Author: Senusi M. HARSHA
Publishing Date: 2010
Volume: 25 Issue: 4
Two marines transgressive and regressive cycles are recognized during the Cretaceous time; one is represented during Early Cretaceous, when the Sirt area was still an arch. In this cycle, the sedimentation had only taken place on the line base of the arch. The Jurassic sediments partially transgressed the arch but had their depositional edge on the flank of the arch. The other cycle is represented after the northern Tibesti‐Sirt uplift collapsed in the beginning of the Early Upper Cretaceous and during the Upper Cretaceous (Campanian) time.
The Maestrichtian Sea encroached from the North and further to design the first flooding surface in the area. Thick of dark grey shale (Sirt Shale) followed by deposition of shallowing upward regressive carbonate of the Kalash Formation were deposited in the troughs. The Sirt shale acts as both a seal and source rocks for hydrocarbons trapped in the Cretaceous reservoirs and underlying the Cambro‐ Ordovician Gargaf Sandstone. The Upper Cretaceous formations are Bahi, Sirt, and Kalash in ascending order. The top of the Kalash Limestone marks the Maestrichtian/ Danian boundary in the study area.
Key Words: Sequence; Bahi; Sirt ve Kalash ; Sirt; Libya.