NEW INSIGHTS ON MESOZOIC DEPOSITIONAL SEQUENCES AND HYDROCARBON SYSTEMS, FROM JIFFARAH ESCARPMENT TO LIBYAN OFFSHORE BASINS

Abstract

This paper provides the results of outcrop data analyses across the Jiffarah Escarpment 
(JE). A new Mesozoic stratigraphic scheme and sequence stratigraphic framework are proposed which 
could be used both in the Libyan onshore and offshore. Chronostratigraphic chart has been constructed 
across the JE, in E-W direction. The chart demonstrates the way in which depositional sequences and 
sedimentation history vary across the JE via time. The exposed stratigraphic succession at JE ranges in age 
from Middle Triassic to Late Cretaceous. This Mesozoic succession represents two second-order sequences 
(Triassic to Middle Jurassic; and Cretaceous), both depositional sequences are bounded by major tectonic 
unconformities. The lower sequence (SI) is bounded by the Hercynian unconformity at the base of the 
Triassic and MFS of SI is placed in the Bathonian. The Cretaceous sequence (SII) is bounded by the 
Cimmerian-Austrian unconformities at the base and the Albine unconformity at the top. Deposition of the 
JE Mesozoic mega-sequences took place during several rifting phases effecting the Mediterranean basins, 
starting from Triassic and passing through the Jurassic and terminated during Early Cretaceous. The region 
witnessed compressional phases during the Albine Orogeny which lead to uplifting and erosion of wide areas 
along northern African margin. Stratigraphic correlations made on Mesozoic sequences reveal a complex 
sequential organization and also account for the impact of the Hercynian uplift and paleotopography on 
eastward truncations of Triassic-Middle Jurassic sequence. Post Albian deposits developed on a smoothed 
topography associated with a regional transgression and can be easily correlated over the JE. Reservoir and 
source rocks potential of the outcropping Triassic-Cretaceous sequences along JE reveal the importance of 
the deeper thermogenic petroleum systems located in the subsurface of the adjacent Gabes-Tripoli Basin. 
The exposed Miocene sequence along eastern JE represent good analogue to the proven biogeneic Neogene 
gas system in the adjacent Mediterranean basins and support the assumption of discovering similar plays in 
the Libyan offshore basins.