东秦岭河南伊川-湖北宜昌地学断面地壳岩石组成、化学成分及形成机制

Petrological Model,Chemical Composition and Possible Genesis of the Crust Along Yichuan-Yichang Global Geoscience Transect(GGT) in East Qinling

系统测定了河南伊川－湖北宜昌地学断面及其邻区主要岩性９９件样品高温高压条件下地震纵波速Ｖｐ值，将结果与地表地质、地震测深获得的地壳速度结构资料相结合，建立了研究区内四个构造单元地壳岩石组成模型，估算出地壳各层的平均成分。秦岭地壳总体成分是闪长－花岗闪长质的，地壳分异程度较低，地完成分和地球物理研究结果表明，秦岭造山带在其发展过程中可能存在过板底垫托物质，但拆离作用已使现今造山带不存在山根，垫托物质很少或已返回上地幔。

On the basis of geochemical study, laboratory study of seismic velocity (Vp) of 99 rock samples at high temperatures and high pressures, geological study, and the QB-1 Multiple Sounding Section of the Qinling Orogenic Belt and its adjacent North China Craton and Yangtze Craton, the models of petrological structure and composition in the four structural units have been established. The results imply that the regional crust, which proposed to be granodioritic to quartz--dioritic in composition, is poorly differentiated. It is possible that mafic underplating at the base of the crust might have occourred, but the dilamination has indeed played an important role in the past time in the Qinling Orogenic Belt.