Origin of morphological depressions in the Guadalquivir Bank area (Gulf of Cadiz middle slope)

Origin of morphological depressions in the Guadalquivir Bank area (Gulf of Cadiz middle slope)

35th International Geological Congress, 27 August - 4 September 2016,Cape Town, South Africa, 1 page

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Main Authors: García, Marga, Hernández-Molina, Francisco J., Alonso, Belén, Vázquez, Juan Tomás, Ercilla, Gemma, Llave, Estefanía, Casas, David
Format: comunicación de congreso biblioteca
Published: 2016-08-27
Online Access:http://hdl.handle.net/10261/172051
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institution ICM ES
collection DSpace
country España
countrycode ES
component Bibliográfico
access En linea
databasecode dig-icm-es
tag biblioteca
region Europa del Sur
libraryname Biblioteca del ICM España
description 35th International Geological Congress, 27 August - 4 September 2016,Cape Town, South Africa, 1 page
format comunicación de congreso
author García, Marga
Hernández-Molina, Francisco J.
Alonso, Belén
Vázquez, Juan Tomás
Ercilla, Gemma
Llave, Estefanía
Casas, David
spellingShingle García, Marga
Hernández-Molina, Francisco J.
Alonso, Belén
Vázquez, Juan Tomás
Ercilla, Gemma
Llave, Estefanía
Casas, David
Origin of morphological depressions in the Guadalquivir Bank area (Gulf of Cadiz middle slope)
author_facet García, Marga
Hernández-Molina, Francisco J.
Alonso, Belén
Vázquez, Juan Tomás
Ercilla, Gemma
Llave, Estefanía
Casas, David
author_sort García, Marga
title Origin of morphological depressions in the Guadalquivir Bank area (Gulf of Cadiz middle slope)
title_short Origin of morphological depressions in the Guadalquivir Bank area (Gulf of Cadiz middle slope)
title_full Origin of morphological depressions in the Guadalquivir Bank area (Gulf of Cadiz middle slope)
title_fullStr Origin of morphological depressions in the Guadalquivir Bank area (Gulf of Cadiz middle slope)
title_full_unstemmed Origin of morphological depressions in the Guadalquivir Bank area (Gulf of Cadiz middle slope)
title_sort origin of morphological depressions in the guadalquivir bank area (gulf of cadiz middle slope)
publishDate 2016-08-27
url http://hdl.handle.net/10261/172051
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spelling dig-icm-es-10261-1720512019-10-03T07:35:00Z Origin of morphological depressions in the Guadalquivir Bank area (Gulf of Cadiz middle slope) García, Marga Hernández-Molina, Francisco J. Alonso, Belén Vázquez, Juan Tomás Ercilla, Gemma Llave, Estefanía Casas, David 35th International Geological Congress, 27 August - 4 September 2016,Cape Town, South Africa, 1 page Swath bathymetry and high resolution seismic datasets evidence the widespread occurrence of morphological depressions of different scales in continental margins. Their origin is related to a number of processes, such as fluid escape, collapses or reworking of bedforms by turbidity currents. In this work we study the origin of morphological depressions, escarpments and a major channel on the Guadalquivir Bank uplifted area (Gulf of Cadiz middle slope) in relation to bottom currents. The study area is located on the depositional sector of the Gulf of Cadiz Contourite System [1]. It is characterized by mounded and elongated contourite drifts at the foot of the upper slope and extensive sheeted drifts on the middle slope that result from the activity of the Mediterranean Outflow Water (MOW). The Bartolomeu Dias and Faro Sheeted Drift (SD) occur north of the Guadalquivir Bank and are separated by the Diego Cao Channel. The Diego Cao channel is 4-5 km wide and has a NW-SE trend. In Parasound profiles it shows truncated reflections on the NE flank and layered reflections on the SW flank. It has been previously interpreted as a Contourite Channel [1]. Amphitheatre-shaped escarpments occur along the SE limit of the Bartolomeu Dias SD plateau. They are 0.5-5.5 km in diameter, 20-80 m deep and produce a terraced-shaped profile. They are interpreted as slide scars [2]. Circular-elliptical depressions occur on the Bartolomeu Dias S D plateau at depths of 640-780 m. They are aligned parallel to the SW rim of the Diego Cao Channel along about 12 km [2]. Depressions are irregular in shape, 1-2.2 km in diameter and 15-90 m deep. Parasound profiles show wavy, irregular parallel reflections with lateral discontinuities and truncations. The correlation in the depressions area with the regional stratigraphy [3] allows identifying two main Quaternary units (QI and QII) and the boundaries corresponding to the Base of Quaternary and the Middle Pleistocene (MPD). The Pliocene to Lower Quaternary record displays mounded bodies and associated depressions that evolve from single to multiple systems. The MPD is an erosional surface underlying the depressions that displays a step-like profile. The QII has an irregular, wavy, cut-and-fill seismic character. The morphological depressions are interpreted as the result of the interplay between oceanographic, mass-wasting and tectonic processes and occurred in four stages: 1) Weak MOW circulation produced the onset of a proto-Diego Cao contourite moat by interaction with structural features of the Guadalquivir Bank (Lower Pliocene); 2) Enhanced MOW and increased deformation created a multi-crest drift and moat system (Upper Pliocene-Early Quaternary); 3) Enhanced tectonic activity provoked widespread mass-wasting along the sheeted drifts rims, opening a gap in the bank uplift and originating the erosive surface as slide escarpments under the present-day Diego Cao channel western rim (Mid Pleistocene); 4) Final stage (Late Quaternary). The Intermediate Branch of the MOW started flowing through the deep gateway and a separated contourite drift started depositing over the erosional surface formed by the slide scars. The interaction between the bottom current and this irregular basal surface created the depressions as the drift was being deposited. In this scheme, the Diego Cao channel would have acted as a contourite moat since the Lower Pliocene, and not as a merely erosional contourite channel as previously interpreted Peer Reviewed 2018-11-09T11:08:47Z 2018-11-09T11:08:47Z 2016-08-27 2018-11-09T11:08:48Z comunicación de congreso http://purl.org/coar/resource_type/c_5794 35th International Geological Congress (2016) http://hdl.handle.net/10261/172051 https://www.americangeosciences.org/igc/15174 Sí none

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