Evidence for the control of the geochemistry of Amazonian floodplain sediments by stratification of suspended sediments in the Amazon

Roddaz, Martín; Viers, Jérôme; Moreira-Turcq, Patrícia; Blondel, Camille; Sondag, Francis; Guyot, Jean‐Loup; Moreira, Luciane Silva

doi:10.1016/j.chemgeo.2014.07.022

Cited by 33 publications

(16 citation statements)

References 47 publications

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“…To supplement classic petrographic approaches based mainly on sand or coarser fractions (e.g., heavy mineral counting; Garzanti et al, ), geochemical provenance proxies are often used, these include major and trace elements (including rare earth element [REE] concentrations), uranium‐lead (U‐Pb) dating of detrital zircons and strontium (Sr)‐neodymium (Nd) isotopic composition of detrital fractions. The results of these methods can be biased by the effect of grain‐size/mineralogical sorting during transport and deposition that may control the geochemical composition of the sediments (Bouchez et al, ; McLennan et al, ; Roddaz et al, ). Despite the robustness of the U‐Pb zircon dating method (Fedo et al, ), this mineral is usually extracted from medium‐to‐coarse grained sandstones, which are more sensitive to sedimentary sorting than fine‐grained sediments (McLennan et al, ).…”

Section: Introductionmentioning

confidence: 99%

Geochemical Evidence for Large‐Scale Drainage Reorganization in Northwest Africa During the Cretaceous

Mourlot

Roddaz

Dera

et al. 2018

Geochem Geophys Geosyst

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West African drainage reorganization during Cretaceous opening of the Atlantic Ocean is deciphered here from geochemical provenance studies of Central Atlantic sediments. Changes in the geochemical signature of marine sediments are reflected in major and trace element concentrations and strontium‐neodymium radiogenic isotopic compositions of Cretaceous sedimentary rocks from eight Deep Sea Drilling Project (DSDP) sites and one exploration well. Homogeneous major and trace element compositions over time indicate sources with average upper (continental) crust signatures. However, detailed information on the ages of these sources is revealed by neodymium isotopes (expressed as ɛNd). The ɛNd(0) values from the DSDP sites show a three‐step decrease during the Late Cretaceous: (1) the Albian‐Middle Cenomanian ɛNd(0) values are heterogeneous (–5.5 to −14.9) reflecting the existence of at least three subdrainage basins with distinct sedimentary sources (Hercynian/Paleozoic, Precambrian, and mixed Precambrian/Paleozoic); (2) during the Late Cenomanian‐Turonian interval, ɛNd(0) values become homogeneous in the deepwater basin (–10.3 to −12.4), showing a negative shift of 2 epsilon units interpreted as an increasing contribution of Precambrian inputs; (3) this negative shift continues in the Campanian‐Maastrichtian (ɛNd(0) = −15), indicating that Precambrian sources became dominant. These provenance changes are hypothesized to be related to the opening of the South and Equatorial Atlantic Ocean, coincident with tectonic uplift of the continental margin triggered by Africa‐Europe convergence. Finally, the difference between ɛNd(0)values of Cretaceous sediments from the Senegal continental shelf and from the deepwater basins suggests that ocean currents prevented detrital material from the Mauritanides reaching deepwater areas.

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Section: Introductionmentioning

confidence: 99%

Geochemical Evidence for Large‐Scale Drainage Reorganization in Northwest Africa During the Cretaceous

Mourlot

Roddaz

Dera

et al. 2018

Geochem Geophys Geosyst

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“…2A). The Al/Si ratio can be considered to represent grain size, as Al is dominant in the clay fraction and Si is the main constituent of quartz, which is the principal mineral in the sand fraction (Bouchez et al, 2011;Roddaz et al, 2014). Heinrich and Zonneveld (2013) found indications for pulses of North Atlantic deep water (NADW) reaching the Ceará Rise from 12.4 Ma onwards, coinciding with the increase in Al/Si in the Ceará Rise sediments.…”

Section: Sedimentation On the Ceará Risementioning

confidence: 99%

“…, 1997 and data references therein). Data from modern Solimões suspended sediments (hexagons) and Madeira (stars) river suspended matter are after Bouchez et al (2011) and Viers et al (2008), Amazon floodplain data after Roddaz et al (2014) and Amazon and Congo River mouth after Bayon et al (2015). Vertical dashed line indicates the cutoff value separating sediment with and Andean provenance from cratonic provenance (after Nie et al, 2012).…”

Section: Figmentioning

confidence: 99%

A 30 Ma history of the Amazon River inferred from terrigenous sediments and organic matter on the Ceará Rise

