Articles | Volume 17, issue 5
Ocean Sci., 17, 1213–1229, 2021
https://doi.org/10.5194/os-17-1213-2021
Ocean Sci., 17, 1213–1229, 2021
https://doi.org/10.5194/os-17-1213-2021

Research article 15 Sep 2021

Research article | 15 Sep 2021

Control of oceanic circulation on sediment distribution in the southwestern Atlantic margin (23 to 55° S)

Control of oceanic circulation on sediment distribution in the southwestern Atlantic margin (23 to 55° S)
Michel Michaelovitch de Mahiques1,2, Roberto Violante3, Paula Franco-Fraguas4, Leticia Burone4, Cesar Barbedo Rocha5, Leonardo Ortega6, Rosangela Felicio dos Santos1, Bianca Sung Mi Kim1, Rubens Cesar Lopes Figueira1, and Marcia Caruso Bícego1 Michel Michaelovitch de Mahiques et al.
  • 1Oceanographic Institute of the University of São Paulo, 05508-120, São Paulo, Brazil
  • 2Institute of Energy and Environment of the University of São Paulo, 05508-010, São Paulo, Brazil
  • 3Servicio de Hidrografia Naval, C1270ABV, Buenos Aires, Argentina
  • 4Facultad de Ciencias, Universidad de La Republica, 11400 Montevideo, Uruguay
  • 5Department of Marine Sciences, University of Connecticut, Groton, CT 06340, USA
  • 6Departamento de Biología Pesquera, Dirección Nacional de Recursos Acuáticos, 11200 Montevideo, Uruguay

Correspondence: Michel Michaelovitch de Mahiques (mahiques@usp.br)

Abstract

In this study, we interpret the role played by ocean circulation in sediment distribution on the southwestern Atlantic margin using radiogenic Nd and Pb isotopes. The latitudinal trends for Pb and Nd isotopes reflect the different current systems acting on the margin. The utilization of the sediment fingerprinting method allowed us to associate the isotopic signatures with the main oceanographic features in the area. We recognized differences between Nd and Pb sources to the Argentinean shelf (carried by the flow of Subantarctic Shelf Water) and slopes (transported by deeper flows). Sediments from Antarctica extend up to the Uruguayan margin, carried by the Upper and Lower Circumpolar Deep Water. Our data confirm that, for shelf and intermediate areas (the upper 1200 m), the transfer of sediments from the Argentinean margin to the north of 35 S is limited by the Subtropical Shelf Front and the basin-wide recirculated Antarctic Intermediate Water.

On the southern Brazilian inner and middle shelf, it is possible to recognize the northward influence of the Río de la Plata sediments carried by the Plata Plume Water. Another flow responsible for sediment transport and deposition on the outer shelf and slope is the southward flow of the Brazil Current. Finally, we propose that the Brazil–Malvinas Confluence and the Santos Bifurcation act as boundaries of geochemical provinces in the area. A conceptual model of sediment sources and transport is provided for the southwestern Atlantic margin.

1 Introduction

Physical and oceanographic processes, including ocean current circulation, river discharge, marine fronts, wind patterns, and climate variability, have a crucial impact on sediment transport variability and fate (Storlazzi and Reid, 2010; Qiao et al., 2020). The southwestern Atlantic margin is located in a key region concerning global ocean circulation and is an excellent example of a complex interaction of physical forcings in the sediment variability. Hydrodynamics are strongly influenced by the Río de la Plata (RdlP) outflow, the second-largest river basin in South America (discharge estimated at 23 000 m3 s−1; Depetris and Griffin, 1968), and by the encounter of subtropical and subantarctic water masses transported by the Brazil and Malvinas currents, which is known worldwide as Brazil—Malvinas Confluence (BMC); there is also an influence by the BMC's shelf extension, the Subtropical Shelf Front (STSF). At the BMC, water masses are transported eastwards as part of the southern limb of the basin-wide Anticyclonic Atlantic Subtropical Gyre (Boebel et al., 1997; Schmid et al., 2000). Further north, the westward flow of the gyre reaches the South American margin, where it splits into two branches, forming the Santos Bifurcation (SB; Boebel et al., 1999a; Legeais et al., 2013). The southward branch of the bifurcation feeds the Brazil Current (BC), flowing south until its eastward displacement at the BMC (Schmid et al., 2000). The northward branch flows as the Intermediate Western Boundary Current (IWBC) (Legeais et al., 2013), which is an important mechanism for the transport of the Antarctic Intermediate Water towards the Northern Hemisphere (Boebel et al., 1999b).

Even though the distribution of sediments, sources, and transport along the southwestern Atlantic margin has been known since the 1950s (Teruggi, 1954; Etchichury and Remiro, 1960, 1963; Berkowsky, 1978; Kowsmann and Costa, 1979; Urien and Martins, 1979; Potter, 1984; Berkowsky, 1986) and recently deepened based on geochemical and mineralogical methods (Campos et al., 2008; de Mahiques et al., 2008; Razik et al., 2013; Nagai et al., 2014a) important issues regarding hydrological controls are still unresolved.

Radiogenic Nd and Pb isotopes are efficient tools in studying sediment transport in continental margins (Weldeab et al., 2002; Kessarkar et al., 2003; Maccali et al., 2012, 2018; Subha Anand et al., 2019). A recent synthesis of potential sources and water mass transport in the South Atlantic was provided by Beny et al. (2020). In that study, the authors combined grain size, clay mineralogy, and Nd, Pb, and Sr isotopes to propose a deepwater mass evolution for the last ca. 30 000 years in the region. The first regional characterization of Nd and Pb isotope signatures of the upper margin surface sediments in the southwest Atlantic was provided by de Mahiques et al. (2008), filling a gap for an extensive area without information about εNd signatures (Jeandel et al., 2007; Blanchet, 2019). In that work the authors (1) recognize the isotopic signatures of the sediments from the Argentinean, southern, and southeastern Brazilian margins; and (2) describe potential source areas of the sediments, such as the Andes, the basalts of the Paraná Basin, and the pre-Cambrian rocks of the Brazilian shield.

Notwithstanding, geographic gaps in information preclude a thorough understanding of the role of key hydrological features such as the STSF, BMC, and SB in the sediment distribution and the associated geochemical boundaries, which are key for paleoceanographic studies. Moreover, in another approach for sediment sources and pathways in the southwestern Atlantic margin provided by Razik et al. (2015), the authors argued for a mixed Río de la Plata–Andean origin for the upper slope sediments off southern Brazil.

In this paper, we extend the Nd and Pb dataset along the southwestern Atlantic margin and use the concept of sediment fingerprinting to deepen the role played by hydrodynamic forcing in sediment transport and deposition. The geographical distribution of the new samples presented here, covering the Argentinean margin and the Punta del Este, Pelotas, and Santos basins and covering a bathymetry range between 5 and 4066 m, allows focusing on the role of the STSF, BMC, and BS in the distribution of sediments. The results are interpreted with the aid of the output of a state-of-the-art circulation model to understand the role of oceanographic boundaries in the distribution of sediments along the area.

https://os.copernicus.org/articles/17/1213/2021/os-17-1213-2021-f01

Figure 1Location of the study area, displaying the main flows, oceanographic boundaries, and sampling stations. Thick violet line: Malvinas Current (MC); thin blue line: Subantarctic Shelf Water (SASW); thin brown line: Río de la Plata Plume (RdlPP); thick red line: Brazil Current (BC); shaded rectangles: Subtropical Shelf Front (STSF) and Brazil–Malvinas Confluence (BMC); dashed red line: Santos Bifurcation (SB) and Intermediate Western Boundary Current (IWBC). Other abbreviations: Antarctic Intermediate Water (AAIW), Upper Circumpolar Deep Water (UCDW), North Atlantic Deep Water (NADW), and Lower Circumpolar Deep Water (LCDW). Bottom scale: topography in meters.

2 Study area

The study area comprises a southwestern Atlantic margin sector from the parallels 2300 S to 5410 S, corresponding to a linear extension of about 3500 km (Fig. 1). Syntheses of the main geological and oceanographic processes can be found in Hernandez-Molina et al. (2009, 2015), Franco-Fraguas et al. (2014, 2016), Nagai et al. (2014a, b), Violante et al. (2014, 2017a), Burone et al. (2018), Piola et al. (2018), and Piola and Matano (2019), among several others.

2.1 Morphology

The southwestern Atlantic margin is a typical segmented volcanic-rifted margin, where several transverse basins are recognized (Bassetto et al., 2000; Moulin et al., 2010; Soto et al., 2011). Its origin and evolution are intrinsically related to the opening of the South Atlantic (Nürnberg and Müller, 1991), whose rifting processes first started in the Triassic (Lovecchio et al., 2020) but effectively occurred during the Jurassic and Cretaceous.

There is a general trend of narrowing the margin towards the north (Urien and Ewing, 1974; Zembruscki, 1979; Parker et al., 1996; Violante et al., 2017a). The shelf width varies from 850 km to the south to 70 km in its northernmost limit; the shelf-break depth ranges from 80 m in southern Brazil to 200 m in Uruguay (Zembruscki, 1979; Muñoz et al., 2010; Lantzsch et al., 2014). The shelf morphology is relatively flat, but sequences of scarps and terraces are recognized along the continental shelf at varying water depths (Corrêa, 1996; Parker et al., 1996; Baptista and Conti, 2009).

The continental slope presents a highly variable morphology, including contouritic terraces, channels, mounds, erosive surfaces, and sediment drifts all along the area (Duarte and Viana, 2007; Hernández-Molina et al., 2010, 2015; Preu et al., 2013) as well as canyons (Voigt et al., 2013; Bozzano et al., 2017; Franco-Fraguas et al., 2017; Violante et al., 2017b; Warratz et al., 2019). The contouritic features and submarine canyons actively interact along the margin so that mixed contouritic–gravitational erosive and depositional features are common. Mega-slides (Reis et al., 2016; Franco-Fraguas et al., 2017) and carbonate mounds (Carranza et al., 2012; Maly et al., 2019; Steinmann et al., 2020) are also present along the margin.

2.2 Sedimentary cover

The southwestern Atlantic margin is dominated by a terrigenous, siliciclastic sedimentary cover, with extensive sand sheets (Lonardi and Ewing, 1971; Frenz et al., 2003; Figueiredo and Madureira, 2004). The Argentinean and Uruguayan shelves are capped mainly by a 5 to 15 m thick post-Last Glacial Maximum transgressive sandy sheet (with decreasing thickness towards the south) composed of dominant medium to fine sands (sometimes muddy), with varying quantities of shells (more abundant in the Uruguayan shelf) and gravels (more abundant in the Patagonian shelf).

