HR: 1340h
AN: T23C-1531    [Abstracts]
TI: Eocene-Oligocene aridification and uplift of the Tibetan Plateau, insight from chronostratigraphic and pollen analysis
AU: Hoorn, C
EM: carina.hoorn@milne.cc
AF: Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, K008, Kruislaan 314, Amsterdam, 1098, Netherlands
AU: * Dupont-Nivet, G
EM: gdn@geo.uu.nl
AF: Paleomagnetic Laboratory "Fort Hoofddijk", Faculty of Geosciences, Utrecht University, Budapestlaan 17, Utrecht, 3584 CD, Netherlands
AU: Konert, M
EM: martin.konert@falw.vu.nl
AF: Sediment analysis laboratory, Faculty of Earth- and Life Sciences (FALW), Vrije Universiteit Amsterdam, De Boelelaan 1085, Amsterdam, 1081 HV, Netherlands
AU: Krijgsman, W
EM: krijgsma@geo.uu.nl
AF: Paleomagnetic Laboratory "Fort Hoofddijk", Faculty of Geosciences, Utrecht University, Budapestlaan 17, Utrecht, 3584 CD, Netherlands
AU: Langereis, C
EM: langer@geo.uu.nl
AF: Paleomagnetic Laboratory "Fort Hoofddijk", Faculty of Geosciences, Utrecht University, Budapestlaan 17, Utrecht, 3584 CD, Netherlands
AU: Abels, H
EM: abels@geo.uu.nl
AF: Stratigraphy-Paleontology, Faculty of Geosciences, Utrecht University, Budapestlaan 4, Utrecht, 3584 CD, Netherlands
AU: Dai, S
EM: daisher@lzu.edu.cn
AF: Key Laboratory of Western China's Environmental Systems, Ministry of Education of China & College of Resources and Environment, Lanzhou University, Lanzhou, 730000, China
AU: Fang, X
EM: fangxm@itpcas.ac.cn
AF: Key Laboratory of Western China's Environmental Systems, Ministry of Education of China & College of Resources and Environment, Lanzhou University, Lanzhou, 730000, China
AU: Fang, X
EM: fangxm@itpcas.ac.cn
AF: Institute of Tibetan Plateau Research, Chinese Academy of Science, P.O. Box 2871, Beijing, 100085, China
AB: Continental aridification and the intensification of the monsoons in Asia are generally attributed to uplift of the Tibetan plateau and to the land–sea redistributions associated with the continental collision of India and Asia, whereas some studies suggest that past changes in Asian environments are mainly governed by global climate. The most dramatic climate event since the onset of the collision of India and Asia is the Eocene-Oligocene transition, an abrupt cooling step associated with the onset of glaciation in Antarctica 34 million years ago. However, the influence of this global event on Asian environments is poorly understood. Using magnetostratigraphy and cyclostratigraphy, we showed that aridification, which is indicated by the disappearance of playa lake deposits in the northeastern Tibetan plateau, occurred precisely at the time of the Eocene–Oligocene transition (Dupont-Nivet et al., 2007, Nature vol. 445, p. 637-638). This result suggest that this global transition is linked to significant aridification and cooling in continental Asia recorded by palaeontological and palaeoenvironmental changes, and thus support the idea that global cooling is associated with the Eocene–Oligocene transition. New insight is provided by preliminary pollen data recovered from gypsiferous beds of the playa deposits. The sudden and regional appearances of representatives of the Pinaceae family -and in particular that of Picea- which dominate the palynological record is interpreted to indicate a change to cooler and/or higher altitude conditions in surrounding paleoenvironments. This change occurring at ca. 38 Ma, predates by 4 My the major Eocene-Oligocene aridification but is in close correspondence to increasing sediment accumulation rates and tectonic rotations (see Dai et al., this meeting, Session GP12) and may thus be related to regional Tibetan uplift.
UR: http://www.geo.uu.nl/~forth/people/Guillaume
DE: 1535 Reversals: process, timescale, magnetostratigraphy
DE: 4910 Astronomical forcing
DE: 4952 Palynology
DE: 8108 Continental tectonics: compressional
DE: 8177 Tectonics and climatic interactions
SC: Tectonophysics [T]
MN: 2007 Fall Meeting