraphy: Stage level resolution DORK SAHAGIAN Department of Geological Sciences and Byrd Polar Research Center, The Ohio State University, Columbus, Ohio 43210 MICHELLE JONES Department of Geological Sciences, The Ohio State University, Columbus, Ohio 43210 ABSTRACT With regard to the first problem, we define eustasy as the relation between the volumes of the ocean basins and total ocean water. A We have constructed a eustatic sea-level curve based on the stra- change in this relationship would affect all ocean-continental bound- tigraphy of the tectonically stable Russian Platform. Sea-level variations aries (shorelines) equally, and be modulated by local epeirogenic and measured against this reference frame were chosen as reliably repre- other tectonic activity. The second problem is more complicated, not senting the long-term relation of global ocean-basin volume and ocean- being subject to simple definition, but is an outgrowth of the first and water volume. In constructing the curve, we bacfcstripped stratigraphic is the primary concern of this paper. Stratigraphic successions evolve data from numerous wells distributed across the Russian Platform and in response to relative sea-level change, a function of both eustasy and then used the present elevation of various stratigraphic horizons to tie the tectonics (Posamentier and others, 1988), and so the stratigraphic resulting curve to present sea level. Most strata observed represent very record can be used to measure sea level. If tectonic events are insig- shallow water deposition (<25 m), and so we were able to estimate nificant, then relative sea-level events will be caused solely by eustatic water-depth variations more reliably than would have been possible in events. Consequently, stratigraphy on demonstrably stable platform a deep-water environment. The stratigraphy of the Russian Platform is areas should provide a reliable indication of eustatic change. riddled with unconformities. This is a result of the ability of even minor Lithofacies distributions in clastic environments (particularly eustatic fluctuations to cause sea level to drop off the platform. These grain size) are controlled largely by the distance of sites of sediment unconformities are important in accurately fixing sea level (0 water deposition from terrestrial sediment sources. One way to observe depth) at various times throughout the late Mesozoic-eariiest Tertiary. sea-level changes is through their effect on sedimentation patterns The eustatic curve resulting from this study indicates that sea level rose along continental margins (Jervey, 1988; Posamentier and others, by 120 m from the mid-Jurassic (60 m above present) to the mid-Cre- 1988; Posamentier and Vail, 1988). This relationship is affected by sea taceous (180 m above present) and remained at about that level until the level according to the hypsometiy of the relevant continental margin, Tertiary, when it began to drop. The long-term rise was not uniform, which also affects the areal distribution of water depth. In marginal but spasmodic, with many shorter-term eustatic rises and falls. These environments, however, it is difficult to quantify the epeirogenic ac- events had magnitudes of tens of meters over timescales of 1 to 5 m.y. tivity at the level of precision necessary to distinguish tectonic from The causative mechanism for these variations is not clear. The eustatic eustatic controls on facies distributions and depositional sequences. curve resulting from this study can be applied to subsiding basins and Consequently, in order to measure eustasy, it is useful to find a ref- passive margins in order to quantify subsidence history. erence frame such as a stable platform against which stratigraphic and other eustatic signals will accurately reflect the relative volumes of INTRODUCTION ocean water and basins, rather than local tectonic or epeirogenic processes. Many authors noticed long ago (Davis 1896; Johnson, 1919; Bal- Stable continental regions can be found on the basis of flat-lying chin, 1937; Miller, 1939) that sea level has not been invariant and otherwise undeformed strata in North America (Sloan, 1964; throughout Earth history. Long-term sea-level changes (>1 m.y.) Sleep, 1976; Merewether, 1983; Sahagian, 1987), Africa (Sahagian, have been observed qualitatively through their effect on the deposi- 1988), and the Russian Platform (Aleinikov and others, 1980; Sa- tional patterns and shoreline processes of marine fades. The quanti- hagian, 1989). The North American and African regions are limited in fication of sea-level variations, however, has been hampered by two their stratigraphic range, including only some Upper Cretaceous de- fundamental problems (Sahagian and Holland, 1991). The first is a posits. The Russian Platform, however (Fig. 1), owing to its elevation classically unclear definition of the term "sea level," making it difficult in the Mesozoic, has preserved shallow-water deposits ranging in age to choose an actual quantity to measure. The second is inaccuracy in from Middle Jurassic through Upper Cretaceous, and even includes measurement methods which are based on depositional and other Paleogene sediments in one area. It is thus much more useful for consequences of sea-level changes as observed in various tectonic constructing a truly eustatic sea-level curve than are the other con- environments. tinental regions. It is also more reliable, including a larger stable area Data Repository item 9319 contains additional material related to this article. Geological Society of America Bulletin, v. 105, p. 1109-1118, 5 figs., 1 table, August 1993. 