scholarly journals The Crustal Domains of the Alboran Basin (Western Mediterranean)

Tectonics ◽  
2018 ◽  
Vol 37 (10) ◽  
pp. 3352-3377 ◽  
Author(s):  
Laura Gómez de la Peña ◽  
César R. Ranero ◽  
Eulàlia Gràcia
Keyword(s):  
Western Mediterranean ◽  
Alboran Basin

scholarly journals The Mediterranean outflow in the Strait of Gibraltar and its connection with upstream conditions in the Alborán Sea

Ocean Science ◽  
2017 ◽  
Vol 13 (2) ◽  
pp. 195-207 ◽  
Author(s):  
Jesús García-Lafuente ◽  
Cristina Naranjo ◽  
Simone Sammartino ◽  
José C. Sánchez-Garrido ◽  
Javier Delgado
Keyword(s):  
Potential Temperature ◽  
Western Mediterranean ◽  
Altimetry Data ◽  
Alboran Sea ◽  
Strait Of Gibraltar ◽  
Mediterranean Outflow ◽  
Alboran Basin ◽  
In Situ Observations ◽  
Alborán Sea

Abstract. The present study addresses the hypothesis that the Western Alborán Gyre in the Alborán Sea (the westernmost Mediterranean basin adjacent to the Strait of Gibraltar) influences the composition of the outflow through the Strait of Gibraltar. The process invoked is that strong and well-developed gyres help to evacuate the Western Mediterranean Deep Water from the Alborán basin, thus increasing its presence in the outflow, whereas weak gyres facilitate the outflow of Levantine and other intermediate waters. To this aim, in situ observations collected at the Camarinal (the main) and Espartel (the westernmost) sills of the strait have been analysed along with altimetry data, which were employed to obtain a proxy of the strength of the gyre. An encouraging correlation of the expected sign was observed between the time series of potential temperature at the Espartel Sill, which is shown to keep information on the outflow composition, and the proxy of the Western Alborán Gyre, suggesting the correctness of the hypothesis, although the weakness of the involved signals does not allow for drawing definitive conclusions.

scholarly journals The Meandering Path of a Drifter around the Western Alboran Gyre

2004 ◽  
Vol 34 (3) ◽  
pp. 685-692 ◽  
Author(s):  
Jesús García Lafuente ◽  
Javier Delgado
Keyword(s):  
Mediterranean Sea ◽  
Surveillance System ◽  
Relative Vorticity ◽  
Western Mediterranean ◽  
Tidal Currents ◽  
Strait Of Gibraltar ◽  
Short Scale ◽  
Western Mediterranean Sea ◽  
Alboran Basin ◽  
Drifter Trajectory

Abstract An accidentally released drifter in the eastern section of the Strait of Gibraltar, whose successive positions were tracked by the Argos surveillance system, was advected more than 170 km around the western Alboran gyre in the Alboran Sea of the western Mediterranean Sea during four days. The drifter trajectory along the gyre's periphery was wavelike around a hypothetical smoothed streamline, with a period of 35 h and an amplitude of approximately 2 km. Temperature observations confirm the wavelike nature of the trajectory. Neither tidal currents within the Alboran basin nor wind-related forcing are able to explain the observed path. The interaction of the incoming Atlantic jet and the western Alboran gyre at the place where they meet together with the existence of relative vorticity pulses of the Atlantic jet associated with tidal currents in the strait is put forward as a likely mechanism that generates short-scale eddies in which the drifter could have been trapped. The subsequent advection of such an eddy around the gyre would depict the observed wavelike trajectory.

scholarly journals Plio-Quaternary tectonic evolution of the southern margin of the Alboran Basin (Western Mediterranean)

Solid Earth ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 741-765 ◽  
Author(s):  
Manfred Lafosse ◽  
Elia d'Acremont ◽  
Alain Rabaute ◽  
Ferran Estrada ◽  
Martin Jollivet-Castelot ◽  
...  
Keyword(s):  
Fault Zone ◽  
Tectonic Evolution ◽  
Long Term Evolution ◽  
Western Mediterranean ◽  
Strike Slip ◽  
Term Evolution ◽  
Southern Margin ◽  
Constant Direction ◽  
Alboran Basin

