Mineralogical and Geochemical Characteristics of Late Permian Coals from the Mahe Mine, Zhaotong Coalfield, Northeastern Yunnan, China

Abstract

This paper reports the mineralogical and geochemical compositions of the Late Permian C2, C5a, C5b, C6a, and C6b semianthracite coals from the Mahe mine, northeastern Yunnan, China. Minerals in the coals are mainly made up of quartz, chamosite, kaolinite, mixed-layer illite/smectite (I/S), pyrite, and calcite; followed by anatase, dolomite, siderite, illite and marcasite. Similar to the Late Permian coals from eastern Yunnan, the authigenic quartz and chamosite were precipitated from the weathering solution of Emeishan basalt, while kaolinite and mixed-layer I/S occurring as lenses or thin beds were related to the weathering residual detrital of Emeishan basalt. However, the euhedral quartz and apatite particles in the Mahe coals were attributed to silicic-rock detrital input. It further indicates that there has been silicic igneous eruption in the northeastern Yunnan. Due to the silicic rock detrital input, the Eu/Eu* value of the Mahe coals is lower than that of the Late Permian coals from eastern Yunnan, where the detrital particles were mainly derived from the basalt. The high contents of Sc, V, Cr, Co, Ni, Cu, Ga, and Sn in the Mahe coals were mainly derived from the Kangdian Upland.

Mineralogical Characteristics of Late Permian Coals from the Yueliangtian Coal Mine, Guizhou, Southwestern China

“…Although the thick lava sequence from the Emeishan large igneous province in southwestern China is basalt, silicic rocks also occur in the uppermost part of the Kangdian upland [47]. There is no quartz and apatite in Emeishan basalt of the Kangdian Upland [49]; the abundant detrital quartz (Figure 5B-D) and authigenic apatite ( Figure 13H) probably indicate that the parent rock is also granite or other silicic rocks [47].…”

“…There is no quartz and apatite in Emeishan basalt of the Kangdian Upland [49]; the abundant detrital quartz (Figure 5B-D) and authigenic apatite ( Figure 13H) probably indicate that the parent rock is also granite or other silicic rocks [47]. …”

“…The abundant authigenic quartz ( Figure 5A) is probably precipitated from the silicious solution of the weathering product of Emeishan basalt from the Kangdian Upland [47,54]. Epigenetic vein-like calcite ( Figure 6D) is probably precipitated by the circulation of Ca-bearing meteoric fluids or by Ca-rich solutions during the coal-formation process [55].…”

“…Quartz in the YLT6 coal is slightly higher than that in coals from the Dafang (0.8%-11.4% on average) [14] and Zhijin (0.5%-9.4% on average) mines [35] (Figure 1), consistent with Dai et al [15] and indicating that the closer the coals are located to the sediment-source Kangdian Upland region, the higher the quartz in the coal. The abundant authigenic quartz ( Figure 5A) is precipitated from the silica-bearing solutions from the weathering of basalt in the Kangdian Upland [15,47,48].…”

The Fate of Trace Elements in Yanshan Coal during Fast Pyrolysis

“…There are many studies on the concentration, geochemical, and mineralogical characteristics of TEs in coal [4][5][6][7][8][9][10]. For example, Dai et al [11] investigated mineral composition and the TE concentrations in coal from the Huayinshan coalfield.…”