STUDY ON THE MINERALOGY OF ECLOGITES IN THE DABIESHAN
Xie Douke, Ma chengan, Shi Hongqi, Liang Yongchai, Fong Jingjiang
The tectonic environmints of Dabieshan have long been discussed among geologists. In 1976, We raised the opinion that there perhaps may be a "fossil subduation" trending E. W. Recently we have system a tically studied the minerals from this metamorphic terrain of Dabie group in Hubei and Anhui, and their P-T Conditions. The lower proterozoic Wuhe group in Anhui is also considered.Phanerozoic formation discordantly overlies on these metamorphosed terrains. The radioactive age of zircon in Machao group are 1328, 1578 my., the age of biotite in Wuhe group are 1650, 1767, 1810 my. High P-Low T minerals, such as omphacite, garnet, crossite, barroisite, phengite, of barroisite-ecologite, amphobole-schist and granulite facies are the main subjects of this study. According to the study of minerals in Dabieshan metamorphic terrain we suggest that the Dabieshan was a plate boundary of paleoceanic plate in jinning cycle Low T-High P metamorphic belt was found in the southern side of the mountain, i. e., the oceanic side. Pressure decreased northward.