Geological Characteristics And Ore-forming Prospect Prediction Of Yaogou Au Deposit Inaohan Banner, Inner Mongolia

The study area is situated in northern Inner Mongolian Axis in north part of NorthChina Plate, and is geologically located in combining zone of North China plate andXingmeng Orogenic belt. And the metallogenic belt belongs to Chifeng-Chaoyang goldore belt of North China plate. Yaogou gold deposit is10km east of Nailingou golddeposit. In this area, the magmatism mainly appeared in the period of Late Permian,Late Triassic and Early Cretaceous, and Archaeozoic Wulashan Group gneiss and UpperCarboniferous Jiujuzi Formation sedimentary are found. The origin and prospect of thisdeposit is lack of understanding as it is a newly found. As a result, the chronologypetrography and geochemistry will be analyzed in this thesis besides the1:10000geochemical soil survey of mineralization anomaly area, and then the geologiccharacteristics, origin and prospect of Yaogou gold deposit will be discussed bycomparing with Binalingou gold deposit.The results of LA-ICP-MS zircon U-Pb dating show that there are not only lateTriassic adamellite but also Middle Permian biotite granite (262.9±1.2Ma). Thesebiotite granites are characterized by high-Si and Al and poor Fe, enrichment in LREEand LILE like Rb, Ba, K, etc., depletion in HREE and HFSE such as Nb, Ta, P and Ti.The samples are similar with post-collision granite with a few Al-rich minerals (e.g.,tourmaline). Yixian Formation is mainly composed of rhyolitic volcanic rocks. All thesamples from Yixian Formation have characteristics of high silicon and alkali contents,poor Ca and Mg, enrichment in LILE of Cs, Ba, K and depletion in HFSE of Nb, Ta, P,Ti and LILE of Ba and Sr, which is geochemically similar to A-type granite. EarlyCretaceous volcanic rocks are formed in extensional environment, which is influenced by the Pacific subduction.11metallogenic elements anomalous zones have been delineated according to the1:50000stream sediment survey, and17anomalies were further delineated in thesezones. Among them, Yaogou Au mineralization zone is priority anomalous zones withgreat mineralization anomaly and ore-forming prospect.NE and NW direction quartz veins, diorite porphyrite veins and granite-porphyrydykes are well-developed in synthetic abnormality area of Yaogou Au deposit, andskarnization can be seen in country rock, it is mainly controlled by NW-trend faults.The fluid inclusions in the Yaogou Au deposit point were dominated bye gas andfluid phases. And the homogenization temperatures were from159.1℃to245℃,within the range of medium and low-temperature hydrothermal fluids. The capturepressures of the inclusions in this deposit ranged from10.97MPa to25.93MPa，and themetallogenic depth was from1.10km to2.59km, indicating hypabyssal type. Bycontrasting Yaogou gold deposit and nearby Nailingou gold deposit, it is concluded thatYaogou gold deposit belongs to low-mesothermal remelting magmatic hydrothermaldeposit.Anomaly verification has been accomplished in the synthetic abnormality area ofYaogou Au deposit, mineralization of Au is obvious, it can be considered as aprospecting area to discoverer low-mesothermal remelting magmatic hydrothermaldeposits.