1109 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/105/8/1109/3381872/i0016-7606-105-8-1109.pdf by guest on 30 September 2021 SAHAGIAN JSTD JONES as defined by the preserved sediments (Sahagian, 1989; Sahagian and the absence of thick coarse terrigenous sediments. Besides the im- Holland, 1991). This is contrary to the interpretation of some Russian plication that such deep water would require (nonglacial) sea-level investigators who have assumed that all transgressions and regres- changes at possibly unreasonable rates (tens of m/m.y.), the uniform- sions as well as associated facies variations were caused by uplift and ity of sediment thicknesses across the Russian Platform (regardless of subsidence and that by implication, sea level has remained constant lithology or proximity to clastic sources) suggests that deposition was throughout the Mesozoic-Cenozoic (Nalivkin, 1976; Aleinikov and not occurring very far below base level. This is in contrast to results others, 1980). Some have also used present outcrop extent as the full of preliminary analyses of adjacent subsiding basins, where there are region of deposition (Vinogradov, 1968) and have constructed hyp- large variations in thickness, associated with lithology, and interpreted sometric curves on that basis to account for tectonic history, not as lateral variations in (relatively great) water depth. accounting for erosion of the very thin platform sediments. The sea-level curve resulting from the present work has been Although the flat and undeformed nature of the Russian Platform obtained by two complementary approaches (Sahagian and Holland, suggests relative stability, it does not necessarily preclude the possi- 1991). The first is based on the effect of sea-level changes on depo- bility of changes in low-order residual dynamic topographic support sition, and involves backstripping of sediments to quantify the change of continents relative to oceans (Gurnis, 1991). Estimates of plate- in sea level from one stratigraphic unit to the next. This provides a motion histories (Davis and Solomon, 1981; Gordon and Jurdy, 1986) sea-level curve that is internally consistent and is calibrated and changes in dynamic topography, however, suggest that the Rus- throughout the time represented by preserved sediments, but not sian Platform has not moved significantly with respect to the dynamic beyond. In order to relate the sea-level curve obtained for this time topography (Gurnis, 1991,1992) and that the dynamic topography has interval to present sea level, it is necessary to measure the present not significantly changed since the Jurassic (M. Gurnis, 1993, personal elevation (with respect to present sea level) of various stratigraphic commun.). If, in the future, more refined data and models suggest horizons. This is the second approach which provides a zero on the otherwise, the Russian Platform results will have to be corrected for sea-level elevation scale. this in order to represent the relative volumes of ocean basins and ocean water. STRATIGRAPHIC DATA Eustatic curves which have been compiled in the past (Hallam, 1984, 1991; Haq and others, 1988; Harrison, 1988, 1990) have relied Mesozoic strata are widely distributed on the Russian Platform. on methods of calculating tectonic activity (usually subsidence) in Figure 1 shows some of the wells on the Russian Platform (and ad- order to separate tectonic and eustatic signals reflected in stratigraphic jacent basins) which encounter Mesozoic strata. Preserved strata sequences or paleohypsometric profiles (Greenlee and Moore, 1988). range in age from mid-Jurassic through Upper Cretaceous. In the The errors inherent in these calculations of passive margin tectonic Penza region, they extend into the Paleogene. The younger strata are (thermal) subsidence
Load more

Recommended publications
  • Triassic- Jurassic Stratigraphy Of
    Triassic- Jurassic Stratigraphy of the <JF C7 JL / Culpfeper and B arbour sville Basins, VirginiaC7 and Maryland/ ll.S. PAPER Triassic-Jurassic Stratigraphy of the Culpeper and Barboursville Basins, Virginia and Maryland By K.Y. LEE and AJ. FROELICH U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1472 A clarification of the Triassic--Jurassic stratigraphic sequences, sedimentation, and depositional environments UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1989 DEPARTMENT OF THE INTERIOR MANUEL LUJAN, Jr., Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government Library of Congress Cataloging in Publication Data Lee, K.Y. Triassic-Jurassic stratigraphy of the Culpeper and Barboursville basins, Virginia and Maryland. (U.S. Geological Survey professional paper ; 1472) Bibliography: p. Supt. of Docs. no. : I 19.16:1472 1. Geology, Stratigraphic Triassic. 2. Geology, Stratigraphic Jurassic. 3. Geology Culpeper Basin (Va. and Md.) 4. Geology Virginia Barboursville Basin. I. Froelich, A.J. (Albert Joseph), 1929- II. Title. III. Series. QE676.L44 1989 551.7'62'09755 87-600318 For sale by the Books and Open-File Reports Section, U.S. Geological Survey, Federal Center, Box 25425, Denver, CO 80225 CONTENTS Page Page Abstract.......................................................................................................... 1 Stratigraphy Continued Introduction... ..........................................................................................
