新疆西准噶尔达拉布特构造带铝质A型花岗岩的地球化学研究  

Geochemistry of aluminous A-type granites along Darabut tectonic belt in West Junggar, Xinjiang

作　　者：苏玉平[1] 唐红峰[1] 侯广顺[1] 刘丛强[1] 

机构地区：[1]中国科学院地球化学研究所地球深部物质与流体作用地球化学研究室

出　　处：《地球化学》2006年第1期55-67,共13页Geochimica

基　　金：中国科学院西部之光项目(2002年度);国家重点基础研究发展计划项目(2001CB409805)

摘　　要：新疆西准噶尔沿达拉布特构造带出露几个主要由碱长花岗岩组成的花岗岩基(包括庙儿沟、阿克巴斯套、克拉玛依及红山等岩体)。岩石学和元素地球化学研究表明,碱长花岗岩属于典型的铝质A型花岗岩,其10000×Ga A/l比值大。锆石的LAI-CPMS UP-b定年结果证实它们的形成时代均为～300Ma,与东准噶尔的碱性花岗岩体的侵位年龄一致。这些碱长花岗岩在成因类型上属A2型,形成于后碰撞的张性环境中。花岗岩的Nεd(t)=+6.42～+7.46,但众多地质地球化学特征显示它们不是直接来源于亏损地幔,而更可能是由洋壳和岛弧建造组成的年轻地壳部分熔融形成的花岗闪长质岩浆再经过分离结晶作用的产物。There are several batholiths mainly composed of alkali feldspar granites, including Miaoergou, Akebasitao, Karamay, and Hongshan plutons, outcropped along Darabut tectonic belt in West Junggar, Xinjiang. The results of studies on petrology and elemental geochemistry show that all these alkali feldspar granites are typically aluminous A-type granites, which are characterized by high 100 00 × Ga/A1 ratios. From the results of zircon U-Pb dating by LA-ICPMS, they were emplaced at about 300 Ma, being contemporary with alkaline granites in East Junggar. The alkali feldspar granites studied belong to A2 on petrogenetic type, and should be formed in a post-collisional tensional environment, εnd（t） values of these granites are high, ranging from ＋6.42 to ＋7.46, but many geological and geochemical characteristics demonstrate that these rocks were not directly derived from a depleted mantle, but most likely formed by fractional crystallization of granodioritic magmas which were produced by partial melting of a juvenile crust which mainly consists of oceanic crust and arc complex.

关 键 词：铝质A型花岗岩 锆石U-Pb年代 岩石成因论 西准噶尔 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]