Hematite (U-Th)/He thermochronometry unveils unique exhumation history: An example from the Dexing porphyry copper deposit, Southern China

Abstract Hematite, commonly found in endogenetic deposits, plays a crucial role in monitoring cooling history temperature variations and can be used to conduct (U-Th)/He dating. Hematite thermochronometry also provides the clearest guide to the timing of the latest thermal evolution path combined with apatite and zircon (U-Th)/He dating. In this study, we established a new method of hematite (U-Th)/He thermochronometry based on an optimized analytical protocol to reveal the evolution of the latest uplift and cooling histroy of the Dexing porphyry copper deposit (DPCD), South China. Two hematite samples were collected from the Tongchang and Fujiawu mines in the DPCD yielded age distributions at 92-11.2 Ma and 112-24 Ma, and gave closure temperatures between 180 and 215 °C based on hematite particle sizes of 88-199 μm. Combined with the published (U-Th)/He thermochronological data on zircon and apatite, this study proposes that the DPCD may have experienced a prolonged temperature derease thermal history. The initial exhumation and uplift were happened at 112 Ma, then a rapid uplift occurred from 11.2 to 8.0 Ma. This study also demonstrates that the hematite (U-Th)/He dating can be effectively applied to reveal the uplift and preservation history of porphyry copper deposits.