1,720,998 research outputs found
Recent tectonics and Mesozoic inherited structures in the offshore of the Central-Southern Adria Plate
No full textRelation between recent tectonics and Mesozoic inherited structures of the central-southern Adria plate
No full textThe analysis of several seismic reflection profiles offshore the Adria plate reveals acomplex spatial-temporal distribution of the carbonate platforms, often linked todifferent conditions of the crustal thicknesses. The “platform sequence”, the“platform-to-basin sequence” and the “oceanic sequence” seem to represent theprincipal paleogeographic domains and are associated with different crustal typeswhich, during the Tertiary age, became the foreland of the southernApennine/Calabrian Arc and the Dinaric/Hellenic Chain. In this work, we have triedto highlight how these main crustal domains affect recent tectonics in a remarkableway. The migration of the Calabrian Arc and the Hellenic Chain brought about aregional compressive regime, which currently affects the whole crustal thickness ofthe Adria plate, causing transpression along the main strike-slip systems of the plate,inversion tectonics in the Salento offshore, and underthrusting below the Dinaric front,whereas the external front of the central-southern Apennines does not seem to beactive any more
Gas hydrates and active fluid outflow NE of the South Shetland Islands, Antarctic Peninsula
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Geophysical exploration of the West Sardinian continental margin and Sardo-Provençal oceanic basin (West Mediterranean Sea)
No full textGeophysical exploration of the West Sardinian continental margin and Sardo-Provencal oceanic basin (West Mediterranean Sea).
Del Ben A.1, Geletti, R.2, Zgur F.2, Brancatelli G.2, Camerlenghi A.2, Dal Cin M.2, Fais S. 3,
Forlin E.2, Lanzoni A.1, Romeo R.2
1 Dipartimento di Matematica e Geoscienze, Università di Trieste.
2 Istituto Nazionale do Oceanografia e di Geofisica Sperimentale OGS, Trieste.
3 Dipartimento di Ingegnaria Civile, Ambientale e Architettura, University of Cagliari
Corresponding author: [email protected]
Keywords: West-Sardinian margin, Sardo-Provencal Basin, Seismic reflection, Messinian, Evaporites
The Sardo-Provencal Basin and its eastern continental West Sardinian margin represents one of the less explored Italian sea. During the year 2010 the Explora acquired a new geophysical dataset (W-Sardinia_2010) represented by seismic reflection and chirp profiles and Multibeam and Magnetic data. The dataset acquisition was designed on the base of results provided by previous seismic profiles of the MS (Mediterranean Sea), CROP (CROsta Profonda) and ViDEPI (Visibility of Petroleum Exploration Data, public data available in the Sardinian offshore, near the shoreline) projects. Integration of all the different dataset allowed us to interpret the main geological structures produced during the Upper Oligocene-Lower Miocene, when the rifting phase was followed by the oceanic opening of the West Mediterranean Sea. On the continental margin seismic waves have explored the whole sedimentary sequence, reaching the geological basement and showing the horst and graben system produced by the extensional tectonics (Geletti et al., 2014; Dal Cin et al., 2016; Del Ben et al., 2018).
On the oceanic abyssal plain the MS and CROP profiles depicted some deep reflectors, generally ascribed to the top of the basaltic basement, while not good information is available about the Moho reflector. The new W-Sardinia_2010 dataset, due to its higher resolution, highlights very clearly the Messinian evaporate sequence, characterized by the typical Messinian trilogy (Rehault et al., 2004).
The evaporate sequence is represented by i) a high amplitude stratified upper unit (UU), of mainly gypsum lithology, ii) a transparent salt unit (MU for Mobile Unit), characterized by strong halocinetic tectonics, and iii) a stratified lower unit (LU), never crossed by boreholes, probably also represented by gypsum. This trilogy gradually onlaps the lower continental slope, disappearing toward east, substituted by a marked erosional truncation (MES, for Margin Erosional Surface: Lofi et al., 2011) representing a variable hiatus, locally evident also in the Sardinia onshore.
The Plio-Quaternary sequence, clearly depicted by the seismic reflection, was highly deformed, especially during the Lower Pliocene, by halocinetics. Sometimes this process is still active, producing some circular structures in the sea bottom, which are well imaged in detail by the chirp and multibeam data.
The different resolution of the available data represents the best condition to study the whole sedimentary sequence and to correlate deep structures with their local effect on shallow youngest sediments.
