Study On The Structural Nature And Minerlization Of Zhaoping Fault Belt In Northwestern Jiaodong Peninsula

The northwestern Jiaodong peninsula is one of the most important gold provinces in China. The annual gold output in this region is one fourth of aggregate yields of China. There are about 50 percent of gold deposits situated in the Zhaoping fault belt (ZPFB). Therefore, studying ZPFB is of theoretical and practical significance in analyzing the structural evolution, genesis of granite as well as the ore-forming process in Jiaodong gold province. Based on the studying on the feature of ZPFB, the Fushan gold deposit and the Jintingling gold deposit was discovered by the No.2 metallurgy exploration team in Shandong, Prof. Deng Jun from China University of Geosciences, respectively. The paper is a branch of the project in Zhaoyuan taken on by my Supervisor, aims to summarize the ore-forming principle and forecast new geologic prospecting targets by thoroughly studying on the nature of ZPFB. This paper is based on the detail field studying, takes the regional geology as setting, the theories of metallogenic series as a guide, tectonic mineralization as a system, and the deposit time-space evolution as principal line, and investigates primarily the ZPFB shape and the structure, alteration and mineralization zone. It also confirms the ZPFB activity nature and time sequence at different periods based on analyzing the states and changes of stress field in the northwest of Jiaodong at different stages and mineralization ages. The author has stipulated over again the ZPFB conformations and extensional directions. Based on detail field studying, the author decides that it is not true that the northern portion is connected with the southern portion after it extends to Zhaoyuan and terminates there, but the truth that it keeps on extending southwestward at Zhaoyuan. It is worth of knowing that Jintingling gold deposit is located in the extension of the northern sector of the ZPFB. For studying deeply on ZPFB, four sections are made from the turning site of the ZPFB at the north Zhaoyuan to Jintingling gold deposit by the author, and all the four sections show vast beresitize zone. Summarize the alteration and mineralization zones in main fault belts. The sequences of the alteration zones from the main fault section to the wall rocks on the lower wall are respectively: fault clay-beresitized rocks or beresitized granite-beresitized chip granite-potass granite. As a result, it often develops the disseminated ore bodies in the beresitized rocks, and often develops the pyrite veinule filled ore bodies in the beresitized chip granite and potass granite. The author considers that the ore bodies in ZPFB and sub-fault belts in lower wall show distinctively mineralization zones. the ore bodies in ZPFB belong to altered rock type and the dip angles are gentle, varying from 30o to 40o. But with the access to the footwall, the mineralization type transformed into altered rock type and quartz vein type. The ore-bodies become steep and their angles are from 40o to 70o. The mineralization type of those ore-bodies completely becomes into quartz vein type away from ZPFB and the ore-bodies become sub-vertical, even inverse. By summarizing the above principles, together with the analysis of typical gold deposit, stress field of ore-forming process and metallogenic time, the author brings forward three geologic prospecting target areas as follows: â‘ Jintingling type deposits should be prospected in the extensional direction of potouqing fault discovered recently â‘¡The alteration type deposits should be prospected primarily in the sector from qianliuxing to tengjia within ZPFB.â‘¢The quartz vein type gold deposit should be prospected within a series of quartz veins distributed in the footwall of the No.7 vein of Xiadian gold deposit.