Sandy and shelly sediments are mainly relicts of coastal and inner shelf environments that evolved during Pleistocene transgressive–regressive events (Kowsmann and Costa, 1979; Urien et al., 1980; Lantzsch et al., 2014). Therefore, they are considered relict and palimpsest, whereas gravelly dominated sediments on the southern Argentinean shelf result from glaciofluvial origin. More recent works emphasize the existence of mud depocenters as potential fates of modern sediments on the southern Brazilian shelf (Nagai et al., 2014a; de Mahiques et al., 2017, 2020; Lourenço et al., 2017).

In the slope and rise, there is a prevalence of very fine sands and silty sands, resulting from exclusively submarine processes occurring across- (gravitational) and along- (contouritic) slope, together with pelagic sedimentation (Violante et al., 2010; Bozzano et al., 2011; Franco-Fraguas et al., 2016; Schattner et al., 2020). However, coarse sands and gravels occur at or near the head of submarine canyons and in contouritic channels and moats (Lonardi and Ewing, 1971; Bozzano et al., 2011; Reis et al., 2016; Franco-Fraguas et al., 2017). Razik et al. (2015) indicate increasing grain size towards coarse sands due to sediment remobilization and redistribution due to upwelling and downwelling resulting from eddies and vertical water movement generated by the slope off southern Brazil and the meandering Brazil Current.

2.3 Ocean circulation

The southwestern Atlantic margin is characterized by complex hydrography (Matano et al., 2010). It presents two main oceanographic boundaries, the Subtropical Shelf Front (STSF), as the shelf extension of the Brazil—Malvinas Confluence (BMC) (Piola et al., 2000; Severov et al., 2012), and the less-studied Santos Bifurcation (SB) (Boebel et al., 1997, 1999a). The region is also influenced by the Río de la Plata (RdlP), the second-largest hydrographic basin in South America, whose average discharge is 22 000 m3 s−1 (Framiñan and Brown, 1996). This regional circulation system experiences seasonal latitudinal shifts in response to wind regimes (Schmid et al., 2000; Piola and Matano, 2001; Piola et al., 2018).

At the BMC, centered at 37–39 S (Maamaatuaiahutapu et al., 1992), the southward-flowing Brazil Current (BC) encounters the northward-flowing Malvinas Current (MC) (Schmid and Garzoli, 2009), transporting and mixing water masses with contrasting thermohaline characteristics. The BC is a baroclinic boundary current that concentrates its main flow in the upper 500 m of water depth upstream of 28 S, carrying the Tropical Water (TW) at the surface (Emilsson, 1961; Palma et al., 2008) and the South Atlantic Central Water (SACW) at pycnoclinic levels (Emilsson, 1961; Signorini, 1978). Near the BMC, a significant fraction of the BC transport is below 500 m. The MC is a strong barotropic boundary current that advects the Subantarctic Water (SAW) near the surface (Spadone and Provost, 2009) and the Antarctic Intermediate Water (AAIW) at intermediate levels (Tomczak and Godfrey, 1994b, a).

At the BMC, water masses are transported eastwards as part of the southern limb of the basin-wide Anticyclonic Atlantic Subtropical Gyre (Boebel et al., 1997, 1999a; Schmid et al., 2000; Núñez-Riboni et al., 2005; Legeais et al., 2013). At the intermediate levels of the westward flow of the gyre, the water reaches the South American margin near 28 S, where it splits into two branches, forming the Santos Bifurcation (Boebel et al., 1999a; Legeais et al., 2013). From the bifurcation, one-quarter of the transport at 40 W flows northward along the continental slope (mainly between the 800 and 1200 m isobaths), forming the Intermediate Western Boundary Current (IWBC) (Fernandes et al., 2009; Biló et al., 2014). About three-quarters feed the BC, flowing south until its separation from the coast at the BMC (Schmid et al., 2000; Piola and Matano, 2019). This configuration leads to an overall southward flow on the outer shelf and the outer to middle slope from 28 S up to the BMC.

Concerning deep circulation, the North Atlantic Deep Water (NADW) (Sverdrup et al., 1942), transported from the Northern Hemisphere high latitudes by the Deep Western Boundary Current, occupies the region between the 2000 and 3000 m isobaths. The NADW flows between two northward-flowing branches of the Circumpolar Water (i.e., Upper and Lower Circumpolar Deep Water). The abyssal circulation (> 3500 m) is dominated by the Antarctic Bottom Water (AABW), which is partially trapped in the Argentine Basin (Tarakanov and Morozov, 2015).

Over the shelf, the extension of the BMC, known as the Subtropical Shelf Front (STSF), separates Subtropical Shelf Water (STSW, formed by the mixture of the TW and SACW) and Subantarctic Shelf Water (SASW) (Piola et al., 2000). This narrow and sharp front extends between 32 S at 50 m of water column depth and 36 S over the shelf break, and its position appears to be stable throughout the year (Piola et al., 2000; Berden et al., 2020). The main branch of the STSF is mixed with waters transported by the BC and exported offshore along with the BMC. A secondary branch is diluted with the PPW and TW and returns along the shelf (Berden et al., 2020).

At the surface, the low-salinity RdlP plume flows northward along the inner Uruguayan continental shelf during the austral winter. In the summer and during El Niño events, the plume remains off the RdlP mouth and extends along the entire upper continental margin (Piola et al., 2000, 2005; Möller et al., 2008).

3 Materials and methods

3.1 Geochemical analyses

The samples were organized in five distinct sectors in this study, corresponding to the Santos, Pelotas, and Punta del Este marginal basins, the RdlP estuary, and the Argentinean margin. Due to the small number of samples, the sediments from Argentina were not divided into the corresponding sedimentary basins (Fig. 1). Geographic coordinates and water depth of the samples are presented in the Supplement.

The results of 156 sediment samples were used as a dataset, including 83 new samples, 53 samples published in de Mahiques et al. (2008), 6 samples published in Basile et al. (1997), 8 samples published in Franco-Fraguas et al. (2016), and 3 core top samples published in Lantzsch et al. (2014). The analytical methods used in those ancillary papers are described in the original references. The new samples were collected with box corers and multiple corers in distinct surveys on board the research vessels Alpha Crucis (Brazilian margin), Miguel Oliver, Capitán Saldaña, and Sarmiento de Gamboa (Uruguayan margin). Only the superficial samples (the upper 1 cm) of each core were used in this work.

The Nd and Pb isotopic analyses of the lithogenic fraction were conducted at the Geochronological Research Centre of the University of São Paulo, Brazil.

All chemical procedures were performed in a class 10 000 clean room equipped with laminar flow hoods of class 100. All reagents were purified before use. Water was distilled and then purified on a Milli-Q system (®Millipore Corporation) (“ultrapure” water – “Type 1”). The acids were purified in sub-boiling distillers (DST-1000, ®Savillex) and sub-boiling stills (®Savillex) at low temperatures.

All of the samples were previously decarbonated with HCl. Sediment powder (70 mg) was dissolved with HF, HNO3, and HCl acids. Dissolution was done on a MARS-5 microwave oven. Both Pb and Nd were purified by the ion exchange technique. The first stage of ion exchange chromatography involves separating Pb from the other matrix elements using columns packed with anion exchange AG1-X8, 200–400 mesh (Biorad) resin. After Pb collection, the remaining solution is dried out, and the residue is retaken to separate the rare Earth elements (REEs) using RE resin (EIChroM Industries Inc.) from the bulk solution. Nd was then separated using Ln resin (EIChroM Industries Inc.).

Pb isotopic compositions were measured on a Finnigan MAT 262 mass spectrometer. Samples were loaded on Re filaments with H3PO4 and silica gel. Every single analysis consisted of 60 ratio measurements. The Pb ratios were corrected for mass fractionation of 0.13 %a.m.u.-1 based on repeated analysis of the NBS-981 standard (206Pb/204Pb= 16.893 ± 0.003, 207Pb/204Pb= 15.432 ± 0.004, and 208Pb/204Pb= 36.512 ± 0.014; n= 11), which yielded mass discrimination and fractionation corrections of 1.0024 (206Pb/204Pb), 1.0038 (207Pb/204Pb), and 1.0051 (208Pb/204Pb). The combination of these uncertainties and within-run uncertainties is typically 0.15 %–0.48 % for 206Pb/204Pb, 0.13 %–1.07 % for 207Pb/204Pb, and 0.10 %–0.45 % for 208Pb/204Pb, all at the 2σ (95 %) confidence level. The total Pb blank contribution, < 1 ng, is negligible.

The Nd analyses, here reported as εNd values, were prepared with standard methods according to the analytical procedures described by Sato et al. (1995) and Magdaleno et al. (2017), involving HF–HNO3 dissolution plus HCl cation exchange using a Teflon powder column to separate REEs. No visible solid residues were observed after dissolution. Samples with incomplete dissolution were discarded.

Nd determinations were performed on a Thermo Neptune Plus ICP-MS. Nd isotopic ratios (143Nd/144Nd) were normalized to the value of 146Nd/144Nd= 0.7219 (DePaolo, 1981) and 143Nd/144Nd= 0.512103 of the JNDi-1 standard (laboratory average of the last 12 months). Usually, a single analysis consisted of 60 measurements of Nd. The 143Nd/144Nd mean average of the JNDi standard during the analyses was 0.512095 ± 0.000007 (n= 3) and 0.512096 ± 0.000005 between July and November 2013 (n= 56). The daily average of 143Nd/144Nd of the JNDi-1 standard was 0.512101 ± 0.000002 (n= 18). The analytical blank during the analyses varied from 51 to 53 pg.

The parameter εNd was calculated as follows:

εNd=((143Nd/144Ndsample/143Nd/144NdCHUR)-1)×104, where 143Nd/144NdCHUR= 0.512638 (Jacobsen and Wasserburg, 1980).

Reproducibility analysis was made for both Pb and Nd isotopes using Buffalo River sediment (NIST-RM8704) (n= 7), with the following results.

143Nd/144Nd= 0.51203 ± 0.00001 (SD)

206Pb/204Pb= 18.846 ± 0.018 (SD)

207Pb/204Pb= 15.646 ± 0.005 (SD)

208Pb/204Pb= 38.503 ± 0.016 (SD)

Statistical analyses were performed using the software PAST (Palaeontological Statistics) version 4.05 (Hammer et al., 2001).

To recognize the distinct isotopic domains over the study area, we applied the geochemical fingerprinting procedure, similar to the approaches proposed by Walling (2013), Miller et al. (2015), and Palazon and Navas (2017). First, a Kruskal–Wallis nonparametric analysis of variance was applied for each variable, followed by a Mann–Whitney pairwise post hoc test to identify which variables presented statistically significant differences. Finally, a discriminant analysis with standardized values was used to determine the correct classification for the previously assigned groups.

