Geochemical characteristics of trace elements and Rare earth elements in Permian Lucaogou oil shale,Santanghu Basin

The Permian Lucaogou Formation oil shale in Santanghu Basin was developed near the Shitoumei uplift,lo- cated in the southwestern margin of the Santanghu Basin. The geochemical characteristics of trace elements and rare earth elements in the selected oil shale samples from the Santanghu area were measured by using inductively-coupled plasma mass spectrometer(ICP-MS)technique. The results show that the content of some elements,such as V,Cr,Ni, Cu,Ge,As,Se,Rb,Sr,Mo,Cd and Sb,in this studied area are higher than that in the Chinese coals,and also some toxic elements and Carcinogenic element (e. g. Cd,Ni,As,Cd) are obvious higher than that in the earth crust and the average content of the Chinese coals. The average contents of REE is lower than that in the North American Shale Composite (NASC),and the REE distribution patterns shows that the samples of the selected area has an obvious en- richment of the light rare earth elements (LREEs),than that of the heavy rare earth elements (HREEs),with Eu fre- quency changes with depths,reflecting a strong fractional degree among LREEs and a slight fractional degree among HREEs. On the whole,the value of δCe,δEu,Sr / Ca,Sr / Ba,V / ( V+Ni) and V / Cr indicate that the oil shale in this area was developed in oxygen poor to deficit condition,and reflect that the oil shale in this area was deposited in a rel- ative deeper-water environment with salinity water.