广东文光岭铅锌铜多金属矿花岗闪长岩LA-ICP-MS锆石U-Pb定年、地球化学特征及其成因

广东省文光岭矿床是云开地区近年来新发现的铅锌铜多金属矿.以文光岭花岗闪长岩作为研究对象，对其开展了LA-ICP-MS锆石U-Pb同位素定年和地球化学特征研究.获得其锆石206Pb/238U同位素加权平均年龄为165.7±1.9 Ma（n=18，MSWD=3.1）.花岗闪长岩属于准铝质Ⅰ型花岗岩，SiO₂含量在64.11%~66.64%之间，Al₂O₃含量为14.9%~15.57%，MgO含量在1.39%~1.61%之间，K₂O+Na₂O含量介于6.5%~7.21%，K₂O/Na₂O=1.25~2.74，铝饱和指数A/CNK=0.93~1.11.轻、重稀土元素分馏作用明显，（La/Yb）_N=13.03~17.83，具有弱的负铕异常（δEu为0.70~0.88），HFSE和LILE分异明显，富集Rb、Th、U、K等元素，亏损Nb、Ta、P和Ti等元素.结合区内已有资料，认为文光岭铅锌铜多金属矿床的形成与古太平洋板块的俯冲作用密切相关. 

Zircon U-Pb Dating,Geochemistry and Petrogenesis of Granodiorite from Wenguangling Pb-Zn-Cu Polymetallic Deposit in Guangdong Province

The recently discovered Wenguangling deposit is a Pb-Zn-Cu polymetallic deposit, located in the Yunkai area. It was firstly investigated of the granodiorites from the Wenguangling deposit by integrating in situ zircon U-Pb dating and geochemical analysis. Eighteen zircons from sample WGL-02 yield excellently concordant results with a weighted mean 206Pb/238U age of 165.7±1.9 Ma (n=18, MSWD=3.1). The Wenguangling granodiorites belong to metaluminous Ⅰ-type granite. Their SiO₂ and Al₂O₃ contents are 64.11%-66.64% and 14.9%-15.57%, respectively. The MgO contents are between 1.39% and 1.61%. The alkali (K₂O+Na₂O) contents range from 6.5% to 7.21%, with K₂O/Na₂O ratios from 1.25 to 2.74. Their aluminum indexes (A/CNK ratios) are 0.93-1.11. The granodiorites are also characterized by noteworthy fractionation between LREE and HREE ((La/Yb)_N=13.03-17.83), with weak negative Eu anomalies (δEu=0.70-0.88). The trace element analyses show clear fractionation between HFSE and LILE, and the granodiorites are strongly enriched in Rb, Th, U and K but depleted in Nb, Ta, P and Ti. Based on the geochemistry, zircon U-Pb dating of the Wenguangling granodiorite and regional tectonic evolution, it is infered that the formation of the Wenguangling Pb-Zn-Cu polymetallic deposit is closely associated with the subduction of the Paleo-Pacific plate.