Genetic Relations Between the Aves Ridge and the Grenada Back-Arc Basin, East Caribbean Sea

The Grenada Basin separates the active Lesser Antilles Arc from the Aves Ridge, described as a Cretaceous‐Paleocene remnant of the “Great Arc of the Caribbean.” Although various tectonic models have been proposed for the opening of the Grenada Basin, the data on which they rely are insufficient to reach definitive conclusions. This study presents, a large set of deep‐penetrating multichannel seismic reflection data and dredge samples acquired during the GARANTI cruise in 2017. By combining them with published data including seismic reflection data, wide‐angle seismic data, well data and dredges, we refine the understanding of the basement structure, depositional history, tectonic deformation and vertical motions of the Grenada Basin and its margins as follows: (1) rifting occurred during the late Paleocene‐early Eocene in a NW‐SE direction and led to seafloor spreading during the middle Eocene; (2) this newly formed oceanic crust now extends across the eastern Grenada Basin between the latitude of Grenada and Martinique; (3) asymmetrical pre‐Miocene depocenters support the hypothesis that the southern Grenada Basin originally extended beneath the present‐day southern Lesser Antilles Arc and probably partly into the present‐day forearc before the late Oligocene‐Miocene rise of the Lesser Antilles Arc; and (4) the Aves Ridge has subsided along with the Grenada Basin since at least the middle Eocene, with a general subsidence slowdown or even an uplift during the late Oligocene, and a sharp acceleration on its southeastern flank during the late Miocene. Until this acceleration of subsidence, several bathymetric highs remained shallow enough to develop carbonate platforms

Marine habitat classification: a pluridisciplinary approach in a high macrotidal environment - The case of the English median Channel

In megatidal sea, benthic marine communities are strongly dependent on the substrate, which is fashioned by hydrodynamism. This interdependence between substrate and benthic communities has enabled the establishment of marine benthic habitats classifications. Such classification allows depicting at the same time the general habitats diversity at the scale of a given shelf, and the local variations at the scale of a smaller area. Indeed, it meets diverse needs for ecological description of the marine environment such as general habitat knowledge or environmental impact assessment. The EUNIS classification is available to describe the main habitats of the European marine seabeds (Davies et al., 2004). Based on available data at the time of its delivery, it is well adapted to describe shallow bays and estuarine environments, mostly characterised by mobile muddy fine sediments. On the contrary it fails in describing correctly clean coarser sediments habitats in more deep areas such as those found in the central part of English Channel (La Manche) (Connor, 2005; James et al., 2007). This continental shelf sea connects with the Atlantic Ocean in its western part and to the Southern North Sea in its eastern part. It is characterised by a series of strong offshore-inshore and capes/bays gradients characterised by progressive changes in temperature, bathymetry, shear stress that are registered in the sediment, but also in the benthic communities

Water column distribution of zooplanktonic size classes derived from in-situ plankton profilers: Potential use to contextualize contaminant loads in plankton

Pollution is one of the main anthropogenic threats to marine ecosystems. Studies analysing the accumulation and transfer of contaminants in planktonic food webs tend to rely on samples collected in discrete water bodies. Here, we assessed the representativeness of measurements at the chlorophyll-a maximum layer during the MERITE-HIPPOCAMPE cruise for the entire water column by investigating the vertical distribution of particles and plankton obtained by in-situ optical profilers at nine stations across the Mediterranean Sea. We identified specific conditions where the interpretation of results from contaminant analyses can be improved by detailing plankton size structure and vertical distributions. First, the presence of higher than usual plankton concentrations can result in sampling issues that will affect biomass estimation within each size class and therefore bias our understanding of the contaminant dynamics. Secondly, the presence of an unsampled water layer with high zooplankton biomass might imply non-resolved contaminant pathways along the trophic structure. This study lays the basis for optimizing sampling strategy in contaminant studies