3.2 The LLC2160 circulation model

To support the geochemical data distribution interpretation, we analyzed the output of the LLC2160 simulation, a global 1/24 forward run of the Massachusetts Institute of Technology General Circulation Model (MITGCM) that was spun up from Estimating the Circulation and Climate of the Ocean (ECCO). The ECCO state estimate is similar to an ocean reanalysis and assimilates millions of observations, starting in 1992. With 90 vertical levels and a horizontal resolution of about 4 km in the South American margin, the LLC2160 simulation resolves the main ocean circulation features on the continental slope and shelf of the southwestern Atlantic. Our analysis focuses on a 12-month average spanning September 2011 through August 2012. Details of the simulation, including a description of the spin-up hierarchy and forcing, are available in Chen et al. (2018).

We used annual mean fields of the LLC2160 simulation to identify two key features: the Santos Bifurcation (SB) and the Subtropical Shelf Front (STSF). The SB is recognized as the region on the continental slope where the flow within the AAIW depth range (550–1400 m) is negligible. Specifically, we search different isobaths ranging from 500 to 1500 m for the region where the AAIW flow is weaker than 0.01 m s−1. We emphasize that the SB is not a stagnation point at which the flow is zero but a shadow zone that spans nearly 100 km, wherein the intermediate flow is feeble (see the schematic SB in Fig. 1). In our discussion below, we present the mean position and the latitudinal extension of the SB as a function of depth.

To identify the mean position of the STSF, we searched for the local maximum of the potential temperature gradient, which is a very distinct feature on the northern Argentina–southern Brazil shelf. We compute the potential temperature gradients at 40 m to avoid contamination by RdlP water (e.g., Piola et al., 2008). When applied to the LLC2160 output using seasonal averages, our method yielded frontal locations consistent with those identified by applying the isothermal criteria at 40 m proposed by Piola et al. (2008). In the yearly fields, the front approximately follows the 14 C isotherm.

https://os.copernicus.org/articles/17/1213/2021/os-17-1213-2021-f02

Figure 2Box plots of the distributions of (a) εNd, (b) 206Pb/204Pb, (c) 207Pb/204Pb, and 208Pb/204Pb. Outliers are shown as dots.

Download

https://os.copernicus.org/articles/17/1213/2021/os-17-1213-2021-f03

Figure 3Latitudinal variations of (a) εNd, (b) 206Pb/204Pb, (c) 207Pb/204Pb, and 208Pb/204Pb.

Download

4 Results

The results of isotopic analyses are presented in the Supplement and summarized in the box plots shown in Fig. 2. We also present the latitudinal variation of each isotope (Fig. 3).

εNd values show a northward trend to lower radiogenic values, varying from 0.1 (Argentina) to 17.1 (Santos Basin) (Fig. 3a). The latitudinal variation of the Pb isotopes is less clear but still visible for 207Pb/204Pb and 208Pb/204Pb (Fig. 3c and d). On average, the Argentina sector presents the highest εNd values (2.1 ± 1.3) and lowest 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values (18.620 ± 0.104, 15.615 ± 0.016, and 38.520 ± 0.149, respectively). On the other hand, the Santos sector shows the lowest εNd (12.0 ± 1.1) and highest 207Pb/204Pb and 208Pb/204Pb average values (15.664 ± 0.008 and 38.909 ± 0.016, respectively). Values of 206Pb/204Pb did not show any evident latitudinal trend. For 206Pb/204Pb, the values range from 18.045 in the Punta del Este sector to 19.409 on the Santos Basin shelf. 207Pb/204Pb values range from 15.558 to 15.768 in the same areas. Finally, 208Pb/204Pb values vary from 37.986 to 39.949, also in the same sectors.

Table 1The p values of the Mann–Whitney pairwise test. Statistically significant differences are in bold.

Download Print Version | Download XLSX

From the Kruskal–Wallis analysis, we observe that except for 206Pb/204Pb, the variables show significant differences among the compartments, thus allowing us to proceed with the discriminant analysis. Furthermore, the Mann–Whitney analysis allowed us to recognize the pairwise differences among the other variables (Table 1). Finally, it is to be noted that sediments from Argentina showed statistically significant differences with all of the variables analyzed, suggesting that they are distinct from those located towards the north. On the other hand, sediments from the Río de la Plata are statistically similar to those from the Pelotas sector for all of the variables.

https://os.copernicus.org/articles/17/1213/2021/os-17-1213-2021-f04

Figure 4Scatter plot of the samples according to the first two axes generated from the discriminant analysis.

Download

The first two axes of the discriminant analysis account for 99.72 % (99.09 % for axis 1) of the total variance considering the standardized values of εNd,207Pb/204Pb, and 208Pb/204Pb (Fig. 4). It is possible to recognize that samples from Argentina are detached from the other sectors. On the other hand, samples from Pelotas Basin show a transitional character between Santos Basin on one side and, on the other side, Río de La Plata and Punta del Este Basin.

https://os.copernicus.org/articles/17/1213/2021/os-17-1213-2021-f05

Figure 5Graphical outputs of the LLC2160 focused on the Santos Bifurcation. (a) The bifurcation is identified as the white zone located around 26 S between the 800 and the 1200 m isobath. (b) The bifurcation is recognized as the zone of velocities tending to 0 cm s−1 at 26 S–44 W.

https://os.copernicus.org/articles/17/1213/2021/os-17-1213-2021-f06

Figure 6Graphical outputs of the LLC2160 focused on the Subtropical Shelf Front. (a) Variations of temperature in the zone of the front. (b) Temperature gradient; the front is recognized as the zone of maximum gradient (darker colors). (c) Vertical transect at 35 S showing the location of the Subtropical Shelf Front (STSF) as the gradient of the Subantarctic Shelf Water (deep blue) and the Subtropical Shelf Water (light green).

Graphical representations of the LLC2160 output are presented for both the Santos Bifurcation (Fig. 5) and Subtropical Shelf Front (Fig. 6). The Santos Bifurcation is identified as the maximum horizontal velocity divergence region at the AAIW level, identified in Fig. 5a close to 26 S. The visualization based on the horizontal fields is more complicated but still visible as the sector with velocities close to 0 m s−1 (Fig. 5b). The Subtropical Shelf Front (Fig. 6a) is identified as a maximum subsurface temperature gradient (Fig. 6b). Vertically it is well marked below the 30 m isobath (Fig. 6c).

https://os.copernicus.org/articles/17/1213/2021/os-17-1213-2021-f07

Figure 7Latitudinal and bathymetric variability of εNd in the sector between 23 and 55 S. Water masses: Plata Plume Water (PPW), Subantarctic Shelf Water (SASW), Tropical Water (TW), South Atlantic Central Water (SACW), Antarctic Intermediate Water (AAIW), and Lower Circumpolar Deep Water (LCDW). Currents: Malvinas Current (MC) and Brazil Current (BC). Fronts: Subtropical Shelf Front (STSW), Brazil–Malvinas Confluence (BMC), and Santos Bifurcation (SB). Vertical axis in log(10) scale.

Download

https://os.copernicus.org/articles/17/1213/2021/os-17-1213-2021-f08

Figure 8Latitudinal and bathymetric variability of 207Pb/204Pb in the sector between 23 and 55 S. Río de la Plata (RdlP). Water masses: Plata Plume Water (PPW), Subantarctic Shelf Water (SASW), Tropical Water (TW), South Atlantic Central Water (SACW), Antarctic Intermediate Water (AAIW), and Lower Circumpolar Deep Water (LCDW). Currents: Malvinas Current (MC) and Brazil Current (BC). Fronts: Subtropical Shelf Front (STSW), Brazil–Malvinas Confluence (BMC), and Santos Bifurcation (SB). Vertical axis in log(10) scale.

Download

https://os.copernicus.org/articles/17/1213/2021/os-17-1213-2021-f09

Figure 9Latitudinal and bathymetric variability of 208Pb/204Pb in the sector between 23 and 55 S. Río de la Plata (RdlP). Water masses: Plata Plume Water (PPW), Subantarctic Shelf Water (SASW), Tropical Water (TW), South Atlantic Central Water (SACW), Antarctic Intermediate Water (AAIW), and Lower Circumpolar Deep Water (LCDW). Currents: Malvinas Current (MC) and Brazil Current (BC). Fronts: Subtropical Shelf Front (STSW), Brazil–Malvinas Confluence (BMC), and Santos Bifurcation (SB). Vertical axis in log(10) scale.

Download

5 Discussion

The integration of both isotopic signatures (εNd, 207Pb/204Pb, and 208Pb/204Pb) and hydrographic (water masses) and hydrodynamic (currents) information is presented in Figs. 7 to 9, respectively. This information is essential to infer both sediment sources and the role played by ocean circulation in the distribution of sediments in the study area.

5.1 Sediment sources

Recognizing the role of circulation in the deposition of sediments requires an association of the sedimentary provinces with potential source areas. Indeed, radiogenic isotopes are considered good sediment source fingerprints (Owens et al., 2016). Two seminal papers by Goldstein et al. (1984) and Bayon et al. (2015) used Nd isotopes and other proxies from the world's rivers and provided the basis for comprehending distribution detrital Nd in the world's oceans. Beny et al. (2020) provided the summary of Nd, Pb, and Sr signatures in the South Atlantic, looking for the potential sources and circulation in the area. More recently, a work by Höppner et al. (2021) provided new data on the isotopic signatures of the river sediments that feed the RdlP basin. It is worth noting that the RdlP–Paraná–Uruguay riverine system drains several types of terranes, such as pre-Cambrian rocks of the Brazilian shield, Paleozoic sediments, tholeiitic basalts from the Paraná Basin, and Cenozoic Andean rocks.

Table 2Nd and Pb isotopic values of distinct continental materials from Antarctica and southeastern South America.

n/a: not applicable.

Download Print Version | Download XLSX

Table 2 provides a list of Nd and Pb isotopic signatures of potential continental materials (rocks and sediments) for the study area. It is possible to recognize a trend of decreasing values of εNd towards the north, as already observed in our samples. Concerning Pb isotopes, the small number of data hampers the recognition of a trend.

Isotopic distinctions and similarities among the sectors are recognized from the interpretation of the results of the discriminant analysis (Fig. 4). Sediments from Argentina and part of the Punta del Este Basin present isotopic signatures similar to the values obtained for Patagonia (Gaiero et al., 2007; Bayon et al., 2015; Khondoker et al., 2018). The deepest samples of the dataset, located in the Punta del Este Basin at water depths between 3579 and 4066 m, present εNd values of 5.33 and 4.26, respectively. These values are consistent with those from the Antarctic Peninsula and West Antarctica (Roy et al., 2007). They can indicate a provenance of sediments via the flow of the Upper and Lower Circumpolar Deep Water masses (UCDW and LCDW, respectively) (Beny et al., 2020) or even from ice-rafted debris (Bozzano et al., 2021). Another sample, located at 2378 m, presents an εNd value of 4.80 but is presently under the influence of the NADW southward flow (Fig. 7). The distinct character of these samples also resides in the fact that they are lower 207Pb/204Pb and higher 208Pb/204Pb radiogenic than those located in shallower areas (Figs. 8 and 9). The remainder of the Punta del Este Basin samples, situated on the shelf, might represent a mixture of Patagonian and Río de la Plata sediments.

