Workshop "Marginal plateaus : from magmatic divergent margins to transform margins, and from the continental shelf to the pelagic and contouritic setting"

***Grenoble (France) - November 28-29th, 2017

– Keywords
magmatic divergent margins, transform margins, post-rift subsidence, contourites

– Synopsis
Marginal plateaus can be defined in the submarine morphology as flat (sub-horizontal) but deep (deeper than the shelf break) domains within the continental slope (Mercier de Lépinay et al., 2016). They occur in all passive margins, but are mainly located at the junction between diachroneous ocean basins.

These structures were classically considered as remnants of rifted margins, underlain by a thinned continental crust. However, they appear closely related to magmatic rifted margins and Seaward Dipping Reflectors. They are also systematically bounded by a transform margin. Forming prominent salients along the continental margin, they influence the deep-sea circulation, leading to contouritic sedimentation.

Both the polyphased tectonic and subsidence evolution, and the sedimentary setting controlled by deep currents, make the marginal plateaus a specific target for continental margin understanding and hydrocarbon exploration.

Based on recent data acquisition (e.g. Demerara plateau offshore French Guiana and Suriname), the aims of the workshop are to compare the numerous marginal plateaus in the world, and to bring together specialists from different Earth science fields, in order to investigate :

The nature of the basement (thinned continental crust, magmatic crust) and how it was deformed or emplaced,
The relationships between marginal plateaus, hot spots and magmatic divergent margins,
The structure of transform margins that are associated with marginal plateaus,
The control of inherited structures on the polyphased evolution of those domains,
The evolution of subsidence (and uplift), from the initial magmatic rifting to the secondary rift stage and transform opening, and, finally, to the post-rift sag stage,
The influence of the topography of marginal plateaus on the local and global circulation of intermediate and deep oceanic waters,
The specific sedimentary systems that develop in those deep-current dominated settings.

– Program
Tuesday November 28th, Amphi Kilian, ISTerre
9h Welcome
9h25 Christophe Basile Introduction and practical informations
9h30 Lies Loncke University of Perpignan Marginal plateaus : definition and scientific challenges Presentation to download
10h15 Asbjorn Breivik University of Oslo Why is the Vøring Plateau a plateau ? Presentation to download
11h00 coffee break
11h20 Gavin Elliott Lukoil An overview of the Hatton-Rockall plateau
12h05 Dave McCarthy British Geological Survey The Falkland plateau
12h50 lunch
14h00 Walter Roest Ifremer An overview of the scientific exploration of the Demerara  plateau Presentation to download
14h45 Thomas Museur University of Brest Deep structure of the Demerara marginal plateau from MARGATS cruise academic wide-angle and multi-channel seismics, insights on the origin of the plateau Presentation to download
15h30 coffee break
15h50 Christophe Basile University Grenoble-Alpes Where was the CAMP hotspot, and how it controlled the opening of the Central and Equatorial Atlantic oceans around the Demerara plateau ?
16h35 Nicolas Coltice University of Lyon Thermal fluctuations beneath continents Presentation to download
17h20 Discussion

Wednesday November 29th, Amphi Kilian, ISTerre
8h45 François Chauvet Sedisor Recent concepts on volcanic passive margins
9h30 Scott Bryan Queensland University of Technology Large ignous provinces, continental break-up and marginal plateaus Presentation to download
10h15 coffee break
10h35 Christophe Basile University Grenoble-Alpes Transform margins along marginal plateaus Presentation to download
11h20 Thierry Dumont CNRS The Briançonnais fossil marginal plateau, Western Alps : identification of the early stages of inversion and implications for its restoration Presentation to download
12h05 lunch
13h15 Javier Hernandez-Molina Royal Holloway University Contourite terraces  vs marginal platforms : conceptual implications Presentation to download
14h00 Anne Sophie Fanget University of Perpignan The Demerara Plateau : a case study of the initiation and evolution of a contourite depositional system on a marginal plateau
14h45 Final discussion
16h00 End of meeting

Posters
Frédérique Eynaud et al. University of Bordeaux The Bay of Biscay and the Capbreton canyon as key sedimentary contexts to decipher Holocene sea-surface hydrography of the boreal Atlantic Poster to download
Estefania Llave et al. Instituto Geológico y Minero de España From marginal platforms to contourite terraces : a study case from NW Iberia
Walter Roest et al. Ifremer Multidisciplinary scientific program of investigation of the structure and evolution of the Demerara marginal plateau
David Graindorge et al. University of Brest The enigmatic deep structure and margins of the Demerara Plateau : the MARGATS cruise seismic data together with dredges,kinematic reconstructions and magnetic data reveal a complex and polyphased magmatic history
Igor Girault et al. University Grenoble-Alpes The outcropping basement of the Demerara marginal plateau (French Guiana-Surinam) : results from DRADEM dredges
Lies Loncke et al. University of Perpignan The Demerara marginal plateau : a case study of a distal marginal plateau dominated by contouritic processes and gravity instability
Cédric Tallobre et al. Université du Littoral – Côte d’Opale Formation and evolution of a glauconite-rich contourite depositional system on the marginal Demerara plateau (French Guiana, Surinam)

– Practical information
The workshop will be held in english.
Location and date : Grenoble (France), November 28-29th 2017
All presentations are in Amphi Kilian, ISTerre, 1381 rue de la Piscine

– Contact
Mail : christophe.basile univ-grenoble-alpes.fr
Tel : +334 76 51 40 69
Adress : ISTerre, 1381 rue de la Piscine
Université Grenoble-Alpes
38400 St Martin d’Hères – France

– The organization committee
Christophe Basile (ISTerre, Université Grenoble-Alpes)
Lies Loncke (CEPHREM, University Perpignan)
Walter Roest (IFREMER, Brest)
David Graindorge (University Brest)

– Sponsors