Holocene paleoreconstruction of the southwestern Atlantic ocean: a multiproxy approach of the paleoclimatic, paleoceanography and paleotemperature variability

Detalhes bibliográficos
Autor(a) principal: Santos, Felipe Rodrigues dos
Data de Publicação: 2024
Tipo de documento: Tese
Idioma: eng
Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
Texto Completo: https://www.teses.usp.br/teses/disponiveis/21/21137/tde-29072024-150521/
Resumo: The Holocene period exhibited crucial climatic features that facilitated the expansion and advancement of human civilization. Many siliciclastic continental margins have specific bathymetric and depositional characteristics that cause the formation of mud deposits that provide sedimentary records capable of recording climatic and oceanographic variations over geological periods. An understanding of the mechanisms behind climate fluctuations and the identification of cyclical events in the geological archives from this era can provide insights into the sensitivity, frequency, and likelihood of future climate change at local, regional, and global scales. To study the paleoenvironmental variations in the southern Brazilian continental shelf, two high-resolution sediment records (#557: 33.79°S - 52.21°W 61m depth, #561: 33.27°S - 51.3°W 90 m depth) were used in association with sedimentological, elemental, isotopic and molecular proxies (grain-size, total organic carbon, δ13C, n-alkanes, alkenones, and δ13C-alkanes) to reconstruct the paleoclimate, paleoceanography, and paleotemperature variations throughout the Holocene, understanding the respective forcing mechanisms that has triggered SST variations in the Southwestern Atlantic Ocean (Chapter 2) as well as the input, transport, and deposition dynamic of terrigenous material, shifts in vegetation, and variations in hydrological patterns (Chapter 3). The SST-UK37 variations in our records can be attributed to the interaction between the warm, salty, and nutrient-poor Subtropical Surface Water (STSW) and the cold, fresh, and nutrient-rich Subantarctic Surface Water (SASW). In the early Holocene, the rise in relative sea level (RSL) and the movement of the northern boundary of the subtropical westerly winds (SWW) were the primary factors influencing the latitudinal variation of the Subtropical Shelf Front (STSF). Once the relative sea level (RSL) stabilized around 5000 cal BP, the northward movement of the Plata Plume Water (PPW) became a noticeable characteristic of sedimentation and circulation in the inner shelf of southeast South America. This movement directly affected the dynamics of ΣC37Alk and SST-UK37. The RSL rise in the early Holocene is also the primary factor influencing the sedimentary organic matter. This is accompanied by a notably weaker South American Monsoon System (SAMS) and reduced precipitation over the La Plata River (LPR) region, with the terrigenous organic material in this period originating from both the LPR and small rivers from the neighboring continent. During the mid-Holocene, a higher RSL caused a trapping of sediments LPR estuary resulting in a low accumulation of terrigenous material in the southern Brazilian shelf. From 6000 cal yrs BP, a shift in the local origin of terrigenous organic matter coincides with a decrease in RSL and an influence of Plata Plume Water (PPW) in the region. During the late Holocene, with a stabilized RSL, the highest levels of southern summer insolation occurred, an increase in the South American Monsoon System (SAMS) and the establishment of El Niño-Southern Oscillation (ENSO), a greater rainfall regime was established in southeastern South America, noticeable at 4000 cal yrs BP and intensified after 2000 cal yrs BP.