Benthic habitat diversity in coarse sediment under high macrotidal environment

EUNIS (European Nature Information System) is the habitat typology of reference in Europe but it must be implemented by new observations, particularly for the more detailed levels of the classification in coarse sediments which were historically less explored because of sampling difficulties. Two surveys in 2010 and 2011 permitted to sample twelve rectangular areas in the mid part of the Channel dominated by coarse sediment habitats in a high hydrodynamic environment strongly influenced by tidal currents (see Trentesaux et al., this conference for the map). During the survey, four longitudinal side-scan sonar (SSS) profiles were realised (~10 nm length) in each area allowing a real time selection of sampling areas. A minimum of four 0.25 m² Hamon grab sampling stations for quantitative macrofaunal and sediment analysis and two video footages (ROV Seabotix LBV200) were selected in each area (see figure). The main objectives of this study were to re-assess the EUNIS typology along an east-west gradient in the English Channel, and to find a way to integrate acoustic information in the description and mapping of the habitats which is not yet taken into account

Marine habitat classification: a pluridisciplinary approach in a high macrotidal environment - The case of the English median Channel

In megatidal sea, benthic marine communities are strongly dependent on the substrate, which is fashioned by hydrodynamism. This interdependence between substrate and benthic communities has enabled the establishment of marine benthic habitats classifications. Such classification allows depicting at the same time the general habitats diversity at the scale of a given shelf, and the local variations at the scale of a smaller area. Indeed, it meets diverse needs for ecological description of the marine environment such as general habitat knowledge or environmental impact assessment. The EUNIS classification is available to describe the main habitats of the European marine seabeds (Davies et al., 2004). Based on available data at the time of its delivery, it is well adapted to describe shallow bays and estuarine environments, mostly characterised by mobile muddy fine sediments. On the contrary it fails in describing correctly clean coarser sediments habitats in more deep areas such as those found in the central part of English Channel (La Manche) (Connor, 2005; James et al., 2007). This continental shelf sea connects with the Atlantic Ocean in its western part and to the Southern North Sea in its eastern part. It is characterised by a series of strong offshore-inshore and capes/bays gradients characterised by progressive changes in temperature, bathymetry, shear stress that are registered in the sediment, but also in the benthic communities

Benthic habitat diversity in coarse sediment under high macrotidal environment

EUNIS (European Nature Information System) is the habitat typology of reference in Europe but it must be implemented by new observations, particularly for the more detailed levels of the classification in coarse sediments which were historically less explored because of sampling difficulties. Two surveys in 2010 and 2011 permitted to sample twelve rectangular areas in the mid part of the Channel dominated by coarse sediment habitats in a high hydrodynamic environment strongly influenced by tidal currents (see Trentesaux et al., this conference for the map). During the survey, four longitudinal side-scan sonar (SSS) profiles were realised (~10 nm length) in each area allowing a real time selection of sampling areas. A minimum of four 0.25 m² Hamon grab sampling stations for quantitative macrofaunal and sediment analysis and two video footages (ROV Seabotix LBV200) were selected in each area (see figure). The main objectives of this study were to re-assess the EUNIS typology along an east-west gradient in the English Channel, and to find a way to integrate acoustic information in the description and mapping of the habitats which is not yet taken into account

Benthic habitat diversity in coarse sediment under high macrotidal environment

EUNIS (European Nature Information System) is the habitat typology of reference in Europe but it must be implemented by new observations, particularly for the more detailed levels of the classification in coarse sediments which were historically less explored because of sampling difficulties. Two surveys in 2010 and 2011 permitted to sample twelve rectangular areas in the mid part of the Channel dominated by coarse sediment habitats in a high hydrodynamic environment strongly influenced by tidal currents (see Trentesaux et al., this conference for the map). During the survey, four longitudinal side-scan sonar (SSS) profiles were realised (~10 nm length) in each area allowing a real time selection of sampling areas. A minimum of four 0.25 m² Hamon grab sampling stations for quantitative macrofaunal and sediment analysis and two video footages (ROV Seabotix LBV200) were selected in each area (see figure). The main objectives of this study were to re-assess the EUNIS typology along an east-west gradient in the English Channel, and to find a way to integrate acoustic information in the description and mapping of the habitats which is not yet taken into account

Marine habitat classification: a pluridisciplinary approach in a high macrotidal environment - The case of the English median Channel

