Rare earth elements in Late Precambrian phosphorites

Zhou Chuan-ming

pp. 197-204, in English

Abstract:

Rare earth elements (REE) concentrations in nine phosphorite samples and three phosphatic fossils, including two phosphatic acritarchs and one phosphatic oncolite form the Late Precambrian Doushantuo Formation in Guizhou Province were determined. The REE distribution patterns are similar to that of the sea-water and reflect the original REE signatures of the sea-water at that time. Cerium variations in phosphorites and fossil apatites are controlled by redox conditions. Weak to moderate negative Ce anomalies (0.543-0.805) and Ce/La ratio values (1.10-1.81) suggest that the original phosphogenic environment might be suboxic.

Keywords: Rare earth element, Phosphorite, Late Precambrian, Weng'an, Guizhou