Evaporites reveal Pleistocene basin dynamics in the Danakil depression (northern Afar, Ethiopia)

2020 ◽  
Author(s):  
Valentin Rime ◽  
Anneleen Foubert ◽  
Robin Fentimen ◽  
Haileyesus Negga ◽  
Afifé El Korh ◽  
...  
Keyword(s):  
Sea Level ◽  
Red Sea ◽  
Tectonic Activity ◽  
Carbonate Sediments ◽  
Accommodation Space ◽  
Salt Pans ◽  
Red Sea Rift ◽  
Ethiopian Plateau ◽  
Basin Subsidence ◽  
History Of

<p>The Danakil depression (Afar, Ethiopia) is a rift valley forming the southernmost part of the Red Sea rift. It is situated between the Ethiopian plateau and the Danakil block and is thought to represent an advanced stage of rifting, characterized by important tectonic and volcanic activity. Its floor is situated 120 meters below sea level and is covered by salt pans.</p><p>This study focuses on a 625 m deep borehole drilled in the central part of the basin. It mainly consists of evaporites dominated by halite along with clastic and carbonate sediments. Lithostratigraphy and facies description were completed by micropaleontological, geochemical, mineralogical and organic matter analysis. They reveal the complex history of this rift basin. Two marine Red Sea incursions are identified. Strong water stratification during the older marine incursion led to the formation of sapropel layers and magnesite. The restriction of the basin and the strong aridity led to the formation of evaporites, culminating in the deposition of potash salts. Between the two marine events, continental evaporites contributed to several hundreds of meters of basin fill.  The younger marine incursion was probably characterized by wetter environments, resulting in the deposition of smaller volumes of evaporites. Since then, hypersaline lakes and salt pans filled the basin. Ongoing radiocarbon and U/Th datings will constrain further the Pleistocene stratigraphy and timing of the marine incursions.</p><p>These findings shed a new light on the basin history. The successive flooding and desiccation events are a consequence of sea-level variations but also important tectonic activity. Rift margin uplift prevented flooding during the Holocene sea-level highstand and contributed to the restriction of the depression. Significant basin subsidence at very short time scales created accommodation space for the voluminous sediment infill. This implies very active rifting during the last 250 ka.</p>

Tectonic controls on the sedimentation patterns in the Danakil Depression, Afar, Ethiopia

2021 ◽  
Author(s):  
Valentin Rime ◽  
Anneleen Foubert ◽  
Léa Perrochet ◽  
David Jaramillo-Vogel ◽  
Haileyesus Negga ◽  
...  
Keyword(s):  
Sea Level ◽  
Red Sea ◽  
Passive Margin ◽  
Time Intervals ◽  
Western Margin ◽  
Accommodation Space ◽  
Volcanic Processes ◽  
Active Transition ◽  
Short Time ◽  
Mis 5E

<p>The Danakil depression in the northern part of the Afar is the only modern example of a rift undergoing the active transition from continental to marine settings, a crucial stage in rift and passive margin development. Thick evaporite deposits in its central part, and fringing Pleistocene coralgal reef terraces along its margins evidence at least four Red Sea incursions in to the basin and subsequent desiccation. The two youngest coralgal reef terraces were dated as respectively MIS 5e and MIS 7. Recent field expeditions measuring the paleo-shorelines' elevation provide a precious record of neotectonic activity in the basin. The margins show varied uplift while outcrops situated closer to the rift axis subsided below sea level. MIS 7 sediments at the northern, western margin, were uplifted up to 170 masl. Neotectonic movements are smaller on the eastern margin of the Danakil depression but moderate uplift was sufficient to avoid flooding of the depression during the Holocene. Syn-rift sedimentary patterns in the Danakil basin illustrate that the transition from continental to marine conditions is not gradual but marked by alternating marine and continental episodes. This alternation is controlled by the interaction between eustatic, tectonic and volcanic processes. Significant increase in accommodation space and sediment deposition can happen at very short time intervals.</p>

Biostratigraphically constrained Neogene palaeoenvironments of the Red Sea rift

2021 ◽  
Author(s):  
Geraint Hughes ◽  
Osman Varol
Keyword(s):  
Sea Level ◽  
Red Sea ◽  
Debris Flows ◽  
Middle Miocene ◽  
Depositional Environments ◽  
Early Miocene ◽  
Arabian Plate ◽  
Tectonic Activity ◽  
Gulf Of Suez ◽  
Gulf Of Aden

