PRECISE AGE CONSTRAINTS FOR THE WOXI Au-Sb-W DEPOSIT, SOUTH CHINA

Abstract

Abstract Accurately resolving the timing of formation of Au-Sb-W deposits hosted in metasedimentary rocks has been the aim of extensive research but has also led to controversy. In this study, we present high-precision laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb dating of hydrothermal apatite and wolframite from the Woxi Au-Sb-W deposit, South China. Veins are dominated by quartz, native gold, auriferous pyrite, arsenopyrite, stibnite, scheelite, wolframite, and apatite. Wolframite grains yield U-Pb ages of 144.8 ± 1.5 Ma (2s) and 140.3 ± 1.4 Ma, which overlap with apatite ages of 148.7 ± 2.4 to 144.1 ± 2.7 Ma. Collectively, the new data confirm the Woxi deposit is solely Late Jurassic-Early Cretaceous in age, despite previous dates using other isotopic systems that were as old as Silurian. Our compilation of geologic characteristics, tectonic setting, and geochronology of Au-Sb-W deposits from the western part of the Jiangnan belt shows there were two episodes of Au-Sb-W metallogenesis. These events in the Late Triassic and Late Jurassic-Early Cretaceous related to an extensional setting following Triassic intracontinental orogeny and to Late Jurassic-Early Cretaceous extension associated with Izanagi plate rollback, respectively.