This paper presents an analysis of the combined influence of along-slope sediment transport and o... more This paper presents an analysis of the combined influence of along-slope sediment transport and off-bank sediment export from the Little Bahama Bank (LBB) to the periplatform sediment wedge of the northwestern part of the slope over the last 424 ka. The LBB northwestern slope is divided in (i) a plateau-like structure (margin) at ~ 40 m water depth over at least 4 km parallel to the edge of the LBB; (ii) the uppermost slope with a mean slope angle of ~1.15° from 40 to 300 m water depth; (iii) the upper slope with slope angle of ~0.7 from 300 to 650 m water depth, (iv) the middle slope with slope angle of ~ 1.2, from 650 to 800 m water depth, and (v) the lower slope with slope angle of b~0.5, from 800 to 900 m water depth. The uppermost slope, the upper slope, and the middle slope of the northwestern LBB were characterized by periplatform oozes that became more diluted with pelagic sediment toward the distal part of the slope. This sediment distribution of the northwestern LBB slope varied significantly over times according to the flooded surface of the LBB. The major flooding periods are related to the highest Relative Sea Level (RSL) (N−6 m) that occurred during interglacial periods, the highest sedimentation rates (10–30 cm/ka) and the finest sediment facies were found on the slope. During interglacial periods when RSL b −6 m, LBB was emerged but bank margins were still flooded and correspond to intermediate sedimentation rates (a few to 10 cm/ka) on the slope. Finally, during glacial periods (RSL b − 90 m), LBB was emerged (including its margins), sedimentation rates on the slope dropped to a few mm/ka associated to coarser sediment facies. Off-bank-transported sediment is the main sediment supply during sea-level highstands, occurring preferentially during three major periods of LBB flooding over the last 424 ka: marine isotopic stages 1, 5e and 11. During sea-level lowstands, shallow carbonate production was very low but could develop over a 4 km-wide plateau-like structure when RSL was above −40 m. The regional Antilles Current affected the sea floor along the northwestern LBB slope and influenced coral mound distribution as well as sediment facies and sequences along the upper and middle slopes (300–800 m). During glacial periods, the stronger influence of the Antilles Current upon the along-slope sedimentation promoted diagenesis via the development of indurated nodules in the upper slope (~400 m water depth). It also encouraged bi-gradational sequences showing a coarsening-up unit followed by a fining-up unit along the middle slope (~800 m water depth) that is thoroughly bioturbated. The characteristics of these contourite sequences were similar to those described in siliciclastic environments, but in contrast were condensed with low sedimentation rates over long (glacial) periods.
The Messinian is one of the strongest biogenic silica accumulation periods in the world and more ... more The Messinian is one of the strongest biogenic silica accumulation periods in the world and more particularly in the Mediterranean, where it is marked by an important diatomitic sedimentation. In the Boudinar basin (Morocco north-Eastern, Western Mediterranean), ...
Évolution des environnements littoraux du bassin de Melilla-Nador (Nord-Est Maroc) au Messinien s... more Évolution des environnements littoraux du bassin de Melilla-Nador (Nord-Est Maroc) au Messinien supérieur entre 6,0 et 5,77 Ma Evolution of Melilla-Nador basin (NE Morocco) littoral environments during late Messinian between 6.0 and 5.77 Ma Résumé L'étude de dépôts littoraux d'âge Messinien supérieur (ensemble E2 = « Terminal Carbonate Complex ») du Bassin de Melilla-Nador (Maroc) a permis de caractériser l'évolution des environnements entre 6,0 et 5,77 Ma environ, soit durant une période considérée comme contemporaine du début de la « crise de salinité messinienne ». L'étude et l'approche statistique de l'analyse pétrographique ont permis de préciser la dynamique sédimentaire des plates-formes et, en intégrant la géométrie observée des dépôts, de proposer des modèles reconstituant les milieux de dépôt. Les dépôts de l'ensemble E2 du bassin de Melilla-Nador se caractérisent par une évolution progressive, sans rupture majeure, des environnements littoraux en deux épisodes majeurs d'ouverture-comblement. Le premier correspond à l'édification d'un complexe récifal entre 6,0 et 5,85 Ma ; le second, entre 5,85 et 5,77 Ma, au développement d'une rampe oolitique mixte au cours du comblement progressif du bassin de Melilla-Nador. La comparaison avec le bassin de Sorbas (Espagne) montre une évolution très proche des environnements littoraux au Messinien supérieur, qui pourrait être utilisée comme outil de corrélation. Abstract This study of late Messinian deposits (E2 = TCC) from Melilla-Nador carbonate complex (Morocco) allowed us to characterize the environmental evolution between 6.0 and 5.77 Ma, which is a period considered as contemporaneous of the onset and development of the " messinian salinity crisis ". A statistical approach coupled together with classical petrographic study allows us to constrain the sedimentary dynamic of platforms and to propose deposition environment models. The Melilla-Nador platforms E2 deposits show a progressive continuous evolution of littoral environments in two major stages of available space creation and infill. The first stage corresponds to the build up of a reef complex between 6.0 and 5.85 Ma then the second stage, between 5.85 and 5.77 Ma, corresponds to the development of a mixed oolitic shallow ramp during the progressive infill of Melilla-Nador basin. The comparison with the Sorbas basin (Spain) TCC deposits exhibits a very close evolution of late Messinian littoral environments, which could be used as a correlation tool.
