广东阳春锡山钨锡矿床成岩成矿年代学研究

Diagenetic and Metallogenic Geochronlogy Study of the Xishan W-Sn Ore Deposit in Yangchuang of Guangdong Province

为了精确厘定锡山钨锡矿床成岩成矿时代,本文分别对锡山岩体斑状二长花岗岩和矿体开展了锆石LA-ICP-MS U-Pb和石英Rb-Sr年代学研究,获得的锆石U-Pb年龄为103±3Ma,石英矿物Rb-Sr等时线年龄为94±12Ma,两者在测定误差内一致,表明锡山岩体晚阶段形成的花岗岩在时间和空间上与成矿作用有明显的耦合关系,其成岩成矿作用发生在早白垩世晚期。锡山成岩成矿的动力学背景应与早白垩世晚期南岭地区的岩石圈伸展拉张引发的大规模岩浆活动有关。

This study carries out study of zircon U Pb dating on quartz samples from porphyritic monzonitic granite and ore body in the Xishan block using in LA-ICP-MS and Rb Sr dating so to determine the formation time of Xishan W-Sn deposit and the wall rocks. The yielded zircon U-Pb age is 103±3 Ma, and the quartz Rb-Sr iscoehron plots give an age of 94±11 Ma, both ages are within the margin of error. This indicates a coupled relationship in time and space between late stage granite and deposits in the Xishan block, which occurred during Late Cretaceous. The tectonic setting of the Xishan block and deposits may be related to the voluminous magmatic activities caused by the extension of lithosphere in Nanling region in Irate Cretaceous.