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April 2012 - present
Publications
Publications (44)
Gas hydrates, a solid established by water and gas molecules, are widespread along the continental margins of the world. Their dynamics have mainly been regarded through the lens of temperature-pressure conditions. A fluctuation in one of these parameters may cause destabilization of gas hydrate-bearing sediments below the seafloor with implication...
How tectonic plates slip slowly and episodically along their boundaries, is a major, open question in earthquake science. Here, we use offshore in-situ sediment pore-pressure acquired in the proximity of the active offshore Main Marmara Fault and onshore geodetic time-series data set from a single GPS station to demonstrate the pore-pressure/deform...
Determining how gas hydrate distribution evolved along continental margins in the past is essential to understanding its evolution in the future. Moreover, hydrate decomposition has been linked to several catastrophic events, including some of the largest submarine landslides on Earth and the massive release of greenhouse gases into the ocean. Offs...
Submarine landslides constitute major marine and coastal geohazards, causing damage to marine infrastructures or even provoking tsunamis. For many authors, gas hydrate dissociation represents an effective triggering mechanism in generating sedimentary instabilities. In the Romanian upper slope of the Black Sea, failure headscarps are observed in an...
The role of solid Earth tide in fault reactivation has significant implications for understanding earthquake triggering, carbon sequestration, and the global carbon budget. Despite extensive research on this topic, the relationship between Earth tide and fault reactivation remains unclear. In this study, we investigate the influence of solid Earth...
On Earth, natural hydrates are mostly encountered in clay‐rich sediments. Yet their formation processes in such matrices remain poorly understood. Achieving an in‐depth understanding of how methane hydrates accumulate on continental margins is key to accurately assess (a) their role in sustaining the development of some chemosynthetic communities a...
The role of solid Earth tide in fault reactivation has significant implications for understanding earthquake triggering, carbon sequestration, and the global carbon budget. Despite extensive research on this topic over the years, the relationship between Earth tide and fault reactivation remains unclear. In this study, we investigate the potential...
Understanding and quantifying the hazards related to earthquake-induced submarine liquefaction and landslides are particularly significant offshore of tropical volcanic-carbonate islands, where carbonate production competes with volcanism to create highly contrasted lithological successions. To improve the detection of liquefaction-prone layers, we...
Seismic investigation in marine gas‐bearing sediments fails to get information below the acoustic mask created by free gas. To circumvent this problem, we combined collocated multichannel ultra‐high resolution seismic imaging, marine electrical resistivity tomography (MERT) and core sampling to study the physical properties of gas‐bearing sediments...
Pore water and sediment geochemistry in the western Black Sea were investigated on long Calypso piston core samples. Using this type of coring device facilitates the recovery of the thick sediment record necessary to analyze transport-reaction processes in response to the postglacial sea-level rise and intrusion of Mediterranean salt water 9 ka ago...
Plain Language Summary
Methane hydrate is an ice‐like compound composed of a cage of water molecules enclosing a methane molecule. Hydrates can form where water and methane are present under high pressure and low temperatures, for example, in deep‐sea sediments. As a result of climate change (e.g., seawater temperature increase), hydrates can melt...
Natural Gas Hydrates (NGH) collected during the Ghass cruise 2015 in the Western Black Sea onboard the R/V Pourquoi pas? are characterized by a suite of techniques. Gas Chromatography and Raman spectroscopy are used for the identification of the nature of the gas source, the hydrate structure and spatial variability of cage occupancies. The nature...
The evolution of submarine pockmarks is often related to the ascent of fluid from the subsurface. For pockmarks located within the gas hydrate stability zone, methane oversaturation can result in the formation of gas hydrates in the sediment. An ~600 m‐wide sea floor depression in deep waters offshore Nigeria, Pockmark A, was investigated for distr...
Offshore archives retrieved from marine/lacustrine environments receiving sediment from large river systems are valuable Quaternary continental records. In the present study, we reconstruct the Danube River activity at the end of the last glacial period based on sedimentological, mineralogical and geochemical analyses performed on long-piston cores...
Fluid migration within the sedimentary column contributes significantly to slope failure and pockmark formation and can be an effective triggering mechanism to generate submarine landslides. Pockmarks are thus commonly listed among geohazards. Contrary to these accepted notions, we propose here an alternative view of pockmarks with an example from...
The Sea of Marmara (SoM) is a marine portion of the North Anatolian Fault (NAF) and a portion of this fault that did not break during its 20th century earthquake sequence. The NAF in the SoM is characterized by both significant seismic activity and widespread fluid manifestations. These fluids have both shallow and deep origins in different parts o...
A comprehensive characterization of gas hydrate system offshore the western Black Sea was performed through an integrated analysis of geophysical data. We detected the bottom-simulating reflector (BSR), which marks, in this area, the base of gas hydrate stability. The observed BSR depth does not fit the theoretical steady state base of gas hydrate...
A detailed study, based on ocean-bottom seismometers (OBSs) recordings from two recording periods (3.5 months in 2011 and 2 months in 2014) and on a high-resolution, 3D velocity model, is presented here, which provides an alternative view of the microseismicity along the submerged section of the North Anatolian fault (NAF) within the western Sea of...
Understanding micro-seismicity is a critical question for earthquake hazard assessment. Since the devastating earthquakes of Izmit and Duzce in 1999, the seismicity along the submerged section of North Anatolian Fault within the Sea of Marmara (comprising the "Istanbul seismic gap") has been extensively studied in order to infer its mechanical beha...
Pockmarks are commonly associated with depth and a vertical stack of reflection anomalies like, for instance, changes in amplitude, and positive or negative relief. The formation of pockmarks has been explained by catastrophic eruptions of gas from over pressure shallow gas pockets by continuous fluid discharge associated with bottom currents creat...
