DOCSLIB.ORG

Simulating the Evolution of the Asian and African Monsoons During The

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Simulating the Evolution of the Asian and African Monsoons During The Simulating the evolution of the Asian and African monsoons during the past 30 Myr using an atmospheric general circulation model Frédéric Fluteau, Gilles Ramstein, Jean Besse To cite this version: Frédéric Fluteau, Gilles Ramstein, Jean Besse. Simulating the evolution of the Asian and African monsoons during the past 30 Myr using an atmospheric general circulation model. Journal of Geo- physical Research: Atmospheres, American Geophysical Union, 1999, 104 (D10), pp.11995-12018. 10.1029/1999JD900048. hal-03012020 HAL Id: hal-03012020 https://hal.archives-ouvertes.fr/hal-03012020 Submitted on 7 Dec 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 104, NO. D10, PAGES 11,995-12,018, MAY 27, 1999 Simulating the evolution of the Asian and African monsoons during the past 30 Myr using an atmospheric general circulation model Fr6d6ricFluteau, 1'2 G. Ramstein2 and Jean Besse 1 Abstract. At geologictimescales, many proxy data suggest a contrastingevolution of Asianand African monsoonssince the Oligocene.The Asian summermonsoon increases drastically around 8 Ma, whereasthe African summermonsoon gradually weakens during the Miocene.Using an atmosphericgeneral circulation model, we simulatemost of the spatialevolutions of both monsoonsonly accountingfor the changesof paleogeography,including continental drift, orogeny, and sealevel change.The paleogeographicchanges modify drastically the climateover central and southernAsia betweenthe Oligoceneand the present.The retreatof an epicontinentalsea warms centralEurasia in summer.The heatingof thisarea and the uplifts of the Tibetanplateau and of the Himalayasdeepen the Asianlow-pressure cell anddisplace it northwest.This thenshifts precipitationfrom Indochinatoward the southernflank of the Himalayas.This is in good agreementwith proxydata. Therefore our modelingstudies support a shiftand a strengtheningof the Asianmonsoon during the late Tertiary ratherthan a real "onset".We suggestthat the increase in seasonalprecipitation and the strengtheningof the numberof dayswith heavyrainfall over the Himalayasfrom 30 Ma to the presentmay be of criticalimportance to explainthe long- term evolutionof physicalerosion of this area.We alsoinvestigate the respectiveimpact of the Paratethysshrinkage and of the Tibetanplateau uplift throughsensitivity experiments and prove that the Paratethysretreat plays an importantrole in monsoonevolution. The northwarddrift of the African continentconfines summer monsoon precipitation to a thinbelt whichfavors the stretching of the subtropicaldesert, in goodagreement with data.We finally showthat duringthe Oligocene, the African andAsian monsoon systems are clearlyseparated by the Tethysseaway. The closureof this seawayand the evolutionof the Asianmonsoon induce a connectionbetween both monsoon systemsin the low andmiddle troposphere. 1. Introduction Although driven by a commonmechanism, the rainfall intensity of the Asian monsoon is stronger than that of the African The monsoondominates the large-scaletropical circulationon monsoon. This difference is due to the Asian continental size and both the African and Southeast Asian continents. It results from to the presenceof orography(Tibetan plateau and Himalayan the thermal contrastbetween the continent and the surrounding range) [James,1994]. ocean [Hastenrath, 1985; Webster, 1987]. In winter, the Monsoonspresent a large time variability, rangingfrom years continent is colder than the ocean and induces northeasterly to thousandsof yearsand more [Prell et al., 1992]. At geologic winds toward the Arabian Sea (Asian monsoon)and toward the timescales(more than a million years), paleoclimaticindicators Gulf of Guinea(African monsoon), producing weak precipitation suggestan abruptstrengthening of the Asianmonsoon during the because of the little moisture brought by these atmospheric late Miocene, about7.5 Ma [Quade et al., 1989; Prell et al., masses [Hastenrath, 1985]. In summer, overheated continents 1992]. Althoughsparse, paleoclimatic indicators suggest the become warmer than the ocean. A low-pressurecell is then developmentof a subtropicaldesert over northemAfrica to the generatedover the warm