| The research area in Orogene, Inner Mongolia, located the junction of the southeast of Xing’an block and Songnen block, the east of Daxing’an mountains. Its east part near the Nenjiang fault, belonging to the north Daxing’an mountains metallogenic belt. It experienced the superimposition of the Paleo-Asian Ocean and Marginal Pacific tectonic domain, and multiphase tectonic evolution. There is an excellent geological setting for mineralization in the research area,the Chalukou Mo polymetallic deposit,Yili Mo deposit and other large and super large porphyry type deposits were found near the region these years, thus, it has a great potential for prospecting mines.The writer carried on the geological and geochemical characteristics and chronology work of the Verify area which selected latest data in this work based on the detailed field geological survey. By deeply study the geological feature of ore deposit, accurate determination of the formation age of the rock mass which is closely related to mineralization, the Genesis and metallogenic geodynamic background were confirmed. Based on the method which mentioned above and combined with geological, geophysical and geochemical characteristics, metallogenic prediction and ore-prospecting target delineate will be carried.1、The exposed strata in the verify area filed belonging the Longjiang formation, Guanghua formation, Ganhe formation which belong to lower Cretaceous and Wodouhe formation which belong to upper Silurian. The intrusive rocks are mainly of the granodiorite and monzogranite. The Mo ore bodies distributed in fractured granodiorite which near quartz vein and develop fine quartz vein and stockwork quartz vein. The main mineralized types includ molybdenite, chalcopyrite, pyrite, etc.The mineralized alteration zone can be divided into silicification, Potassic alteration, phyllic alteration, propylitization zone. According to the production environment and abnormal zoning, we preliminarily confirmed that the investigated molybdenum ore deposit area were porphyry deposit.2.The granodiorite and monzogranite of the research area belong to intermediate-acid granitoids, charactered I type granite and high-K calc-alkaline series. According to the rocks with High-Sr and low-Yb and without Eu anomaly, combined with occurrence environment, can be determined C type adakitic rocks. By using U-Pb zircon dating, obtain the ore-forming rock body age is 129-137 Ma, earlier than the mineralization. Therefore, the geochronology of diagenetic and ore formation is Early Cretaceous.It is the product of the middle Yanshanian(Cretaceous).3. There are four different metallogenic characteristics of molybdenum deposits and metallogenic stages in the daxing’an mountains region,the later periods are the greater mineralization scale or the peak of mineralization is middle Yanshanian Late Jurassic-Early Cretaceous in the east of the greater hinggan mountains,therefore,the metallogenic environment was in the Pacific subduction tectonic system,and formed in the extrusion to stretch transformation environment.The forming process is that the magma coming from the fused earth’s crust which rised emplaced and crystallized. The later crystallized magma taking hypabyssal place formed the ore-bearing fluid,it formed veinlet-disseminated mineralization when the pressure decreased, accordingly,it formed porphyry molybdenum body.)4.The results of Geochemical survey shows that Cu, Mo abnormal strength, matches well, in west and Pb,Zn,Ag abnormal conspicuous, matches better in east. Research areas delineated one A-type Mo-Cu polymetallic prospecting target. According to geochemical anomaly intensity, abnormal scale, the occurrence and grade of the ore body controlled by trench, comprehensive analysis the data of geology, geophysical and geochemical we can determined that there are potential to find medium-sized or above porphyry molybdenum polymetallic deposits in this region. |
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