Evidence for northeastern Tibetan Plateau uplift between 25 and 20 Ma in the sedimentary archive of the Xining Basin, Northwestern China

详细信息    查看全文

• 作者：Guoqiao Xiao^a ; ^b ; Zhengtang Guo^c ; ^{ztguo@mail.iggcas.ac.cn} ; Guillaume Dupont-Nivet^d ; ^e ; ^f ; Houyuan Lu^c ; Naiqin Wu^c ; Junyi Ge^c ; Qingzhen Hao^c ; Shuzhen Peng^g ; Fengjiang Li^c ; Hemmo A. Abels^h ; Kexin Zhang^b
• 关键词：NE Tibet ; magnetostratigraphy ; tectonic uplift ; paleoclimate ; sedimentary provenance ; Xining Basin
• 刊名：Earth and Planetary Science Letters
• 出版年：2011
• 出版时间：15 December 2011
• 年：2011
• 卷：317-318
• 期：Complete
• 页码：185-195
• 全文大小：3892 K

文摘

The growth history of the Tibetan Plateau provides a valuable natural laboratory to understand tectonic processes of the India-Asia collision and their impact on and interactions with Asian and global climate change. However, both Tibetan Plateau growth and Asian paleoenvironments are generally poorly documented in pre-Pliocene times and reflect limited temporal coverage for different parts of the plateau. Here we present magnetostratigraphic results from the Xining Basin, at the NE margin of the Tibetan Plateau, precisely dating the record between the earliest Oligocene (~ 33 Ma) to the middle Miocene (~ 16 Ma). The pattern of observed paleomagnetic polarity zones is unequivocally correlated to the geomagnetic polarity time scale (GPTS) indicating relatively constant and low sediment accumulation rates (32 m/Myr) except for a peculiar period of unstable accumulation between 25.3 and 19.7 Ma. At the beginning of this interval, a marked permanent increase in magnetite content of the sediments is observed and likely relates to a change in provenance. We directly relate this unstable period of sediment accumulation and provenance change to the coeval exhumation recently reported by low-temperature thermochronology from the Laji Shan range, which subsequently formed the southern margin of the Xining Basin. Evidence for NE Tibet tectonism at 25-20 Ma can be associated with widespread deformation over the entire Himalayan-Tibetan orogen at this time, which may be linked to the coeval appearance of monsoon climate in Eastern Asia and the onset of central Asian desertification.