Study Of Gold Mineralization Features Of Alkaline Complex Rock Mass In Longbaoshan Area Of Cangshan Country

Magmatic activities of Longbaoshan area in Mesozoic Early Yanshan stage are formed in the volcanic back-arc tensional environment, closely related to magmatic activity of shoshonitic rocks in eastern China, which might initially come from the same magma chamber of the upper mantle, mantle-derived magmas assimilated a number of crusts and crystallized into crust-mantle mixed-source products and obtained some useful components. Intense tectonic movements provide channel and mineralization space for the activation, migration, enrichment and sedimentation of gold elements. Archean metamorphic rocks are the initial ore source of gold mineralization in this area. Considering thermal power structures phenomena that there are a large number of Cambrian xenoliths and aureole breccia in the rock mass, the thesis infers that Longbaoshan rock mass provides important mineral sources and heart source for the gold mineralization in this area. Gold deposits in Longbaoshan mineralized in the late Early Cretaceous to early Late Cretaceous and the mineralization age of Longbaoshan (including quartz veins feldspar K-Ar) is 96.2Ma. Ore-forming fluid is of low temperature and low salinity.In this area, sedimentary rocks show micro-magnetic and non-magnetic and high-precision magnetic survey reflects a stable magnetic field; intrusive rocks show unevenly in magnetism and high-precision magnetic test results reflect mutation in magnetic field. Around the ore deposits, the contents of gold and its related elements significantly increase. According to the soil elements geochemical map, the anomalies of element Au distribute in small local anomalies, scattered, low amplitude and of no obvious concentration centers.For the purpose of researches, the thesis also arranged seven lithogeochemistry profiles in Cangshan area, respectively in Erdaowan, Ximashan, Dongmashan, Wujiagou, Yihezhuang, Shaiqianzhuang, Xidabu. Among them, the contents of Au, Ag, Pb in Wujiagou profile are 40.89,31.30,11.85 times of the contents in upper crust, with good prospect; limestone and silty shale in Yihezhuang profile, especially Ag, Cu, Pb, Zn, As, Sb and Bi in limestone, have very good prospect; the content of Au in diorite porphyrite in Xidabu profile is also very high; gold and multi metallic elements only show weak anomaly in Erdaowan, Dongmashan and Shaiqianbu profiles; contents of all the eight elements in Ximashan profile are very low and of no worth for further study.According to the difference in storage place and mineralization features, Longbaoshan area could be divided into limonitization quartz vein, altered breccia, intrusive breccia and limonite silicified sandstone. Gold ore mineralization in Lianziwang-Shaiqianbu could be divided into skarn, crushed zone altered rock and quartz vein.