新疆博格达东缘色皮口一带辉绿岩地球化学、锆石U-Pb年龄及地质意义  

Studies on the Geochemistry,Zircon U-Pb Age and Geological Significance of Diabase in the Sepikou Region,Eastern Bogda,XinJiang

作　　者：高景刚[1,2] 李文渊[2] 郭新成[3] 周义[1] 刘建朝[1] 范庭宾[3] 周汝洪[4] 

机构地区：[1]长安大学西部矿产资源与地质工程教育部重点实验室,陕西西安710054 [2]西安地质矿产研究所,陕西西安710054 [3]新疆维吾尔自治区地质矿产勘查开发局第十一地质大队,新疆昌吉833000 [4]新疆维吾尔自治区地质矿产勘查开发局,新疆乌鲁木齐810000

出　　处：《新疆地质》2013年第2期117-123,共7页Xinjiang Geology

基　　金：新疆维吾尔自治区1:5万区域地质矿产调查项目(XJQDZ2008-05);中国地质调查局项目(1212011121092);中央高校基本科研业务费专项资金(CHD2010JC128);长安大学基础研究支持计划专项基金联合资助

摘　　要：博格达造山带内出露的晚石炭世辉绿岩,为研究博格达裂谷演化末期地球动力学背景提供了重要信息.色皮口地区辉绿岩主量元素以低TiO2、较高Al2O3、较低MgO、贫P2O5,较低的K2O/Na2O比值（0.12-0.53）,ΣREE较高,LREE/HREE为2.45-3.56,铕负异常不明显（δEu=0.82-1.02）等为特征.与原始地幔相比,其不相容元素K,Rb, U,Ba富集,高场强元素Nb,Ta,Zr,Hf无富集,Ti亏损不明显,Nb,Ta,Th表现为明显负异常.U富集可能指示与地壳物质的加入有关,较低的Nb/Zr比值（0.02-0.06）,暗示岩浆源区可能为受地壳混染的亏损地幔.辉绿岩LA-ICP-MS锆石U-Pb定年结果为（300.5±1.7） Ma（MSWD=2.3,Th/U比值为0.36-1.3）,为晚石炭世晚期,代表了博格达裂谷闭合后地球动力学环境由挤压变为拉张的转折期.The Late Carboniferous Diabase in bogda orogenic belt provides important information on the bogda rift tec-tonic evolution.The geochemistry of the major is characterized by low contents of TiO2（0.81%-2.1%）,MgO（5.83%-10.48%）, K2O and P2O5, high Al2O3 and low K2O/Na2O ration.Meanwhile,it is showing that the diabase is enrichment in light rare earth elements with abundance rare earth elements,LREE/HREE ration contents between 2.45 and 3.56,the dia-base exhibits slightly negative Eu anomalies （δEu=0.82-1.02）.Comparing with the primitive mantle,they are enriched in the large-iron-lithophile elements（such as K,Rb,U,Ba ） and depletion of high-field-strength element（such as Nb and Ta） and Th. U enrichment may be indicating contamination by crustal materials,lower Nb/Zr ration （0.02-0.06）.The above characteristics indicate that magma source are originated from depleted mantle of contamination by crustal materi-als.Using LA-ICP-MS method of U-Pb age dating,it is the 300.5±1.7Ma（MSWD=2.3,Th/U=0.36-1.33）that represents the crystallized age of the diabase.It represents the important conversion from compression to extension in Geodynamics.

关 键 词：新疆 博格达 锆石U—Pb定年 地球化学 辉绿岩 

分 类 号：P597.3[天文地球—地球化学]