Le Messinien représente une des périodes de forte accumulation de silice biogénique dans le monde... more Le Messinien représente une des périodes de forte accumulation de silice biogénique dans le monde et plusparticulì erement en Méditerranée, o` u il est marqué par une importante sédimentation diatomitique. Dans le bassin de Boudinar (Maroc nord-oriental, Méditerranée occidentale), la coupe de Sidi Haj Youssef, localisée au pied du volcan de Ras Tarf, présente sur environ 100 m d'´ epaisseur une série argilo-marneuse dans laquelle s'intercalent douze niveaux diatomitiques de puissance variable. Effectuée pour lapremì ere fois en détail, l'´ etude microfloristique de diatomées, portant sur 86échantillons, a permis de reconnaˆıtre 50 genres de diatomées (24 des centriques et 26 des pennées) représentés par 185 espèces (75 espèces des centriques et 110 espèces des pennées). Pour chaqué echantillon un comptage de 400 individus a ´ eté effectué permettant de déterminer la fréquence relative de chaque taxon au sein de l'assemblage de diatomées. Ainsi, plusieurs assemblages ontété définis par la dominance des espèces suivantes : Coscinodiscus marginatus, Actinoptychus senarius, Thalassionema nitzschioides, Actinocyclus curvatulus, Thalassiothrix longissima, Rhizosolenia styliformis et Actinocyclus ehrenbergii. Ces assemblages témoignent d'un milieu marin littoral en communication avec la mer ouverte. L'abondance des espèces d'eaux froides vers la base et le sommet de la coupe traduit de largeséchanges du bassin avec l'océan atlantique au Messinien. La dominance des taxons comme Thalassionema nitzschioides et/ou Thalassiothrix longissima indique des périodes de forte productivité pouvantêtre reliée au fonctionnement d'upwellings. Abstract The Messinian is one of the strongest biogenic silica accumulation periods in the world and more particularly in the Mediterranean, where it is marked by an important diatomitic sedimentation. In the Boudinar basin (Morocco northEastern , Western Mediterranean), the section of Sidi Haj Youssef, localised near the volcano of Ras Tarf, has approximately 100 m thickness of clayey-marly series in which 12 diatomitic levels of variable thickness are intercalated. The microfloristic study of diatoms on 86 samples, carried out in detail for the first time, made it possible to recognize 50 genus of diatoms (24 of centric and 26 of pennate) represented by 185 species (75 species of centric and 110 species of pennate). Four hundred individuals were taken from each sample to determine the relative frequency of each taxon within the diatoms assemblages. Thus, several assemblages were defined by the predominance of the following species: Coscinodiscus marginatus, Actinoptychus senarius, Thalassionema nitzschioides, Actinocyclus curvatulus, Thalassiothrix longissima, Rhizosolenia styliformis and Actinocyclus ehrenbergii. These diatoms assemblages display a littoral marine environment in communication with the opened sea. The abundance of the cold water species towards the base and the top of the * Auteur correspondant.
