Characteristic and Genesis of the Au Deposits in Donghe Region, Southern Qinling

The Donghe gold deposit, served as a part of the eastern extension of southern Qinling Au-Pb-Zn deposit belt, is located in the west segment of southern Qinling. The mainly exposed strata in this area are Middle-Upper Silurian Zhouquyan Formation (S²⁺³) and Silurian-Devonian Dahedian Formation (S-D), meanwhile, the upper section of Zhouqu Formation (S²⁺³z³) serves as the main layer for gold mineralization in this region. The fault structures are fully developed, which are regional major ore-controlling structures, showing as an EW-trending interformational fracture zone with nearly parallel distribution. Within the regional tectonic fracture zones and its two sides, the quartz veins have close relationship with gold mineralization. Totally, 8 gold ore-bodies have been delineated there, all of them are distributed as nearly E-W trending. In which, the Au-8 is the major ore body with the length and thickness are 390 and 2.54 meters, respectively, meanwhile, its average gold grade is 2.41×10^-6. The Donghe gold deposits are mainly controlled by faults. Besides, lithology and magmatic rocks are also playing a certain role in the enrichment and formations of gold deposit. After analyzing regional geological background, geological characteristics of mineral deposit and ore-controlling factors, the Donghe gold deposit is classified as sedimentary reformed and superimposed exothermal-epithermal deposit.