continents,and a high-pressurecell over detrimentof the monsoon[Axelrod and Raven, 1978;Ruddiman the cold ocean. This differential heating induces advectionof et al., 1989; Maley, 1996]. moist air, producing heavy precipitation in a tropical belt At geologictimescales, monsoon evolution may be influenced stretchingacross Africa, India, and SoutheastAsia. The release by differentforcing factors such as paleogeographicchanges, of a huge amountof latent heat contributesto the strengthening oceanic circulation changes, variations of carbon dioxide of the monsoon circulation [Hastenrath, 1985; Webster, 1987]. concentration and variations in insolation [Barron and Washington,1984; Frakes et al., 1992]. The impactof someof these forcing factors was investigatedthrough numerical 1Laboratoirede Pa16omagn6tisme et G6odynamique, Institut de experimentsusing an atmosphericgeneral circulation model Physiquedu Globede Paris. (AGCM) [Barronand Washington,1984; Kutzbach et al., 1989; 2LaboratoiredesSciences duClimat etde l'Environnement, CE-Saclay. Ramstein et al., 1997a]. Until now, mostexperiments on the monsoonhave focusedon Copyright1999 by theAmerican Geophysical Union. theimpact of a mountainuplift without accounting for changesin Papernumber 1999JD900048. platemotions or sea-landdistribution. Sensitivity experiments to 0148-0227/99/1999JD900048509.00 the Himalayanand Tibetanuplift were doneusing full or half 11,995 11,996 FLUTEAU ET AL.: SIMULATING THE EVOLUTION OF MONSOONS altitude of the mountain rangesin a presentday environment in their relative positions. For this, we use the finite [Kutzbach et al., 1989; Ruddirnanand Kutzbach, 1989; Prell and reconstructionparameters of Olivet et al. [ 1984] for the North Kutzback, 1992; Kutzbach et al., 1993]. Major resultswere that and Central Atlantic Ocean, of Niirnberg and Muller [ 1991] for the uplift of the Tibetanplateau significantly increases the Asian the South Atlantic Ocean, and of Royer and Sandwell [ 1989] for monsoonintensity over mostof southernAsia (+50% in summer the Indian Ocean. The paleomagneticsynthetic apparent polar precipitation) [Prell and Kutzbach, 1992] and modifies the wanderpaths (APWPs) of Besseand Courtillot [ 1991] were then climate over adjacentareas (Siberia, central Asia, Middle East, used to fix the paleolatitude grid. These APWPs were Mediterranean basin) [Kutzbach et al., 1989; Ruddirnan and constructedfrom a careful selectionof the best paleomagnetic Kutzbach, 1989]. polesavailable for Asia, Europe,America, and Africa, transferred Other factors such as atmospheric carbon dioxide onto a single referenceframe and averagedover 20 Myr time concentration, oceanic circulation, and orbital parameters windows. In each of these independentwindows, data from influence the climate. The atmosphericcarbon dioxide plays a individual plates are almost always found to be in agreement, significantrole. The modelingcurve of Berner [ 1992] points out whichverifies the qualityof the originalpaleomagnetic data, the an atmosphericCO 2 concentrationdoubled with respect to the cinematicmodels, and the axial dipole assumption.The 20 Ma present day in the past 30 Myr. Prell and Kutzbach [1992] sequencesof paleomagneticpoles define a "synthetic"APWP, in showedthat a CO2 doublingenhances monsoon precipitation by excellent agreementwith the "classical"paths from each plate. only 7%. Conversely,this CO 2 doublingcould lead to a 6øC The 95% level uncertaintieson pole positionsare of the orderof warmingat middle and high latitudes[Ruddirnan et al., 1997a]. 3ø for the 10 and 30 Ma poles,leading to rather well constrained Oceaniccirculation patterns are induced by the evolution of paleolatitudes. oceanic basinsand the closureor opening of seaways(another The hot-spot referenceframe [Morgan, 1983] was not used consequenceof plate motions).Despite tectonic drift, the major becausesignificant inter-hot spot motion [Chase, 1983; Molnar features of the oceanic circulation in the late Cenozoic were and Stock, 1987] and true polar wander [Besseand Courtillot, relatively similar to present day circulation. A thermohaline 1991] cast some doubt on the use of this method as a global oceanic circulation began to be establishedduring the early reconstruction tool. Miocene [Kennett and Scott, 1990]. Oxygen isotopic analyses The proceduredescribed above can be used as long as show a weak cooling of sea surfacetemperature (SST) at high continentsare not stronglydeformed, or separatedby destructive latitudesduring the late Tertiary but hardly any changesin SST active margins. This is, of course,not the case for the regions occurred in the tropics [Frakes et al., 1994]. Finally, using an borderingthe Tethys, where a collision has occurredsince the AGCM coupledwith a mixed oceaniclayer allowing to take into end of the Mesozoic.In particular,central and southeastAsia are account