Most of the samples from the Pelotas Basin are under the influence of the RdlP. Apart from Nd and Pb isotope values, other independent proxies confirm the Plata Plume Water (PPW) as a source of the sediments to the southern Brazilian margin (Pelotas Basin) and part of the southeastern margin (Santos Basin). Campos et al. (2008) and Nagai et al. (2014a) used clay mineralogy to indicate sediments from the Río de la Plata to the north. Also, the maps presented by Govin et al. (2012) show similarities in ln(Ti/Al) and ln(Fe/K) between the Uruguayan and southern Brazilian upper margin. Mathias et al. (2014) used magnetic properties of sediments in a core located at the latitude of 2530 S to recognize the influence of the Río de la Plata on the southern Brazilian shelf since 2 cal kyr BP. Finally, in a study that included the analysis of potential source rocks from the continent, Mantovanelli et al. (2018) confirmed the contribution of the Paraná Basin basalts along the Holocene off the southern Brazilian shelf (27 S). The authors observed a remarkable change to less radiogenic Nd in the sedimentary column further north (23 S).

The samples from the Santos Basin present lower radiogenic Nd and higher radiogenic Pb values, thus indicating a pre-Cambrian source, as Mantovanelli et al. (2018) stated. Nevertheless, the values obtained for Pb isotopes differ significantly from those reported in the literature for the pre-Cambrian metasediments and granites of the southeastern Brazilian coast (Ragatky et al., 2000; Moraes et al., 2004; Mendes et al., 2011). A possible explanation for this discrepancy is that the input of sediments from the adjacent coast is hampered by the Serra do Mar mountain chain, limiting the development of expressive drainage basins in the area (Riccomini et al., 2010; Cogné et al., 2011). In this sense, we cannot rule out the possibility that a significant part of sediments that presently cover the shelf and upper slope of the Santos Basin originates further north and is transported by the Brazil Current and derived shelf dynamics (Castro and Miranda, 1998; Silveira et al., 2017).

5.2 Isotope fingerprinting and ocean circulation

The geochemical fingerprinting approach confirmed the suitability of using Nd and Pb isotopes (except 206Pb/204Pb) as reliable proxies for discrimination among the distinct sectors of the southwestern Atlantic margin. Indeed, the first axis provided more than 99 % of explained variance (Fig. 4). The distribution of the samples, together with the recognition of the potential sources (Table 2), allows tracing a correlation among isotopic signatures, sediment sources, and ocean circulation.

Figures 7 to 9 present the bathymetrical variations of the isotopes and positions of the STSF (continuous line) and SB (continuous line with horizontal bars) identified in the LLC2160 output. The positions of both oceanographic features in the LLC2160 simulation are broadly consistent with previous studies (e.g., Boebel et al., 1999a b; Piola et al., 2008). The LLC2160 output, together with the isotopic values, allows us to present the bathymetrical variations of those features. As observed, there are clear distinctions in the signature corresponding to both fronts. The STSF presents only minor seasonal variations, and its control is probably related to the interaction between the RdlP plume and the subsurface water mass distribution. During austral summer, the strong stratification (Möller et al., 2008) inhibits RdlP sedimentation southward of the STSF. During austral winter, the northeastward RdlP plume promotes the offshore displacement of subtropical waters (Möller et al., 2008), enabling the deposition of fine sediments on the shelf north of the STSF. On the upper and middle slope, the southward displacement of the thickened Brazil Current, carrying the recirculated AAIW, likely limits RdlP sedimentation (Schmid et al., 2000). There are apparent differences in the Nd and Pb signatures in the intermediate zone at about 34–35 S; this boundary might represent the northernmost limit of the BMC (Benthien and Müller, 2000; Pezzi et al., 2009).

This integrated analysis suggests no transport of sediments from the Argentinean sector to the southern Brazilian margin. On the other hand, based on the same analysis, we can confirm that sediments from the Río de la Plata reach, at least partially, the Santos sector, i.e., to the north of 28 S. Concerning the SB, there is a clear distinction in isotopic signatures below the 500 m isobath, with less radiogenic Nd prevailing to the north of the bifurcation. We thus argue that both STSF and SB also separate distinct geochemical provinces on the southwestern Atlantic margin.

The Argentinean and part of the Uruguayan upper margins are covered by Andean–Patagonian sediments redistributed by the shelf circulation and Malvinas Current. The STSF and BMC block the transport of these sediments to the north. This finding corroborates Hernández-Molina et al. (2016) and Franco-Fraguas et al. (2016), who defined the northernmost limit of a mega-contouritic feature on the Uruguayan slope. Sediments located deeper than the 2000 m isobath present an Antarctic signature, transported either by the bottom circulation (UCDW and LCDW) or ice-rafted debris.

Sediments from the Río de la Plata estuary advance along the inner shelf towards southern Brazil, and a mixture of Pelotas and Santos signatures are observed between 28 and 30 S. This mixture is visible in the scatter plot presented in Fig. 4, in which sediments of the Pelotas Basin constitute a mixture of distinct populations, i.e., Santos Basin and Río de la Plata. It is essential to highlight the fact that, on interannual timescales, the influence of the El Niño–Southern Oscillation (ENSO) in the precipitation regime determines changes in the freshwater outflow of the RdlP. Cold and warm episodes of ENSO cause drought and abundant rainfall in Uruguay, southern Brazil, and northeastern Argentina (Pisciottano et al., 1994; Cazes-Boezio et al., 2003). In addition, changes in the wind patterns during the warm phase of ENSO determine the influence of the PPW towards higher latitudes. In conjunction with the Coriolis force, this phenomenon determines that the PPW follows a NE direction close to the shelf break, explaining the distribution up to 28 S and, in anomalous years, 25 S (Piola et al., 2005).

Finally, sediments located northward of 27 S originate from the pre-Cambrian rocks that dominate the coastal domains off SE and E Brazil, being mainly transported by the intense flow of the BC on the outer shelf and upper slope. Limited input comes from the small rivers that drain the mountainous areas of the Serra do Mar, as previously reported by Lourenço et al. (2017) and de Mahiques et al. (2017).

6 Conclusions

In this paper, we use Nd and Pb radiogenic isotopes to recognize the role of ocean circulation in the sediment distribution of the southwestern Atlantic margin.

Andean and continental Patagonian sediments are the primary source for the deposits of the Argentinean and Uruguayan shelves, while the lower slope is more influenced by more distant sources, such as the Antarctic Peninsula. Nevertheless, sediments on the shelf and upper slope are carried by the flows of the SASW and AAIW, while the UCDW and LCDW transport sediments from the lower slope.

The Río de la Plata is the primary influencer of the sediments off southern Brazil up to the 27 S parallel. The sediments are transported northwards by the PPW, which is transported by a wind-driven current. A mixture of sediments from the PPW and the north is transported towards the slope between 34 and 28 S.

Finally, pre-Cambrian rocks are the primary sources of the sediments deposited further north. They originate from rivers located northward of the area of study and, on a smaller scale, by the small drainages that face the ocean in the Serra do Mar region.

We propose that the main oceanographic boundaries of the southwestern South Atlantic margin, i.e., the Subtropical Shelf Front and the Santos Bifurcation, separate distinct geochemical provinces.

Data availability

All of the data used in this paper are presented in the Supplement.

Supplement

The supplement related to this article is available online at: https://doi.org/10.5194/os-17-1213-2021-supplement.

Author contributions

MMdM was responsible for conceptualization, investigation, writing the original draft, review and editing, visualization, and supervision. PFF was responsible for conceptualization, investigation, writing the original draft, and review and editing. LB was responsible for conceptualization, investigation, writing the original draft, and review and editing. RV was responsible for conceptualization, investigation, writing the original draft, and review and editing. LO was responsible for writing the original draft, visualization, and review and editing. CBR was responsible for investigation, writing the original draft, visualization, and review and editing. RFdS was responsible for investigation, writing the original draft, and review and editing. BSMK was responsible for investigation, writing the original draft, and review and editing. RCLF was responsible for supervision, project administration, funding acquisition, writing the original draft, and review and editing. MCB was responsible for supervision, project administration, funding acquisition, writing the original draft, and review and editing.

Competing interests

The contact author has declared that neither they nor their co-authors have any competing interests.

Disclaimer

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Acknowledgements

The authors acknowledge the crew of R/V Alpha Crucis and participants of the research cruises Mudbelts I and II as well as Talude I and II for helping during the sampling surveys. This work is a contribution to the Grupo de Investigación en Ciencia y Tecnología Marina (CINCYTEMA) and to the MOU between the Oceanographic Institute of University of São Paulo (Brazil) and the Facultad de Ciencias of the Universidad de La Republica (Uruguay), which are institutions to whom the authors are indebted.

Financial support

This work was financially supported by the São Paulo Science Foundation (FAPESP) by grants 2010/06147-5, 2014/08266-2, 2015/17763-2, 2016/22194-0, and 2019/00256-1. In addition, Michel Michaelovitch de Mahiques acknowledges the Brazilian Council of Scientific Research (CNPq) for research grant 300962/2018-5.

Review statement

This paper was edited by Arvind Singh and reviewed by Yunchao Shu and two anonymous referees.

References

Baptista, M. S. and Conti, L. A.: The Staircase Structure of the Southern Brazilian Continental Shelf, Mathematical Problems in Engineering, 2009, 1–17, https://doi.org/10.1155/2009/624861, 2009. 

Barreto, C. J. S., Lafon, J. M., de Lima, E. F., and Sommer, C. A.: Geochemical and Sr–Nd–Pb isotopic insight into the low-Ti basalts from southern Paraná Igneous Province, Brazil: the role of crustal contamination, Int. Geol. Rev., 58, 1324–1349, https://doi.org/10.1080/00206814.2016.1147988, 2016. 

Basile, I., Grousset, F. E., Revel, M., Petit, J. R., Biscaye, P. E., and Barkov, N. I.: Patagonian origin of glacial dust deposited in East Antarctica (Vostok and Dome C), during glacial stages 2, 4 and 6, Earth Planet. Sc. Lett., 146, 573–589, 1997. 

Bassetto, M., Alkmim, F. F., Szatmari, P., and Mohriak, W. U.: The oceanic segment of the southern Brazilian margin: Morpho-structural domains and their tectonic significance, in: Atlantic Rifts and Continental Margins, edited by: Mohriak, W. and Taiwani, M., Geophysical Monograph Series, American Geophysical Union, 235–259, 2000. 

