Contourite depositional systems (CDS) represent the sedimentary records of paleoceanographic circ... more Contourite depositional systems (CDS) represent the sedimentary records of paleoceanographic circulation and paleoclimatic changes throughout the geological timescale. These records offer expanded but contingent information relative to their adjacent marine gateways, documenting changes in the intensity and the direction of modern-day and paleo-current pathways on multi-centennial, millennial and million-year timescales. This study investigates the late Miocene to Quaternary CDSs from the Gulf of Cadiz towards the West Iberian margin after the exit of the past Betic and Rifian corridors and most recent Strait of Gibraltar, the key gateways for the Mediterranean – Atlantic exchange trough time. A summary of the key results is presented as a representative study case for decoding the long- and short-term behaviour of oceanographic processes related to gateways and their associated overflows.In the study area, it is well known that the Mediterranean Outflow Water (MOW) has generated a complex CDS since the full opening of the Strait of Gibraltar in the early Pliocene (5.3 Ma). Recently, an ancient CDS has also been discovered in the late Miocene, which is separated from the Pliocene-Quaternary CDS by a period of quiescence representing the restriction of bottom water circulation across the Mediterranean-Atlantic exchange during the late Messinian (~6.4 - 5.3 Ma). The late Miocene CDS was established after the final closure of the Indian Gateway (IG) and the Neo-Tethys Ocean in the Middle Miocene, followed by the inception of the Mediterranean Sea (~13.8 - 11 Ma). The final closure of the IG conditioned a wide gateway configuration for the connection between the Mediterranean Sea and the Atlantic Ocean, with the full establishment of an anti-estuarine circulation similar to the present day as opposed to its previous situation.Interestingly, both the late Miocene and the Pliocene-Quaternary CDSs have a long common evolution that could be simplified into two stages, with an initial- and growth-drift stages. The late Miocene CDS is then buried under dominantly hemipelagic late Messinian (~6.4 - 5.3 Ma) deposits, whereas the buried-drift stage is absent for the Pliocene-Quaternary system due to the ongoing nature of the CDS’s evolution. The long-term development of these CDSs can be correlated with a coeval shallowing of sills, which determined a change from an outflow to an overflow setting across the gateways through time. These long-term variations (>5-10 My) in paleo-circulation are thus driven by the by the tectonic control on the evolution of oceanic gateways. The internal sedimentary architecture of the late Miocene and Pliocene-Quaternary CDSs indicates a complex stratigraphic stacking pattern of deposits bounded by internal discontinuities and hiatuses in response to the intermittent behaviour of the MOW at different temporal scales, which have been attributed to tectonic pulses, climatic and eustatic changes and oceanographic processes that have caused deepening/shoaling or weakening/strengthening of bottom currents through time, exerting a major effect on deepwater sedimentation and the benthic habitat.This project was funded by the JIP#1 within the framework of “The Drifters” Research Group at Royal Holloway University of London and related to the projects, CTM2016-75129-C3 (INPULSE) and PID2021-123825OB-I00 (ALGEMAR).
The analysis of multibeam bathymetric data and high-resolution seismic profiles in the Almeria Ma... more The analysis of multibeam bathymetric data and high-resolution seismic profiles in the Almeria Margin (NE Alboran Sea) allows the definition of three Systems of Valleys that act as Tributaries (SVT) to the Almeria Canyon: The Dalias SVT, in the canyon western margin, the Cata SVT to the East; and the Andarax SVT in the shelf and slope in front of Almeria. These system share some morphologic characteristics as the down-slope trend of the valleys and the dendritic pattern, with smaller valleys merging to larger ones that finally flow into the canyon. In contrast, the differences in morphological parameters as length, depth or sinuosity and the recent stratigraphy indicate that the origin and development of the three systems has been affected in a different way by the main controlling factors: sea-level fluctuations, tectonics and physiography.
