Charreau, Julien and Chen, Yan and Gilder, Stuart and Barrier, Laurie and Dominguez, Stéphane and Augier, Romain and Sen, Sevket and Avouac, Jean-Philippe and Gallaud, Audrey and Graveleau, Fabien and Wang, Qingchen (2009) Neogene uplift of the Tian Shan Mountains observed in the magnetic record of the Jingou River section (northwest China). Tectonics, 28 (2). TC2008. ISSN 0278-7407 http://resolver.caltech.edu/CaltechAUTHORS:20090721-095714948
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The Tian Shan Mountains constitute central Asia's longest and highest mountain range. Understanding their Cenozoic uplift history thus bears on mountain building processes in general, and on how deformation has occurred under the influence of the India-Asia collision in particular. In order to help decipher the uplift history of the Tian Shan, we collected 970 samples for magnetostratigraphic analysis along a 4571-m-thick section at the Jingou River (Xinjiang Province, China). Stepwise alternating field and thermal demagnetization isolate a linear magnetization component that is interpreted as primary. From this component, a magnetostratigraphic column composed of 67 polarity chrons are correlated with the reference geomagnetic polarity timescale between ∼1 Ma and ∼23.6 Ma, with some uncertainty below ∼21 Ma. This correlation places precise temporal control on the Neogene stratigraphy of the southern Junggar Basin and provides evidence for two significant stepwise increases in sediment accumulation rate at ∼16–15 Ma and ∼11–10 Ma. Rock magnetic parameters also undergo important changes at ∼16–15 Ma and ∼11–10 Ma that correlate with changes in sedimentary depositional environments. Together with previous work, we conclude that growth history of the modern Tian Shan Mountains includes two pulses of uplift and erosion at ∼16–15 Ma and ∼11–10 Ma. Middle to upper Tertiary rocks around the Tian Shan record very young (<∼5 Ma) counterclockwise paleomagnetic rotations, on the order of 15° to 20°, which are interpreted as because of strain partitioning with a component of sinistral shear that localized rotations in the piedmont.
|Additional Information:||© 2009 American Geophysical Union. Received 27 March 2008; accepted 15 December 2008; published 31 March 2009. The French program ECLIPSE, the Chinese project kzcx3-sw-147 and 973 2005CB422101, PRA (T05-02/T06-04) and ANR financed this study. We thank Guillaume Dupont-Nivet and an anonymous reviewer for their critical reviews that greatly improved the quality of the manuscript. This is IPGP contribution 2388. Index Terms: 1520 Geomagnetism and Paleomagnetism: Magnetostratigraphy; 1525 Geomagnetism and Paleomagnetism: Paleomagnetism applied to tectonics: regional, global; 8108 Tectonophysics: Continental tectonics: compressional.|
|Group:||Caltech Tectonics Observatory, Caltech Tectonics Observatory. Indo-Asian Collision Zone|
|Subject Keywords:||Tian Shan, uplift, erosion, magnetostratigraphy, AMS, sedimentology, rotation|
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|Official Citation:||Charreau, J., et al. (2009), Neogene uplift of the Tian Shan Mountains observed in the magnetic record of the Jingou River section (northwest China), Tectonics, 28, TC2008, doi:10.1029/2007TC002137.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||10 Aug 2009 17:25|
|Last Modified:||26 Dec 2012 11:05|
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