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‘Cold’ seeps (or cold vents) are seafloor manifestations of fluid migration through sediments from the subsurface to the seabed and into the water column, and may reach the atmosphere. They are an important but not fully understood process in our oceans that has important repercussions on human society and on the climate. Modern sonar systems can obtain seafloor images of cold seep features from tens to thousands of meters wide with metric resolution, providing key information on the formation and evolution of the various seabed expressions of cold seeps. In this chapter we attempt to address cold seep systems with an emphasis on their origin, evolution, form, and occurrence, approaching them primarily from their morphologies and the acoustic character of the seafloor and near bottom erupted sediments. We address morphological characteristics of mud volcanoes, pockmarks, carbonate-related structures including MDAC, AOM and giant carbonate mounds and ridges, offering various examples mainly from recent discoveries in Mediterranean region which are among the most spectacular and most frequently cited examples. Detailed focus on topics such as acoustic backscatter, brine pools, etc. have been described in separate gray boxes of text with the aim to highlight their particular significance. Finally, gaps in knowledge and key research questions on cold seep studies have been outlined with the aim of orienting young researchers and students towards those topics that deserve the highest attention as they are still unresolved., Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Italia, FREMER Laboratoire Aléas géologiques et Dynamique Sédimentaire Centre Bretagne, Francia, Área de Geología Marina, Instituto Geológico y Minero de España, España, Lyngby Marine Geophysical Research, Países Bajos

A detailed multibeam survey and the subsequent gravity coring carried out in the Anaximander Mountains, Eastern Mediterranean, detected a new active gas hydrate-bearing mud volcano (MV) that was named Thessaloniki. It is outlined by the 1315 m bathymetric contour, is 1.67 km2 in area, and has a summit depth of 1260 m. The sea bottom water temperature is . The gas hydrate crystals generally have the form of flakes or rice, some larger aggregates of them are up to 2 cm across. A pressure core taken at the site contained 3.1 lt. of hydrocarbon gases composed of methane, nearly devoid of propane and butane. The sediment had a gas hydrate occupancy of 0.7% of the core volume. These characteristics place the gas hydrate field at Thessaloniki MV at the upper boundary of the gas hydrate stability zone, prone to dissociation with the slightest increase in sea water temperature, decrease in hydrostatic pressure, or change in the temperature of the advecting fluids.

Fluid escape structures on the Nile Deep Sea Fan were investigated during the MEDIFLUX MIMES expedition in 2004. Mud volcanoes, pockmarks and authigenic carbonate structures were surveyed for the first time with a high-resolution deep-towed 75 kHz sidescan sonar and a 2-8 kHz Chirp sediment echosounder. In combination with existing multibeam bathymetry and detailed seafloor in situ geological observations, these new data allowed detailed seep analyses. About 60 gas flares were detected acoustically in the water column from the sidescan sonar raw data at water depths from 770 to 1700 m. These gas flares coincide at the seabed with 1) the centres of the mud volcanoes where mud is also extruded, 2) the borders of the mud volcanoes where the emitted gases contribute to the precipitation of authigenic carbonates, and 3) to the edges of broad sheets of authigenic carbonates. Subsurface sediments are commonly disturbed by ascending fluids throughout the delta, with an abundance of seep-related carbonate structures on the seafloor. The feeder channels below mud volcanoes, similar to the gas conduits below the widespread carbonate crust structures and pockmarks, are relatively narrow and, for the vast majority of them, do not exceed a few metres in diameter. The seeps on the Nile Deep Sea Fan clearly follow lineations on the seafloor that we can relate to faults. (C) 2010 Elsevier B.V. All rights reserved.

Enigmatic seafloor gouge marks at depths of 1700-2100 m have been observed from submersible during geological survey work studying mud volcanoes in the eastern Mediterranean Sea. The marks consist of a central groove (about 10 cm deep and 1-2 m long), superimposed on a broader bowl-shaped depression (1-2 m long by about 50 cm wide) with raised rims (up to 10 cm high) to either side of the central groove. We discuss the potential biological causes of these marks, and conclude that they are probably created by Cuvier's beaked whales (Ziphius cavirostris) during foraging dives to these depths. The mud volcanoes have a comparatively rich and diverse benthic ecology associated with methane-rich fluid seeps and thus could be the base of food chains that reach top predators like the deep-diving whales. The characteristic high acoustic backscatter of the mud volcanoes would facilitate their detection by the echolocation system of these whales. © 2006 Elsevier Ltd. All rights reserved.

The Anaximander Mountains, occupying an outer-arc position at the junction of the Hellenic and Cyprus arcs, have been studied using a suite of geophysical data including multibeam swath bathymetry, backscatter images, seismic reflection profiles and gravity and magnetic data, which support an improved description of its deformation history. Lithologically, the western mountains can be correlated with the neritic limestones of the Bey Daǧlari unit of SW Turkey. The eastern mountains relate to the ophiolitic Antalya Nappe Complex. In addition to this lithological contrast, a deep-seated crustal difference, which is best reflected in gravimetry, relates to the mid-Tortonian Aksu thrust phase. After the Early-Middle Miocene eastward emplacement of the Lycian Nappes, the Serravallian-Tortonian stage was characterized by the development of an array of grabens with N120°E strikes, which occupied a vast continental area that extended from southern Aegean to southwestern Turkey. During the mid-Tortonian, the last phase of thrusting marked the onset of a different kinematic regime related to the westward rotation of the Anatolian platelet. This Late Miocene change marked the start of differential subsidence that resulted in the formation of the Anaximander Mountains and which is reflected by an unconformity surface between the Lower-Middle Miocene and Plio-Quaternary units. The Messinian-Quaternary period in the western part of the Anaximander Mountains was characterized by distributed sinistral shear parallel to N70°E, which was marked by the onset of an extension on N20°E-striking normal faults that formed long graben-like depressions. During the Pliocene, these basins were transected by N70°E-striking sinistral strike-slip fault zones, although continued crustal extension suggests deformation in transtension. The eastern part of the Anaximander Mountains is instead characterized by N150°E-striking normal and/or oblique normal fault zones, which lack significant evidence of strike-slip deformation. Close examination of newly calculated predicted relative plate motions between Africa (from NUVEL-1A) and Anatolia (from GPS measurements) indicates that plate motion vectors change rapidly at the junction between the Hellenic and Cyprus arcs because of the close proximity to the pole of Anatolian rotation. These calculations indicate that along both the eastern Hellenic Arc and the western Cyprus arcs (the Florence Rise), the relative motion between the Anatolian and African plates is sinistral. On the southern Florence Rise, deformation is characterized by pure left-lateral faulting, whereas farther northwest, in the eastern Anaximander Mountains, the component of strike-slip decreases. Although arc-normal convergence predicts the occurrence of thrust faulting, southwestward trench retreat also causes an extension internal to this outer-arc domain, such that the preexisting N120° E-striking thrust faults of the Aksu phase have been reactivated as normal to oblique normal faults during the Pliocene and Quaternary. The observed sinistral faulting on faults striking N70°E in the western mountains is consistent with the relative plate motion along the eastern Hellenic Arc and merges with the extensional domain in the eastern mountains. © 2004 Elsevier B.V. All rights reserved.

