TY - JOUR A1 - Zhang, Yang A1 - Huang, Wentao A1 - Huang, Baochun A1 - van Hinsbergen, Douwe J. J. A1 - Yang, Tao A1 - Dupont-Nivet, Guillaume A1 - Guo, Zhaojie T1 - 53-43Ma Deformation of Eastern Tibet Revealed by Three Stages of Tectonic Rotation in the Gongjue Basin JF - Journal of geophysical research : Solid earth N2 - The Gongjue basin from the eastern Qiangtang terrane is located in the transition region where the regional structural lineation curves from east-west-oriented in Tibet to north-south-oriented in Yunnan. In this study, we sampled the red beds in the basin from the lower Gongjue to upper Ranmugou formations for the first time covering the entire stratigraphic profile. The stratigraphic ages are bracketed within 53-43Ma by new detrital zircon U-Pb ages constraining the maximum deposition age to 52.51.5Ma. Rock magnetic and petrographic studies indicate that detrital magnetite and hematite are the magnetic carriers. Positive reversals and fold tests demonstrate that the characteristic remanent magnetization has a primary origin. The Gongjue and Ranmugou formations yield mean characteristic remanent magnetization directions of D-s/I-s=31.0 degrees/21.3 degrees and D-s/I-s=15.9 degrees/22.0 degrees, respectively. The magnetic inclination of these characteristic remanent magnetizations is significantly shallowed compared to the expected inclination for the locality. However, the elongation/inclination correction method does not provide a meaningful correction, likely because of syn-depositional rotation. Rotations relative to the Eurasian apparent polar wander path occurred in three stages: Stage I, 33.33.4 degrees clockwise rotation during the deposition of the Gongjue and lower Ranmugou formations; Stage II, 26.93.7 degrees counterclockwise rotation during deposition of the lower and middle Ranmugou formation; and Stage III, 17.73.3 degrees clockwise rotation after 43Ma. The complex rotation history recorded in the basin is possibly linked to sinistral shear along the Qiangtang block during India indentation into Asia and the early stage of the extrusion of the northwestern Indochina blocks away from eastern Tibet. KW - eastern Qiangtang terrane KW - Gongjue basin KW - paleomagnetism KW - inclination shallowing KW - rotation Y1 - 2018 U6 - https://doi.org/10.1002/2018JB015443 SN - 2169-9313 SN - 2169-9356 VL - 123 IS - 5 SP - 3320 EP - 3338 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Woutersen, Amber A1 - Jardine, Phillip E. A1 - Giovanni Bogota-Angel, Raul A1 - Zhang, Hong-Xiang A1 - Silvestro, Daniele A1 - Antonelli, Alexandre A1 - Gogna, Elena A1 - Erkens, Roy H. J. A1 - Gosling, William D. A1 - Dupont-Nivet, Guillaume A1 - Hoorn, Carina T1 - A novel approach to study the morphology and chemistry of pollen in a phylogenetic context, applied to the halophytic taxon Nitraria L.(Nitrariaceae) JF - PeerJ N2 - Nitraria is a halophytic taxon (i.e., adapted to saline environments) that belongs to the plant family Nitrariaceae and is distributed from the Mediterranean, across Asia into the south-eastern tip of Australia. This taxon is thought to have originated in Asia during the Paleogene (66-23 Ma), alongside the proto-Paratethys epicontinental sea. The evolutionary history of Nitraria might hold important clues on the links between climatic and biotic evolution but limited taxonomic documentation of this taxon has thus far hindered this line of research. Here we investigate if the pollen morphology and the chemical composition of the pollen wall are informative of the evolutionary history of Nitraria and could explain if origination along the proto-Paratethys and dispersal to the Tibetan Plateau was simultaneous or a secondary process. To answer these questions, we applied a novel approach consisting of a combination of Fourier Transform Infrared