Load more

Recommended publications
  • Fresh- and Brackish-Water Cold-Tolerant Species of Southern Europe: Migrants from the Paratethys That Colonized the Arctic
    water Review Fresh- and Brackish-Water Cold-Tolerant Species of Southern Europe: Migrants from the Paratethys That Colonized the Arctic Valentina S. Artamonova 1, Ivan N. Bolotov 2,3,4, Maxim V. Vinarski 4 and Alexander A. Makhrov 1,4,* 1 A. N. Severtzov Institute of Ecology and Evolution, Russian Academy of Sciences, 119071 Moscow, Russia; [email protected] 2 Laboratory of Molecular Ecology and Phylogenetics, Northern Arctic Federal University, 163002 Arkhangelsk, Russia; [email protected] 3 Federal Center for Integrated Arctic Research, Russian Academy of Sciences, 163000 Arkhangelsk, Russia 4 Laboratory of Macroecology & Biogeography of Invertebrates, Saint Petersburg State University, 199034 Saint Petersburg, Russia; [email protected] * Correspondence: [email protected] Abstract: Analysis of zoogeographic, paleogeographic, and molecular data has shown that the ancestors of many fresh- and brackish-water cold-tolerant hydrobionts of the Mediterranean region and the Danube River basin likely originated in East Asia or Central Asia. The fish genera Gasterosteus, Hucho, Oxynoemacheilus, Salmo, and Schizothorax are examples of these groups among vertebrates, and the genera Magnibursatus (Trematoda), Margaritifera, Potomida, Microcondylaea, Leguminaia, Unio (Mollusca), and Phagocata (Planaria), among invertebrates. There is reason to believe that their ancestors spread to Europe through the Paratethys (or the proto-Paratethys basin that preceded it), where intense speciation took place and new genera of aquatic organisms arose. Some of the forms that originated in the Paratethys colonized the Mediterranean, and overwhelming data indicate that Citation: Artamonova, V.S.; Bolotov, representatives of the genera Salmo, Caspiomyzon, and Ecrobia migrated during the Miocene from I.N.; Vinarski, M.V.; Makhrov, A.A.
    [Show full text]
  • Paleoenvironmental Reconstruction of the Early to Middle Miocene Central Paratethys Using Stable Isotopes from Bryozoan Skeletons
    Paleoenvironmental reconstruction of the Early to Middle Miocene Central Paratethys using stable isotopes from bryozoan skeletons Marcus M. Key, Kamil Zágoršek & William P. Patterson International Journal of Earth Sciences GR Geologische Rundschau ISSN 1437-3254 Int J Earth Sci (Geol Rundsch) DOI 10.1007/s00531-012-0786-z 1 23 Your article is protected by copyright and all rights are held exclusively by Springer- Verlag. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your work, please use the accepted author’s version for posting to your own website or your institution’s repository. You may further deposit the accepted author’s version on a funder’s repository at a funder’s request, provided it is not made publicly available until 12 months after publication. 1 23 Author's personal copy Int J Earth Sci (Geol Rundsch) DOI 10.1007/s00531-012-0786-z ORIGINAL PAPER Paleoenvironmental reconstruction of the Early to Middle Miocene Central Paratethys using stable isotopes from bryozoan skeletons Marcus M. Key Jr. • Kamil Za´gorsˇek • William P. Patterson Received: 26 September 2011 / Accepted: 21 April 2012 Ó Springer-Verlag 2012 Abstract Stable carbon and oxygen isotope values from Introduction single bryozoan colonies were used to reconstruct the paleoenvironments of the Early to Middle Miocene (Ottnangian The use of d13C and d18O values for paleoenvironmental to Badenian) sediments of the Central Paratethys. This approach interpretation of the Central Paratethys in the Miocene has utilizes a locally abundant allochem while avoiding matrix only been applied to a few select allochem types including and multiple allochem contamination from bulk rock foraminifera (Durakiewicz et al.
