Lithostratigraphy of the Red Sea Region

GeoArabia, Vol. 10, No. 3, 2005 Gulf PetroLink, Bahrain Lithostratigraphy of the Red Sea Region Geraint Wyn ap Gwilym Hughes and Robert S. Johnson ABSTRACT The onshore and offshore Saudi Arabian Red Sea region contains a series of lithostratigraphic units that have not previously been formally defined and described. Based on an intensive study of the succession, a lithostratigraphic scheme is proposed in a lexicon format that integrates biostratigraphic, sedimentological, seismic and field studies from the Midyan Peninsula in the north, to the Jizan Coastal Plain in the south. In view of the economic aspect of the Neogene succession and greater accessibility to Neogene subsurface samples, emphasis has been placed on a revision of the Neogene lithostratigraphy. Resting upon Proterozoic Basement, the sedimentary succession was deposited during the Cretaceous to Pleistocene times. The oldest pre-ri� Suqah Group nonconformably overlies the Proterozoic Basement and consists of Upper Cretaceous shales of the Adaffa Formation and Cretaceous to Palaeogene sandstones, shales and thin limestones of the Usfan Formation. A series of volcanics includes the early to middle Oligocene Matiyah Formation and the late Oligocene-early Miocene Jizan Group. The Neogene succession displays a great lithological diversity. The Tayran Group (Al Wajh, Musayr and Yanbu Formations) includes marginal marine siliciclastics of the Al Wajh Formation, and represents the earliest ri�-associated sediments deposited during the earliest Miocene. These are conformably overlain by lower Miocene shallow- marine carbonates of the Musayr Formation. In some of the central Red Sea onshore basins, thick lower Miocene submarine evaporites of the Yanbu Formation were deposited under locally restricted conditions and form the third formation of the Tayran Group. Rapid subsidence during the early Miocene caused deposition of deep-marine, planktonic-foraminiferal mudstones and thick submarine fan sandstones of the Burqan Formation. Carbonates, marine mudstones and submarine evaporites of the Maqna Group (Jabal Kibrit and Kial Formations) unconformably overlie the Burqan Formation and were deposited during latest early Miocene to earliest middle Miocene. The Jabal Kibrit Formation consists of an anhydrite-carbonate facies, of which the carbonates form the Wadi Waqb Member. Siliciclastic facies of the Jabal Kibrit Formation are termed the Umm Luj Member. Above the Jabal Kibrit Formation, the Kial Formation is typified by interbedded anhydrites, calcareous siltstones and carbonates, and includes the Sidr, Nakhlah, Yuba, Rayaman and Sabya Members. Within the region, thick evaporites of the Mansiyah Formation were deposited extensively during the middle Miocene, and are overlain by poorly exposed sands, shales and thin anhydrite beds of the middle to upper Miocene Ghawwas Formation. The Lisan Group unconformably overlies the Ghawwas Formation and consists of coarse alluvial sands and gravels of possible Pliocene to Holocene age. INTRODUCTION Between 1967 and 1976, ten deep exploratory wells were drilled in the Saudi Arabian Red Sea by international oil companies, and between 1982 and 1986 six shallow stratigraphic wells were drilled in the Yanbu coastal region (Figure 1). The sedimentary successions penetrated by these wells were readily equated with the standard lithostratigraphy of the well-explored Gulf of Suez in Egypt, but no systematic a�empt was made, at that time, to establish a formal stratigraphic succession. Between 1990 and 1994 (Figure 1), Saudi Aramco undertook an intensive exploration program in the Red Sea and drilled 14 exploratory wells (1992–1994); an additional four wells were drilled in 1998. During the Saudi Aramco exploration program, detailed field observations were made in the Midyan (Figure 1a), Al Wajh (Figure 1b), Yanbu (Figure 1c), Jiddah (Figure 1d), Ghawwas (Figure 1e), and Jizan (Figure 1f) coastal areas. Fieldwork was focused on the Midyan coastal area where the most complete 49 Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/10/3/49/4564937/hughes.pdf by guest on 25 September 2021 Hughes and Johnson Red Sea Lithostratigraphy, Saudi Arabia � �� 50 51 Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/10/3/49/4564937/hughes.pdf by guest on 25 September 2021 Hughes and Johnson Red Sea Lithostratigraphy, Saudi Arabia � �� Figure 1: Landsat image of the Red Sea, �� showing locations of sub-basins: �� (a) Midyan Basin, northern Red Sea; �� (b) Al Wajh Basin, north-central Red Sea; �� (c) Yanbu Basin, central Red Sea; �� (d) Jiddah Basin, central Red Sea; (e) Ghawwas Basin, south-central Red Sea and �� (f) Jizan Basin, southern Red Sea. �� 50 51 Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/10/3/49/4564937/hughes.pdf by guest on 25 September 2021 Hughes and Johnson Red Sea Lithostratigraphy, Saudi Arabia �� Figure 2: Correlation diagram of the Phanerozoic formations of the Red Sea region (modified from Beydoun (1991), and Hughes and Beydoun (1992)). Note lithology in following figures are colored as indicated. range of lithostratigraphic units is extensively exposed and easily accessed. Supplementary fieldwork in the Midyan region was carried out in 1997 by Saudi Aramco and the King Fahd University of Petroleum and Minerals Research Institute (KFUPM-RI) to investigate the stratigraphy of additional exposures of the Wadi Waqb Reservoir equivalent carbonates (1998, KFUPM Report). This project also provided a new geological map and structural synthesis for the Midyan region, incorporating satellite images derived from the Landsat Thematic Mapper (TM). A new technique for imaging the pre-Mansiyah fault blocks in the Midyan region was discussed by Mougenot and Al-Shakhis (1999). The results of the Saudi Aramco work have been documented as Saudi Aramco unpublished reports (A.M. Afifi, T.C. Connally, M. Senalp and G.W. Hughes, 1993; G.S. Ferguson, 1993a, b; G.S. Ferguson and M. Senalp, 1993; G.S. Ferguson, M. Senalp and A.M. Afifi, 1993; G.W. Hughes and R.A. Kamal, 1993a, b, c; R.A. Kamal and G.W. Hughes, 1993 a, b; R.S. Johnson, D. Rodgers and G.R. Savage, 1995) and published by Hughes and Filatoff (1995), Kamal and Hughes (1995), Filatoff and Hughes (1996), and Hughes et al. (1998a, b; 1999). 52 53 Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/10/3/49/4564937/hughes.pdf by guest on 25 September 2021 Hughes and Johnson Red Sea Lithostratigraphy, Saudi Arabia TABLE 1 WELLS AND LOCALITIES CITED IN STUDY Well Abbreviation Longitude Latitude Figure Ad Dubaybah 28°27’09.9”N 35°05’19.8”E 77, 80, 81 Al Khuraybah 28°04’50.2”N 35°11’36”E 72 Al Wajh South-1 AWSO-1 25°14’23.8”N 37°12’28.6”E 29, 58, 88 An Numan-1 ANMN-1 27°04’43”N 35°46’31”E 70 Aynunah Graben 28°05’45”N 35°16’03.4”E Badr-1 BADR-1 23°35’52.3”N 38°26’22.7”E 102 Burqan-3 BRQN-3 34°04’04”N 27°55’47”E 51, 89 Dhaylan-1 DYLN-1 25°30’37.2”N 37°02’54.6”E

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