The Mineralization Of Sansheng W-Mo Deposit In Huade, Inner Mongolia

The W-Mo deposit of Sansheng village is located in Jining County, Inner Mongolia, which is a recent evaluation of medium-sized deposits, can go much further. Based on system research as follows:field geological investigation, mineral deposit geology, petrography, LA-ICP-MS zircon U-Pb and Molybdenite Re-Os chronology, element geochemistry, stable isotopes and fluid inclusions, this paper has discussed the molybdenum polymetallic mineralization and metallogenic mechanism, set up a metallogenic model of the W-Mo deposit. The granite bearing ore of Sansheng village is characteristics with high silicon, rich alkali, metaluminous to weakly peraluminous and high K calc alkaline/shoshonite series, indicates deep source of I type granite. The granite relative loss of Ba, K, Sr, P, Ti and other elements, show the mantle origin. The newly obtained LA-ICP-MS zircon U-Pb dating granite diagenetic age is137±IMa, early Cretaceous intrusive body. The ore-bearing sandstone and siltstone formation of Sanmianjing group show no obvious REE fractionation, slight enrichment of LREE, flat curve of HREE and there are K, P, Ti apparent loss. The andesitic porphyrite of Manitu group has a significant REE fractionation, enrichment of LREE, not obvious HREE fractionation. The tuff of Manitu group has a slight REE fractionation, which curve is flat. Eu appeared slightly enriched in both. Tuff and andesitic porphyrite show strongly loss of K, P, Ti. The Sansheng W-Mo ore body presents mostly stratiform, stratoid and lenticular formation, obviously controlled by magmatic rocks and structures. Vein type in the quartz and veinlet are the main ore types. According to the mineral assemblages we can divide into three stages of mineralization, quartz-wolframite stage, quartz-molybdenite-pyrite stage, quartz and carbonate stage. In the molybdenite-quartz veins there are mainly three types of fluid inclusions, which the rich liquid inclusions is most in common. Temperature of ore-forming fluid in main metallogenic stage is between200～290℃, the salinity of ore-forming fluid is5.00～8.95wt%, density of0.85～0.90g/cm3, the metallogenic pressure and metallogenic depth are6.12～16.49MPa and2.35～6.00km respectively. The lead-isotope composition of ore deviates significantly from the crust, the metallogenic substance mainly derives from deep source and orogenic belt, which also coincides with that granite derived from the deep source. The newly obtained accurate Re-Os dating of Molybdenite for metallogenic age from Sansheng W-Mo deposit is138±1Ma, shows that the area of molybdenum polymetallic deposits formed in the early Cretaceous, is in line with the main molybdenum deposits in the northern margin of North China block of large scale mineralization time (140Ma). This data of age almost equivalent to granite rock and ore within the error (the difference is only1Ma.), shows that the granite magma hydrothermal directly provides the source of metallogenic material. Sansheng W-Mo deposit metallogenic model presents as follows:in the late Yanshan phrase hydrothermal ore bearing solution took emplacement, in Sansheng granitic pluton and partly in sandstone, siltstone of Sanmianjing group and acidic volcano rock of manitu group, especially enriched in NNW fault forming tectonic fissures.