... Paris Bierville, 1996)G. Bonaduce, D. Barra and G. Aiello, The areal and bathymetrical dist... more ... Paris Bierville, 1996)G. Bonaduce, D. Barra and G. Aiello, The areal and bathymetrical distribution of the genus Henryhowella Puri (Ostracoda) in ... J. Civis, J. De Porta and J. Martinell, Bioestratigrafia del Messiniense de la rambla de Arejos (Almeria), Abstracts of the papers ...
Egu General Assembly Conference Abstracts, May 1, 2014
The Bahamian Banks are a classic study area for carbonate sedimentation because it provides many ... more The Bahamian Banks are a classic study area for carbonate sedimentation because it provides many modern analogues for ancient limestones. Several sedimentary and seismic dataset collected during oceanographic research cruises (including ODP expeditions) have revealed significant accumulation rates along the slopes of the slopes of the Bahama Banks. In this work, we focus on the major sedimentary body of the northwestern slope of the Little Bahama Bank (LBB), the second largest carbonate bank of the Bahamian archipelago. Our main topic is a better understanding of the export processes from the bank to the northern slope of the LBB, exposed to the prevalent winds (windward side), and of the sediment deposition related to the regional Antilles Current. Analyses of two marine cores allow to determine the sediment sources (nature and origin of the particles) and to generate a high-resolution stratigraphic model. Those two cores (CARKS-20 and CARKS-21) are located along the western side of the northern slope of the LBB and have been collected during the CARAMBAR cruise (2010). CARKS-21 penetrates the wedge of this major sedimentary body over 12 m. CARKS-20 penetrates the same sedimentary body in its thickest part over 13.25 m. The stratigraphical methods include faunal and floral analyses (planktonic foraminifera and coccoliths), radiometric dating, XRF analyses and isotope stratigraphy. The sedimentary analyses encompass spectrophotocolorimetry and grain-size measurements, indurated thin sections petrographical study and identification of bioclasts. Stratigraphical results from core CARKS-21 allow to consider long-term climatic trends extending from present to the marine isotope stage (MIS) 11 (424 kyr, from the top to 9.3 m), and highlight perturbation in the sedimentation from 9.3 to 12 m (from MIS 12 to MIS 25). Higher resolutions are highlighted in core CARKS-20 which extends from MIS 1 to MIS 11. Glacial periods and sea-level lowstands corresponding to exposure of the bank are related to low production and exportation of sediment. These periods are characterized by reduced deposits showing a coarsening-up unit followed by a finning-up unit (bigradational sequences) and are associated with allochtonous particles constituted by phosphatized foraminiferal tests and pteropods shells. From MIS 1 to MIS 11, interglacial periods are well developed and exhibit higher sediment rates (e.g. ~ 5 cm/kyr in CARKS-20). Three clay-rich beds have been observed and the two most recent one are well dated and correspond to a part of MIS 7 and MIS 11 in both cores. The oldest bed (only found in core CARKS-21) is older than MIS 15. Off-bank processes are the major sedimentary processes during sea-level highstands, whereas current-related deposits dominate during sea-level lowstands in the northern Bahamas slope at least over the last 424 kyr. Clay-rich deposits may be related to a slowdown of currents, allowing clay-size particle settling on the contouritic system, and/or an increase of clay production and export from continental areas during a short period of MIS 7, MIS 11 and around MIS 15 - 25. Phosphatized particles result from a phase of early diagenesis concomitant with transport in the basin by the Antilles Current.
... d'Algérie et des régions méditerranéenne avoisinantes (Cita et al. 1968 ; Mazzola 19... more ... d'Algérie et des régions méditerranéenne avoisinantes (Cita et al. 1968 ; Mazzola 1971 ; Cita 1975 ; Iaccarino 1985 ; Hilgen et al. 2000b , 2003). CADRE GÉOGRAPHIQUE ET GÉOLOGIQUE Le Djebel Diss (Fig. 2) est situé à l'extrémité sud-occidentale des monts du Dahra, sur ...
