Abstract:With the deepening of the exploration and research of sandstone-type uranium deposits in southwestern Songliao Basin, the understanding that construction skylight serves as a local excretion source has obvious effects in guiding prospecting. However, the internal relationship between local excretion source and uranium mineralization is relatively weak at this stage, especially the internal connection between the local excretion sources and the spatial positioning of uranium deposits and whether it is related to the formation of unique geological phenomena such as tabular orebody, double-layer oxidation and gray residual body. Therefore, this paper introduces the theory of groundwater flow system to explore the ore-controlling effect of local excretion source in sandstone-type uranium deposits in southwestern Songliao Basin. It is believed that the formation of the local excretion source of the Baixingtu construction skylight changed the original supplemental – diameter - discharge system, so that there are two sets of local and regional groundwater supplement - diameter - discharge systems in the ore-bearing layer and formed relative stagnation zone near the local excretion source. The local excretion source mainly affects the development speed and position of the interlayer oxidation zone by changing the transport direction and speed of the uranium and oxygen groundwater, thereby controlling the formation of tabular orebody, double-layer oxidation and gray residual body in the ore-bearing layer and the spatial positioning of uranium deposits. Based on this, the sandstone - type uranium metallogenic model and prospecting model in southwestern Songliao Basin were established, which not only enriched the sandstone-type uranium metallogenic theory, but also pointed out that in addition to continuing to carry out exploration work around the construction skylight, looking for uranium deposits controlled by regional interlayer oxidation zones may be a new breakthrough in the expansion of uranium resources in the study area.