Abstract. Progress in the understanding and dating of the sedimentary record of the Alboran Basin allows us to propose a model of its tectonic evolution since the Pliocene. After a period of extension, the Alboran Basin underwent a progressive tectonic inversion starting around 9–7.5 Ma. The Alboran Ridge is a NE–SW transpressive structure accommodating the shortening in the basin. We mapped its southwestern termination, a Pliocene rhombic structure exhibiting series of folds and thrusts. The active Al-Idrissi Fault zone (AIF) is a Pleistocene strike-slip structure trending NNE–SSW. The AIF crosses the Alboran Ridge and connects to the transtensive Nekor Basin and the Nekor Fault to the south. In the Moroccan shelf and at the edge of a submerged volcano we dated the inception of the local subsidence at 1.81–1.12 Ma. The subsidence marks the propagation of the AIF toward the Nekor Basin. Pliocene thrusts and folds and Quaternary transtension appear at first sight to act at different tectonic periods but reflect the long-term evolution of a transpressive system. Despite the constant direction of Africa–Eurasia convergence since 6 Ma, along the southern margin of the Alboran Basin, the Pliocene–Quaternary compression evolves from transpressive to transtensive along the AIF and the Nekor Basin. This system reflects the logical evolution of the deformation of the Alboran Basin under the indentation of the African lithosphere.

scholarly journals The Mediterranean Outflow in the Strait of Gibraltar and its connection with upstream conditions in the Alborán Sea

2016 ◽  
Author(s):  
Jesús García-Lafuente ◽  
Cristina Naranjo ◽  
Simone Sammartino ◽  
José C. Sánchez-Garrido ◽  
Javier Delgado
Keyword(s):  
Potential Temperature ◽  
Western Mediterranean ◽  
Altimetry Data ◽  
Alboran Sea ◽  
Strait Of Gibraltar ◽  
Mediterranean Outflow ◽  
Alboran Basin ◽  
In Situ Observations ◽  
Alborán Sea

Abstract. The present study addresses the hypothesis that the Western Alborán Gyre in the Alborán Sea (the westernmost Mediterranean basin adjacent to the Strait of Gibraltar) influences the composition of the outflow through the Strait of Gibraltar. The process invoked is that strong and well-developed gyres help to evacuate the Western Mediterranean Deep Water from the Alborán basin, thus increasing its presence in the outflow, whereas weak gyres facilitates the outflow of Levantine and other Intermediate waters. To this aim, in situ observations collected at Camarinal (the main) and Espartel (the westernmost) sills of the Strait have been analysed along with altimetry data, which were employed to obtain a proxy of the strength of the gyre. An encouraging correlation of the expected sign was observed between the time series of potential temperature at Espartel sill, which is shown to keep information on the outflow composition, and the proxy of the Western Alborán Gyre, suggesting the correctness of the hypothesis, although the weakness of the involved signals does not allow for drawing definitive conclusions.

scholarly journals A geochemical approach to reconstructing sediment dynamic and thermohaline circulation in the western Mediterranean over the last deglaciation

2020 ◽  
Author(s):  
Jose Manuel Mesa-Fernández ◽  
Francisca Martínez-Ruiz ◽  
Marta Rodrigo-Gámiz ◽  
Francisco J. Jiménez-Espejo
Keyword(s):  
Thermohaline Circulation ◽  
Western Mediterranean ◽  
Intermediate Water ◽  
Last Deglaciation ◽  
Gulf Of Cadiz ◽  
Relative Contribution ◽  
Gulf Of Cádiz ◽  
Mediterranean Outflow ◽  
Gibraltar Strait ◽  
Alboran Basin

<p>The westernmost Mediterranean basins is an exceptional and sensitive region for reconstructing past climate and oceanographic conditions. Geochemical signatures from diverse sediment records in the Alboran Sea and the Balearic basin, in particular, Ti/ca and Fe/Ca ratios, as proxies for the relative abundance of siliciclastic vs. carbonate fraction, have been investigated. These have also been compared with other previously studied records from the western Mediterranean and the Gulf of Cadiz to elucidate the mechanisms triggering the relative variations between the carbonate and siliciclastic fraction. The lithogenic fraction represents around 70% of the sediment in the Alboran basin, which mainly derived from riverine discharge and coastal erosion. Resuspension of fine sediment particles from the slope and the sea floor by bottom-water currents is a relevant process in these basin. The studied records are located between 850 m and 2400 m below the sea level, under the influence of the Western Mediterranean Deep Water (WMDW), which is restricted to a water depth below 500-600 m and to the Moroccan margin. This deep current is formed in the Gulf of Lion, when the superficial and intermediate waters sink by a density increase, and flow out the basin through the Gibraltar Strait, contributing to the Mediterranean Outflow Water (MOW) along with the Levantine Intermediate Water (LIW). The WMDW formation is enhanced during cold and arid periods. The comparison with other previously studied records, support important variations of the mechanisms triggering the relative contribution of carbonate and siliciclastic fractions during the last 20,000 yrs. The, Ti/Ca and Fe/Ca ratios increased during cold and arid periods, such as the Heinrich Event 1 (HE1) and the Younger Dryas (YD). These changes are more prominent in the Balearic basin and the eastern Alboran basin than in the western Alboran basin and the Gulf of Cadiz. Thus, we hypothesized that the increase in the Ti/Ca and Fe/Ca ratios is rather related to the enhanced WMDW production and more remobilization of fine siliciclastic sediments.</p>

scholarly journals Comparison of the crust and upper mantle structure of the Alboran and Algerian domains (Western Mediterranean): Tectonic significance

