Salt morphologies and crustal segmentation relationship: New insights from the Western Mediterranean Sea

Massimo Bellucci (1, 2, 3) , Daniel Aslanian (1) , Maryline Moulin (1) , Marina Rabineau (2) , Estelle Leroux (1) , Romain Pellen (1) , Jeffrey Poort (4) , Anna del Ben (3) , Christian Gorini (4) , Angelo Camerlenghi (5)

1 GM - Unité Géosciences Marines
2 LGO - Laboratoire Géosciences Océan
3 Dipartimento di Matematica e Geoscienze [Trieste]
4 iSTeP - Institut des Sciences de la Terre de Paris
5 OGS - Istituto Nazionale di Oceanografia e di Geofisica Sperimentale

Salt tectonics at salt-bearing margins is often interpreted as the combination of gravity spreading and gravity gliding, mainly driven by differential sedimentary loading and margin tilting, respectively. Nevertheless, in the Western Mediterranean Sea, the classical salt-tectonic models are incoherent with its morpho-structural setting: Messinian salt was deposited in a closed system formed several Ma before the deposition, horizontally throughout the entire deep basin, above a homogenous multi-kilometer pre-Messinian thickness. The subsidence is purely vertical in the deep basin, implying a regional constant initial salt thickness. The post-salt overburden is homogenous and the distal salt deformation occurred before the mid-lower slope normal-fault activation. Instead, the compilation of MCS and wide-angle seismic data highlighted a clear coincidence between crustal segmentation and salt morphology domains. The salt structures change morphology at the boundary between different crustal natures. Regional thermal anomalies and/or fluid escapes, associated with the exhumation phase, or mantle-heat segmentation, could therefore play a role in adding a further component to the already known salt-tectonics mechanisms. The compilation of crustal segmentation and salt morphologies in different salt-bearing margins, such as the Santos, Angolan, Gulf of Mexico and Morocco-Nova Scotia margins, seems to depict the same coincidence. In view of the evidences observed in the Western Mediterranean Sea, the influence of the temperature parameter on salt deformation should not be overlooked and warrants further investigation.

Mots clés: Salt tectonics; Passive margin; Western Mediterranean Sea; Thermicity; Messinian Salinity Crisis

Domaines: Océanographie; Stratigraphie; Tectonique

Massimo Bellucci, Daniel Aslanian, Maryline Moulin, Marina Rabineau, Estelle Leroux, et al.. Salt morphologies and crustal segmentation relationship: New insights from the Western Mediterranean Sea. Earth-Science Reviews, 2021, 222, pp.103818. ⟨10.1016/j.earscirev.2021.103818⟩. ⟨hal-03401203⟩