Bayon, G., Toucanne, S., Skonieczny, C., André, L., Bermell, S., Cheron, S., Dennielou, B., Etoubleau, J., Freslon, N., Gauchery, T., Germain, Y., Jorry, S. J., Ménot, G., Monin, L., Ponzevera, E., Rouget, M. L., Tachikawa, K., and Barrat, J. A.: Rare earth elements and neodymium isotopes in world river sediments revisited, Geochim. Cosmochim. Ac., 170, 17–38, https://doi.org/10.1016/j.gca.2015.08.001, 2015. 

Benthien, A. and Müller, P. J.: Anomalously low alkenone temperatures caused by lateral particle and sediment transport in the Malvinas Current region, western Argentine Basin, Deep-Sea Res. Pt. I, 47, 2369–2393, https://doi.org/10.1016/s0967-0637(00)00030-3, 2000. 

Beny, F., Bout-Roumazeilles, V., Davies, G. R., Waelbroeck, C., Bory, A., Tribovillard, N., Delattre, M., and Abraham, R.: Radiogenic isotopic and clay mineralogical signatures of terrigenous particles as water-mass tracers: New insights into South Atlantic deep circulation during the last termination, Quaternary Sci. Rev., 228, 106089, https://doi.org/10.1016/j.quascirev.2019.106089, 2020. 

Berden, G., Charo, M., Möller, O. O., and Piola, A. R.: Circulation and Hydrography in the Western South Atlantic Shelf and Export to the Deep Adjacent Ocean: 30 S to 40 S, J. Geophys. Res.-Oceans, 125, e2020JC016500, https://doi.org/10.1029/2020jc016500, 2020. 

Berkowsky, F.: Variaciones mineralógicas en sedimentos del Río de la Plata, VII Congreso Geológico Argentino, Neuquén, 9–15 April 2021, Asociación Geológica Argentina, 649–658, 1978. 

Berkowsky, F.: Arenas del Río de la Plata: una excepción a la relación entre composición de areniscas y la tectónica de placas, Primera Reunión Argentina de Sedimentología, La Plata, Argentina, 6–10 October 1986, Asociación Argentina de Sedimentología, 263–266, 1986. 

Biló, T. C., da Silveira, I. C. A., Belo, W. C., de Castro, B. M., and Piola, A. R.: Methods for estimating the velocities of the Brazil Current in the pre-salt reservoir area off southeast Brazil (23 S–26 S), Ocean Dynam., 64, 1431–1446, https://doi.org/10.1007/s10236-014-0761-2, 2014. 

Blanchet, C. L.: A database of marine and terrestrial radiogenic Nd and Sr isotopes for tracing earth-surface processes, Earth Syst. Sci. Data, 11, 741–759, https://doi.org/10.5194/essd-11-741-2019, 2019. 

Boebel, O., Schmid, C., and Zenk, W.: Flow and recirculation of Antarctic Intermediate Water across the Rio Grande Rise, J. Geophys. Res.-Oceans, 102, 20967–20986, https://doi.org/10.1029/97jc00977, 1997. 

Boebel, O., Davis, R. E., Ollitrault, M., Peterson, R. G., Richardson, P. L., Schmid, C., and Zenk, W.: The intermediate depth circulation of the western South Atlantic, Geophys. Res. Lett., 26, 3329–3332, https://doi.org/10.1029/1999gl002355, 1999a. 

Boebel, O., Schmid, C., and Zenk, W.: Kinematic elements of Antarctic Intermediate Water in the western South Atlantic, Deep-Sea Res. Pt. II, 46, 355–392, https://doi.org/10.1016/s0967-0645(98)00104-0, 1999b. 

Bozzano, G., Violante, R. A., and Cerredo, M. E.: Middle slope contourite deposits and associated sedimentary facies off NE Argentina, Geo-Mar. Lett., 31, 495–507, https://doi.org/10.1007/s00367-011-0239-x, 2011. 

Bozzano, G., Martín, J., Spoltore, D. V., and Violante, R. A.: Los cañones submarinos del margen continental Argentino: una síntesis sobre su génesis y dinámica sedimentaria, Latin American Journal of Sedimentology and Basin Analysis, 24, 85–101, 2017. 

Bozzano, G., Cerredo, M. E., Remesal, M., Steinmann, L., Hanebuth, T. J. J., Schwenk, T., Baqués, M., Hebbeln, D., Spoltore, D., Silvestri, O., Acevedo, R. D., Spiess, V., Violante, R. A., and Kasten, S.: Dropstones in the Mar del Plata Canyon Area (SW Atlantic): Evidence for Provenance, Transport, Distribution, and Oceanographic Implications, Geochem. Geophy. Geosy., 22, e2020GC009333, https://doi.org/10.1029/2020gc009333, 2021. 

Burone, L., Franco-Fraguas, P., de Mahiques, M. M., and Ortega, L.: Geomorphological and Sedimentological Characterization of the Uruguayan Continental Margin: A Review and State of Art, Journal of Sedimentary Environments, 3, 253–264, https://doi.org/10.12957/jse.2018.39150, 2018. 

Campos, E. J. D., Mulkherjee, S., Piola, A. R., and de Carvalho, F. M. S.: A note on a mineralogical analysis of the sediments associated with the Plata River and Patos Lagoon outflows, Cont. Shelf Res., 28, 1687–1691, https://doi.org/10.1016/j.csr.2008.03.014, 2008. 

Carranza, A., Recio, A. M., Kitahara, M., Scarabino, F., Ortega, L., López, G., Franco-Fraguas, P., De Mello, C., Acosta, J., and Fontan, A.: Deep-water coral reefs from the Uruguayan outer shelf and slope, Marine Biodivers., 42, 411–414, https://doi.org/10.1007/s12526-012-0115-6, 2012. 

Castro, B. M. and Miranda, L. B.: Physical Oceanography of the Western Atlantic continental shelf located between 4N and 34S, in: The Sea, edited by: Robinson, A. R. and Brink, K. H., John Wiley & Sons, New York, 210–251, 1998. 

Cazes-Boezio, G., Robertson, A. W., and Mechoso, C. R.: Seasonal Dependence of ENSO Teleconnections over South America and Relationships with Precipitation in Uruguay, J. Climate, 16, 1159–1176, https://doi.org/10.1175/1520-0442(2003)16<1159:Sdoeto>2.0.Co;2, 2003. 

Chen, S., Qiu, B., Klein, P., Wang, J., Torres, H., Fu, L.-L., and Menemenlis, D.: Seasonality in Transition Scale from Balanced to Unbalanced Motions in the World Ocean, J. Phys. Oceanogr., 48, 591–605, https://doi.org/10.1175/jpo-d-17-0169.1, 2018. 

Cogné, N., Gallagher, K., and Cobbold, P. R.: Post-rift reactivation of the onshore margin of southeast Brazil: Evidence from apatite (U–Th)/He and fission-track data, Earth Planet. Sc. Lett., 309, 118–130, https://doi.org/10.1016/j.epsl.2011.06.025, 2011. 

Corrêa, I. C. S.: Les variations du niveau de la mer durant les derniers 17.500 ans BP: l'exemple de la plate-forme continentale du Rio Grande do Sul-Brésil, Mar. Geol., 130, 163–178, https://doi.org/10.1016/0025-3227(95)00126-3, 1996. 

de Mahiques, M. M., Tassinari, C. C. G., Marcolini, S., Violante, R. A., Figueira, R. C. L., Silveira, I. C. A., Burone, L., and Sousa, S. H. M.: Nd and Pb isotope signatures on the Southeastern South American upper margin: Implications for sediment transport and source rocks, Mar. Geol., 250, 51–63, https://doi.org/10.1016/j.margeo.2007.11.007, 2008. 

de Mahiques, M. M., Hanebuth, T. J. J., Nagai, R. H., Bícego, M. C., Figueira, R. C. L., Sousa, S. H. M., Burone, L., Franco-Fraguas, P., Taniguchi, S., Salaroli, A. B., Dias, G. P., Prates, D. M., and Freitas, M. E. F.: Inorganic and organic geochemical fingerprinting of sediment sources and ocean circulation on a complex continental margin (São Paulo Bight, Brazil), Ocean Sci., 13, 209–222, https://doi.org/10.5194/os-13-209-2017, 2017. 

de Mahiques, M. M., Figueira, R. C. L., Sousa, S. H. d. M., Santos, R. F. d., Ferreira, P. A. d. L., Kim, B. S. M., Cazzoli y Goya, S., de Matos, M. C. S. N., and Bícego, M. C.: Sedimentation on the southern Brazilian shelf mud depocenters: Insights on potential source areas, J. S. Am. Earth Sci., 100, 102577, https://doi.org/10.1016/j.jsames.2020.102577, 2020. 

DePaolo, D. J.: Neodymium isotopes in the Colorado Front Range and crust–mantle evolution in the Proterozoic, Nature, 291, 193–196, https://doi.org/10.1038/291193a0, 1981. 

Depetris, P. J. and Griffin, J. J.: Suspended Load in the Rio De La Plata Drainage Basin, Sedimentology, 11, 53–60, https://doi.org/10.1111/j.1365-3091.1968.tb00840.x, 1968. 

Duarte, C. S. L. and Viana, A. R.: Santos Drift System: stratigraphic organization and implications for late Cenozoic palaeocirculation in the Santos Basin, SW Atlantic Ocean, Geological Society, London, Special Publications, 276, 171–198, https://doi.org/10.1144/gsl.sp.2007.276.01.09, 2007. 

Emilsson, I.: The shelf and coastal waters off southern Brazil, Boletim do Instituto Oceanográfico, 11, 101–112, https://doi.org/10.1590/S0373-55241961000100004, 1961. 

Etchichury, M. C. and Remiro, J. R.: Muestras de fondo de la plataforma continental comprendida entre los paralelos 34 y 36 30 de latitud sur y los meridianos 53 10 y 56 30 de longitud oeste, Revista del Museo Argentino de Ciencias Naturales Bernardino Rivadavia, VI, 1–70, 1960. 

Etchichury, M. C. and Remiro, J. R.: La corriente de Malvinas y los sedimentos pampeanopatagónicos, Revista del Museo Argentino de Ciencias Naturales Bernardino Rivadavia, 1, 1–11, 1963. 

Fernandes, A. M., da Silveira, I. C. A., Calado, L., Campos, E. J. D., and Paiva, A. M.: A two-layer approximation to the Brazil Current–Intermediate Western Boundary Current System between 20 S and 28 S, Ocean Model., 29, 154–158, https://doi.org/10.1016/j.ocemod.2009.03.008, 2009. 