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spelling Holocene paleoreconstruction of the southwestern Atlantic ocean: a multiproxy approach of the paleoclimatic, paleoceanography and paleotemperature variabilityPaleoreconstrução holocênica do Oceano Atlântico Sudoeste: uma abordagem multiproxy da variabilidade paleoclimática, paleoceanográfica e de paleotemperaturaδ13C-alcanosδ13C-alcanosAlcanosAlkanes; AlkenonesAlquenonasBiomarcadores lipídicosLipid biomarkersPlataforma Continental Sul do BrasilSouthern Brazilian Continental ShelfThe Holocene period exhibited crucial climatic features that facilitated the expansion and advancement of human civilization. Many siliciclastic continental margins have specific bathymetric and depositional characteristics that cause the formation of mud deposits that provide sedimentary records capable of recording climatic and oceanographic variations over geological periods. An understanding of the mechanisms behind climate fluctuations and the identification of cyclical events in the geological archives from this era can provide insights into the sensitivity, frequency, and likelihood of future climate change at local, regional, and global scales. To study the paleoenvironmental variations in the southern Brazilian continental shelf, two high-resolution sediment records (#557: 33.79°S - 52.21°W 61m depth, #561: 33.27°S - 51.3°W 90 m depth) were used in association with sedimentological, elemental, isotopic and molecular proxies (grain-size, total organic carbon, δ13C, n-alkanes, alkenones, and δ13C-alkanes) to reconstruct the paleoclimate, paleoceanography, and paleotemperature variations throughout the Holocene, understanding the respective forcing mechanisms that has triggered SST variations in the Southwestern Atlantic Ocean (Chapter 2) as well as the input, transport, and deposition dynamic of terrigenous material, shifts in vegetation, and variations in hydrological patterns (Chapter 3). The SST-UK37 variations in our records can be attributed to the interaction between the warm, salty, and nutrient-poor Subtropical Surface Water (STSW) and the cold, fresh, and nutrient-rich Subantarctic Surface Water (SASW). In the early Holocene, the rise in relative sea level (RSL) and the movement of the northern boundary of the subtropical westerly winds (SWW) were the primary factors influencing the latitudinal variation of the Subtropical Shelf Front (STSF). Once the relative sea level (RSL) stabilized around 5000 cal BP, the northward movement of the Plata Plume Water (PPW) became a noticeable characteristic of sedimentation and circulation in the inner shelf of southeast South America. This movement directly affected the dynamics of ΣC37Alk and SST-UK37. The RSL rise in the early Holocene is also the primary factor influencing the sedimentary organic matter. This is accompanied by a notably weaker South American Monsoon System (SAMS) and reduced precipitation over the La Plata River (LPR) region, with the terrigenous organic material in this period originating from both the LPR and small rivers from the neighboring continent. During the mid-Holocene, a higher RSL caused a trapping of sediments LPR estuary resulting in a low accumulation of terrigenous material in the southern Brazilian shelf. From 6000 cal yrs BP, a shift in the local origin of terrigenous organic matter coincides with a decrease in RSL and an influence of Plata Plume Water (PPW) in the region. During the late Holocene, with a stabilized RSL, the highest levels of southern summer insolation occurred, an increase in the South American Monsoon System (SAMS) and the establishment of El Niño-Southern Oscillation (ENSO), a greater rainfall regime was established in southeastern South America, noticeable at 4000 cal yrs BP and intensified after 2000 cal yrs BP.O período do Holoceno exibiu características climáticas cruciais que facilitaram a expansão e o avanço da civilização humana. Muitas margens continentais siliciclásticas apresentam características batimétricas e deposicionais específicas que provocam a formação de depósitos de lama que fornecem registros sedimentares capazes de registrar variações climáticas e oceanográficas ao longo de periodos geologicos. A compreensão dos mecanismos que influenciaram as flutuações climáticas e a identificação de eventos cíclicos nos arquivos geológicos desta época pode fornecer informações sobre a sensibilidade, frequência e probabilidade de futuras alterações climáticas em escala local, regional e global. Para estudar as variações paleoambientais na plataforma continental sul brasileira, foram utilizados dois registros