An anomalous strong, shallow reflector has been observed in several deep-tow subbottom profiler records in a region of the northern Black Sea characterised by seafloor fluid seeps, mud volcanoes, and the occurrence of gas hydrates. The digital data were processed using adapted seismic processing methods. Synthetic seismograms created to model representative traces from the observed profiles require anomalous alternations of acoustic properties in the upper sediments which can best be explained by interbedded layers of normal sediments and sediments with gas hydrates. The enigmatic strong reflector can be explained by constructive interference of reflections from five of these thin layers. It is proposed that the uppermost region of the gas hydrate stability zone here is represented by thinning layers of interbedded gas hydrates or layers with lower concentrations of gas hydrates.

A great number of circular to isometric depressions have been observed on the deep water seafloor in the eastern Mediterranean by MAK-1 and ORETech deep-tow side-scan sonar during several TTR cruises of the UNESCO Floating University Program since 1993, and also by visual observations made during the late 1998 French-Dutch MEDINAUT expedition. They extend from the Cobblestone mud volcano area in the west, passing all along the Mediterranean Ridge through the Olimpi and United Nation Rise mud volcano provinces to the Anaximander Mountains and Eratosthenes Seamount to the east. Several environments in which deep water pockmarks preferentially occur in the eastern Mediterranean are: (1) active mud volcanoes such as those of the Olimpi mud field and the Anaximander mountains; (2) remnant mud volcanoes and corresponding fault systems, like pockmarks on the flanks of buried volcanoes in the Cobblestone and United Nation Rise areas; (3) most abundantly on active faults like those on the Eratosthenes Seamount, Anaximander Mountains and on the Mediterranean Ridge; and (4) submarine slumps. Some pockmarks on the Mediterranean Ridge contain brines with high gas content. © 2002 Elsevier Science B.V. All rights reserved.

The offshore Anaximander Mountains are an important link between the Hellenic and Cyprus arcs. They were formed by southeastward rifting from Turkey in post-Miocene time. Gravity data have shown that the eastern part of the Anaximander Mountains is different from the western part; multibeam mapping seems to confirm that the eastern Anaximander Mountains have affinity with the Florence Rise structure (western Cyprus Arc). Faulting along and across the latter feature is characterized in the seismic data by anastomosing faults and pop-up flower structures. It is likely that progressive adjustment to incipient collision developed into a broad zone of NW–SE transpressive wrenching extending towards south Turkey. In contrast, the western mountains are more directly related to the opening of the Rhodes Basin and the Finike Basin, as transtension may have dominated in southwest Turkey since the Pliocene. The connection with onshore Turkey is still unclear, but could be related to the Fethiye–Burdur Fault Zone that defines the western boundary of the complex Isparta Angle. The Anaximander Mountains and the Isparta Angle form together a tectonic accommodation zone between the active deformation in southwestern Turkey and the Aegean region and the tectonically quieter Cyprus region. Copyright # 2003 John Wiley & Sons, Ltd.

Lucinoma kazani, a new deep-water species of Lucinidae from the Eastern Mediterranean Basin, is described and illustrated. The material was collected in the Anaximander Mountains, between Rhodes and Cyprus, Eastern Mediterranean. The first living specimens were collected during the Dutch ANAXIPROBE project in the Kazan volcano, at a depth of 1709 m. Later, during the MEDINAUT programme, both living specimens and shells were collected from several mud volcanoes at different depths in the Anaximander Mountains. This bivalve holds symbionts in the ctenidia, as do all previously studied Lucinidae. The type of habitat of this new species is gas-saturated mud, with high levels of methane, which diffuses upwards into a low-oxygen deep-water. Therefore, we consider this as evidence of a living cold seep community in the Eastern Mediterranean Sea. © 2002 Published by Elsevier Science Ltd.

The Menes caldera is a fault-controlled depression (~8 km in diameter) at ~3,000 m water depth in the western province of the Nile deep-sea fan off NW Egypt, comprising seven mud volcanoes (MVs) of which two are active. Based on multichannel and chirp seismic data, temperature profiles, and high-resolution bathymetric data collected during the 2000 Fanil, 2004 Mimes and 2007 Medeco2 expeditions, the present study investigates factors controlling MV morphology, the geometry of feeder channels, and the origin of emitted fluids. The active Cheops and Chephren MVs are 1,500 m wide with subcircular craters at their summits, about 250 m in diameter, generally a few tens of metres deep, and filled with methane-rich muddy brines with temperatures reaching 42 °C and 57 °C respectively. Deployments of CTDs and corers with attached temperature sensors tracked these warm temperatures down to almost 0.5 km depth below the brine lake surface at the Cheops MV, in a feeder channel probably only a few tens of metres wide. Thermogenic processes involve the dissolution of Messinian evaporites by warm fluids likely sourced even deeper, i.e. 1.7 and 2.6 km below the seabed at the Cheops and Chephren MVs respectively, and which ascend along listric faults. Seepage activity appears broadly persistent since the initiation of mud volcanism in the Early Pliocene, possibly accompanied by lateral migration of feeder channels.

