Application of Rare Earth Elements of the Marine Carbonate Rocks in Paleoenvironmental Researches

The pattern, contents and ratios of Rare Earth Elements (REE) from marine carbonates play an important role in the paleo-environmental researches. As result of the REE's source being variable, which includes marine carbonates, detrital input and diagenesis, the overall assessment for the reliability of REE's data is necessary. Furthermore, appropriate analytical method is vital for the reliable contents of REE. This paper reviewed the geochemical properties, analytical and data processing methods, feasibility verification and paleo-environmental application of carbonates REE. The patterns of REE, which provide theoretical basis for the provenance and depositional environment of carbonates, are various with different sources. Cerium, as a redox sensitive element, is a key proxy for the reconstruction of paleo-redox conditions. There are two available analytical methods, acid-leaching method and direct LA-ICP-MS analytical method, to extract REE of seawater preserved in marine carbonate rocks. The contamination from detritus and diagenetic alteration can be detected by the correlations of various elements or element ratios. The REE of marine carbonate has been well applied to reconstruct the environment changes during the Precambrian, Permian-Triassic transition and Cenozoic.