A Deep Alteration and Oxidation Profile in a Shallow Clay Aquitard: Example of the Tégulines Clay, East Paris Basin, France

Figure 5

Calcite bioclast filled by diagenetic calcite and iron hydroxide (FeOx) replacing pyrite (AUB1010-4.80 m) (a) in transmitted light; (b) in BSE and (c) in chemical composite image (blue: Ca-rich, yellow: Fe rich; red: Si-rich); (d) bioturbation filled by pyrite (AUB1010-6.63 m) (transmitted light); (e) detail of pyrite partially replaced by iron hydroxides (BSE); (f) celestite partially filling zone of pyrite oxidation (BSE); (g) distribution of millimetric gypsum grains replacing pyrite layer in AUB1010-8.25 m (photo of the glass slide); (h) residual diagenetic pyrite and celestite surrounded by secondary iron sulfates, iron hydroxides, and gypsum.

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