2020 ◽  
Author(s):  
Ajay Kumar ◽  
Manel Fernàndez ◽  
Jaume Vergés ◽  
Montserrat Torne ◽  
Ivone Jimenez-Munt
Keyword(s):  
Upper Mantle ◽  
Oceanic Lithosphere ◽  
Western Mediterranean ◽  
Mantle Xenoliths ◽  
Mantle Structure ◽  
Crust And Upper Mantle ◽  
Northern Margin ◽  
Upper Mantle Structure ◽  
Alboran Basin ◽  
Valencia Trough

<p>We present a comparison of the present-day crust to upper-mantle structure in the Western Mediterranean along two NW-SE oriented geo-transects in the Alboran and Algerian basins. The Alboran domain geo-transect traverses the Iberian Massif, the Betics, the Alboran Basin and ends in the northern margin of Africa between the Tell and Rif mountains. The Algerian domain geo-transect traverses the Catalan Coast Ranges, the Valencia Trough, the Balearic Promontory, the Algerian basin, the Greater Kabylies and ends in the Tell-Atlas Mountains in the northern margin of Africa. We model the thermal, density (i.e. compositional) and seismic velocity structure by integrating geophysical and geochemical dataset in a self-consistent thermodynamic framework. The crustal structure is constrained by seismic experiments and geological cross-sections, whereas seismic tomography models and mantle xenoliths constrain the upper mantle structure and composition. The Algerian Basin lithosphere shows a typical oceanic lithosphere composition, whereas the Alboran Basin lithosphere is slightly fertile. The lithospheric mantle beneath the Betics and Greater Kabylies are also fertile compared to the Iberian and African lithospheres showing the involvement of the fertile sublithosphere mantle during the later stages of subduction. In the Valencia Trough, the lithosphere is fertile in comparison to the Balearic Promontory lithosphere, which is similar to Iberian lithosphere. A lithosphere-scale thickening is observed in the Betics, and the Greater Kabylies, and thinning follows towards the Alboran and Algerian back-arc basins. Detached slabs with anomalous temperature of-320 <sup>o</sup>C, with oceanic lithosphere composition beneath the Greater Kabylies, and Iberian lithosphere composition beneath the Betics, are required to fit the geoid height. Our results impose important constraints for the geodynamic evolution models of the Western Mediterranean.</p><p>This work has been supported by SUBTETIS (PIE-201830E039) project, EU Marie Curie Initial Training Network ‘SUBITOP’ (674899-SUBITOP-H2020-MSCA-ITN-2015), the Agencia Estatal de Investigación through projects MITE (CGL2014-59516) and GeoCAM (PGC2018-095154-B-100), and the Agency for Management of University and Research Grants of Catalonia (AGAUR-2017-SGR-847).</p>

scholarly journals Plio-Quaternary tectonic evolution of the southern margin of the Alboran Basin (Western Mediterranean)

2019 ◽  
Author(s):  
Manfred Lafosse ◽  
Elia d'Acremont ◽  
Alain Rabaute ◽  
Ferran Estrada ◽  
Martin Jollivet-Castelot ◽  
...  
Keyword(s):  
Fault Zone ◽  
Western Mediterranean ◽  
Strike Slip ◽  
Term Evolution ◽  
Southern Margin ◽  
Constant Direction ◽  
Tectonic Inversion ◽  
Alboran Basin ◽  
Back Arc

Abstract. Progresses in understanding the sedimentary dynamic of the Western Alboran Basin lead us to propose a model of evolution of its tectonic inversion since the Pliocene to present-time. Extensive and strike-slip structures accommodate the Miocene back-arc extension of the Alboran Basin, but undergo progressive tectonic inversion since the Tortonian. Across the Alboran Basin, the Alboran Ridge becomes a transpressive structure accommodating the shortening. We map its southwestern termination: a Pliocene rhombic structure exhibiting series of folds and thrusts. A younger structure, the Al-Idrissi fault zone (AIF), is Pleistocene to present-day active strike-slip fault zone. This fault zone crosses the Alboran Ridge and connects southward to the transtensive Nekor Basin and the Nekor fault. In the Moroccan shelf and at the edge of a submerged volcano, we date the inception of the local shelf subsidence from the 1.81–1.12 Ma. It marks the propagation of the AIF toward the Nekor Basin. Pliocene thrusts and folds and Quaternary transtension appear at first sight as different tectonic periods but reflects the long-term evolution of a transpressive system. Despite a constant direction of Africa/Eurasia convergence since 5 Ma at the scale of the southern margin of Alboran Basin, the Pliocene-Quaternary inversion evolves from transpressive to transtensive on the AIF and the Nekor Basin. This system reflects the expected evolution of the deformation of the Alboran Basin under the indentation of the African lithosphere.

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