| Uranium resources is not rich in china, which is in high demand because of the policies of energy conservation and emission reduction, and also for the development of nuclear power. Sandstone-type uranium deposit will be the main exploration type during a long period both at present and in the future in our country, for its characteristic of high resource, low development cost and slight pollution. To aim at this type of uranium deposit, a brand new train of exploration thought named "prospecting for coal mine and uranium deposit simultaneously" was born, which set off a rush to Sandstone-type uranium deposit exploration nationwide, reusing the coal drilling and logging material was its main method.The uranium resources in west Yunan province is comparatively rich, in that area, the lignitic drilling material of the Husa basin is full and accurate. Basing on the work of "prospecting for coal mine and uranium deposit simultaneously" in that basin, the conception of "the potential uranium reservoirs" was brought out for the first time in this paper, "the potential uranium reservoirs" is the clastic rock(layer) whose value of natural gamma-ray is over 50γ (or 3.5PA/kg or 150api or 12.6 (nC)/Kg-hour) in the coal drillng and logging material.40 layers of the potential uranium reservoirs in the first to the third member of the Mangbang Formation were found. Meanwhile, mainly on the core description and well-log analysis, combined with the outcrop observation, based on the throughly analysis of the sedimentary characteristic in the first to the third member of the Mangbang Formation, the types of the sedimentary facies about the potential uranium reservoirs were ascertained, the study shows that the alluvial fan facies, braided delta facies, fan-delta facies, lake facies and 10 types of subfacies,18 types of microfacies were developed in the first to the third member of the Mangbang Formation. And the braided channel sand body of braided delta front subfacies, the fan-delta front subfacies and the braided delta plain subfacies were main part whert the potential uranium reservoirs distribute. On the comparative sedimentary facies analysis of the connecting-well section, the distribution area of the sedimentary facies belt of the first to the third member of the Mangbang Formation and its potential uranium reservoirs were restored preliminarily. Research indicates that the alluvial fan facies and the braided delta facies were devloped in the gentle slope belt, the fan-delta facies were devloped in the steep slope belt, the lake facies were devloped in the depression belt in the central part of the basin, and the braided delta facies and the fan-delta facies were the most widespread facies during the depositional stage of the first to the third member of the Mangbang Formation.the potential uranium reservoirs were most probably distribute in the sand body of the fan-delta front facies in the steep slope belt and alluvial fan facies in the gentle slope belt.Base on above research results, comblind with the analysis of the tectonic setting, basin evolution, palaeoclimate, hydrogeology, lithological facies, deep uranium mineralization information and so on, study shows that the Husa basin possess relatively good mineralization potential of Sandstone-type uranium.and the first and second member of the Mangbang Formation were the main exploration layers, the fan-delta front subfacies and the fan-delta plain subfacies in the steep slope belt were first choice exploration sedimentary facies types, the root fan subfacies and mid-fan subfacies of alluvial fan in the gentle slope belt were second choice exploration sedimentary facies types, the deployment of exploration in the braided delta plain subfacies especially the the braided delta front subfacies zone need to be more cautious. |
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