Paleozoic tectono-stratigraphic framework of the Arabian Peninsula

Thick Paleozoic succession of siliciclastics and carbonates is well exposed and penetrated in the greater Arabian Basin. The succession included source, reservoir, and seal rocks. Though, oil and gas have been discovered in sandstone and limestone reservoirs in these rocks in several oilfields in the basin, the tectonic history of this succession has not been fully understood yet. The Paleozoic succession of the basin is severely affected by series of major climatic and tectonic events which have caused facies change and major stratigraphic breaks. The major tectonic movements have resulted in dividing the Paleozoic succession into mega-depositional cycles. The succession is subdivided into pre- and syn-climatic and tectonic events representing well defined depositional cycles separated by regional unconformities. These mega-depositional cycles are well preserved in basinal or less tectonically affected areas where boundaries between the respective cycles are marked by possible hiatus. In more tectonically active areas, the Paleozoic succession is less preserved and boundaries between the cycles are more complicated due to longer periods of erosion by later movements and/or non-deposition. Minor stratigraphic breaks within the mega cycles subdivide them into smaller sub-cycles. Following the deposition of the Late Caradocian Quwarah member of the Qasim Formation the area went through a gentle uplift and tilt probably related to the Taconic tectonic movements, and a drop of sea level due to glaciation. Thick succession of the Quwarah, Ra’an, Kahfah, and Hanadir members of the Qasim Formation and the Risha and Sajir members of the Saq Formation were eroded and deep paleo-valleys incised in outcrops of the two formations. Glacial and periglacial deposits of the Zarqa and/or Sarah Formations were unconformably rest on older units from Ordovician to Precambrian.