The research of petroleum exploration demonstrates that source rocks, developed in petroleum-bearing sedimentary basins worldwide, are accompanied by uranium to different degrees.As a special element with catalytic, oxidative and radioactive features, uranium may play important roles in the source rock formation and hydrocarbon generation. In this paper, we systematically discussed the formation conditions and main controlling factors of uranium in marine source rocks based on the comprehensive analysis of uranium contents in the worldwide source rocks and the interactions of uranium with minerals, organic materials and microbes. The results indicated that oxidative degrees of ancient atmosphere and palaeo-ocean were governing factors of uranium enrichment in source rocks. Oxidative weathering and hydrothermal solution might be the two main sources of marine sedimentary uranium. In addition, iron-bearing minerals, phosphate minerals, clay minerals, organic materials, and microbes were of great significance in promoting the transformation of the uranium valence states. They could also act as carriers to absorb or combine uranium, resulting in the enrichment of uranium in sediments. Therefore, the enrichment of uranium might be an inevitable result of source rocks formation. 相似文献
The Sichuan-Tibet railway goes across the Upper Jinsha River, along which a large number of large historical landslides have occurred and dammed the river. Therefore, it is of great significance to investigate large potential landslides along the Jinsha River. In this paper, we inspect the deformation characteristics of a rapid landsliding area along the Jinsha River by using multi-temporal remote sensing, and analyzed its future development and risk to the Sichuan-Tibet railway. Surface deformations and damage features between January 2016 and October 2020 were obtained using multi-temporal InSAR and multi-temporal correlations of optical images, respectively. Deformation and failure signs obtained from the field investigation were highly consistent. Results showed that cumulative deformation of the landsliding area is more than 50 cm, and the landsliding area is undergoing an accelerated deformation stage. The external rainfall condition, water level, and water flow rate are important factors controlling the deformation. The increase of rainfall, the rise of water level, and faster flow rate will accelerate the deformation of slope. The geological conditions of the slope itself affect the deformation of landslide. Due to the enrichment of gently dipping gneiss and groundwater, the slope is more likely to slide along the slope. The Jinsha River continuously scours the concave bank of the slope, causing local collapses and forming local free surfaces. Numerical simulation results show that once the landsliding area fails, the landslide body may form a 4-km-long dammed lake, and the water level could rise about 200 m; the historic data shows that landslide dam may burst in 2–8 days after sliding. Therefore, strategies of landslide hazard mitigation in the study area should be particularly made for the coming rainy seasons to mitigate risks from the landsliding area.