Kaolinite is a common mineral found in most Chinese sandstone-hosted uranium deposits. It occurs particularly in coal-bearing clastic rocks in northwest China, such as the uranium deposits in the Yili Basin, which is well known for hosting several largescale roll-front uranium deposits. Previous studies have provided limited information on the origin of kaolinization and its role in the uranium mineralization. This study uses gas hydrocarbon, fluid inclusions, O and H isotope analysis, and scanning electron microscopy observations to investigate the formation of kaolinite in ore-hosting rocks from the Mengqiguer uranium deposit in the southern margin of the Yili Basin and to determine its role in the uranium mineralization. Results suggest that kaolinization is intense in the coal-and ore-bearing clastic rocks and that it is related to leaching of feldspar by acidic fluids. Vermicular kaolinite was formed by hydrocarbon-bearing fluid generated from coal and carbonaceous mudstone during a shallow-burial diagenetic stage at low homogenization temperatures ranging from 69 to 78 ∘ C and at relatively high salinities of 7.6−11.0 wt% NaCl eq . Consequently, silicate minerals (such as feldspar) were leached and created secondary pores that hosted the subsequently formed uranium minerals. In contrast, micritic kaolinite was formed by infiltration of meteoric fluid enriched in U and O 2 at low homogenization temperatures of 51−63 ∘ C and low salinities of 1.2−3.7 wt% NaCl eq . U 6+ was sorbed by the micritic kaolinite through cation exchange, forming a U-bearing kaolinite complex; it was also reduced by pyrite and carbon detrital, thereby precipitating at the acidic oxidation front. The results of this study confirm that intense kaolinization is closely related to uranium mineralization in coal-bearing clastic rocks.
Alagtaihert Al lies in the marginal areas of Altai which belongs to Mongolia. Mineral resources are rich, especially copper, and the degree of exploration is poor in this area. Based on the investigation and analysis about regional strata, geological structure and previous researches, it is considered that magma activity supplied sources of copper deposits and tectonic movement accelerated mineral dressing. Through electrical geophysical detection, it is indicated that the strike of copper belt is NNW, zonal distribution and sectional concentration are the characteristics about copper deposits. Combined geological and geophysical properties to present the metallogenic mechanics and model: Metal mineral crystallization was formed with metasomatism happened in hydrothermal process; the type of hydrothermal copper belt was formed far away from the rock after the period of pegmatite and gas-hydrothermal; the depth of copper deposits is about 300m and most of them were collected from 22 to 150m.
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