    [Show full text]
  • Provenance and Palaeogeographic Evolution of Lower Miocene Sediments in the Eastern North Alpine Foreland Basin
    Swiss Journal of Geosciences (2019) 112:269–286 https://doi.org/10.1007/s00015-018-0312-9 (0123456789().,-volV)(0123456789().,-volV) Provenance and palaeogeographic evolution of Lower Miocene sediments in the eastern North Alpine Foreland Basin 1 1 1 1 Wolfgang Knierzinger • Michael Wagreich • Markus Palzer-Khomenko • Susanne Gier • 1 2 1 3 Maria Meszar • Eun Young Lee • Veronika Koukal • Philipp Strauss Received: 19 January 2018 / Accepted: 30 May 2018 / Published online: 4 July 2018 Ó Swiss Geological Society 2018 Abstract Detrital heavy mineral analysis and sediment chemistry of Lower Miocene sediments of the Lower Austrian Northern Alpine Foreland Basin generally indicate provenance from metapelitic source rocks. The sediments of the Traisen For- mation (Ottnangian) were primarily derived from Alpine sources such as the Austroalpine crystalline units of the Eastern Alps and reworked and eroded siliciclastics strata on top of the Northern Calcareous Alps and, in addition, low-grade metamorphic rocks of the Bohemian Massif. Ottnangian and Karpatian sediments in the subground of the northern Lower Austrian Molasse basin were mainly fed from the same southern sources, from low-grade metamorphic rocks of the Bohemian Massif and via resedimentation of Lower Miocene and Palaeogene of the Waschberg–Zˇ da´nice Unit and the Vienna Basin. A large-scale input of material from the Rhenodanubian Flysch Zone and of higher-grade metamorphic units and granites of the Bohemian Massif in the Lower Miocene Molasse basin can be ruled out. A compilation of well sections and heavy mineral data point to the existence of a partly emerged, N–S oriented ridge during the Egerian.
    [Show full text]
  • The Oligo–Miocene Closure of the Tethys Ocean and Evolution of the Proto‑Mediterranean Sea Adi Torfstein1,2* & Josh Steinberg3
    www.nature.com/scientificreports OPEN The Oligo–Miocene closure of the Tethys Ocean and evolution of the proto‑Mediterranean Sea Adi Torfstein1,2* & Josh Steinberg3 The tectonically driven Cenozoic closure of the Tethys Ocean invoked a signifcant reorganization of oceanic circulation and climate patterns on a global scale. This process culminated between the Mid Oligocene and Late Miocene, although its exact timing has remained so far elusive, as does the subsequent evolution of the proto-Mediterranean, primarily due to a lack of reliable, continuous deep-sea records. Here, we present for the frst time the framework of the Oligo–Miocene evolution of the deep Levant Basin, based on the chrono-, chemo- and bio- stratigraphy of two deep boreholes from the Eastern Mediterranean. The results reveal a major pulse in terrigeneous mass accumulation rates (MARs) during 24–21 Ma, refecting the erosional products of the Red Sea rifting and subsequent uplift that drove the collision between the Arabian and Eurasian plates and the efective closure of the Indian Ocean-Mediterranean Seaway. Subsequently, the proto-Mediterranean experienced an increase in primary productivity that peaked during the Mid‑Miocene Climate Optimum. A region‑ wide hiatus across the Serravallian (13.8–11.6 Ma) and a crash in carbonate MARs during the lower Tortonian refect a dissolution episode that potentially marks the earliest onset of the global middle to late Miocene carbonate crash. Global climate oscillations during the Miocene refect major events in the Earth’s history such as the closure of the Indian Ocean-Mediterranean Seaway (IOMS), Mid-Miocene Climate Optimum (MMCO), and the glacia- tion of Antarctica1.
