Formation of the Shuixie Cu–Co ore district in response to structural reactivation during block rotation in the southeastern Tibetan Plateau

Abstract

The southeastern Tibetan Plateau formed by the oblique indentation of India into Eurasia. The concurrent formation of major ore deposits provides an opportunity to test how structural reactivation and block rotation may have controlled mineralisation. A systematic structural analysis and low-temperature thermochronological data have been combined to establish the structural evolution and controls on emplacement of ore bodies in the Shuixie Cu–Co ore district within the southeastern Tibetan Plateau. Three deformation events (D₁ to D₃) were identified based on overprinting structural elements, with mineralization occurring during D₂. Zircon and apatite (U–Th)/He thermochronological data demonstrate that the Shuixie Cu–Co ore district was formed at approximately 28–20 Ma. The ore-controlling structures are sinistral strike-slip faults that were activated along pre-existing cleavage planes. Breccia- and vein-type ores filled the space in simple shear and transtensional zones, respectively, along the sinistral strike-slip faults. Block rotation and relatively constant stress within the oblique orogen, triggered the opening and closure of ore-controlling structures reactivated along cleavage in the Shuixie district. The genetic links between block rotation, structural reactivation, and mineralization within the oblique collisional belt could be unraveled by combining structural analysis with low-temperature thermochronology.