<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>

X V III. Discussion

1965 ◽  
Vol 258 (1088) ◽  
pp. 205-213 ◽  
Keyword(s):  
Red Sea ◽  
Continental Drift ◽  
Rift System ◽  
Gulf Of Aden ◽  
Vertical Movements ◽  
Red Sea Rift ◽  
Geological Features ◽  
Carlsberg Ridge ◽  
History Of ◽  
African Rift

We have heard many excellent arguments in favour of continental drift, based on the most recent results of studies of the ocean floors, the fit of the continents, the palaeomagnetic picture, and several instances of the relation between geological features and the supposed movement of the continents. It has struck me that these geological features are very restricted in number; they are either the oceanic rifts or wrench faults. Let us have a look first at the oceanic rifts. They are directly connected, through the Carlsberg Ridge and the Gulf of Aden with the Red Sea Rift and then through the Ethiopian faults with the famous African rifts. The history of the African rift system is relatively well known, and we know for certain that they represent principally vertical movements of the Earth’s crust, which have lasted at least from the Tertiary and probably since the Jurassic.

Tectonic History of Hoop Fault Complex, Barents Sea/Norway

2020 ◽  
Author(s):  
Volker Schuller ◽  
István Dunkl ◽  
Zsolt Schleder ◽  
Eirik Stueland
Keyword(s):  
Barents Sea ◽  
Early Stage ◽  
Upper Jurassic ◽  
Late Triassic ◽  
Tectonic Activity ◽  
Burial Depth ◽  
Seismic Section ◽  
Accommodation Space ◽  
Tectonic History ◽  
History Of

<p>The Barents Sea consists of several tectonic elements which were formed at different plate tectonic collisional and rifting stages. This work focuses on the Early Mesozoic to recent events of the central Barents Sea, the eastern edge of the Bjarmaland platform.</p><p>We have analysed the clastic deposits of Mid-Triassic to Upper Jurassic to reconstruct the tectonic history of the Hoop Fault Complex, Barents Sea/Norway. Apatite fission track and (U-Th)/He thermochronology were used to determine the maximum burial depths and exhumation history. According to the combined evaluation of results from shale ductility analysis (BIB-SEM), fault kinematic analysis and structural modelling (section balancing based on a 125 km long 2D seismic section line) the following tectonic evolution can be drawn: deflation of late Palaeozoic salt deposits was initiated by the tectonic activity on the early structures of the Hoop Fault zone. The orthogonal faults of the Hoop Fault Complex developed at the early stage, during Late Triassic to Early Jurassic times at relatively shallow depth, below 1000m. Ongoing subsidence related to the extension caused by the opening of the Atlantic Ocean created accommodation space for Upper Jurassic to Cenozoic deposits with maximum burial depth of 2000 m for the analysed Mid-Jurassic rocks. The exhumation of the Hoop Fault complex started around 10 Ma and remained constant until Quaternary times (140 m/Myr).</p>

scholarly journals Miocene Kareem Sequence, Gulf of Suez, Egypt

GeoArabia ◽  
2010 ◽  
Vol 15 (2) ◽  
pp. 175-204 ◽  
Author(s):  
Moujahed I. Al-Husseini ◽  
M. Dia Mahmoud ◽  
Robley K. Matthews
Keyword(s):  
Sea Level ◽  
Red Sea ◽  
Arabian Plate ◽  
Gulf Of Suez ◽  
Rift Basins ◽  
Third Order ◽  
Depositional Sequence ◽  
Marine Deposits ◽  
Red Sea Rift ◽  
Global Sea Level

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.

A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - Tectonic significance of regional geology and evaporite lithfacies in northeastern ethiopia

1970 ◽  
Vol 267 (1181) ◽  
pp. 313-329 ◽  
Keyword(s):  
Red Sea ◽  
Tectonic Activity ◽  
Ethiopian Rift ◽  
Gulf Of Aden ◽  
Submarine Canyons ◽  
Ethiopian Plateau ◽  
Continental Shelves ◽  
Tectonic Significance ◽  
The Alps ◽  
Eastern Edge

