3D Modeling of the Deep Structures of Distal Rifted Margins

The observation of anomalously high seismic velocities (with Vp > 7.1 km/s) under rifted margins is associated with the presence of deep Lower Crustal Bodies (LCBs) (Eldholm et al., 2000). In addition, the observed gravity field and combined seismic and gravity modelling studies (Hirsch et al., 2010; Maystrenko et al., 2013) along volcanic margins indicate that these LCBs also represent high-density domains. Several hypotheses can explain their lithology and emplacement: (1) mafic intrusions emplaced during the rifting and often related to Seaward Dipping Reflectors (SDRs) at the surface (Eldholm et al., 2000), (2) serpentinised mantle exhumed during the final extreme thinning of the crust, and (3) high degree metamorphic rocks inherited from a previous orogenic phase (Ebbing et al., 2006). It is a difficult task to determine the lithology and geometry of the lower crustal bodies but it is of first importance to understand their role in the development of rifted margins.