摘要
通过对保山地块黑牛凹金矿区内辉绿玢岩进行LA-ICP-MS原位微区锆石U-Pb定年和岩石地球化学特征分析,获得了辉绿玢岩的成岩年龄为(212.0±4.9)Ma,这一时限与核桃坪矿区内辉绿玢岩成岩时限(195.0±5.3)Ma,以及金厂河矿区辉绿玢岩成岩时限(217.3±5.8)Ma具有一致性,均属晚三叠世。黑牛凹辉绿玢岩具有低SiO2、低MgO及高钾特征,属于钾玄系列。微量元素具有富集轻稀土元素(LREE)、大离子亲石元素(LILE)及亏损高场强元素(HFSE)的特征,暗示其源区为岩石圈地幔。岩石中的Cr、Ni元素含量明显比原始玄武岩浆低,表明岩浆可能经历了橄榄石和辉石的结晶分离作用。Nb、Ta元素具明显负异常,暗示在岩浆上升侵位过程中受到了地壳物质的混染。黑牛凹辉绿玢岩形成的构造背景与区域内金厂河辉绿岩、核桃坪辉绿岩一致,均为板内拉张环境,这可能与古特提斯洋闭合导致保山地块因碰撞而发生的内部拉张、伸展活动有关。
The special geotectonic location of Baoshan block makes it undergo a series of Tethys evolutionary activities with frequent regional tectonic-magmatic activities.Granite is developed from Paleozoic to Cenozoic.In addition,a large number of basic intrusive rocks occurring as dikes and dikes are also developed in the region.Previous research and analysis of granite in the region is relatively systematic,but the study and analysis of basic rocks in the region,especially basic dikes commonly developed in typical polymetallic ore areas in the ore concentration area,is relatively weak.Previous studies and analyses only the chronology of diabase and its relationship with mineralization in the Hetaoping lead-zinc polymetallic ore area.The study and analysis of the petrogenesis of basic rocks is almost blank.Therefore,the diabase porphyrite in typical boreholes of Heiniu’ao gold deposit has been systematically analyzed in terms of petrochemical characteristics and zircon U-Pb dating in LA-ICP-MS in situ.The main elements of Heiniu’ao diabase porphyry are characterized by low SiO2,low TiO2,high Al2O3,low MgO,high FeOT and low K2O,belonging to the shoshonite series.Trace and rare earth elements are characterized by enrichment of light rare earth elements(LREE)and large ion lithophile elements(LILE)and depletion of high field strength elements(HFSE),suggesting that their source areas are lithospheric mantle.The content of Cr and Ni in the rocks is obviously lower than that in the original basalt magma,indicating that the magma may have undergone the crystallization separation of olivine and pyroxene.The obvious negative anomalies of Nb and Ta suggest that they were contaminated by crustal materials during the process of magma emplacement.The tectonic environment is consistent with the tectonic background of Jinchanghe diabase and Hetaoping diabase,which are intraplate extensional environments.The diagenetic age of the diabase porphyrite obtained in the mining area is(212.0±4.9)Ma,which is similar to the diagenetic age o
作者
罗应
卢映祥
刘学龙
薛顺荣
王帅帅
李振焕
张昌振
陈建航
LUO Ying;LU Yingxiang;LIU Xuelong;XUE Shunrong;WANG Shuaishuai;LI Zhenhuan;ZHANG Changzhen;CHEN Jianhang(Faculty of Land Resource Engineering,Kunming University of Science and Technology,Kunming 650093,Yunnan,China;Key Laboratory of Sanjiang Mineralization and Resource Exploration and Utilization,Ministry of Land and Resources,Kunming 650051,Yunnan,China)
出处
《黄金科学技术》
CSCD
2020年第1期1-11,共11页
Gold Science and Technology
基金
云南省科学技术奖“杰出贡献奖”项目“西南三江复合成矿作用疑难问题研究”(编号：2017001)
云南省基础研究计划项目“滇西北中甸铜厂沟燕山期斑岩型Mo-Cu矿床热液蚀变分带与成矿流体研究”(编号：2019FB062)
云南省万人计划“青年拔尖人才”专项(编号：20190028)
昆明理工大学重点学科建设经费项目“地质资源与地质工程(省级一流学科)”(编号：1407839305)联合资助
关键词
辉绿玢岩
锆石U-Pb定年
地球化学特征
晚三叠世
板内拉张环境
滇西
diabase porphyrite
zircon U-Pb dating
geochemistry
Late-Triassic
intraplate extensional environment
Western Yunnan