    [Show full text]
  • Late Middle Miocene) Marine Fishes and Mammals As Proxies for the Onset of the Eastern Paratethys Re-Colonisation by Vertebrate Fauna
    Palaeontologia Electronica palaeo-electronica.org The Volhynian (late Middle Miocene) marine fishes and mammals as proxies for the onset of the Eastern Paratethys re-colonisation by vertebrate fauna Pavel Gol’din, Bogdan Stelian Haiduc, Oleksandr Kovalchuk, Marcin Górka, Pavlo Otryazhyi, Mihai Brânzilă, Elena Ionela Păun, Zoltán Barkaszi, Paul Ţibuleac, and Bogdan Gabriel Răţoi ABSTRACT The late Middle Miocene of South-Eastern Europe was the time of major basin- wide physical and biogeographical transformations of marine environments with mass extinction and faunal replacement. We examined new material comprising marine fishes and mammals, re-examined earlier finds, and analysed previously published data on the marine vertebrate assemblage that lived along the western and northern edges of the Eastern Paratethys. The studied materials represent marine fishes that belong to at least four families (Clupeidae, Sparidae, Bothidae, and Scombridae), including Sarmatella doljeana, Sparus brusinai, Bothus parvulus, and indeterminate scombroids; true seals (Phocinae), the earliest seal record in the area; small toothed whales of the family Kentriodontidae, including Kentriodon fuchsii, whose presence in the Volhynian is confirmed here, and two other dwarf forms; a bizarre toothed whale Pachyacanthus, the first record in the area between the Vienna Basin and Central Asia; baleen whales, including an indeterminate member of the family Cetotheriidae, and “Archaeocetus fockii”. The material found so far hints to a low taxonomic diversity and biogeographical connections to both the synchronous Sarmatian fauna of the Cen- tral Paratethys and the later Bessarabian Eastern Paratethyan fauna. The taxonomic composition of the faunal assemblage and its biogeographical connections indicate that it has Central Paratethyan origin and shows an overall west to east direction of gradual dispersal, from the Central Paratethys through the Fore-Carpathian Basin and further east.
    [Show full text]
  • A New Species of the Enigmatic Shark Genus Nanocetorhinus (Chondrichthyes) from the Oligocene of Austria with Palaeoceanographic Implications
    Austrian Journal of Earth Sciences Vienna 2020 Volume 113/2 229 - 236 DOI: 10.17738/ajes.2020.0014 A new species of the enigmatic shark genus Nanocetorhinus (Chondrichthyes) from the Oligocene of Austria with palaeoceanographic implications Iris FEICHTINGERa*, Jürgen POLLERSPÖCKb and Mathias HARZHAUSERa a Geological-Palaeontological Department, Natural History Museum, Burgring 7, 1010 Vienna, Austria b Bavarian State Collection of Zoology, Münchhausenstraße 21, 81247 Munich, Germany; [email protected] *) Corresponding author: [email protected] KEYWORDS Paratethys, Egerian, Elasmobranchii, planktivorous, dermal denticle Abstract Deep-neritic sediments of the Eferding Formation (Egerian, Upper Oligocene) of Upper Austria from the Kamig kaolinite quarry revealed minute teeth of the putatively planktivorous shark genus Nanocetorhinus. This is the oldest unambiguous record of this rarely documented genus, which was known so far only from Miocene deposits of Europe, North America and Japan. Based on previous studies, which showed a positive correlation between sediments of nutrient rich waters and plankton blooms with a majority of ichthyoliths of Keasius and Nanocetorhinus, we argue for a filter-feeding and migratory lifestyle of the latter. Thus, it is supposed that Nanocetorhinus migrated seasonally for foraging, in a similar way to the extant basking shark Cetorhinus maximus. This mode of life and the wide paleogeographic distribution of the open marine genus Nanocetorhinus requires a deep and fully marine connection between the Paratethys and the Proto-Mediterranean Sea during late Oligocene times, which might have been established via the Slovenian Corridor. 1. Introduction more protected eastern margin (Harzhauser and Man- Ichthyoliths of exclusively marine vertebrates are a heri- dic, 2002).
