Sirte Basin - Geologic Setting

Geologic Setting

The Sirte Basin province is considered to be a type locality of a continental rift (extensional) area and is referred to as part of the Tethyan rift system. According to the designation scheme of Bally and Snelson, it is classified as 1211; a cratonic basin located on earlier rifted grabens on a rigid lithosphere and not associated with formation of megasutures. Clifford terms it as an interior fracture basin near the tectonic plate margin, which characteristically has an axis at an angle to that margin.

The area's structural weakness is exemplified by alternating periods of uplift and subsidence originating in the Late Precambrian, commencing with the Pan-African orogeny that consolidated a number of proto-continental fragments into an early Gondwanaland. Rifting commenced in the Early Cretaceous, peaked in the Late Cretaceous, and ended in the early Tertiary, resulting in the triple junction within the basin. The Late Cretaceous rifting event is characterized by formation of a sequence of northwest-trending horsts and grabens that step progressively downward to the east; the Sirte Trough represents the deepest portion of the basin. These horsts and grabens extend from onshore areas northward into a complex offshore terrane that includes the Ionian Sea abyssal plain to the northeast. This plain is underlain by oceanic crust that is being subducted to the north and east beneath the Hellenic arc. The Pelagian province to the west, particularly the pull-apart basins of the Sabratah Basin and extending along the South Cyrenaica Fault Zone (SCFZ) and the Cyrenaica Platform to the east, is strongly influenced by extensional dextral strike-slip faulting. To the south, the Nubian Swell is the stable continental basement for this rifted basin.