诸广山南部高坪地区细粒花岗岩LA-ICP-MS锆石U-Pb年龄及其地质意义

摘要

诸广山南部高坪地区钻探工程揭露到较多细粒花岗岩岩脉,部分岩脉与矿体空间关系密切.本文利用LA-ICP-MS锆石U-Pb定年法测得区内两组细粒花岗岩年龄分别为252.9 ±1.9 Ma(MSWD=1.8)和244±2 Ma(MSWD=1.4).结合细粒花岗岩中晶质铀矿U-Pb定年结果,证实其形成于印支期.本文结合粤北地区铀成矿规律及区域铀成矿特征,对高坪地区铀成矿潜力及找矿方向进行初步探讨,认为:①印支期,诸广山南部先后广泛侵入粗粒斑状黑云母花岗岩与细粒花岗岩,其中细粒花岗岩多沿断裂发育;②至燕山晚期,沿断裂侵入基性脉岩;③高坪地区细粒花岗岩与基性脉岩叠合部位为铀成矿的有利空间.%Recent prospecting have revealed that lots of fine-grained granitic dikes occurred in Gaoping area,South Zhuguang Mountains,and some of them are spatially related with U orebodies.Two groups of ages which including 252.9 ± 1.9 Ma and 244 ± 2 Ma have been detected though LA-ICP-MS U-Pb Dating of zircon,and suggested that the fine-grained granites emplaced during Indonisian,with combination of U-Pb dating of uraninite.With consideration of regional uranium mineralization regularity in North Guangdong and regional uranium metallogenic features,this paper proposed that (1) during Indonisian,significant volumes of granites which could be divided into two stages that including coarse-grained (Early) and fine-grained granites (Later) formed in South Zhuguang Mountains,and the later one mainly emplaced along regional faults;(2) during Yanshanian,mafic dikes emplaced along faults;(3) the location that later mafic dikes superimposed on earlier granitic dikes are the favorable space for later uranium mineralization.