    [Show full text]
  • The Alpine-Carpathian-Dinaridic Orogenic System: Correlation and Evolution of Tectonic Units
    1661-8726/08/010139–45 Swiss J. Geosci. 101 (2008) 139–183 DOI 10.1007/s00015-008-1247-3 Birkhäuser Verlag, Basel, 2008 The Alpine-Carpathian-Dinaridic orogenic system: correlation and evolution of tectonic units STEFAN M. SCHMID 1, DANIEL BERNOULLI 1, BERNHARD FÜGENSCHUH 2, LIVIU MATENCO 3, SENECIO SCHEFER 1, RALF SCHUSTER 4, MATTHIAS TISCHLER 1 & KAMIL USTASZEWSKI 1 Key words: tectonics, collisional Orogens, Ophiolites, alps, Carpathians, Dinarides ABSTRACT A correlation of tectonic units of the Alpine-Carpathian-Dinaridic system of geometries resulting from out-of-sequence thrusting during Cretaceous and orogens, including the substrate of the Pannonian and Transylvanian basins, is Cenozoic orogenic phases underlay a variety of multi-ocean hypotheses, that presented in the form of a map. Combined with a series of crustal-scale cross were advanced in the literature and that we regard as incompatible with the sections this correlation of tectonic units yields a clearer picture of the three- field evidence. dimensional architecture of this system of orogens that owes its considerable The present-day configuration of tectonic units suggests that a former complexity to multiple overprinting of earlier by younger deformations. connection between ophiolitic units in West Carpathians and Dinarides was The synthesis advanced here indicates that none of the branches of the disrupted by substantial Miocene-age dislocations along the Mid-Hungarian Alpine Tethys and Neotethys extended eastward into the Dobrogea Orogen. Fault Zone, hiding a former lateral change in subduction polarity between Instead, the main branch of the Alpine Tethys linked up with the Meliata- West Carpathians and Dinarides. The SW-facing Dinaridic Orogen, mainly Maliac-Vardar branch of the Neotethys into the area of the present-day In- structured in Cretaceous and Palaeogene times, was juxtaposed with the Tisza ner Dinarides.
    [Show full text]
  • Towards Better Correlation of the Central Paratethys Regional Time Scale with the Standard Geological Time Scale Of­ the Miocene Epoch
    GEOLOGICA CARPATHICA, JUNE 2018, 69, 3, 283–300 doi: 10.1515/geoca-2018-0017 Towards better correlation of the Central Paratethys regional time scale with the standard geological time scale of the Miocene Epoch MICHAL KOVÁČ1, , EVA HALÁSOVÁ1, NATÁLIA HUDÁČKOVÁ1, KATARÍNA HOLCOVÁ2, MATÚŠ HYŽNÝ1, MICHAL JAMRICH1 and ANDREJ RUMAN1 1 Department of Geology and Palaeontology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 842 15 Bratislava, Slovakia; [email protected], [email protected], [email protected], [email protected], [email protected], [email protected] 2 Institute of Geology and Palaeontology, Faculty of Sciences, Charles University, Albertov 6, 128 43 Praha 2, Czech Republic; [email protected] (Manuscript received November 23, 2017; accepted in revised form March 15, 2018) Abstract: Depositional sequences originating in semi-enclosed basins with endemic biota, partly or completely isolated from the open ocean, frequently do not allow biostratigraphic correlations with the standard geological time scale (GTS). The Miocene stages of the Central Paratethys represent regional chronostratigraphic units that were defined in type sections mostly on the basis of biostratigraphic criteria. The lack of accurate dating makes correlation within and between basins of this area and at global scales difficult. Although new geochronological estimates increasingly constrain the age of stage boundaries in the Paratethys, such estimates can be misleading if they do not account for diachronous boundaries between lithostratigraphic formations and for forward smearing of first appearances of index species (Signor-Lipps effect), and if they are extrapolated to whole basins. Here, we argue that (1) geochronological estimates of stage boundaries need to be based on sections with high completeness and high sediment accumulation rates, and (2) that the boundaries should preferentially correspond to conditions with sufficient marine connectivity between the Paratethys and the open ocean.