Recent swath mapping and seismic reflection profiling across the eastern(Levantine) branch of the Mediterranean Ridge (MR), in the eastern Mediterranean Sea, illustrate a strong variability of the deformational styles that characterize this precollisional accretionary prism. Along a north-south cross-section of the MR, a structural analysis, based on surface mapping, combined with vertical seismic reflection data, reveals two main structural domains. A southern Outer Domain consists of a series of three disconnected distinct fold belts. Folding affects a sedimentary cover which includes an approximately 2-km thick Pliocene and Quaternary wedge in this domain, resting on fairly thick Messinian evaporitic sequences that act as probable decollement layers. The MR Inner Domain includes three regions showing evidences of strong internal deformations and of numerous probable mud cones and mud flows, but no seismic evidence of significant underlying Messinian evaporites can be detected. The inner sub-regions are thrusting northwards over an area made of faulted, and locally uplifted, acoustic basement blocks that constitute the southernmost extension of the Crete continental margin, acting as a continental buttress for the MR. This innermost domain is itself structurally disconnected from the Crete continental margin by the en echelon Pliny troughs system that shows evidence of left lateral displacement. Altogether, the different structural and sedimentary cover patterns reveal a strong contrast between both MR Inner and Outer Domains, and important lateral variations within the Inner MR itself. Strike-slip faulting seams to characterizes both areas, and large-scale mud accumulations potentially exist in the northern one. Our results support a model of imbricated accretionary prisms, including, at least, two stages: (1) a pre-Messinian stage during which the Inner MR probably developed in response to northward subduction of the African lithosphere beneath southern Europe, and (2) a Messinian to post-Messinian period, during which the kinematics of the Aegean-Anatolian microplates and the presence of thick Messinian deposits became prevalent and which led to the creation of the Outer MR folded wedge piling against the previous one. In our interpretation, the occurrence of thick Messinian evaporites in this area induces important local and regional modifications of the structural pattern. Strike-slip activities reflect partitioning related to oblique subduction, and likely lateral escape of the sedimentary cover in the whole studied area. ©2001 Elsevier Science B.V. All rights reserved.

New light is shed on the enigmatic Rhodes deep marine basin by a set of underway geophysical data across it, including swath bathymetry, seismic reflection profiles, gravity and magnetic data. This deep trough (as much as 4485 m) to the east of the Island of Rhodes and close to southwestern Turkey, contains no Messinian evaporites and only a thin Pliocene-Quaternary sedimentary section (< 1000 m) overlying an acoustic basement. This basement is likely composed of pre-Miocene tectonized rocks tentatively related to neighbouring Hellenide-Tauride alpine orogens. Reverse faulting, strike-slip faults, sedimentary nappes and mass sliding are presently occurring in the Rhodes Basin mainly around its edges. This tectonic activity, together with a relatively important seismicity (particularly along its northwestern margin), indicates that the basin is still evolving. We suggest that the Rhodes Basin results from a general collapse of what is now its brittle basement, in connection with the progressive development of transform motion along the eastern branch of the Hellenic Arc. If our hypotheses are correct, the Rhodes Basin is a relatively recent (post-Miocene) foundered trough, somewhat similar to pull-apart basins which have also developed along the transpressive branch of the Hellenic subduction zone, particularly along the Pliny Trench. (C) 2000 Elsevier Science B.V.

International audience; The Florence Ridge, part of the western Cyprus arc, is a compressional relief that was eroded during the Messinian salinity crisis while deposition of salt occurred North (Antalya basin) and South (Herodotus abyssal plain). In order to better assess the impact of salt-tectonics in the Florence Ridge region deformations, we conducted a morpho-structural analysis of available multibeam and seismic data (Simed and Prismed II campaigns). It is indeed a crucial issue to distinguish crustal and gravity driven structures in the compressional to strike-slip belts of the eastern Mediterranean.Along the Antalya basin, we mainly observed multi-directional tectonic rafts typical of gravity gliding above salt. On the Florence Ridge itself, the base of salt evolves laterally to a Messinian erosional surface that erodes a series of stacked nappes. This surface is involved in recent faulting. South of the Florence Ridge, a nearly 100 km wide fold belt characterizes the Herodotus abyssal plain. Three different zones parallel to the Florence Ridge appear within this fold belt. Those are respectively from North to South zones A, B and C. Zone A is characterized mainly by small-wavelength folding and faulting. Approaching Zone B, a long extensional graben deforms the seafloor. Zone B stands ~ 100 to 200 m higher than zones A and C. There, salt welding seems common. In the easternmost zone B deep sub-circular bathymetric depressions are associated with extremely thick and fan-shaped depocenters probably emplaced in relation with active sub-salt thrusts. Many evidences suggest post-Messinian uplift in this zone. Zone C shows medium to high wavelength salt-cored folds. Wavelength of those folds increase approaching the distal Nile deep-sea fan. Within zone C, a nearly undeformed domain exists approaching the Eratosthenes seamount. ‘En echelon’ folds bound this flat domain suggesting lateral salt extrusion at the junction between zone C and the distal Nile deep-sea fan.To conclude, numerous evidences argue for a post-Messinian reactivation of the pre-Messinian Florence Ridge accretionary wedge (numerous folds, uplifted zones). The salt, as on the nearby Mediterranean Ridge, decouples deep and surface deformations and even allow the development of isolated grabens and associated salt ridges in the heart of the Florence compressional zone. We propose in this case that local basal slope of salt increase related to basement fault activity triggered gravity gliding and thus extensional deformation despite the regional compressional regime. Finally, this study shows that the eastern Nile deep-sea fan, submitted to extremely vigorous salt tectonics seems to have collided with the Florence Ridge fold belt and to have generated a “salt extrusion” zone.

