Abstract:ABSTRACT. Seismic sections on the continental shelf adjacent to Araruama lagoon, Rio de Janeiro state, allowed the mapping of the acoustic basement and the seismic analysis of the sedimentary cover until the middle continental shelf (∼ 110 m). The acoustic basement outcrops in the northwest sector of the study area, while it is buried under 200 m of the sediments in the southeast sector (middle shelf). Four seismic sequences (SI, SII, SIII and SIV) limited by four unconformities (DI, DII, DIII and DIV) were id… Show more
“…INHG: Initiation of Norther Hemisphere Glaciations, MPT: Mid-Pleistocene Transition; MBE : Mid Brunhes Event; MIS Marine Isotopic Stage. The relationship between Late Quaternary margins' stratigraphy and sea level changes is well-documented from high resolution seismic data over the world, especially for the last few 100 kacycles (e.g., Kolla et al, 2000;Schuur Duncan et al, 2000;Liu et al, 2004;Rabineau et al, 2005Rabineau et al, , 2006Berne et al, 2007;Ridente et al, 2008;Bassetti et al, 2008;Tesson et al, 2010;Le Roy et al, 2014;Lafosse et al, 2018). Several studies have been conducted on the continental shelf of Rio de Janeiro State (e.g., Pinheiro-Moreira et al, 2001;Artusi et al, 2007;Fleming et al, 2009;Maia et al, 2010;Reis et al, 2013) and suggested that the continental shelf of the Santos Basin also offers the opportunity to examine the relationship between the architecture of the Quaternary deposits and the 100 ka glacio-eustatic cycles. However, all these studies focused on the continental shelf and could not describe the evolution of the sedimentary bodies towards the basin.…”
“…INHG: Initiation of Norther Hemisphere Glaciations, MPT: Mid-Pleistocene Transition; MBE : Mid Brunhes Event; MIS Marine Isotopic Stage. The relationship between Late Quaternary margins' stratigraphy and sea level changes is well-documented from high resolution seismic data over the world, especially for the last few 100 kacycles (e.g., Kolla et al, 2000;Schuur Duncan et al, 2000;Liu et al, 2004;Rabineau et al, 2005Rabineau et al, , 2006Berne et al, 2007;Ridente et al, 2008;Bassetti et al, 2008;Tesson et al, 2010;Le Roy et al, 2014;Lafosse et al, 2018). Several studies have been conducted on the continental shelf of Rio de Janeiro State (e.g., Pinheiro-Moreira et al, 2001;Artusi et al, 2007;Fleming et al, 2009;Maia et al, 2010;Reis et al, 2013) and suggested that the continental shelf of the Santos Basin also offers the opportunity to examine the relationship between the architecture of the Quaternary deposits and the 100 ka glacio-eustatic cycles. However, all these studies focused on the continental shelf and could not describe the evolution of the sedimentary bodies towards the basin.…”
“…Most of the studies dealing with the Quaternary section have focused on the shelf morphology, superficial or subsurface sediment distribution or on the geomorphology and stratigraphic evolution of coastal features, like bays, coastal plains and the shallow shelf environments during the Holocene (e.g. COSTA, 1979;MAIA et al, 1984;MUEHE, 1989;MUEHE;CARVALHO, 1993;MUEHE;VALENTINI, 1998;TURCQ et al, 1999;MARTIN et al, 2003;ARTUSI;FIGUEIREDO, 2007;MAHIQUES et al, 2007;FLEMING et al, 2009). Therefore, the PlioQuaternary stratigraphic window remains as an important gap in the attempt to reconstruct the sedimentary history of the Santos basin continental shelf and of the Brazilian continental margin, as a whole.…”
A B S T R A C TSeismic analysis of sparker lines of GEOMAR cruises allowed us to address a first stratigraphic scenario for the shallow sedimentary record (~300 msec) of the continental shelf off Rio de Janeiro State, northern Santos basin. Two sets of seismic sequences were identified and interpreted as a succession of depositional sequences induced by repeated glacioeustatic cycles. Depositional sequences composing Set I (SqA-SqC) are dominantly sigmoidal, reflecting periods of increasing accommodation space that favoured the preservation of both aggradational and progradational units; sequences of Set II (Sq1-Sq5) are essentially seaward-thickening stacks of forced-regression wedges, implying periods of declining accommodation space. Comparison between seismic lines and chronostratigraphic data allowed the mapped sequences to be placed within the Plio-Quaternary. Correlations also suggest that most of Set I (SqA and lower portion of SqB) was deposited during the Pliocene (undifferentiated Pliocene), while the upper portion of sequence SqC and sequences of Set II (Sq1-Sq5) have been placed within the Quaternary. Correlation of chronostratigraphic data with δ 18 O isotopic "sea level curves" also supports the hypothesis that sequences Sq1-Sq4 are fourth-order forced-regression sequences that record 100-120 kyr glacioeustatic cycles for the last 440-500 kyr, while sedimentary units labeled Sq5 would represent the transgressive and highstand deposition during the Holocene.
R E S U M OA análise sísmica de dados sparker das Operações GEOMAR permitiu a elaboração de um primeiro arcabouço estratigráfico da seção rasa (~300 msec) da plataforma continental do Estado do Rio de Janeiro, norte da bacia de Santos. Dois conjuntos de seqüências sísmicas foram interpretados como seqüências deposicionais induzidas por oscilações glacio-eustáticas. O Conjunto I (SqA-SqC), composto por seqüências dominantemente sigmoidais, reflete condições de geração de espaço de acomodação sedimentar capaz de preservar seus componentes agradacionais-progradacionais; o Conjunto II (Sq1-Sq5), composto principalmente por prismas de regressão forçada, indica diminuição relativa de espaço de acomodação. Dados cronoestratigráficos de poços permitiram posicionar a seção sísmica investigada na janela plio-quaternária: à maior parte do Conjunto I (SqA e parte inferior da SqB) foi atribuída uma idade Plioceno (indiferenciado); à seção estratigráfica que se estende da porção superior da SqC até o Conjunto II foi atribuída uma idade quaternária. A correlação entre a base de dados e curvas globais de variações isotópicas de δ 18 O permitiu ainda sugerir que as seqüências Sq1-Sq4 registram sequências regressivas de quarta ordem (ciclos glacio-eustáticos de cerca de 100-120 ka) durante os últimos 440-500 ka. A sequência Sq5 representaria a deposição holocênica, constituída por depósitos transgressivos e de sistemas de mar alto.
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