The shell beds in the Ziarat Formation (Middle Eocene) have been distinguished into primarySokolowia biogenic, fair-weather wave and proximal storm tempestite concentration of varied taphonomic and sedimentologic characteristics. The existence of normal grading, sharp and erosional base in the uppermost part of the Ziarat Formation indicate proximal tempestites between the storm wave-base and fair-weather wave-base. Disarticulated and intensely fragmented shells were concentrated above the fair-weather wave-base. These are convex-up, exceedinglySokolowia fragmented; poorly sorted large shells in calcareous marl were formed under strong hydrodynamic energy above the storm weather base. Articulated shells in silty mudstone matrix, without fragmentation and abrasion, were accumulated in lagoon environment attributing to in-situ concentration. These shell concentrations are recognized in distinct positions within the depositional sequence of the Ziarat Formation.