A survey of a large field of mud diapirs on the Mediterranean Ridge south of Crete was carried out using both OKEAN (9.5 kHz) and MAK-1M (30 kHz) sidescan sonar systems during Leg-2 of the Third Training Through Research cruise of R/V Gelendzhik in June and July, 1993. High backscatter intensities were recorded by both systems to different degrees over the mud diapirs and their immediate surroundings. Causes of variations in the backscatter intensity are considered to be the spatial distribution of mud breccia associated with the mud domes (both the burial depth of the mud breccia beneath hemipelagic drape and its areal extent) and its physical properties, along with contributions from seafloor roughness and the topography of the mud domes. Significant sources of volume scattering of the sidescan sonar sound signal are considered to be mud breccia inhomogeneities represented by millimetric/centimetric clasts of various lithologies and free gas bubbles distributed through the mud matrix. A good general relationship is established between these sources and the observed backscatter variations through analysis of ground truth data from core samples, with 5 kHz deep-tow subbottom profiler records and seafloor video observations as well as the sidescan sonar records; but a fully quantitative assessment of this relationship would require acoustic modelling and additional ground truth data.

The Mediterranean Ridge, stretching from the Calabrian Rise to the Florence Rise, is the largest structural unit of the Eastern Mediterranean Sea. It is directly related to ongoing convergence and collision of the African and Eurasian plates, starting in the Oligocene, and is considered to be a giant accretionary complex consisting of intensively folded and faulted rocks of the African margin. Since its origin in the late Miocene, the Ridge continued to grow up and outward, experiencing more deformation because of the developing collision. The mud diapirism and mud volcanism are usual and wide-spread phenomena for the Mediterranean Ridge that developed as a result of an intensive tectonic overburden due to stacking of rock units by thrusting and strong lateral compressional stress pressing up and squeezing plastic sedimentary series out onto the seafloor.

New information on the geometry of the mud volcanoes, folds and faults located in the central part of the Mediterranean Ridge is provided from long range and deep-tow sidescan sonar images, high resolution seismic and low frequency echosounder profiles, and gravity cores obtained on the R/V Gelendzhik during the 1993 UNESCO-ESF Training Through Research cruise. Symmetrical gentle folds, with a mean wavelength of 750 m, deform predominantly Pliocene-Quaternary sediments, but also perhaps as old as Messinian. In most areas of the Mediterranean Ridge, the north-northeast directed subduction of the African plate below the Eurasian plate at the Hellenic arc produces folds with hinge lines subparallel to the trend of the ridge. However, the hinge lines of the folds curve around the southern part of the area with highest concentration of mud volcanoes and produce an irregular U-shape fold belt. Some of the folds show an intrusive nucleus and, in some of them, mud breccia appears to have flowed from the flanks of the folds into the troughs. The mud volcanoes consist of domes of interlayered pelagic sediments and mud breccias containing sediments and rock fragments of Late Aptian to Pleistocene ages. Mud breccia flows are mainly extruded radially from vents, although rare fissure extrusions are also observed. The mud volcanoes have an irregular to elliptical shape, with diameters up to 16 km. The distribution of mud volcanoes in the area is irregular, but they are more frequent in an area called the Olimpi Field. Faults in the uppermost part of the Mediterranean Ridge are rare. Most of the faults are normal and subparallel to fold limbs. In addition, N20°E and N100°E subvertical faults are found controlling the shape of the mud volcanoes.

MAK-1M deep tow sidescan sonar surveys have revealed two echo-free patches in an area of mud diapirs on the Mediterranean Ridge. The unusual shape of these patches and absence of returned signal can be explained more easily by the presence of brine pools rather than as a topography effect. The high acoustic impedance contrast at the interface between brine and seawater, a result of the salinity contrast there causing a relatively high contrast in sound velocity and water density, acts as a screen preventing sidescan sonar sound signal at low grazing angles from reaching the seafloor. Sound is reflected and refracted away from the sonar towfish without any backscatter. The inferred brine pools appear to be associated with faults recognized on sonographs and subbottom profiler records. This first observation of brine pools related to mud volcanoes and mud diapirs suggests that salt is present in areas of mud diapirism, possibly playing a role in that process, or at least that the brines and mud may share flow paths within the Mediterranean Ridge.

Direct observation of active emission of fluids and mud from a submarine mud volcano were made for the first time in an extensive field of mud diapirs and mud volcanoes on the Mediterranean Ridge using a video camera towed 2 m above the seafloor in 1800 m of water. This recent research using both long range and deep-towed sidescan sonar systems indicates also that diapirism and eruption of mud along the crest of the ridge is more common than previously thought. The southwards increase in age of rock fragments carried within the erupted mud supports the hypothesis that the fluid mud becomes overpressured within a southward-dipping backthrust from the Inner Deformation Front of this accretionary prism.

Important new light is shed on subduction and incipient collisional processes in the Easternmost Mediterranean, notably the Plio-Quaternary uplift of the Troodos ophiolite, from new geophysical information collected during a cruise of the R.V. Gelendzhik in July 1993, as part of the Training-through-Research' programme. The data collected over the Eratosthenes Seamount formed part of the site-survey work for Leg 160 of the Ocean Drilling Program scheduled for spring 1995. The main results are that the Eratosthenes Seamount is in the process of actively subsiding, breaking-up and being thrust, beneath both Cyprus to the north and the Levantine Basin to the south. Northwards thrusting appears to post-date the Messinian, when evaporites accumulated around the lower flanks of a pre-existing seamount feature. Comparison with the geology of southern Cyprus and offshore areas suggests a causative link between northward underthrusting of the Eratosthenes Seamount and late Pliocene-mid Quaternary uplift of southern Cyprus, focused on the centre of the Troodos ophiolite.

