Biostratigraphically constrained Neogene palaeoenvironments of the Red Sea rift

Author(s):  
Geraint Hughes ◽  
Osman Varol

<p>Marine sediments deposited in response to the Neogene opening of the Red Sea during divergence of the African-Arabian plate margin provide micropalaeontological chronological evidence to calibrate synchronous palaeoenvironmental events from the Gulf of Suez to the Gulf of Aden. This facility provides insights to the timing and relative rates of tectonic subsidence associated with the rifting episodes of the region. Biostratigraphic index forms include planktonic and benthonic foraminifera and calcareous nannofossils. These, combined with various associated microfossils and macrofossil fragments, permit interpretation of a range of depositional environments that span intertidal to bathyal regimes. Onset and recovery from various hypersaline events are similarly interpreted by integrating microfossils and lithology. Following an episode of emergence and sporadic volcanicity, subsidence and the first Neogene marine transgression created brackish to shallow marine lagoons during the Early Miocene (Foraminiferal Letter Stage Upper Te). Rapid subsidence and accumulation of deep marine mudstones, of local hydrocarbon source-rock quality, with thinly interbedded siliciclastic and calciclastic debris flows commenced in the Early Miocene (Planktonic foraminiferal zones N5-N8; Nannofossil zones NN3-NN5). The debris flows increased in abundance and provide good hydrocarbon reservoirs. The Gulf of Suez and Red Sea experienced episodic isolation from the Indian Ocean during the latest Early Miocene and earliest Middle Miocene (Planktonic foraminiferal zones N8-N9; Nannofossil zone NN5 Foraminiferal Letter Stage Middle-Upper Tf1), resulting in hypersaline events with precipitation of submarine gypsum and halite. The isolation is attributed to constriction of the southern Red Sea, in the vicinity of the Bab El Mandab Straits, by eustatic sea level fall as well as probable tectonic activity; the synchronous Gulf of Aden succession does not display evidence for such hypersaline events. A prolonged hypersaline phase extended over most of the Middle Miocene, for which absence of biostratigraphic data precludes age control. During the latest Middle Miocene to Late Miocene, rejuvenation of the hinterland cause rapid deposition of terrestrial and fluviatile coarse and fine siliciclastics, with similar biostratigraphic paucity except for rare diatoms and palynomorphs. Renewed subsidence, associated with opening of the Aqaba Fault, combined with eustatic sea level rise caused marine deposition to recommence in the Pliocene.</p>

2021 ◽  
Vol 11 (6) ◽  
pp. 2497-2518
Author(s):  
Syed Haroon Ali ◽  
Osman M. Abdullatif ◽  
Lamidi O. Babalola ◽  
Fawwaz M. Alkhaldi ◽  
Yasir Bashir ◽  
...  

AbstractThis paper presents the facies and depositional environment of the early Miocene Dam Formation, Eastern Arabian platform, Saudi Arabia. Deposition of Dam Formation (Fm.) was considered as a restricted shallow marine deposition. Few studies suggest the role of sea-level change in its deposition but were without decisive substantiation. Here, we describe the facies and high-resolution model of Dam Fm. under varying depositional conditions. The depositional conditions were subjected to changing relative sea level and tectonics. High-resolution outcrop photographs, sedimentological logs, and thin sections present that the mixed carbonate–siliciclastic sequence was affected by a regional tectonics. The lower part of Dam Fm. presents the development of carbonate ramp conditions that are represented by limestones and marl. The depositional conditions fluctuated with the fall of sea level, and uplift in the region pushed the siliciclastic down-dip and covered the whole platform. The subsequent rise in sea level was not as pronounced and thus allowed the deposition of microbial laminites and stromatolitic facies. The southeast outcrops, down-dip, are more carbonate prone as compared to the northwest outcrop, which allowed the deposition of siliciclastic-prone sedimentation up-dip. All facies, architecture, heterogeneity, and deposition were controlled by tectonic events including uplift, subsidence, tilting, and syn-sedimentary faulting, consequently affecting relative sea level. The resulting conceptual outcrop model would help to improve our understanding of mixed carbonate–siliciclastic systems and serve as an analogue for other stratigraphic units in the Arabian plate and region. Our results show that Dam Fm. can be a good target for exploration in the Northern Arabian Gulf.


