Research progress and prospects on the dating of pelagic clay

Pelagic clay, which is extensively distributed in the ocean basins below the carbonate compensation depth, exhibits slow sedimentation rate and contains only a small amount of preserved biogenic components (primarily biogenic apatite). The commonly used dating methods that combine magnetic stratigraphy with biostratigraphy in marine sediments cannot be effectively applicable. As a result, the establishment of a age framework for pelagic clay has been hindered by enormous difficulties and challenges, which seriously limits the researchers in geoscience to thoroughly investigate the evolution of sedimentation environment and the mechanisms of hyper-enrichment in rare earth elements in pelagic clay. In this article, we reviewed various dating methods for pelagic clay used since the last century, including mainly: magnetostratigraphy, fish teeth ⁸⁷Sr/⁸⁶Sr dating, fish teeth U-Pb dating, ¹⁰Be dating, ²³⁰Th_ex dating, ¹⁸⁷Os/¹⁸⁸Os dating, ichthyolith biostratigraphy, constant Co-flux model, and commonly used stratigraphic correlation methods. Each method has own advantages and disadvantages, and it is often difficult to acquire a complete and reliable age framework using any of the above methods alone. Consequently, systematic comparsion and validation for age framework obtained by intergrating multiple dating methods will be more efficient in improving the relability of an age framework for dating pelagic clay.