Post-phosphogenesis processes and the natural beneficiation of phosphates: Geochemical evidence from the Moroccan High Atlas phosphate-rich sediments

• Published in: Chemical geology 2023-08, Vol.631, p.121523, Article 121523
• Main Authors: El Bamiki, Radouan, Séranne, Michel, Parat, Fleurice, Aubineau, Jérémie, Chellaï, El Hassane, Marzoqi, Mohamed, Bodinier, Jean-Louis
• Format: Article
• Language: English
• Subjects: Environmental Sciences; Geochemistry; High Atlas; Morocco; Phosphate; Reworking; Upper Cretaceous-Paleogene; Weathering; Winnowing
• ISSN: 0009-2541
• DOI: 10.1016/j.chemgeo.2023.121523

The Upper Cretaceous-Paleogene sedimentary series of the High Atlas hosts underexplored phosphate-rich sediments and presents an excellent example of how complex interactions between various geological processes control the accumulation and distribution of phosphates. Genetically-linked phosphatic lithofacies from this series were investigated for their mineralogical and geochemical compositions with the purpose of assessing the impact of post-phosphogenesis sedimentary processes on the geochemical behavior of genetically-linked phosphatic lithofacies and understanding the distribution of chemical elements. Sampled phosphatic horizons from five representative sections along the Marrakesh High Atlas borders were investigated using optical and scanning electron microscopies (OM and SEM), X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), and inductively coupled plasma mass spectrometry (ICP-MS) techniques. Results indicated that the studied lithofacies are composed of a mixture of phosphatic and non-phosphatic particles in variable proportions depending on the facies type. However, the phosphatic fraction is dominated by carbonate fluorapatite (CFA), showing an average CO32− content of 8.40 ± 0.37 wt%. Geochemical results revealed variations in the chemical composition of the different phosphate facies. Low-grade pristine phosphatic sediment (P2O5