A Multi‐Proxy Approach to Unravel Late Pleistocene Sediment Flux and Bottom Water Conditions in the Western South Atlantic Ocean

Mathias, Grasiane L.; Roud, Sophie C.; Chiessi, Cristiano Mazur; Campos, Marília de Carvalho; Dias, Bruna Borba; Santos, Thiago Pereira dos; Albuquerque, Ana Luíza Spadano; Toledo, Felipe Antonio de Lima; Costa, Karen Badaraco; Maher, Barbara A.

doi:10.1029/2020pa004058

Cited by 14 publications

(17 citation statements)

References 107 publications

(202 reference statements)

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“…We also infer that early diagenetic effects (e.g. by changing redox conditions) (Riedinger et al, 2005) are not the main cause for the Fe/K peak in Core GeoB13861-1 at ~16 ka as it coincides remarkably well with moist conditions over SSESA implied by the sudden decrease (increase) in Al/Si (Fe/ K) of Core GL-1090 which during the deglacial was situated in a more proximal location relative to the La Plata River mouth due to the low sea level (Lantzsch et al, 2014;Mathias et al, 2021). At the same time, our ln(K/Al) and ln(Al/Si) record reveals a short intermittent dry period at 16.0 ka at the Paraıba do Sul catchment (Figures 4A, B).…”

Section: South American Low Level Jet Dynamics During the Deglaciationmentioning

confidence: 80%

“…The XRF-derived Fe/K record from Core GeoB13861-1 (38.0°S ) (Warratz et al, 2017) collected off the La Plata River mouth (Figures 1, 4M), as well as the Fe/K and Al/Si records from Core GL-1090 (24.92°S) (Mathias et al, 2021) retrieved off SE Brazil potentially show precipitation changes over SSESA, the southern part of the dipole. We updated the age model of Core GL-1090 applying the new MARINE20 calibration curve (Heaton et al, 2020) to enable a robust correlation with Core M125-35-3.…”

Section: South American Low Level Jet Dynamics During the Deglaciationmentioning

confidence: 99%

“…(H) Mg/Ca-based SST reconstruction from Core M125-35-3 (Meier et al, 2021), (I) Paixão Cave speleothem based d 18 O ‰ records and (J) Lapa Sem Fim Cave speleothem based d 18 O compilation (Strıḱis et al, 2015, 2018) from eastern South America, (K) 231 Pa/ 230 Th compilation from Core GGC5 and ODP Site 1063 representing Atlantic Meridional Overturning Circulation strength (McManusBöhm et al, 2015;Lippold et al, 2019), (L) SST Mg/Ca record of Core GeoB6211-2(Chiessi et al, 2015) collected off southern Brazil, (M) XRF-derived Fe/K from Core GeoB13861-1 close to the La Plata River mouth(Warratz et al, 2017). (N) and (O) XRF derived ln(K/Al) and Fe/K from Core GL-1090 from the La Plata River mouth(Mathias et al, 2021). Thick lines in panels a-d and g-i indicate 3-point running average.…”

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confidence: 99%

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Coupled Oceanic and Atmospheric Controls of Deglacial Southeastern South America Precipitation and Western South Atlantic Productivity

Jaeschke¹,

Rethemeyer²,

Chiessi³

et al. 2022

Front. Mar. Sci.

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Various mechanisms were proposed as substantial drivers of (sub)tropical South American hydroclimate changes during the last deglaciation. However, the interpretation of past precipitation records from the regions affected by the South American Summer Monsoon, the dominant hydroclimatic system in (sub)tropical South America, still insufficiently consider feedbacks between oceanic and atmospheric processes evident in modern observational data. Here, we evaluate ocean-atmosphere feedbacks active in the region from 19 to 4 ka based on a multi-proxy record comprising lipid biomarker, bulk sediment elemental composition and foraminiferal geochemistry from a sediment core retrieved from the tropical western South Atlantic offshore eastern Brazil at ~22°S. Our proxy data together with existing paleoclimate records show that the consideration of large scale synoptic climatic features across South America is crucial for understanding the past spatio-temporal rainfall variability, especially during the last deglaciation. While the paleohydrological data from our study site show relatively stable precipitation across the deglaciation in the core region of the South Atlantic Convergence Zone, distinct hydroclimatic gradients developed across the continent during Heinrich Stadial 1, which climaxed at ~16 ka. By then, the prevalent atmospheric and oceanic configuration caused more frequent extreme climatic events associated with positive rainfall in the northern portion of eastern South America and in the southeastern portion of the continent. These climatic extremes resulted from substantial warming of the sub(tropical) western South Atlantic sea surface that fostered oceanic moisture transport towards the continent and the reconfiguration of quasi-stationary atmospheric patterns. We further find that enhanced continental precipitation in combination with low glacial sea level strongly impacted marine ecosystems via enhanced terrigenous organic matter input in line with augmented nutrient release to the ocean. Extreme rainfall events similar to those that occurred during Heinrich Stadial 1 are likely to recur in South America as a consequence of global warming, because the projected reduction of the intra-hemispheric temperature gradient may lead to the development of atmospheric patterns similar to those in force during Heinrich Stadial 1.

