Imaging the Western Mediterranean margins: a key target to understand the interaction between deep and shallow processes (WESTMED)

This is a process-oriented multidisciplinary project that integrates geological and geophysical studies to investigate the structure and evolution of the continental margins surrounding the Western Mediterranean. The coverage of available data differs noticeably from the Alboran margins (good coverage) to the South Balearic and North Algerian margins and deep basin (almost no data). Several collaborative marine and onland surveys are proposed in the frame of this project. A combined wide-angle and multichannel seismic survey, with onland data acquisition in the northern margins, is planned to unravel the structure of the crust and the uppermost mantle along selected profiles. Marine surveys based on high-resolution seismics and acoustic data acquisition will be undertaken in selected parts of the Algerian and the SE Iberian margin to investigate the sediment dynamics (turbiditic currents, depositional systems, slope instability and active tectonics) in along-strike and conjugate margins. Experimental analyses on collected offshore and onshore rock samples (from sediments to xenoliths) to determine their petrophysical and geochemical characteristics will allow for further constraints on evolutionary models. Numerical and analogue models will be developed at different scales to decipher the structure of the lithosphere and sublithospheric mantle, as well as, to reproduce the first-order driving mechanisms responsible for the present-day configuration of the region. The interaction between deep and shallow processes will be studied by integrated models relating tectonics, magmatism, vertical movements, and surface mass transport. To this end, portions of the Western Mediterranean margins will be selected as natural laboratories. Some of the proposed experiments will be done in combination with already submitted or approved projects by National Funding Agencies (MARSIBAL-Spain), (SISAL-France), and (MARADJA-France). Ship facilities and human resources will be shared within the present Collaborative Research Project.

Workshops

A EUROMARGINS MEDIATIC Workshop took place in  Barcelona, Spain, 25-27 March 2004 and was organised by Dr. Manuel Fernandez Ortiga, Group of Dynamics of the Lithosphere - GDL, Department of Geophysics and Tectonics, Institute of Earth Sciences - CSIC, Barcelona.

The main objective of the Workshop was to promote the discussion and the exchange of information among the different groups participating in any of the EUROMARGINS projects dealing with ’Rifting Processes’ and/or ’Sediment Dynamics’ as main topics of their research, and having as study areas the Western Mediterranean and/or the adjacent Atlantic margin. Therefore, the MEDIATIC Workshop call was addressed to scientists from WestMed, SWIM and MVSEIS projects with the aim of exchanging data, knowledge and experience, as well as, coordinating future surveys and activities. The Workshop focussed on those aspects related to crustal and lithospheric scale processes including tectonics, structural geology, volcanism, present-day crustal and lithospheric structure, large-scale sedimentary transport, neotectonics, seismicity and paleoseismicity. We avoided to tackle fluid related processes provided that this topic was planned to be covered in a further specific workshop held in Aveiro.

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WESTMED Presentation

The strategy of the research developed in the WEST_MED Collaborative Research Project consists in choosing different study regions in the Western Mediterranean to serve as natural laboratories where to investigate selected processes. A major added objective of the project is to study the interactions between deep- and shallow- and small- and large- scale processes.

The WEST_MED project covers topics related to sediment dynamics, rifting processes and analog and numerical modelling. Within this general framework the main activities developed during the first year of execution of the project are:

Sediment Dynamics:

Fig. 1. Developed activities relative to Sediment Dynamics and Active Tectonics within the WEST_MED project.
Fig. 1. Developed activities relative to Sediment Dynamics and Active Tectonics within the WEST_MED project.
  • High and ultra-high resolution bathymetry and geomorpholy studies performed in the Balearic Promontory, the Almeria Margin, the Palomares-Cartagena Margin, and the Algerian Margin.

  • Paleoseismicity and active tectonics studies carried out in the Algerian Margin and the Almeria Margin.

  • Sediment transport studies performed in the Almeria Margin, the Balearic Promontory and the Algerian Margin.


Rifting processes:

Fig. 2. Developed activities relative to upper crustal processes within the WEST_MED project.
Fig. 2. Developed activities relative to upper crustal processes within the WEST_MED project.
  • Paleomagnetism and structural geology studies carried out in the Betics; Alboran-Algerian basins; and the linking zone between the Betics and the Iberian chains.

  • Analysis of the sedimentary infill of the major Neogene basins of the study region (offshore and onshore).

