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Paleozoic Sequences, Stratigraphic Correlation, and Hydrocarbon Potential in Iraq and Adjacent Countries, North Arabian Peninsula


Hassan, Aboosh H., Iraq North Oil Co, Kirkuk, Iraq


The Paleozoic sequences in Iraq represent mega-sequences separated by major uncon­formity surfaces (sequence boundaries). These sequences have been penetrated in north and west Iraq and consist of, from older to younger: Tippecanoe Sequences (Ordovician – Silurian): Khabour Fm. (Lower & Middle Ordovician) & Akkas Fm. (Silurian). Important hydrocarbon Reservoir, Source, and Seal rocks include the Kaskaskia Sequences (Middle DevoniamLower Carboniferious) Pirispiki, Kaista, Ora & Harur fms. Hydrocarbon reser­voir rocks include Absaroka Sequences (Carboniferious – Permian) Ga’ara Fm. (Permo-Carboniferious and Permian) & Chizaziri Fm. (Upper Permian ”Thuringian”).

The correlation of these major sequences with adjacent countries shows that the Upper Paleozoic section is missing in eastern Jordan (Risha basin) and the Devonian system is missing in eastern Syria. Conversely, all Paleozoic sequences that are recorded in Saudi Arabia (Widyan basin) are correlative with southern and southwestern Iraq.

The majority of these stratigraphic differences are attributed to tectonic pulses during Caledonian and Hercynian episodes affecting the architecture of these sedimentary basins in the Paleozoic Era. The areal distribution of these components of the Paleozoic sequence has important implications for the hydrocarbon system of western Iraq and adjacent areas.