咸沟岩体地质地球化学特征及成岩机制探讨

咸沟岩体位于华北地台北缘西段．主岩体为二云母花岗岩，成岩时代为３９９．８±１．８２．１Ｍａ，内有岩浆演化晚期的白云母花岗岩侵入，与主岩体有迥然不同的地球化学特点．前者显示出不同地壳物质混合的岩浆特征，后者属典型的Ｓ型花岗岩．结合区域构造演化分析，认为咸沟岩体形成于拉张环境，源岩可能为下地壳的英云闪长岩．下地壳的深熔岩浆在上升迁移过程中，遭受了富含泥质的陆壳物质的强烈混染，混染岩浆向Ｓ型岩浆方向演化．

An Inquiry into the Geological and Geochemical Characteristics and Petrogenesis of Xiangou Batholith

The Xiangou batholith is situated in the western part of northern margin of North China platform. The main body is dimicaceous granite, which had been formed in 399.8 1 8 -2 1 Ma, and intruded by later muscovite granite of magmatic evolution. The Geochemical characteristics of muscovite granite are notably different from those of the main body. The former shows the mixed magmatic features of different crustal matters while the latter belongs to the granite of typical S type. Combined with regional tectonic evolution analysis, the Xiangou batholith is supposed to have been formed in the extensional environment and their sources can be tonalites of lower crust. The anatexis magma of lower crust, when moving up, had undergone intense contamination of continental crustal matter that was rich in pelites. The contaminated magma had followed the evolution of S type magma.