Catagenesis and Rare Earth Element Geochemistry of Phosphorites from the Cambrian Kuonamka Formation, Siberian Platform

摘要

Rare earth elements are common components of marine phosphorites, where they substitute for calcium [1]. Their content in the phosphorites averages 736-800 ppm [2, 3] ranging from 117 to 1470 ppm [2]. According to various authors, these variations depend on the following factors: the petrogrphic type of phosphorites, the characteristics of sedimentation basins and position of phosphorites in them, the role of aqueous and terrigenous constituents and organic complexes, the intensity of fecal material supply, the diagenetic transformation of primary phosphates, phosphorite age, and weathering [3-26]. One of the least studied aspects is the possible infuence of catalgenesis on REE abundance in phosphorites. This process strongly affects the contents of many minor isomorphous components in sedimentary apatite (carbonapatite). The possible effect of deep burial of phsophorites on their REE distribution patterns was suggested only by McArthur and Walsh [19]. The aim of htis paper is to approach this problem using the REE distribution in of the Siberian Platform as an example.