Occurrence regularity and controlling factors of gallium in coal of Nanwu mining area, Chongqing

The Upper Permian Longtan Formation is the main coal-bearing rock series in Nanwu mining area of Chongqing. Based on the survey and sampling, ICP-MS (rare earth element), electron microscope and X-ray diffraction, the elemental geochemical characteristics were studied. It is found that the element Ga in seam C₂₅ of Late Permian Longtan Formation in Nanwu mining area is enriched, showing the variation pattern of being high in the northeast and low in the northwest in the plane. In Tianbao coal mine in the northeast of the mining area, the coal mine has reached comprehensive utilization grade, the value of comprehensive utilization of metallic elements deserves attention. SPSS statistical analysis showed that Ga in C₂₅ exists mainly in the inorganic state in clay minerals or aluminum silicate minerals. The preliminary analysis shows that the Ga accumulation in the Late Permian Longtan Formation in Nanwu mining area is controlled mainly by provenance, sedimentary environment and tectonic thermal evolution.