The Analysis Of The Surface Tectonic Characteristics And The Geodynamics Process Of The Sulu Orogenic Belt

The China’s Central Orogenic Belt consists of western Kunlun-Qilian-Qinling segmentand eastern Dabie-Sulu segment, and Sulu orogenic belt is in the most eastern section. As aMesozoic orogenic belt, the Sulu orogenic belt is also an ultra-high pressuremetamorphic(UHPM) belt, which represents a deep subduction and exhumation. Therefore,the Sulu region has aroused widespread interest and research.Based on previous studies, geological investigation and map reading, this paper analyzesthe composition and geometric formation of Sulu orogenic belt. Then it summarizes thesurface tectonic characteristics of the orogen. At the same time, the paper interpretates thegravity data, areomagentic data, magnetotelluric depth sounding data, seismic tomographicdata and seismic reflection data to understand the characteristic information of the depth.Based on the above analysis, it derives the geodynamical process and sums up the stages oforogenic evolution corroborated by paleomagnetic data at last.The geological background of the Sulu region before the orogenic process can besummarize as follows.First, before the Cambrian period, this region had experiencedinterchangeably stages of deposition and magmatism. Second, there was no deposition orintrusion event in a wide range during the Paleozoic. Third, Late Permian to Early Triassic,the eastern oceanic crust of the North Paleo-Tethys began to subduct down to the North Chinaplate, which opened the prelude of the orogenic time. This time continued throughout theMesozoic, ended at Paleogene. We can divide it into five stages: Early subduction (ie, Sulusubduction) stage during the Middle Triassic, extension and exhumation stage during the LateTriassic, late subduction (ie, Yangtze subduction) stage last form the Early Jurassic to themiddle Jurassic, combination stage during the Late Jurassic and extension and thinning stagefrom the Late Jurassic to the Paleogene period. When orogenesis came to the end, the activities of the circum-Pacific tectonic domain strengthened and became the dominant factorsof tectonic activities in this area, which shaped a complex geological picture of today’s Suluorogenic belt.