GeoArabia ◽  
2014 ◽  
Vol 19 (4) ◽  
pp. 59-108
Author(s):  
G. Wyn Hughes

ABSTRACT The Saudi Arabian Red Sea stratigraphy consists of a variety of lithologies that range from evaporites, deep- and shallow-marine siliciclastics and carbonates, biostratigraphically constrained to range from the Late Cretaceous, Campanian, to Late Pliocene. The succession consists of pre-rift Mesozoic and Palaeogene sediments, and syn-rift and post-rift late Palaeogene and Neogene sediments. Three main episodes of shallow-marine carbonate deposition can be determined, including those of the earliest Early Miocene Musayr Formation of the Tayran Group later Early Miocene Wadi Waqb Member of the Jabal Kibrit Formation and of the Pliocene Badr Formation of the Lisan Group. The Midyan area of the northern Red Sea offers a unique window into the Cretaceous and Miocene succession that is otherwise only present in the deep subsurface. The sediments are of hydrocarbon interest because of the presence of source rocks, siliciclastic and carbonate reservoirs. The Wadi Waqb reservoir is hosted within the Wadi Waqb Member of the Jabal Kibrit Formation, and is of latest Early Miocene to possibly earliest Middle Miocene age. It is considered to have formed a fringing reef complex that formed a steep, fault-influenced margin to a narrow platform, similar to Recent coralgal reefs of the Red Sea. The Wadi Waqb Member is exposed on the east and west flanks of the Ifal Plain. The bioclasts are considered to have traveled as a submarine carbonate debris flow 25 km from their presumed source to the east and possibly the west, and consist mostly of rhodoliths, echinoid and coral fragments together with the benthonic larger foraminifera Operculinella venosa, Operculina complanata, Heterostegina depressa and Borelis melo. The planktonic foraminifera include species of Globigerina, Globigerinoides and Praeorbulina; no specimens of the Middle Miocene planktonic foraminiferal genus Orbulina have yet been encountered in the thin sections. The presence of Borelis melo melo, and of B. melo curdica within the region, indicates a latest Early Miocene age. No specimens of the age-equivalent larger benthonic foraminiferal genera Miogypsina or Lepidocyclina have been observed, and this is consistent with evidence from the Wadi Waqb equivalent carbonates elsewhere in the Red Sea and Gulf of Suez. In the east, the Wadi Waqb is represented by discontinuous fringing rhodolith and coral reefs that are welded to steep cliffs of granitic basement. In Wadi Waqb, located in hills that form the western margin to the Ifal Plain, the Wadi Waqb carbonates consist of packstones containing autochthonous planktonic foraminifera and abundant shallow-marine microfossils that are considered to have been derived from the basement-founded rhodolith and coral reefs in the east. The Wadi Waqb reservoir is located beneath the central part of the Ifal Plain, approximately midway down a ramp between the in situ rhodolith-coral reefs and the mixed allochthonous and autochthonous facies at Wadi Waqb. The reservoir contains biofacies similar to those exposed in Wadi Waqb, and indicative of a deep-marine environment, in excess of 50 m water depth. The Wadi Waqb carbonates display sedimentological and petrographic features that closely resemble those described from stratigraphically equivalent carbonates from the localities along the west coast of the Gulf of Suez, including Abu Shaar, where three depositional facies have been defined. It is apparent that these shallow-marine carbonates were established along the west and east rift margins of the Red Sea-Gulf of Suez rift complex prior to their dislocation during the Late Miocene and Pliocene by the left-lateral Aqaba faulting.


GeoArabia ◽  
2010 ◽  
Vol 15 (2) ◽  
pp. 175-204 ◽  
Author(s):  
Moujahed I. Al-Husseini ◽  
M. Dia Mahmoud ◽  
Robley K. Matthews