Marine faunas have been recently found interbedded in the Messinian gypsum of Los Yesos, in the S... more Marine faunas have been recently found interbedded in the Messinian gypsum of Los Yesos, in the Sorbas Basin (SE Spain). More than 80 species have been identified, including molluscs, echinoids, foraminifers, ostracods, crustaceans and bryozoans. Several specimens from these exceptional marine fossils are figured for the first time. The palaeoecological analysis of these fossils show that their environment of deposit
This paper presents an analysis of the combined influence of along-slope sediment transport and o... more This paper presents an analysis of the combined influence of along-slope sediment transport and off-bank sediment export from the Little Bahama Bank (LBB) to the periplatform sediment wedge of the northwestern part of the slope over the last 424 ka. The LBB northwestern slope is divided in (i) a plateau-like structure (margin) at ~ 40 m water depth over at least 4 km parallel to the edge of the LBB; (ii) the uppermost slope with a mean slope angle of ~1.15° from 40 to 300 m water depth; (iii) the upper slope with slope angle of ~0.7 from 300 to 650 m water depth, (iv) the middle slope with slope angle of ~ 1.2, from 650 to 800 m water depth, and (v) the lower slope with slope angle of b~0.5, from 800 to 900 m water depth. The uppermost slope, the upper slope, and the middle slope of the northwestern LBB were characterized by periplatform oozes that became more diluted with pelagic sediment toward the distal part of the slope. This sediment distribution of the northwestern LBB slope varied significantly over times according to the flooded surface of the LBB. The major flooding periods are related to the highest Relative Sea Level (RSL) (N−6 m) that occurred during interglacial periods, the highest sedimentation rates (10–30 cm/ka) and the finest sediment facies were found on the slope. During interglacial periods when RSL b −6 m, LBB was emerged but bank margins were still flooded and correspond to intermediate sedimentation rates (a few to 10 cm/ka) on the slope. Finally, during glacial periods (RSL b − 90 m), LBB was emerged (including its margins), sedimentation rates on the slope dropped to a few mm/ka associated to coarser sediment facies. Off-bank-transported sediment is the main sediment supply during sea-level highstands, occurring preferentially during three major periods of LBB flooding over the last 424 ka: marine isotopic stages 1, 5e and 11. During sea-level lowstands, shallow carbonate production was very low but could develop over a 4 km-wide plateau-like structure when RSL was above −40 m. The regional Antilles Current affected the sea floor along the northwestern LBB slope and influenced coral mound distribution as well as sediment facies and sequences along the upper and middle slopes (300–800 m). During glacial periods, the stronger influence of the Antilles Current upon the along-slope sedimentation promoted diagenesis via the development of indurated nodules in the upper slope (~400 m water depth). It also encouraged bi-gradational sequences showing a coarsening-up unit followed by a fining-up unit along the middle slope (~800 m water depth) that is thoroughly bioturbated. The characteristics of these contourite sequences were similar to those described in siliciclastic environments, but in contrast were condensed with low sedimentation rates over long (glacial) periods.
The Messinian is one of the strongest biogenic silica accumulation periods in the world and more ... more The Messinian is one of the strongest biogenic silica accumulation periods in the world and more particularly in the Mediterranean, where it is marked by an important diatomitic sedimentation. In the Boudinar basin (Morocco north-Eastern, Western Mediterranean), ...
Évolution des environnements littoraux du bassin de Melilla-Nador (Nord-Est Maroc) au Messinien s... more Évolution des environnements littoraux du bassin de Melilla-Nador (Nord-Est Maroc) au Messinien supérieur entre 6,0 et 5,77 Ma Evolution of Melilla-Nador basin (NE Morocco) littoral environments during late Messinian between 6.0 and 5.77 Ma Résumé L'étude de dépôts littoraux d'âge Messinien supérieur (ensemble E2 = « Terminal Carbonate Complex ») du Bassin de Melilla-Nador (Maroc) a permis de caractériser l'évolution des environnements entre 6,0 et 5,77 Ma environ, soit durant une période considérée comme contemporaine du début de la « crise de salinité messinienne ». L'étude et l'approche statistique de l'analyse pétrographique ont permis de préciser la dynamique sédimentaire des plates-formes et, en intégrant la géométrie observée des dépôts, de proposer des modèles reconstituant les milieux de dépôt. Les dépôts de l'ensemble E2 du bassin de Melilla-Nador se caractérisent par une évolution progressive, sans rupture majeure, des environnements littoraux en deux épisodes majeurs d'ouverture-comblement. Le premier correspond à l'édification d'un complexe récifal entre 6,0 et 5,85 Ma ; le second, entre 5,85 et 5,77 Ma, au développement d'une rampe oolitique mixte au cours du comblement progressif du bassin de Melilla-Nador. La comparaison avec le bassin de Sorbas (Espagne) montre une évolution très proche des environnements littoraux au Messinien supérieur, qui pourrait être utilisée comme outil de corrélation. Abstract This study of late Messinian deposits (E2 = TCC) from Melilla-Nador carbonate complex (Morocco) allowed us to characterize the environmental evolution between 6.0 and 5.77 Ma, which is a period considered as contemporaneous of the onset and development of the " messinian salinity crisis ". A statistical approach coupled together with classical petrographic study allows us to constrain the sedimentary dynamic of platforms and to propose deposition environment models. The Melilla-Nador platforms E2 deposits show a progressive continuous evolution of littoral environments in two major stages of available space creation and infill. The first stage corresponds to the build up of a reef complex between 6.0 and 5.85 Ma then the second stage, between 5.85 and 5.77 Ma, corresponds to the development of a mixed oolitic shallow ramp during the progressive infill of Melilla-Nador basin. The comparison with the Sorbas basin (Spain) TCC deposits exhibits a very close evolution of late Messinian littoral environments, which could be used as a correlation tool.