spectroscopy (FTIR), to determine the chemical composition of the pollen wall, and pollen morphological analyses using Light Microscopy (LM) and Scanning Electron Microscopy (SEM). We analysed our data using ordinations (principal components analysis and non-metric multidimensional scaling), and directly mapped it on the Nitrariaceae phylogeny to produce a phylomorphospace and a phylochemospace. Our LM, SEM and FTIR analyses show clear morphological and chemical differences between the sister groups Peganum and Nitraria. Differences in the morphological and chemical characteristics of highland species (Nitraria schoberi, N. sphaerocarpa, N. sibirica and N. tangutorum) and lowland species (Nitraria billardierei and N. retusa) are very subtle, with phylogenetic history appearing to be a more important control on Nitraria pollen than local environmental conditions. Our approach shows a compelling consistency between the chemical and morphological characteristics of the eight studied Nitrariaceae species, and these traits are in agreement with the phylogenetic tree. Taken together, this demonstrates how novel methods for studying fossil pollen can facilitate the evolutionary investigation of living and extinct taxa, and the environments they represent. KW - FTIR KW - LM KW - SEM KW - Paratethys KW - Tibet KW - Sporopollenin KW - Mediterranean KW - Steppe-desert KW - Australia KW - Palynology Y1 - 2018 U6 - https://doi.org/10.7717/peerj.5055 SN - 2167-8359 VL - 6 PB - PeerJ Inc. CY - London ER - TY - JOUR A1 - Bougeois, Laurie A1 - Dupont-Nivet, Guillaume A1 - de Rafelis, Marc A1 - Tindall, Julia C. A1 - Proust, Jean-Noel A1 - Reichart, Gert-Jan A1 - de Nooijer, Lennart J. A1 - Guo, Zhaojie A1 - Ormukov, Cholponbelk T1 - Asian monsoons and aridification response to Paleogene sea retreat and Neogene westerly shielding indicated by seasonality in Paratethys oysters JF - Earth and planetary science letters N2 - Asian climate patterns, characterised by highly seasonal monsoons and continentality, are thought to originate in the Eocene epoch (56 to 34 million years ago - Ma) in response to global climate, Tibetan Plateau uplift and the disappearance of the giant Proto-Paratethys sea formerly extending over Eurasia. The influence of this sea on Asian climate has hitherto not been constrained by proxy records despite being recognised as a major driver by climate models. We report here strongly seasonal records preserved in annual lamina of Eocene oysters from the Proto-Paratethys with sedimentological and numerical data showing that monsoons were not dampened by the sea and that aridification was modulated by westerly moisture sourced from the sea. Hot and arid summers despite the presence of the sea suggest a strong anticyclonic zone at Central Asian latitudes and an orographic effect from the emerging Tibetan Plateau. Westerly moisture precipitating during cold and wetter winters appear to have decreased in two steps. First in response to the late Eocene (34-37 Ma) sea retreat; second by the orogeny of the Tian Shan and Pamir ranges shielding the westerlies after 25 Ma. Paleogene sea retreat and Neogene westerly shielding thus provide two successive mechanisms forcing coeval Asian desertification and biotic crises. KW - Eocene monsoon KW - aridification KW - Paratethys sea KW - Central Asia KW - seasonality KW - bivalves Y1 - 2018 U6 - https://doi.org/10.1016/j.epsl.2017.12.036 SN - 0012-821X SN - 1385-013X VL - 485 SP - 99 EP - 110 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Licht, Alexis A1 - van Cappelle, M. A1 - Abels, Hemmo A. A1 - Ladant, Jean-Baptiste A1 - Trabucho-Alexandre, J. A1 - France-Lanord, C. A1 - Donnadieu, Yannick A1 - Vandenberghe, J. A1 - Rigaudier, T. A1 - Lecuyer, C. A1 - Terry, D. A1 - Adriaens, R. A1 - Boura, A. A1 - Guo, Z. A1 - Soe, Aung Naing A1 - Quade, J. A1 - Dupont-Nivet, Guillaume A1 - Jaeger, J. -J. T1 - Asian monsoons in a late Eocene greenhouse world JF - Nature : the international weekly journal of science N2 - The strong present-day Asian monsoons are thought to have originated between 25 and 22 million years (Myr) ago, driven by Tibetan-Himalayan uplift. However, the existence of older Asian monsoons and their response to enhanced greenhouse conditions such as those in the Eocene period (55-34Myrago) are unknown because of the paucity of well-dated records. Here we show late Eocene climate records revealing marked monsoon-like patterns in rainfall and wind south and north of the Tibetan-Himalayan orogen. This is indicated by low oxygen isotope values with strong seasonality in gastropod shells and mammal teeth from Myanmar, and by aeolian dust deposition in northwest China. Our climate simulations support modern-like Eocene monsoonal rainfall and show that a reinforced hydrological cycle responding to enhanced greenhouse conditions counterbalanced the negative effect of lower Tibetan relief on precipitation. These strong monsoons later weakened with the global shift to icehouse conditions 34 Myr ago. Y1 - 2014 U6 - https://doi.org/10.1038/nature13704 SN - 0028-0836 SN - 1476-4687 VL - 513 IS - 7519 SP - 501 EP - + PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Westerweel, Jan A1 - Roperch, Pierrick A1 - Licht, Alexis A1 - Dupont-Nivet, Guillaume A1 - Win, Zaw A1 - Poblete, Fernando A1 - Ruffet, Gilles A1 - Swe, Hnin Hnin A1 - Thi, Myat Kai A1 - Aung, Day Wa T1 - Burma Terrane part of the Trans-Tethyan arc during collision with India according to palaeomagnetic data JF - Nature geoscience N2 - Convergence between the Indian and Asian plates has reshaped large parts of Asia, changing regional climate and biodiversity, yet geodynamic models fundamentally diverge on how convergence was accommodated since the India-Asia collision. Here we report palaeomagnetic data from the Burma Terrane, which is at the eastern edge of the collision zone and is famous for its Cretaceous amber biota, to better determine the evolution of the India-Asia collision. The Burma Terrane was part of a Trans-Tethyan island arc and stood at a near-equatorial southern latitude at similar to 95 Ma, suggesting island endemism for the Burmese amber biota. The Burma Terrane underwent significant clockwise rotation between similar to 80 and 50 Ma, causing its subduction margin to become hyper-oblique. Subsequently, it was translated northward on the Indian Plate by an exceptional distance of at least 2,000 km along a dextral strike-slip fault system in the east. Our reconstructions are only compatible with geodynamic models involving an initial collision of India with a near-equatorial Trans-Tethyan subduction system at similar to 60 Ma, followed by a later collision with the Asian margin. Y1 - 2019 U6 - https://doi.org/10.1038/s41561-019-0443-2 SN - 1752-0894 SN - 1752-0908 VL - 12 IS - 10 SP - 863 EP - 868 PB - Nature Publ. Group CY - New York ER - TY - JOUR A1 - Huang, Wentao A1 - Dupont-Nivet, Guillaume A1 - Lippert, Peter C. A1 - van Hinsbergen, Douwe J. J. A1 - Dekkers, Mark J. A1 - Guo, Zhaojie A1 - Waldrip, Ross A1 - Li, Xiaochun A1 - Zhang, Xiaoran A1 - Liu, Dongdong A1 - Kapp, Paul T1 - Can a primary remanence be retrieved from partially remagnetized Eocence volcanic rocks in the Nanmulin Basin (southern Tibet) to date the India-Asia collision? JF - Journal of geophysical research : Solid earth N2 - Paleomagnetic dating of the India-Asia collision hinges on determining the Paleogene latitude of the Lhasa terrane (southern Tibet). Reported latitudes range from 5 degrees N to 30 degrees N, however, leading to contrasting paleogeographic interpretations. Here we report new data from the Eocene Linzizong volcanic rocks in the