Figueiredo, A. G. and Madureira, L. S. P.: Topografia, composição, refletividade do substrato marinho e identificação de províncias sedimentares na Regiao Sudeste-Sul do Brasil, Série Documentos Técnicos do Programa REVIZEE Score Sul, Instituto Oceanográfico – USP, São Paulo, 64 pp., 2004. 

Framiñan, M. B. and Brown, O. B.: Study of the Río de la Plata turbidity front, Part 1: spatial and temporal distribution, Cont. Shelf Res., 16, 1259–1282, https://doi.org/10.1016/0278-4343(95)00071-2, 1996. 

Franco-Fraguas, P., Burone, L., Mahiques, M., Ortega, L., Urien, C., Muñoz, A., López, G., Marin, Y., Carranza, A., Lahuerta, N., and de Mello, C.: Hydrodynamic and geomorphological controls on surface sedimentation at the Subtropical Shelf Front/Brazil–Malvinas Confluence transition off Uruguay (Southwestern Atlantic Continental Margin), Mar. Geol., 349, 24–36, https://doi.org/10.1016/j.margeo.2013.12.010, 2014. 

Franco-Fraguas, P., Burone, L., Mahiques, M., Ortega, L., and Carranza, A.: Modern sedimentary dynamics in the Southwestern Atlantic Contouritic Depositional System: New insights from the Uruguayan margin based on a geochemical approach, Mar. Geol., 376, 15–25, https://doi.org/10.1016/j.margeo.2016.03.008, 2016. 

Franco-Fraguas, P., Burone, L., Goso, C., Scarabino, F., Muzio, R., Carranza, A., Ortega, L., Muñoz, A., and Mahiques, M.: Sedimentary processes in the head of the Cabo Polonio mega slide canyon (Southwestern Atlantic margin off Uruguay), Latin American Journal of Sedimentology and Basin Analysis, 24, 31–44, 2017. 

Frenz, M., Höppner, R., Stuut, J.-B., Wagner, T., and Henrich, R.: Surface sediment bulk geochemistry and grain-size composition related to the oceanic circulation along the South American continental margin in the Southwest Atlantic, in: The South Atlantic in the Late Quaternary: Reconstruction of material budgets and current Systems, edited by: Wefer, G., Mulitza, S., and Ratmeyer, V., Springer-Verlag, Berlin, 347–373, 2003. 

Gaiero, D. M., Brunet, F., Probst, J.-L., and Depetris, P. J.: A uniform isotopic and chemical signature of dust exported from Patagonia: Rock sources and occurrence in southern environments, Chem. Geol., 238, 107–120, https://doi.org/10.1016/j.chemgeo.2006.11.003, 2007. 

Goldstein, S. L., O'Nions, R. K., and Hamilton, P. J.: A Sm-Nd isotopic study of atmospheric dusts and particulates from major river systems, Earth Planet. Sc. Lett., 70, 221–236, https://doi.org/10.1016/0012-821x(84)90007-4, 1984. 

Govin, A., Holzwarth, U., Heslop, D., Ford Keeling, L., Zabel, M., Mulitza, S., Collins, J. A., and Chiessi, C. M.: Distribution of major elements in Atlantic surface sediments (36 N–49 S): Imprint of terrigenous input and continental weathering, Geochem. Geophy. Geosy., 13, Q01013, https://doi.org/10.1029/2011gc003785, 2012. 

Hammer, Ø., Harper, D. A. T., and Ryan, P. D.: PAST: Paleontological statistics software package for education and data analysis, Palaeontologia Electronica, 4, 9, 2001. 

Henry, F., Probst, J. L., Thouron, D., Depetris, P., and Garçon, V.: Nd-Sr isotopic compositions of dissolved and particulate material transported by the Parana and Uruguay rivers during high (December 1993) and low (September 1994) water periods. / Compositions isotopiques de Nd et Sr des matières en suspension et dissoutes transportées par les fleuves Parana et Uruguay en périodes de hautes (décembre 1993) et basses (septembre 1994) eaux, Sciences Géologiques. Bulletin, 49, 89–100, https://doi.org/10.3406/sgeol.1996.1937, 1996. 

Hernandez-Molina, F. J., Paterlini, M., Violante, R., Marshall, P., de Isasi, M., Somoza, L., and Rebesco, M.: Contourite depositional system on the Argentine Slope: An exceptional record of the influence of Antarctic water masses, Geology, 37, 507–510, https://doi.org/10.1130/g25578a.1, 2009. 

Hernández-Molina, F. J., Paterlini, M., Somoza, L., Violante, R., Arecco, M. A., de Isasi, M., Rebesco, M., Uenzelmann-Neben, G., Neben, S., and Marshall, P.: Giant mounded drifts in the Argentine Continental Margin: Origins, and global implications for the history of thermohaline circulation, Mar. Petrol. Geol., 27, 1508–1530, https://doi.org/10.1016/j.marpetgeo.2010.04.003, 2010. 

Hernández-Molina, F. J., Soto, M., Piola, A. R., Tomasini, J., Preu, B., Thompson, P., Badalini, G., Creaser, A., Violante, R. A., Morales, E., Paterlini, M., and De Santa Ana, H.: A contourite depositional system along the Uruguayan continental margin: Sedimentary, oceanographic and paleoceanographic implications, Mar. Geol., 378, 333–349, https://doi.org/10.1016/j.margeo.2015.10.008, 2015. 

Hernández-Molina, F. J., Soto, M., Piola, A. R., Tomasini, J., Preu, B., Thompson, P., Badalini, G., Creaser, A., Violante, R. A., Morales, E., Paterlini, M., and De Santa Ana, H.: A contourite depositional system along the Uruguayan continental margin: Sedimentary, oceanographic and paleoceanographic implications, Mar. Geol., 378, 333–349, https://doi.org/10.1016/j.margeo.2015.10.008, 2016. 

Höppner, N., Chiessi, C. M., Lucassen, F., Zavala, K., Becchio, R. A., and Kasemann, S. A.: Modern isotopic signatures of Plata River sediments and changes in sediment supply to the western subtropical South Atlantic during the last 30 kyr, Quaternary Sci. Rev., 259, 106910, https://doi.org/10.1016/j.quascirev.2021.106910, 2021. 

Jacobsen, S. B. and Wasserburg, G. J.: Sm-Nd isotopic evolution of chondrites, Earth Planet. Sc. Lett., 50, 139–155, https://doi.org/10.1016/0012-821x(80)90125-9, 1980. 

Jeandel, C., Arsouze, T., Lacan, F., Téchiné, P., and Dutay, J. C.: Isotopic Nd compositions and concentrations of the lithogenic inputs into the ocean: A compilation, with an emphasis on the margins, Chem. Geol., 239, 156–164, https://doi.org/10.1016/j.chemgeo.2006.11.013, 2007. 

Kessarkar, P. M., Rao, V. P., Ahmad, S. M., and Babu, G. A.: Clay minerals and Sr–Nd isotopes of the sediments along the western margin of India and their implication for sediment provenance, Mar. Geol., 202, 55–69, https://doi.org/10.1016/s0025-3227(03)00240-8, 2003. 

Khondoker, R., Weiss, D., van de Flierdt, T., Rehkämper, M., Kreissig, K., Coles, B. J., Strekopytov, S., Humphreys-Williams, E., Dong, S., Bory, A., Bout-Roumazeilles, V., Smichowski, P., Cid-Agüero, P., Babinski, M., Losno, R., and Monna, F.: New constraints on elemental and Pb and Nd isotope compositions of South American and Southern African aerosol sources to the South Atlantic Ocean, Geochemistry, 78, 372–384, https://doi.org/10.1016/j.chemer.2018.05.001, 2018. 

Kowsmann, R. O. and Costa, M. P. A.: Sedimentação quaternária da margem continental brasileira e das áreas adjacentes, REMAC, Petrobrás, Rio de Janeiro, 55 pp., 1979 (in Portuguese). 

Lantzsch, H., Hanebuth, T. J. J., Chiessi, C. M., Schwenk, T., and Violante, R. A.: The high-supply, current-dominated continental margin of southeastern South America during the late Quaternary, Quaternary Res., 81, 339–354, https://doi.org/10.1016/j.yqres.2014.01.003, 2014. 

Legeais, J.-F., Ollitrault, M., and Arhan, M.: Lagrangian observations in the Intermediate Western Boundary Current of the South Atlantic, Deep-Sea Res. Pt. II, 85, 109–126, https://doi.org/10.1016/j.dsr2.2012.07.028, 2013. 

Lonardi, A. G., and Ewing, M.: Sediment transport and distribution in the Argentine Basin. 4. Bathymetry of the continental margin, Argentine Basin and other related provinces. Canyons and sources of sediments, in: Physics and Chemistry of the Earth, edited by: Ahrens, L. H., Press, F., Runcorn, S. K., and Urey, H. C., Pergamon Press, New York, 79–121, 1971. 

Lourenço, R. A., Magalhães, C. A., de Mahiques, M. M., Taniguchi, S., and Bícego, M. C.: Distribution of terrigenous and marine material along the Southeastern Brazilian continental margin, Regional Studies in Marine Science, 14, 118–125, https://doi.org/10.1016/j.rsma.2017.05.012, 2017. 

Lovecchio, J. P., Rohais, S., Joseph, P., Bolatti, N. D., and Ramos, V. A.: Mesozoic rifting evolution of SW Gondwana: A poly-phased, subduction-related, extensional history responsible for basin formation along the Argentinean Atlantic margin, Earth-Sci. Rev., 203, 103138, https://doi.org/10.1016/j.earscirev.2020.103138, 2020. 

Maamaatuaiahutapu, K., Garçon, V. C., Provost, C., Boulahdid, M., and Osiroff, A. P.: Brazil-Malvinas Confluence: Water mass composition, J. Geophys. Res., 97, 9493–9505, https://doi.org/10.1029/92jc00484, 1992. 

Maccali, J., Hillaire-Marcel, C., Carignan, J., and Reisberg, L. C.: Pb isotopes and geochemical monitoring of Arctic sedimentary supplies and water mass export through Fram Strait since the Last Glacial Maximum, Paleoceanography, 27, PA1201, https://doi.org/10.1029/2011pa002152, 2012. 

Maccali, J., Hillaire-Marcel, C., and Not, C.: Radiogenic isotope (Nd, Pb, Sr) signatures of surface and sea ice-transported sediments from the Arctic Ocean under the present interglacial conditions, Polar Res., 37, 1442982, https://doi.org/10.1080/17518369.2018.1442982, 2018. 

Magdaleno, G. B., Petronilho, L. A., Ruiz, I. R., Babinski, M., Hollanda, M. H. B. M., and Martins, V. T. S.: Pb-Sr-Nd isotopoic characterization of USGS reference materials by TIMS at CPGeo-USP, II Workshop of inorganic mass spectrometry, São Paulo, 4–6 September 2017, available at: http://wims.igc.usp.br/wp-content/uploads/2017/07/Giselle-Magdaleno.pdf (last access: 20 December 2019), 2017. 