    [Show full text]
  • The Geologic Time Scale Is the Eon
    Exploring Geologic Time Poster Illustrated Teacher's Guide #35-1145 Paper #35-1146 Laminated Background Geologic Time Scale Basics The history of the Earth covers a vast expanse of time, so scientists divide it into smaller sections that are associ- ated with particular events that have occurred in the past.The approximate time range of each time span is shown on the poster.The largest time span of the geologic time scale is the eon. It is an indefinitely long period of time that contains at least two eras. Geologic time is divided into two eons.The more ancient eon is called the Precambrian, and the more recent is the Phanerozoic. Each eon is subdivided into smaller spans called eras.The Precambrian eon is divided from most ancient into the Hadean era, Archean era, and Proterozoic era. See Figure 1. Precambrian Eon Proterozoic Era 2500 - 550 million years ago Archaean Era 3800 - 2500 million years ago Hadean Era 4600 - 3800 million years ago Figure 1. Eras of the Precambrian Eon Single-celled and simple multicelled organisms first developed during the Precambrian eon. There are many fos- sils from this time because the sea-dwelling creatures were trapped in sediments and preserved. The Phanerozoic eon is subdivided into three eras – the Paleozoic era, Mesozoic era, and Cenozoic era. An era is often divided into several smaller time spans called periods. For example, the Paleozoic era is divided into the Cambrian, Ordovician, Silurian, Devonian, Carboniferous,and Permian periods. Paleozoic Era Permian Period 300 - 250 million years ago Carboniferous Period 350 - 300 million years ago Devonian Period 400 - 350 million years ago Silurian Period 450 - 400 million years ago Ordovician Period 500 - 450 million years ago Cambrian Period 550 - 500 million years ago Figure 2.
    [Show full text]
  • A Comparison of the Dinosaur Communities from the Middle
    Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 31 July 2018 doi:10.20944/preprints201807.0610.v1 Peer-reviewed version available at Geosciences 2018, 8, 327; doi:10.3390/geosciences8090327 1 Review 2 A comparison of the dinosaur communities from 3 the Middle Jurassic of the Cleveland (Yorkshire) 4 and Hebrides (Skye) basins, based on their ichnites 5 6 Mike Romano 1*, Neil D. L. Clark 2 and Stephen L. Brusatte 3 7 1 Independent Researcher, 14 Green Lane, Dronfield, Sheffield S18 2LZ, England, United Kingdom; 8 [email protected] 9 2 Curator of Palaeontology, The Hunterian, University of Glasgow, University Avenue, Glasgow 10 G12 8QQ, Scotland, United Kingdom; [email protected] 11 3 Chancellor's Fellow in Vertebrate Palaeontology, School of Geosciences, University of Edinburgh, 12 Grant Institute, The King's Buildings, James Hutton Road, Edinburgh EH9 3FE, Scotland, United Kingdom; 13 [email protected] 14 * Correspondence: [email protected]; Tel.: 01246 417330 15 16 Abstract: 17 Despite the Hebrides and Cleveland basins being geographically close, research has not 18 previously been carried out to determine faunal similarities and assess the possibility of links 19 between the dinosaur populations. The palaeogeography of both areas during the Middle Jurassic 20 shows that there were no elevated landmasses being eroded to produce conglomeratic material in 21 the basins at that time. The low-lying landscape and connected shorelines may have provided 22 connectivity between the two dinosaur populations. 23 The dinosaur fauna of the Hebrides and Cleveland basins has been assessed based primarily 24 on the abundant ichnites found in both areas as well as their skeletal remains.