Early Pleistocene Marine Isotope Stage (MIS)‐31 (1.081–1.062 Ma) is a unique interval of extreme ... more Early Pleistocene Marine Isotope Stage (MIS)‐31 (1.081–1.062 Ma) is a unique interval of extreme global warming, including evidence of a West Antarctic Ice Sheet (WAIS) collapse. Here we present a new 1,000‐year resolution, spanning 1.110–1.030 Ma, diatom‐based reconstruction of primary productivity, relative sea surface temperature changes, sea‐ice proximity/open ocean conditions and diatom species absolute abundances during MIS‐31, from the Scotia Sea (59°S) using deep‐sea sediments collected during International Ocean Discovery Program (IODP) Expedition 382. The lower Jaramillo magnetic reversal (base of C1r.1n, 1.071 Ma) provides a robust and independent time‐stratigraphic marker to correlate records from other drill cores in the Antarctic Zone of the Southern Ocean (AZSO). An increase in open ocean species Fragilariopsis kerguelensis in early MIS‐31 at 53°S (Ocean Drilling Program Site 1,094) correlates with increased obliquity forcing, whereas at 59°S (IODP Site U1537; this st...
Radio-density signal of bigradational sequences adjacent to the Southern Channel: a tomographic a... more Radio-density signal of bigradational sequences adjacent to the Southern Channel: a tomographic approach to contourite deposits in the the Gulf of Cádiz.
The study area is located close to the Strait of Gibraltar, adjacent to the "Proximal Scour and r... more The study area is located close to the Strait of Gibraltar, adjacent to the "Proximal Scour and ribbons sector" defined in the middle slope as part of the Gulf of Cadiz Contourite Depositional System (Hernández-Molina et al., 2006). The upper slope in this region is covered by plastered contourite drifts (Brackenridge et al., 2018) dissected by valleys on the upper slope, and two main channels (upper and lower) on the middle slope (Fig. 1).
The Western Mediterranean Sea is a natural laboratory to address questions about the formation an... more The Western Mediterranean Sea is a natural laboratory to address questions about the formation and evolution of continental margins and the relationship between surface and deep processes. The evaporites deposited during the late Miocene's Messinian Salinity Crisis (MSC) strongly impact its sedimentological and geomorphological evolution. Hereafter, we present a compilation of some of the main regional seismic stratigraphic markers throughout the Western Mediterranean Sea. We provide in xyz format (z in second twt) the original, not interpolated, points interpretation of the following horizons: i) Acoustic basement, ii) Base and Top of the MSC salt, also known as Mobile Unit (MU), iii) base Pliocene and iv) Seafloor. The available reflection seismic dataset, coming from a collaboration between French, Spanish, Algerian and Italian research institutes, covers most of the Western Mediterranean sub-basins with the exception of the Ligurian Basin. This compilation is currently the m...
Vazquez, J. T. ... et al.-- Submarine Canyon Dynamics in the Mediterranean and Tributary Seas - A... more Vazquez, J. T. ... et al.-- Submarine Canyon Dynamics in the Mediterranean and Tributary Seas - An integrated geological, oceanographic and biological perspective, 15-18 April 2015, Sorrento, Italy.-- 14 pages, 5 figures.-- This is a contribution of the Continental Margins Research Group (CMRG- 2009SGR1071, Generalitat de Catalunya), Geosciences Marine Research Group (GEMAR - lEO) and Littoral and Marine Geophysical and Geological Research Group (RNM 0328, PAIDI)
Llave, Estefania ... et. al.-- VIII Simposio sobre el Margen Iberico Atlantico (MIA15), del 21 al... more Llave, Estefania ... et. al.-- VIII Simposio sobre el Margen Iberico Atlantico (MIA15), del 21 al 23 de septiembre de 2015, Malaga.-- 4 pages, 1 figure
Proceedings of the International Ocean Discovery Program, 2021
This work is distributed under the Creative Commons Attribution 4.0 International (CC BY 4.0) lic... more This work is distributed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license. Contents 1 Background and objectives 2 Operations 6 Lithostratigraphy 14 Biostratigraphy 22 Paleomagnetism 37 Geochemistry 42 Physical properties 51 Stratigraphic correlation 58 Downhole measurements 63 Core-log-seismic integration 71 References
