广东阳春盆地石菉铜矿床U-Pb年代学及其地质意义

摘要

菉广东阳春石铜矿区位于北东向吴川-四会断裂西南端，对矿床中黄铁(铜)矿化的花岗闪长岩进行锆石 U-Pb 年代学研究，获得了107.2±2.0 Ma的206Pb/238U加权平均年龄，菉与区内石岩体中两件非矿化花岗闪长岩的形成时代(分别为106.7±1.4 Ma和104.1±2.0 Ma)在误差内一致；石菉岩体侵入寒武系、泥盆系和石炭系，在接触带形成的矽卡岩发育程度与矿化程度具有明显的相关性，菉指示了石铜矿床的成矿作用与花岗闪长岩体的侵位密切相关。矿区内分布有燕山早期至燕山晚期的侵入岩，岩性由钾玄质系列过渡到钙碱性系列，反映了区域岩石圈伸展-菉拉张的构造背景。石铜矿床应是区域岩石圈伸展-拉张背景下岩浆作用的产物。%The Shilu copper deposit in Yangchun city, Guangdong province is located at southwest of the NNE-strike Wuchuan-Sihui fault. LA-ICP-MS U-Pb dating of zircons from a pyrite (-chalcopyrite)-mineralized granodiorite sample from the Shilu Copper deposit yielded a weighted mean 206Pb/238U age of 107.2±2.0 Ma, consistent with the results obtained from two non-mineralized granodiorite samples of the Shilu pluton (106.7±1.4 Ma and 104.1±2.0 Ma, respectively) within analytical errors. This indicates that the mineralization was closely related to the emplacement of the granodiorite pluton. Early to Late Yanshanian shoshonitic to calc-alkaline intrusive rocks are widespread in the Shilu area, suggestive of a lithospheric extension tectonic setting. Accordingly, the formation of the Shilu copper deposit might have resulted from the magmatic activity induced by this lithospheric extension.