摘要
大坪金矿是哀牢山-红河韧性剪切带南段最重要的大型金矿床之一,由于其成矿时代和构造背景一直存在争议,不利于带内金矿床成矿模型的建立和进一步找矿勘探。本文利用LA-ICP-MS对矿区内含金石英脉中热液锆石、闪长岩和花岗闪长岩脉中岩浆锆石开展了U-Pb年代学研究,获得热液锆石U-Pb年龄为760±10 Ma,表明大坪金矿区可能存在新元古代金矿化事件;获得闪长岩和花岗闪长岩脉的锆石U-Pb年龄分别为773±9 Ma和766±9 Ma,与区域上Rodinia超大陆裂解和哀牢山地区的晋宁-澄江期大规模火山-岩浆活动事件时代一致。热液锆石与闪长岩、花岗闪长岩脉具有相似的Hf同位素组成特征和在误差范围内一致的年龄,表明新元古代金矿化事件可能与闪长岩和花岗闪长岩脉的侵入有密切的成因联系。本文新元古代成矿事件的厘定,结合前人的新生代始新世—渐新世为大坪金矿主要成矿时期的研究结果,表明大坪金矿可能是新元古代和新生代不同岩浆-构造-热液事件叠加成矿作用的产物。
The Daping Au deposit is one of the most important large-sized gold deposits in the south of the Ailao Mountain-Honghe River ductile shear zone.Due to the disputes on its mineralization timing and tectonic setting,it’s difficult to establish the metallogenic model as well as further explore and exploit gold deposits in this belt.In this paper,LA-ICP-MS was used to study the U-Pb geochronology of hydrothermal zircon from Au-bearing quartz veins and magmatic zircon from diorite and granodiorite vein in the Daping Au deposit.The result shows that the age of hydrothermal zircon is 760±10 Ma,suggesting that there was a Neoproterozoic mineralization event for the Daping gold deposit.The magmatic zircons from the diorite and granodiorite vein yielded ages of 773±9 Ma and766±9 Ma,respectively.These results coincide with the breakup of the zircons from the diorite and granodiorite veins.Therefore,combined with their consistent ages within the error range,the authors hold that the Neoproterozoic gold mineralization event might have been Rodinia supercontinent and the Jinning-Chengjiang large-scaled volcanic-magmatic event in the Ailao Mountain area.The hydrothermal zircons have similar Hf isotopic composition to those of related intrusions of diorite and granodiorite.Although the Eocene-Oligocene was thought to be a main mineralization period for the Daping gold deposit in previous literature,the authors consider that the Daping gold deposit probably resulted from superimposed mineralization from the Neoproterozoic and Cenozoic magmatic-tectonichydrothermal events,as shown by the determination of the Neoproterozoic mineralization event in this study.
作者
曹原
何小虎
谈树成
杨建宇
刘沛颖
CAO Yuan;HE Xiao-hu;TAN Shu-cheng;YANG Jian-yu;LIU Pei-ying(College of Earth Science,Yunnan University,Kunming 650091,China;Key Laboratory of Critical Minerals Metallogeny in Universities of Yunnan Province,Kunming 650091,China;Yunnan Hualian Zine&Indium Stock Co..Ltd.,Wenshan 663701,China)
出处
《岩石矿物学杂志》
CAS
CSCD
北大核心
2021年第2期411-428,共18页
Acta Petrologica et Mineralogica
基金
国家自然科学基金项目(41702084)
云南省教育厅研究科学研究基金项目(C176240111)。
