2D and 3D Seismic Survey for Sandstone-Type Uranium Deposit and Its Prediction Patterns, Erlian Basin, China.

The Erlian basin is one of the most important basins in northern China to host sandstone-type uranium deposits (SUDs), in which Bayanwula, Saihangaobi, and Hadatu are under development, to name a few. Issues such as the metallogenic mechanism and mineralization of these deposits need to be addressed throughout the mining process. Over the past several decades, 2D and 3D seismic reflection surveys have been carried out to study these typical SUDs. The seismic technique has become the most effective geophysical tool of uranium (U) exploration, and it is used to develop our understanding of the stratigraphic configuration, faults, and sandstone contents of target layers in uranium environments. In addition, seismic interpretation could yield useful suggestions regarding the subsequent drilling program in the work area. There are two seismically predictable patterns of SUDs, named "Big depression + fault" and "Large-angle unconformity + fault", which have been established following detailed seismic research in this basin. The characteristics of these faults are as follows: (1) the "'U'-shaped formation" is conducive to the inflow of O-U-bearing groundwater into the target sandstone; (2) the "Big depression of reductive formation" provides plenty of organic matter (containing reducing media and U pre-enrichment) to promote redox reaction mineralization; (3) "Large-angle unconformity" is favorable to the migration of reducing substances, consequently leading to an enhancement in redox U mineralization; (4) "faults with long-term activity" become rising channels for reducing the presence of fluids and gases at depth; and (5) "sandstone and its scrambled seismic facies". The results also offer indirect evidence of a connection between hydrothermal fluids and U mineralization; a hypothesis of "hydrothermal effusion" mineralization is proposed accordingly. In conclusion, seismically produced images of geological structures and sandstone distribution could yield important information for U prospecting and mine planning; it is worth considering seismic technologies in the future exploration of SUDs. [ABSTRACT FROM AUTHOR]