METAMORPHIC FEATURES OF THE MESOZOIC METAMORPHIC ZONE ALONG THE COAST OF FUJIAN

The metamorphic zone under discussion is situated on the west coast of the Pacific Ocean, along the southeast coast of China. It is elongated in a northeast direction, parallel to the coastline. This zone is composed of the Upper Triassic—Upper Jurassic strata. There are a variety of metamorphic rock types. With the main exposed location of the Changle-Nan’ao deep fracture belt as the boundary, low-grade metamorphic rocks such as schistose volcanic rocks, phyllite and metamorphic sandstone occur in the west, while medium-grade metamorphic rocks such as schists and granulite occur in the east. In this paper, it is suggested through a brief introduction of original rock formations that the metamorphic zone formed in the active zone of the continental margins. Its sedimentary environments grade from west to east from continental sedimentation and volcanic eruption to epicontinental depression volcanic sedimentation. The authors discriminate three progressive metamorphic facies, the lower greenschist facies, the higher greenschist facies and the lower amphibolite facies. They are distributed successively from west to east, with a narrow range of lateral changes. Besides, according to the wide occurrence of andalusite and sillimanite in the low amphibolite facies and the development of granitic rocks in different evolutional stages, the authors have determined this zone to be a typical low-pressure regional metamorphic zone, whose formation is quite closely related to tectonic activity. As the Pacific plate is subducted towards the Eurasian plate, the continental margins have become a strong active tectonic zone and a geothermal anomaly zone, thus giving rise to a striking Mesozoic metamorphic zone along the coast of Fujian.