Multibeam bathymetric imagery and acoustic sub-bottom profiles are used to reveal distribution pa... more Multibeam bathymetric imagery and acoustic sub-bottom profiles are used to reveal distribution patterns of subsurface sedimentation in Dove Basin (Scotia Sea). The goals of the study are to determine the imprint of the inflow of deep Antarctic water masses from the Weddell Sea into the Scotia Sea, to establish the factors driving the styles of contourite deposition and to discern the relative contribution of alongslope versus downslope processes to the construction of the uppermost late Quaternary sedimentary record in the basin. The most significant morpho-sedimentary features in Dove Basin are linked to contouritic processes and to mass movements. Plastered drifts on the flanks of the basin constitute the most common contouritic deposits. Basement-controlled drifts on top of structural elevations are common along the central ridge, the central basin plain and scattered along the basin flanks. Sheeted drifts occur on top of adjacent banks or are restricted to the deep basin. In contrast, mounded drifts are poorly represented in Dove basin. A laterally extensive contouritic channel runs along the central ridge. Contouritic channels are also identified in the upper parts of the lateral banks and slopes. Numerous slide scars along the upper parts of the slopes evolve downslope into semitransparent lens-shaped bodies, with occasional development of across-slope channels. Semitransparent lenses occur intercalated within stratified deposits in the slopes of the basin, in the central ridge and in the deepest basin plain. The spatial arrangement of contouritic morphologies points to the influence of the water column structure and the basin physiography. In the eastern sub-basin, two different fractions (lower and upper) of Weddell Sea Deep Water (WSDW) leave an imprint on contourite deposits owing to the sloping interface between the two fractions. Contouritic influence is more subdued in the western sub-basin, and limited to the imprint of the lower WSDW. The upper parts of the surrounding banks are under the influence of deep-reaching Circumpolar waters (i.e., Lower Circumpolar Deep Water), which develops both depositional and erosional morphologies. The crosssection V-shaped morphology of the basin and the common occurrence of structural highs drive the predominance of plastered and basement-controlled drifts in the sediment record. The frequent alternation between contourites and downslope gravity-flow deposits is likely due to different processes associated with oversteepening in the basin, such as basement-controlled steep slopes, deformed drifts atop basement elevations, and the development of thick contouritic piles. Dove Basin is an example of a basin without mounded, plastered or mixed hybrid drifts in the transition between the lower slope and the deep basin, because the upper boundary of the deepest water mass-the Weddell Sea Deep Water-flows shallower along the middle slope. This fact underlines the relevance of the position and depth of water masses in shaping the morphology of the feet of slopes along continental margins.
International Ocean Discovery Program Preliminary Report, 2019
tween 400 and 2000 m water depth on the northern flank of an east-west trending trough off the Ch... more tween 400 and 2000 m water depth on the northern flank of an east-west trending trough off the Chilean continental shelf, is ideally situated to monitor millennial-to orbital-scale variability in the export of Antarctic Intermediate Water beneath the Subantarctic Front. During Expedition 382, we recovered continuously deposited sediments from this drift spanning the late Pleistocene (from ~0.78 Ma to recent) and from the late Pliocene (~3.1-2.6 Ma). These sites are expected to yield a wide array of paleoceanographic records that can be used to interpret past changes in the density structure of the Atlantic sector of the Southern Ocean, track migrations of the Subantarctic Front, and give insights into the role and evolution of the cold water route over significant climate episodes, including the following: • The most recent warm interglacials of the late Pleistocene and • The intensification of Northern Hemisphere glaciation.
Geological Society, London, Special Publications, 2019
This work uses seismic records to document and classify contourite features around the Iberian co... more This work uses seismic records to document and classify contourite features around the Iberian continental margin to determine their implications for depositional systems and petroleum exploration. Contourites include depositional features (separated, sheeted, plastered and confined drifts), erosional features (abraded surfaces, channels, furrows and moats) and mixed features (contourite terraces). Drifts generally show high- to moderate-amplitude reflectors, which are cyclically intercalated with transparent layers. Transparent layers may represent finer-grained deposits, which can serve as seal rocks. High-amplitude reflectors (HARs) are likely to represent sandier layers, which could form hydrocarbon reservoirs. HARs occur on erosive features (moats and channels), and are clearly developed on contourite terraces and overflow features. Most of the contourite features described here are influenced by Mediterranean water masses throughout their Pliocene and Quaternary history. They ...
