The Discovery of Late Jurassic Volcanic Rocks in Lengshuikeng, Jiangxi and Their Geological Significance

The Jiangxi Lengshuikeng ore field, characterized as porphyry deposits and volcanic sedimentary hydrothermal reworking deposits, is one of the major Ag-Pb-Zn ore concentration areas in Wuyi Mountain area. There has been much research carried out on mineralization, the metallogenic model, and ore-controlling structure of the Lengshuikeng deposit. However, it is still unclear about the relationship of different geological bodies with mineralization and magmatism. In this paper, a description of a zircon LA-ICP-MS U-Pb geochronology approach and its implementation on the volcanic rock of Daguding Formation and ore-bearing granite porphyry is given. The crystal tuffs from the top and bottom of Daguding Formation and ore bearing granite porphyry yield U-Pb age of 161.3±1.3 Ma, 160.75±0.96 Ma and 168.09±0.80 Ma, respectively. These results indicate that there were three stages of volcano-magmatic activities in the Lengshuikeng ore field with ages of 164-170 Ma, 157-161 Ma, and 140-146 Ma, respectively. The 157-161 Ma is the main metallogenic epoch of the volcanic sedimentary-hydrothermal reworking type deposit and porphyry type deposit. The discovery of the late Jurassic volcanic rocks in Lengshuikeng provides the important geological evidence for the detailed study of the Mesozoic tectonic regime transition in South China.