Metallogenic Regularities And Prospecting Direction Of Halasu-Hadansun Porphyry Copper Belt In The Northeast Margin Of Junggar

The porphyry copper belt of Halasu-Hadansun,northeast margin of Junggar is perhaps part of western extension part of the Mongolia metallogenic belt which belongsto central Asia-Mongolia mineralization domain,including many important porphyry copper deposits,such as ouyutolgoi and chagan subul deposits. Therefore,there wasenormous metallogenic potential in that area. In recent years, Xileketehalasu andYulekenhasula porphyry copper deposits and many other porphyry copper mineraloccurrences were discovered consecutively in this belt. Based on the field works such asgeological survey and ore occurrences check in metallogenic belt, together with study ofpetrography, mineralography, fluid inclusion and isotope geochemistry, this papergeneralizes a few conclusions as follows:The newly-discovered Yunlekenhalasu deposit in the porphyry copper belt ofHalasu-Hadansun in the northeast margin of Junggar has distinct Characteristics of porphyry mineralization, such as disseminated mineralization, simple metallic mineralassociation, mainly Chalcopyrite, pyrite, molybdenite and magnetite, and clear alterationzonation: from the central to the external are belts of potash feldspathization,biotitization, sericite-quartz alteration, propylite alteration in succession.Zircon U-Pb dating of the two ore -bearing rock body, porphyritic granite and Beschtauite porphyry in Yuleken-Halasu deposit are 265.6±3.7Ma and 381.6±2.5Ma,respectively. The characteristics of the zircon which show its genesis was magmatic,together with the former research on chronology in Xilekehalasu, show that there weretwo periods for porphyry mineralization which are Early-Middle Devonian and Early Permian.Research on H-O isotope and fluid inclusion in Yuleken-Halasu deposit proves that metallogenetic fluid mainly derived from magmatic water and mixed with atmosphericwater latterly. The metallogenetic fluids with a small volume and a large quantity, have alarge range of halite (1.27~17.96wt%). Together with the ore relatively rich in magnetite,the metallogenetic fluids have some characteristics as follows: rich in water, andchlorine, as well as oxidation.δ34SV-CDT of the pyrite in Yuleken-Halasu deposit is -3.795‰~-1.766‰, andεNd(t)and (87Sr/86Sr)I of the whole rock are 12~12.5 and0.70343~0.70423,respectively, which proves that the source of the mineralizationderives from mantle. Porphyritic granite in the mining area shows that it was Island-arc background in Middle Devonian and the outcrop of thick-layered picrite implies that there exists micro rift which made the mantle-derived material uplift. The trace element characteristics ofthe beschtauite porphyry, as well as the basic rock of the internal and external area in the same stage show that the rock in this area forms at Early Permian when the newcontinental crust was in the condition of extension. High-grade ore body of the local quartz veins may be the result of tectonic - magmatic activity in the Indo-Chinese epoch.The characteristics of the superposition of the multistage metallogenesis in MiddleDevonian, Early Permian and Triassic is similar to that of the typical mineralization inthe Central Asia - Mongolia metallogenic domain, which is mainly inheritance and transformation of the previous ore-forming materials and superposition of the newlyore-forming materials. Both this and Southern Mongolia metallogenic belt ,in themagmatic island-arc belt ,are located in the southern margin of arc-shaped deep and large fault and both are in the dividing line of the Late Paleozoic uplift and Mid-Cenozoic depression. Therefore this mining area belongs to the part of Western extension part ofthe South Mongolia metallogenic belt.Based on the study of the strata, structure and geochemical exploration, the closed condition of the country rock in the northern part is better than the others making itpreferential to form porphyry copper deposit, and the little erosion helped preserve themine which made the Contiguous zone of Xi-Yu become a preferential area for the exploration of the porphyry copper deposits. Together with the analysis of nature of theN-S strike fault, the west of Aoertahalsu is another area for the exploration of theporphyry copper deposits. Synthetic study of the geological, geophysical, and geochemical data, shows that the preferential area of the exploration of structural alteredrock type deposits is located in the central part of the mineralizing belt and magmatictype deposits have a large possibility to form in the south.