Geological And Geochemical Characteristics And Prospecting Direction Of The Dongfengbeishan Molybdenum Deposit In The Tianbaoshan Mining District,Eastern Jilin Province

Dongfeng Beishan molybdenum deposit is located in the eastern Jilin Tianbaoshan mining area, where, belong to the west part of Yanbian eugeosyncline fold belt, the east par of the north margin of the North China Craton, are discovered multi-origin, multi-type,multi- source, multi-period and multi-mineral deposits. The Tianbaoshan mining district is also loacated in the conjunction of the Western Circum Pacific metallogenic domain and the paleo-Asian metallogenic domain. This study area is favorable for mineral exploration by the superior natural geography and the convenient transportation.The study area produces Variscan- Yanshanian intrusive rocks, and Yanshanian porphyry monzonite granites are the main metallogenic intrusions. The strata in the study area for the Proterozoic Mesozoic Cenozoic, distribution in different regions, mainly composed of a series of quartz schist belt. The NW trending faults and the contact zone of Yanshanian monzonite porphyry and the Paleozoic volcanic rocks, which developed in the study area, are the main ore-controlling structures.The ore bodies, of which most are hosted in monzonite porphyry body with NW schist belt, and a few are hosted in quartz diorite porphyry and granodiorite body with NW schist belt, and the others are hosted in the contact zone of intrusions and volcanic rocks,are hydrothermal vein type. In addition, these ore bodies are generally small, and mostof them are concealed with vein shapes.The metallic minerals, from Dongfeng Beishan molybdenum deposit, mainly are molybdenite, and followed by associated chalcopyrite, sphalerite, galena, pyrite, pyrrhotite,magnetite, limonite, malachite and molybdite. Whereas, the non-metallic minerals are quartz, diopside, chlorite, epidote, zeolites, calcite and granite-like rock-forming minerals.The deposit wall rock alterations are relatively simple. Of which the most are silicification and potassic alteration, and the secondary altered by chlorite, epidote, silicide,and the other altered minerals are sericite, carbonate and zeolite from lately episode, and supergene kaolin.The temperatures of ore-forming fluids from Dongfeng Beishan molybdenum deposits are high in the quartz- molybdenite stage and low in the quartz- polymetallic sulfide stage, according to our fluid inclusions tests and previous studies. The ore-forming fluids are in low pressure with moderate salinity, and the mineralization depths are shallow.Using molybdenite Re-Os isotopic dating method, the Dongfeng Beishan molybdenum deposit obtains isochron age of 191.9 ± 3.3Ma, showing that mineralization era are the early Yanshanian Jurassic.The Dongfeng Beishan molybdenum deposit is hydrothermal vein type, determined by Geological and geochemical characteristics and the geological setting. And there may be a large-scale porphyry molybdenum ore body in deep showing by ore-forming fluids characterizes.