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.

Origin of megarhythms in flysch sequences of the Quebec Appalachians

1979 ◽  
Vol 16 (7) ◽  
pp. 1518-1523 ◽  
Author(s):  
Jean Lajoie
Keyword(s):  
Deep Sea ◽  
Source Area ◽  
Rock Composition ◽  
Middle Cambrian ◽  
Late Cambrian ◽  
External Domain ◽  
Vertical Evolution ◽  
Metamorphic Terranes ◽  
Sea Fan ◽  
Stratigraphic Evolution

The cyclic and positive sequences observed in the External Domain of the Quebec Appalachians between L'IsIet and Grosses Roches have been interpreted as facies of deep-sea fans that result from progradation. In these conglomerate-bearing sequences, the composition of the detritus changes up-section, which suggests that uplift of the source area played an important role in their vertical evolution. In early and (or) Middle Cambrian time, the source consisted of sedimentary, igneous, and metamorphic terranes. This provenance was rejuvenated in Late Cambrian – Early Ordovician time, and the Lower – Middle Cambrian shelf wa.s uplifted. The stratigraphic evolution of composition observed in these flysch sequences cannot be explained by deep-sea fan progradation.In recent years the general trend in flysch-sequence analysis has been away from tectonic and towards sedimentological interpretations. The stratigraphic evolution of flysch sequences may be due to both tectonic and sedimentary processes. Studies of rock composition, generally neglected by most workers, could be used to make the distinction.

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.

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

scholarly journals Relative Abundance and Diversity of Bacterial Methanotrophs at the Oxic–Anoxic Interface of the Congo Deep-Sea Fan

2017 ◽  
Vol 8 ◽  
Author(s):  
Sandrine Bessette ◽  
Yann Moalic ◽  
Sébastien Gautey ◽  
Françoise Lesongeur ◽  
Anne Godfroy ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Deep Sea ◽  
Abundance And Diversity ◽  
Sea Fan

Retrospective analysis of the appendiceal neoplasms: sampling technique may influence neoplasm detection

2021 ◽  
pp. postgradmedj-2021-141244
Author(s):  
Gizem Issin ◽  
Fatih Demir ◽  
Hasan Aktug Simsek ◽  
Diren Vuslat Cagatay ◽  
Mahir Tayfur ◽  
...  
Keyword(s):  
Retrospective Analysis ◽  
Distal Part ◽  
Histopathological Examination ◽  
Small Diameter ◽  
Sampling Technique ◽  
Proximal Part ◽  
Longitudinal Section ◽  
Appendiceal Neoplasms ◽  
Macroscopic Findings ◽  
Distal Section

Background and aimsAppendiceal neoplasms are uncommon entities that are usually determined incidentally during the histopathological examination. Different techniques used for the macroscopic sampling of appendectomy material may affect the determinating neoplasms.Materials and methodsH&E-stained slides of 1280 cases who underwent appendectomy between 2013 and 2018 were reviewed retrospectively for histopathological features.ResultsNeoplasms were determined in 28 cases (3.09%); 1 lesion was observed in the proximal part of the appendix, 1 covering the entire length from proximal to distal and 26 in the distal part. In the 26 cases that observed in the distal part, the lesion was seen on both sides of the longitudinal section of the distal appendix in 20 cases, while it was seen on only one distal longitudinal section in the remaining 6 cases.ConclusionThe vast majority of appendiceal neoplasms are seen in the distal part of the appendix, and, in some cases, neoplasms might be seen on only one side of the distal section. Sampling only one-half of the distal part of the appendix, where tumours are most often observed, could result in some neoplasms being missed. Therefore, sampling the whole distal part would be more beneficial to determine small diameter tumours that do not create macroscopic findings.

Two new species of Cossura (Cossuridae, Annelida) from the terminal lobes of the Congo River deep-sea fan

2017 ◽  
Vol 97 (5) ◽  
pp. 881-888
Author(s):  
Anna Zhadan
Keyword(s):  
New Species ◽  
Deep Sea ◽  
Anterior Margin ◽  
Posterior Part ◽  
Entire Body ◽  
Congo River ◽  
Two New Species ◽  
Dark Pigmentation ◽  
Sea Fan ◽  
Scanning Electron

Two new species of Cossura Webster & Benedict, 1887 were found in material collected during sampling from the terminal lobes of the Congo deep-sea fan. They were described using light and scanning electron microscopy. Cossura platypus sp. nov. has 15–17 thoracic chaetigers, a prostomium longer than it is wide, with a widely rounded anterior margin, an abruptly expanded posterior prostomial ring the same length as the peristomium, without a mid-ventral notch, a branchial filament attached to the midlength of chaetiger 3, and a pygidium with three anal cirri. Cossura platypus sp. nov. is similar to C. brunnea Fauchald, 1972 but differs in the shape of the prostomium, which is widely rounded anteriorly in C. platypus sp. nov. and is broadly triangular in C. brunnea; furthermore, C. platypus sp. nov.is uniformly pale, whereas C. brunnea has dark pigmentation. Cossura candida Hartman, 1955 differs from C. platypus sp. nov. in the conical shape of the prostomium and 24–35 thoracic chaetigers. Cossura flabelligera sp. nov. has 16–19 thoracic chaetigers, a conical prostomium, and a branchial filament arising from the posterior part of chaetiger 2; the entire body, including the chaetae, is covered by a thick mucous sheath similar to the tunic of flabelligerids. Cossura flabelligera sp. nov. resembles C. longocirrata Webster & Benedict, 1887 in the position of the branchial filament, the shape of the prostomium, and the number of thoracic chaetigers; it differs in having a thick mucous sheath. This character seems to be unique for the Cossuridae.

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