Resizing the extension of the mesophotic “reefs” in the Brazilian Equatorial Margin using bioclastic facies and seabed morphology.

Abstract

Abstract Mesophotic reefs are rigid-bottom structures that compose an essential ecological role in the marine environment, but their knowledge is scarce compared to the shallow reefs due to diving depth limits and the high cost of geological and geophysical surveys deep ward. The uncovering of an extensive Amazon mesophotic reef system, or Great Amazon Reef System (GARS), in parallel to the discoveries of expressive oil and gas reservoirs in this region, became an essential discussion about marine heritage protection and mineral resource exploitation. Based on an unprecedented dataset reunion (962,338 depth points, 5,515 sampling stations and 384 seismic reflection lines), this paper presented a more accurate and realistic mapping of the mesophotic reefs over the Brazilian Equatorial Margin continental shelf. With an area of 13,478km², the carbonate facies (Bioclastic gravels) represented only 4,2% of the shelf. The results indicate that the GARS, a much smaller area than previously predicted, would correspond to a small portion of a Great Brazilian Mesophotic Bioconstruction Province (GBMBP).