Ganzi - Litang Gold Mineralization With The Metallogenic Model And Development Model

Ganzi-Litang Fracture Zone, in Western Sichuan Province, was situated tectonically in boundary area between the giant Songpan-Ganzi Orogenic Belt and Yidun Island Arc. From north to south, Gala gold deposit, Xionglongxi gold deposit and Ajialongwa gold deposit have been discovered and explored along the fracture zone in recent years, and also great gold potential has been prospected.This PhD thesis, mostly focused in tectonics, faults, regional geo-chemistry, mineralization and exploitation for gold deposits along the fracture zone, and it researched on regional geological setting, geo-physics, geo-chemistry in detail. On the one hand, the contents of the following elements Au,Mn,Cr,Ni,Co,V,Ti in different geological units such as stratigraphy or magmatite were lower than the crust Clark value, and the values of the elements Cu,Mo,Ag,Ba,W were near to the crust Clark value. On the other hand, the components of the elements Hg,Sb,As,Bi,Pb,Zn,B,Sn were conspicuously higher than crust Clark value. It was important for the gold deposit that the stratigraphy of Upper Triassic Qugashi Formation was characterized with higher value of Au than crust Clark value. But the value of Au in rocks of Tumugou Formation of Upper Triassic is lower than crust Clark value. However, the value of Au in sandstone, slate and phyllite of the strata is above 3.00×10^-9 and obviously higher than regional value. Finally, the thesis concludes that the area with a mixing geo-chemical anomaly of Au,As,Hg,Sb is the best place to metallogenetic predicting area for fine-desseminated gold deposit.Based on the careful investigation in the field, the thesis has devoted most of the time in studying on the following aspects, such as, geological conditions to mineralization, lithogenesis and metallogenesis, controlling factors for ore forming, and geo-chemical characters of ore deposits. The thesis has also researched on geological characters, mineral assembly of ore-rocks, alteration of host-rocks, characters of geo-chemistry, respectively, of the different gold deposit as Gala deposit, Xionglongxi and Ajialongwa deposit. The results of systematically analyzing on mineralogy, petrology, components of trace element and rare earth element, have proposed to this PhD thesis to the establishment of the geological characteristics and metallogenetic models of gold deposits along Ganzi-Litang fracture zone.Xionglongxi gold deposit was considered to be an epithermal fine-disseminated gold deposit (or sedimentary-rock-hosted gold deposit) controlled by fault. Regional deep-fault is the main pathway for rain water and deep earth paleo-geothermal fluids, subsidiary inter-layer fracture zone is the ore depositing structure for the ore-body. The fault tectonite, such as metamorphic feldspar quartzose sandstone and tuffaceous sandstone, was the main host rock, and slate was the main shielding layer in the deposit.