The discovery of the intermediate and basic volcanic rocks in the Dachang ore deposit,Guangxi,and its geological significance

The discovery of the intermediate and basic volcanic rocks in recent years in the Devonian strata in Dachang Guangxi has important significance in the explanation of the tin ore formation mechanism and the prospecting research.The authors analyzed its volcanic output characteristics,petrology and rock geochemistry and explored the relationship between the volcanic rock and the mineralization.The results show that the volcanic rocks are mainly basalt and andesite.The volcanic rocks are in conformable contact with the surrounding upper and lower rocks,with a lot of classic sedimentary structure characteristics of laminations and stripes,and the output position of the volcanic rocks contains a lot of marine fossils of tentaculitoid.The above evidence indicates that the eruption environment of the volcanic rocks is sea facies.The analysis shows that the ore is closely related to the layered volcanic rocks and shows consistency and continuity with the layered volcanic rocks,and ore sources may be related to the volcanism.It is concluded that the ore deposits in the study area should be of the type of marine volcanic-sedimentary exhalative hot water plus later superposition and alteration.