    [Show full text]
  • Uncorking the Bottle: What Triggered the Paleocene/Eocene Thermal Maximum Methane Release? Miriame
    PALEOCEANOGRAPHY, VOL. 16, NO. 6, PAGES 549-562, DECEMBER 2001 Uncorking the bottle: What triggered the Paleocene/Eocene thermal maximum methane release? MiriamE. Katz,• BenjaminS. Cramer,Gregory S. Mountain,2 Samuel Katz, 3 and KennethG. Miller,1,2 Abstract. The Paleocene/Eocenethermal maximum (PETM) was a time of rapid global warming in both marine and continentalrealms that has been attributed to a massivemethane (CH4) releasefrom marine gas hydrate reservoirs. Previously proposedmechanisms for thismethane release rely on a changein deepwatersource region(s) to increasewater temperatures rapidly enoughto trigger the massivethermal dissociationof gas hydratereservoirs beneath the seafloor.To establish constraintson thermaldissociation, we modelheat flow throughthe sedimentcolumn and showthe effectof the temperature changeon the gashydrate stability zone throughtime. In addition,we provideseismic evidence tied to boreholedata for methanerelease along portions of the U.S. continentalslope; the releasesites are proximalto a buriedMesozoic reef front. Our modelresults, release site locations, published isotopic records, and oceancirculation models neither confirm nor refute thermaldissociation as the triggerfor the PETM methanerelease. In the absenceof definitiveevidence to confirmthermal dissociation,we investigatean altemativehypothesis in which continentalslope failure resulted in a catastrophicmethane release.Seismic and isotopic evidence indicates that Antarctic source deepwater circulation and seafloor erosion caused slope retreatalong
    [Show full text]
  • And Early Jurassic Sediments, and Patterns of the Triassic-Jurassic
    and Early Jurassic sediments, and patterns of the Triassic-Jurassic PAUL E. OLSEN AND tetrapod transition HANS-DIETER SUES Introduction parent answer was that the supposed mass extinc- The Late Triassic-Early Jurassic boundary is fre- tions in the tetrapod record were largely an artifact quently cited as one of the thirteen or so episodes of incorrect or questionable biostratigraphic corre- of major extinctions that punctuate Phanerozoic his- lations. On reexamining the problem, we have come tory (Colbert 1958; Newell 1967; Hallam 1981; Raup to realize that the kinds of patterns revealed by look- and Sepkoski 1982, 1984). These times of apparent ing at the change in taxonomic composition through decimation stand out as one class of the great events time also profoundly depend on the taxonomic levels in the history of life. and the sampling intervals examined. We address Renewed interest in the pattern of mass ex- those problems in this chapter. We have now found tinctions through time has stimulated novel and com- that there does indeed appear to be some sort of prehensive attempts to relate these patterns to other extinction event, but it cannot be examined at the terrestrial and extraterrestrial phenomena (see usual coarse levels of resolution. It requires new fine- Chapter 24). The Triassic-Jurassic boundary takes scaled documentation of specific faunal and floral on special significance in this light. First, the faunal transitions. transitions have been cited as even greater in mag- Stratigraphic correlation of geographically dis- nitude than those of the Cretaceous or the Permian junct rocks and assemblages predetermines our per- (Colbert 1958; Hallam 1981; see also Chapter 24).