Contourite depositional systems (CDS) represent the sedimentary records of paleoceanographic circ... more Contourite depositional systems (CDS) represent the sedimentary records of paleoceanographic circulation and paleoclimatic changes throughout the geological timescale. These records offer expanded but contingent information relative to their adjacent marine gateways, documenting changes in the intensity and the direction of modern-day and paleo-current pathways on multi-centennial, millennial and million-year timescales. This study investigates the late Miocene to Quaternary CDSs from the Gulf of Cadiz towards the West Iberian margin after the exit of the past Betic and Rifian corridors and most recent Strait of Gibraltar, the key gateways for the Mediterranean – Atlantic exchange trough time. A summary of the key results is presented as a representative study case for decoding the long- and short-term behaviour of oceanographic processes related to gateways and their associated overflows.In the study area, it is well known that the Mediterranean Outflow Water (MOW) has generated a complex CDS since the full opening of the Strait of Gibraltar in the early Pliocene (5.3 Ma). Recently, an ancient CDS has also been discovered in the late Miocene, which is separated from the Pliocene-Quaternary CDS by a period of quiescence representing the restriction of bottom water circulation across the Mediterranean-Atlantic exchange during the late Messinian (~6.4 - 5.3 Ma). The late Miocene CDS was established after the final closure of the Indian Gateway (IG) and the Neo-Tethys Ocean in the Middle Miocene, followed by the inception of the Mediterranean Sea (~13.8 - 11 Ma). The final closure of the IG conditioned a wide gateway configuration for the connection between the Mediterranean Sea and the Atlantic Ocean, with the full establishment of an anti-estuarine circulation similar to the present day as opposed to its previous situation.Interestingly, both the late Miocene and the Pliocene-Quaternary CDSs have a long common evolution that could be simplified into two stages, with an initial- and growth-drift stages. The late Miocene CDS is then buried under dominantly hemipelagic late Messinian (~6.4 - 5.3 Ma) deposits, whereas the buried-drift stage is absent for the Pliocene-Quaternary system due to the ongoing nature of the CDS’s evolution. The long-term development of these CDSs can be correlated with a coeval shallowing of sills, which determined a change from an outflow to an overflow setting across the gateways through time. These long-term variations (>5-10 My) in paleo-circulation are thus driven by the by the tectonic control on the evolution of oceanic gateways. The internal sedimentary architecture of the late Miocene and Pliocene-Quaternary CDSs indicates a complex stratigraphic stacking pattern of deposits bounded by internal discontinuities and hiatuses in response to the intermittent behaviour of the MOW at different temporal scales, which have been attributed to tectonic pulses, climatic and eustatic changes and oceanographic processes that have caused deepening/shoaling or weakening/strengthening of bottom currents through time, exerting a major effect on deepwater sedimentation and the benthic habitat.This project was funded by the JIP#1 within the framework of “The Drifters” Research Group at Royal Holloway University of London and related to the projects, CTM2016-75129-C3 (INPULSE) and PID2021-123825OB-I00 (ALGEMAR).
The analysis of multibeam bathymetric data and high-resolution seismic profiles in the Almeria Ma... more The analysis of multibeam bathymetric data and high-resolution seismic profiles in the Almeria Margin (NE Alboran Sea) allows the definition of three Systems of Valleys that act as Tributaries (SVT) to the Almeria Canyon: The Dalias SVT, in the canyon western margin, the Cata SVT to the East; and the Andarax SVT in the shelf and slope in front of Almeria. These system share some morphologic characteristics as the down-slope trend of the valleys and the dendritic pattern, with smaller valleys merging to larger ones that finally flow into the canyon. In contrast, the differences in morphological parameters as length, depth or sinuosity and the recent stratigraphy indicate that the origin and development of the three systems has been affected in a different way by the main controlling factors: sea-level fluctuations, tectonics and physiography.