Maly, M., Schattner, U., Lobo, F., Ramos, R. B., Dias, R. J., Couto, D. M., Sumida, P. Y., and de Mahiques, M. M.: The Alpha Crucis Carbonate Ridge (ACCR): Discovery of a giant ring-shaped carbonate complex on the SW Atlantic margin, Sci. Rep.-UK, 9, 18697, https://doi.org/10.1038/s41598-019-55226-3, 2019. 

Mantovanelli, S. S., Tassinari, C. C. G., de Mahiques, M. M., Jovane, L., and Bongiolo, E.: Characterization of Nd radiogenic isotope signatures in sediments from the southwestern Atlantic Margin, Frontiers in Earth Science, 6, 74, https://doi.org/10.3389/feart.2018.00074, 2018. 

Matano, R. P., Palma, E. D., and Piola, A. R.: The influence of the Brazil and Malvinas Currents on the Southwestern Atlantic Shelf circulation, Ocean Sci., 6, 983–995, https://doi.org/10.5194/os-6-983-2010, 2010. 

Mathias, G. L., Nagai, R. H., Trindade, R. I. F., and de Mahiques, M. M.: Magnetic fingerprint of the late Holocene inception of the Río de la Plata plume onto the southeast Brazilian shelf, Palaeogeogr. Palaeocl., 415, 183–196, https://doi.org/10.1016/j.palaeo.2014.03.034, 2014. 

Melankholina, E. N. and Sushchevskaya, N. M.: Tectono-Magmatic Evolution of the South Atlantic Continental Margins with Respect to Opening of the Ocean, Geotectonics, 52, 173–193, https://doi.org/10.1134/s0016852118020061, 2018. 

Mendes, J. C., de Medeiros, S. R., and Chaves, E. A.: Assinatura isotópica de Sr e Nd do magmatismo cálcio-alcalino de alto-K na Faixa Ribeira central: o exemplo do Granito São Pedro em Lumiar, RJ, Revista Brasileira de Geociências, 41, 408–419, https://doi.org/10.25249/0375-7536.2011413408419, 2011. 

Miller, J. R., Mackin, G., and Orbock Miller, S. M.: Geochemical Fingerprinting, in: Application of Geochemical Tracers to Fluvial Sediment, edited by: Miller, J. R., Mackin, G., and Miller, S. M. O., SpringerBriefs in Earth Sciences, Springer, Cham, 11–51, 2015. 

Möller, O. O., Piola, A. R., Freitas, A. C., and Campos, E. J. D.: The effects of river discharge and seasonal winds on the shelf off southeastern South America, Cont. Shelf Res., 28, 1607–1624, https://doi.org/10.1016/j.csr.2008.03.012, 2008. 

Moraes, R. P., Figueiredo, B. R., and Lafon, J. M.: Pb-Isotopic tracing of metal-pollution sources in the Ribeira Valley, Southeastern Brazil, Terrae, 1, 26–33, 2004. 

Moulin, M., Aslanian, D., and Unternehr, P.: A new starting point for the South and Equatorial Atlantic Ocean, Earth-Sci. Rev., 98, 1–37, https://doi.org/10.1016/j.earscirev.2009.08.001, 2010. 

Muñoz, A., Fontan, A., Marin, Y., Carranza, A., Franco-Fraguas, P., and Rubio, L.: Informe de Campaña Uruguay 0110. Buque de Investigacion Oceanografica y Pesquera Miguel Oliver (SGM), Dinara, Montevideo, 67, 2010. 

Nagai, R. H., Ferreira, P. A. L., Mulkherjee, S., Martins, M. V., Figueira, R. C. L., Sousa, S. H. M., and de Mahiques, M. M.: Hydrodynamic controls on the distribution of surface sediments from the southeast South American continental shelf between 23 S and 38 S, Cont. Shelf Res., 89, 51–60, https://doi.org/10.1016/j.csr.2013.09.016, 2014a. 

Nagai, R. H., Sousa, S. H. M., and de Mahiques, M. M.: The southern Brazilian shelf, Geological Society, London, Memoirs, 41, 47–54, https://doi.org/10.1144/m41.5, 2014b. 

Núñez-Riboni, I., Boebel, O., Ollitrault, M., You, Y., Richardson, P. L., and Davis, R.: Lagrangian circulation of Antarctic Intermediate Water in the subtropical South Atlantic, Deep-Sea Res. Pt. II, 52, 545–564, https://doi.org/10.1016/j.dsr2.2004.12.006, 2005. 

Nürnberg, D. and Müller, R. D.: The tectonic evolution of the South Atlantic from Late Jurassic to present, Tectonophysics, 191, 27–53, https://doi.org/10.1016/0040-1951(91)90231-g, 1991. 

Owens, P. N., Blake, W. H., Gaspar, L., Gateuille, D., Koiter, A. J., Lobb, D. A., Petticrew, E. L., Reiffarth, D. G., Smith, H. G., and Woodward, J. C.: Fingerprinting and tracing the sources of soils and sediments: Earth and ocean science, geoarchaeological, forensic, and human health applications, Earth-Sci. Rev., 162, 1–23, https://doi.org/10.1016/j.earscirev.2016.08.012, 2016. 

Palazon, L. and Navas, A.: Variability in source sediment contributions by applying different statistic test for a Pyrenean catchment, J. Environ. Manage., 194, 42–53, https://doi.org/10.1016/j.jenvman.2016.07.058, 2017. 

Palma, E. D., Matano, R. P., and Piola, A. R.: A numerical study of the Southwestern Atlantic Shelf circulation: Stratified ocean response to local and offshore forcing, J. Geophys. Res.-Oceans, 113, C11010, https://doi.org/10.1029/2007JC004720, 2008. 

Parker, G., Violante, R., and Paterlini, C. M.: Fisiografía de la Plataforma Continental, in: Relatorio, 13o Congreso Geologico Argentino, edited by: Ramos, V. A., and Turic, M. A., Asociación Geológica Argentina, Buenos Aires, 1–16, 1996. 

Pezzi, L. P., de Souza, R. B., Acevedo, O., Wainer, I., Mata, M. M., Garcia, C. A. E., and de Camargo, R.: Multiyear measurements of the oceanic and atmospheric boundary layers at the Brazil-Malvinas confluence region, J. Geophys. Res., 114, D19103, https://doi.org/10.1029/2008jd011379, 2009. 

Piola, A. R. and Matano, R. P.: Brazil and Falklands (Malvinas) currents, in: Encyclopedia of Ocean Sciences, edited by: Steele, J. H., Thorpe, S. A., and Turekian, K. K., Academic Press, London, 340–349, 2001. 

Piola, A. R. and Matano, R. P.: Ocean Currents: Atlantic Western Boundary—Brazil Current/Falkland (Malvinas) Current, in: Encyclopedia of Ocean Sciences, edited by: Cochran, J. K., Bokuniewicz, H. J., and Yager, P. L., Elsevier, Amsterdam, 414–420, 2019. 

Piola, A. R., Matano, R. P., Palma, E. D., Möller, O. O., and Campos, E. J. D.: The influence of the Plata River discharge on the western South Atlantic shelf, Geophys. Res. Lett., 32, L01603, https://doi.org/10.1029/2004GL021638, 2005. 

Piola, A. R., Möller, O. O., Guerrero, R. A., and Campos, E. J. D.: Variability of the subtropical shelf front off eastern South America: Winter 2003 and summer 2004, Cont. Shelf Res., 28, 1639–1648, https://doi.org/10.1016/j.csr.2008.03.013, 2008. 

Piola, A. R., Palma, E. D., Bianchi, A. A., Castro, B. M., Dottori, M., Guerrero, R. A., Marrari, M., Matano, R. P., Möller Jr., O. O., and Saraceno, M.: Physical oceanography of the SW Atlantic Shelf: A review, in: Plankton ecology of the southwestern Atlantic, edited by: Hoffmeyer, M. S., Sabatini, M. E., Brandini, F. P., Calliari, D. L., and Santinelli, N. H., Springer, Cham, 37–56, 2018. 

Piola, A. R., Campos, E. J. D., Möller, O. O., Charo, M., and Martinez, C.: Subtropical Shelf Front off eastern South America, J. Geophys. Res.-Oceans, 105, 6565–6578, https://doi.org/10.1029/1999jc000300, 2000. 

Pisciottano, G., Díaz, A., Cazess, G., and Mechoso, C. R.: El Niño-Southern Oscillation Impact on Rainfall in Uruguay, J. Climate, 7, 1286–1302, https://doi.org/10.1175/1520-0442(1994)007<1286:Ensoio>2.0.Co;2, 1994. 

Potter, P. E.: South American modern beach sand and plate tectonics, Nature, 311, 645–648, 1984. 

Preu, B., Hernández-Molina, F. J., Violante, R., Piola, A. R., Paterlini, C. M., Schwenk, T., Voigt, I., Krastel, S., and Spiess, V.: Morphosedimentary and hydrographic features of the northern Argentine margin: The interplay between erosive, depositional and gravitational processes and its conceptual implications, Deep-Sea Res. Pt. I, 75, 157–174, https://doi.org/10.1016/j.dsr.2012.12.013, 2013. 

Qiao, L., Liu, S., Xue, W., Liu, P., Hu, R., Sun, H., and Zhong, Y.: Spatiotemporal variations in suspended sediments over the inner shelf of the East China Sea with the effect of oceanic fronts, Estuar. Coast. Shelf S., 234, 106600, https://doi.org/10.1016/j.ecss.2020.106600, 2020. 

Ragatky, D., Tupinambá, M., and Duarte, B. P.: Sm/Nd data of metasedimentary rocks from the central segment of Ribeira Belt, southeastern Brazil, Revista Brasileira de Geociências, 30, 165–168, 2000. 

Razik, S., Chiessi, C. M., Romero, O. E., and von Dobeneck, T.: Interaction of the South American Monsoon System and the Southern Westerly Wind Belt during the last 14 kyr, Palaeogeogr. Palaeocl., 374, 28–40, https://doi.org/10.1016/j.palaeo.2012.12.022, 2013. 

Razik, S., Govin, A., Chiessi, C. M., and von Dobeneck, T.: Depositional provinces, dispersal, and origin of terrigenous sediments along the SE South American continental margin, Mar. Geol., 363, 261–272, https://doi.org/10.1016/j.margeo.2015.03.001, 2015. 