The geometry and nature of the eastern segment of the Cyprean Arc are little understood. Several hypotheses have been put forward to explain the tectonic situation there. Recent marine geophysical data for this region mapped several deep and shallow structural elements. The most prominent element is a ridge, the Latakia Ridge, which extends from the Syrian coast near Latakia south-westward, to meet with an east-west trending bathymetric escarpment east of the Hecateus Ridge. The new seismic profiles suggest that these two elements mark the present plate boundary along the eastern Cyprean Arc. The Latakia Ridge is a young and still active feature. It was formed by southward migration of the plate boundary. The ridge probably originated as a large thrust sheet, which later, when the convergence direction was changed, became a zone of wrench faulting. The ridge is still forming today and serves as a dam to the sediments north of it. The wrench faulting activity is more pronounced in the eastern segment of the ridge.

A very successful scientific exploration carried out on the crestal area of the Mediterranean Ridge (MR) south of Crete, where the accretionary prism is in a collisional context, lead to the discovery of at least 17 new mud diapirs. They were surveyed by the R/VGelendzhik with the side-scan imageries, the largest covering an area of up to 100 km2. The age of the extruded mud breccia increases as a function of the distance from the Inner Deformation Front of the MR. Violent fluid venting was first docu-mented in a non-hydrothermal context.

We report on a multidisciplinary study of cold seeps explored in the Central Nile deep-sea fan of the Egyptian margin. Our approach combines in situ seafloor observation, geophysics, sedimentological data, measurement of bottom-water methane anomalies, pore-water and sediment geochemistry, and Th-230/U dating of authigenic carbonates. Two areas were investigated, which correspond to different sedimentary provinces. The lower slope, at similar to 2100 m water depth, indicates deformation of sediments by gravitational processes, exhibiting slope-parallel elongated ridges and seafloor depressions. In contrast, the middle slope, at similar to 1650 m water depth, exhibits a series of debris-flow deposits not remobilized by post-depositional gravity processes. Significant differences exist between fluid-escape structures from the two studied areas. At the lower slope, methane anomalies were detected in bottom-waters above the depressions, whereas the adjacent ridges show a frequent coverage of fractured carbonate pavements associated with chemosynthetic vent communities. Carbonate U/Th age dates (similar to 8 kyr BP), pore-water sulphate and solid phase sediment data suggest that seepage activity at those carbonate ridges has decreased over the recent past. In contrast, large (similar to 1 km(2)) carbonate-paved areas were discovered in the middle slope, with U/Th isotope evidence for ongoing carbonate precipitation during the Late Holocene (since similar to 5 kyr BP at least). Our results suggest that fluid venting is closely related to sediment deformation in the Central Nile margin. It is proposed that slope instability leads to focused fluid flow in the lower slope and exposure of 'fossil' carbonate ridges, whereas pervasive diffuse flow prevails at the unfailed middle slope.

Lykousis, V. ... et al.-- 19 pages, 19 figures, Detailed multibeam, sedimentological, and geophysical surveys provide ample new data to confirm that the Anaximander Mountains (Eastern Mediterranean) are an important area for active mud volcanism and gas hydrate formation. More than 3000 km of multibeam track length was acquired during two recent missions and 80 gravity and box cores were recovered. Morphology and backscatter data of the study area have better resolution than previous surveys, and very detailed morphology maps have been made of the known targeted mud volcanoes (Amsterdam, Kazan and Kula), especially the Amsterdam "crater" and the related mud breccia flows. Gas hydrates collected repeatedly from a large area of Amsterdam mud volcano at a sub-bottom depth of around 0.3-1.5 m resemble compacted snow and have a rather flaky form. New gas hydrate sites were found at Amsterdam mud volcano, including the mud flow sloping off to the south. Gas hydrates sampled for the first time at Kazan mud volcano are dispersed throughout the core samples deeper than 0.3 m and display a 'rice'-like appearance. Relative chronology and AMS dating of interbedded pelagic sediments (Late Holocene hemipelagic, sapropel layer S1 and ash layers) within the mud flows indicate that successive eruptions of Kula mud volcano have a periodicity of about 5-10 kyrs. New mud volcanoes identified on the basis of multibeam backscatter intensity were sampled, documented as active and named "Athina" and "Thessaloniki". Gas hydrates were sampled also in Thessaloniki mud volcano, the shallowest (1264 m) among all the active Mediterranean sites, at the boundary of the gas hydrate stability zone. Biostratigraphical analyses of mud breccia clasts indicated that the source of the subsurface sedimentary sequences consists of Late Cretaceous limestones, Paleocene siliciclastic rocks, Eocene biogenic limestones and Miocene mudstones. Rough estimations of the total capacity of the Anaximander mud volcanoes in methane gas are 2.56-6.40 km3. © 2008 Elsevier Ltd. All rights reserved, This work is a part of the EC ANAXIMANDER project (EVK-CT-2002-00068). The European Commission is acknowledged for their financial contribution to the projec