    [Show full text]
  • Kimmeridgian (Late Jurassic) Cold-Water Idoceratids (Ammonoidea) from Southern Coahuila, Northeastern Mexico, Associated with Boreal Bivalves and Belemnites
    REVISTA MEXICANA DE CIENCIAS GEOLÓGICAS Kimmeridgian cold-water idoceratids associated with Boreal bivalvesv. 32, núm. and 1, 2015, belemnites p. 11-20 Kimmeridgian (Late Jurassic) cold-water idoceratids (Ammonoidea) from southern Coahuila, northeastern Mexico, associated with Boreal bivalves and belemnites Patrick Zell* and Wolfgang Stinnesbeck Institute for Earth Sciences, Heidelberg University, Im Neuenheimer Feld 234, 69120 Heidelberg, Germany. *[email protected] ABSTRACT et al., 2001; Chumakov et al., 2014) was followed by a cool period during the late Oxfordian-early Kimmeridgian (e.g., Jenkyns et al., Here we present two early Kimmeridgian faunal assemblages 2002; Weissert and Erba, 2004) and a long-term gradual warming composed of the ammonite Idoceras (Idoceras pinonense n. sp. and trend towards the Jurassic-Cretaceous boundary (e.g., Abbink et al., I. inflatum Burckhardt, 1906), Boreal belemnites Cylindroteuthis 2001; Lécuyer et al., 2003; Gröcke et al., 2003; Zakharov et al., 2014). cuspidata Sachs and Nalnjaeva, 1964 and Cylindroteuthis ex. gr. Palynological data suggest that the latest Jurassic was also marked by jacutica Sachs and Nalnjaeva, 1964, as well as the Boreal bivalve Buchia significant fluctuations in paleotemperature and climate (e.g., Abbink concentrica (J. de C. Sowerby, 1827). The assemblages were discovered et al., 2001). in inner- to outer shelf sediments of the lower La Casita Formation Upper Jurassic-Lower Cretaceous marine associations contain- at Puerto Piñones, southern Coahuila, and suggest that some taxa of ing both Tethyan and Boreal elements [e.g. ammonites, belemnites Idoceras inhabited cold-water environments. (Cylindroteuthis) and bivalves (Buchia)], were described from numer- ous localities of the Western Cordillera belt from Alaska to California Key words: La Casita Formation, Kimmeridgian, idoceratid ammonites, (e.g., Jeletzky, 1965), while Boreal (Buchia) and even southern high Boreal bivalves, Boreal belemnites.
    [Show full text]
  • Clay Minerals at the Paleocene–Eocene Thermal Maximum: Interpretations, Limits, and Perspectives
    minerals Review Clay Minerals at the Paleocene–Eocene Thermal Maximum: Interpretations, Limits, and Perspectives Fabio Tateo Istituto di Geoscienze e Georisorse, Consiglio Nazionale delle Ricerche (IGG-CNR) Padova, c/o Dipartimento di Geoscienze, Università di Padova, Via Gradenigo 6, I-35131 Padova, Italy; [email protected] Received: 20 October 2020; Accepted: 26 November 2020; Published: 30 November 2020 Abstract: The Paleocene–Eocene Thermal Maximum (PETM) was an “extreme” episode of environmental stress that affected the Earth in the past, and it has numerous affinities concerning the rapid increase in the greenhouse effect. It has left several biological, compositional, and sedimentary facies footprints in sedimentary records. Clay minerals are frequently used to decipher environmental effects because they represent their source areas, essentially in terms of climatic conditions and of transport mechanisms (a more or less fast travel, from the bedrocks to the final site of recovery). Clay mineral variations at the PETM have been studied by several authors in terms of climatic and provenance indicators, but also as tracers of more complicated interplay among different factors requiring integrated interpretation (facies sorting, marine circulation, wind transport, early diagenesis, etc.). Clay minerals were also believed to play a role in the recovery of pre-episode climatic conditions after the PETM exordium, by becoming a sink of atmospheric CO2 that is considered a necessary step to switch off the greenhouse hyperthermal effect. This review aims to consider the use of clay minerals made by different authors to study the effects of the PETM and their possible role as effective (simple) proxy tools for environmental reconstructions.
