广东云浮高枨银铅锌多金属矿区成矿地质特征及成岩时代研究

高枨银铅锌多金属矿床是南岭成矿带中新探明的典型构造蚀变岩型矿床之一。矿床控制规模已达中型以上,但研究程度低,成因认识模糊,影响找矿进展。本文根据脉状矿体稳定延伸、主矿脉产于中酸性岩体中、部分矿脉穿切白垩系红层及老变质岩系的宏观地质特征,认为该多金属矿属岩浆期后热液成因,成矿作用发生在晚白垩世至古近纪。通过LA-ICP-MS锆石U-Pb法确定地表含矿岩体的年龄为438.7±0.8Ma,属于加里东期。因此,地表含矿花岗岩体作为围岩,其形成时代明显早于成矿期,推测矿区深部存在隐伏岩体,隐伏岩体是成矿的主导因素。这一成果为今后找矿方向的调整提供了重要依据。

Research on the Geological Features and Forming Age of Hostrock of the Gaocheng Lead-Zinc Deposit, Yunfu, Guangdong

The newly discovered Gaocheng silver-lead-zinc polymetallic deposit is one of typical structural controlled deposits hosted within altered rocks in the Nanling metallogenic belt,South China.Even the scale of the deposit is up to medium-size,few research works have been done on it,and consequently the mis-understanding for the ore genesis slowdown the prospecting program.Based on the general features of this ore deposit,including the continuity of veins extending from granitic rock to metamorphic rocks to sedimentary rocks,especially parts of the main veins cutting across the Cretaceous red-strata,this paper takes the Gaocheng polymetallic deposit as a post-magmatic hydrothermal deposit formed at the Late Cretaceous to Paleogene stage.The age of ore-hosted rock was dated to be 438.7±0.8 Ma,using LA-ICP-MS zircon U-Pb method.Thus,the outcropped granite acted as hostrock for the Gaocheng deposit,with its forming age earlier than mineralization stage.Besides,it is possible for un-drilled granite of Late Mesozoic to Early Cenozoic stage existed bellow the Gaocheng deposit,which might be genetically related to the Ag-Pb-Zn deposit and supply ore-forming materials for the latter.This achievement not only provides important evidence for the study of ore deposits,but also guide for future prospecting.