Marine Geology, v. 261, n. 1-4, p. 138-152, 2009. http://dx.doi.org/10.1016/j.margeo.2009.02.005; International audience; This paper reports the first "in situ" seafloor observations of fluid escape structures in a fault-controlled caldera-type depression of about 8 km diameter, named the Menes caldera, in the Eastern Mediterranean sea off Egypt (western province of the Nile Deep Sea Fan). A detailed analysis of seven Nautile dives, performed during the Nautinil cruise in 2003, focused on determining the nature, origin, importance, mechanisms and environmental impacts of the fluid escape processes from the geological observations. Seafloor maps, constructed from direct visual observations and video records made from the submersible, and sampling results, for three mud volcanoes of the caldera, Cheops, Chephren and Mykerinos show differences in activity but many common characteristics. The three volcanoes show a crater-like depression. The study reveals a strong contrast between Mykerinos, where no seepage activity was found, and the craters of Cheops and Chephren, where an intense activity of brine seepage was discovered. On Cheops, a dome of dark grey mud raises slightly above the brine surface in the central part of the brine lake, and shows numerous circular vents of 1-2 m diameter that become gradually colonized by microbial mats. Chephren hosts a deep (> 200 m) and warm (45 °C) brine lake. Alternations of areas void of or covered with microbial mats at the surface of the Chephren brine lake indicate large surface disturbances that may result from the occurrence of several active vents at the bottom of the lake. A special feature at Chephren is a brine overflow at the western edge of the crater, also indicative of the very high activity of brine seepage. The Nautinil observations indicate that the Menes caldera in the Eastern Mediterranean is a highly active site of brine seepage. Growth faults rooted in pre-Messinian sediment layers provide pathways for warm fluids to escape pressurized source levels below the Messinian salt.

As the total cost of healthcare continues to rise, computerized methods are sought to improve the overall efficiency and effectiveness of healthcare systems. In this application, the focus is on healthcare claim payment processing, which is a major component of administrative healthcare costs. Due to the complexity of healthcare data, current methods require a large amount of healthcare claim payment processing to occur through manual intervention by human operators. This limitation necessitates the inclusion of machine learning techniques to create a hybrid system for automation of healthcare claim payments. Further automation of claims payment processing will lead to improved quality cost components of healthcare delivery. Machine learning techniques are used to demonstrate the feasibility of a hybrid system for healthcare claim payment automation, leading to reduced administrative costs and increased efficiencies. When the administrative cost savings are applied to the industry, this contributes to lowering the overall cost of healthcare.

Four mud volcanoes of several kilometres diameter named Amon, Osiris, Isis, and North Alex and located above gas chimneys on the Central Nile Deep Sea Fan, were investigated for the first time with the submersible Nautile. One of the objectives was to characterize the seafloor morphology and the seepage activity across the mud volcanoes. The seepage activity was dominated by emissions of methane and heavier hydrocarbons associated with a major thermal contribution. The most active parts of the mud volcanoes were highly gas-saturated (methane concentrations in the water and in the sediments, respectively, of several hundreds of nmol/L and several mmol/L of wet sediment) and associated with significantly high thermal gradients (at 10 m below the seafloor, the recorded temperatures reached more than 40 °C). Patches of highly reduced blackish sediments, mats of sulphide-oxidizing bacteria, and precipitates of authigenic carbonate were detected, indicative of anaerobic methane consumption. The chemosynthetic fauna was, however, not very abundant, inhibited most likely by the high and vigorous fluxes, and was associated mainly with carbonate-crust-covered seafloor encountered on the southwestern flank of Amon. Mud expulsions are not very common at present and were found limited to the most active emission centres of two mud volcanoes, where slow extrusion of mud occurs. Each of the mud volcanoes is fed principally by a main narrow channel located below the most elevated areas, most commonly in the centres of the structures. The distribution, shape, and seafloor morphology of the mud volcanoes and associated seeps over the Central Nile Deep Sea Fan are clearly tectonically controlled.

The basins in the Eastern Mediterranean can be divided into those that were formed mainly in post-Miocene time and those that were formed during the rifting episodes that led to the formation of the Neotethys. The younger basins can be further divided into those that were formed mainly in post-Miocene time and those that were formed in post-Pliocene time. The separation is not only one of convenience but also corresponds to major adjustments in the plate tectonic situation in the Eastern Mediterranean. The late Miocene deposition of thick evaporites throughout the Mediterranean region, or, where evaporites are missing, the creation of an important erosional unconformity during the extreme lowstand of the Mediterranean, makes the Miocene-Pliocene boundary relatively easy to identify, especially on seismic reflection records. At about the same time, following the collision of the Arabian plate with Eurasia, the Anatolian and Aegean microplates came into existence between the convergent African and Eurasian plates to accommodate tectonic escape between them. The general configuration of the Eastern Mediterranean basins reflects the tectonic and structural gradients between the collisional domain of southeastern Turkey and Iran, and the continuing but increasingly limited subduction along the Calabrian and Hellenic arcs, with the Cyprus and Levantine zones between them. Several distinct zones can be identified in the Eastern Mediterranean. The Dead Sea Fault system marks the edge between the collisional and pre-collisional zones to the east and west, respectively. The meridian through the Anaximander Mountains (30©E) forms a rough boundary between the zone of incipient collision to the east and the zone of continuing but late-stage subduction to the west. The Malta Escarpment forms the Eastern boundary of the Eastern Mediterranean basins. The series of basins along the northern margin of the Eastern Mediterranean and the Aegean Sea share this progressive evolution, with those containing Messinian evaporites to the east and those without to the west. The Sicily Channel with its associated basins is an extensional zone between the Eastern and Western Mediterranean. The basins discussed in this paper are divided into two groups, the larger and older basins and the smaller and younger basins. In the first group are the Ionian Basin and the Levantine Basin, and in the second group the Cilicia Basin, Antalya Basin, Finike Basin, Rhodes Basin, Aegean basins, Sicily Channel basins, Latakia Basin and Larnaca Basin. The Eastern Mediterranean represents the last stage in the evolution of an ocean basin. Given the current motion between Africa and Eurasia, the Eastern Mediterranean will cease to exist in about 6-8 Ma from now. As a result, the larger and older basins are shrinking, whereas the younger and smaller basins are growing. Eventually the smaller basins will also disappear.

