Fluid Inclusion Characters Comparison Of Gold Deposits Of Qinling Mountain

Qinling region is one of the major gold producing area of China. According to thegeological structure and distribution of gold deposits, Gold deposits occurred in threedistrics: XiaoQinling-Xiong’ershan, northern belt of South Qinling and southern beltof South Qinling.Gold deposits in southern belt of South Qinling are hosted in Triassicnon-metamorphic clastics and carbonate rocks mainly. In northern belt of SouthQinling, the host rocks of ore are Devonian metamorphic fine clastic rocks. Golddeposits in Xiaoqinling-Xiong’ershan district are hosted in Archean and Proterozoicmetamorphic rocks.The lowest temperature, salinity and pressure of mineralizing fluid is thecharacteristics of gold deposits in southern belt of South Qinling which discriminatefrom others. Although the temperature and salinity of mineralizing fluid inXiaoqinlin-Xiong’ershan are slightly lower than that of northern belt of South Qinlinggold deposits, the pressure is the highest in three districts. Oxygen and hydrogenisotope data of ore fluid in southern and northern belt of South Qinling show similarcharacteristics which indicates the fluid source of both districts are similar. Influentedby sedimentary host rock, Oxygen isotope value of both districts are higher thanXiaoqinling-Xiong’ershan in which the host rock of gold deposits are metamophicrocks. The mixture of mineralizing fluid and meteoric water of Xiaoqinling-Xiong’ershan cause the lowest δ18O value in three districts and also make the δD moredispersed than others. Metamophic water is the source of the mineralizing fluid in allthree zone.Chronology studies show that gold deposits in South Qinling belt (includingnorthern and southern belts) are formed in the late Triassic-early Jurassic. Golddeposits in Xiaoqinling-Xiongershan are formed in two periods, the early Triassic and early Cretaceous.Gold deposits in southern belt of South Qinling are Carlin andCarlin-like type mainly. Orogenic gold deposits are major type in northern belt ofSouth Qinling and Xiaoqinling-Xiong’ershan. The gold deposits in southern andnorthern belt of south Qinling belong to same metallogenic series in same tectonicbackgroud but forming at different depth of the crust. Erosion intensity becomesweaker and weaker from east to west as well as north to south; which dominate thedistribution of gold deposits in Qinling. Considering source of mineralizing fluid, oreforming depth, and erosion, we suggest that there are considerable amount of orogenicgold deposits developed beneath the Southern belt of south Qinling.