Early Pleistocene Marine Isotope Stage (MIS)‐31 (1.081–1.062 Ma) is a unique interval of extreme ... more Early Pleistocene Marine Isotope Stage (MIS)‐31 (1.081–1.062 Ma) is a unique interval of extreme global warming, including evidence of a West Antarctic Ice Sheet (WAIS) collapse. Here we present a new 1,000‐year resolution, spanning 1.110–1.030 Ma, diatom‐based reconstruction of primary productivity, relative sea surface temperature changes, sea‐ice proximity/open ocean conditions and diatom species absolute abundances during MIS‐31, from the Scotia Sea (59°S) using deep‐sea sediments collected during International Ocean Discovery Program (IODP) Expedition 382. The lower Jaramillo magnetic reversal (base of C1r.1n, 1.071 Ma) provides a robust and independent time‐stratigraphic marker to correlate records from other drill cores in the Antarctic Zone of the Southern Ocean (AZSO). An increase in open ocean species Fragilariopsis kerguelensis in early MIS‐31 at 53°S (Ocean Drilling Program Site 1,094) correlates with increased obliquity forcing, whereas at 59°S (IODP Site U1537; this st...
Radio-density signal of bigradational sequences adjacent to the Southern Channel: a tomographic a... more Radio-density signal of bigradational sequences adjacent to the Southern Channel: a tomographic approach to contourite deposits in the the Gulf of Cádiz.
The study area is located close to the Strait of Gibraltar, adjacent to the "Proximal Scour and r... more The study area is located close to the Strait of Gibraltar, adjacent to the "Proximal Scour and ribbons sector" defined in the middle slope as part of the Gulf of Cadiz Contourite Depositional System (Hernández-Molina et al., 2006). The upper slope in this region is covered by plastered contourite drifts (Brackenridge et al., 2018) dissected by valleys on the upper slope, and two main channels (upper and lower) on the middle slope (Fig. 1).
The Western Mediterranean Sea is a natural laboratory to address questions about the formation an... more The Western Mediterranean Sea is a natural laboratory to address questions about the formation and evolution of continental margins and the relationship between surface and deep processes. The evaporites deposited during the late Miocene's Messinian Salinity Crisis (MSC) strongly impact its sedimentological and geomorphological evolution. Hereafter, we present a compilation of some of the main regional seismic stratigraphic markers throughout the Western Mediterranean Sea. We provide in xyz format (z in second twt) the original, not interpolated, points interpretation of the following horizons: i) Acoustic basement, ii) Base and Top of the MSC salt, also known as Mobile Unit (MU), iii) base Pliocene and iv) Seafloor. The available reflection seismic dataset, coming from a collaboration between French, Spanish, Algerian and Italian research institutes, covers most of the Western Mediterranean sub-basins with the exception of the Ligurian Basin. This compilation is currently the m...
Vazquez, J. T. ... et al.-- Submarine Canyon Dynamics in the Mediterranean and Tributary Seas - A... more Vazquez, J. T. ... et al.-- Submarine Canyon Dynamics in the Mediterranean and Tributary Seas - An integrated geological, oceanographic and biological perspective, 15-18 April 2015, Sorrento, Italy.-- 14 pages, 5 figures.-- This is a contribution of the Continental Margins Research Group (CMRG- 2009SGR1071, Generalitat de Catalunya), Geosciences Marine Research Group (GEMAR - lEO) and Littoral and Marine Geophysical and Geological Research Group (RNM 0328, PAIDI)
Llave, Estefania ... et. al.-- VIII Simposio sobre el Margen Iberico Atlantico (MIA15), del 21 al... more Llave, Estefania ... et. al.-- VIII Simposio sobre el Margen Iberico Atlantico (MIA15), del 21 al 23 de septiembre de 2015, Malaga.-- 4 pages, 1 figure
Proceedings of the International Ocean Discovery Program, 2021
This work is distributed under the Creative Commons Attribution 4.0 International (CC BY 4.0) lic... more This work is distributed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license. Contents 1 Background and objectives 2 Operations 6 Lithostratigraphy 14 Biostratigraphy 22 Paleomagnetism 37 Geochemistry 42 Physical properties 51 Stratigraphic correlation 58 Downhole measurements 63 Core-log-seismic integration 71 References