  • Petrophysics, chemistry, isotopic and petrological analysis on rock samples from the volcanic region of Almeria (onshore).
Fig. 3. Images of the present-day crustal and lithospheric structure modelled within in the WEST_MED project.
Fig. 3. Images of the present-day crustal and lithospheric structure modelled within in the WEST_MED project.
  • Crustal structure from available seismic data and modelling of geopotential fields in the Algerian Margin and the transition from the Mediterranean to the Atlantic.
  • Lithospheric structure from modelling of geopotential fields and regional tomography data over the whole study region (Western Mediterranean)

Analog and numerical modelling (Figs. 4 and 5):

  • Large-scale geodynamic numerical and analog modelling with special emphasis to 3D delamination and subduction processes.
  • Conceptual evolutionary model of the Gibraltar Arc System based on seismic tomography data.

Cruises (Fig. 6):

  • RV Urania and RV Logachev dealing with sedimentary processes studies in the Balearic Promontory.
  • RV Le Suroit dealing with sedimentary processes and crustal structure studies in the Algerian Margin.
  • RV Logatchev to image shallow-crustal deformation of the East Alboran and northern Algerian-Balearic Basin

Main achievements:

  • Identification and detailed mapping of sea-floor bathymetry, turbiditic systems, volcanic outcrops and seamounts, fluid expulsion structures (pock-marks), and submarine slumps.
  • Identification of paleoseismic activity in fault-propagation folds and growth strata structures. Correlation between these structures and present seismic activity.
  • Tectonic controls of pre-existing structures on the Alpine deformation in the Betics-Iberian Chain-Valencia Trough-Alboran Basin system.
  • Mapping of the internal structure of the sedimentary infilling, depth-to-basement map, and crustal thickness of the Algerian Basin.
  • Neogene kinematics in the Betics inferred from paleomagnetic analyses showing distint sense rotations between Almeria and Granada regions. New results in the rotational pattern of the Gibraltar Arc.
  • Detailed crustal and lithospheric structure along several 2D profiles crossing different regions of the Western Mediterranean Margins and adjacent mainlands.
  • First approach to the 3D crustal and lithospheric structure of the Mediterranean-Atlantic transition region.
  • Regional overview of the lithosphere/upper mante structure in the Western and Central Mediterranean regions.
  • Development and application of 3D dynamic numerical codes to study Subduction Transform Edge Propagator type of faults.
  • Influences of the upper-lower mantle boundary on subductions processes and generation of poloidal-toroidal flows in the upper mantle inferred from analogue modelling.
  • Measurement of petrophysical properties and petrological and chemical characterization of granites produced by crustal anatexis.

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Project Leader:

ManuelFernández OrtigaE-Mail
CSICInstitut de Ciències de la Terra "Jaume Almera" (IJA)Departament de Geofísica i TectònicaGroup of Dynamics of the Lithosphere - GDLBarcelonaSpain

Principal Investigators:

MiquelCanals-ArtigasE-Mail
GRC Geociencies MarinesUniversitat de BarcelonaFacultat de GeologiaDepartament d'Estratigrafia, Paleontologia i Geociències MarinesBarcelonaSpain
BernardoCesareE-Mail
C.N.R. - I.G.G.Università di PadovaDipartimento di Mineralogia e PetrologiaPadovaItaly
JacquesDéverchèreE-Mail
Université de Bretagne Occidentale (UBO)Institut Universitaire Européen de la Mer (IUEM)UMR 6538 Domaines OcéaniquesPlouzanéFrance
MassimoMatteiE-Mail
University Roma Tre (UR3)Dipt. Di Scienze GeologicheRomaItaly
AlainMauffretE-Mail
University Pierre et Marie CurieLaboratoire TectoniqueParisFrance
MenchuComas MinondoE-Mail
CSICUniversidad de GranadaFacultad de CienciasInstituto Andaluz de Ciencias de la Tierra, CSICGranadaSpain
Randell A.StephensonE-Mail
Vrije UniversiteitInstitute of Earth SciencesDepartment of TectonicsAmsterdamNetherlands
MarinusWortelE-Mail
University of UtrechtFaculty of GeosciencesDepartment of Earth SciencesUtrechtNetherlands
TimothyRestonE-Mail
GEOMAR Research Centre for Marine GeosciencesChristian-Albrechts UniversityKielGermany