12 The Geodynamic Evolution of the Himalaya: From Mountain Building to Modern Seismicity and Climate Change
The Himalaya are an active mountain chain whose geology affects people in more than six Asian countries. This interdisciplinary session focuses on the geodynamics of the region as well as the impact of modern seismicity and climate change
Sunday, 19 October 2025
8:00 AM - 12:00 PM
HBGCC, 217B
Surface Uplift of the Gangdese Arc During the Subduction–Collision Transition: Insights from Numerical Modeling
Paper number: 12-6
Program: Technical Sessions
Time: 9:15 AM – 9:30 AM
Authors
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Xincheng Zhou Presenting AuthorDepartment of Geological Sciences and Engineering, Nevada Geosciences, University of Nevada, Reno, Reno, NV
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Wenrong CaoDepartment of Geological Sciences and Engineering, Nevada Geosciences, University of Nevada, Reno, Reno, NV
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Jianfeng YangState Key Laboratory of Lithospheric and Environmental Coevolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China, Beijing
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Kaus BorisInstitute for Geosciences, Johannes Gutenberg-Universität Mainz, Mainz, Germany, Mainz
Abstract
The timing and magnitude of surface uplift and crustal evolution of the proto-Tibetan Plateau are under debate during the transition from the Tethyan oceanic subduction to India-Asia continental collision (~60–45 Ma). In particular, the Gangdese arc located on the southernmost Eurasian plate margin, shows a ~2-3 km apparent elevational discrepancy between geochemical proxies-derived elevation and stable isotope-based paleo-altimetry during 57–48 Ma. Here, we employ thermo-mechanical numerical modelling (LaMEM.jl) to examine how syn-collisional breakoff of the Tethyan slab and the subduction of the leading margin of Indian continental lithosphere influence Gangdese topography. Our results show that a ~25-km-thick subducted Indian continental crust beneath the Gangdese arc, reaching a UHP condition, can provide additional buoyancy to rapidly uplift Gangdese’s elevation to ~3.5 km within 5 Myr after plate contact. The magnitude of surface uplift is positively correlated with the thickness of the leading margin of the subducted Indian crust. Slab breakoff, despite occurring at a relatively shallow depth (80 to 150 km), has minor and transient effects on Gangdese’s elevation. Our study shows that both geochemical proxies-based crustal thickness and stable isotope-based paleo-altimetry could be correct given that the former captures the overriding crust thickness, while the latter reflects total elevation supported by deeper buoyancy. We suggest that during the subduction-collision transition, crustal-scale isostasy with an assumed compensation depth at the overriding plate’s Moho depth can be problematic when converting Gangdese’s crustal thickness to elevation. Instead, a deeper compensation depth (e.g., at 200 km) is required to correctly calculate the isostatic elevation incorporating the buoyancy from the subducted Indian crust.
Geological Society of America Abstracts with Programs. Vol. 57, No. 6
doi: 10.1130/abs/2025AM-412883
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