Geomorphological imprint of opposing ocean bottom currents, a case study from the southeastern Brazilian Atlantic margin

Author(s)

de Mahiques, M. M. ^{[1, 2]} ; Lobo, F. J. ^[3] ; Schattner, U. ^[4] ; Lopez-Quiros, A. ^[3] ; Rocha, C. B. ^{[5, 6]} ; Dias, R. J. S. ^[1] ; Montoya-Montes, I ^{[7, 8]} ; Vieira, A. C. B. ^[1]

Affiliation

^[1] Univ Sao Paulo, Oceanog Inst, Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Energy & Environm, Sao Paulo - Brazil

^[3] CSIC Univ Granada, Inst Andaluz Ciencias Tierra, Granada - Spain

^[4] Univ Haifa, Leon H Charney Sch Marine Sci, Dr Moses Strauss Dept Marine Geosci, Haifa - Israel

^[5] Univ Connecticut, Storrs, CT - USA

^[6] Woods Hole Oceanog Inst, Falmouth, MA - USA

^[7] Univ Las Palmas Gran Canaria, Inst Oceanog & Cambio Global IOCAG, Las Palmas Gran Canaria - Spain

^[8] Inst Geol & Minero Espana, Unidad Canarias, Las Palmas Gran Canaria - Spain

• Document type: Journal article
• Source: MARINE GEOLOGY; v. 444, FEB 2022.
• Web of Science Citations: 0

Abstract

The combination of oceanographic processes and a negligible fluvial terrestrial sediment contribution makes the Santos Basin margin (southwestern Brazil) a unique environment for studying thew morphological imprint of bottom currents on the seafloor morphology. We divide the seafloor into four domains: outer shelf, upper, middle, and lower slope, based on an analysis of sub-bottom Chirp profiles, multichannel seismic data, hydro graphic data, numerical simulation outputs, and a seismic-derived bathymetry map. A clinoform at the outer shelf and upper slope, topped by erosional morphologies, developed below the SW-flowing Brazil Current (BC). At the bottom of the upper slope, a rugged and mounded surface around 600 mbsl coincides with the current flow reversal to the underlying NE-flowing Intermediate Western Boundary Current (IWBC). The smooth middle slope exhibits sheeted contourites interrupted by occasional channel-and-mound complexes. From the middle slope base, salt tectonics becomes a major player in setting the seafloor morphology. The slope-parallel Santos Channel develops above a subsurface diapir and the Cabo Frio Fault. The latter divides between the landward gap in subsurface Albian salt and the basinward rich diapir realm. Hence, the lower slope is reworked by the SW-flowing Deep Western Boundary Current (DWBC); however, salt tectonics dictates its morphology. Our study consists of a unique example for studying the morpho-sedimentary imprint of a countercurrent flowing on the continental slope and also for exploring the interaction between bottom flows with a suite of endogenic processes, such as salt tectonics, fluid flows, and mass movements. (AU)

• FAPESP's process: 14/08266-2 - Continental slope morphological features on the SE Brazilian Margin: active tectonics versus modern oceanographic conditions
• Grantee: Michel Michaelovitch de Mahiques
• Support Opportunities: Regular Research Grants
• FAPESP's process: 10/06147-5 - Increase of the research capabilities in oceanography and related sciences in São Paulo State, Brazil
• Grantee: Michel Michaelovitch de Mahiques
• Support Opportunities: Research Program on Global Climate Change - Regular Grants
• FAPESP's process: 19/06250-5 - Diapir exposure at the ocean floor as a new paleo-currents indicator: a case study from Santos Basin, offshore Brazil
• Grantee: Michel Michaelovitch de Mahiques
• Support Opportunities: Regular Research Grants
• FAPESP's process: 15/17763-2 - Mudbelts from the South and Southeast Brazil: implications about the anthropogenic influence on the marine environment
• Grantee: Márcia Caruso Bícego
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 20/03363-0 - Echofacies of the Brazil Current - intermediate western boundary current coupled system
• Grantee: Ana Carolina Barbosa Vieira
• Support Opportunities: Scholarships in Brazil - Scientific Initiation