Nanmulin Basin, which previously yielded data suggesting a low paleolatitude (similar to 10 degrees N). New zircon U-Pb dates indicate an age of similar to 52Ma. Negative fold tests, however, demonstrate that the isolated characteristic remanent magnetizations, with notably varying inclinations, are not primary. Rock magnetic analyses, end-member modeling of isothermal remanent magnetization acquisition curves, and petrographic observations are consistent with variable degrees of posttilting remagnetization due to low-temperature alteration of primary magmatic titanomagnetite and the formation of secondary pigmentary hematite that unblock simultaneously. Previously reported paleomagnetic data from the Nanmulin Basin implying low paleolatitude should thus not be used to estimate the time and latitude of the India-Asia collision. We show that the paleomagnetic inclinations vary linearly with the contribution of secondary hematite to saturation isothermal remanent magnetization. We tentatively propose a new method to recover a primary remanence with inclination of 38.1 degrees (35.7 degrees, 40.5 degrees) (95% significance) and a secondary remanence with inclination of 42.9 degrees (41.5 degrees,44.4 degrees) (95% significance). The paleolatitude defined by the modeled primary remanence21 degrees N (19.8 degrees N, 23.1 degrees N)is consistent with the regional compilation of published results from pristine volcanic rocks and sedimentary rocks of the upper Linzizong Group corrected for inclination shallowing. The start of the Tibetan Himalaya-Asia collision was situated at similar to 20 degrees N and took place by similar to 50Ma. KW - remagnetization KW - paleomagnetism applied to tectonics KW - rock and mineral magnetism KW - India-Asia collision Y1 - 2015 U6 - https://doi.org/10.1002/2014JB011599 SN - 2169-9313 SN - 2169-9356 VL - 120 IS - 1 SP - 42 EP - 66 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Barbolini, Natasha A1 - Woutersen, Amber A1 - Dupont-Nivet, Guillaume A1 - Silvestro, Daniele A1 - Tardif-Becquet, Delphine A1 - Coster, Pauline M. C. A1 - Meijer, Niels A1 - Chang, Cun A1 - Zhang, Hou-Xi A1 - Licht, Alexis A1 - Rydin, Catarina A1 - Koutsodendris, Andreas A1 - Han, Fang A1 - Rohrmann, Alexander A1 - Liu, Xiang-Jun A1 - Zhang, Y. A1 - Donnadieu, Yannick A1 - Fluteau, Frederic A1 - Ladant, Jean-Baptiste A1 - Le Hir, Guillaume A1 - Hoorn, M. Carina T1 - Cenozoic evolution of the steppe-desert biome in Central Asia JF - Science Advances N2 - The origins and development of the arid and highly seasonal steppe-desert biome in Central Asia, the largest of its kind in the world, remain largely unconstrained by existing records. It is unclear how Cenozoic climatic, geological, and biological forces, acting at diverse spatial and temporal scales, shaped Central Asian ecosystems through time. Our synthesis shows that the Central Asian steppe-desert has existed since at least Eocene times but experienced no less than two regime shifts, one at the Eocene-Oligocene Transition and one in the mid-Miocene. These shifts separated three successive "stable states," each characterized by unique floral and faunal structures. Past responses to disturbance in the Asian steppe-desert imply that modern ecosystems are unlikely to recover their present structures and diversity if forced into a new regime. This is of concern for Asian steppes today, which are being modified for human use and lost to desertification at unprecedented rates. Y1 - 2020 U6 - https://doi.org/10.1126/sciadv.abb8227 SN - 2375-2548 VL - 6 IS - 41 PB - American Association for the Advancement of Science CY - Washington ER - TY - JOUR A1 - Meijer, Niels A1 - Dupont-Nivet, Guillaume A1 - Abels, Hemmo A. A1 - Kaya, Mustafa Y. A1 - Licht, Alexis A1 - Xiao, Meimei A1 - Zhang, Yang A1 - Roperch, Pierrick A1 - Poujol, Marc