Dynamic Processes Of The Foreland Basin Of The South Yellow Sea And Basin-range Coupling Relationship

The South Yellow Sea Basin is a marine extension of the Lower Yangtze region,and its evolution through the marine basins, foreland basin, continental rift basins anddepression basin stage. Foreland basin stage plays an important role in the formationand evolution of the main structure of the South Yellow Sea Basin, and it also controlmigration and accumulation of oil and gas resources of the South Yellow Sea Basin.So it is of great significance to research the dynamic process of the foreland basinstage. The formation of this stage is related to subduction and exhumation of theYangtze plate to the North China plate during the Indo-China period, so the researchMesozoic orogenic process research can indicate the dynamic process of the forelandbasin of the South Yellow Sea inversion. Qianliyan uplift is located in the mostnorthern part of the South Yellow Sea Basin and it is the uplift zone in front of theNorthern Depression. Its formation is closely related to the Sulu orogenic processes,so the study of the dynamic process Qianliyan is of importance in revealing dynamicsof the foreland basin of the South Yellow Sea.This paper mainly research the geochemical and isotope geochronologycharacteristics of eclogite, gneiss and leptynite metamorphic rock of Qianliyan upliftof South Yellow Sea.It also study metamorphic origin and metamorphic dynamicprocess through contrast the Yangkou Haiyangsuo metamorphic geochemicalcharacteristics. Based on the existing geophysical data of South Yellow Sea, it alsoresearches the structural characteristics and structural styles of the South Yellow SeaBasin, and discusse the tectonic evolution of the South Yellow Sea Basin. On the basisstudy of the integrated basin-mountain, explore the intrinsic link between the twoforms.This paper concludes as follows:(1) The original composition of Qianliyan eclogite rocks may be ancient Qinlingoceanic crust, Haiyangsuo mafic metamorphic rocks may represent mafic lower crustof the northern margin of the Yangtze plate, and Yangkou eclogites’ are differentiationrock types of island arc basalts. Qianliyan eclogite protolith may be formed in the lateProterozoic, and its metamorphism time of coesite eclogite-facies is222±15Ma, thechronology instructs Qianliyan may belong to Sulu, and maybe extending in sea. (2)Most felsic rocks of the Qianliyan, Yangkou and Haiyangsuo have thecharacteristics of S-type granites, and a small part indicates the characteristics ofA-type granites. They may indicate lysis-collage process of Yangtze northern marginin Late Proterozoic together with other gneiss of the Sulu orogenic belt. Zircongeochronology indicates that the gneiss may have experienced a loss of Pb, and itformed in the late Proterozoic. It also experiences metamorphism in the Late Triassic.This feature is similar with Sulu gneiss characteristic. It also instructs the subordinaterelationship.（3）Qianliyan eclogites has similar thermal evolution contrast with Yangkoueclogite, suggesting that they experienced similar metamorphism. Haiyangsuo areasmay represent lower crustal rock units experienced superposition of eclogite-faciesbut not deep subduction high temperaturehigh-pressure metamorphism.(4)South Yellow Sea Basin developed a series of thrust, overthrust and imbricatestructure. This type of structure is closed related to Indosinian tectonic movement,latter tectonic movement superimposed on the structure of the previous and formtectonics mode nowadays.(5)There is coupling relationship between Sulu orogenic belt and the South YellowSea Basin foreland basin in formation time and the structural characteristics, theyformed during subduction of the Yangtze Plate to the North China plate in LateTriassic, which together make up the basin and range system.