A Silurian Deep Sea Fan Deposit in Western Ireland and Its Bearing on the Nature of Turbidity Currents

1970 ◽  
Vol 78 (5) ◽  
pp. 509-522 ◽  
Author(s):  
David J. W. Piper
Keyword(s):  
Deep Sea ◽  
Turbidity Currents ◽  
Western Ireland ◽  
Sea Fan

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.

Deep Sea Fan Issues

2000 ◽  
Author(s):  
George Taft ◽  
Bilal Haq
Keyword(s):  
Bay Of Bengal ◽  
Deep Sea ◽  
Proximal Part ◽  
Indian Plate ◽  
Turbidity Currents ◽  
Ocean Drilling Program ◽  
Delta Front ◽  
Bengal Fan ◽  
History Of ◽  
Sea Fan

Deep sea fans occur along many continental margins. The Bengal Fan is the world's largest elongated submarine fan area, occupying over 3 x 106 km2 of seafloor in the Bay of Bengal. The Bay of Bengal is bordered by Sri Lanka, India, Bangladesh, Myanamar, the Andaman and Nicobar Islands, and Sumatra. The fan spans an area that is 2800-3000km in length and 830-1430 km in width. At the northern end of the Bay, the sediment cover is estimated to be more than 16 km in thickness (Curray and Moore, 1971, 1974, Moore et al., 1974). Recent drilling on the distal part of the fan just south of the equator during Ocean Drilling Program Leg 116 cored nearly 1 km of sediment without reaching hardrock basement (Cochran et al., 1990). The submarine feature of the Ninetyeast Ridge divides the fan into two major lobes, the main Bengal Fan and the eastern lobe, also known as the Nicobar Fan (Curray and Moore, 1974) (figure 19.1). The fan extends from 20°N latitude and, based on recent sedimentological and channel-system studies, to beyond 9°S latitude (Stow et al., 1990; Hübscher et al., 1997). The great size of the Bengal Fan is related to the history of the collision of the Indian tectonic plate with Eurasia and the subsequent uplift of the Himalayas. The first encounter of the northward-moving Indian Plate with the Asian mainland occurred around 50 million years (my) ago in the early Eocene Epoch (Haq, 1985). The first collision caused the initial uplift in the Himalayan region. Sedimentation in the bay is inferred to have started after this first collision, but extensive sedimentation probably did not begin until the early Miocene (ca. 17 my ago) after a major uplift in the Himalayas (Haq, 1985). Weathering and denudation of the Himalayas has furnished huge volumes of sediments that have built the Bengal Fan, supplied through the Ganges and Brahmaputra Rivers and their delta (figure 19.2). Sediments are transported largely by turbidity currents across the submerged continental terrace in the proximal part of the fan through a major delta-front canyon, also known as the Swatch-of-No-Ground. Currently, this canyon discharges its load into a single active channel that supplies sediment to the entire length of the fan.

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.

scholarly journals Fauna and habitat types driven by turbidity currents in the lobe complex of the Congo deep-sea fan

2017 ◽  
Vol 142 ◽  
pp. 167-179 ◽  
Author(s):  
Arunima Sen ◽  
Bernard Dennielou ◽  
Julie Tourolle ◽  
Aurélien Arnaubec ◽  
Christophe Rabouille ◽  
...  
Keyword(s):  
Deep Sea ◽  
Turbidity Currents ◽  
Habitat Types ◽  
Sea Fan

Lobe construction and sand/mud segregation by turbidity currents and debris flows on the western Nile deep-sea fan (Eastern Mediterranean)

2010 ◽  
Vol 229 (3) ◽  
pp. 124-143 ◽  
Author(s):  
S. Migeon ◽  
E. Ducassou ◽  
Y. Le Gonidec ◽  
P. Rouillard ◽  
J. Mascle ◽  
...  
Keyword(s):  
Deep Sea ◽  
Debris Flows ◽  
Eastern Mediterranean ◽  
Turbidity Currents ◽  
Sea Fan

scholarly journals A deep subaqueous fan depositional model for the Palaeoarchaean (3.46 Ga) Marble Bar Cherts, Warrawoona Group, Western Australia

2012 ◽  
Vol 149 (4) ◽  
pp. 743-749 ◽  
Author(s):  
NICOLAS OLIVIER ◽  
GILLES DROMART ◽  
NICOLAS COLTICE ◽  
NICOLAS FLAMENT ◽  
PATRICE REY ◽  
...  
Keyword(s):  
Mass Transport ◽  
Western Australia ◽  
Deep Sea ◽  
High Density ◽  
Turbidity Currents ◽  
Low Density ◽  
Depositional Model ◽  
Sea Fan ◽  
Pilbara Craton ◽  
Channel Systems

AbstractThe 3.46 Ga Marble Bar Chert Member of the East Pilbara Craton, Western Australia, is one of the earliest and best-preserved sedimentary successions on Earth. Here, we interpret the finely laminated thin-bedded cherts, mixed conglomeratic beds, chert breccia beds and chert folded beds of the Marble Bar Chert Member as the product of low-density turbidity currents, high-density turbidity currents, mass transport complexes and slumps, respectively. Integrated into a channel-levee depositional model, the Marble Bar Chert Member constitutes the oldest documented deep-sea fan on Earth, with thin-bedded cherts, breccia beds and slumps composing the outer levee facies tracts, and scours and conglomeratic beds representing the channel systems.

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.

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