sedimentares de alta resolução em associação com proxies sedimentológicos, elementares, isotópicos e moleculares (tamanho de grão, carbono orgânico total, δ13C, n-alcanos, alquenonas e δ13C-alcanos) para reconstruir o paleoclima, paleoceanografia e variações de paleotemperatura ao longo do Holoceno, buscando entender os respectivos mecanismos de forçamento que desencadeou variações de temperatura de superficie do mar (TSM) no Sudoeste do Oceano Atlântico (Capítulo 2), bem como a dinâmica de entrada, transporte e deposição de material terrígeno, mudanças na vegetação e variações nos padrões hidrológicos (Capítulo 3). As variações TSM em nossos registros podem ser atribuídas à interação entre a quente, salgada e pobres em nutrientes Água de Subtropical de Plataforma (ASP) e a frias, frescas e ricas em nutrientes Água Superficial Subantártica (ASS). Durante o Holoceno Inicial, o aumento do nível relativo do mar (NRM) e o deslocamento do limite norte dos ventos de oeste foram os principais fatores que influenciaram a variação latitudinal da Frente de Plataforma Subtropical (FPS). Uma vez que o NRM se estabilizou em torno de 5.000 cal AP, o deslocamento da pluma do Rio da Prata (RdP) tornou-se a característica mais importante de sedimentação e circulação na plataforma interna do sudeste da América do Sul. O aumento do NRM no Holoceno Inicial é também o principal fator que influencia a matéria orgânica sedimentar, acompanhado por um Sistema de Monções da Ámerica do Sul (SMAS) mais fraco e precipitação reduzida sobre a região do RdP, com o material orgânico terrígeno neste período originário tanto do RdP como de pequenos rios do continente. Durante o Holoceno médio, um NRM mais elevado causou um aprisionamento de sedimentos do estuário do RdP resultando em um baixo acúmulo de material terrígeno na plataforma sul brasileira. A partir de 6.000 anos cal AP, uma mudança na origem local da matéria orgânica terrígena coincide com uma diminuição do NRM e uma influência da pluma do RdP na região. Durante o Holoceno tardio, com um NRM estabilizado, ocorreram os maiores níveis de insolação de verão no sul, uma intensificação no SMAS e o estabelecimento do El Niño-Oscilação Sul (ENSO), indicando um periodo mais húmido sudeste da América do Sul, perceptível a partir 4.000 anos cal AP e intensificado após 2.000 anos cal AP.Biblioteca Digitais de Teses e Dissertações da USPBicego, Marcia CarusoSantos, Felipe Rodrigues dos2024-05-24info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisapplication/pdfhttps://www.teses.usp.br/teses/disponiveis/21/21137/tde-29072024-150521/reponame:Biblioteca Digital de Teses e Dissertações da USPinstname:Universidade de São Paulo (USP)instacron:USPReter o conteúdo por motivos de patente, publicação e/ou direitos autoriais.info:eu-repo/semantics/openAccesseng2024-09-25T16:00:03Zoai:teses.usp.br:tde-29072024-150521Biblioteca Digital de Teses e Dissertaçõeshttp://www.teses.usp.br/PUBhttp://www.teses.usp.br/cgi-bin/mtd2br.plvirginia@if.usp.br|| atendimento@aguia.usp.br||virginia@if.usp.bropendoar:27212024-09-25T16:00:03Biblioteca Digital de Teses e Dissertações da USP - Universidade de São Paulo (USP)false
dc.title.none.fl_str_mv Holocene paleoreconstruction of the southwestern Atlantic ocean: a multiproxy approach of the paleoclimatic, paleoceanography and paleotemperature variability
Paleoreconstrução holocênica do Oceano Atlântico Sudoeste: uma abordagem multiproxy da variabilidade paleoclimática, paleoceanográfica e de paleotemperatura
title Holocene paleoreconstruction of the southwestern Atlantic ocean: a multiproxy approach of the paleoclimatic, paleoceanography and paleotemperature variability
spellingShingle Holocene paleoreconstruction of the southwestern Atlantic ocean: a multiproxy approach of the paleoclimatic, paleoceanography and paleotemperature variability
Santos, Felipe Rodrigues dos
δ13C-alcanos
δ13C-alcanos
Alcanos
Alkanes; Alkenones
Alquenonas
Biomarcadores lipídicos
Lipid biomarkers
Plataforma Continental Sul do Brasil
Southern Brazilian Continental Shelf
title_short Holocene paleoreconstruction of the southwestern Atlantic ocean: a multiproxy approach of the paleoclimatic, paleoceanography and paleotemperature variability
title_full Holocene paleoreconstruction of the southwestern Atlantic ocean: a multiproxy approach of the paleoclimatic, paleoceanography and paleotemperature variability
title_fullStr Holocene paleoreconstruction of the southwestern Atlantic ocean: a multiproxy approach of the paleoclimatic, paleoceanography and paleotemperature variability
