Petroleum stratigraphy of the northeast Africa Middle East region

Abstract

Carbonate-clastic-evaporite sediments of Infra-Cambrian through Holocene age were cyclically deposited in a relatively continuous belt around the eastern and northern borders of the Nubian-Arabian craton, mainly on a broad shallow-water platform adjacent to the proto-Tethys and Tethys seaway. All or part of the Paleozoic section is absent by non-deposition or erosion over much of the region but reaches a substantial thickness in the subsurface of the Middle East and in northern Africa adjacent to the Mediterranean Sea. Post-Paleozoic deposition was more or less continuous across the entire craton border region in the Middle East and along the northern border of the Sahara platform in North Africa and in Somalia-eastern Ethiopia. Total thickness of preserved sedimentary cover across this vast shallow-water marine platform and bordering oceanic realm is 6,500 to at least 33,000 ft (2 to 10 km) in and adjacent to the Arabian-Iranian basin, 6,500 to 30,000 ft (2 to 9 km) in and adjacent to northern Egypt, Libya, and Tunisia, and 3,500 to 20,000 ft (1 to 6 km) in the Horn of Africa (Somalia). To varying degrees, similar marine and associated sedimentary rock facies are present in all of these regions, although paleotectonic-stratigraphic interrelationships and continental positions during drift have greatly affected petroleum generation and accumulation in the several regions of the craton border. A series of regional stratigraphic-sedimentary environment and continental-position layer maps attempts to show the relative influence of these factors through geologic time with respect to the relationships between petroleum reservoirs, source rocks, and confining rock facies. Data and information used in preparing this report were compiled from many sources, including a wealth of published papers and information from numerous professional geological journals, articles from The Oil and Gas Journal and World Oil, and the information files of Petroconsultants S.A. Important selected references are listed in the bibliography, although numerous useful published papers on specific oil or gas fields and local studies are not necessarily included. The work on North Africa and the Middle East was completed as part of the ongoing World Energy Resources Program of the U.S. Geological Survey.

The crustal and upper-mantle structure of the interior Arabian platform

“…(1998). This depth is also in good agreement with the depth to basement found from oil exploration wells in the Riyadh region (Peterson & Wilson 1986), which also found the basement to be at 3 km.…”

Petroleum systems in the Middle East

“…Several strike-slip faults of regional significance occur in the Zagros Fold Belt. These commonly appear to follow pre-existing Mesozoic faults which acted during the compressive phases boundaries between the differentially folded segments, resulting from the closure of the southern Tethys during Late Cretaceous -Early Tertiary time and from further compression as the Afro -Arabian Plate collided with the central Iranian Plate during the Miocene-Pliocene (Henson 1951;Peterson & Wilson 1986). …”

“…Approximate thickness of Phanerozoic sedimentary rocks in the Middle East (modified fromPeterson & Wilson 1986;Alsharhan & Nairn 1997).…”

“…SW-NE structural-stratigraphic cross-section from Arabian Shield to High Zagros Mountains across the Arabian Shelf, Arabian Gulf and Zagros Fold Belt (modified fromPeterson & Wilson 1986). …”

A revised budget for Cenozoic sedimentary carbon subduction

“…In this case two drill sites on either side of the fore-arc ridge are employed: one on the Herodotus Abyssal Plain (DSDP Site 131) and the other to the west on the Messina Abyssal Plain (DSDP Site 364). The carbon contents of these deep-water sediments are presumed to represent the whole stratigraphy, although the uncertainties in this case are much higher than in other margins considered because the sediment is too thick to be sampled by drilling and the lithologies cannot be known with any confidence, beyond a general understanding that there is no reason that it would not be typical of mixed clastic-carbonate rifted margin stratigraphies, as broadly confirmed by petroleum drilling offshore and linked outcrop studies [Mriheel, 2015;Peterson and Wilson, 1987]. Onshore studies of the Gabes-Tripoli Basin indicate the presence of some organic-rich sedimentary rocks in Middle Triassic, middle Cretaceous and the lower Eocene strata, interbedded with a dominant organic carbon-poor mixed clastic-carbonate sequence [Mriheel, 2015].…”