Vol. 70 No. Suppl. 2 (2022): Biology and Geochemistry of seabed pockmark and carbonate mound habitats
This Special Article Collection presents recent discoveries from the ongoing multidisciplinary project ‘Biology and Geochemistry of Oil and Gas Seepages, Southwest Atlantic (BIOIL)’, coordinated by IOUSP and funded by Shell Brasil Petróleo LTDA through R&D levy regulation of Agência Nacional do Petróleo, Gás Natural e Biocombustível (ANP) of the Brazilian Government. In this project, we will map and study the biological and geochemical conditions of cold seeps areas in the Brazilian southeast continental margin.
Even though seeps and associated communities are widespread on continental margins worldwide, little information is found for the eastern South American continental margin. Oil and gas seepages are especially important sites not only for geological reasons but also for deep-water marine ecosystems. The Santos Basin deep-seafloor is punctuated by a series of geomorphological features (i.e., salt diapirs and pockmarks) that attest to the presence of oil and gas in the seafloor subsurface. This suggests that natural seepage of hydrocarbon fluids through sediments occurs throughout this margin. Pockmarks are formed by the escape of gases from the subsurface, tectonically conducted through salt diapirism. They are circular/elliptical-shaped depressions that can be over 1 km wide and 100 m deep. Light hydrocarbon fluid flow through the sediments may also build up authigenic carbonates that can further be colonized by cold-water corals, generating large carbonate mounds over geological time, normally positioned at the border of pockmarks. These depressions and mounds on the seafloor affect the benthic ecosystem in multiple ways in terms of water flow, type and amount of food availability, and sedimentation rates, where different bottom-associated communities thrive.
The objectives of this Special Article Collection are to explore new discoveries on different oceanographic perspectives of the Santos Basin seabed, integrating biological, geological, and geochemical data.
This is the Volume 70, Suppl. 2 (2022) of the Ocean and Coastal Research.
