Research Genetic Mineralogy Of Jinkeng Gold Deposit In Shaowu,Fujian Province

Western Fujian is the main prospecting area for gold deposits in Fujian province.The previous research focuses on the metallogenic area represented by Zijinshan in southwest Fujian,but less research has been done in Northwest Fujian.In recent years,more than 60 gold deposits(points)have been found in the northwest Fujian,which has aroused the interest and enthusiasm of the researchers.Shaowu Jinkeng gold deposit is located in the uplift belt in the north of Fujian,orebodies occur in the Cambrian Lintian Group,but no any scholar has carried out detailed studies on the mineralogical characteristics and genesis of the gold deposits.In this paper,on the basis of field geological surveys,the typical rock and ore samples were collected by drilling,using electron microscopy,electron microprobe analysis,X ray diffraction analysis,fluid inclusion microthermometry and other methods to study Petrography,mineralogy and inclusions,and then the characteristics of the main minerals and the genesis of the main minerals are discussed,and from the mineral point of view study the genesis of the deposit,obtaining the main achievements as follows:1.The ore minerals of the deposits areelectrum,chalcopyrite,galena and sphalerite;the main gangue minerals are quartz,pyrite,calcite,dolomite and sericite,containing a small amount of rutile,plagioclase,potassium feldspar and chlorite,and the generation sequence of the main minerals is divided.It is believed that the genesis of minerals is related to deposition,metamorphism and magmatic hydrothermalism.2.The pyrite and chalcopyrite universally contain Au and the content is high;galena and sphalerite do not contain Au and Ag.The ratio of w(Fe)/w(S+As)in pyrite indicates that the formation depth is shallow;The Co/Ni ratio of pyrite is mostly between 1-5,indicating that it is mainly caused by magmatic hydrothermal solution,Co-As-Ni diagram also shows that it is mainly related to magmatic hydrothermal fluids.3.The fineness of gold in the deposit is not high,with an average of 719.The occurrence of gold is mainly in the form of electrum with quartz in the pyrite crystal gaps,fissures,or independently in pyrite pits.The occurrence patterns of gold are significantly different the representative deposits in southwestern Fujian and central Fujian.4.The crystal cell parameters of pyrite,quartz,chalcopyrite,galena and sphalerite are all different from those on the PDF card,but the diffraction peaks of minerals are basically the same as the standard peaks,indicating that the transformation of hydrothermal fluids in Jinkeng gold deposit has little effect on the crystal form of the minerals.5.The studies of fluid inclusions show that ore-forming environment salinity ranges from 0.35%?10.77%NaCl eqv,with an average of 5.25%NaCl eqv,and this belongs to the low salinity;the main metallogenic temperature is 160-280?,belonging to the middle-low temperature mineralization;metallogenic pressure is 124.2-330.2 X 105 Pa and mineralization depth is 0.414?1.10kn,the mineralization depth is shallow.6.According to the comprehensive study,the type of the deposit is the epithermal middle-low temperature sedimentary metamorphic-hydrothermal superimposition gold deposit,and the magmatic hydrothermalism in the later period is the main metallogenic period.