Tragsa SGP

Madrid, Spain

Tragsa SGP

Madrid, Spain
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Munoz A.,Tragsa SGP | Acosta J.,Spanish Institute of Oceanography | Cristobo J.,Spanish Institute of Oceanography | Druet M.,Spanish Institute of Oceanography | Uchupi E.,Woods Hole Oceanographic Institution
Earth-Science Reviews | Year: 2013

We study an area little known of the Atlantic Patagonian margin from 44°30'S to 47°40'S and from 59°W to nearly 61°W. The multi-beam bathymetry coupled with high resolution seismic reflection profiles, has provided details on the morphology and shallow acoustic structure on this area.The main morphological characteristics of the seafloor features on the shelf and middle slope are described. The Atlantic Patagonian continental shelf north of 45°40'S is located at a depth of 170-200. m, south of this latitude the shelf edge is at 128 to 200. m. The shelf surface is marred by circular depression and ridges oriented oblique to the shelf edge. The upper slope and upper middle slope are plowing by icebergs from Antarctica in Pleistocene and local reefs of cold-water coral further enhance the topography of the area. In the middle slope there are two terraces, the 20 to 60. km wide Nágera and the 15 to 60. km wide Perito Moreno terraces, showing moats, hollows, pot holes, sediment drifts and sediment waves. The terraces may have been formed in Late Miocene whereas the other forms are of Pleistocene age. Other features are a sediment swell south of 47°S and seven submarine canyons on the middle slope. These incipient canyons have been developed in the middle slope by retrogressive erosion, some terminating on the upper middle slope, and others on the upper slope and the Canyon 6 breaching the shelf edge.Individual seafloor features existing on the Atlantic Patagonian Margin have been classified into two main groups according to their origin: along and across-slope processes. These primary agents were supplemented by endogenic processes such as expulsion of gas/water, diapirism of high-pressure mud and folding/faulting. The results suggest that today down-slope processes on the slope are practically non-existent and that the morphology of the upper and middle slope is slowly being remolded by along-slope bottom currents. © 2013 Elsevier B.V.

Gomez de la Pena L.,CSIC - Institute of Marine Sciences | Gracia E.,CSIC - Institute of Marine Sciences | Munoz A.,Tragsa SGP | Acosta J.,Spanish Institute of Oceanography | And 3 more authors.
Tectonophysics | Year: 2016

The Palomares continental margin is located in the southeastern part of Spain. The margin main structure was formed during Miocene times, and it is currently part of the wide deformation zone characterizing the region between the Iberian and African plates, where no well-defined plate boundary occurs. The convergence between these two plates is here accommodated by several structures, including the left lateral strike-slip Palomares Fault. The region is characterized by sparse, low to moderate magnitude (Mw <. 5.2) shallow instrumental earthquakes, although large historical events have also occurred. To understand the recent tectonic history of the margin we analyze new high-resolution multibeam bathymetry data and re-processed three multichannel seismic reflection profiles crossing the main structures. The analysis of seafloor morphology and associated subsurface structure provides new insights of the active tectonic features of the area. In contrast to other segments of the southeastern Iberian margin, the Palomares margin contains numerous large and comparatively closely spaced canyons with heads that reach near the coast. The margin relief is also characterized by the presence of three prominent igneous submarine ridges that include the Aguilas, Abubacer and Maimonides highs. Erosive processes evidenced by a number of scars, slope failures, gullies and canyon incisions shape the present-day relief of the Palomares margin. Seismic images reveal the deep structure distinguishing between Miocene structures related to the formation of the margin and currently active features, some of which may reactivate inherited structures. The structure of the margin started with an extensional phase accompanied by volcanic accretion during the Serravallian, followed by a compressional pulse that started during the Latemost Tortonian. Nowadays, tectonic activity offshore is subdued and limited to few, minor faults, in comparison with the activity recorded onshore. The deep Algero-Balearic Basin is affected by surficial processes, associated to halokinesis of Messinian evaporites. © 2016 Elsevier B.V.