ABSTRACT The Miocene Kareem Formation in the Egyptian Gulf of Suez, and its equivalent formations throughout the Red Sea (250–550 m thick), contain one of the most important petroleum reservoirs in these highly faulted rift basins. They present a difficult exploration target, particularly over the shelves of the sparsely explored Red Sea for several reasons: (1) water depth exceeds one kilometer, (2) they underlie thick evaporites (including salt exceeding one kilometer in thickness), (3) they are difficult to image by conventional seismic techniques, and (4) their lithology is laterally variable and difficult to predict (anhydrite, carbonate, sandstone, shale and marl). The target Red Sea formations are best controlled by boreholes in the Gulf of Suez, where the Kareem Formation and its members are characterized by various synonymous units. A review of representative data and interpretations shows that the formation and its members are better understood when considered as a third-order, transgressive-regressive (T-R) depositional sequence, named the Kareem Sequence in the Middle East Geologic Time Scale (ME GTS). The Sequence is bounded above by the Belayim Sequence Boundary (Sub-Belayim Unconformity) and below by the Kareem Sequence Boundary (Sub-Kareem Unconformity), both corresponding to major sea-level lowstands. It contains the Arabian Plate Langhian Maximum Flooding Surface Neogene 30 (MFS Ng30) at the top of the Kareem Maximum Flooding Interval (MFI). Its lower Rahmi Member forms the majority of the transgressive systems tract (TST). The Kareem MFI and regressive systems tract (RST or HST) occur within the upper Shagar Member. The paleontology of the Formation is characterized by Planktonic Foraminiferal Zone N9 and in recent papers also N8, and Calcareous Nannofossil Biozone NN5, but the Formation’s assignment to Miocene stages (Burdigalian, Langhian and Serravallian) is unresolved in the literature. In this paper, the Kareem Sequence is interpreted in terms of Kareem subsequences 1 to 6. At semi-regional scales (10s of km), the older three are each represented by an anhydrite bed (Rahmi Anhydrite 1 to 3, each c. 10 m thick) overlain by deep-marine deposits (shale, marl and carbonate, 10s of meters thick). Subsequences 4 to 6 are represented in El Morgan field (Kareem A to C units), and in representative boreholes, by three deep-marine shale/marl units, each of which is overlain by a regressive shallow-marine sandstone unit. The Kareem Sequence is correlated to third-order orbital sequence DS3 1.1 with a depositional period of ca. 2.43 million years between ca. 16.1 and 13.7 million years before present (Ma), or numerically the latest Burdigalian, Langhian and earliest Serravallian (Langhian: 15.97–13.65 Ma in GTS 2004; 15.97–13.82 Ma in GTS 2009). The six subsequences are correlated to the orbital 405,000 year eccentricity cycle (referred to as Stratons 40–35 or DS4 1.1.1 to 1.1.6). The older three subsequences form the transgressive systems tract; the fourth contains the maximum flooding interval MFI (ca. 14.9–14.7 Ma) in its lower part. The regressive systems tract starts in the upper part of the fourth subsequence and encompasses subsequences 5 and 6. The orbital architecture of the Sequence provides a simplified framework for predicting lithology and reservoir development. The six Kareem subsequences carry the orbital-forcing glacio-eustatic signal. During low eccentricity, Antarctic ice-making and global sea-level drops, the northernmost Gulf of Suez and Bab Al Mandeb Strait restricted marine circulation in the Gulf and Red Sea rift basins. The resulting evaporitic setting was associated with the deposition of the Rahmi Anhydrite 1 to 3 beds and exposure over paleohighs. The deeper-marine deposits above the three Rahmi Anhydrite beds, and those of subsequences 4 to 6 reflect high eccentricity, Antarctic ice-melting, global sea-level rises, pluvial conditions at low latitudes (10–30oN), and open-marine circulation in the Red Sea. During pluvial periods, fluvio-deltaic systems prevailed over the mountainous rift shoulders and coastal plains and carried massive clastics into the Gulf and Red Sea Basins.


2011 ◽  
Vol 7 (2) ◽  
pp. 1195-1233 ◽  
Author(s):  
G. Trommer ◽  
M. Siccha ◽  
E. J. Rohling ◽  
K. Grant ◽  
M. T. J. van der Meer ◽  
...  

Abstract. This study investigates the response of Red Sea circulation to sea level and insolation changes during termination II and across the last interglacial, in comparison with termination I and the Holocene. Sediment cores from the central and northern part of the Red Sea were investigated by micropaleontological and geochemical proxies. The recovery of the planktonic foraminiferal fauna following high salinities during MIS 6 took place at similar sea-level stand (~50 m below present day), and with a similar species succession, as during termination I. This indicates a consistent sensitivity of the basin oceanography and the plankton ecology to sea-level forcing. Based on planktonic foraminifera, we find that increased water exchange with the Gulf of Aden especially occurred during the sea-level highstand of interglacial MIS 5e. From MIS 6 to the peak of MIS 5e, northern Red Sea SST increased from 21 °C to 25 °C, with about 3 °C of this increase taking place during termination II. Changes in planktonic foraminiferal assemblages indicate that the development of the Red Sea oceanography during MIS 5 was strongly determined by insolation and monsoon strength. The SW Monsoon summer circulation mode was enhanced during the termination, causing low productivity in northern central Red Sea core KL9, marked by high abundance of G. sacculifer, which – as in the Holocene – followed summer insolation. Core KL11 records the northern tip of the intruding intermediate water layer from the Gulf of Aden and its planktonic foraminifera fauna shows evidence for elevated productivity during the sea-level highstand in the southern central Red Sea. By the time of MIS 5 sea-level regression, elevated organic biomarker BIT values suggest denudation of soil organic matter into the Red Sea and high abundances of G. glutinata, and high reconstructed chlorophyll-a values, indicate an intensified NE Monsoon winter circulation mode. Our results imply that the amplitude of insolation fluctuations, and the resulting monsoon strength, strongly influence the Red Sea oceanography during sea-level highstands by regulating the intensity of water exchange with the Gulf of Aden. These processes are responsible for the observation that MIS 5e/d is characterized by higher primary productivity than the Holocene.