    [Show full text]
  • Triassic and Cenozoic Palaeobiogeography: Two Case Studies in Quantitative Modelling Using Idl®
    Palaeontologia Electronica http://palaeo-electronica.org TRIASSIC AND CENOZOIC PALAEOBIOGEOGRAPHY: TWO CASE STUDIES IN QUANTITATIVE MODELLING USING IDL® Arnaud Brayard, Marie-Anne Héran, Loïc Costeur, and Gilles Escarguel ABSTRACT This work presents two examples of palaeobiogeographic reconstruction using the Interactive Data Language® (IDL). Although this meta-language is devoted to geo- scientists and offers an array of easily usable tools, few palaeontologists actually use it. Our purpose is to illustrate how the IDL can be used to generate clear and direct visu- alizations of simulation results and interpolation methods for personal Geographic Information Systems (GIS). The first example is a paleogeographic simulation of the biodiversity evolution of planktonic species (and especially ammonoids) in the Early Triassic. Principal results of this global scale simulation are that the formation of a marine latitudinal gradient of species richness depends on the shape and magnitude of the Sea Surface Tempera- ture (SST) gradient, and the geographic location of the group’s ancestor. Thus, the recovery pattern of Early Triassic ammonoids species richness can be simulated and explained by a general increasing trend in steepness of the SST gradient. The second example describes a custom-designed GIS for large European Neo- gene continental mammals. Species richness and ecomorphologic parameters are interpolated, monitored in several ways, and discussed. Comparisons with the present- day distribution of large European mammals are also drawn and allow us to recognize that a broad North/South aridity gradient already existed by the Late Miocene with more open environments in Southern Europe. Arnaud Brayard. Paläontologisches Institut und Museum der Universität Zürich, Karl-Schmid Strasse 4, CH-8006 Zürich, Switzerland and UMR-5125 CNRS, Paléoenvironnements et Paléobiosphère, Université Claude Bernard Lyon 1, 2 rue Dubois, F-69622 Villeurbanne Cedex, France [email protected] Marie-Anne Héran.
    [Show full text]
  • The Correlation of the Neogene of Central and Eastern Paratethys Segments of Ukraine with the International Stratigraphic Chart Based on Planktonic Microfossils
    GEOLOGICA CARPATHICA, JUNE 2015, 66, 3, 235—244 doi: 10.1515/geoca-2015-0022 The correlation of the Neogene of Central and Eastern Paratethys segments of Ukraine with the International Stratigraphic Chart based on planktonic microfossils PETRO GOZHYK, VLADIMIR SEMENENKO†, AIDA ANDREEVA-GRIGOROVICH and NINEL MASLUN Institute of Geological Sciences, National Academy of Sciences of Ukraine, O. Gonchara str. 55-b, 01601 Kiev-54, Ukraine; [email protected]; [email protected] (Manuscript received May 20, 2014; accepted in revised form March 12, 2015) Abstract: Detailed analysis of microplankton occurrence (planktonic foraminifera, nannoplankton, dinocysts) in Neo- gene sediments situated at the north-western and south-eastern margins of Ukraine enabled us to distinguish 10 associa- tions of oceanic plankton which specified the relative age of lithostratigraphic units of various regions and were used as correlation levels within the Central and Eastern Paratethys strata. Moreover, an attempt to correlate regional stages and the International Stratigraphic Chart (ISC) is performed. The Oligocene/Miocene boundary (of ISC) represented by the correlation level I was placed within the Central Paratethys regional stage Egerian and in the middle part of the Eastern Paratethys regional stage Caucasian s.l. The latter regional stage is subdivided by the correlation level into two sub- stages: Lower Caucasian (Chattian of ISC) and Upper Caucasian (Aquitanian of ISC). The correlation level II was placed within the upper part of the Eggenburgian and lower part of the Batisifonian (Sakaraulian) regional stages and is correlated approximately with the middle part of the Burdigalian (of ISC). The base of the Middle Miocene is marked by level IV and was recognized only in deposits of the Eastern Paratethys belonging to the Tarkhanian regional stage.
