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Portilho-Ramos RC, Cruz APS, Barbosa CF, Rathburn AE, Mulitza S, Venancio IM, Schwenk T, Rühlemann C, Vidal L, Chiessi CM, Silveira CS. Methane release from the southern Brazilian margin during the last glacial. Sci Rep 2018; 8:5948. [PMID: 29654329 PMCID: PMC5899165 DOI: 10.1038/s41598-018-24420-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 03/26/2018] [Indexed: 11/09/2022] Open
Abstract
Seafloor methane release can significantly affect the global carbon cycle and climate. Appreciable quantities of methane are stored in continental margin sediments as shallow gas and hydrate deposits, and changes in pressure, temperature and/or bottom-currents can liberate significant amounts of this greenhouse gas. Understanding the spatial and temporal dynamics of marine methane deposits and their relationships to environmental change are critical for assessing past and future carbon cycle and climate change. Here we present foraminiferal stable carbon isotope and sediment mineralogy records suggesting for the first time that seafloor methane release occurred along the southern Brazilian margin during the last glacial period (40-20 cal ka BP). Our results show that shallow gas deposits on the southern Brazilian margin responded to glacial-interglacial paleoceanographic changes releasing methane due to the synergy of sea level lowstand, warmer bottom waters and vigorous bottom currents during the last glacial period. High sea level during the Holocene resulted in an upslope shift of the Brazil Current, cooling the bottom waters and reducing bottom current strength, reducing methane emissions from the southern Brazilian margin.
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Affiliation(s)
- R C Portilho-Ramos
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359, Bremen, Germany. .,Programa de Pós Graduação em Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista S/N, 24020-141, Niterói RJ, Brazil. .,Institute of Geosciences, University of São Paulo, Rua do Lago 562, 05508-080, São Paulo SP, Brazil.
| | - A P S Cruz
- Programa de Pós Graduação em Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista S/N, 24020-141, Niterói RJ, Brazil
| | - C F Barbosa
- Programa de Pós Graduação em Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista S/N, 24020-141, Niterói RJ, Brazil
| | - A E Rathburn
- Department of Geological Sciences, California State University Bakersfield, 9001 Stockdale Highway, Bakersfield, CA, USA
| | - S Mulitza
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359, Bremen, Germany
| | - I M Venancio
- Center for Weather Forecasting and Climate Studies (CPTEC), National Institute for Space Research (INPE), Cachoeira Paulista, Brazil
| | - T Schwenk
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359, Bremen, Germany
| | - C Rühlemann
- BGR - Federal Institute for Geosciences and Natural Resources, Stilleweg 2, 30655, Hannover, Germany
| | - L Vidal
- Aix-Marseille University, CNRS, IRD, CEREGE UM34, 13545, Aix-en-Provence, France
| | - C M Chiessi
- School of Arts, Sciences and Humanities, University of São Paulo, Av. Arlindo Béttio 1000, 03828-000, São Paulo SP, Brazil
| | - C S Silveira
- Programa de Pós Graduação em Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista S/N, 24020-141, Niterói RJ, Brazil
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