Phanerozoic metamorphism and crustal evolution in the southeastern part of China

Abstract

From the point of view of the metamorphic cycle, crustal evolution during the Phanerozoic in the southeastern part of China can be divided into two metamorphic cycles, i.e. the Palaeozoic metamorphic cycle (600-190 Ma) and the Mesozoic-Cenozoic metamorphic cycle (190-10 Ma), which separately reflect the different features of heat flow and geological environment. The Phanerozoic cycle from the Caledonian to the Variscan-Indonisian epoch, in which the Caledonian metamorphism is characterized by the low pressure type of regional dynamic thermal flow polymetamorphism, while the Variscan-Indonisian metamorphism is characterized by greenschist facies type of regional low temperature dynamic monometamorphism, reflecrs the changes of the heat flow cycle from higher to lower and the geological environment from active to stable. During the Mesozoic-Cenozoic, affected by the movement of Pacific Plate, the Yanshanian metamorphism led to the formation of the Changle-Nan'ao and Lianhuashan metamorphic belts characterized by the low pressure facies series, and the Danan'ao metamorphic belt characterized mostly by glaucophane greenschist facies. They must have occurred as paired metamorphic belts formed during the Yanshanian time. The Eastern Taiwan metamorphic belt characterized by burial metamorphism and the Western Taiwan metamorphic belt by low greenschist facies type of regional low-temperature dynamic metamorphism were formed during the Himalayan event in the Cenozoic.