The geotechnical properties of clay sediments were investigated using laboratory and in-situ measurements as part of the geohazard assessment in the Romanian sector of the Black Sea affected by landslides and seafloor deformation features. The sediments were characterized as predominantly high plastic silty clay of high compressibility, low undrain...
The Romanian sector of the Black Sea deserves attention because the Danube deep-sea fan is one of the largest sediment depositional systems worldwide and is considered the world's most isolated sea, the largest anoxic water body on the planet and a unique energy-rich sea. Due to the high sediment accumulation rate, presence of organic matter and an...
Sedimentary archives are used to infer past climate and environment thanks to their physical and chemical properties. Sampling methods (millimetric or centimetric) and routine analysis are time and material consuming. The use of some specific spectroscopic methods and data analysis, allow to develop and perform some robust methods capable of (i) fa...
Landsliding processes are relatively well-constrained on clastic sedimentary margins but remain poorly
documented along carbonate slope and guyots. The southern central Mozambique Channel, between
Mozambique and Madagascar, hosts several isolated carbonate platforms called the “Iles Eparses” and adjacent
seamounts, which developed in shallow-water...
In the aftermath of the devastating tsunami on the Japanese coast in 2011, a French multi-partnership project called TANDEM has been launched to assess the impact of tsunamis generated or propagated in the vicinity of French Channel and Atlantic coastlines. Tsunami are usually generated by earthquakes, but can also be triggered by submarine landsli...
The Niger Delta is one of the largest hydrocarbon basin offshore Africa and it is well known for the presence of active pockmarks on the seabed. During the Guineco-MeBo cruise in 2011, long cores were taken from a pockmark cluster in order to investigate the state of its current activity. Gas hydrates, oil and pore-water were sampled for geochemica...
A review of recent literature shows that two geomorphologically different types of pockmarks, contribute to gas seepage at the seafloor. Type-1 pockmarks are defined as seafloor craters associated to fluid seepage and are the most classical type referred to as "pockmarks" in the literature. In contrast, Type-2 pockmarks reveal a complex seafloor mo...
Gas seeping to the seafloor through structures such as pockmarks may contribute significantly to the enrichment of atmospheric greenhouse gases and global warming. Gas seeps in the Gulf of Lions, Western Mediterranean, are cyclical and pockmark “life” is governed both by sediment accumulation on the continental margin and Quaternary climate changes...
In previous works, it has been suggested that dissolution of gas hydrate can be responsible for pockmark formation and evolution in deepwater Nigeria. It was shown that those pockmarks which are at different stages of maturation are characterized by a common internal architecture associated to gas hydrate dynamics. New results obtained by drilling...
The Corsica Trough between the island of Corsica and the mainland of Italy is dominated on its western side by turbidite channel-lobe systems fed by high-gradient rivers during glacial epochs, while the eastern side is markedly different. It is flanked by the Pianosa Ridge, a prominent tectonic structure confining the distal reaches of turbidite lo...
A series of pockmarks observed at the seabed matches well the perimeter
of a large submarine landslide, called NG1, located on the outer shelf
and continental slope of the Eastern Gulf of Guinea. NG1 extends over
200 km2, is covered by a 120-m thick sedimentary layer which
tapers downslope, and has an internal structure clearly identified in 3D
sei...
A joint industrial project with IFREMER and Total provides insights into the tectonic setting and the geochemistry of a large active pockmark offshore W-Africa in the Niger Delta. The study combines both geophysical (seismic) and geochemical data to infer the dynamics of a 300 m wide pockmark located at 667 m water depth. Two Calypso cores, one at...
To characterize the link between faults and fluid release and to identify therole of fluid flow in gas hydrate occurrences, four piezometers were deployedat the border of a shale-cored anticline in the eastern Niger delta. Two ofthose piezometers were deployed along a major fault linked to a shallowhydrocarbon reservoir while the two others were de...
On seismic profiles, the Eastern Niger Submarine Delta displays spectacular prograding wedges separated by discontinuities on the continental shelf and correlative conformities seawards. In spite of the numerous studies focused on deep oil reservoirs in this area, and because of the presence of pronounced syndepositional deformation, the detailed g...
Gas hydrates were recovered by coring at the eastern border of a
shale-cored anticline in the eastern Niger Delta. To characterize the
link between faults and fluid release and to identify the role of fluid
flow in the gas hydrate dynamics, three piezometers were deployed for
periods ranging from 387 to 435 days. Two of them were deployed along a
m...
Morphological Signature of Fluid Flow Seepage in the Eastern Niger Submarine Delta (ENSD)
ABSTRACT
Pockmarks are crater-like depressions resulting from fluid flows at the seabed. Fluids may be of different types (water, gas, oil) and origins (dewatering, biogenic, thermogenic). In the Eastern Niger Submarine Delta (ENSD), pockmarks are generally c...
The circulation of methane-rich fluids at cold seeps often leads to precipitation of authigenic carbonates mediated by microbial activity, which can be used as archives of fluid seepage on continental margins. In this study, we have investigated the potential of using rare earth element (REE) concentrations in authigenic carbonates for tracing flui...
In a site investigation of the eastern part of the offshore Niger delta, cone penetration tests (CPTU) showed significant
drops in tip resistance, associated with decreases in sleeve friction and induced excess pore pressures at the interface between
superficial sediments and the underlying deposits of a mass-transport complex (MTC) called NG1. Suc...
One of the basic needs of deepwater oil exploration consists in the assessment of seafloor geohazards in areas of hydrocarbon exploration and production. The deployment of pipelines, anchors and subsea installations, for example, has an impact on the seafloor and demands an adaptation in the definition of geohazards. We show here an example of appl...
