塔里木板块东北部笔架山东基性-超基性岩体地球化学特征与岩石成因  

Geochemical Characters and Petrogenesis of the Bijiashandong Basic-Ultrabasic Intrusion,NE Tarim Plate

作　　者：夏昭德[1] 夏明哲[1,2] 王垚[1] 姜常义[1,2] 凌锦兰[1] 

机构地区：[1]长安大学地球科学与资源学院,西安710054 [2]长安大学西部矿产资源与地质工程教育部重点实验室,西安710054

出　　处：《地质科技情报》2012年第2期1-8,共8页Geological Science and Technology Information

基　　金：国家自然基金项目(40872070);中国地质调查局地质调查项目(1212011120498);中央高校基本科研业务费专项资金(CHD2010ZY008)

摘　　要：笔架山东基性-超基性岩体位于塔里木板块东北部的新疆北山地区,是笔架山岩带中最东边的一个岩体,岩体形态为椭圆状,出露面积约5km2。由含长单辉橄榄岩、橄榄辉长岩、含橄辉长岩、辉长岩以及辉绿岩组成。含橄榄石较多的岩石属拉斑玄武岩系列,而辉长岩属钙碱性系列。岩相学、岩石化学和微量元素地球化学特征表明岩浆演化过程中经历了橄榄石、辉石、斜长石的分离结晶作用。Nd、Sr、Pb同位素组成和岩石地球化学特征反映出岩浆与围岩之间存在物质交换。笔架山东岩体的岩浆源区为OIB型地幔源区,原生岩浆为高镁拉斑玄武岩浆[w(MgO)=11.2%],这些性质与塔里木板块东北部其他基性-超基性岩体的特征相似,表明塔里木板块东北部二叠纪基性-超基性岩体的源区主要为OIB型地幔,可能与地幔柱有关。The Bijiashandong basic-ultrabasic intrusion,located in the Beishan area in Xinjiang,northeastern Tarim plate,is the most eastern intrusion of Bijiashan belts.The intrusion is oval-shaped and outcrops about 5km2.The main kinds of the rocks are feldspathic wehrlite,olivine gabbro,olivine-bearing gabbro,gabbro and diabase.The rocks containing olivine are tholeiitic series and the gabbros are calc-alkalic series.Petrography,petrochemistry and geochemistry characters indicate the fractional crystallization of olivine,pyroxene and plagioclase in magma evolution.Nd,Sr,Pb isotopic compositions and lithogeochemical characteristics imply the exchange of material between the magma and the wall-rocks.It is proved that the primitive magma of Bijiashandong intrusion was high-Mg tholeiitic magma（MgO=11.2%） and derived from an OIB-like mantle source,which are similar to other basic-ultrabasic intrusions of Permain in the northeastern Tarim plate,indicating that these intrusions were mainly derived from an OIB-like mantle source and could be related to mantle plume.

关 键 词：笔架山东岩体 同化混染 分离结晶 岩浆源区 新疆 

分 类 号：P595[天文地球—地球化学] P581[天文地球—地质学]