Massive crustal carbon mobilization and emission driven by India underthrusting Asia
Wei Liu, Maoliang Zhang, Yi Liu, Lifeng Cui, Yuji Sano, Xiaocheng Zhou, Ying Li, Lihong Zhang, Yunchao Lang, Cong‐Qiang Liu, Sheng Xu
Abstract
Abstract The active Himalayan-Tibetan orogen, where India underthrusts into Asia, is an important geological source of carbon dioxide (CO 2 ) emission into Earth’s atmosphere. However, the extent to which Indian underthrusting could stimulate the mobilization of deeply-sourced carbon and its subsequent emission remains unknown. Here, we use a combination of field observations coupled with in-situ CO 2 flux measurements and helium and carbon isotopic data, to study the controls on CO 2 origins and fluxes in a 400-kilometre-long rift transecting northern Himalaya and southern Tibet. High diffuse CO 2 fluxes sustained by pure crustal fluids are confined to rift segments in the northern Himalaya, while toward southern Tibet, CO 2 fluxes become lower but mantle fluid inputs are identified. Such rift-related CO 2 degassing profile suggests metamorphic decarbonation and release of carbon-bearing fluids enhanced by the underthrusting Indian lower crust, agreeing well with Himalayan metamorphism and orogen-parallel lithospheric extension. Deep CO 2 fluxes from extensional tectonics in northern Himalaya and southern Tibet, primarily of crustal origins, are comparable to mantle CO 2 fluxes from global mid-ocean ridges. Our findings demonstrate that geophysical and geo-tectonic responses to continental underthrusting could facilitate massive crustal carbon mobilization and emission, making active collisional orogens globally important carbon sources.