Mesozoic and Precambrian rocks are exposed in the Danakil Alps of coastal Eritrea, but the Danakil Depression between the Alps and the Ethiopian plateau is covered by Tertiary-Quaternary rocks. The physiography, structural geology, regional stratigraphy and evaporite lithof acies distribution of this area all suggest that it is underlain by an asymmetrically subsided block of old sialic crust. The western edge of this block has subsided deeply along the Ethiopian rift and is covered, in the Danakil Depression, by an evaporite-basalt veneer, but its eastern edge has been uplifted as the Danakil Alps. These are bounded on the east by a rift escarpment facing the Red Sea. Although geologic data here is sparse compared to the Danakil region, certain features suggest that a similar asymmetrically subsided block of older sialic rocks, with an evaporite-basalt veneer, may also lie beneath much of the Red Sea. This tectonic evolution apparently commenced in Miocene time with rifting near the centre of an earlier Mesozoic-Paleogene sedimentary basin. Uplift along this central rift caused tensional failure along a secondarily induced rift to the west, and east-side-down subsidence along this structure formed the asymmetrically subsided block. There were apparently two successive cycles of this tectonic activity. The earlier, of Miocene age, formed the easterly (Red Sea) block with a thicker veneer of older evaporitebasalt, and the later, of Plio-Pleistocene age formed the westerly (Danakil) block with a thinner veneer of younger evaporite-basalt. The separation of Arabia from Ethiopia across the southern Red Sea would thus be relatively minor, presumably represented by the width of the Red Sea’s axial trough plus a few kilometres across each of the Danakil Alp and Ethiopian rifts. Similar tectonic developments may accompany initial rifting and separation in the development of ocean basins by seafloor spreading, and might explain why oceans like the Atlantic, that have apparently developed in this manner, are fringed by shallow continental shelves with thick evaporite sequences and steep walled submarine canyons.

Sea-level and reef accretion history of Marine Oxygen Isotope Stage 7 and late Stage 5 based on age and facies of submerged late Pleistocene reefs, Oahu, Hawaii

2014 ◽  
Vol 81 (1) ◽  
pp. 138-150 ◽  
Author(s):  
Clark E. Sherman ◽  
Charles H. Fletcher ◽  
Ken H. Rubin ◽  
Kathleen R. Simmons ◽  
Walter H. Adey
Keyword(s):  
Oxygen Isotope ◽  
Sea Level ◽  
Late Stage ◽  
Sea Levels ◽  
Reef Accretion ◽  
Oxygen Isotope Stage ◽  
Accommodation Space ◽  
History Of ◽  
Mis 5

AbstractIn situ Pleistocene reefs form a gently sloping nearshore terrace around the island of Oahu. TIMS Th–U ages of in situ corals indicate that most of the terrace is composed of reefal limestones correlating to Marine Oxygen Isotope Stage 7 (MIS 7, ~ 190–245 ka). The position of the in situ MIS 7 reef complex indicates that it formed during periods when local sea level was ~ 9 to 20 m below present sea level. Its extensiveness and geomorphic prominence as well as a paucity of emergent in situ MIS 7 reef-framework deposits on Oahu suggest that much of MIS 7 was characterized by regional sea levels below present. Later accretion along the seaward front of the terrace occurred during the latter part of MIS 5 (i.e., MIS 5a–5d, ~ 76–113 ka). The position of the late MIS 5 reefal limestones is consistent with formation during a period when local sea level was below present. The extensiveness of the submerged Pleistocene reefs around Oahu compared to the relative dearth of Holocene accretion is due to the fact that Pleistocene reefs had both more time and more accommodation space available for accretion than their Holocene counterparts.

Structural evolution history of the Red Sea Rift

Geotectonics ◽  
2010 ◽  
Vol 44 (3) ◽  
pp. 271-282 ◽  
Author(s):  
G. A. F. d’Almeida
Keyword(s):  
Red Sea ◽  
Structural Evolution ◽  
Red Sea Rift ◽  
History Of

Phanerozoic Oxygen

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Oxygen Consumption ◽  
Organic Carbon ◽  
Sea Level ◽  
Time Scale ◽  
Atmospheric Oxygen ◽  
Sea Level Change ◽  
Oxygen Production ◽  
Level Change ◽  
History Of ◽  
Geologic Processes

This chapter discusses the modeling of the history of atmospheric oxygen. The most recently deposited sediments will also be the most prone to weathering through processes like sea-level change or uplift of the land. Thus, through rapid recycling, high rates of oxygen production through the burial of organic-rich sediments will quickly lead to high rates of oxygen consumption through the exposure of these organic-rich sediments to weathering. From a modeling perspective, rapid recycling helps to dampen oxygen changes. This is important because the fluxes of oxygen through the atmosphere during organic carbon and pyrite burial, and by weathering, are huge compared to the relatively small amounts of oxygen in the atmosphere. Thus, all of the oxygen in the present atmosphere is cycled through geologic processes of oxygen liberation (organic carbon and pyrite burial) and consumption (weathering) on a time scale of about 2 to 3 million years.

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