Sedimetology and magnetic susceptibility of Mobarak formation (Lower Carboniferous in central and eastern Alborz Mountains, North of Iran).

The Mobarak formation (lower Carboniferous) corresponds to a carbonate platform which was located in the northern margin of Gondwana. This work is focused on the two stratigraphic sections located in central and eastern Alborz Mountains: the Aruo and Shahmirzad sections. Palaeoenvironments are corresponding to a carbonate ramp platform with frequent storm deposits. Different facies have been observed and are from proximal to distal: (1) crinoid banks and lagoonal facies with abundant peloids and oncoid; (2) in-situ bioherms, mainly constituted by accumulations of tabulate corals, shell fragments and crinoids steams; (3) distal to proximal tempestites and (4) bioturbated dark argillaceous mudstone. The main sedimentological evolution is a shallowing-upward trend corresponding to the transition from distal to proximal tempestites, bioherms, crinoids banks and lagoonal facies. Magnetic susceptibility data are also provided in order to get a better understanding of sedimentary dynamics and correlation between the two sections. It appears that MS values are the lowest for the more energetic environments which corresponds to the trends observed in the Devonian carbonate ramp in Belgium