In megatidal sea, benthic marine communities are strongly dependent on the substrate, which is fashioned by hydrodynamism. This interdependence between substrate and benthic communities has enabled the establishment of marine benthic habitats classifications. Such classification allows depicting at the same time the general habitats diversity at the scale of a given shelf, and the local variations at the scale of a smaller area. Indeed, it meets diverse needs for ecological description of the marine environment such as general habitat knowledge or environmental impact assessment. The EUNIS classification is available to describe the main habitats of the European marine seabeds (Davies et al., 2004). Based on available data at the time of its delivery, it is well adapted to describe shallow bays and estuarine environments, mostly characterised by mobile muddy fine sediments. On the contrary it fails in describing correctly clean coarser sediments habitats in more deep areas such as those found in the central part of English Channel (La Manche) (Connor, 2005; James et al., 2007). This continental shelf sea connects with the Atlantic Ocean in its western part and to the Southern North Sea in its eastern part. It is characterised by a series of strong offshore-inshore and capes/bays gradients characterised by progressive changes in temperature, bathymetry, shear stress that are registered in the sediment, but also in the benthic communities

Crustal and upper mantle 3-D Vs structure of the Pannonian region from joint earthquake and ambient noise Rayleigh wave tomography

SUMMARY The Pannonian Basin, situated in Central Europe, is surrounded by the Alpine, Carpathian and Dinaric orogens. To understand its tectonic characteristics and evolution, we determine a shear wave velocity model of its crust, mantle lithosphere and asthenosphere consistently by jointly inverting Rayleigh wave phase velocities measured consistently from earthquake (EQ) and ambient noise (AN) data. For the AN data, continuous waveform data were collected from 1254 stations, covering an area within 9° from the centre of the Pannonian Basin during the time period from 2006 to 2018. This data set enabled the extraction of over 164 464 interstation Rayleigh phase-velocity curves, after applying a strict quality control workflow. For the EQ data set more than 2000 seismic events and about 1350 seismic stations were used in the broader Central and Eastern European region between the time-span of 1990 to 2015, allowing us to extract 139 987 quality controlled Rayleigh wave phase-velocity curve. Using the combined data set, a small period- and distance-dependent bias between ambient noise and earthquake measurements, mostly below 1 per cent but becoming larger towards longer periods has been found. After applying a period and distance dependent correction, we generated phase-velocity maps, spanning periods from 5 to 250 s. 33 981 local dispersion curves were extracted and a new approach is introduced to link their period-dependent roughness to the standard deviation. Using a non-linear stochastic particle swarm optimization, a consistent 3-D shear wave velocity model (PanREA2023) encompassing the crust and upper mantle down to 300 km depth was obtained with a lateral resolution reaching about 50 km at the centre of the study area for shorter periods. The crust beneath the Carpathian orogen exhibits a distinct low-velocity anomaly extending down to the Moho. It is referred to as Peri-Carpathian anomaly. Similar anomalies were observed in the Northern Apennines, while the Eastern Alps and Dinarides, as collisional orogens, generally demonstrate higher velocities in the upper crust. High crustal shear wave velocities are also evident in the Bohemian Massif and the East European Craton. The brittle upper crust of the Pannonian Basin is characterized by alternating NE–SW trending high- and low-velocity anomalies: the western and central Pannonian low-velocity anomalies and the Transdanubian and Apuseni high-velocity anomalies related to Miocene sedimentary basins and intervening intervening interbasinal highs exposing Pre-Cenozoic rocks including crystalline basement rocks. Beneath the Southeastern Carpathians, a NE-dipping slab was identified, extending to depths of at least 200 km, while a slab gap is evident beneath the Western Carpathians. A short south-dipping Eurasian slab was imaged beneath the Eastern Alps down to only 150–200 km depth. The Adriatic lithosphere is subducting near-vertically dipping beneath the Northern Apennines, and a slab gap was observed beneath the Central Apennines. In the Northern Dinarides, a short slab was evident, reaching depths of around 150 km. The Southern Dinarides featured a thinned but possibly incompletely detached slab.</jats:p