Stepwise northward compression in the northeastern Tibetan Plateau: Insights from the chronology of the Baima Basin

• Published in: Global and planetary change 2023-01, Vol.220, p.104015, Article 104015
• Main Authors: Liang, Hao, Zhang, Ke, Fu, Jianli, Wang, Weitao, Zhang, Peizhen, Grapes, Rodney, Ma, Zhanwu, Zhang, Yipeng, Li, Zhigang, Yan, Yonggang, Hui, Gege, Sun, Chuang, Xu, Binbin, Li, Zhongyun, Zheng, Wenjun, Tian, Qingying
• Format: Article
• Language: English
• Subjects: Cosmogenic dating; Forward propagation; Magnetostratigraphy; Northeastern Tibetan Plateau
• ISSN: 0921-8181; 1872-6364
• DOI: 10.1016/j.gloplacha.2022.104015

Intense compression following the India-Asia collision is responsible for basin sedimentation and deformation in the northeastern Tibetan Plateau. Despite significant advances in elucidating basin development and associated deformation, debate continues regarding the onset of basin sedimentation along the plateau margin. One of the debated issues is whether the Cenozoic basin sedimentation was a response to deformation soon after plate collision at approximately 50 Ma, or if it was related to a former stress field overprinted by an expanded plateau 20–30 Ma later. To address this issue, a complete spatiotemporal pattern of deformation is central to understanding the basin development linked to plateau growth. Here, we report new deformation constraints in the Baima Basin, a depocenter located on the northern margin of the Arcuate Ranges area (AR), northeastern Tibetan Plateau. A combination of high-resolution magnetostratigraphic results, 10Be/26Al cosmogenic nuclide burial ages and previous chronological constraints provides a prolonged sedimentary history, containing the onset of a N–S-trending normal-faulting basin in the late Eocene, basin subsidence for predominant deposition at 13.6–6.0 Ma and dextral transpression since 6.0 Ma. In the predominant deposition stage, the basin accumulated upward fining sediments under a relatively stable climate context. Dextral transpression along the N–S-striking fault disrupted the once prevailing subsidence at ca. 6.0 Ma, resulting in growth strata, an increase in coarse-grained deposits and lower accumulation rates in the Baima Basin. Dextral strike-slip was probably caused by stepwise forward propagation beginning approximately 8 Ma in the AR, which may be related to late Miocene plateau-scale strike-slip motion. These new data imply that predominant sedimentation and basin deformation in response to plateau expansion could have occurred much later than the onset of the basin. •Predominant basin sedimentation by normal faulting prevailed around ca. 13–8 Ma.•Stepwise forward compression overprinted the normal-faulting basins since ca. 8 Ma.•Growth strata indicate northward compression since ca. 6 Ma in the Baima Basin.