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Section: South American Low Level Jet Dynamics During the Deglaciationmentioning

confidence: 80%

Section: South American Low Level Jet Dynamics During the Deglaciationmentioning

confidence: 99%

mentioning

confidence: 99%

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Coupled Oceanic and Atmospheric Controls of Deglacial Southeastern South America Precipitation and Western South Atlantic Productivity

Jaeschke¹,

Rethemeyer²,

Chiessi³

et al. 2022

Front. Mar. Sci.

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“…For example, moderate TOC availability promotes mild diagenetic iron reduction that reduces sedimentary iron so that it becomes bioavailable to MTB 116 . However, high TOC produces sulphidic diagenetic environments in which magnetite magnetofossils dissolve 154 . Equant magnetofossils dissolve more easily than bullet-shaped forms 155 , and bullet-shaped magnetofossils are more easily dissolved than hexagonal prisms and octahedral forms 153 .…”

Section: Introductionmentioning

confidence: 99%

Magnetotactic bacteria and magnetofossils: ecology, evolution and environmental implications

Goswami

et al. 2022

npj Biofilms Microbiomes

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Magnetotactic bacteria (MTB) are a group of phylogenetically diverse and morphologically varied microorganisms with a magnetoresponsive capability called magnetotaxis or microbial magnetoreception. MTB are a distinctive constituent of the microbiome of aquatic ecosystems because they use Earth’s magnetic field to align themselves in a north or south facing direction and efficiently navigate to their favored microenvironments. They have been identified worldwide from diverse aquatic and waterlogged microbiomes, including freshwater, saline, brackish and marine ecosystems, and some extreme environments. MTB play important roles in the biogeochemical cycling of iron, sulphur, phosphorus, carbon and nitrogen in nature and have been recognized from in vitro cultures to sequester heavy metals like selenium, cadmium, and tellurium, which makes them prospective candidate organisms for aquatic pollution bioremediation. The role of MTB in environmental systems is not limited to their lifespan; after death, fossil magnetosomal magnetic nanoparticles (known as magnetofossils) are a promising proxy for recording paleoenvironmental change and geomagnetic field history. Here, we summarize the ecology, evolution, and environmental function of MTB and the paleoenvironmental implications of magnetofossils in light of recent discoveries.

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“…Although various studies suggest an influence of BCC on the slope of the Brazilian Continental Margin (between 24.9° and 38°S) during glacial intervals, few use proxies linked to the plume of the La Plata River. One of these is Mathias et al (2021), which characterized the sediments of the core GL-1090 collected in the Santos Basin (24° 92´ S; 42° 51´ W; at 2,225 m of water column). From paleomagnetic, geochemical (Al/Si and Fe/K), and grain size data, they derived a characterization compatible with La Plata River plume sediment.…”

Section: Introductionmentioning

confidence: 99%

Continental influence on the fertilization of marine waters during the late quaternary in the south of the Brazilian continental margin

et al. 2022

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This study sought to understand the role of continental influence on ocean productivity along the late Quaternary based on the comparison between continental palynomorphs and paleoproductivity proxies from the marine sediment core SIS188. Retrieved from the slope of the Pelotas Basin at a depth of 1,514 m, the core documents the time interval between 47.8 and 7.4 cal ka BP, including the Marine Isotope Stages (MIS) 3, 2 and 1. The palynological content found in the core SIS188 indicates a typical flora of the southern Brazil highlands, which is at the same latitude as the core. Thus, continental input sources, such as wind-borne dust and discharges from the Mampituba and Araranguá rivers, would more likely account for the palynological content than the Brazilian Coastal Current (BCC). During the glacial intervals (MIS 3 and MIS 2), paleoproductivity (indicated by the proxies coccolith numbers, N Ratio, and TOC content) suggest the intensification of upwelling and transport of wind dust, the latter of which may have transported pollen grains to the core region. There is a concentration decrease of continental palynomorphs at the end of MIS 2, which is accentuated during MIS 1 when the sea level is higher. Paleoproductivity was high during MIS 1, especially from the Holocene onwards, although the concentration of continental-derived palynomorphs decreases sharply, showing that the rise in sea level interferes with the fertilization of marine waters far from the coast by continental input.

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A Multi‐Proxy Approach to Unravel Late Pleistocene Sediment Flux and Bottom Water Conditions in the Western South Atlantic Ocean

Abstract: Combining rock-magnetic proxies with bulk sediment characteristics has been proven useful to unravel the composition of the primary minerals present in the sediment, transport dynamics in different marine settings and sediment provenance (

Cited by 14 publications

References 107 publications

Coupled Oceanic and Atmospheric Controls of Deglacial Southeastern South America Precipitation and Western South Atlantic Productivity

Coupled Oceanic and Atmospheric Controls of Deglacial Southeastern South America Precipitation and Western South Atlantic Productivity

Magnetotactic bacteria and magnetofossils: ecology, evolution and environmental implications

Continental influence on the fertilization of marine waters during the late quaternary in the south of the Brazilian continental margin

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