Fine-grained sediments of the Zaire deep-sea fan, southern Atlantic Ocean

1984 ◽  
Vol 15 (1) ◽  
pp. 95-113 ◽  
Author(s):  
T. C. E. van Weering ◽  
J. van Iperen
Keyword(s):  
Atlantic Ocean ◽  
Deep Sea ◽  
Fine Grained ◽  
Sea Fan ◽  
Southern Atlantic Ocean

scholarly journals The Ogooue Fan (offshore Gabon): a modern example of deep-sea fan on a complex slope profile

Solid Earth ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 851-869 ◽  
Author(s):  
Salomé Mignard ◽  
Thierry Mulder ◽  
Philippe Martinez ◽  
Thierry Garlan
Keyword(s):  
Deep Sea ◽  
Sedimentary Facies ◽  
Turbidity Currents ◽  
Slope Gradient ◽  
Seismic Reflection Data ◽  
Fine Grained ◽  
Reflection Data ◽  
Deposition Processes ◽  
Sea Fan ◽  
The Impact

Abstract. The effects of changes in slope gradient on deposition processes and architecture have been investigated in different deep-sea systems both in modern and ancient environments. However, the impact of subtle gradient changes (< 0.3∘) on sedimentary processes along deep-sea fans still needs to be clarified. The Ogooue Fan, located in the northeastern part of the Gulf of Guinea, extends over more than 550 km westwards of the Gabonese shelf and passes through the Cameroon volcanic line. Here, we present the first study of acoustic data (multibeam echosounder and 3.5 kHz, very high-resolution seismic data) and piston cores covering the deep-sea part of this West African system. This study documents the architecture and sedimentary facies distribution along the fan. Detailed mapping of near-seafloor seismic-reflection data reveals the influence of subtle slope gradient changes (< 0.2∘) along the fan morphology. The overall system corresponds to a well-developed deep-sea fan, fed by the Ogooue River sedimentary load, with tributary canyons, distributary channel–levee complexes and lobe elements. However, variations in the slope gradient due to inherited salt-related structures and the presence of several seamounts, including volcanic islands, result in a topographically complex slope profile including several ramps and steps. In particular, turbidity currents derived from the Gabonese shelf deposit cross several interconnected intra-slope basins located on the low gradient segments of the margin (< 0.3∘). On a higher gradient segment of the slope (0.6∘), a large mid-system valley developed connecting an intermediate sedimentary basin to the more distal lobe area. Distribution and thickness of turbidite sands is highly variable along the system. However, turbidite sands are preferentially deposited on the floor of the channel and the most proximal depositional areas. Core description indicates that the upper parts of the turbidity flows, mainly composed of fine-grained sediments, are found in the most distal depocenters.

New species of Tanaella Norman and Stebbing, 1886 (Crustacea: Tanaidacea: Tanaellidae) from the deep-sea off the Antarctic and the Angola Basin, with a key to the genus

Zootaxa ◽  
2004 ◽  
Vol 459 (1) ◽  
pp. 1 ◽  
Author(s):  
JÜRGEN GUERRERO-KOMMRITZ ◽  
MAGDALENA B½AÚEWICZ-PASZKOWYCZ
Keyword(s):  
New Species ◽  
Atlantic Ocean ◽  
Deep Sea ◽  
First Record ◽  
The Antarctic ◽  
Southern Atlantic Ocean

Three new deep-sea species in the genus Tanaella are described: two from the Antarctic (T. eltaninae sp. nov., T. kimi sp. nov.) and one from the Angola Basin (T. profunda sp. nov.). This is the first record of Tanaella in the deep-sea of the Antarctic and the southern Atlantic Ocean. A key to the 13 known species of the genus is provided.

scholarly journals The Ogooue Fan (Gabon): a modern example of deep-sea system on a complex sea-floor topography

2018 ◽  
Author(s):  
Salomé Mignard ◽  
Thierry Mulder ◽  
Philippe Martinez ◽  
Thierry Garlan
Keyword(s):  
Sea Level ◽  
Deep Sea ◽  
Sedimentary Facies ◽  
Turbidity Currents ◽  
Acoustic Data ◽  
Fine Grained ◽  
Longshore Drift ◽  
Volcanic Islands ◽  
Sea Fan ◽  
Channel Levees

