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ISTeP - UMR 7193
Institut des Sciences de la Terre de Paris

Séminaire ISTeP - Mickael Nirrengarten

(Université de Cergy)

Integration of hyper-extended rift deformation in the southern North Atlantic plate reconstruction

Plate modeling aims to perform palinspatic fits of the continental blocks and to restore their motion through time using geophysical data such as oceanic magnetic anomalies. This method therefore supposes a continuous motion between the full fit position and the position determined by the first oceanic magnetic anomaly. However, this stage corresponds to the rifting. Indeed, hyper-extended rifted margins are wide domains (sometimes over 100km wide) resulting from complex deformation processes which last over long period. Therefore, we propose to investigate a restoration methodology which permits to integrate the spatio-temporal rift evolution in a plate modelling. Our natural laboratory are the southern North Atlantic magma poor rifted margins which present an extensive dataset including deep ODP boreholes which enable good spatio-temporal calibrations.

Spatial, temporal and motion constraints are the prerequisites to perform plate modeling. Spatial constraints over all this system result from the mapping of rift domains determined by seismic interpretation and gravity inversion. The pre-deformation continental blocks are determined using domain mapping, crustal thickness resulting from gravity inversion and a constant initial thickness. The formation age of each rift domain can be determined by stratigraphic correlation or geochronologic data. However, this information is limited to drilled area or onshore exposed rift systems, therefore strong time constraints are limited to the Iberia-Newfoundland and Pyrenean systems. Transfer fault in newly created surfaces are the best motion markers.

19/01/2018, Salle Fourcade à 12h30

The careful integration of those local rift data permits to propose a new evolution model for the southern North Atlantic hyper-extended rift system. The key features are a south to north propagation of the deformation which is first segmented by transfer zone during the extension of the continental crust. However, mantle exhumation and seafloor spreading propagate in a V-shape toward North. Indeed, the integration of local geological data in plate modeling permit to propose a coherent kinematic model which is not unique but which permit to visualized rift propagation at the tectonic plate scale.

16/02/2017, Salle Fourcade à 12h30

26/01/18

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    L'ISTeP comprend 138 membres dont :

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