A1 - Lai, Zhongping A1 - Guo, Zhaojie T1 - Central Asian moisture modulated by proto-Paratethys Sea incursions since the early Eocene JF - Earth and planetary science letters N2 - The establishment and evolution of the Asian monsoons and arid interior have been linked to uplift of the Tibetan Plateau, retreat of the inland proto-Paratethys Sea and global cooling during the Cenozoic. However, the respective role of these driving mechanisms remains poorly constrained. This is partly due to a lack of continental records covering the key Eocene epoch marked by the onset of Tibetan Plateau uplift, proto-Paratethys Sea incursions and long-term global cooling. In this study, we reconstruct paleoenvironments in the Xining Basin, NE Tibet, to show a long-term drying of the Asian continental interior from the early Eocene to the Oligocene. Superimposed on this trend are three alternations between arid mudflat and wetter saline lake intervals, which are interpreted to reflect atmospheric moisture fluctuations in the basin. We date these fluctuations using magnetostratigraphy and the radiometric age of an intercalated tuff layer. The first saline lake interval is tentatively constrained to the late Paleocene-early Eocene. The other two are firmly dated between similar to 46 Ma (top magnetochron C21n) and similar to 41 Ma (base C18r) and between similar to 40 Ma (base C18n) and similar to 37 Ma (top C17n). Remarkably, these phases correlate in time with highstands of the proto-Paratethys Sea. This strongly suggests that these sea incursions enhanced westerly moisture supply as far inland as the Xining Basin. We conclude that the proto-Paratethys Sea constituted a key driver of Asian climate and should be considered in model and proxy interpretations. (C) 2019 Elsevier B.V. All rights reserved. KW - Paleogene KW - magnetostratigraphy KW - Central Asia KW - Xining Basin KW - westerlies KW - Asian monsoon Y1 - 2019 U6 - https://doi.org/10.1016/j.epsl.2018.12.031 SN - 0012-821X SN - 1385-013X VL - 510 SP - 73 EP - 84 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Huang, Wentao A1 - Jackson, Michael J. A1 - Dekkers, Mark J. A1 - Zhang, Yang A1 - Zhang, Bo A1 - Guo, Zhaojie A1 - Dupont-Nivet, Guillaume T1 - Challenges in isolating primary remanent magnetization from Tethyan carbonate rocks on the Tibetan Plateau: Insight from remagnetized Upper Triassic limestones in the eastern Qiangtang block JF - Earth & planetary science letters N2 - Carbonate rocks, widely used for paleomagnetically quantifying the drift history of the Gondwana derived continental blocks of the Tibetan Plateau and evolution of the Paleo/Meso/Neo-Tethys Oceans, are prone to pervasive remagnetization. Identifying remagnetization is difficult because it is commonly undetectable through the classic paleomagnetic field tests. Here we apply comprehensive paleomagnetic, rock magnetic, and petrographic studies to upper Triassic limestones in the eastern Qiangtang block. Our results reveal that detrital/biogenic magnetite, which may carry the primary natural remanent magnetization (NRM), is rarely preserved in these rocks. In contrast, authigenic magnetite and hematite pseudomorphs after pyrite, and monoclinic pyrrhotite record three episodes of remagnetization. The earliest remagnetization was induced by oxidation of early diagenetic pyrite to magnetite, probably related to the collision between the northeastern Tibetan Plateau and the Qiangtang block after closure of the Paleo-Tethys Ocean in the Late Triassic. The second remagnetization, residing in hematite and minor goethite, which is the further subsurface oxidation product of pyrite/magnetite, is possibly related to the development of the localized Cenozoic basins soon after India-Asia collision in the Paleocene. The youngest remagnetization is a combination