Changes in Water Masses in the Late Quaternary Recorded at Uruguayan Continental Slope (South Atlantic Ocean) / Mudanças Nas Massas De Água Durante O Quaternário Tardio Registadas No Talude Continental Uruguaio (Oceano Atlântico Sul)

Petró, Sandro Monticelli; Burone, Letícia

doi:10.12957/jse.2018.39156

Cited by 5 publications

(2 citation statements)

References 44 publications

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“…However, during glacial periods, the NADW becomes shallower and there is an intrusion of LCPW, which is more corrosive to CaCO 3 and thus increases dissolution and decreases preservation. This influence of southern water masses has previously been reported by several authors at depths of approximately 2,000 m in the South Atlantic (Clark et al, 2002;Rahmstorf, 2002;Curry and Oppo, 2005;Petró et al, , 2021Petró and Burone, 2018;Figueiredo et al, 2020).…”

Section: Dissolutionsupporting

confidence: 82%

Biogenic composition of calcium carbonate over the past 140,000 years: clues from a marine core in the Santos Basin

Tomazella,

Pedrão,

Quadros

et al. 2024

Ocean Coast. Res.

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component of the calcium carbonate (CaCO 3 ) cycle. This cycle influences the pH of seawater and regulates the CO 2 exchange between the ocean and the atmosphere, making it an essential factor in climate change (Millero, 1996).The primary mechanisms by which CO 2 is removed from the atmosphere are the biological pump and the storage of CaCO 3 in marine sediments and coral reefs (Volk and Hoffert, 1985;Charles This study aimed to investigate the biogenic composition of calcium carbonate (CaCO 3 ) in pelagic sediments in the Santos Basin over the past 140,000 years. The content and composition of CaCO 3 in different sediment fractions were evaluated, including the bulk sample, coarse fraction (foraminifera), medium fraction (juvenile foraminifera and fragments), and fine fraction (nannofossils), to determine the contribution of each fraction to the carbonated sediment composition. We found that variations in CaCO 3 levels were closely linked to glacial and interglacial periods, with higher values during interglacial periods and lower values during glacial periods. The main factor controlling the variation in CaCO 3 was dissolution, which was mainly linked to the influx of more corrosive southern water masses. Fluctuations in CaCO 3 levels were influenced by variations in productivity and dilution caused by terrigenous sediments. Nevertheless, it is noteworthy that both processes held a relatively minor impact compared to dissolution. Productivity primarily contributed to increased dissolution rates. During periods of low sea levels, dilution by terrigenous sediments became significant (similarly, the influence of the La Plata River plume was notable). However, due to the limited presence of riverine supply in the study area, which contributes directly to major dilution influences, fluctuations in terrigenous materials were considered of lesser magnitude than those caused by dissolution. The nannofossils were found to be the largest contributor to the total CaCO 3 composition, as they were the fraction least affected by the dissolution process. Overall, our results provide insights into the factors influencing CaCO 3 accumulation in marine sediments and can be used as a tool to determine changes between climatic cycles over time.

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Section: Dissolutionsupporting

confidence: 82%

Biogenic composition of calcium carbonate over the past 140,000 years: clues from a marine core in the Santos Basin

Tomazella,

Pedrão,

Quadros

et al. 2024

Ocean Coast. Res.

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“…Supra-lysoclinal pelagic carbonate dissolution has been described from the western South Atlantic in the past, being related to changes in bottom water masses (Petró et al, 2018a;Petró and Burone, 2018;Petró et al, 2021). Nevertheless, the relation between calcium carbonate dissolution and sea surface productivity has not yet been approached in the studied area.…”