References
Dal Cin M., Del Ben A., Mocnik A., Accaino F., Geletti R., Wardell N., Zgur F. & Camerlenghi A. (2016) - Seismic imaging of Late Miocene (Messinian) evaporites from Western Mediterranean back-arc basins. Petr. Geosci. 22, 297–308.
Del Ben, A., Mocnik A., Camerlenghi A., Geletti R., Zgur F., 2018. – 9.A-D- Western Sardinia. In: J. Lofi, Ed., Seismic atlas of the Messinian Salinity Crisis markers in the Mediterranean sea. Volume 2. - Mem. Soc. geol. fr., n.s., 2018, t. 181, and Commission for the Geological Map of the World, 32-35.
Geletti R., Zgur F, Del Ben A. , Buriola F. , Fais S., Fedi M., Forte E., Mocnik A., Paoletti V., Pipan M., Ramella R.,. Romeo R., Romi A. (2014) - The Messinian Salinity Crisis: new seismic evidence in the West-Sardinian Margin and Eastern Sardo-Provençal Basin (West Mediterranean Sea). Marine Geology, 351, 76–90.
Lofi, J., Deverchère, J., Gaullier, V., Gillet, H., Gorini, C., Guennoc, P., Loncke, L., Maillard, A., Sage, F., Thinon, I. (2011). Atlas of the Messinian seismic markers in the Mediterranean and Black Seas. Memoir Societe Geologique de France n.s. 179 and World Geological Map Commission (72 pp.).
Rehault, J.P., Boillot, G., Mauffret, A., 1984. The Western Mediterranean Basin geological evolution. Marine Geology 55, 447–477
IONIAN BASIN
No full textThe Ionian basin is the remnant of a wide sedimentary basin floored by oceanic crust. It was originated after the Permo-Triassic lithospheric rifting between the Africa megaplate and the Adria continental block [Finetti, 1982; Stampfli et al., 2001].
The rifting phase produced deep grabens on a thinned continental crust; successively, the oceanic opening of Ionian basin was accompanied by the NE migration of the Adria plate and its counterclockwise rotation.
During the Paleogene-Miocene time the north-western Ionian crust has been subducted below the Southern Apennine Maghrebian orogenic belt. After the collision between the orogenic belt and the continental Adria and Pelagian forelands during the Upper Miocene, only the Calabrian Arc is still migrating and overthrusting the oceanic foreland with a SSE direction [Del Ben et al., 2008]. To the East, the Ionian basin is subducting under the Hellenic Arc, cut by the Cephalonia active right-lateral strike-slip fault system (Fig. X.2) and the Mediterranen Ridge accretionary wedge. The southern margin of the Ionian basin is a rifted margin formed by the transition to the Africa plate continental crust in the Sirte Gulf.
The seismic facies of the MSC unconformities and units are described
CYPRUS ARC
No full textThe Cyprus Arc, in the northeastern Mediterranean, represents the convergent zone between the African, Arabian and European plates, with the intermediate westerly escaping Aegean–Anatolian microplate. The arc is regionally characterized by south-verging thrusts related to northward subducton of the African plate.
Compressional deformation initiated in the Late Cretaceous and produced several basins inner the arc, which are separated through regional rises [Biju-Duval et
al., 1976]. The rather complex evolution of the region developed as an ophiolitic suture and prosecuted in Eocene and late Miocene shaping an arcuate fold-thrust belt. The compressive fault systems has been often reactivated, after the end of Miocene, by the transpressional regime [Hall et al., 2005; Calon et al., 2005; Bowman, 2001]. Generally, the different basins show defferent evolution, in both space and time. They were already mainly shaped when the Messinian Salinity
Crisis started and evaporites deposited with different thickness. These basins, which were successively involved in the Plio-Quaternary tectonics, show mobilization of salt by compression or sliding, mainly occurred during the Pliocene time.
The seismic facies of the MSC unconformities and units are described
Evidenze di gas-seepage associate a strutture tettoniche profonde in Mare Adriatico Centrale
No full textThe analyses of chirp sub-bottom profilers and multibeam data acquired during several surveys of the R/V OGS Explora, and their correlation with multichannel seismic profiles, have highlighted the presence of gas seepages, fracture systems and deep salt features present in the Central Adriatic Sea. Their distribution shows a strict relation between their mutual development
Relazioni tra “cold seeps”, “bright spots” e strutture profonde nel canale di Otranto, Sud Adriatico
No full textPreliminary geophysical study of the sedimentary cover and the rifting of the Ross Sea (Antarctica)
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