Submarine geomorphology of the passage of Lanzarote (East Canary Islands region)

International Symposium on Marine Sciences (6º. 2018. Vigo)Centro Oceanográfico de Málaga, Instituto Español de Oceanografía, EspañaCentro oceanográfico de Cádiz, Instituto Español de Oceanografía, EspañaInstituto Geológico y Minero de España, EspañaFacultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, EspañaCentro Oceanográfico de Canarias, Instituto Español de Oceanografía, Españ

New discoveries of mud volcanoes on the Moroccan Atlantic continental margin (Gulf of Cádiz): morpho-structural characterization

10th International Conference on Gas in Marine Sediments, 6-11 September 2010, Listvyanka, RussiaDuring the MVSEIS-08 cruise of 2008, ten new mud volcanoes (MVs) were discovered on the offshore Moroccan continental margin (Gulf of Cádiz) at water depths between 750 and 1,600 m, using multibeam bathymetry, backscatter imagery, high-resolution seismic and gravity core data. Mud breccias were recovered in all cases, attesting to the nature of extrusion of these cones. The mud volcanoes are located in two fields: the MVSEIS, Moundforce, Pixie, Las Negras, Madrid, Guadix, Almanzor and El Cid MVs in the western Moroccan field, where mud volcanoes have long been suspected but to date not identified, and the Boabdil and Al Gacel MVs in the middle Moroccan field. Three main morphologies were observed: asymmetric, sub-circular and flat-topped cone-shaped types, this being the first report of asymmetric morphologies in the Gulf of Cádiz. Based on morpho-structural analysis, the features are interpreted to result from (1) repeated constructive (expulsion of fluid mud mixtures) and destructive (gravity-induced collapse and submarine landsliding) episodes and (2) interaction with bottom currentsDivisión de Geología Marina, Instituto Geológico y Minero de España, EspañaCentro Oceanográfico de Málaga, Instituto Español de Oceanografía, EspañaFacultad de Ciencias del Mar, Universidad de Cádiz, EspañaFacultad de Ciencias Geológicas, Universidad Complutense de Madrid, Españ

Seafloor environments on Madrid and El Cid mud volcanoes (Moroccan continental margin of the Gulf of Cádiz)

Simposio sobre el Margen Ibérico Atlántico (9º. 2018. Coimbra, Portugal)More than 70 mud volcanoes (MVs) are identified along the continental margin of the Gulf of Cadiz,,although only a few have been thoroughly sampled and direct observed. This work is a contribution to the knowledge of the Gulf of Cadiz MVs Madrid and El Cid, located in the continental slope known as Western Moroccan Field over 1300 m water depth. On Madrid MV extensive crusts and mud breccia were observed. Nevertheless in El Cid MV, the rocky fragments are of smaller size and mud breccia has not been sampled/observed on the surface. In both MVs, coral reefs colonizing rocky fragments and covering seafloor of metric size have been observed.Departamento de Ciencias de la Tierrra, Universidad de Cádiz, EspañaCentro Oceanográfico de Málaga, Instituto Español de Oceanografía, EspañaCentro oceanográfico de Cádiz, Instituto Español de Oceanografía, EspañaInstituto Geológico y Minero de España, EspañaEstrutura de Missão para a Extensão da Plataforma Continental, Portuga

Subsurface Geophysics and Geology (GEOFSU

[EN] The geophysics line at the IGME began in 1927 as a Geophysics Sectiondedicated to subsurface exploration. During all this time, it has been developed in order to support and give expert service in all IGME’s activities both as a geological service and public research institution, as well as a research and development work itself. On the other hand, in recent years the IGME has promoted a line of research aimed at the characterization and 3D modeling of geological structures and formations, the development of dedicated software and the evolution and sophistication of computer equipment. The new scenario of incorporation of the IGME to the CSIC as a national reference center in the field of Earth Sciences has allowed the establishment of the GEOFSUB Research Group (Subsurface Geophysics and Geology). It is constituted by 21 members who had been collaborating regularly of the IGME former scientific-technic areas Geophysics and remote sensing (Área de Geofísica y Teledetección) and Subsurface geology and 3D geological modelling (Área de Geología del Subsuelo y Modelización Geológica 3D). Our main differentiating element is our extensive knowledge of geophysical and geological techniques, which allows us to characterize the subsoil in an optimal waPeer reviewe

BSRs levels in the west Antarctic Peninsula margin: an inventory of seismic indicators of marine gas hydrates