Section: Introductionmentioning

confidence: 98%

Calcium Carbonate Dissolution Triggered by High Productivity During the Last Glacial–Interglacial Interval in the Deep Western South Atlantic

et al. 2022

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Studies reconstructing surface paleoproductivity and benthic environmental conditions allow us to measure the effectiveness of the biological pump, an important mechanism in the global climate system. In order to assess surface productivity changes and their effect on the seafloor, we studied the sediment core SAT-048A, spanning 43–5 ka, recovered from the continental slope (1,542 m water depth) of the southernmost Brazilian continental margin, deep western South Atlantic. We assessed the sea surface productivity, the organic matter flux to the seafloor, and calcite dissolution effects, based on micropaleontological (benthic and planktonic foraminifers, ostracods), geochemical (benthic δ13C isotopes), and sedimentological data (carbonate and bulk sand content). Superimposed on the induced changes related to the last glacial–interglacial transition, the reconstruction indicates a significant and positive correlation between the paleoproductivity proxies and the summer insolation. From the reconstructed data, it was possible to identify high (low) surface productivity, high (low) organic matter flux to the seafloor, and high (low) dissolution rates of planktonic Foraminifera tests during the glacial (postglacial). Furthermore, within the glacial, enhanced productivity was associated with higher insolation values, explained by increased northeasterly summer winds that promoted meandering and upwelling of the nutrient-rich South Atlantic Central Water. Statistical analyses support the idea that productivity is the main cause for seafloor calcium carbonate dissolution, as opposed to changes in the Atlantic Meridional Overturning Circulation (at least for the 25–4 ka period). Further efforts must be invested in the comprehension and quantification of the total organic matter and biogenic carbonate burial during time intervals with an enhanced biological pump, aiming to better understand their individual roles.

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Calcium carbonate dissolution triggered by high productivity during the last glacial-interglacial interval at the deep western South Atlantic

Suárez-Ibarra

Frozza

Petró

et al. 2021

Preprint

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Studies reconstructing surface paleoproductivity and benthic environmental conditions allow us to measure the effectiveness of the biological pump, an important mechanism in the global climate system. In order to assess surface productivity changes and their effect on the seafloor, we studied the sediment core SAT-048A, spanning 43-5 ka, recovered from the continental slope (1,542 m water depth) of the southernmost Brazilian continental margin, deep western South Atlantic. We assessed the sea surface productivity, the organic matter flux to the seafloor, and calcite dissolution effects, based on micropaleontological (benthic and planktonic foraminifers, ostracods), geochemical (benthic δ 13 C isotopes), and sedimentological data (carbonate and bulk sand content). Superimposed on the induced changes related to the last glacial-interglacial transition, the reconstruction indicates a significant and positive correlation between the paleoproductivity proxies and the summer insolation. From the reconstructed data, it was possible to identify high (low) surface productivity, high (low) organic matter flux to the seafloor, and high (low) dissolution rates of planktonic Foraminifera tests during the glacial (postglacial). Furthermore, within the glacial, enhanced productivity was associated with higher insolation values, explained by increased northeasterly summer winds that promoted meandering and upwelling of the nutrient-rich South Atlantic Central Water. Statistical analyses support the idea that productivity is the main cause for seafloor calcium carbonate dissolution, as opposed to changes in the Atlantic Meridional Overturning Circulation (at least for the 25-4 ka period). Further efforts must be invested in the comprehension and quantification of the total organic matter and biogenic carbonate burial during time intervals with an enhanced biological pump, aiming to better understand their individual roles.

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Changes in Water Masses in the Late Quaternary Recorded at Uruguayan Continental Slope (South Atlantic Ocean) / Mudanças Nas Massas De Água Durante O Quaternário Tardio Registadas No Talude Continental Uruguaio (Oceano Atlântico Sul)

Cited by 5 publications

References 44 publications

Biogenic composition of calcium carbonate over the past 140,000 years: clues from a marine core in the Santos Basin

Biogenic composition of calcium carbonate over the past 140,000 years: clues from a marine core in the Santos Basin

Calcium Carbonate Dissolution Triggered by High Productivity During the Last Glacial–Interglacial Interval in the Deep Western South Atlantic

Calcium carbonate dissolution triggered by high productivity during the last glacial-interglacial interval at the deep western South Atlantic

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