| JinLing gold deposit is located in JinLing town, Zhaoyuan city of Shandong province,belonging to Zhaoyuan-Laizhou mineralization belt of Jiaodong gold concentrated area.There are four mines in scale which are Bushang mine, Bunan mine, Jinlangou mine andNanjie mine. They are all controlled by Ling-bei fault and its secondary faults.The main strata exposed are Jiaodong group and Quaternary. Jiaodong group mainlyexist as remanents, and the number of remanents reduce from South to North. Mesozoicmagmatic rocks are widely distributed as the main surrounding rock. Linglong biotitegranite is located in the south, and has the same gneiss as Jiaodong group, and isin-situ replacement, semi-in-situ remelting genisis. Guojialing granite exposed in the northof mine is also called Beijie pluton, it invaded into Linglong granite, and is crust-mantlemixing causes. Faults developed in the mines, and Lingshangou-Beijie fault and itssecondary faults controlled the occurrence of gold veins. There are two groups of normalfaults destroying the veins, which are south-north faults and northwest faults.These are the geological features of the four mines: All the veins of four mines arecontrolled by the NE strike, dip SE faults with dip angles＞70°except the1#vein ofBunan mine which is NNE strike; ore bodies in Bushang and Nanjie mines are bigger, andextend continuously in deep, while ore bodies in Bunan and Jinlangou mines are small anddistribute seperately; Ore types include mainly beresite and beresitizational graniticcataclasite, and quartz vein ore is widely found in the shallow of1#vein of Bunan mine; InJinlangou mine, natural gold, electrum and pyrite are the only ore minerals, while chalcopyrite, galena and some other polymetallic sulfide are also distributed in theother three mines; Ore structures include disseminate, mesh-vein and massive structures.Wall rock alteration types are mainly potassium, silicide, beresitization andcarbonatization. Types, degrees and zonation of alteration are different in different mines.There are two two epochs of mineralization process in Bunan mine, which are goldmineralization in Early Cretaceous and polymetallic-gold-silver mineralization in lateCretaceous. The second mineralization has a close connection with orthoclase porphyrywhich provided the ore-forming fluids rich in Ag and multi-metal.Ore-forming fluids are characteristic of low salinity, low density and consist ofCO2-H2O-NaCl±CH4. Fluids immiscibility obviously occurred during mineralization.The temperature at the main stage of mineralization is280~320℃, the ore-formingpressure is60~94Mpa with depth of6.22~7.98km. As for the mineral source, sulfer isderived from Mesozoic magma, Au is derived from Jiaodong group, Mesozoic magma andmantle, ore-forming fluids are derived from mantle fluid and magmagicwater superimposed by meteoric water in late-stage. In conclusion, Jinling gold mines areintermediate orogenic gold deposits.Ziron U-Pb dating shows the forming ages of Linglong granite, Guojialing graniteand the orthoclase porphyry are159Ma,127.9Ma and94Ma. Based on the geochemicaland regional features, it suggests the three ages represent the tectonic settings ofcompressional, transforming from compression to extension, and extension environment,which is caused by the subduction of Pacific plate.Based on the study of fault fractures, orebody space location rules and othermineralization enrichment features, we forecast six prospecting target areas of level oneand twenty-three target areas of level two considering the influence of faults destroyingand exploration geochemistry messages. |
PDF Full Text Request