European Conference on Gas Hydrate (ECGH 2022), 13-16 June 2022, LyonIn the frame of ICEFLAME project (PID2020-114856RB-I00, Spanish Ministry of Science and Innovation), an inventory of BSRs levels in the west Antarctic Peninsula margin has been carried out. The aim of this inventory is to assess the theoretical transient state of these geological structures due to the global ice-sheet retreat in the Polar Regions.In the west Antarctic Peninsula margin, three areas with characteristics BSR levels have been found: (i) north South Shetland Islands (reported in previous studies, (ii) North Bransfield Island (Bransfield Strait, AP margin), and (iii) Anvers Island (AP margin). North of the South Shetland Islands, BSR levels had been reported in between the Elephant–King George islands accretionary wedge sector (Lodolo et al., 1993). Two extensive and discontinuous BSR levels (named BSR-1 and BSR-2) have been mapped in the inventory. The BSR-1 appears as local, disconnected and discontinuous patches, about 10 km diameter in geographical extension, of high amplitude reflections of inverse polarity. Its burial depth ranges from ca. 150-200 ms TWT (at the base of the accretionary wedge) to ca. 300 ms TWT (in the middle slope). BSR-2 shows more extensive spatial continuity than BSR-1. BSR-2 levels are well-defined high amplitude reflections of inverse polarity. They simulate the seafloor increasing the burial-depth with water depth from ca. 250 ms TWT in the upper slope to ca. 1s TWT at the base of the accretionary wedge. North off Bransfield Island, BSR levels had been reported in the distal continental shelf of the Antarctic Peninsula margin (Oliveira, 2017). The BSR in this area constitutes a continuous high amplitude reflection of inverse polarity. It shows a shallow and homogeneous burial depth ranging from 145 to 170 ms TWT. South of Anvers Island, a BSR level had been reported to the west of the island in the middle continental shelf of the Antarctic Peninsula margin (Solovyov et al., 2017). Here, the BSR forms an isolated patch of ca. 13 km of extension at a burial depth of ca. 150-200 ms TWT. It shows high amplitude, inverse polarity and a clear cross cutting character. All of the above BSR levels seem to be in a transient state with respect to their theoretical locations calculated from both pure methane and thermogenic compositions. We put forward two hypothesis for such situation: isostatic rebound and tectonic uplift and/or the presence of overpressured sediments. References Lodolo, E., Camerlenghi, A., Brancolini, G., 1993. A bottom simulating reflector on the South Shetland margin, Antarctic Peninsula. Antarct. Sci. 5. https://doi.org/10/bfcb22 Oliveira, M.L.L., 2017. Tectonic Characterization of the Central Bransfield Strait Using Seismic Reflection Data, Degree of Bachelor in Geophysics. Universidade Federal Fluminese. Instituto de Geociencias., Niterói – RJ, Brasil. Solovyov, V.D., Levashov, S.P., Yakimchuk, N.A., Korchagin, I.N., Bozhezha, D.N., 2017. The experiment of integrated mobile technologies used for deep hydrocarbon accumulation prospecting and geophysical mapping at the West Antarctic bottom structures. Geofiz. Zhurnal 39, 123–143. https://doi.org/10/gm8mf7Peer reviewe

Geological and tectonic controls in Spanish submarine landslides

Simposio sobre el Margen Ibérico Atlántico (9º. 2018. Coimbra, Portugal)Morphometric parameters of the submarine landslides reveal a relationship between the geological and tectonic controls where they have developed. Three main groups with significant differences between minimum or maximum bathymetry versus sphericity are defined: deep mid-ocean spreading ridges, volcanic islands and continental margins. While minimum bathymetry versus sphericity in continental margins show no significant association, deep mid-ocean spreading ridges show a positive association, with larger values of sphericity along the increasing values of minimum bathymetry. On the contrary, landslides in volcanic islands display a negative association of these variables, with lower values of sphericity associated with higher values of minimum bathymetry.Instituto Geológico y Minero de España, Españ

Marine Gas Hydrate Geohazard Assessment on the European Continental Margins: the Impact of Critical Knowledge Gaps

23 p. - Data used in this paper are available in a public and permanent repository (https://data.mendeley.com/datasets/vbt6hspgpn/draft?preview=1, (accessed on 20 March 2020)) with doi:10.17632/vbt6hspgpn.1.[EN] This paper presents a geohazard assessment along the European continental margins and adjacent areas. This assessment is understood in the framework of the seafloor’s susceptibility to (i.e., likelihood of) being affected by the presence of hydrate deposits and the subsequent hazardous dissociation processes (liquefaction, explosion, collapse, crater-like depressions or submarine landslides). Geological and geophysical evidence and indicators of marine gas hydrates in the theoretical gas hydrate stability zone (GHSZ) were taken into account as the main factors controlling the susceptibility calculation. Svalbald, the Barents Sea, the mid-Norwegian margin-northwest British Islands, the Gulf of Cádiz, the eastern Mediterranean and the Black Sea have the highest susceptibility. Seafloor areas outside the theoretical GHSZ were excluded from this geohazard assessment. The uncertainty analysis of the susceptibility inference shows extensive seafloor areas with no data and a very low density of data that are defined as critical knowledge gaps.This research was funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 731166, GARAH project (GeoERA- GeoE.171.002 GE-1), EMODnet Bathymetry—High Resolution Seabed Mapping (EASME/EMFF/2018/007).Peer reviewe

