黔西普安辉绿岩的年代学、地球化学特征及其地质意义  

GEOCHRONOLOGY,GEOCHEMISTRY AND GEOLOGICAL SIGNIFICANCES OF DIABASE DYKES IN PU′AN,WEST GUIZHOU

作　　者：曾广乾 何良伦 杨坤光[1,3] 

机构地区：[1]中国地质大学(武汉)构造与油气资源教育部重点实验室,湖北武汉430074 [2]贵州省地矿局113地质大队,贵州六盘水553000 [3]中国地质大学地球科学学院,湖北武汉430074

出　　处：《矿物岩石》2014年第4期61-70,共10页Mineralogy and Petrology

基　　金：国家地质调查局"上扬子地块东南缘锰矿成矿地质背景研究"(12120114016701);贵州省地矿厅"贵州区域构造特征;构造演化与矿产空间分布关系研究";国家自然基金"黔东及其邻区早古生代构造变形对华南大陆再造的启示"(41472190)

摘　　要：针对黔西普安铅锌矿区内的辉绿岩脉进行锆石U-Pb年代学与地球化学研究,结果表明其主量元素以高w（TiO2）（4.12%-4.18%）、高w（CaO）（7.46%-8.63%）和低w（MgO）（4.59%-5.02%）、低碱且Na2O〉K2O为特征,ΣREE总量较高,LREE明显富集。与原始地幔相比,明显富集Rb,Ba,Th等大离子亲石元素,而高场强元素（HFSE）Nb,Zr,Hf等略为亏损,并出现K,Sr和P亏损。主量元素特征和微量元素标准化图解显示,普安辉绿岩属于拉斑玄武岩系列,具有洋岛玄武岩（OIB）的特征,与峨眉山玄武岩为同源产物,具有密切的成因关系。微量元素示踪表明,岩浆来源于富集地幔,具有地幔柱成因特征。LA-ICP-MS锆石U-Pb定年结果表明辉绿岩形成年龄为263 Ma±10 Ma,代表了峨眉山地幔柱的启动时间。Zircon U-Pb dating and geochemical analysis was performed on diabase dykes in the Pu′an area,west Guizhou.The major elements of the diabase are characterized by high w（TiO2）（4.12%-4.18%）,high w（CaO）（7.46%-8.63%）,low w（MgO）（4.59%-5.02%）,low alkali and Na2O〉K2O.It is showed that the diabase dykes are enriched in light rare earth elements with abundance rare earth elements.Compared with the primitive mantle,they are distinctly enriched in large-iron-lithophile elements,such as Rb,Ba and Th,slightly depleted of high-field-strength element,Nb,Zr and Hf for instance,and depleted of K,Sr and P.On the basis of major and trace elements patterns,it is demonstrated that the diabase dykes belong to tholeiitic basalt series in lithology and present OIB（Ocean island basalts）features in accordance with Emeishan basalts.Trace elements tracing indicates that the magma originated from an enriched mantle source and possesses origin of mantle plume.LA-ICP-MS method of zircon U-Pb dating shows that the diabase dykes formed at 263 Ma±10 Ma,representing the activating time of Emeishan mantle plume.

关 键 词：峨眉山大火成岩省 辉绿岩 化学成分分析 锆石U-PB年龄 黔西普安 

分 类 号：P588.145[天文地球—岩石学] P595[天文地球—地质学]