Phosphorus, phosphorites and marine authigenesis -sedimentology, geochemistry and environments of formation
The session focus will be on the stratigraphy, sedimentology, petrography,mineralogy and geochemistry of phosphatic sediments and associated authigenic mineral deposits. Depositional models and diagenetic studies of phosphorites, glauconies and other iron minerals, barite and clay minerals should be included. Laboratory and field experiments, and observations of modern phosphogenesis and other authigenic mineral systems might be discussed. The formation of phosphatic sediments in upwelling systems, oceanic islands, atop seamounts, guyots, plateaux, shelves, slopes and in epeiric environments are of interested. Sources of phosphorus and geochemical modeling of nutrients and allied element cycles at all scales, from local to global, should be considered. Applications of trace element and isotopic studies, particularly the use of novel isotope systems to constrain authigenic processes, are particularly sought. Topics might additionally include: environmental issues associated with excess phosphorus concentrations in water and sediment; the nature and origin of currents that play important roles in many phosphorite deposits, including condensation, concentration and redeposition as turbidites and tempestites; relationships between authigenic mineral formation, sea-level change and sequence stratigraphy ; the relative importance of biological/microbial versus inorganic processes during carbonate fluorapatite precipitation at the sediment/water interface, within the sediment column, and/or during later burial diagenesis ; phosphorus and authigenic mineral distributions in the geological record and their potential as palaeoevironmental proxies.
El Hassane Chellai and Ian Jarvis