Abstract:
Jiangxi extends across two first-order tectonic units, the Yangtze paraplatform region in the north and the South China fold system in the south. Two metamorphic rock series exist there, which respectively formed in the Jinningian and Caledonian folding orogenic movements. In the folding orogenic phase of the early geosynclinal reversion, occurred dynamic-pressure metamorphism of the greenstone-facies sericite-albite type, which is also referred to as "Ⅰ"-type metamorphism. It is of areal distribution, belonging to this type of metamorphism. In the block-faulting orogenic phase of the geosynclinal reversion, occurred dynamothermal metamorphism of the amphibolite facies. It is of zonal or domal distribution, belonging to the polymetamorphism, but the facies changes greatly; stress and heat are the compound factor responsible to this type of metamorphism. It is mostly distributed in uplift zones of a geosyncline, in areas with distinct thermal anomalies along fractures. The heat was derived from deep-seated magmas or regenerated magmas. It is also called "Ⅱ"-type metamorphism. The "Ⅰ" type occurred before the "Ⅱ" type. In the "Ⅱ"-type metamorphism one may recognize two kinds of metamorphism: one is low-pressure metamorphism of the andalusite-silimanite type and the other is moderate-pressure metamorphism of the kyanite (-staurolite)-silimanite type. The former is more typical. In the stage of platform development, regional metamorphism in the main ceased; while in the stage of the activity of continental margins, crustal movements reactivated and contact metamorphism dominated by thermal activity of magmas was widely developed. Thus the continental crust or granites in Jiangxi province formed finally.