LA-MC-ICP-MS U-Pb dating of cassiterite from the Jianfengpo Sn deposit in the Pengshan Sn-polymetallic ore field, Jiangxi Province and its geological significance

The Pengshan Sn-polymetallic orefield in De' an County, Jiangxi Province lies in the east part of Qinzhou-Hangzhou metallogenic belt which belongs to Yangtze Block. There have no report on the precise dating for the tin-polymetallic mineralization in this district before. Here we report for the first time in-situ U-Pb data on cassiterite obtained by LA-MC-ICP-MS from the Jiangfengpo tin deposit. In this study, we obtain a Ph-206/Ph-207-U-238/(207) Pb isochron age of 129.7 +/- 2.5Ma (N = 31, MSWD = 5. 5) and a Pb-207/Pb-206-U-238/Pb-206 concordia age of 128.3 +/- 2.5Ma ( N = 31, MSWD =7. 6) for the cassiterite samples. These ages indicate that the Sn-mineralization took place during Early Cretaceous, which are corresponding to the Later Yanshanian magmatic event in the Pengshan area. The close temporal and spatial link between the pluton's emplacement and tin mineralization suggest that the Later Yanshanian magmatic hydrothermal events were the key factor for the formation of the Sn polymetallic deposits in the Pengshan area. The regional geochronological data show that Sn-W mineralization took place during Early Cretaceous (146 similar to 124Ma) in the southeastern margin of the Yangtze Block (SMYB), which are similar to the Cu-polymetallic mineralization ages of the Jiurui-E' dongnan ore districts on the Middle-Lower Yangtze River Metallogenic Belt (MLYRMB) but different to the Sn-W mineralization ages of the Later Jurassic (160 similar to 150Ma) in Nanling area and the Later Cretaceous (98 similar to 76Ma) in the southeastern Yuannan and northwestern Guangxi area in South China. The available data suggested that the Sn-W mineralization in the SMYB, which was under different tectonic setting from that in Nanling and southeastern Yuannan and northwestern Guangxi area, may be influenced by the tectono- magmatism of the MLYRMB.