Study On Metallogenic Conditions Of Upper Cretaceous System For In-situ Leachable Sandstone Type Uranium Deposit In South Songliao Basin

mineralization. The explored deposit and uranium prospects distributes at the sides of deep faults or fault-intersected areas.The paleo-climate after Quantou Formation underwent changes from semiarid to warm damp,arid, semiarid.These changes are favorable for interlayered oxidation. Quantou Formation and Yaojia Formation developed braided stream and delta facies which are favorable for uranium mineralization. Thick Sandstone bodies in Quantou Formation and Yaojia Formation developed at the southern and southwestern margin of the basin.The favorable alteration such as oil-gas epigenetic reduction, clayzation, interlayered oxidation for uranium mineralization developed widely in Yaojia Formation,but epigenetic reduction did not develop in Quantou Formation,only epigenetic oxidation developed at different extent. Quantou Formation and Yaojia Formation exposed on the surface and received infiltration of atmospheric precipitation since early Paleogene. Initial content of organic carbon in Yaojia Formation is low,but underlying oil-gas can uplift and penetrate sandstone of Yaojia Formation and make up for reducing agent shortage. In conclusion, Yaojia Formation is chosen as first target explorating layer and Quantou Formation as secondary target layer.Ore bodies in Qianjiadian uranium deposit occur in lathlike,lensoidal shapes and uranium mineralization exists in gray sandstone.in the form of adsorption and isolated uranium mineral. Epigenetic alteration in Yaojia Formation are mainly oil-gas epigenetic reducing fading alteration, clayzation, carbonatization, interlayered oxidation.Fluid inclusion indicates multiphase oil-gas exudation developed in South Songliao basin and a number of gas-liquid hydrocarbon,gas hydrocarbon and saltwater inclusion exist extensively in ore-bearing and country rocko The results of temperature and salinity measuring indicate that extracting fluid has higher temperature and mineralization degree.There are two groups of uranium metallogenic age,the main metallogenic age,53Ma, corresponds to the period of structure inversion and large-scale uplift and erosion,the second metallogenic age,7Ma, post mineralization superposed reconstitution, corresponds to whole basin uplift and differential subsidence period.The uranium ore-controlling factors are deep seated faults,invision structure, fault depression with rich reducing fluid, braided stream and delta facies, geochemical barrier. Uranium metallogenic modal of Upper Cretaceous system is summarized as:uranium pre-enrichment caused by ore host rock in late cretaceous epoch, uranium extraction by deep source fluid exudation and mineralization during the end of late cretaceous epoch to Paleogene Period, epidiagenetic oxidation transformation and uranium superimposed reconstitution in hydrothermal activity at the end of Paleogene Period to Neogene Period.The main uranium exploring type is oil-gas extraction and interlayered oxidation superposed type. Uranium exploration guides are regional active faults, denudation exposed areas,deep extension with rich reducing fluid, braided stream and delta facies, uranium anomalies and prospects at the surface or mineralization drill holeThe Southwest and southeast Songliao basin are most favorable areas for in-situ sandstone uranium deposit, Chaolutou-Hulihai and Jinbaotun-Kangping first-level prospect section, Wushijiazimiao-Xiaojieji and Yangdachengzi-Huaide second-level prospect sections.