阿尔金和东昆仑造山带中酸性侵入岩地质、地球化学特征及地质意义

GEOLOGICAL AND GEOCHEMICAL CHARACTERISTICS OF INTERMEDIATE-ACID INTRUSIVE ROCKS IN ALTYN AND EAST KUNLUN OROGENIC BELT AND THEIR SIGNIFICANCES

据青藏高原北部1∶25万区域地质调查资料,针对阿尔金和东昆仑造山带中主要出露的中酸性侵入岩类岩体地质、岩石地球化学特征进行对比研究,探讨原始古陆系统隶属关系.结果得出:岩体类型、岩石类型组合、成岩时代、岩浆系列、岩浆源岩物性及形成的地球动力学背景均可完全进行对比.认为前晋宁和晋宁期S型花岗岩类,可能是在碰撞造山地球动力学背景下,由成年期TTG陆壳局部或循环熔融形成;加里东和华力西期以I型和A型花岗岩类为主,推测是在一种大陆岩石圈伸展减薄或是大陆裂谷动力学背景下,由地幔基性超基性岩浆上侵引起中下地壳岩石局部熔融产生的一种岩浆作用产物,源区可能是副变质类型榴辉岩相和麻粒岩相下地壳.结合前人研究成果,初步提出阿尔金和东昆仑造山带古老基底同属一个古陆系统.

Based on the 1 ：250 000-scale regional geological mapping in the north of Qinghai-Tibet Plateau and contrasting the intermediate-acid intrusive rocks in the Altyn and eastern Kunlun orogenic belt, regarding of geology, petrology and geochemistry.The results show that the rock type,assemblage of rock types,rock era,magma series, source of magma and geodynamic setting can be contrasted completely.It is indicated that S-type granite in the former Jinning and Jinnin age was fromed by partial or cyclic melting of adulthood TTG continental crust in the collision geodynamic setting probably, and I and A-type granites in caledonian and variscan, presumably in a thinning of continental lithosphere or continental rift dynamic seting, may be derived from magma which was fromed by partial melting of lower crustal rocks intruded by mafic-ultramafic magma from mantle.The magma may be derived from the lower crust of vice-metamorphic eclogite phase and granulite phase.On the basis,combined with previous research, it is proposed that the basements of the Altyn and East Kunlun orogenic belt belong to the same ancient land system.