新疆博格达东段阿克铁克协山地区辉绿岩岩石地球化学特征及其SHRIMP U-Pb测年意义  

Geochemical Characteristics and SHRIMP U-Pb Age Significance of Diabase in Aketiekexie Moutain Area,East of Bogda,Xinjiang

作　　者：陈邦学 朱志新 周能武 靳刘圆 李平 

机构地区：[1]新疆地矿局第十一地质大队,新疆昌吉831100 [2]新疆地调院,新疆乌鲁木齐830000

出　　处：《西北地质》2015年第3期1-11,共11页Northwestern Geology

基　　金：十二五科技支撑计划重点项目(2011BAB06B04);新疆中亚造山带大陆动力学与成矿预测实验室开放课题(XJDX1102-2011-04)共同资助

摘　　要：通过对阿克铁克协山地区的辉绿岩研究,发现其既具有板内玄武岩的特征(由主量元素特征显示强过铝质,碱性系列),又显示出板块边缘的"假象"特征(主要是由于陆壳物质的混染造成的Nb、Ti等高场强元素的亏损),而且辉绿岩REE分布模式明显以Nd/Pm、Gd、Ho/Er为分界点,形成4条曲线,明显具有"MM"型,显示出了良好的四分组效应或四重效应。阿克铁克协山地区的辉绿岩SHRIMP U-Pb测年,显示具有2期年龄,上交点年龄为(408±10)Ma,时间为早泥盆世,代表岩浆的结晶年龄;下交点年龄为(301±10)Ma,应为晚石炭世一次热构造事件。结合前人研究,认为博格达造山带属于裂谷而并非岛弧环境,博格达裂谷演化始于东段,而且东段早于西段,东段的演化是以早泥盆世的辉绿岩岩浆活动为标志。Based on the study of diabase in Aketiekexie Mountain region, intraplate basalt characteristics（strong peraluminous and alkaline series）, and illusion of the plate boundary（mainly caused by contamination of continental crustal material loss of the Nb, Ti high field strength elements） were identified. In addition, the REE distribution patterns of the diabase were four MM - type curves divided by Nd/Pm, Gd and Ho/Er, showing tetrad effect or quadruple effect. SHRIMP U-Pb dating results display two ages, which are upper intersection point age of （408± 10）Ma in early Devonian, representing magma crystallization periods, and lower intersection age of （301± 10）Ma, coinciding the thermal tectonic event in late Carboniferous. Combining with previous researches, Bogda orogenic belt belongs to rift tectonic setting rather than island arc environment. Bogda rift evolution first begins in the east section and the evolution is marked by diabase magma activities in early Devonian.

关 键 词：地球化学 辉绿岩 U—Pb测年 博格达 

分 类 号：P597[天文地球—地球化学]