A brief analysis on the three-dimensional geological structure and uranium mineralization of Jurassic uranium-bearing rock series in the northeastern Ordos Basin

This paper is the result of mineral exploration engineering.

Objective In order to more intuitively and accurately reveal the three-dimensional spatial distribution of the Jurassic uranium-bearing rock series (the Zhiluo Formation) in the northeastern margin of the Ordos Basin, the research on the uranium metallogenic characteristics and the prospecting and prediction work were carried out.

Methods In this paper, we used the first established comprehensive database consists of drills, logging to construct the three-dimensional geological models with different scales and types and realized its visualization function in the Dongsheng uranium area.

Results and Conclusions Comprehensive geological modeling shows that uranium mineralization in this area has the following characteristics: (1) Under the influence of the paleogeomorphic pattern of "high in the north and low in the south, high in the east and low in the west" during the depositional period of the Zhiluo Formation, there was a regional sedimentary facies transition in the lower section of the Zhiluo Formation in the Nalinggou-Daying area. From the northern Husliang-Tanggongliang paleo-uplift area to the west and south, the sedimentary system gradually changed from alluvial fan-gravel braided river to sandy braided river and braided river delta deposition. Uranium mineralization in Daying area is concentrated in the distributary channel of braided river to braided river delta, while uranium mineralization in Nalinggou is mainly in the sandy braided river which was above the gravel braided river; (2) The heterogeneity of uranium reservoir in the lower member of Zhiluo Formation increased from Husiliang in the east to Daying area in the west, which is manifested as a significant reduction in the thickness of the sand body, a decrease in the sand content ratio, a significant increase in the number and thickness of mudstone layers, and the inner coal-line began to develop. The occurrence of above combination formed a large-scale lateral argillaceous barrier layer and vertical reduction layer on the west side of Daying, which greatly inhibited the westward propulsion rate and distance of the interlayer oxidation zone. Therefore, a stable front line of interlayer oxidation zone and continuous uranium mineralization are formed in the Daying area; (3) By the three-dimensional geological modeling of ore deposits, it can be found that the arc-shaped uranium mineralization body in Daying area is almost connected with the uranium mineralization in Nalinggou- Tanggongliang. Meanwhile, the three-dimensional γ property model between the two deposits also shows strong radioactive, which indicate that the Tarangaole- Wudingbulage area between Daying and Nalingou diposits has a good prospecting potential.