Evidence of episodic long-lived eruptions in the Yuma, Ginsburg, Jesús Baraza and Tasyo mud volcanoes, Gulf of Cádiz

High-resolution single channel and multichannel seismic reflection profiles and multibeam bathymetric and backscatter data collected during several cruises over the period 1999 to 2007 have enabled characterising not only the seabed morphology but also the subsurface structural elements of the Yuma, Ginsburg, Jesús Baraza and Tasyo mud volcanoes (MVs) in the Gulf of Cádiz at 1,050–1,250 m water depth. These MVs vary strongly in morphology and size. The data reveal elongated cone-shaped edifices, rimmed depressions, and scarps interpreted as flank failures developed by collapse, faulting, compaction and gravitational processes. MV architecture is characterised by both extrusive and intrusive complexes, comprising stacked edifices (including seabed cones and up to four buried bicones) underlain by chaotic vertical zones and downward-tapering cones suggesting feeder systems. These intrusive structures represent the upper layer of the feeder system linking the fluid mud sources with the constructional edifices. The overall architecture is interpreted to be the result of successive events of mud extrusion and outbuilding alternating with periods of dormancy. Each mud extrusion phase is connected with the development of an edifice, represented by a seabed cone or a buried bicone. In all four MVs, the stacked edifices and the intrusive complexes penetrate Late Miocene–Quaternary units and are rooted in the Gulf of Cádiz wedge emplaced during the late Tortonian. Major phases of mud extrusion and outbuilding took place since the Late Pliocene, even though in the Yuma and Jesús Baraza MVs mud volcanism started in the Late Miocene shortly after the emplacement of the Gulf of Cádiz wedge. This study shows that fluid venting in the eastern sector of the Gulf of Cádiz promoted the outbuilding of large long-lived mud volcanoes active since the Late Miocene, and which have been reactivated repeatedly until recent times.This work is a contribution to the SUBVENT Project (CGL2012-39524-C02-02) and the Extension of the Spanish Continental Shelf Project (CTM2010-09496-E).Peer reviewe

Geological and tectonic controls on morphometrics of submarine landslides of the Spanish margins

19 pages, 7 figures, 4 tablesA geomorphological analysis of the submarine landslides geographical information system catalogue of the Geological Survey of Spain has revealed three main groups of submarine landslides associated with (1) deep-ocean seamount ridges (extinct spreading centres), (2) volcanic islands and (3) continental margins. These three groups have statistically significant morphometric differences, as determined from analysis of variance (ANOVA) and Tukey's HSD Tests, in total length (runout), total area, maximum deposit width and bathymetric depth. Volcanic island-related slope failures affect larger areas of the seafloor and their headwall escarpments often extend above sea-level. Slope failures associated with seamount ridges are the deepest, between 3500 and 5500 m, and display relatively high width-to-length ratios. Finally, landslides on continental margins show two sub-groups. Landslides on tectonically controlled margins have smaller runouts and total area and larger average slope gradients than margins where tectonic controls are limited. These results demonstrate that submarine landslide morphology is strongly controlled by the geological-tectonic settingThis work has been supported by the EU-funded projects GARAH (GeoERA GE-1), EMODnet High Resolution Seabed Mapping (EASME/EMFF/2015/1.3.1.7/SI2.74125) and EMODnet Bathymetry–High Resolution Seabed Mapping (EASME/EMFF/2018/007). Funding was provided by the ‘Ministerio de Ciencia, Innovación y Universidades’ and the European Regional Development Fund through project INSIGHT (CTM2015-70155-R)Peer reviewe

Onshore and offshore geomorphological features of the El Golfo debris avalanche (El Hierro, Canary Islands)

7th International Symposium on Submarine Mass Movements and Their Consequences, 1-4 November 2015, Wellington, New ZealandThis study shows an onshore-offshore morpho-structural characterization of the El Golfo flank collapse and debris avalanche on El Hierro (Canary Islands, Spain). Erosive and depositional features have been identified based on: LIDAR topography and geology from water galleries (onshore); and high-resolution 3.5 kHz and multichannel seismic reflection profiles, and multibeam data (offshore). The onshore headwall scarp shows a non-continuous profile formed by two semi-circular amphitheatres and extends offshore by a smooth chute. The chute ends at about 3000-3200 m water depth in the distal depositional area. Multichannel seismic profiles show two major subunits of chaotic reflectors in the debris avalanche deposits. Results suggest that the El Golfo debris avalanche event likely took place in multiple stages. Consequently, we suggest that the multistaged nature of El Golfo debris avalanche greatly reduces the tsunamigenic potential of these flank collapsesPeer Reviewe