The distribution and behavior of iron in sequences of dolomites, clays and oxides

Marly beds, containing Fe²⁺- and Fe³⁺-bearing kaolinite and iron oxides in the form of akaganeite and hematite are found, interbedded with Fe²⁺-containing dolomites and pure kaolonite in the Jurassic Ardon Formation, Makhtesh Ramon, Israel. The envisaged reactions leading to the formation of these assemblages are: (1) intensive leaching in a tropical environment, leading to the formation of Fe-rich kaolinites and iron oxides; (2) deposition in a calcium chloride brine environment, reducing in its lower part; and (3) reduction and leaching of Fe in the reducing zone and redeposition in the oxidizing upper zone.