Does Large‐Scale Crustal Flow Shape the Eastern Margin of the Tibetan Plateau? Insights From Episodic Magmatism of Gongga‐Zheduo Granitic Massif

Abstract

The Tibetan Plateau was created by the India-Asia continental collision during the Cenozoic and is a natural laboratory to test models of continental tectonics. The mechanisms of crustal deformation, uplift, and outward expansion of the plateau are among the most controversial and unresolved aspects of the collision. The Asian block has experienced relatively diffuse deformation, located far away from the Indo-Asian suture zone (England & Houseman, 1986;England & Molnar, 1997). Some researchers have ascribed crustal thickening and outward expansion of the plateau as a result of escape tectonics along major strike-slip faults (Molnar & Tapponnier, 1975;Tapponnier et al., 2001). Others have proposed that the indentation of India is driving large-scale lower crustal flow and redistributing mass, to cause crustal thickening and outward expansion of the plateau (Clark & Royden, 2000;Royden et al., 1997).The large-scale (>1,000 km) crustal flow model can explain why there is high topography in the absence of significant crustal shortening and a low topographic gradient along the eastern margin of the Tibetan Plateau

Less‐Well‐Developed Crustal Channel‐Flow in the Central Tibetan Plateau Revealed by Receiver Function and Surface Wave Joint Inversion

“…Based on the differences in crustal compositional characteristics between central and eastern Tibet, Hu et al. (2022) constrain the existence of crustal channel‐flow by detecting whether the magma source of granitic rocks (from partial melting of the crust) in the eastern Tibetan Plateau contains the material characteristics of plateau interior. Their results show that the crustal materials in eastern Tibet does not originate from the migration of crustal material in the central Tibet, challenging the large‐scale crustal channel‐flow model, which are consistent with our results.…”

Crustal Structure and Anisotropy Measured by CHINArray and Implications for Complicated Deformation Mechanisms Beneath the Eastern Tibetan Margin

“…The lower crustal model is, however, not supported by geological data from the Longmenshan (LMS) range at the eastern edge of the plateau and its front (Hubbard & Shaw, 2009), which suggest that crustal shortening is the primary driver for the uplift of the LMS range. Hu et al (2022) conducted isotopic analyses of the igneous rocks at the eastern Tibet-Gongga-Zheduo Massif and found that the rocks are derived from partial melting of the local crust of SGB, instead of a distinct crust carried by a lower crust flow from the central plateau.…”

“…Hu et al. (2022) conducted isotopic analyses of the igneous rocks at the eastern Tibet‐Gongga‐Zheduo Massif and found that the rocks are derived from partial melting of the local crust of SGB, instead of a distinct crust carried by a lower crust flow from the central plateau.…”

Paleomagnetic studies of Jurassic and Cretaceous rocks in the Eastern Qiangtang Terrane, Tibetan Plateau, China

“…However, some other studies cast doubt on such a model: 3-D thermo-mechanical modeling suggests coupled deformation of the lower crust and underlying lithospheric mantle, without crustal flow (Chen & Gerya, 2016). Geochemical and isotopic studies into Cenozoic igneous rocks from the eastern margin of the Tibetan Plateau indicate that the mid-lower crust was locally derived rather than stemming from the Eastern Qiangtang Terrane (Hu et al, 2022). Rather surprisingly, the plan-view curvature in the orogens around the Eastern Himalayan Syntaxis (EHS) is rarely studied to date.…”