ABSTRACT

Depth converted structural models constrained by 3-D seismic, gravity-magnetic and paleontological data over Atwater Valley and Mississippi Canyon protraction areas are used to address the tectonic evolution and mechanism of formation of the Eastern Mississippi Fan Fold Belt (EMFFB). The EMFFB is defined by a series of ENE-WSW trending salt cored detachment and break-thrust fold structures. The pronounced ENE-WSW linear strike orientation suggests interference with deeper basement fabric related to the rift stage opening of the Gulf of Mexico basin.

The structural evolution of the EMFFB involves a complex interplay of basement geometry, salt tectonism, gravity gliding and gravity spreading related to the following four-stage evolution of the eastern Gulf of Mexico. 1) late Triassic-early Cretaceous rift phase, 2) mid-late Jurassic salt deposition, 3) Cretaceous-Oligocene early salt tectonism and gravity gliding, 4) mid Miocene-Pliocene silici-clastic progradation, gravity spreading, and formation of the EMFFB.

Timing and mechanism of formation of the EMFFB has been addressed using palinspatically restored GeoSec depth sections, graphic correlation data, and growth strats relationships within and updip of the EMFFB. The EMFFB structures were triggered by gravity spreading, that resulted in adjustment of a 'super critical wedge' which slipped forward along a salt-basement decollement. This created the frontal EMFFB by basin inversion over pre-existing basement normal faults that acted as buttresses to the sliding wedge

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