The first high-resolution mapping of mud volcanoes and mud domes of the Central Mediterranean Ridge (Eastern Mediterranean) presented here is based on successive in situ observations from the Nautile submersible [MEDINAUT (1998) and NAUTINIL (2003) surveys] and near-bottom side-scan sonar data (MEDINETH cruise, 1999). Data were obtained over two types of clay-kinetic-related features previously identified south of Crete: the Olimpi field mud volcanoes and the Southern belt mud domes, characterized by highly contrasting morpho-acoustic characteristics. Using the new data we can better define the morphological and backscatter characteristics of both mud volcanoes and mud domes and illustrate their similarities and differences; and establish ground truth, in terms of the presence or not of mud flows, diagenetic carbonate pavements, active seepage and macro-and microbiology. This study reveals strong contrasts between: (1) large mud volcanoes, made of successive mud flows, and associated with diagenetic carbonates and fluid venting activity, and (2) smaller mud domes, characterized by steep slopes affected by sedimentary instabilities, and without any evidence of mud flow, specific fluid seepage activity, authigenic carbonate pavement, or biologic communities. From these results we demonstrate a strong variability of clay-kinetic structures from the central domain of the Mediterranean Ridge accretionary complex to its northern thrust boundary against the Cretan continental backstop. From an integration of the high-resolution results to the Mediterranean Ridge geologic and structural settings, a qualitative model is finally proposed to explain the mud volcano and mud dome emplacement. © 2005 Elsevier Ltd. All rights reserved.

Submersible observations and seafloor mapping over areas of mud volcanism in the eastern Mediterranean Sea reveal an abundance of methane-rich fluid emissions, as well as specific seep-associated fauna (e.g. tubeworms, bivalves and chemosynthetic bacteria) and diagenetic deposits (i.e. carbonates crusts). Cold seeps characterized by abundant chemosynthetic bivalves, bacterial mats, and reduced sediments are the surface manifestations of present-day expulsion of methane-rich fluids, whereas massive carbonate crusts with clusters of tubeworms indicate long-term seeping that might be dormant at present. The surface characteristics of the mud flows (roughness of the surface, gas escape features, presence of hemipelagic dust, colonization by benthic fauna, development of carbonate crusts) present a high variability related to the intensity and age of seepage, and can be correlated to the observed backscatter variations. The repartition of the mud flows and active seeps is organized concentrically around the centre of the mud volcanoes and potential parasitic cones. Sidescan sonar backscatter patterns are thus indirectly related to spatial and temporal variation of mud volcanic activity. © 2004 Elsevier Ltd. All rights reserved.

Marine Geology, v. 209, n. 1-4, p. 245-263, 2004. http://dx.doi.org/10.1016/j.margeo.2004.05.002; International audience; Based on a recent marine geophysical data set, including swath bathymetry, acoustic imagery and six-channel seismics, recorded over a large area of the Mediterranean Ridge (MR) in early 1998 during the Prismed 2 survey, this paper presents a study of the various relationships observed between tectonic features cutting across the Central Mediterranean Ridge accretionary wedge and massive mud expulsions (known as mud volcanoes), identified over large areas of the ridge.Regional mapping of two of the mud volcano fields previously only partly investigated (Olimpi and United Nations Rise) revealed the presence of many new mud expulsion centres and a third new mud volcano field has been identified. All the mud features show great variability in morphology, size and backscatter strength of their surrounding mud flows. Based on their contrasting morpho-acoustic characteristics, we propose a classification into three main groups of mud construction: (1) “mud volcanoes”, these consist of subcircular and prominent reliefs, often associated with high backscatter mud flows; (2) “mud domes”, similar to mud volcano, but smaller, these occurrences correspond to weakly reflective mud constructions; (3) “mud plateaus” represent a third category which appears as wide, often highly reflective and rather flat mud extrusions. From all available data, an attempt to explain the different mud ascent processes and driving forces is discussed, in relation to the initial collision structural setting of the Central Mediterranean Ridge. Within this area, most of the mud constructions have been observed to be associated with tectonic features and, in particular, with strike-slip faulting for the first time. As a hypothesis, we propose in this paper two different ascent processes to explain the contrasting mud constructions: (1) “extrusion” for the mud volcanoes and plateaus and (2) “intrusion” for the mud domes, connected to two different mud levels controlled by the crustal geometry of this pre-collision area and especially the southwards extension of the Cretan continental crust below the Mediterranean Ridge accreted sediments.

Two mud volcano fields were explored during the French–Dutch MEDINAUT cruise (1998) with the submersible NAUTILE, one south of Crete along the Mediteranean Ridge at about 2000 m depth (Olimpi mud field) and the other south of Turkey between 1700 and 2000 m depth (Anaximander mud field) where high methane concentrations were measured. Chemosynthetic communities were observed and sampled on six mud volcanoes and along a fault scarp. The communities were dominated by bivalves of particularly small size, belonging to families commonly found at seeps (Mytilidae, Vesicomyidae, Thyasiridae) and to Lucinidae mostly encountered in littoral sulfide-rich sediments and at the shallowest seeps. Siboglinid polychaetes including a large vestimentiferan Lamellibrachia sp. were also associated. At least four bivalve species and one siboglinid are associated with symbiotic chemoautotrophic bacteria, as evidenced by Transmission Electronic Microscopy and isotopic ratio measurements. Among the bivalves, a mytilid harbors both methanotrophic and sulfide-oxidizing bacteria. Video spatial analysis of the community distribution on three volcanoes shows that dense bivalve shell accumulations (mainly lucinids) spread over large areas, from 10% to 38% of the explored areas (2500–15000 m 2 ) on the different volcanoes. Lamellibrachia sp. had different spatial distribution and variable density in the two mud volcano fields, apparently related with higher methane fluxes in the Anaximander volcanoes and maybe with the instability due to brines in the Olimpi area. The abundance and richness of the observed chemosynthetic fauna and the size of some of the species contrast with the poverty of the deep eastern Mediterranean.

