--> --> Uranium-Bearing Strata Sedimentary System and Uranium Mineralization in Fault-Depression Transition Stage: A Case Study of Tamusu Uranium Deposit in Bayingobi Basin

2018 AAPG International Conference and Exhibition

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Uranium-Bearing Strata Sedimentary System and Uranium Mineralization in Fault-Depression Transition Stage: A Case Study of Tamusu Uranium Deposit in Bayingobi Basin

Abstract

In China, the genesis of most sandstone-type uranium reservoirs belongs to braided stream sedimentary system and braided delta sedimentary system, which are characterized by uranium reservoir sandstone and interlayer oxidation zone (extending several hundreds of kilometers). The main cause of mineralization is that the uranium-bearing strata were all produced in a relatively stable period of basin tectonic evolution, which is basin margin thrust interval or faulted basin cracking thermal term. However, the sandstone-type uranium deposit, produced in faulted basin with strong tectonic activities especially under the background of fault-depression transition stage, has a great difference, where the uranium reservoir sandstone and its inner interlayer oxidation zone extend longitudinally shorter. Consequently, the volume of uranium mineralization is smaller. The difference of mineralization is actually caused by the special sedimentary environment of uranium-bearing strata, fan delta sedimentary system. The Tamusu uranium deposit of Bayingobi basin is a typical one of rare sandstone-type uranium deposits developed in faulted basins in fault-depression transition stage. According to the researches of tectonic-stratigraphic framework, sedimentary system, sedimentary background recovery, spatial configuration and models of genetic facies and functional analysis of sedimentary system in uranium mineralization process, the fundamental characteristic of this kind of uranium deposit has been clarified. Tamusu Uranium Deposit in Bayingobi basin in fault-depression transition stage has obvious characteristics revealed mainly including: Gravity flow sediments are more common exist in the uranium-bearing strata. The lake sediments are relatively developed and the energy of reducing medium is stronger, which restrict to the longitudinal scale of uranium reservoir sandstone and its inner interlayer oxidation zone (extend longitudinally no more than ten kilometers). The comprehensive research of sedimentary genetic indicators shows that the upper member of Bayingobi formation (ore-bearing horizon) was mainly marked by the progradational fan deltas in lakes and the paleoclimate of sedimentary period was relatively dry.