Le Messinien représente une des périodes de forte accumulation de silice biogénique dans le monde... more Le Messinien représente une des périodes de forte accumulation de silice biogénique dans le monde et plusparticulì erement en Méditerranée, o` u il est marqué par une importante sédimentation diatomitique. Dans le bassin de Boudinar (Maroc nord-oriental, Méditerranée occidentale), la coupe de Sidi Haj Youssef, localisée au pied du volcan de Ras Tarf, présente sur environ 100 m d'´ epaisseur une série argilo-marneuse dans laquelle s'intercalent douze niveaux diatomitiques de puissance variable. Effectuée pour lapremì ere fois en détail, l'´ etude microfloristique de diatomées, portant sur 86échantillons, a permis de reconnaˆıtre 50 genres de diatomées (24 des centriques et 26 des pennées) représentés par 185 espèces (75 espèces des centriques et 110 espèces des pennées). Pour chaqué echantillon un comptage de 400 individus a ´ eté effectué permettant de déterminer la fréquence relative de chaque taxon au sein de l'assemblage de diatomées. Ainsi, plusieurs assemblages ontété définis par la dominance des espèces suivantes : Coscinodiscus marginatus, Actinoptychus senarius, Thalassionema nitzschioides, Actinocyclus curvatulus, Thalassiothrix longissima, Rhizosolenia styliformis et Actinocyclus ehrenbergii. Ces assemblages témoignent d'un milieu marin littoral en communication avec la mer ouverte. L'abondance des espèces d'eaux froides vers la base et le sommet de la coupe traduit de largeséchanges du bassin avec l'océan atlantique au Messinien. La dominance des taxons comme Thalassionema nitzschioides et/ou Thalassiothrix longissima indique des périodes de forte productivité pouvantêtre reliée au fonctionnement d'upwellings. Abstract The Messinian is one of the strongest biogenic silica accumulation periods in the world and more particularly in the Mediterranean, where it is marked by an important diatomitic sedimentation. In the Boudinar basin (Morocco northEastern , Western Mediterranean), the section of Sidi Haj Youssef, localised near the volcano of Ras Tarf, has approximately 100 m thickness of clayey-marly series in which 12 diatomitic levels of variable thickness are intercalated. The microfloristic study of diatoms on 86 samples, carried out in detail for the first time, made it possible to recognize 50 genus of diatoms (24 of centric and 26 of pennate) represented by 185 species (75 species of centric and 110 species of pennate). Four hundred individuals were taken from each sample to determine the relative frequency of each taxon within the diatoms assemblages. Thus, several assemblages were defined by the predominance of the following species: Coscinodiscus marginatus, Actinoptychus senarius, Thalassionema nitzschioides, Actinocyclus curvatulus, Thalassiothrix longissima, Rhizosolenia styliformis and Actinocyclus ehrenbergii. These diatoms assemblages display a littoral marine environment in communication with the opened sea. The abundance of the cold water species towards the base and the top of the * Auteur correspondant.
