Ocorrência de metais nos sedimentos marinhos da plataforma continental entre Itacaré e Olivença (BA)

Souza, Joseína Moutinho Tavares de; Paixão, Joana Fidelis da; Nascimento, Sérgio Augusto de Morais; Barbosa, Johildo Salomão Figueirêdo; Domínguez, José Maria Landim

doi:10.5327/z0102-9800201400020005

Cited by 2 publications

(5 citation statements)

References 7 publications

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“…The seasonal precipitation variability leads to seasonal differences in the magnitude of water and suspended sediment discharge from the Doce River, which reach maximum values in January (Oliveira & Quaresma, 2017). Today, sediment discharge from the Doce River amounts to approximately 10 million tons per year (Lima et al, 2005;Souza & Knoppers, 2011).…”

Section: Climate and Geological Settingmentioning

confidence: 99%

“…On the eastern and southeastern Brazilian coast, the Doce River is associated with the highest suspended sediment discharge into the Atlantic Ocean (Lima et al, 2005;Souza & Knoppers, 2011) and is the river mouth closest to the core site. Additionally, the ratio of illite to kaolinite at the coring depth of ~2,000 m, matches that of the shelf and the Doce River itself.…”

Section: Mineral Phase Originsmentioning

confidence: 99%

“…The smaller São Mateus River, adjacent to the north (Figure 1), shares a similar illite to kaolinite ratio (Tintelnot, 1995). The nearest river with a similarly large catchment area and sediment discharge to the Doce River is the Jequitinhonha River mouthing into the South Atlantic at around 16 °S (Souza and Knoppers, 2011). This river has an illite to kaolinite signature twice as high and the illite to kaolinite ratio of the even larger São Francisco River, mouthing at ~10 °S, is over four times higher than that of the Doce River (Tintelnot, 1995).…”

Section: Mineral Phase Originsmentioning

confidence: 99%

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Spatiotemporal Discharge Variability of the Doce River in SE Brazil During MIS 6 and 5

et al. 2022

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The modern precipitation balance in southeastern (SE) Brazil is regulated by the South American summer Monsoon and threatened by global climate change. On glacial-interglacial timescales, monsoon intensity was strongly controlled by precession-forced changes in insolation. To date, relatively little is known about the spatiotemporal distribution of tropical precipitation in SE Brazil and the resulting variability of fluvial discharge on glacial-interglacial timescales. Here, we present X-ray diffraction-derived mineralogical data for the 150–70 ka period (marine isotope stage (MIS) 6 to MIS 5) from the Doce River basin. This area was sensitive to changes in monsoonal precipitation intensity due to its proximity to the South Atlantic Convergence Zone. The data, obtained from a marine sediment core (M125-55–7) close to the Doce river mouth (20°S), show pronounced changes in the Doce River suspension load’s mineralogical composition on glacial-interglacial and precessional timescales. While the ratio of silicates to carbonates displays precession-paced changes, the mineralogical composition of the carbonate-free fraction discriminates between two assemblages which strongly vary between glacial and interglacial time scales, with precession-forced variability only visible in MIS 5. The first assemblage, dominated by high contents of kaolinite and gibbsite, indicates intensified lowland erosion of mature tropical soils. The second one, characterized by higher contents of the well-ordered illite, quartz and albite, points to intensified erosion of immature soils in the upper Doce Basin. High kaolinite contents in the silicate fraction prevailed in late MIS 6 and indicate pronounced lowland soil erosion along a steepened topographic gradient. The illite-rich mineral assemblage was more abundant in MIS 5, particularly during times of high austral summer insolation, indicating strong monsoonal rainfall and intense physical erosion in the upper catchment. When the summer monsoon weakened in times of lower insolation, the mineral assemblage was dominated by kaolinite again, indicative of lower precipitation and runoff in the upper catchment and dominant lowland erosion.

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Section: Climate and Geological Settingmentioning

confidence: 99%

Section: Mineral Phase Originsmentioning

confidence: 99%

Section: Mineral Phase Originsmentioning

confidence: 99%

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Spatiotemporal Discharge Variability of the Doce River in SE Brazil During MIS 6 and 5

et al. 2022

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“…The São Francisco River forms the boundary between the states of Sergipe and Alagoas with the São Francisco Delta located roughly 320 km SSE of Recife. With 634 000 km 2 the São Francisco has a larger drainage basin than all other East Brazilian rivers combined (622 600 km 2 , Table 1, Souza & Knoppers, 2011). The São Francisco River delivers sediment offshore to the Sergipe-Alagoas Basin.…”

Section: Study Areamentioning

confidence: 99%

“…Delta plain area and shelf width in front of the river mouth were measured in Google Earth© as part of this study. The other data are derived from Oliveira et al (2012), Souza & Knoppers (2011), Patchineelam & Smoak (1999) and Martin et al (1993) Through epeirogenetic uplift and continued erosion throughout the Quaternary, the Barreiras Formation forms cliffs along the south-east Brazilian coast (Rossetti & G oes, 2009). During the Upper Pleistocene sea-level highstand (123 ka, Andrade et al, 2003), regressive wavedominated deltas formed along the Brazilian south-east coast.…”

Section: Geological History and Delta Developmentmentioning

confidence: 99%

Predicting river mouth location from delta front dip and clinoform dip in modern and ancient wave‐dominated deltas

Zimmer

Howell

2020

Sedimentology

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Wave-dominated deltas and strandplains make up the majority of the world's depositional coastlines, provide an important record of sea-level change and serve as hydrocarbon reservoirs worldwide. Satellite imagery forms a great source of data on the recent depositional history of modern deltaic systems. In the subsurface, three-dimensional seismic and well data make the three-dimensional assessment of large-scale deltaic reservoir bodies possible but struggle to resolve internal heterogeneities away from wells. To bridge this gap in characterizing deltaic sedimentation, this study combines measurements from both the shallow, high-resolution section of three-dimensional seismic data of the Eocene Halibut Delta in the Outer Moray Firth, offshore Scotland, with information from Google Earth's satellite imagery and digital elevation model on south-east Brazilian river deltas (São Francisco, Jequitinhonha, Doce and Para ıba do Sul) to present a means of predicting the location of fluvial sediment input points with respect to clinoform geometry. The key measurement for this study is the delta front and clinoform dip which has been measured at multiple locations along strike of the coastline of the examined deltas. Dip decreases away from the inferred river mouth for all deltas by 50% within 7.2 km. The river mouth location was inferred from the position of palaeo-channels visible on the delta top and coarse sediment recorded in grab samples offshore for the south-east Brazilian deltas, and from imprints of palaeo-channels on attribute maps for the Eocene Halibut Delta. In summary, this study found that delta front dip is steepest at the location of the river mouth and decreases, along with grain size, away from it. This suggests that high dip values correlate with the proximity to the channel mouth and can be used to predict fluvial channel facies in modern deltaic systems and subsurface reservoirs.

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Ocorrência de metais nos sedimentos marinhos da plataforma continental entre Itacaré e Olivença (BA)

Cited by 2 publications

References 7 publications

Spatiotemporal Discharge Variability of the Doce River in SE Brazil During MIS 6 and 5

Spatiotemporal Discharge Variability of the Doce River in SE Brazil During MIS 6 and 5

Predicting river mouth location from delta front dip and clinoform dip in modern and ancient wave‐dominated deltas

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