    [Show full text]
  • 55. History of the Mediterranean Salinity Crisis
    55. HISTORY OF THE MEDITERRANEAN SALINITY CRISIS Kenneth J. Hsü,1 Lucien Montadert,2 Daniel Bernoulli,3 Maria Bianca Cita,4 Albert Erickson,5 Robert E. Garrison,6 Robert B. Kidd,7 Frederic Mélières,8 Carla Müller,9 and Ramil Wright10 ABSTRACT An equatorial ocean existed during the Mesozoic between Africa and Eurasia known as Tethys. The Alpine Orogeny, culminating in the late Eocene and Oligocene, eliminated much of this ancient ocean. However, the relic Tethys, combined with the newly created post-orogenic basins, still retained host to a Mediterranean seaway. The link was first broken in the Burdigalian with the collision of Africa and Eurasia along the Middle East front. This event started the gradual changes towards a cooler and drier climate in regions which were now situated on the west side of a continent. Middle Miocene movements cut off forever the opening on the east to the Indo-Pacific. Also the Perialpine Depression north of the Alps was raised and the communication between the Mediterra- nean and the Paratethys was severed. The considerable fresh-water supply from Central Europe was then diverted to the Paratethys, and the reorganization of drainages placed considerable strain on the water budget of the Mediterranean. Finally, soon after the beginning of the Messinian stage, the last opening to the Atlantic, the Betic and Rif straits were closed. Evaporative drawdown of the isolated Mediterranean sea level, leading to desiccation, became unavoidable, since evaporative loss considerably exceeded precipi- tation and influx from rivers. The Mediterranean Evaporite can be divided into two units. The deep-sea drilling did not penetrate the Main Salt or the lower unit.
    [Show full text]
  • Paratethys Pacing of the Messinian Salinity Crisis: Low Salinity Waters Contributing to Gypsum Precipitation?
    Earth and Planetary Science Letters 532 (2020) 116029 Contents lists available at ScienceDirect Earth and Planetary Science Letters www.elsevier.com/locate/epsl Paratethys pacing of the Messinian Salinity Crisis: Low salinity waters contributing to gypsum precipitation? Arjen Grothe a, Federico Andreetto a, Gert-Jan Reichart a,b, Mariette Wolthers a, Christiaan G.C. Van Baak a,c, Iuliana Vasiliev d, Marius Stoica e, Francesca Sangiorgi a, ∗ Jack J. Middelburg a, Gareth R. Davies f, Wout Krijgsman a, a Department of Earth Sciences, Utrecht University, Princetonlaan 8A, 3584 CB, Utrecht, the Netherlands b Royal Netherlands Institute for Sea Research (NIOZ), 1790 AB Den Burg, Texel, and Utrecht University, the Netherlands c CASP, West Building, Madingley Rise, Madingley Road, Cambridge CB3 0UD, UK d Senckenberg Biodiversity and Climate Research Centre, Senckenberganlage 25, 60325, Frankfurt am Main, Germany e Department of Geology, University of Bucharest, Balcescu˘ Bd. 1, Bucharest, 010041, Romania f Geology & Geochemistry, VU University, De Boelelaan 1085, 1081 HV, Amsterdam, the Netherlands a r t i c l e i n f o a b s t r a c t Article history: During the so-called Messinian Salinity Crisis (MSC: 5.97-5.33 Myr ago), reduced exchange with the 3 Received 21 February 2019 Atlantic Ocean caused the Mediterranean to develop into a “saline giant” wherein ∼1 million km of Received in revised form 6 December 2019 evaporites (gypsum and halite) were deposited. Despite decades of research it is still poorly understood Accepted 10 December 2019 exactly how and where in the water column these evaporites formed. Gypsum formation commonly Available online 20 December 2019 requires enhanced dry conditions (evaporation exceeding precipitation), but recent studies also suggested Editor: I.
    [Show full text]