Diachronous salt tectonics along the Gulf of Lions margin, Western Mediterranean

Gaullier, Virginie; Vendeville, Bruno; Travan, Gaia; Sage, Françoise; Droz, L.; Lofi, Johanna

Document type :

Autre communication scientifique (congrès sans actes - poster - séminaire...): Communication dans un congrès avec actes

Title :

Diachronous salt tectonics along the Gulf of Lions margin, Western Mediterranean

Author(s) :

Gaullier, Virginie [Auteur]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Vendeville, Bruno [Auteur]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Travan, Gaia [Auteur]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Sage, Françoise [Auteur]
Droz, L. [Auteur]
Lofi, Johanna [Auteur]

Conference title :

Mediterranean Geosciences Union, MedGU-2022, 2nd Annual Meeting

City :

Marrakech

Country :

Maroc

Start date of the conference :

2022-11-27

English abstract : [en]

Some of the world’s most spectacular salt structures are located along salt-bearing conti-nental margins which large amount of prograding sediments. The structural style includes extensional, diapiric and contractional ...
Show more >Some of the world’s most spectacular salt structures are located along salt-bearing conti-nental margins which large amount of prograding sediments. The structural style includes extensional, diapiric and contractional features, which implies significant amount of along-slope displacement. Contractional structures are typically found along the continen-tal lower slope and rise, whereas extensional structures are located along the upper slope and on the shelf. Around 6 Ma ago, the Mediterranean basin underwent spectacular paleo-environmental changes during the Messinian Salinity Crisis: the margins were deeply eroded in response to a sea-level drop of more than 1500 m, and thick evaporitic series were deposited in the deep basins. The Messinian mobile salt is therefore post-rift since the opening of the Liguro-Provençal basin formed during the Oligo-Aquitanian age. Plio-Quaternary tectonics in the western Mediterranean is dominated by huge thin-skinned salt tectonics with gravity spreading and/or gliding above the Messinian décollement. It is characterized by proximal extension, mid-slope translation, and distal shortening, consid-ered as coeval. The distal region of the western Mediterranean, especially in the Gulf of Lions, comprises circular or elongate diapirs, whose initiation was traditionally attributed to combined shortening and sediment loading. Nevertheless, re-interpretation of seismic data and analogue modelling recently showed that salt tectonics started very early in the deepest parts of the margins, immediately after deposition of the mobile salt, as is attested by lateral thickness changes and internal angular unconformities within the Messinian Upper Unit, while the Upper Unit in the upslope region remained isopach. Upslope exten-sion started well after downslope diapir growth. We therefore propose a new scenario with two main steps to explain the birth of distal salt diapirs in this area: First, salt in the deep basin was mobilized by downbuilding; second, gravity gliding started later, as has been recorded by upslope fan-shaped Early Pliocene deposits along the normal growth faults, the belt of previously-formed diapirs being reactivated by distal contraction. The tilting responsible for this late slope could be due to basin thermal subsidence, to the rapid Plio-cene re-flooding of the Mediterranean or to kinematics changes at that time in this geody-namically complex area.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Internationale

Popular science :

Non

Collections :

Laboratoire d'Océanologie et de Géosciences (LOG) - UMR 8187

Source :

Harvested from HAL

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