Thermochronological constraints on the exhumation history of the Carboniferous Katebasu gold deposit, western Tianshan Gold Belt, NW China

Abstract

The western Tianshan Gold Belt hosts numerous giant and large gold deposits that have been formed during the late Paleozoic amalgamation of the Tianshan orogen. However, little is known about their exhumation histories during the Mesozoic to Cenozoic intracontinental evolution of the orogen. The Carboniferous Katebasu orogenic gold deposit in northwestern China is a new gold discovery within the western Tianshan Gold Belt, and it shares many similarities with other orogenic gold deposits in the belt. In this contribution, new 40Ar/39Ar and (U-Th)/He ages were combined with previous geochronology and numerical modeling to quantify its post-Carboniferous cooling and exhumation history. The results revealed a three-phase cooling history and two phases of post-mineralization exhumation. We suggest that a large volume (∼0.8 km) of the mineralized roof parts of the Katebasu deposit might have been removed during uplift and erosion, whereas significant ore reserves could still exist at depth. The large erosion depth of the Katebasu gold deposit in the Nalati Range of the Chinese western Tianshan also signifies that shallow-emplaced porphyry and epithermal systems that formed prior to Permo-Triassic uplift might have been largely eroded.