Comparison of the exhumed history and magnitude between Jiaojia and Linglong goldfields in the Jiaodong gold Province, North China: Constraints from zircon and apatite (U-Th)/He data

Abstract

The northwestern part of the Jiaodong Peninsular is the most important gold producer in China. Recently, the discovery of gold mineralization at a depth of 3,000 m below the surface in the region has generated a great interest for profound prospecting potential among the explorers. However, the maximum exploration depth and the potential of different goldfields have yet to be clarified. This work presents two low-temperature thermochronological datasets of zircon/apatite (U-Th)/He (ZHe/AHe) data for two ∼ 2,000-m-deep vertical boreholes from the Jiaojia and Linglong goldfields in an attempt to constrain the exhumation history and provide new orientation for exploration strategies in the NW Jiaodong Peninsula. The ZHe and AHe ages are in the range of 120–60 Ma and 70–10 Ma, respectively, and suggest that the NW Jiaodong area has been under a slow exhumation process since the gold mineralization. However, ZHe and AHe ages, together with QTQt thermal modeling, revealed three relatively rapid cooling/exhumation episodes at ∼ 110 – 95 Ma, 70 – 60 Ma and 45–40 Ma or 25–20 Ma. The former two episodes are almost synchronous and can be attributed to two plate-scale collision events, whereas the last episode is asynchronous and can be attributed to local structural movements among goldfields. Our data revealed that the tectonic exhumation and cooling over the period of ∼ 110 – 95 Ma had a significant impact on the ZHe age components and its spatial distribution in the NW Jiaodong area, and the last local structural movements that occurred during the Cenozoic had an intensive impact on the AHe ages and the levels of exhumation among goldfields. Finally, this study suggests economic exploration potential at a ∼ 3.5 – 4 km depth for the Jiaojia and Sanshandao goldfields and ∼ 2.5 – 3 km for the Linglong goldfield.