New evidences of the interplay between a turbidite canyon (Guadiaro canyon, NW Alboran Sea) and current-driven along slope processes

Workshop. Alboran Domain and Gibraltar Arc: Geological Research and Natural Hazards - El dominio de Alborán y el Arco de Gibraltar: Investigación geológica y riesgos naturales - Le Domaine Alboran et l'Arch de Gibraltar: Recherche géologique et risques naturels, 16-18 octubre 2019, Granada..-- 2 pages, 1 figureThe NW Alboran Sea contains geological evidences of the intricate interplay of downslope and alongslope features on one hand, and of the interaction of the Atlantic Waters flowing out and the intermediate Mediterranean Waters (MWs) flowing into the Strait of Gibraltar on the other hand.Both of these interactions are of high scientific relevance and have been studied separately before, but must also be considered together since both phenomena occur simultaneously. The work is based on data acquired during the FAUCES surveys, comprising high-resolution bathymetry and seismic profiles, in combination with a database comprising seismic profiles acquired since the 70s. The interaction between downslope and alongslope processes occurs on both margins of the Alboran Sea, but this interaction is especially complex in the Spanish margin, where the turbidite canyons cut the continuity of terraced plastered drifts. The interaction may vary between the dominance of downslope processes over the alongslope processes (i.e., Almeria turbidite system), the alternation between downslope and alongslope deposits (which is the case of the most recent lobe of the Guadiaro fan) and the influence of alongslope processes over downslope processes. The Guadiaro canyon provides an example of the last case: After a first phase in which the canyon was incised, during a second phase (Pliocene) downslope processes were dominant, as indicated by the chaotic facies infilling the canyon incision. A last phase (Quaternary) characterized by stratified discontinuous facies indicate a greater influence of contourite alongslope deposits. During the stage two and mostly during stage three, the lateral accretion of packages (LAPs) of stratified facies with NE progradation trend have been recognized on its SW side (right margin), progressively invading of the Guadiaro Palaeocanyon and affecting its current location and shape (Fig. 1). These findings have been confirmed by isochore maps, in which a depocentre of Quaternary age runs parallel to the canyon on its SW side. The oceanography of the study area is marked by the closeness to the Strait of Gibraltar, located to the west. The Mediterranean intermediate waters, comprising Western Intermediate Waters (WIW), Levantine Intermediate Waters (LIW) and the upper portion of Tyrrhenian Dense Waters (TDWi), flow along the Spanish margin towards the Strait. On the opposite, the Atlantic Waters enter forming a strong jet into the Mediterranean. These two groups of water masses are separated by a pycnocline, along which internal waves formed in the Camarinal Sill travel eastwards. The NE progradation of the LAPs affecting the Guadiaro canyon points to the much stronger effect of the Atlantic Jet and the eastwardtravelling internal waves over the intermediate MWs directed towards the Strait of Gibraltar. Ultimately, these findings may shed light on one of the reasons behind the sudden abandonment and obliteration of the Estepona Palaeocanyon after the BQD, possibly located where the Atlantic Jet and the internal waves cease their sediment transport towards the NE and where the weaker SW transport by the intermediate Mediterranean Waters become the only alongslope transport mechanismContribution from Project FAUCES - CTM2015-65461-C2-R (MINECO/FEDER

Seismic hazard for the Trans Adriatic Pipeline (TAP). Part 2: broadband scenarios at the Fier Compressor Station (Albania)

AbstractTo ensure environmental and public safety, critical facilities require rigorous seismic hazard analysis to define seismic input for their design. We consider the case of the Trans Adriatic Pipeline (TAP), which is a pipeline that transports natural gas from the Caspian Sea to southern Italy, crossing active faults and areas characterized by high seismicity levels. For this pipeline, we develop a Probabilistic Seismic Hazard Assessment (PSHA) for the broader area, and, for the selected critical sites, we perform deterministic seismic hazard assessment (DSHA), by calculating shaking scenarios that account for the physics of the source, propagation, and site effects. This paper presents a DSHA for a compressor station located at Fier, along the Albanian coastal region. Considering the location of the most hazardous faults in the study site, revealed by the PSHA disaggregation, we model the ground motion for two different scenarios to simulate the worst-case scenario for this compressor station. We compute broadband waveforms for receivers on soft soils by applying specific transfer functions estimated from the available geotechnical data for the Fier area. The simulations reproduce the variability observed in the ground motion recorded in the near-earthquake source. The vertical ground motion is strong for receivers placed above the rupture areas and should not be ignored in seismic designs; furthermore, our vertical simulations reproduce the displacement and the static offset of the ground motion highlighted in recent studies. This observation confirms the importance of the DSHA analysis in defining the expected pipeline damage functions and permanent soil deformations

