Quantifying the rise of the Himalaya orogen and implications for the South Asian monsoon

This data set is from the paper: Ding, L., Spicer, R.A., Yang, J., Xu, Q., Cai, F.L., Li, S., Lai, q.z., Wang, H.Q., Spicer, t.e.v., Yue, Y.H., Shukla, A., Srivastava, g., Khan, M.A., BERA, S., and Mehrotra, R. 2017. Quantifying the rise of the Himalaya origin and implications for the South Asian monsoon. Geography, 45:215-218. This achievement is part of a series of research results of paleoaltitude carried out by Ding Lin' team. We reconstruct the rise of a segment of the southern flank of the Himalaya-Tibet orogen, to the south of the Lhasa terrane, using a paleoaltimeter based on paleoenthalpy encoded in fossil leaves from two new assemblages in southern Tibet (Liuqu and Qiabulin) and four previously known floras from the Himalaya foreland basin. U-Pb dating of zircons constrains the Liuqu flora to the latest Paleocene (ca. 56 Ma) and the Qiabulin flora to the earliest Miocene (21–19 Ma). The proto-Himalaya grew slowly against a high (~4 km) proto–Tibetan Plateau from ~1 km in the late Paleocene to ~2.3 km at the beginning of the Miocene, and achieved at least ~5.5 km by ca. 15 Ma. Contrasting precipitation patterns between the Himalaya-Tibet edifice and the Himalaya foreland basin for the past ~56 m.y. show progressive drying across southern Tibet, seemingly linked to the uplift of the Himalaya orogen.

0 2020-03-24

Paleomagnetic data bearing on the Mesozoic deformation of the Qiangtang Block: Implications for the evolution of the Paleo- and Meso-Tethys

Paleomagnetism has played an important role in quantifying the Mesozoic evolution of “Proto-Tibet”. We present here our recent paleomagnetic data from five Middle-Upper Jurassic sedimentary sequences of the eastern North Qiangtang Terrane at Yanshiping. The new paleomagnetic results from 99 sites, 1,702 samples and reveal paleopoles at 79.1°N/306.9°E (dp=3.9°, dm=6.3°) for Quemo Co Fm, 68.9°N/313.8°E (dp=2.1°, dm=3.7°) for Buqu Fm, 66.1°N/332.1°E (dp=2.7°, dm=4.6°) for Xiali Fm, 72.4°N/318.6°E (dp=3.9°, dm=6.7°) for Suowa Fm, and 76.9°N/301.1°E (dp=7.9°, dm=13.2°) for Xueshan Fm, respectively. These results indicate that Yanshiping experienced latitudinal changes from ~24.5° N to ~22.0º N over the time interval 171.2 - <157.5 Ma, accompanied by clockwise (CW) rotations of ~19.8±9.4º between ~171.2 and 161.7 Ma and counterclockwise (CCW) rotations of ~15.4±13.4º between ~161.7 and <157.2 Ma. We attribute the change in rotation sense at approximately ~161.7 Ma to the initial collision of the Lhasa and Qiangtang terranes. Using this and other paleomagnetic data from the Lhasa, Qiangtang and Tarim terranes, as well as other geological evidence, such as tectonism-related sedimentary sequences, volcanism, and HP metamorphism, we propose a new conceptual evolution model for the Mesozoic QT and Tethyan Oceans, including 3 intra-continental collisions (South-North Qiangtang, Qiangtang-Songpan-Ganzi and Lhasa-Qiangtang) and post collisional extensions.

0 2019-12-19