Geochemical Characteristics Of Diabase In Western Guangxi And Its Geological Significance

Western Guangxi is situated in the west of Guangxi.Its geotectonic location is located in Nanpanjiang area,which is the junction of South China,Indosinian and Simao massif.It belongs to the composite part of the Paleo-Tethys tectonic domain and the circum-Pacific tectonic domain.Large areas of the Late Paleozoic basic intrusive rocks are widely distributed in this area,mainly in Baise,Tiandong,Jingxi,Longlin,Funing and other places.Most of them are small layered or layered rock bodies,and diabase dikes are the main lithology.Previous studies on the origin of its rocks are divergent and there is no real conclusion.Therefore,the Baise diabase and its adjacent Funing diabase in Western Guangxi are selected as the research objects in this paper.Through the study of petrography,geochemistry and hydrocarbon composition,combined with the previous research data,the petrogenesis and tectonic background,characteristics of magma source area and regional metallogenic characteristics are mainly discussed from the perspective of geochemical characteristics.The main achievements are as follows:(1)Diabase in Western Guangxi is mainly quasi-aluminous alkaline basalt,which is characterized by high titanium,iron,magnesium and low potassium and sodium.The average ratio of Ti/Y is 549.5,more than 500,and the ratio of titanium dioxide is more than 2.8%,which belongs to typical high-Ti basalt series.(2)Large ion lithophile elements(LILE)K and Ba are both enriched and depleted,Sr is obviously depleted.And high field strength elements(HFSE)Zr,P,Hf and Y are obviously depleted,which indicates that diabase in Western Guangxi may be reformed by magmatic hydrothermal solution in later stage.Y is obviously depleted,which is mainly related to garnet residue in its source area.This indicates that the original magma of diabase in Western Guangxi may originate from low degree partial melting of the deep mantle,and has undergone a certain degree of contamination of the crust-derived materials and crystallization differentiation during the rising process.(3)Diabase in Western Guangxi is the product of the interaction between Emeishan magmatic cycle and Tethyan subduction,which was mainly formed in the intraplate tectonic environment of the continent.(4)It is difficult for Cu,Mn,Mo,Sn,Ag,Ti,Zn and Co related to diabase in the western Guangxi area to form mineralized(mineralized)bodies in a certain scale,which may form weak anomalies or form mineralized(mineralized)bodies in associated forms.(5)The deep and large faults in NW and NE directions provide hydrothermal channels for gold mineralization in the distribution area of diabase in West Guangxi,and diabase provides geochemical reservoirs for gold mineralization solution,indicating that diabase(especially altered diabase)in this area has a close spatio-temporal relationship with gold deposits as well as without genetic connection.