Understanding the complex geomorphology of a deep sea area affected by continental tectonic indentation: The case of the Gulf of Vera (Western Mediterranean)

19 pages, 11 figures, 1 table, supplementary data https://doi.org/10.1016/j.geomorph.2022.108126.-- Data availability: Casas, D., & UTM-CSIC. (2018). FAUCES-1 Cruise, RV Sarmiento de Gamboa [Data set]. UTM-CSIC. doi: 10.20351/29SG20170925 Comas, M. & UTM-CSIC. TOPOMED-GASBATS. Cruise, RV Sarmiento de Gamboa [Data set]. UTM-CSIC.doi: 10.20351/29SG20120517We present a multidisciplinary study of morphology, stratigraphy, sedimentology, tectonic structure, and physical oceanography to report that the complex geomorphology of the Palomares continental margin and adjacent Algerian abyssal plain (i.e., Gulf of Vera, Western Mediterranean), is the result of the sedimentary response to the Aguilas Arc continental tectonic indentation in the Eurasian–Africa plate collision. The indentation is imprinted on the basement of the margin with elongated metamorphic antiforms that are pierced by igneous bodies, and synforms that accommodate the deformation and create a complex physiography. The basement is partially covered by Upper Miocene deposits sealed by the regional Messinian Erosive Surface characterized by palaeocanyons that carve the modern margin. These deposits and outcropping basement highs are then covered and shaped by Plio-Quaternary contourites formed under the action of the Light Intermediate and Dense Deep Mediterranean bottom currents. Even though bottom currents are responsible for the primary sedimentation that shapes the margin, 97% of this region's seafloor is affected by mass-movements that modified contourite sediments by eroding, deforming, faulting, sliding, and depositing sediments. Mass-movement processes have resulted in the formation of recurrent mass-flow deposits, an enlargement of the submarine canyons and gully incisions, and basin-scale gravitational slides spreading above the Messinian Salinity Crisis salt layer. The Polopo, Aguilas and Gata slides are characterized by an extensional upslope domain that shapes the continental margin, and by a downslope contractional domain that shapes the abyssal plain with diapirs piercing (hemi)pelagites/sheet-like turbidites creating a seafloor dotted by numerous crests. The mass movements were mostly triggered by the interplay of the continental tectonic indentation of the Aguilas Arc with sedimentological factors over time. The indentation, which involves the progressively southeastward tectonic tilting of the whole land-sea region, likely generated a quasi-continuous oversteepening of the entire margin, thus reducing the stability of the contourites. In addition, tectonic tilting and subsidence of the abyssal plain favoured the flow of the underlying Messinian Salinity Crisis salt layer, contributing to the gravitational instability of the overlying sediments over large areas of the margin and abyssal plainThis research has been funding by the Spanish projects: DAMAGE (CGL2016-80687-RAEI/FEDER) and FAUCES (CTM2015-65461-C2-1-R); and the Junta de Andalucía projects: RNM-148 (AGORA) P18-RT-3275 and PAPEL (B-RNM-301-UGR18). [...] This work acknowledges to IGCP 640 - S4LIDE (Significance of Modern and Ancient Submarine Slope LandSLIDEs), and to the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S

Quando e perché i fondali dei nostri mari diventano pericolosi

La geologia e la morfologia dei fondali marini presentano la loro pericolosità, in particolare: canyon sottomarini, frane, faglie, erosione, processi deposizionali e fuoriuscite di fluidi. Silvia Ceramicola è ricercatrice presso l’Istituto di Oceanografia e di Geofisica Sperimentale di Trieste - OGS. Laureata in Scienze della Terra all’Università di Bologna, ha conseguito un dottorato di ricerca all’Università di Gent, in Belgio e una borsa Fulbright presso lo Scripps Oceanographic Institute di San Diego, dove ha sviluppato conoscenze specifiche sui processi geologici che avvengono sui fondali dei nostri oceani

Submarine Canyon dynamics - Executive summary

Ceramicola, S. ... et al.-- Submarine Canyon Dynamics in the Mediterranean and Tributary Seas - An integrated geological, oceanographic and biological perspective, 15-18 April 2015, Sorrento, Italy.-- 14 pages, 6 figures, 1 tableThis synthesis, sketched during the course of the workshop discussions, was developed and consolidated in the months thereafter thanks to further inputs, assembled by Silvia Ceramicola, that were received from the meeting participants. The editor, Frederic Briand, reviewed and edited the entire Monograph, with special attention to this opening chapter where his correspondence with Peter Harris, Pere Puig, Namik Çağatay, Marie-Claire Fabri and David Amblas was particularly useful. His gratitude is extended to Valerie Gollino for attending to the physical production of the Monograph under tighter deadlines than usualPeer Reviewe

Seismic evidence of small-scale lacustrine drifts in Lake Baikal (Russia).

