A sedimentological oxymoron: highly evolved glauconite of earliest diagenetic origin

This work examines the possibility of a rapid formation glauconite in relatively shallow platform environment (below fair-weather wave baseline). The materials studied here are uppermost Jurassic alternations carbonate beds and marly interbeds, namely, Assises de Croï Formation Boulonnais area (northernmost France). yield field evidences an early diagenetic origin both interbeds contain glauconite, questioning duration relative to that beds. Carbon oxygen stable isotope composition confirm growth. Contrasted grain-size distribution patterns quartz grain populations (isolated after acid digestion magnetic separation) evidenced formed sediment deposition. Glauconite allegedly requires protracted episodes ion capture from water column, which is no longer possible when gets trapped within authigenic carbonates. Therefore, in-situ preceded authigenesis. Yet, chemical grains (Fe K) typifies as highly evolved, meaning its must have lasted over times, according conventional views. Consequently, our results challenge these views can form environments (which has been already brought light previously) it concluded be markedly enriched K Fe, unprecedented result.