Geologic Feature Of DaDi Silver-polytmetallic Deposit And Its Metallogenic Model In The Inner Mongolia

Southern part of Da Hinggan Mountains is an important silver polymetallic metallogenic belt. The DaDi silver polymetallic deposit is located in the southwest part of Da Hinggan Mountains within Heshigten Banner, it is a medium-sized silver polymetallic deposit found in recent years. Through the metallogenic background, geological features, ore-controlling conditions, stable isotope and fluid inclusion studies, the results showed that:1. Mesozoic yanshanian tectono-magmatic action was the important condition of mineralization in the area.2. Ore-forming materials came from deep crust or mantle. Mineralization mainly in low temperature.3. This deposit was hydrothermal filling type deposit controlled by tectonic intrusive rocks and related to yanshanian intrusive rocks.4. The deposit was strictly controlled by fracture and fracture structure:its NE trend fault zone was the passage of ore fluid and NW-trending faults, fractures were the important structure for ore-controlling.5. The genetic model of the deposit was established:From late Jurassic to early Cretaceous, influenced by the subduction of paleo-Pacific Plate to Eurasian Plate, the basaltic magma added to the lower crust underplating way,, and leads to the partial melting of crust and crustal uplift. Due to the rich polymetallic mantle and heated lower crust molten material were mixed in different proportions to form the syntectic type magma. The magma rose along the north-east deep rupture, forming granite intrusion. And in the late stage of magmatic emplacement, a large number of carrying materials such as volatile and Pb, Zn, Ag metallogenic fluid surrounded by the heated precipitation migrated to the near surface along the north-east deep rupture. Due to changes in physical and chemical conditions such as the decrease of temperature and pressure, the hydrothermal metallogenic material was prompted for precipitation, concentration and mineralization in the favorable places.6. Geophysical and geochemical anomalies, construction, alteration is the best prospecting mark. Comprehensive analysis, by exploring deep deposit, there should be a larger deep prospecting space in mining area. Also in the area, along the north east to ore belt which is in DaDi～DaJing and the west of DaDi, it was still possible to find ore deposit of a certain scale.