Research On The Metallogenic Source And Genesis Of Wanquansi Ag-Au Deposit In Hebei Province

Wanquansi Ag-Au deposit is located between Shangluzhouwan and Xialuzhouwan in Wanquansi Chicheng Hebei province. And it is a middle Ag-Au deposit. The deposit is at the north of the Chicheng-Pingquan cutting-shell fracture, and the west of Shanghuangqi-Wulonggou fault.Basing on the predecessor's information and papers of Wanquansi deposit, we did some geological survey and testing analysis work. And the research on mineral, rock, deposit, deposit geochemical, and isotopic geochemics have been done. By doing these, we get to know the ore-forming geological characteristics, and we have done research on the metallogenic source and genesis of Wanquansi deposit.Field geological survey shows that vein of Wanquansi Ag-Au deposit is in the andesite and toscanite of Jurassic strata and diorite of Yanshan period. It is controlled by fractural crushed zone of the NNW-strike.We got the ore-forming age by testing the age of coarse-grained and fine-grained diorite, and by comparing it with the isotopic age of Ag-Au deposit in northwestern area in Hebei province, we got the information that the age of Wanquansi deposit is nearly the same to the deposits in northwestern Hebei province, and that they are all activated in Yanshan Period. It also shows that there used to be an important ore-forming activity of Ag, Au etc. polymetallic deposit during Yanshan Period in northwestern Hebei province.It is believed that the ore-forming materials drive from the deep earth, and the ore-forming fluids are dominated by magmatic water, mixed with minor meteoric water in the process of mineralization through the study of sulfur, lead, hydrogen and oxygen isotope.Through the study of geological characteristics, metallogenic role and genesis of the ore-forming materials, it is considered that the elements Ag, Au derive from the deep earth, and the revolving of the mantle is the drive of the up-moving of Ag, Au, while the large scale activity of granitic magma in Mesozoic and alkalization are the carrier of the up-moving of Au. Under the ultra high temperature and ultra high pressure in the deep earth, Au and its sulfides can only exist in gas, and move up with the poly-revolving of mantle. At last, the ore-forming materials deposit during the mantle branch evolution as the physical and chemical conditions change.