Enrichment and Origin of Some Trace Elements in Black Shales from the Early Cambrian in Eastern Guizhou Province

The analysis is based on the elemental geochemistry, ¹³C, ¹⁸O isotope and lithology combination of the black shale, a set assemblage mud and carbon of lithology , in East Guizhou. The coordinated change in spider diagrams of race elements suggests those elements have the same source. The ¹³C, ¹⁸O isotopes, mode of REE partition and characteristic enrichment of elements assemblage in carbonaceous shale show that the deep thermal fluid is added, and the shelf sea basin edge with distribution of hydrothermal activity is propitious to precipitation of ore elements. Evidence from the ³⁴S isotope and redox-sensitive elements show that the hydrostatic hypoxia environment is also conducive to precipitation of elements. The lithologic features (phosphorus, coal-bearing layers) and high content of organic carbon indicate that the deposits are influenced by the upwelling ocean current.