Anisotropy of Magnetic Susceptibility (AMS) Analysis of the Gonjo Basin as an Independent Constraint to Date Tibetan Shortening Pulses

Li, Shihu and van Hinsbergen, D.J.J. and Shen, Zhongshan and Najman, Yani and Deng, Chenglong L. and Zhu, Rixiang X. (2020) Anisotropy of Magnetic Susceptibility (AMS) Analysis of the Gonjo Basin as an Independent Constraint to Date Tibetan Shortening Pulses. Geophysical Research Letters, 47 (8). ISSN 0094-8276

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Abstract

The Tibetan Plateau accommodated major upper crustal shortening during Indian Plate oceanic and continental lithosphere subduction. Deciphering whether shortening was continuous or episodic, and how it correlates to major geodynamic changes is challenging. Here we apply anisotropy of magnetic susceptibility (AMS), a sensitive synsedimentary strain indicator, to a ~3 km thick magnetostratigraphically dated sedimentary section (69–41.5 Ma) in eastern Tibet. AMS shows “earliest deformation” fabrics from 69–52 Ma, followed by a sudden change to “pencil structure” fabrics with increasing anisotropy degree at ~52 Ma, dating a sudden increased synsedimentary shortening strain. This change coincides with enhanced sedimentation rates and synsedimentary vertical‐axis rotations of the Gonjo Basin, suggesting a causal link to a marked India‐Asia convergence rate deceleration. We show that AMS analysis provides a strong tool to distinguish between climatic and tectonic causes of sedimentological change and is an asset in identifying discrete tectonic pulses in intensely deformed terrane.

Item Type:
Journal Article
Journal or Publication Title:
Geophysical Research Letters
Additional Information:
An edited version of this paper was published by AGU. Copyright 2020 American Geophysical Union. Li, S., van Hinsbergen, D. J. J., Shen, Z., Najman, Y., Deng, C., & Zhu, R. ( 2020). Anisotropy of magnetic susceptibility (AMS) analysis of the Gonjo Basin as an independent constraint to date Tibetan shortening pulses. Geophysical Research Letters, 47, e2020GL087531. https://doi.org/10.1029/2020GL087531
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1900
Subjects:
ID Code:
143669
Deposited By:
Deposited On:
12 May 2020 14:45
Refereed?:
Yes
Published?:
Published
Last Modified:
05 Dec 2020 06:18