Reis, A. T., Silva, C. G., Gorini, M. A., Leão, R., Pinto, N., Perovano, R., Santos, M. V. M., Guerra, J. V., Jeck, I. K., and Tavares, A. A. A.: The Chuí Megaslide Complex: Regional-Scale Submarine Landslides on the Southern Brazilian Margin, in: Submarine Mass Movements and their Consequences, edited by: Lamarche, G., Mountjoy, J., Bull, S., Hubble, T., Krastel, S., Lane, E., Micallef, A., Moscardelli, L., Mueller, C., Pecher, I., and Woelz, S., Advances in Natural and Technological Hazards Research, 41, Springer, Cham, 115–123, 2016. 

Riccomini, C., Grohmann, C. H., Sant'Anna, L. G., and Hiruma, S. T.: A captura das cabeceiras do Rio Tietê pelo Rio Paraíba do Sul, in: A Obra de Aziz Nacib Ab'Sáber, edited by: Modenesi-Gauttieri, M. C., Bartorelli, A., Mantesso-Neto, V., Carneiro, C. D. R., and Lisboa, M. B. A. L., BecaBALL, São Paulo, 157–169, 2010 (in Portuguese). 

Roig, H. L., Moraes Rego, A. P., Dantas, E. L., Meneses, P. R., Walde, D. H. G., and Goia, S. M. L. C.: Assinatura isotópica Sm-Nd de sedimentos em suspensão: implicações na caracterização da proveniência dos sedimentos do Rio Paraíba do Sul – SP, Revista Brasileira de Geociências, 35, 503–514, 2005. 

Roy, M., van de Flierdt, T., Hemming, S. R., and Goldstein, S. L.: 40Ar/39Ar ages of hornblende grains and bulk Sm/Nd isotopes of circum-Antarctic glacio-marine sediments: Implications for sediment provenance in the southern ocean, Chem. Geol., 244, 507–519, https://doi.org/10.1016/j.chemgeo.2007.07.017, 2007. 

Sato, K., Tassinari, C. C. G., Kawashita, K., and Petronilho, L.: A metodologia Sm–Nd no IGc-USP e suas aplicações, An. Acad. Bras. Cienc., 67, 313–336, 1995. 

Schattner, U., José Lobo, F., López-Quirós, A., Passos Nascimento, J. L., and Mahiques, M. M.: What feeds shelf-edge clinoforms over margins deprived of adjacent land sources? An example from southeastern Brazil, Basin Res., 32, 293–301, https://doi.org/10.1111/bre.12397, 2020. 

Schmid, C. and Garzoli, S. L.: New observations of the spreading and variability of the Antarctic Intermediate Water in the Atlantic, J. Mar. Res., 67, 815–843, https://doi.org/10.1357/002224009792006151, 2009. 

Schmid, C., Siedler, G., and Zenk, W.: Dynamics of Intermediate Water Circulation in the Subtropical South Atlantic, J. Phys. Oceanogr., 30, 3191–3211, https://doi.org/10.1175/1520-0485(2000)030<3191:doiwci>2.0.co;2, 2000. 

Severov, D. N., Pshennikov, V., and Remeslo, A. V.: Fronts and thermohaline structure of the Brazil–Malvinas Confluence System, Adv. Space Res., 49, 1373–1387, https://doi.org/10.1016/j.asr.2012.01.024, 2012. 

Signorini, S. R.: On the circulation and the volume transport of the Brazil Current between the Cape of São Tomé and Guanabara Bay, Deep-Sea Res., 25, 481–490, https://doi.org/10.1016/0146-6291(78)90556-8, 1978. 

Silveira, I. C. A., Foloni Neto, H., Costa, T. P., Schmidt, A. C. K., Pereira, A. F., Castro Filho, B. M., Soutelino, R. G., and Grossmann-Matheson, G. S.: Physical oceanography of Campos Basin continental slope and ocean region, in: Meteorology and Oceanography: regional environmental characterization of the Campos Basin, Southwest Atlantic. Habitats, edited by: Martins, R. P. and Grossman-Matheson, G. S., Elsevier, Rio de Janeiro, 135–190, 2017. 

Soto, M., Morales, E., Veroslavsky, G., de Santa Ana, H., Ucha, N., and Rodríguez, P.: The continental margin of Uruguay: Crustal architecture and segmentation, Mar. Petrol. Geol., 28, 1676–1689, https://doi.org/10.1016/j.marpetgeo.2011.07.001, 2011. 

Spadone, A. and Provost, C.: Variations in the Malvinas Current volume transport since October 1992, J. Geophys. Res., 114, C02002, https://doi.org/10.1029/2008jc004882, 2009. 

Steinmann, L., Baques, M., Wenau, S., Schwenk, T., Spiess, V., Piola, A. R., Bozzano, G., Violante, R., and Kasten, S.: Discovery of a giant cold-water coral mound province along the northern Argentine margin and its link to the regional Contourite Depositional System and oceanographic setting, Mar. Geol., 427, 106223, https://doi.org/10.1016/j.margeo.2020.106223, 2020. 

Storlazzi, C. D. and Reid, J. A.: The influence of El Niño-Southern Oscillation (ENSO) cycles on wave-driven sea-floor sediment mobility along the central California continental margin, Cont. Shelf Res., 30, 1582–1599, https://doi.org/10.1016/j.csr.2010.06.004, 2010. 

Subha Anand, S., Rahaman, W., Lathika, N., Thamban, M., Patil, S., and Mohan, R.: Trace Elements and Sr, Nd Isotope Compositions of Surface Sediments in the Indian Ocean: An Evaluation of Sources and Processes for Sediment Transport and Dispersal, Geochem. Geophy. Geosy., 20, 3090–3112, https://doi.org/10.1029/2019gc008332, 2019. 

Sverdrup, H. U., Johnson, M. W., and Fleming, R. H.: The Oceans, Their Physics, Chemistry, and General Biology, Prentice-Hall, New York, 1065 pp., 1942. 

Tarakanov, R. Y. and Morozov, E. G.: Flow of Antarctic Bottom Water at the output of the Vema Channel, Oceanology, 55, 153–161, https://doi.org/10.1134/s0001437015010166, 2015. 

Teruggi, M. E.: El material volcánico-piroclástico en la sedimentación pampeana, Revista de la Asociación Geológica de Argentina, 9, 184–191, 1954. 

Tomczak, M. and Godfrey, J. S.: CHAPTER 15 – Hydrology of the Atlantic Ocean, in: Regional Oceanography, Pergamon, Amsterdam, 279–296, 1994a. 

Tomczak, M. and Godfrey, J. S.: CHAPTER 14 – The Atlantic Ocean, in: Regional Oceanography, Pergamon, Amsterdam, 253–278, 1994b. 

Urien, C. M. and Ewing, M.: Recent Sediments and Environment of Southern Brazil, Uruguay, Buenos Aires, and Rio Negro Continental Shelf, in: The Geology of Continental Margins, edited by: Burk, C. A. and Drake, C. L., Springer Berlin Heidelberg, Berlin, Heidelberg, 157–177, 1974. 

Urien, C. M. and Martins, L. R.: Sedimentación marina en América del Sur Oriental, Memorias del seminario sobre ecología bentónica y sedimentación de la plataforma continental del Atlántico Sur, 9–12 May 1978, Montevideo, Uruguay, Unesco, 5–28, 1979. 

Urien, C. M., Martins, L. R., and Martins, I.: Modelos deposicionais na plataforma continental do Rio Grande do Sul (Brasil), Uruguai e Buenos Aires (Argentina), Notas Técnicas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil, 2, 13–25, 1980. 

Violante, R. A., Paterlini, C. M., Costa, I. C., Hernandez-Molina, J., Segovia, L. M., Cavallotto, J. L., Marcolini, S., Bozzano, G., Laprida, C., García Chapori, N., Bickert, T., and Spieß, V.: Sismoestratigrafia y evolucion geomorfologica del talud continental adyacente al litoral del este bonaerense, Argentina, Latin American Journal of Sedimentology and Basin Analysis, 17, 33–62, 2010.  

Violante, R. A., Paterlini, C. M., Marcolini, S. I., Costa, I. P., Cavallotto, J. L., Laprida, C., Dragani, W., Garcia Chapori, N., Watanabe, S., Totah, V., Rovere, E. I., and Osterrieth, M. L.: Argentine continental shelf: morphology, sediments, processes and evolution since the Last Glacial Maximum, Geological Society, London, Memoirs, 41, 55–68, https://doi.org/10.1144/m41.6, 2014. 

Violante, R. A., Burone, L., Mahiques, M., and Cavallotto, J. L.: The Southwestern Atlantic Ocean: present and past marine sedimentation, Latin American Journal of Sedimentology and Basin Analysis, 24, 1–5, 2017a. 

Violante, R. A., Cavallotto, J. L., Bozzano, G., and Spoltore, D. V.: Deep marine sedimentation in the Argentine continental margin: Revision and state-of-the-art, Latin American Journal of Sedimentology and Basin Analysis, 24, 7–29, 2017b. 

Voigt, I., Henrich, R., Preu, B. M., Piola, A. R., Hanebuth, T. J. J., Schwenk, T., and Chiessi, C. M.: A submarine canyon as a climate archive — Interaction of the Antarctic Intermediate Water with the Mar del Plata Canyon (Southwest Atlantic), Mar. Geol., 341, 46–57, https://doi.org/10.1016/j.margeo.2013.05.002, 2013. 

Walling, D. E.: The evolution of sediment source fingerprinting investigations in fluvial systems, J. Soil. Sediment., 13, 1658–1675, https://doi.org/10.1007/s11368-013-0767-2, 2013. 

Warratz, G., Schwenk, T., Voigt, I., Bozzano, G., Henrich, R., Violante, R., and Lantzsch, H.: Interaction of a deep-sea current with a blind submarine canyon (Mar del Plata Canyon, Argentina), Mar. Geol., 417, https://doi.org/10.1016/j.margeo.2019.106002, 2019. 

Weldeab, S., Emeis, K.-C., Hemleben, C., and Siebel, W.: Provenance of lithogenic surface sediments and pathways of riverine suspended matter in the Eastern Mediterranean Sea: evidence from 143Nd/144Nd and 87Sr/86Sr ratios, Chem. Geol., 186, 139–149, https://doi.org/10.1016/s0009-2541(01)00415-6, 2002. 

Zembruscki, S. G.: Geomorfologia da margem continental sul brasileira e das bacias oceânicas adjacentes, in: Geomorfologia da margem continental Brasileira e áreas oceânicas adjacentes, edited by: Chaves, H. A. F., REMAC, 7, Petrobrás, Rio de Janeiro, 129–177, 1979 (in Portuguese). 

Download
Short summary
In this work we used a concept called geochemical fingerprinting, with isotopes of neodymium and lead as tools to recognize the main sources and the physical processes responsible for the transport and deposition of sediments on a large area of the South Atlantic margin. Distinct sources, such as Antarctica, the Andean Cordillera, the Río de la Plata basin, and old rocks from the Brazilian shield, are identified.