title_full_unstemmed Holocene paleoreconstruction of the southwestern Atlantic ocean: a multiproxy approach of the paleoclimatic, paleoceanography and paleotemperature variability
title_sort Holocene paleoreconstruction of the southwestern Atlantic ocean: a multiproxy approach of the paleoclimatic, paleoceanography and paleotemperature variability
author Santos, Felipe Rodrigues dos
author_facet Santos, Felipe Rodrigues dos
author_role author
dc.contributor.none.fl_str_mv Bicego, Marcia Caruso
dc.contributor.author.fl_str_mv Santos, Felipe Rodrigues dos
dc.subject.por.fl_str_mv δ13C-alcanos
δ13C-alcanos
Alcanos
Alkanes; Alkenones
Alquenonas
Biomarcadores lipídicos
Lipid biomarkers
Plataforma Continental Sul do Brasil
Southern Brazilian Continental Shelf
topic δ13C-alcanos
δ13C-alcanos
Alcanos
Alkanes; Alkenones
Alquenonas
Biomarcadores lipídicos
Lipid biomarkers
Plataforma Continental Sul do Brasil
Southern Brazilian Continental Shelf
description The Holocene period exhibited crucial climatic features that facilitated the expansion and advancement of human civilization. Many siliciclastic continental margins have specific bathymetric and depositional characteristics that cause the formation of mud deposits that provide sedimentary records capable of recording climatic and oceanographic variations over geological periods. An understanding of the mechanisms behind climate fluctuations and the identification of cyclical events in the geological archives from this era can provide insights into the sensitivity, frequency, and likelihood of future climate change at local, regional, and global scales. To study the paleoenvironmental variations in the southern Brazilian continental shelf, two high-resolution sediment records (#557: 33.79°S - 52.21°W 61m depth, #561: 33.27°S - 51.3°W 90 m depth) were used in association with sedimentological, elemental, isotopic and molecular proxies (grain-size, total organic carbon, δ13C, n-alkanes, alkenones, and δ13C-alkanes) to reconstruct the paleoclimate, paleoceanography, and paleotemperature variations throughout the Holocene, understanding the respective forcing mechanisms that has triggered SST variations in the Southwestern Atlantic Ocean (Chapter 2) as well as the input, transport, and deposition dynamic of terrigenous material, shifts in vegetation, and variations in hydrological patterns (Chapter 3). The SST-UK37 variations in our records can be attributed to the interaction between the warm, salty, and nutrient-poor Subtropical Surface Water (STSW) and the cold, fresh, and nutrient-rich Subantarctic Surface Water (SASW). In the early Holocene, the rise in relative sea level (RSL) and the movement of the northern boundary of the subtropical westerly winds (SWW) were the primary factors influencing the latitudinal variation of the Subtropical Shelf Front (STSF). Once the relative sea level (RSL) stabilized around 5000 cal BP, the northward movement of the Plata Plume Water (PPW) became a noticeable characteristic of sedimentation and circulation in the inner shelf of southeast South America. This movement directly affected the dynamics of ΣC37Alk and SST-UK37. The RSL rise in the early Holocene is also the primary factor influencing the sedimentary organic matter. This is accompanied by a notably weaker South American Monsoon System (SAMS) and reduced precipitation over the La Plata River (LPR) region, with the terrigenous organic material in this period originating from both the LPR and small rivers from the neighboring continent. During the mid-Holocene, a higher RSL caused a trapping of sediments LPR estuary resulting in a low accumulation of terrigenous material in the southern Brazilian shelf. From 6000 cal yrs BP, a shift in the local origin of terrigenous organic matter coincides with a decrease in RSL and an influence of Plata Plume Water (PPW) in the region. During the late Holocene, with a stabilized RSL, the highest levels of southern summer insolation occurred, an increase in the South American Monsoon System (SAMS) and the establishment of El Niño-Southern Oscillation (ENSO), a greater rainfall regime was established in southeastern South America, noticeable at 4000 cal yrs BP and intensified after 2000 cal yrs BP.
publishDate 2024
dc.date.none.fl_str_mv 2024-05-24
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dc.language.iso.fl_str_mv eng
language eng
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dc.rights.driver.fl_str_mv Reter o conteúdo por motivos de patente, publicação e/ou direitos autoriais.
info:eu-repo/semantics/openAccess
rights_invalid_str_mv Reter o conteúdo por motivos de patente, publicação e/ou direitos autoriais.
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