The Maricá Slump – anatomy of a Maastrichtian gravity mass flow deposit, Santos Basin

Abstract

A Maastrichtian gravitational mass transport complex (MTC) in the northern sector of the Santos Basin is revealed by tridimensional deepwater seismic data. The deposition of the Maricá MTC was conditioned by elongated depressions controlled by N-S salt diapirs.
An extensive W-E oriented salt wall to the south of the Maricá MTC worked as a barrier to the gravitational flow originated on the north-northeast shelf. Seismic sections, structural maps and seismic attributes (e.g. edge detection) allowed the identification of the main constitutive elements of proximal (proximal escarpments), translational (top and basal surfaces, lateral escarpments, coherent blocks) and distal domains (ramp and frontal thrusts). Probably, the main trigger mechanism was the sedimentary overburden caused by high sedimentary rates related to the deltaic sedimentation on the shelf. Also, gas escape is considered as a possible secondary trigger mechanism. The catastrophic character of the mass flow could be responsible for provoking later gravitational
flows resulting in the deposition of turbidity sandstones that overlay the Maricá MTC.