壳内熔融与大陆造山--中山大学地质学系成立90周年暨陈国达院士诞辰102周年纪念

摘要

Orogeny is classified into two types in this paper: folding orogeny of geosynclines and reactivating orogeny of cratons, both of which are related to plate-convergence. The conversion of oceanic crust to continent during geosynclinal orogeny is marked by the appearance of TTG rocks. The TTG series is commonly referred to as ‘immature granite’ generated from first-time melting of geosynclinal sediments. The increase of the temperature of continental crust, due to energy transformation during subduction, results in melting or remelting of sialic rocks in the upper-middle crust of continent that includes the TTG rocks formed in geosynclinal orogeny. The melting processes lead to the formation of the ‘mature’ undertint- or leuco-granites. The formation and accumulation of the intra-crustal magma layer will ultimately cause a large-scaled crustal deformation of continent, i.e. cratonic reactivating orogeny. Both poly-phase of orogeny and poly-episode of granite activity are explained as the products of multiple crustal melting that also generates granite-layers with progressively younger ages.%本文将造山作用分为地槽褶皱造山和地台(克拉通)活化造山两种类型，并认为两者均起因于板块的汇聚过程。地槽造山是洋壳向陆壳的转换过程，其标志是地槽沉积物初次熔融形成的、以 TTG 为主的“不成熟花岗岩”产生。板块俯冲过程的能量转换，导致大陆岩石圈内能升高，包括 TTG 在内的基底地槽构造层的再次熔融(重熔)，产生再生或重熔岩浆形成活化造山期的“成熟花岗岩”；壳内重熔岩浆层形成和增厚最终导致大陆克拉通发生大规模压缩变形(活化造山)。造山作用的多幕性和花岗岩活动多期性，以及上老下新的花岗岩“层序”，被认为主要与板块俯冲过程的能量转换速度有关。