Acosta J.,Spanish Oceanographic Institute | Fontan A.,Spanish Oceanographic Institute | Munoz A.,Tragsa SGP | Munoz-Martin A.,Complutense University of Madrid | And 2 more authors.
Marine and Petroleum Geology | Year: 2013

Multi-beam bathymetry and high-resolution low-penetration seismic reflection profiles of the offshore extensions of the Bétic Internal Zone off Sierra de Cartagena-La Unión margin along its south side and the Mar Menor margin along its east side, the Mazarrón Escarpment forming its southern boundary and the adjacent oceanic Algero-Balearic basin have provided images of the neo-tectonic structures of the region equal to those provided by subaerial photography. For the first time we mapped with unprecedented detail the Mazarrón Escarpment and the Southeast margin of Iberia.The first-order structures of the region are due to the consequence of the collision of the African and Eurasian plates during the Alpine orogeny in late Oligocene-Middle Miocene, the westward migration of the Alborán plate in the Middle Miocene and the desiccation of the Mediterranean in the Messinian (Late Miocene) that led to the deposition of evaporites in the Algero-Balearic basin and erosion of the Mazarrón Escarpment, the Sierra de Cartagena-La Unión shelf, the Mar Menor margin and the adjacent coast. Our data images second order tectonic features (neo-tectonic features) superimposed on the larger structures. These include the deformation of the strata in the Algero-Balearic basin by the gliding of the Plio-Quaternary sediments on Messinian halite on the margins of the basin and sediment loading in its center, the Late Miocene-Quaternary deformation of the area north of the Mazarrón Escarpment resulting from the continuous oblique convergence of the African and Eurasian plates in a NNW-SSE direction, the Miocene to Pleistocene volcanic edifices and pinnacles (dikes), the pockmarks formed by the extrusion of gas/water via faults and the massive gravitational failure of the Mazarrón Escarpment triggered by this plate convergence. The data also show in detail features formed on the Mazarrón Escarpment during the Messinian, Pliocene and Pleistocene regressions and those on the shelf formed during the Pleistocene glacially induced regressions/transgression and sediment drifts generated by modern currents. © 2013 Elsevier Ltd.

Gomez-Ballesteros M.,Spanish Institute of Oceanography | Druet M.,Spanish Institute of Oceanography | Munoz A.,Tragsa SGP | Arrese B.,Spanish Institute of Oceanography | And 8 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2014

The Avilés Canyon System (ACS) is a complex, structurally-controlled canyon and valley system constituted by three main canyons of different morphostructural character. They are, from east to west: La Gaviera Canyon, El Corbiro Canyon and Avilés Canyon. In addition to this ACS, a new canyon has been surveyed: Navia Canyon.We present for the first time a high resolution multibeam map showing with great detail the morphological and structural complexity of this segment of the Cantabrian margin.ACS presents a tectonic imprint marked by NW-SE, NNE-SSW and E-W structures. The morphology of their reaches as well as their single mouth, in addition to some rock dredges in their major valleys, demonstrates active down-slope flushing.The continental shelf shows a flat, uniform slope with local and well defined rock outcrops south of Aviles Canyon head. Sedimentary zones are limited, showing thin unconsolidated sedimentary cover.Strong continental margin water dynamics avoid thicker sediment deposition, being littoral sedimentary dynamics responsible for transport to the canyons heads and conduit to the Biscay Abyssal plain.Biscay Abyssal Plain shows evidence of a strong westward current affecting the surveyed strip of this more than 10. km wide plain. Presence of two parallel deep sea channels, erosive scarps, and erosion of gully divides on the lower slope, may indicate that this is part of the distal fan at the termination of the large turbiditic system fed by Cap Ferret, Capbreton and other large canyons (Santander, Torrelavega, Lastres and Llanes) to the west of ACS. © 2013 Elsevier Ltd.

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