Constraining Millennial-Scale Changes in Northern Component Water Ventilation in the Western Tropical South Atlantic

Author(s):Show less -

Campos, Marilia C. ^[1] ; Chiessi, Cristiano M. ^[1] ; Venancio, Igor M. ^[2] ; Pinho, Taina M. L. ^[3] ; Crivellari, Stefano ^[3] ; Kuhnert, Henning ^[4] ; Schmiedl, Gerhard ^[5] ; Diaz, Rut A. ^[6] ; Albuquerque, Ana Luiza S. ^[6] ; Portilho-Ramos, Rodrigo C. ^[4] ; Bahr, Andre ^[7] ; Mulitza, Stefan ^[4]

Affiliation

^[1] Univ Sao Paulo, Sch Arts Sci & Humanities, Sao Paulo - Brazil

^[2] Natl Inst Space Res INPE, Ctr Weather Forecasting & Climate Studies CPTEC, Cachoeira Paulista - Brazil

^[3] Univ Sao Paulo, Inst Geosci, Sao Paulo - Brazil

^[4] Univ Bremen, MARUM Ctr Marine Environm Sci, Bremen - Germany

^[5] Univ Hamburg, Ctr Earth Syst Res & Sustainabil, Inst Geol, Hamburg - Germany

^[6] Fluminense Fed Univ, Grad Program Geochem, Niteroi, RJ - Brazil

^[7] Heidelberg Univ, Inst Earth Sci, Heidelberg - Germany

• Document type: Journal article
• Source: PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY; v. 35, n. 7 JUL 2020.
• Web of Science Citations: 0

Abstract

Negative excursions in the stable carbon isotopic composition (delta C-13) at Atlantic intermediate to mid-depths are common features of millennial-scale events named Heinrich Stadials. The mechanisms behind these excursions are not yet fully understood, but most hypotheses agree on the central role played by the weakening of the Atlantic meridional overturning circulation. Marine records registering millennial-scale negative delta C-13 excursions in the Atlantic are mostly restricted to the Heinrich Stadials of the last deglacial, while the Heinrich Stadials of the last glacial are poorly studied. Here, we constrain changes in bottom water ventilation in the western tropical South Atlantic mid-depth during Heinrich Stadials of the last glacial and deglacial by investigating marine core M125-95-3. The concurrent decreases in benthic foraminifera delta C-13 and increases in bulk sediment sulfur indicate an increased Northern Component Water (NCW) residence time in the western tropical South Atlantic mid-depth during Heinrich Stadials. Furthermore, a coherent meridional pattern emerges from the comparison of our new data to previously published mid-depth records from the western South Atlantic. While our record shows the largest negative delta C-13 excursions during almost all Heinrich Stadials, the western equatorialAtlantic showed medium and the subtropical South Atlantic showed the smallest negative excursions. This meridional pattern supports the notion that during Heinrich Stadials, a reduction in the NCW delta C-13 source signal together with the accumulation of respired carbon at NCW depths drove the negative delta C-13 excursions. We suggest that the negative delta C-13 excursions progressively increase along the NCW southwards pathway until the signal dissipates/dilutes by mixing with Southern Component Water. (AU)

• FAPESP's process: 16/10242-0 - Occurrence and impact of the mega-South Atlantic Convergence Zone over the eastern South America during the last glacial period: a paleoceanographic approach
• Grantee: Marília de Carvalho Campos Garcia
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 19/10642-6 - Response of the upper water column at the origin of the Brazil Current to slowdown events of the Atlantic Meridional Ocean Circulation during the last 80 ka
• Grantee: Tainã Marcos Lima Pinho
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 18/06790-7 - Variability of the Brazil Current and South American climate during the last glacial cycle: assessing sea-surface temperatures via Mg/Ca analyses and pulses of terrigenous sediments via X-ray fluorescence analyses
• Grantee: Marília de Carvalho Campos Garcia
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 18/15123-4 - Past perspectives on tipping elements of the climate system: the Amazon Rainforest and the Atlantic Meridional Overturning Circulation (PPTEAM)
• Grantee: Cristiano Mazur Chiessi
• Support Opportunities: Research Grants - Research Program on Global Climate Change - Young Investigators - Phase 2