of thermoviscous and chemical remanent magnetization carried by authigenic magnetite and pyrrhotite, respectively. Our analyses suggest that a high supply of organic carbon during carbonate deposition, prevailing sulfate reducing conditions during early diagenesis, and widespread orogenic fluid migration related to crustal shortening during later diagenesis, have altered the primary remanence of the shallow-water Tethyan carbonate rocks of the Tibetan Plateau. We emphasize that all paleomagnetic results from these rocks must be carefully examined for remagnetization before being used for paleogeographic reconstructions. Future paleomagnetic investigations of the carbonate rocks in orogenic belts should be accompanied by thorough rock magnetic and petrographic studies to determine the origin of the NRM. (C) 2019 Elsevier B.V. All rights reserved. KW - Triassic limestone KW - remagnetization KW - Tibetan Plateau Y1 - 2019 U6 - https://doi.org/10.1016/j.epsl.2019.06.035 SN - 0012-821X SN - 1385-013X VL - 523 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Deino, Alan L. A1 - Sier, Mark Jan A1 - Garello, Dominique A1 - Keller, B. A1 - Kingston, John A1 - Scott, Jennifer J. A1 - Dupont-Nivet, Guillaume A1 - Cohen, Andrew T1 - Chronostratigraphy of the Baringo-Tugen-Barsemoi (HSPDP-BTB13-1A) core-Ar-40/Ar-39 dating, magnetostratigraphy, tephrostratigraphy, sequence stratigraphy and Bayesian age modeling JF - Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences N2 - The Baringo-Tugen-Barsemoi 2013 drillcore (BTB13), acquired as part of the Hominin Sites and Paleolakes Drilling Project, recovered 228 m of fluviolacustrine sedimentary rocks and tuffs spanning a similar to 3.29-2.56 Ma interval of the highly fossiliferous and hominin-bearing Chemeron Formation, Tugen Hills, Kenya. Here we present a Bayesian stratigraphic age model for the core employing chronostratigraphic control points derived from Ar-40/Ar-39 dating of tuffs from core and outcrop, Ar-40/Ar-39 age calibration of related outcrop diatomaceous units, and core magnetostratigraphy. The age model reveals three main intervals with distinct sediment accumulation rates: an early rapid phase from 3.2 to 2.9 Ma; a relatively slow phase from 2.9 to 2.7 Ma; and the highest rate of accumulation from 2.7 to 2.6 Ma. The intervals of rapid accumulation correspond to periods of high Earth orbital eccentricity, whereas the slow accumulation interval corresponds to low eccentricity at 2.9-2.7 Ma, suggesting that astronomically mediated climate processes may be responsible for the observed changes in sediment accumulation rate. Lacustrine transgression-regression events, as delineated using sequence stratigraphy, dominantly operate on precession scale, particularly within the high eccentricity periods. A set of erosively based fluvial conglomerates correspond to the 2.9-2.7 Ma interval, which could be related to either the depositional response to low eccentricity or to the development of unconformities due to local tectonic activity. Age calibration of core magnetic susceptibility and gamma density logs indicates a close temporal correspondence between a shift from high- to low-frequency signal variability at similar to 3 Ma, approximately coincident the end of the mid-Piacenzian Warm Period, and the beginning of the cooling of world climate leading to the initiation of Northern Hemispheric glaciation c. 2.7 Ma. BTB13 and the Baringo Basin records may thus provide evidence of a connection between high-latitude glaciation and equatorial terrestrial climate toward the end of the Pliocene. KW - Chemeron Formation KW - Pliocene KW - Eccentricity KW - Precession KW - Paleoclimate KW - Paleolimnology Y1 - 2019 U6 - https://doi.org/10.1016/j.palaeo.2019.109258 SN - 0031-0182 SN - 1872-616X VL - 532 PB - Elsevier CY - Amsterdam ER -