The Florence Rise is a submarine feature extending from the island of Cyprus in the southeast to the Anaximander Mountains which form the northwestern end of the Cyprus Arc south of western Turkey, The eastern Florence Rise includes a topographic high near Cyprus while its central domain displays relatively low relief. Most of the major elements of relief appear to be bounded by faults, in the light of new geophysical data. An underlying 'core' ridge, likely made of pre-Pliocene nappes emplaced from the north, separates relatively undeformed sediments to the northeast from actively shearing sediments and seismic basement, to the southwest, A dextral arc-parallel wrench zone, at least 15 km wide, has created a lineated seafloor texture and accompanying flower structures within the central Florence Rise. Apparent Riedel type conjugate shears within this system cut across the Florence Rise and mark changes in the relief along the are, Several mud volcanoes are observed within the wrench zone and along associated faults. indicating that overpressuring at depth is relieved by these faults. There is no evidence for any typical subduction along this arcuate trend, which is considered to act as the present boundary between the African and Anatolian-Aegean plates. In contrast, both the nature of faulting and the morphology of the Florence Rise seem to indicate some degree of transpressional coupling between the two plates, even though they appear disconnected by a tectonic boundary in the form of a major shear zone. (C) 2002 Elsevier Science B.V. All rights reserved.

Details of the sea floor and of deformational styles of large portions of the central and eastern Mediterranean Ridge (MR) are revealed in recent 100% coverage swath bathymetry, acoustic imagery, together with continuons seismic profiling.The MR is a wide accretionnary wedge that results from convergente and ongoing incipient collision between Europe, Africa and the Anatolia-Aegea microplate, in Eastern Mediterranean.

Our understanding of the tectonic framework of the eastern Mediterranean has greatly improved in the past ten years or so. New research has benefited from deep sea drilling by the Ocean Drilling Program (ODP), the extensive use of new techniques such as multibeam swath mapping, unexpected results from investigations of mud volcanoes and fluid seeps, and exploration of areas of potential resources like the Nile offshore.

Aspects of the initial stages of a collision between European and African plates may have been documented in a geophysical survey of the central Mediterranean Ridge (MR) conducted last year. The idea of an incipient collision was first suggested by Finetti [1976],and details of the seafloor and tectonic deformation along the MR, revealed for the first time in the survey, seem to point in that direction. A unique opportunity may therefore exist for studying the beginnings of such a collision—between the passive margin of a major plate (Africa) acting as a continental indenter against the active margin of another plate (Europe). More wide angle data, deep penetrating multichannel seismic data, and drilling data are crucial to better assess the nature and the architecture of the underlying lithosphere, the styles of sedimentary deformation, and the consequences on fluid releases. Such data will make it possible to establish, or reject, a geodynamic collision model.

The north-eastern Alboran Sea in the SW Mediterranean is characterized by active tectonics. The principal neotectonic elements in the area result from an approximately N-S compression between Africa and Iberia (Woodside and Maldonado 1992). The elements include NE-SW oriented wrenches separated by intervening N-S and NNW-SSE strike-slip faults. It is these latter trends that are on the sonograph images. Variations in the direction of the principal stresses have allowed a switching of activity between the two systems. The NE-SW trending Serrata Fault system extends offshore into Almeria Bay and beyond towards the Alboran Ridge from the Cabo de Gata (Fig. 14.1). Recent movement on this system has been recorded onshore by dog-legged stream courses (Th. Roep, pers. comm.). The shelf is itself narrow along much of the margin (4–6 km wide), except for the Almeria Bay area (20 km). It has deep-sea canyons and their tributaries incised into it. The best developed of these is the Almeria Canyon, a channel which is effected by the active tectonics.

Erratum to ‘‘Evidence of methane venting and geochemistry of brines on mud volcanoes of the eastern Mediterranean Sea’’ [Deep-Sea Research I 50 (2003) 941–958] J.L. Charlou*, J.P. Donval, T. Zitter, N. Roy, P. Jean-Baptiste, J.P. Foucher, J. Woodside, MEDINAUT Scientific Party D! epartement of G! eosciences Marines, IFREMER Centre de Brest, DGRO/GM, BP 70, Plouzane Cedex 29280, France Faculty of Earth Sciences, Free University, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands Universit! e de Bretagne Occidentale, Avenue Le Gorgeu, Brest 29200, France LSCE-CEA/CNRS, Centre d’! etudes de Saclay, Gif sur Yvette 91191, France

A broad, multidisciplinary selection of scientists from across Europe and Russia met at a workshop, “Seafloor Carbon Fluxes via Methane,” in Strasbourg, France, to discuss a potentially important contribution to the global carbon budget. The quasi-steady state fluxes of seafloor methane are not currently considered to be significant contributors. However, this fact needs to be properly established by studying the sources and sinks of methane in seafloor sediments and the water column, and the related processes. Of perhaps greater significance is the potential for large episodic releases of methane; for example, from dissociation of gas hydrates, one of the seafloor methane sinks. Current global estimates of methane volume in marine gas hydrates vary by up to two orders of magnitude. Major new initiatives are under way around the world to study gas hydrates and seafloor methane fluxes and climatic fluctuations that may be related to massive conversion of methane from hydrate to gaseous form.

Three marine geophysical transects across the Banda Arc-Australian continent collision zone, east of Timor, north of Tanimbar and southeast of Seram show a variety of deformation patterns produced by the convergence. Seismic sequences observed in troughs and basins along these transects are tentatively correlated with the latest Cenozoic cycle chart. The sequences tentatively constrain the ages of the basins from Pliocene to Recent. In the troughs near the deformation front, Pliocene (5.5 Ma) to Recent undisturbed sediments are being accreted along the Timor and the Seram Transect. The forearc of both these transects shows deformed sediments. The Tanimbar Transect shows six basins on the Tanimbar structural high and deformation associated with strike slip and diapirism is observed. The deformation front on this transect consists of very closely spaced faults. The Weber Deep formed just prior to 5.5 Ma based on the tentative seismic sequence stratigraphy. A structural break in all 3 transects at a distance of about 45 km from the deformation front is postulated to relate to overriding of the base of the Australian continental slope.