Abstract. The Ogooue deep-sea Fan located in the northeastern part of the Gulf of Guinea expands over more than 550 km westwards of the Gabonese shelf and passes through the Cameroun volcanic line. Here are presented the first study of acoustic data (multibeam echosounder and 3.5 kHz seismic data) and piston cores covering the deep-sea part of this West African system. This study led to the construction of the sedimentary processes map of this area. The overall system corresponds to a well-developed mud-sand rich deep-sea fan, fed by the Ogooue River 'sedimentary load. This system presents the typical morphological elements of clastic slope apron: tributary canyons, distributary channel-levees systems and lobes elements. However, variations on the slope gradient cumulated with the presence of numerous seamounts, including volcanic islands and mud volcanoes, led to a more complex fan architecture and sedimentary facies distribution. In particular, turbidity currents derived from the Gabonese shelf deposit across several interconnected sedimentary sub-basins located on the low gradient segments of the margin. The repeated spill-overs of the most energetic turbidite flows have notably led to the incision of a large distal valley connecting an intermediate sedimentary basin to the more distal lobe area. The sedimentary facies repartition over the fan indicates that pelagic to hemipelagic sedimentation is dominant across the area. Distribution and thickness of turbidite sand beds is highly variable along the system, however turbidite sands preferentially deposit in the bottom of channel-levee systems and on the most proximal depositional areas. The most distal depocenters receive only the upper parts of the flows, which are composed of fine-grained sediments. The Ogooue deep-sea system is predominantly active during periods of low sea-level because canyon heads are separated from terrestrial sediment sources by the broad shelf. However, the northern part of this system appears active during sea-level highstands. This feature is one deeply incised canyon, the Cape Lopez canyon, located on a narrower part of the continental shelf has a different behaviour and receives sediments transported by the longshore drift.

Diatoms in surface sediments of the Zaire deep-sea fan (Se atlantic ocean) and their relation to overlying water masses

1987 ◽  
Vol 21 (3) ◽  
pp. 203-217 ◽  
Author(s):  
J.M Van Iperen ◽  
T.C.E Van Weering ◽  
J.H.F Jansen ◽  
A.J van Bennekom
Keyword(s):  
Atlantic Ocean ◽  
Deep Sea ◽  
Surface Sediments ◽  
Water Masses ◽  
Overlying Water ◽  
Sea Fan

scholarly journals Stratigraphic revision and reconstruction of the deep-sea fan of the Voirons Flysch (Voirons Nappe, Chablais Prealps)

2021 ◽  
Vol 114 (1) ◽  
Author(s):  
Jérémy Ragusa ◽  
Lina Maria Ospina-Ostios ◽  
Pascal Kindler ◽  
Mario Sartori
Keyword(s):  
Deep Sea ◽  
Distal Part ◽  
Accretionary Prism ◽  
Proximal Part ◽  
Late Eocene ◽  
Lithostratigraphic Units ◽  
Stratigraphic Record ◽  
Sea Fan ◽  
Stratigraphic Evolution ◽  
Depositional Setting

AbstractThe Voirons Flysch (Caron in Eclogae Geologicae Helvetiae 69:297–308, 1976), is a flysch sequence aggregated into the sedimentary accretionary prism of the Chablais and Swiss Prealps. Its palaeogeographic location is still debated (South Piemont or Valais realm). We herein present a stratigraphic revision of the westernmost unit of the former Gurnigel Nappe sensu Caron (Eclogae Geologicae Helvetiae 69:297–308, 1976): the Voirons Flysch. This flysch is subdivided into three lithostratigraphic units at the formation level (the Voirons Sandstone, the Vouan Conglomerate, the Boëge Marl), with an additional unit (Bruant Sandstone) of uncertain attribution, ranging from the early Eocene to probably the late Eocene. We further propose a new model of the depositional setting of the deep-sea of the Voirons Flysch based on palaeocurrent directions, the overall geometry and sedimentary features. This model depicts an eastward deflected deep-sea fan. The stratigraphic record of the proximal part of this fan is fairly complete in the Voirons area, whereas its most distal part is only represented by one small exposure of thinly bedded sandstones in the Fenalet quarry. The stratigraphic evolution of the Voirons Flysch shows two major disruptions of the detrital sedimentation at the transition between Voirons Sandstone—Vouan Conglomerate and Vouan Conglomerate—Boëge Marl. The cause of these disturbances has to be constrained in the framework of the palaeogeographic location of the Voirons Flysch.

The ancestral Mississippi drainage archived in the late Wisconsin Mississippi deep-sea fan

Geology ◽  
2016 ◽  
Vol 44 (6) ◽  
pp. 479-482 ◽  
Author(s):  
A. Fildani ◽  
M.P. McKay ◽  
D. Stockli ◽  
J. Clark ◽  
M.L. Dykstra ◽  
...  
Keyword(s):  
Deep Sea ◽  
Sea Fan
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