High resolution, single-channel seismic sparker profiles across the Akademichesky Ridge, an intra-basin structural high in Lake Baikal (Russia), reveal the presence of small sediment mounds and intervening moats in the upper part of the sedimentary cover. Such features interrupt the generally uniform and even acoustic facies and are not consistent with the hemipelagic sedimentation, which is expected on such an isolated high and which would produce a uniform sediment drape over bottom irregularities. The influence of turbidity currents is excluded since the ridge is an isolated high elevated more than 600-1000 m above adjacent basins. The mounded seismic facies, including migrating sediment waves and non-depositional/erosional incisions, strongly suggest that sediment accumulation was controlled by bottom-current activity. We interpret the mounds as small-scale (< few tens of km2 in area) lacustrine drifts. Four basic types of geometry are identified: 1) slope-plastered patch sheets; 2) patch drifts; 3) confined drifts; 4) fault-controlled drifts. The general asymmetry in the sedimentary cover of the ridge, showing thicker deposits on the NWflank, and the common location of patch drifts on the northeast side of small basement knolls indicate that deposition took preferentially place at the lee sides of obstacles in a current flowing northward or sub-parallel to the main contours. Deep-water circulation in the ridge area is not known in detail, but there are indications that relatively cold saline water masses are presently flowing out of the Central Basin and plunging into the deep parts of the North Basin across the ridge, a process that appears to be driven mainly by small differences in salinity. We infer that the process responsible for the observed bottom-current-controlled sedimentary features has to be sought in these large-scale water-mass movements and their past equivalents. The age of the onset of the bottom-current-controlled sedimentation, based on an average sedimentation rate of 4.0 cm/ky, is roughly estimated to be as least as old as 3.5 Ma, which is generally regarded as the age of the onset of the last major tectonic pulse of rift basin development in the Baikal region

Episodic, rapid sea-level rises on the central Mediterranean shelves after the Last Glacial Maximum. A review

Submerged palaeo-shorelines on the central Mediterranean shelves, identified from high-resolution seismic profiles and bathymetric data, mark distinct water depths at which sea level stationed for a period of time during the relative sea-level rise that followed the Last Glacial Maximum (LGM). The shorelines are commonly represented by palaeo-coastal cliffs and barrier-beaches that lie today at water depths between −100 m and −70 m, and between −65 m and −40 m, in most places irrespective of the different tectonic contexts, even in the presence of significant vertical rates. These morphological features are thought to have been drowned during melt-water pulses 1A and 1B, which occurred between 15 and 10 ka. The evidence presented here confirms drowned shorelines documented elsewhere at similar water depths and shows that melt-water pulses have punctuated the post-glacial relative sea-level rise with rates up to 60 mm/yr. for a few centuries. The identification of morphological features related to melt-water pulses in the central Mediterranean Sea has important implications to improve our knowledge on episodes of rapid glacio-eustatic sea-level rise. This issue is critical to be able to forecast future sea-level rises in the Mediterranean, which is characterized by densely populated coasts and important coastal infrastructures

Multibeam bathymetry raw data (EM 120 echosounder entire dataset) of RV METEOR during cruise M70/1

Multibeam bathymetry raw data using the ship's own Kongsberg (Simrad) EM 120 multibeam echosounder was almost continuously recorded during RV METEOR cruise M70/1. Data were recorded on 23 days between 2006-09-24 and 2006-10-17. Data cover various areas in the Mediterranean Sea. The approximate average depth of the entire dataset is around 1900m. During data acquisition the Kongsberg EM 710 multibeam echosounder was occasionally running simultaneously during the survey. The data are archived at the Federal Maritime and Hydrographic Agency of Germany (Bundesamt für Seeschifffahrt und Hydrographie, BSH) and provided to PANGAEA database for data curation and publication. No ancillary sound velocity profiles (SVP) from the cruise are archived at the BSH, thus added to this dataset. However, data analysis of the raw data reveled that SVP has been changed on several occasions during the cruise. This publication is conducted within the efforts of the German Marine Research Alliance in the core area "Data management and Digitalization" (Deutsche Allianz Meeresforschung, DAM). Data are unprocessed and therefore may contain incorrect depth measurements (artifacts) without further processing. Data can be processed e.g. with the open source software package MB-System (Caress, D. W., and D. N. Chayes, MB-System: Mapping the Seafloor, http://www.mbari.org/products/research-software/mb-system/, 2021)

