The elemental geochemical characteristics of aluminous argillites in Taiyuan Formation from Huainan coalfield

Aluminous argillites are widely deposited in the Late Carboniferous to Early Permian Taiyuan Formation of Huainan coalfield at the southeast margin of the North China Plate. However, knowledge about their formation conditions and geochemical characterizations are not presently known. We collected samples from a borehole in Zhangji coal mine and tested their geochemical parameters, including major and trace elements, by XRF and ICP-OES and ICP-MS, respectively. The geochemical characteristics and geological origin of Huainan aluminous argillites were investigated. Results show that:nearly all the argillites have comparable ratios of SiO₂/Al₂O₃ and Fe₂O₃/Al₂O₃, suggesting that they were possibly derived from the same source materials, however, bauxitic argillites significantly deviate from the correlation slopes, indicating that they probably suffered a more extensive laterization than aluminous argillites; the Sr/Ba ratios of the studied argillite sam-ples were possibly deposited in an unstable paleodepositional environment, while the V/Cr and V/(V+Ni) ratios suggested an anoxic environment; based on the comprehensive consideration of major and trace element results, the studied aluminous argillites probably derived from the common parent rocks composed of felsic to intermediate igneous rocks. These argillites were presumably deposited under anoxic environments in Huainan area.