云南蒙自白牛厂银多金属矿区断裂带方解石脉原位U-Pb年代学  

In-situ U-Pb dating of fault-zone calcite vein in the Mengzi Bainiuchang silver polymetallic deposit,Yunnan province

作　　者：夏庆元 范茂煌 李鑫 XIA Qingyuan;FAN Maohuang;LI Xin(Faculty of Land Resources Engineering,Kunming University of Science and Technology,Kunming 650032,China;Team 306,Yunnan Nonferrous Geology Bureau,Kunming 650217,China)

机构地区：[1]昆明理工大学国土资源工程学院,昆明650032 [2]云南省有色地质局三○六队,昆明650217

出　　处：《有色金属（矿山部分）》2023年第2期131-140,共10页NONFERROUS METALS(Mining Section）

基　　金：国家自然科学基金资助项目(41373050)。

摘　　要：形成于浅部地壳的脆性构造通常记录了地壳浅层构造变形过程,对其精确的年代学限定一直是构造地质研究的难点。近年来,方解石U-Pb定年技术在地质年代学领域迅速发展,通过脆性构造变形同构造方解石矿脉的U-Pb定年可以用于精确限定脆性构造变形事件的时代。为了限定区域构造变形历史,针对蒙自白牛厂内的对门山矿段的同构造方解石脉进行了LA-ICP-MS U-Pb年代学研究,并获得了两期可靠同位素年龄,分别为(80±20)Ma和(36±7.8)Ma,这两期年龄是对该矿区断裂带年龄的首次报道,且与区域上的构造事件和岩浆事件基本吻合。结合前人的研究表明,该区域燕山期和喜山期分别存在着至少一期断裂构造运动,其中(80±20)Ma在拉张环境下产生的断层及破碎带是成矿流体运移富集的有利场所。Brittle structures are formed in the shallow crust,which usually records the shallow deformation processes.Direct dating of brittle structures is challenging for structural geology research.In recent years,calcite U-Pb dating technology has developed rapidly in the field of geochronology,and the U-Pb dating of brittle tectonic deformation and structural calcite veins can be used to accurately define the era of brittle tectonic deformation events.In this study,we performed in-situ LA-ICP-MS U-Pb dating of the syntectonic calcite veins collected from the Duimenshan section of the Mengzi Bainiuchang,for constrained the history of regional tectonic deformation.Two reliable in-situ U-Pb ages of two calcite samples were obtained,they are(80±20)Ma and(36±7.8)Ma,which is consistent with the tectonic events and magmatic events in the region.Integrated with previously reported results,we propose that there is at least one phase of fault tectonic movement in the Yanshan period and Xishan period in this region,and the faults and fracture zones generated by(80±20)Ma in a tensile environment are favorable places for the transport and enrichment of mineralizing fluids.

关 键 词：断裂带 方解石U-Pb测年 控矿构造 滇东南 蒙自白牛厂 

分 类 号：TD15[矿业工程—矿山地质测量]