Study On The Geological Characteristics And Genesis Of The Main Deposits In The Wuxu Ore Field,Guangxi

Wuxu ore field is located in the southeast of the NNW trending Danchi metallogenic belt,and has developed a series of deposits with different element assemblage.Wuxu ore field is an important part of the Danchi metallogenic belt.In order to explore the genesis and relationship of each deposit,this paper studies the geological characteristics,metallogenic age,trace element characteristics of sphalerite,hydrogen and oxygen isotopes and sulfur isotope by taking the deposits of Bawang(Sn-Zn),Sanpaidong(Pb-Zn-Sb)and Jianzhupo(Pb-Zn-Sb)as research objects.And the conclusions and understandings of this paper are as follows:(1)The deposits of the Danchi metallogenic belt mainly occurr in the middle-upper Devonian,while the newly discovered Bawang deposit in the Wuxu ore field occurrs in the Carboniferous,which implies that there may also be some prospecting space in the strata outside the Middle-Upper Devonian in the Danchi metallogenic belt.(2)The distribution characteristics of deposits in Wuxu ore field are closely related to the structure.The deposits are mainly located in the tectonic fault zone,which shows obviously epigenetic filling mineralization.(3)The composition of sulfur isotope of Bawang,Sanpaidong(Pb-Zn-Sb)and Jianzhupo deposits in the Wuxu ore field shows that their sulfur sources were mainly magmatic sulfur mixed with a small amount of stratigraphic sulfur.The H-O isotopes of Bawang and Sanpaidong(Pb-Zn-Sb)deposits indicates that their source of ore-forming fluid is mainly a mixture of the magma water and the meteoric water(basin brine).(4)In-situ cassiterite LA-ICP-MS U-Pb dating of the Bawang deposit and the Jianzhupo deposit yields ages of 92±11Ma(n=18,MSWD=3.6)and 103±9.3Ma(n=15,MSWD=1.4)separately,which suggests that the metallogenesis was in the late Yanshanian.The Sanpaidong(Pb-Zn-Sb)deposit and the Jianzhupo deposit are relatively close in distance and both controlled by the NNW-trending fault zone.And association of mineralizing element of the Sanpaidong(Pb-Zn-Sb)deposit is similar to the Jianzhupo deposit.Therefore,this paper speculates that the metallogenic epoch of the Sanpaidong(Pb-Zn-Sb)deposit was also in the late Yanshanian.The metallogenic age of the main deposits in the Wuxu ore field is similar to the metallogenic age(98.6-89 Ma)of the main tin-polymetallic deposits and granite age(140-77.7 Ma)of the Dachang ore field in the Danchi metallogenic belt,which indicates that the mineralization of Danchi metallogenic belt occurred mainly in the late Yanshan,and the mineralization may be related to the late Yanshan magmatism.(5)The metallogenic temperature of the Bawang deposit and the Jianzhupo deposit is medium-high temperature.In the middle section of the two deposits,some medium-low temperature element combination deposits are developed.And the metallogenic age of the two deposits have some difference,about 10 Ma.Therefore,this paper speculates that there is more than one heat source mineralization center in Wuxu ore field,and based on this,the metallogenic model of the ore field is preliminarily established.