Multibeam bathymetric imagery and acoustic sub-bottom profiles are used to reveal distribution pa... more Multibeam bathymetric imagery and acoustic sub-bottom profiles are used to reveal distribution patterns of subsurface sedimentation in Dove Basin (Scotia Sea). The goals of the study are to determine the imprint of the inflow of deep Antarctic water masses from the Weddell Sea into the Scotia Sea, to establish the factors driving the styles of contourite deposition and to discern the relative contribution of alongslope versus downslope processes to the construction of the uppermost late Quaternary sedimentary record in the basin. The most significant morpho-sedimentary features in Dove Basin are linked to contouritic processes and to mass movements. Plastered drifts on the flanks of the basin constitute the most common contouritic deposits. Basement-controlled drifts on top of structural elevations are common along the central ridge, the central basin plain and scattered along the basin flanks. Sheeted drifts occur on top of adjacent banks or are restricted to the deep basin. In contrast, mounded drifts are poorly represented in Dove basin. A laterally extensive contouritic channel runs along the central ridge. Contouritic channels are also identified in the upper parts of the lateral banks and slopes. Numerous slide scars along the upper parts of the slopes evolve downslope into semitransparent lens-shaped bodies, with occasional development of across-slope channels. Semitransparent lenses occur intercalated within stratified deposits in the slopes of the basin, in the central ridge and in the deepest basin plain. The spatial arrangement of contouritic morphologies points to the influence of the water column structure and the basin physiography. In the eastern sub-basin, two different fractions (lower and upper) of Weddell Sea Deep Water (WSDW) leave an imprint on contourite deposits owing to the sloping interface between the two fractions. Contouritic influence is more subdued in the western sub-basin, and limited to the imprint of the lower WSDW. The upper parts of the surrounding banks are under the influence of deep-reaching Circumpolar waters (i.e., Lower Circumpolar Deep Water), which develops both depositional and erosional morphologies. The crosssection V-shaped morphology of the basin and the common occurrence of structural highs drive the predominance of plastered and basement-controlled drifts in the sediment record. The frequent alternation between contourites and downslope gravity-flow deposits is likely due to different processes associated with oversteepening in the basin, such as basement-controlled steep slopes, deformed drifts atop basement elevations, and the development of thick contouritic piles. Dove Basin is an example of a basin without mounded, plastered or mixed hybrid drifts in the transition between the lower slope and the deep basin, because the upper boundary of the deepest water mass-the Weddell Sea Deep Water-flows shallower along the middle slope. This fact underlines the relevance of the position and depth of water masses in shaping the morphology of the feet of slopes along continental margins.
International Ocean Discovery Program Preliminary Report, 2019
tween 400 and 2000 m water depth on the northern flank of an east-west trending trough off the Ch... more tween 400 and 2000 m water depth on the northern flank of an east-west trending trough off the Chilean continental shelf, is ideally situated to monitor millennial-to orbital-scale variability in the export of Antarctic Intermediate Water beneath the Subantarctic Front. During Expedition 382, we recovered continuously deposited sediments from this drift spanning the late Pleistocene (from ~0.78 Ma to recent) and from the late Pliocene (~3.1-2.6 Ma). These sites are expected to yield a wide array of paleoceanographic records that can be used to interpret past changes in the density structure of the Atlantic sector of the Southern Ocean, track migrations of the Subantarctic Front, and give insights into the role and evolution of the cold water route over significant climate episodes, including the following: • The most recent warm interglacials of the late Pleistocene and • The intensification of Northern Hemisphere glaciation.
Geological Society, London, Special Publications, 2019
This work uses seismic records to document and classify contourite features around the Iberian co... more This work uses seismic records to document and classify contourite features around the Iberian continental margin to determine their implications for depositional systems and petroleum exploration. Contourites include depositional features (separated, sheeted, plastered and confined drifts), erosional features (abraded surfaces, channels, furrows and moats) and mixed features (contourite terraces). Drifts generally show high- to moderate-amplitude reflectors, which are cyclically intercalated with transparent layers. Transparent layers may represent finer-grained deposits, which can serve as seal rocks. High-amplitude reflectors (HARs) are likely to represent sandier layers, which could form hydrocarbon reservoirs. HARs occur on erosive features (moats and channels), and are clearly developed on contourite terraces and overflow features. Most of the contourite features described here are influenced by Mediterranean water masses throughout their Pliocene and Quaternary history. They ...
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