Mineralization And Ore Prediction In Guojiatun Pb-Zn Deposit, Northern Hebei Provice

Guojiatun Pb-Zn deposit was located at the side of NE-trend Qipanshan fault. Yanshanian volcanic basins and volcanic mechanisms were distributed in the ore district and periphery. The main ore-hosting structures are F1fault with the strike of NS and F2, F3faults with the strike of NW. The main ore-hosting rocks are Jurassic pyroclastic rock of Zhangjiakou group and Hercynian granite. The main types of wall rock alterations included potash feldspathization, beresitization, propylitization and so on.Joint statistics show the main stress of F1fault in metallogenic stage is the dip327°∠7°, and the fault is a shearing left-lateral fault. The main stress of F2, F3fault is the dip196°∠77°, which shows that the tow faults are tensional faults.Principal component analysis of the rocks showed that the composition of tuff are close to trachyte and dacite, granite belonged to alkali feldspar granite. There had obviously material exchange between the tuff and the granite, Si was transferred to the tuff from the granite, K, Ca, Mg were transferred the granite from the tuff in the process of alteration. The increased contents of CaO、MgO、CO2in the altered rock was caused by carbonate alterations. There had a trend that the rare earth elements in the tuff were transported to the ore and granite in the process of mineralized alteration. Trace elements analysis show that Pb, Zn, Ag, Cu occurred significantly enriched in beresitization of the tuff and granite as well as the broken fault zone.The metallogenic period of Guojiatun Pb-Zn deposit belongs to Yanshanian age. The mineralization is linked to the activities of continental volcanic rocks. And the metallogenic material come from the tuff and granite. The dynamic hydrothermal convection mechanism and the electrochemistry induction mechanism were the key of the formation of ore deposits.According2.56km2tectonic geochemistry survey, combined with multivariate statistical analysis, Pb-Zn-Ag-Cu were determined as the best Pb-Zn prospecting elements combination mark. According to element association anomalies of tectonic chemistry and the information of geological alteration,7prospecting targets were delimitationed and were divided into A, B, C levels.