... Paris Bierville, 1996)G. Bonaduce, D. Barra and G. Aiello, The areal and bathymetrical dist... more ... Paris Bierville, 1996)G. Bonaduce, D. Barra and G. Aiello, The areal and bathymetrical distribution of the genus Henryhowella Puri (Ostracoda) in ... J. Civis, J. De Porta and J. Martinell, Bioestratigrafia del Messiniense de la rambla de Arejos (Almeria), Abstracts of the papers ...
Egu General Assembly Conference Abstracts, May 1, 2014
The Bahamian Banks are a classic study area for carbonate sedimentation because it provides many ... more The Bahamian Banks are a classic study area for carbonate sedimentation because it provides many modern analogues for ancient limestones. Several sedimentary and seismic dataset collected during oceanographic research cruises (including ODP expeditions) have revealed significant accumulation rates along the slopes of the slopes of the Bahama Banks. In this work, we focus on the major sedimentary body of the northwestern slope of the Little Bahama Bank (LBB), the second largest carbonate bank of the Bahamian archipelago. Our main topic is a better understanding of the export processes from the bank to the northern slope of the LBB, exposed to the prevalent winds (windward side), and of the sediment deposition related to the regional Antilles Current. Analyses of two marine cores allow to determine the sediment sources (nature and origin of the particles) and to generate a high-resolution stratigraphic model. Those two cores (CARKS-20 and CARKS-21) are located along the western side of the northern slope of the LBB and have been collected during the CARAMBAR cruise (2010). CARKS-21 penetrates the wedge of this major sedimentary body over 12 m. CARKS-20 penetrates the same sedimentary body in its thickest part over 13.25 m. The stratigraphical methods include faunal and floral analyses (planktonic foraminifera and coccoliths), radiometric dating, XRF analyses and isotope stratigraphy. The sedimentary analyses encompass spectrophotocolorimetry and grain-size measurements, indurated thin sections petrographical study and identification of bioclasts. Stratigraphical results from core CARKS-21 allow to consider long-term climatic trends extending from present to the marine isotope stage (MIS) 11 (424 kyr, from the top to 9.3 m), and highlight perturbation in the sedimentation from 9.3 to 12 m (from MIS 12 to MIS 25). Higher resolutions are highlighted in core CARKS-20 which extends from MIS 1 to MIS 11. Glacial periods and sea-level lowstands corresponding to exposure of the bank are related to low production and exportation of sediment. These periods are characterized by reduced deposits showing a coarsening-up unit followed by a finning-up unit (bigradational sequences) and are associated with allochtonous particles constituted by phosphatized foraminiferal tests and pteropods shells. From MIS 1 to MIS 11, interglacial periods are well developed and exhibit higher sediment rates (e.g. ~ 5 cm/kyr in CARKS-20). Three clay-rich beds have been observed and the two most recent one are well dated and correspond to a part of MIS 7 and MIS 11 in both cores. The oldest bed (only found in core CARKS-21) is older than MIS 15. Off-bank processes are the major sedimentary processes during sea-level highstands, whereas current-related deposits dominate during sea-level lowstands in the northern Bahamas slope at least over the last 424 kyr. Clay-rich deposits may be related to a slowdown of currents, allowing clay-size particle settling on the contouritic system, and/or an increase of clay production and export from continental areas during a short period of MIS 7, MIS 11 and around MIS 15 - 25. Phosphatized particles result from a phase of early diagenesis concomitant with transport in the basin by the Antilles Current.
... d'Algérie et des régions méditerranéenne avoisinantes (Cita et al. 1968 ; Mazzola 19... more ... d'Algérie et des régions méditerranéenne avoisinantes (Cita et al. 1968 ; Mazzola 1971 ; Cita 1975 ; Iaccarino 1985 ; Hilgen et al. 2000b , 2003). CADRE GÉOGRAPHIQUE ET GÉOLOGIQUE Le Djebel Diss (Fig. 2) est situé à l'extrémité sud-occidentale des monts du Dahra, sur ...
Marine faunas have been recently found interbedded in the Messinian gypsum of Los Yesos, in the S... more Marine faunas have been recently found interbedded in the Messinian gypsum of Los Yesos, in the Sorbas Basin (SE Spain). More than 80 species have been identified, including molluscs, echinoids, foraminifers, ostracods, crustaceans and bryozoans. Several specimens from these exceptional marine fossils are figured for the first time. The palaeoecological analysis of these fossils show that their environment of deposit
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