云南省武定县迤纳厂铁铜矿区古元古代辉绿岩锆石的U-Pb年龄及其地质意义  

Zircon U-Pb Age of the Paleoproterozoic Diabase from the Yinachang Iron-copper Deposit,Yunan Province,and its Geological Implication

作　　者：郭阳[1] 王生伟[1] 孙晓明[2,3,4] 廖震文[1] 王子正[1] 周邦国[1] 杨斌[1] 

机构地区：[1]中国地质调查局,成都地质调查中心,四川成都610081 [2]中山大学海洋学院,广东广州510275 [3]中山大学地球科学系,广东广州510275 [4]广东省海洋资源与近岸工程重点实验室,广东广州510275

出　　处：《大地构造与成矿学》2014年第1期208-215,共8页Geotectonica et Metallogenia

基　　金：国家重点基础研究发展规划(973)项目(编号:2009CB421006);国家自然科学基金(批准号:40830425,U1302233,40173025,40873034,40673045);国土资源大调查(编号:1212010911064,1212011120640,1212010813066)项目联合资助

摘　　要：云南省武定县迤纳厂铁铜矿区广泛出露元古宙辉绿岩体。前人对区内基性岩浆岩研究程度较低,缺乏辉绿岩的形成时代资料。本文报道了区内海孜辉绿岩中锆石的LA-ICP-MS U-Pb年龄,为1728±4 Ma。此年龄与古元古代晚期扬子地台西南缘大规模非造山型岩浆活动及全球性Columbia超级大陆裂解时代高度一致,表明其可能为Columbia超级大陆裂解的产物。辉绿岩与区内铁铜矿床成矿时代大致相当,反映了古元古代晚期扬子地台西南缘大规模的岩浆活动也可能是一次重要的成矿事件,可能为铁、铜成矿作用提供主要的成矿物质来源。武定地区被辉绿岩侵入接触的原"美党组"地层的沉积时代应大于辉绿岩的侵位时代,应划入下元古界汤丹群,是昆阳陆内裂谷拉张以前就已存在的基底地层。There exists a large number of diabase rock bodies at the Yinachang iron-copper deposit in Wuding, central Yunnan Province, southwest China. So far, few research works have been carried out on the mafic rocks within this ore district, thus the age of the diabases remains poorly understood. In this paper, we report the zircon U-Pb age of the Haizi diabase obtained by LA-ICP-MS method, and the weighted mean 206Pb/238U age is 1728±4 Ma （MSWD=1.8, n=11）. The age of the diabase in the Wuding area is consistent with the contemporary magmatism in the southwestern Yangtze Block, as well as the breakup of the Columbia supercontinent. Therefore, it is suggested that these diabases formed in response to the global breakup event of the Columbia supercontinent. Moreover, the age of the Haizi diabase is roughly comparable with metallogenetic epoch of the typical iron-copper deposit, implying the possible metallogenetic significance of Late Paleoproterozoic magmatism in the southwestern Yangtze Block. This large-scale magmatic event might have been the main sources of ore-forming materials, such as Cu and Fe. In addition, the “Meidang Formation”should be older than the diabase that intruded it. Therefore, we propose that the so called“Meidang Formation”, which may be considered as the more ancient basement strata existed before continental extension of the Kunyang rift, should be included in Paleoproterozoic Tangdan Group.

关 键 词：U-PB定年 辉绿岩 迤纳厂铁铜矿床 Columbia超级大陆 昆阳裂谷 昆阳群 武定 

分 类 号：P597[天文地球—地球化学]