摘要:
本文着重通过华北陆台北部冀东、密云、阜平、五台山、恒山、卓资—阳高、集宁、千里山等几个主要变质地区的热动力条件的研究,讨论其时空分布特点和演化规律,进一步研究变质作用特征和地壳演化的热历史。
Abstract:
Archaean-Proterozoic metamorphic rock seriesis extensively distributed in the North China Platform.The difference of thermodynamical conditions of metamorphism shows evolution characteristics of the North china platform. Study of thermodynamical conditions of a few typical metamorphic regions indicates that these areas,such as eastern Hebei,Fuping,Miyun,Hengshan, Zuozi-Yanggao,Jining and Qianlishan,belong to Archaean metamorphic regions of granulite facies. The difference of thermodynamical conditions and rocks associations demon- strates that they are products at different erosion depths.Metamorphic temper atures in these areas are over 750℃,and pertain to regional high-temperature metamorphism.Various pressures show that these rocks were formed at different of the crust.During the late Archaean-early Proterozoic,there were amphibolite facies and greenschist facies of regional dynamical thermal flow metamorphism,and in the late Proterozoic,regional dynamical metamorphism of sub-greenschist facies developed in the North China platform.With time, from Archaean to Proterozoic,the thermal flow of the crust had a tendenog to decrease,and the strength of metamorphism weakened obviously. The changes from regional high-temperature metamorahism through regional dynamical thermal flow metamorphism to regional dynamical met- amorphism again represent the processor variation of thermal dynamical conditions during the history of the crust.They demonstrate all the evolution history of the crust from activity to stability
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