Tectono-Stratigraphic Comparison of Two Petroliferous Provinces in the Northeastern Iraqi Portion of the Arabian Plate

Richard P. George¹*, Tayfoor Rushdi², and George J. Grabowski^3
1ExxonMobil Exploration Co., USA
²Iraq Oil Exploration Company
³ExxonMobil, USA
*[email protected]

Northeastern Iraq has two contiguous, petroliferous tectono-stratigraphic provinces that lie at similar regional structural elevations and yet have contrasting play elements, owing to their different Late Mesozoic to Cenozoic evolution: (1) Kirkuk embayment foldbelt (“Kirkuk”, from the Hamrin Mountains northeastward in the Kurdistan part of Iraq), with Tertiary reservoirs in high-relief anticlines; and (2) northwestern Mesopotamian foreland (“NW Mesopotamia”, the northern Mesopotamian Plains, from the Hamrin Mountains southwestward to the Euphrates River), with Cretaceous reservoirs in low-relief traps. Both provinces were within the Gotnia Basin during the Late Jurassic and in similar carbonate-prone depositional environments until the Late Cretaceous. Late Cretaceous obduction of Tethyan ophiolites onto northeastern Arabia created an orogenic load and sedimentary provenance that affected Kirkuk and NW Mesopotamia differently. Kirkuk was in a NW-trending foredeep, with clastic input on its northeast flank and deep-water, reservoir-poor carbonates on its southwest flank. NW Mesopotamia remained part of the Arabian platform with deposition of reservoir-prone carbonates. Tectono-stratigraphic differentiation between the obduction-related Kirkuk foreland basin and the NW Mesopotamian platform lingered through the Paleogene and Early Miocene. The Kirkuk foreland accumulated several hundred meters of Eocene to lower Lower Miocene carbonates that are its principal reservoirs. In contrast, NW Mesopotamia accumulated much thinner Paleogene to Lower Miocene carbonates. Collision of the Arabian and Eurasian plates in the Neogene created first the Taurides and then the Zagros Mountains. Kirkuk underwent northwestward-increasing truncation of Paleogene reservoirs beneath a pre-late Early Miocene unconformity, then rapid burial in the Zagros Foreland Basin, and finally uplift, as large anticlinal traps grew as far southwest as the Hamrin trend. Meanwhile, NW Mesopotamia subsided as part of the Zagros Foredeep.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain