Hydrothermal Degassing Through the Karakoram Fault, Western Tibet: Insights Into Active Deformation Driven by Continental Strike‐Slip Faulting
Maoliang Zhang, Xiangang Xie, Wei Liu, Yi Liu, Linan Wang, Yuji Sano, Yunchao Lang, Cong‐Qiang Liu, Sheng Xu
Abstract
Abstract The Karakoram fault (KKF) is an important strike‐slip boundary for accommodating deformation following the India‐Asia collision. However, whether the deformation is confined to the crust or whether it extends into the mantle remains highly debated. Here, we show that the KKF is overwhelmingly dominated by crustal degassing related to a 4 He‐ and CO 2 ‐rich fluid reservoir (for example, He contents up to ∼1.0–1.6 vol.%; 3 He/ 4 He = 0.027 ± 0.013 R A (1 σ , n = 47); CO 2 /N 2 up to 3.7–57.8). Crustal‐scale active deformation driven by strike‐slip faulting could mobilize 4 He and CO 2 from the fault zone rocks, which subsequently accumulate in the hydrothermal system. The KKF may have limited fluid connections to the mantle, and if any, the accumulated crustal fluids would efficiently dilute the uprising mantle fluids. In both cases, crustal deformation is evidently the first‐order response to strike‐slip faulting.