    [Show full text]
  • Late Jurassic Dinosaurs on the Move, Gastroliths and Long-Distance Migration" (2019)
    Augustana College Augustana Digital Commons Geography: Student Scholarship & Creative Works Geography Winter 12-8-2019 Late Jurassic Dinosaurs on the Move, Gastroliths and Long- Distance Migration Josh Malone Augustana College, Rock Island Illinois Follow this and additional works at: https://digitalcommons.augustana.edu/geogstudent Part of the Geology Commons, Physical and Environmental Geography Commons, Sedimentology Commons, and the Spatial Science Commons Augustana Digital Commons Citation Malone, Josh. "Late Jurassic Dinosaurs on the Move, Gastroliths and Long-Distance Migration" (2019). Geography: Student Scholarship & Creative Works. https://digitalcommons.augustana.edu/geogstudent/8 This Student Paper is brought to you for free and open access by the Geography at Augustana Digital Commons. It has been accepted for inclusion in Geography: Student Scholarship & Creative Works by an authorized administrator of Augustana Digital Commons. For more information, please contact [email protected]. LATE JURASSIC DINOSAURS ON THE MOVE, GASTROLITHS AND LONG- DISTANCE MIGRATION a senior thesis written by Joshua Malone in partial fulfillment of the graduation requirements for the major in Geography Augustana College Rock Island, Illinois 61201 1 Table of Contents 1. Abstract ................................................................................................................................................ 4 2. Introduction ........................................................................................................................................
    [Show full text]
  • A New Middle Jurassic Diplodocoid Suggests an Earlier Dispersal and Diversification of Sauropod Dinosaurs
    ARTICLE DOI: 10.1038/s41467-018-05128-1 OPEN A new Middle Jurassic diplodocoid suggests an earlier dispersal and diversification of sauropod dinosaurs Xing Xu1, Paul Upchurch2, Philip D. Mannion 3, Paul M. Barrett 4, Omar R. Regalado-Fernandez 2, Jinyou Mo5, Jinfu Ma6 & Hongan Liu7 1234567890():,; The fragmentation of the supercontinent Pangaea has been suggested to have had a profound impact on Mesozoic terrestrial vertebrate distributions. One current paradigm is that geo- graphic isolation produced an endemic biota in East Asia during the Jurassic, while simul- taneously preventing diplodocoid sauropod dinosaurs and several other tetrapod groups from reaching this region. Here we report the discovery of the earliest diplodocoid, and the first from East Asia, to our knowledge, based on fossil material comprising multiple individuals and most parts of the skeleton of an early Middle Jurassic dicraeosaurid. The new discovery challenges conventional biogeographical ideas, and suggests that dispersal into East Asia occurred much earlier than expected. Moreover, the age of this new taxon indicates that many advanced sauropod lineages originated at least 15 million years earlier than previously realised, achieving a global distribution while Pangaea was still a coherent landmass. 1 Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology & Paleoanthropology, Chinese Academy of Sciences, 100044 Beijing, China. 2 Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK. 3 Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK. 4 Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK. 5 Natural History Museum of Guangxi, 530012 Nanning, Guangxi, China.
    [Show full text]
  • The First Record of Freshwater Plesiosaurian from the Middle
    Gao et al. Journal of Palaeogeography (2019) 8:27 https://doi.org/10.1186/s42501-019-0043-5 Journal of Palaeogeography ORIGINALARTICLE Open Access The first record of freshwater plesiosaurian from the Middle Jurassic of Gansu, NW China, with its implications to the local palaeobiogeography Ting Gao, Da-Qing Li* , Long-Feng Li and Jing-Tao Yang Abstract Plesiosaurs are one of the common groups of aquatic reptiles in the Mesozoic, which mainly lived in marine environments. Freshwater plesiosaurs are rare in the world, especially from the Jurassic. The present paper reports the first freshwater plesiosaur, represented by four isolated teeth from the Middle Jurassic fluviolacustrine strata of Qingtujing area, Jinchang City, Gansu Province, Northwest China. These teeth are considered to come from one individual. The comparative analysis of the corresponding relationship between the body and tooth sizes of the known freshwater plesiosaur shows that Jinchang teeth represent a small-sized plesiosaurian. Based on the adaptive radiation of plesiosaurs and the palaeobiogeographical context, we propose a scenario of a river leading to the Meso-Tethys in the Late Middle Jurassic in Jinchang area, which may have provided a channel for the seasonal migration of plesiosaurs. Keywords: Freshwater plesiosaur, Middle Jurassic, Jinchang, Gansu Province, Palaeobiogeography 1 Introduction Warren 1980;Satoetal.2003; Kear 2012). Up to now, Plesiosaurs are one of the most familiar groups of Mesozoic the taxonomic affinities of most freshwater plesio- marine reptiles, which mainly lived in marine environ- saurs have remained unclear; some of them are re- ments. The records of plesiosaurs in non-marine deposits ferred to Plesiosauroidea (Cruickshank and Fordyce are sparse in comparison to those from marine sediments.
