2026-10-10T07:19:09Z https://data.mendeley.com/oai

oai:data.mendeley.com/fpjcyc9jth.2 2026-09-14T09:46:33Z

Löhr, Stefan Chemical Weathering Influence on the Rare Earth Element Chemistry of Phosphorites Mendeley Data Phosphorites are important sedimentary archives of Earth system evolution and biospheric change. They are also increasingly considered a promising source of rare earth elements (REEs). The mechanisms governing phosphorite REE chemistry are complex and not well understood, particularly the impact of weathering. Here we investigate how chemical weathering and secondary mineral formation influence REE systematics and concentration in a weathering profile developed in Cambrian phosphorites of the Georgina Basin (Australia). Our results show that the total REE and Y content of weathered Beetle Creek Formation phosphorites (up to 7600 ppm) is at least ~2-3 times greater than of unweathered phosphorite from the same unit. In unweathered phosphorite, REEs are largely hosted within carbonate fluorapatite. Similarly, apatite is the dominant REE host phase through the majority of the weathered phosphorite, but with increasing contributions by bastnäsite and crandallite-group minerals (crandallite, gorceixite and goyazite) up the profile. Crandallite and bastnäsite are the dominant REE carriers in a narrow, heavily weathered transitional interval between the phosphorite unit and overlying shales. Both weathered and unweathered phosphorites show heavy REE-enriched patterns. However, laser ablation and sequential leaching analyses confirm that crandallite preferentially incorporates light REE, contributing to heightened light REE depletion and mid to heavy REE enrichment in secondary, weathering-derived apatite. Uptake of heavy REEs by secondary xenotime is responsible for depletions in Gd-Lu in secondary apatite. Although we infer that REE enrichment due to chemical weathering is mostly achieved by internal redistribution within the phosphorite, shifts away from marine Y/Ho and Ce/Ce* values in secondary apatite imply an input of REEs sourced from weathering of siliciclastic units overlying the phosphorite. We conclude that chemical weathering can increase the REE content of phosphorites and substantially modifies the REE systematics of secondary apatite, although this likely depends on weathering intensity. Consequently, palaeoenvironmental interpretations based on REE data from potentially weathered phosphorites should be treated with caution. We further suggest that the overall impact of weathering is beneficial from an economic geology perspective, so that weathered phosphorites merit increased attention as exploration targets. This dataset includes major and trace element data from sequential leaching (solution ICP-OES and ICP-MS) and from in situ analysis (EMPA and LA-ICP-MS) of weathered and unweathered phosphorites of the Cambrian aged Beetle Creek Formation, Georgina Basin, Australia. Quantitative mineralogical data from X-ray diffraction analysis are also included. Mineralogy Low-Temperature Geochemistry Chemical Weathering Apatite Elemental Geochemistry Mineral Chemistry Weathering Profile Zivak, Diana Spandler, Carl Baldermann, Andre Dataset doi:10.17632/fpjcyc9jth.2 oai:data.mendeley.com/fpjcyc9jth.2 Creative Commons Attribution 4.0 International http://creativecommons.org/licenses/by/4.0 https://data.mendeley.com/datasets/fpjcyc9jth 2026-09-14T09:46:33Z