Characteristic and geological significance of trace elements in mudstone of Upper Carboniferous-Lower Permian in Linxing area

Trace elements of 18 mudstone samples of Linxing area in the eastern margin of Ordos basin were analyzed using ICP-MS and ICP-AES to study geochemical characteristics and the geological application of trace elements. The results show that compared with elements' average content of the crust clay rock, some trace elements such as Li, Sc, Nb and Th are relative enriched, depleted elements such as Sr, Rb, Ba and Cs are almost in line with them such as Be, Co, Zn and Mo; based on statistics software "Q" cluster analysis, the combinating characteristics of trace elements coincide with sedimentary facies division when the clustering distances are 25 and 11; Th/Sc, Th/U-Th, K₂O-Rb and multielements provenance discrimination diagram show that sediment source from upper crust mostly consist of felsic material and cyclic sedimentation, mixed with few neutral and basic material. In addition, the direction of source is the north of Linxing area according to the changing sand-bearing ratios and the distribution characteristic of the heavy mineral combination; the element migration and enrichment which were indicated by Sr/Cu, Sr, Ti and P reflected that the climate from Late Carboniferous to Early Permian was relatively wet, changing from warm-humid to dry-heat.