    [Show full text]
  • The Palaeocene – Eocene Thermal Maximum Super Greenhouse
    The Palaeocene–Eocene Thermal Maximum super greenhouse: biotic and geochemical signatures, age models and mechanisms of global change A. SLUIJS1, G. J. BOWEN2, H. BRINKHUIS1, L. J. LOURENS3 & E. THOMAS4 1Palaeoecology, Institute of Environmental Biology, Utrecht University, Laboratory of Palaeobotany and Palynology, Budapestlaan 4, 3584 CD Utrecht, The Netherlands (e-mail: [email protected]) 2Earth and Atmospheric Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907, USA 3Faculty of Geosciences, Department of Earth Sciences, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, The Netherlands 4Center for the Study of Global Change, Department of Geology and Geophysics, Yale University, New Haven CT 06520-8109, USA; also at Department of Earth & Environmental Sciences, Wesleyan University, Middletown, CT, USA Abstract: The Palaeocene–Eocene Thermal Maximum (PETM), a geologically brief episode of global warming associated with the Palaeocene–Eocene boundary, has been studied extensively since its discovery in 1991. The PETM is characterized by a globally quasi-uniform 5–8 8C warming and large changes in ocean chemistry and biotic response. The warming is associated with a negative carbon isotope excursion (CIE), reflecting geologically rapid input of large amounts of isotopically light CO2 and/or CH4 into the exogenic (ocean–atmosphere) carbon pool. The biotic response on land and in the oceans was heterogeneous in nature and severity, including radiations, extinctions and migrations. Recently, several events that appear
    [Show full text]
  • Paleogeographic Maps Earth History
    History of the Earth Age AGE Eon Era Period Period Epoch Stage Paleogeographic Maps Earth History (Ma) Era (Ma) Holocene Neogene Quaternary* Pleistocene Calabrian/Gelasian Piacenzian 2.6 Cenozoic Pliocene Zanclean Paleogene Messinian 5.3 L Tortonian 100 Cretaceous Serravallian Miocene M Langhian E Burdigalian Jurassic Neogene Aquitanian 200 23 L Chattian Triassic Oligocene E Rupelian Permian 34 Early Neogene 300 L Priabonian Bartonian Carboniferous Cenozoic M Eocene Lutetian 400 Phanerozoic Devonian E Ypresian Silurian Paleogene L Thanetian 56 PaleozoicOrdovician Mesozoic Paleocene M Selandian 500 E Danian Cambrian 66 Maastrichtian Ediacaran 600 Campanian Late Santonian 700 Coniacian Turonian Cenomanian Late Cretaceous 100 800 Cryogenian Albian 900 Neoproterozoic Tonian Cretaceous Aptian Early 1000 Barremian Hauterivian Valanginian 1100 Stenian Berriasian 146 Tithonian Early Cretaceous 1200 Late Kimmeridgian Oxfordian 161 Callovian Mesozoic 1300 Ectasian Bathonian Middle Bajocian Aalenian 176 1400 Toarcian Jurassic Mesoproterozoic Early Pliensbachian 1500 Sinemurian Hettangian Calymmian 200 Rhaetian 1600 Proterozoic Norian Late 1700 Statherian Carnian 228 1800 Ladinian Late Triassic Triassic Middle Anisian 1900 245 Olenekian Orosirian Early Induan Changhsingian 251 2000 Lopingian Wuchiapingian 260 Capitanian Guadalupian Wordian/Roadian 2100 271 Kungurian Paleoproterozoic Rhyacian Artinskian 2200 Permian Cisuralian Sakmarian Middle Permian 2300 Asselian 299 Late Gzhelian Kasimovian 2400 Siderian Middle Moscovian Penn- sylvanian Early Bashkirian
    [Show full text]