Paper Number
ICESET-23-134-10
www.medgu.org
Depositional sequence of Late Paleocene/Early Eocene Carbonate play system in North Sirt Basin
and Offshore Area, Libya
Mohamed Haman 1, Abdullatif Dugdug 2
1. Faculty of Science, University of Tripoli, Libya
2. Faculty of Science, University of Tripoli, Libya
S-N cross section shows Eocene nummulitic
NW reservoir in Subratah offshore basin.
SE
W-E cross section shows pinnacle reefs development of
Paleogene-Neogene carbonate shelfs in the southern
part of Ajdabiya Trough.
SB2
LST Wedge
TS
MFS
Geo-seismic cross section shows the sedimentary
fill of the offshore Sirt in Early cretaceous-Late
Eocene.
Late Paleocene-early Eocene seismic stratigraphy in
western Ajdabiya Trough.
Schematic S-N chronostratigraphic cross
section of Sirt Basin.
Schematic depositional model for the
Eocene section in eastern Ajdabiya flank.
Sirt Basin, time stratigraphic summery chart of
the Paleogene.
S-N cross section shows the presence of massive
slumps and slides in Eocene units on the flanks of
offshore Ajdabiya Trough.
Structure cross section shows potential charge
scenario in Offshore Sirt.
Conclusions
1. Late Paleocene–Early Eocene formations contain large volumes of oil and gas in Libya, particularly
in the North and east part of Sirt Basin and offshore area. They contain some excellent reservoirs
and regional seals, have attracted much exploration interest in recent years.
2. The Cretaceous- Paleocene boundary essentially marks the end of the syn-rift phase of the
development of the Sirt Basin and the commencement of the broad sag basin which dominates
the Tertiary.
3. There is evidence of atoll and lagoonal conditions during the Late Paleocene (early Thanetian),
which established the foundation on which the late Thanetian shoal accumulated in Sirt basin
and offshore area.
4. The Zelten reef complex is located on the northern edge of the shoal in north Sirt Basin.
5. In the northern Sirt Basin smaller carbonate shelves developed on the Waddan Platform and on
the Jahamah/Nuwfaliyah platforms.
6. In Upper Paleocene (Landenian), a group of pinnacle reefs formed in Middle to southern end of
the Ajdabiya Trough which totally encased in shales.
7. In the eastern flank of the Sirt Trough, the Paleocene is mainly increasing in thickness toward the
ramp margin.
8. Lower and Middle Eocene sediments (Ypresian - Lutetian) are existing throughout the Sirt Basin
and in the offshore Gulf of Sirt which represented by Gir and Gialo Formation.
9. Geological and geophysical data show the presence of channels with apparent calci-clastic
turbidities at the foot of the slope.
10. The formation thickens dramatically into the Ajdabiya Trough where there is impressive seismic
evidence of slumping, debris flows and turbidities from the ramp margin, down slope and into
deep-water.
11. Different types of Paleocene and Early Eocene Carbonate facies have peripheral distribution
around the Paleogene paleo-shorelines.
12. Nummulitic section of Middle Eocene (Lutetian) Gialo Formation in Sirt Basin is
sedimentologically very similar to the Jdeir Formation in the offshore Sabratah Basin.
13. This nummilitic belt follows the same general configuration and extends from the offshore
Sabratah Basin to the Jahamah Platform, swings around the still subsiding Ajdabiya Trough and
appears again at Gialo area.
14. The seismic data also shows the presence of channels in nummilitic section with apparent calciclastic turbidities at the foot of the slope.
15. Many of sigmoidal seismic features of Paleocene/Eocene stratigraphic clinoforms have been
interpreted in the seismic sections in eastern Ajdabiya areas controlled by the sea level
fluctuation during Middle Eocene time.
16. The extension of different nummulitic facies and their associated sediments of ramp platform
type along the Eastern Ajdabiya Trough and offshore area represent very important region for
hydrocarbon exploration.