Author(s):  
C.L.V. Monty ◽  
J.M. Rouchy ◽  
A. Maurin ◽  
M.C. Bernet-Rollande ◽  
J.P. Perthuisot
Keyword(s):  
Red Sea ◽  

H. M. E. Schürmann ( The Hague ). I would like to remark that epeirogenetic movements in the Precambrian of the Gulf of Suez and the northern Red Sea area have been proven. They are of Precambrian age as they have been observed underneath the Hammamat (youngest Precambrian) transgression. In Palaeozoic times several marine ingressions took place and similar ingressions occurred in Permian, Jurassic and Cretaceous times, indicating continued subsidence. The big clysmic taphrogeny took place in young Tertiary times.


2019 ◽  
Vol 11 (19) ◽  
pp. 2224 ◽  
Author(s):  
Kamal A. Alawad ◽  
Abdullah M. Al-Subhi ◽  
Mohammed A. Alsaafani ◽  
Turki M. Alraddadi ◽  
Monica Ionita ◽  
...  

Falling between seasonal cycle variability and the impact of local drivers, the sea level in the Red Sea and Gulf of Aden has been given less consideration, especially with large-scale modes. With multiple decades of satellite altimetry observations combined with good spatial resolution, the time has come for diagnosis of the impact of large-scale modes on the sea level in those important semi-enclosed basins. While the annual cycle of sea level appeared as a dominant cycle using spectral analysis, the semi-annual one was also found, although much weaker. The first empirical orthogonal function mode explained, on average, about 65% of the total variance throughout the seasons, while their principal components clearly captured the strong La Niña event (1999–2001) in all seasons. The sea level showed a strong positive relation with positive phase El Niño Southern Oscillation in all seasons and a strong negative relation with East Atlantic/West Russia during winter and spring over the study period (1993–2017). We show that the unusually stronger easterly winds that are displaced north of the equator generate an upwelling area near the Sumatra coast and they drive both warm surface and deep-water masses toward the West Indian Ocean and Arabian Sea, rising sea level over the Red Sea and Gulf of Aden. This process could explain the increase of sea level in the basin during the positive phase of El Niño Southern Oscillation events.


Tectonics ◽  
2010 ◽  
Vol 29 (3) ◽  
Author(s):  
Abdullah ArRajehi ◽  
Simon McClusky ◽  
Robert Reilinger ◽  
Mohamed Daoud ◽  
Abdulmutaleb Alchalbi ◽  
...  
Keyword(s):  
Red Sea ◽  

GeoArabia ◽  
2012 ◽  
Vol 17 (1) ◽  
pp. 17-44 ◽  
Author(s):  
Moujahed I. Al-Husseini

ABSTRACT Egypt’s Late Oligocene–Early Miocene Nukhul Formation was deposited during the earliest geological evolution of the Gulf of Suez and Red Sea Rift System. In this paper the formation is cast as a depositional sequence based on published sections, and correlated across the Gulf of Suez and northern Red Sea. The resulting correlations indicate that deposition was initiated in local grabens by the oldest continental clastics of the lower member of the Nukhul Formation, the Shoab Ali Member. The member overlies the Suez Rift Unconformity, a term proposed for the entire Red Sea. Although this member can attain a thickness of ca. 1,000 ft (305 m) locally in grabens, it is generally absent over horsts. Sedimentary facies of the member are interpreted as indicating an initial alluvial-fluvial setting that evolved to an estuarine and coastal setting. The upper part of the Nukhul Formation records a regional shallow-marine transgression, which can be subdivided into three correlative Upper Nukhul members. These sediments are absent over the highest paleo-horsts, but reach up to 900 ft (275 m) in thickness in grabens. In the southern Gulf of Suez the Ghara Member represents the Upper Nukhul members. In places it consists of four cycles, each of which starts with an anhydrite bed and is overlain by deposits of mixed lithology (sandstone, marl, and limestone). The four cycles are interpreted as transgressive-regressive subsequences that can be correlated across ca. 60 km in the Gulf of Suez. The Ghara Member correlates to Saudi Arabia’s Yanbu Formation, which consists of massive salt in wells drilled on the Red Sea coastal plains. The Yanbu Salt is dated by strontium-isotope analysis at ca. 23.1–21.6 Ma (earliest Aquitanian). The Nukhul Formation is capped by the Sub-Rudeis Unconformity or correlative Rudeis Sequence Boundary, and overlain by the Rudeis Formation. The Nukhul Formation is here proposed as the Nukhul Sequence and defined in the Wadi Dib-1 Well, wherein it consists of Nukhul subsequences 1 to 10 (in descending order, ranging in thickness between 33–84 m). The lower six Nukhul subsequences 10 to 5 are characterized by shale-to-sandstone cycles of the Shoab Ali Member, and the upper four are represented by the cycles of the Ghara Member. The 10 subsequences are interpreted as tracking the 405,000 year eccentricity signal of the Earth’s orbit and to span ca. 4.0 million years between ca. 25.0 and 21.0 Ma.


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