Multibeam bathymetry raw data (Kongsberg EM710 entire dataset) of RV METEOR during cruise M70/1

Multibeam bathymetry raw data using the ship's own Kongsberg EM 710 multibeam echosounder was almost continuously recorded during RV METEOR cruise M70/1. Data were recorded on 18 days between 2006-09-23 and 2006-10-15. Data cover various areas in the Mediterranean Sea. The approximate average depth of the entire dataset is around 640m. During data acquisition the Kongsberg (Simrad) EM 120 multibeam echosounder was occasionally running simultaneously during the survey. The data are archived at the Federal Maritime and Hydrographic Agency of Germany (Bundesamt für Seeschifffahrt und Hydrographie, BSH) and provided to PANGAEA database for data curation and publication. No ancillary sound velocity profiles (SVP) from the cruise are archived at the BSH, thus added to this dataset. However, data analysis of the raw data reveled that SVP has been changed on several occasions during the cruise. This publication is conducted within the efforts of the German Marine Research Alliance in the core area "Data management and Digitalization" (Deutsche Allianz Meeresforschung, DAM). Data are unprocessed and therefore may contain incorrect depth measurements (artifacts) without further processing. Data can be processed e.g. with the open source software package MB-System (Caress, D. W., and D. N. Chayes, MB-System: Mapping the Seafloor, http://www.mbari.org/products/research-software/mb-system/, 2021)

Vulcani di fango ed emissioni fluide nel prisma di accrezione della Calabria (Mar Ionio)

International audienceThe occurrence of mud volcanoes (MVs) in the deep Ionian Sea was first recognised in the early 1980s from the recovery of cores of mud breccia, initially hypothesised to record tectonic or diapiric processes, but eventually shown to record a long (> 1 Ma) history of seafloor extrusion from the accretionary prisms along the Europe-Africa subduction zone. Provinces of MVs were identified along the crest of the Mediterranean Ridge south and west of Greece, but few data were available from the Calabrian offshore until early in this century when new geophysical and geological data were acquired in the context of European-funded programmes. The acquisition of regional multibeam bathymetric and backscatter data, as well as seismic reflection profiles and cores from selected features, resulted in the discovery of a new province of MVs on the Calabrian accretionary prism (CAP), as well as insights into their activity through time. A total of 54 MVs were identified on the inner CAP across water depths of 150-2750 m from their distinctive morphologies and/or high backscatter character, in several cases proven by coring. Seismic reflection grids across two proven MVs showed them to record a history of activity dating back to an interpreted mid-Pliocene unconformity, one of the longest known records of extrusion. Sediment cores indicate recurrent eruptive episodes during the last glacial-interglacial cycle ( 1 Ma) processo di estrusione sul fondo marino avvenuto nei prismi di accrezione nella zona di subduzione Europa-Africa. Province di MV sono state identificate lungo la cresta del Mediterranean Ridge a sud e a ovest della Grecia, ma pochi dati relativi all’offshore calabrese sono stati disponibili fino all’inizio di questo secolo, quando nuovi dati geofisici e geologici sono stati acquisiti nel contesto di programmi finanziati dall’UE. L’acquisizione dei dati batimetrici e di backscatter multibeam, così come profili di sismica a riflessione e carotaggi hanno portato alla scoperta di una nuova provincia di MV sul prisma di accrezione calabrese (CAP), insieme a informazioni sulla loro attività nel tempo. Sulla CAP interna sono stati identificati 54 MV, a profondità comprese tra 150 e 2750 metri, identificati sulla base delle caratteristiche morfologiche e/o dell’elevato backscatter, supportati in diversi casi da carotaggi. Le registrazioni sismiche eseguite in corrispondenza di due MV hanno mostrato tracce di attività risalente a una discordanza del Pliocene medio, uno dei record di estrusione fra i più antichi. I campioni di sedimento indicano episodi eruttivi ricorrenti durante l’ultimo ciclo glaciale-interglaciale (<56 ka). Le indagini su diversi MV sommersi sono state realizzate utilizzando strumenti autonomi sottomarini (AUV) e strumenti teleguidati (ROV), che hanno identificato tracce di estrusione di brecce di fango e infiltrazioni di fluidi ricchi di gas associate a strutturecarbonatiche autigene, ecosistemi chemiosintetici e probabile formazione di gas-idrati. La provincia di MV nelle acque profonde della Calabria è un sistema attivo in cui gli episodi di estrusione possono dare origine a geohazard ricorrenti, separati da periodi più lunghi di quiescenza durante i quali la fuoriuscita di fluidi crea un collegamento tra geosfera e biosfera