Cours ABG Marges passives

Structure of non-volcanic vs volcanic marginsOcean. cr. C.O.B.Stretched Cont. cr.Ocean. cr.igneous crust.Cont. cr.13Master1 BGAE Spécialité Géosciences Architecture des Bassins & Géomatique 2008 - Michel SéranneFormation of volcanic marginsMantle fusion (lithosph + asthenosph)Upwelling of asthenosphereLarge lava flows (traps)Dike intrusion in Cont. Cr.Emplacement of grabbro bodies atMoho = underplatingBreak-up : accretion of oceanic crustAfter break-up : differential subsidence=> Seaward dipping lava flowActive rifting => volcanic marginsubsidence14Master1 BGAE Spécialité Géosciences Architecture des Bassins & Géomatique 2008 - Michel Séranne©NOAAParanaBasalticTrapsVolcanic vs non-volcanic marginsmid-Atlantic ridgeTristan da CunhaHot-spotWalvis RidgeAngolaNamibie15Master1 BGAE Spécialité Géosciences Architecture des Bassins & Géomatique 2008 - Michel SéranneLIP’s: basalt plateaus = trapsAssociated with volcanic margins(e.g. Atlantic volcanic M.)Large Igneous ProvincesPlume = convection => decompression => mantle fusion16Master1 BGAE Spécialité Géosciences Architecture des Bassins & Géomatique 2008 - Michel Séranne4