Soelen

Kim

Santos

et al. 2017

Earth and Planetary Science Letters

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The history of the Amazon River is a much-discussed subject, and the timing of the development of a transcontinental system in particular is a matter of some controversy, with estimations varying between the Early Miocene and the Pliocene or even the Pleistocene. To shed further light on this, we studied the sediment provenance of an Oligocene to Late Pleistocene marine sedimentary section from the Ceará Rise (ODP Site 925), a topographic high in the central Atlantic Ocean, using major element concentrations and Nd isotopic composition in 85 samples. In addition, the carbon isotopic composition of bulk organic matter and changes in the distribution of glycerol dialkyl glycerol tetraethers (GDGTs) were used to identify periods of increased river outflow. On the basis of these results, we suggest that the history of the development of the Amazon River is characterized by specific steps. During the late Oligocene/Early Miocene (30-18.3 Ma), the terrigenous mass accumulation rates (TARs) were high, and sediment and GDGT compositions suggest that a large river system existed, which at times received weathering products from a younger and probably Andean sediment source. A shift to a younger Andean sediment provenance after 8.7 Ma indicates that the Amazon River became permanently connected with the Andes. Between 18.3 and 4.5 Ma, TARs were generally low, and GDGTs were derived for the most part from in situ production in marine waters. Around 4.5 Ma, the river expanded, probably due to ongoing tectonic activity, and uplift in the Andes increased Andean rock erosion. This led to a strong increase in terrigenous sediment deposition and enhanced organic matter preservation on the Ceará Rise, and the delivery of terrestrial (both soil and riverine) branched GDGTs to the Ceará Rise.

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“…However, according to Roddaz et al (2014) the sediments analyzed post-600 years BP have similar chemical and isotopic characteristics to those before the erosive event indicating that that hydrodynamic and climatic changes that have affected the Santa Nina Lake had no influence on the chemical composition of the sediments and did not provoke a drainage reorganization during the last 5600 years.…”

Section: Accepted Manuscriptmentioning

confidence: 94%

“…In Central Amazonia, the Curuai Floodplain is the most extensive flooded region spreading over an area of 3500 km 2 (about 13% of the total flooded area, Maurice-Bourgoin et al, 2007). Some recent studies discussed the control of Amazon River on the geochemistry of Curuai Floodplain sediments (effect on stratification of suspended sediments, Roddaz et al, 2014) and on the floodplain hydrology (Bonnet et al, 2008) and paleohydrology (Moreira et al, 2012). Simultaneously, other studies conducted in Curuai Floodplain have investigated the OM sources and preservation from molecular biomarkers analyses in a sedimentary succession recording the last century , in water column (Mortillaro et al, 2011) and in surface sediments Sobrinho et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Holocene land cover dynamics in the Curuai Floodplain inferred from lacustrine biomarkers

Zocatelli

Jacob

Cordeiro

et al. 2016

Palaeogeography, Palaeoclimatology, Palaeoecology

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International audienceThis study on Curuai Floodplain (Central Amazonia) sediments (last 5600 cal yr BP) focused in Rock‐Eval [RE; hydrogen (HI) and oxygen (OI) indices, Tmax, S2 curve and TpS2], organic petrography and molecular biomarkers [n-alkanes, hopanes, pentacyclic triterpene methyl ethers (PTMEs) and derivatives of pentacyclic triterpenes such as des-A-lupane and aromatic derivatives] analyses. Between 5600 and 5100 cal yr BP, the environment was waterlogged and dominated by emersed plants (Paq 0.27-0.38). The influence of the Amazon River was low. Terrestrial vs aquatic ratio (T/A, ~ 0.8), CPI values (3-4) and high contents of PTME (0.22-1.54 μg/g sed) and aromatics (21-53 μg/g sed) indicated a strong contribution of terrestrial material and anoxic OM deposition conditions. Between 5100 and 5000 cal yr BP more humid conditions due to heavier rainfalls were observed. Early in this period, terrestrial biomarker contents (253 μg/g sed of aromatics, Paq ~ 0.17) increased due to input of watershed erosion material. This provoked a rapid burial and good preservation of terrestrial OM (CPI 3-4.5). From 5000 cal yr BP a strong sedimentation of carbonate minerals (OI ~ 1600 mg CO₂.g^-1) masked the OM signal and affecting RE parameters. Paq (~ 0.18), T/A ratio (~ 0.4) and the decrease of C_31αβ/C_31ββ hopanes (1.18) indicate increasing aquatic conditions up to 2700 cal yr BP. CPI ratio (~ 1.2) and degraded phytoclasts suggest intense degradation during transport to the sedimentation location. The PTMEs results showed that, from 3000 yr cal BP, the Poaceae genuses were different from those found at the bottom (middle-Holocene), suggesting a change of vegetation. The last 600 cal yr BP were marked by the seasonal influence of the Amazon River; during periods of low water level, the organic petrography and CPI values (~ 1.0) evidenced OM degradation and the return of rather drier condition

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Evidence for the control of the geochemistry of Amazonian floodplain sediments by stratification of suspended sediments in the Amazon

Cited by 33 publications

References 47 publications

Geochemical Evidence for Large‐Scale Drainage Reorganization in Northwest Africa During the Cretaceous

Geochemical Evidence for Large‐Scale Drainage Reorganization in Northwest Africa During the Cretaceous

A 30 Ma history of the Amazon River inferred from terrigenous sediments and organic matter on the Ceará Rise

Holocene land cover dynamics in the Curuai Floodplain inferred from lacustrine biomarkers

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