HR: 16:15h
AN: GP54A-02 INVITED    [Abstracts]
TI: Toward a Revised Middle Jurassic Reconstruction of the Eurasian Landmass
AU: * Gilder, S
EM: gilder@lmu.de
AF: Ludwig Maximilians University, Department of Earth and Environmental Sciences, Theresienstrasse 41, Munich, 80333, Germany
AU: Gomez, J
EM: julia.gomez@ens-lyon.fr
AF: Ecole Normale Superieur de Lyon, Laboratoire de Sciences de la Terre, 46 Allee d'Italie, Lyon, 69364, France
AU: Chen, Y
EM: Yan.Chen@univ-orleans.fr
AF: Universite d'Orleans, Departement des Sciences de la Terre, B.P. 6759, Orleans, 45067, France
AU: Cogne, J
EM: cogne@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, Laboratoire de Paleomagnetisme, 4 place Jussieu, Paris, 75252, France
AB: New Permian and Middle Jurassic paleomagnetic data from the Tarim Basin pose a paradox. Their declinations are identical to Upper Carboniferous to Neogene rocks collected from the same section, and their inclinations are similar to today's. When assuming that lower than expected inclinations in continental sediments arise from inclination shallowing effects, then the paleolatitudes of all Upper Carboniferous to Present rocks from Tarim are indistinguishable. After accounting for local vertical axis block rotations occurring in the last 20 million years, these observations suggest that Tarim experienced no apparent polar wander since the Carboniferous. Our Middle Jurassic pole positions Tarim 23.6±8.4° farther south than that predicted from the coeval reference pole for Eurasia; however, no geological argument exists to support the closure of a large ocean basin between Tarim and Siberia since the Middle Jurassic. We conclude that Tarim has experienced little or no apparent polar wander since the Carboniferous. Moreover, we propose a new Middle Mesozoic reconstruction of Eurasia using the new Middle Jurassic pole from Tarim. Our reconstruction results in a more geologically compatible solution for the eastern Asian blocks over previous reconstructions.
DE: 1520 Magnetostratigraphy
DE: 1525 Paleomagnetism applied to tectonics: regional, global
DE: 1527 Paleomagnetism applied to geologic processes
DE: 8104 Continental margins: convergent
DE: 8106 Continental margins: transform
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting