广东大宝山多金属矿床花岗岩锆石LA-ICP-MSU-Pb定年及其地质意义

广东大宝山矿床位于南岭花岗岩带中带。它是我国著名的大型多金属矿床，开采历史久远。近年来的研究表明大宝山矿床与成矿作用有关的斑岩体为燕山早期岩浆活动的产物，因而人们较多地关注中生代的岩浆活动，而忽视了对其他时代岩浆活动的研究。本文在前人研究的基础上，利用锆石LA-ICP-MS U-Pb定年方法系统地测试了大宝山多金属矿床多个花岗质岩体和辉绿岩脉的形成时代，研究表明徐屋片理化流纹斑岩年龄为426.9±2.2Ma、九曲岭黑云母花岗闪长斑岩、船肚花岗闪长岩和大宝山花岗闪长斑岩形成时代分别为162.2±0.7Ma、160.2±0.9Ma和161.0±0.9Ma。矿区内两条辉绿岩脉的年龄分别为210.4±1.4Ma和163.9±1.8Ma。这些结果证实大宝山矿区内存在加里东期、印支期和燕山期等多个旋回的岩浆活动，中晚侏罗世铁镁质的岩浆活动可能存在对成矿的贡献。

Zircon LA-ICP-MS U-Pb ages of granites at Dabaoshan polymetallic deposit and its geological significance, Guangdong, South China

Dabaoshan polymetallic deposit is located at the middle part of the Nanling granite belt, South China, which is a famous large deposit with a long history of mining. Much attention has been paid to the Mesozoic magmatism because recent research reveals that Mo(W)-ore related porphyries are the product of Yanshanian magmatism, while little effort has been done on the other stage magmatism. Based on the previous study, zircon LA-ICP-MS U-Pb dating has been conducted on different stage granites and mafic dykes in order to systematically clarify the magmatic activity of the studied area. The weighted average ²⁰⁶Pb/²³⁸U age of Xuwu rhyolitic porphyry is 426.9±2.2Ma, and the weighted average ²⁰⁶Pb/²³⁸U ages are 162.2±0.7Ma, 160.2±0.9Ma and 161.2±0.9Ma for Jiuquling granodiorite porphyry, Chuandu granodiorite and Dabaoshan granodiorite porphyry, respectively. Two mafic dykes recorded two magmatic events of 210.4±1.4Ma and 163.9±1.8Ma, respectively. Therefore, it is proved that the Dabaoshan area has gone through a multiple magmatic activity including Caledonian, Indosinian and Yanshanian. Middle-Late Jurassic mafic magma might have contributed to the Dabaoshan polymetallic mineralization.