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Impact of Amount of Gravity-Driven Compression and Intermediate Décollement Levels on the Sigsbee Salt Canopy Formation, Gulf of Mexico

Gwenael Guerin1, Yann Philippe2, and Jacques-Antoine Dal1
1 Total E&P USA, Inc, Houston, TX
2 Total E&P, Pau, France

The main particularity of the Gulf of Mexico gravity-driven system is the presence of an important allochthonous salt canopy that was sourced from the basal salt layer by numerous salt feeders. If an essential parameter leading the canopy development is the initial salt thickness, the amount of gravity-driven shortening and the extent of the compressional domain prior to the development of the canopy are key factors as well.

Changes of horizontal displacements above the Jurassic autochthonous salt directly impact the extent of the salt canopy. This occurs at the edge of the gravity-driven complex, or where Eocene-Oligocene shaly décollement levels are present. - The Central GOM is interpreted as a broad compressional domain active from Mesozoic to Miocene and devoid of Paleogene décollement levels. The frontal fold-belts represent the visible part of this domain. As the amount of shortening increases through time in response to the development of the main depocentres uphill, many anticlines are breached and feed the allochthonous salt canopy, which today covers most of the deep-offshore area. - To the East near the edge of the main depocentres, the amount of extension and corresponding contraction is decreasing thus the canopy is less extended, forming isolated salt sheets. - In Western GOM, the canopy appears also less developed, as most of the extension and compression during Oligocene and Miocene are related to a translation above Late Eocene-Oligocene shales. Locally, the autochthonous salt is reactivated as a décollement, causing the rupture of the pre-Late Eocene section on the Texas shelf and compression in the Perdido foldbelt at the toe.