Abstract:
The Qinyingshan Formation in the Sufengshan area of Fujian Province consists of garnet, biotite and muscovite. The study shows that the protolith of the Qinyingshan Formation is mainly argillaceous rocks, which experienced rock slices subduction, deep buried squeezing and thrusting, forming subduction rock slices(I), deep buried squeezing rock slices(II)and thrusting rock slices(III)respectively. Among them, the subduction stage was middle-temperature and low-pressure metamorphism, the deep buried squeezing stage was high-temperature and middle-pressure prograde metamorphism, and the thrusting stage was high-temperature and low-pressure retrograde metamorphism. The main metamorphic minerals are garnet, biotite and muscovite, all of which have no girdle zone. Garnet and biotite from the samples of three rock slices mentioned above were used as a geothermometer. Combined with muscovite geobarometer, it can be estimated that, during the tectonic evolution processes of metamorphic rocks, the temperatures and pressures of the subduction stage, the deep buried squeezing stage and the thrusting stage were estimated 594~622 ℃ and 0.28~0.52 GPa, 629~655 ℃ and 0.6~0.7 GPa, and 476~495 ℃ and 0.09~0.1 GPa respectively.