| The tectonic site of the western Guangxi is located at the junction of the Yangtze paraplatform and the southwest margin of the South China fold system,and belongs to the Guixi depression of the Youjiang Regeneration Site in the South China paraplatform,the layered,layered and irregular veins intruded mafic flow and dikes are well cropped out around the Xilin-Tianlin area of Western Guangxi.The study for the petrogenesis of the mafic dikes will better understand the tectonic-magmatic significance of this region.The Emeishan Large Igneous Province(ELIP)is widely distributed on the western edge of the Yangtze Plate.As one of the most widely recognized igneous provinces in the world,its origin has attracted much attention.However,there are still many differences in the academic community regarding the origin of ELIP.The Pingxiang area in the west of Guixi is located in the region of the Youjiang Basin.The late Paleozoic stratum are extremely developed.The Oceanic island arc basalts and captures of metamorphic zircon found in this area may carry some deep information.Through the study of the main elements of the sample,trace elements,whole-rock Sr-Nd isotopes,and U-Pb-Hf isotopes of zircons of the Oceanic island arc basalts and captures of metamorphic zircons,this article gets some understanding:1.The basic rock type in the Xilin-Tianlin area of western Guangxi is alkaline basalt.The geochemical analysis has similar features with the high-titanium basalt of the ELIP.This paper believes that the basic rock formation in the Xilin-Tianlin area of western Guangxi is likely.There is close contact with ELIP.The basic rock in the Xilin-Tianlin area of western Guangxi is shown in the tectono-environment discriminant diagram,which shows that it is produced in the intraplate and is a series of alkaline basalts in the continental.2.This article synthesizes the published basaltic rock research results,systematically analyzes the main elements,trace element characteristics,and isotope composition of the ELIP basaltic rock,discusses the nature of the source area and the magmatic process,and recovers the original magmatic composition.The thermal structure of the source area and the temperature and pressure state of the melt closed are discussed,which provides a strong constraint for the structural background.Based on the above conclusions,combined with published geological data,this paper proposes a geodynamic evolution model that combines the mantle plume and ocean subduction.3.This paper uses the zircon U-Pb-Hf isotope system to constrain each other and analyzes the Oceanic island arc basalt found in the Pingxiang area of western Guangxi,and obtains high-quality age data of 907±8.9Ma,combined with the geochemistry before the research group.Analytical work has led to the Neoproterozoic Ocean Island arc basalts of the Pingxiang Oceanic island arc basalts in the west of Guangxi,indicating that there may be an oceanic subduction zone in the west of the Neoproterozoic period;analysis of the capture of metamorphic zircons in the basic rock,A metamorphic age of 438.4±7.8 Ma was obtained,which is consistent with the time limit of the Caledonian movement in South China.It shows that the tectonic evolution of the Pingxiang area in western Guangxi may involve the Caledonian movement. |
PDF Full Text Request