FN Archimer Export Format
PT J
TI Controls on the geochemistry of suspended sediments from large tropical South American rivers (Amazon, Orinoco and Maroni)
BT 
AF Rousseau, Tristan C.C.
   Roddaz, Martin
   Moquet, Jean-Sébastien
   Delgado, Helga Handt
   Calves, Gérôme
   Bayon, Germain
AS 1:1,2;2:1;3:3;4:4;5:1;6:5;
FF 1:;2:;3:;4:;5:;6:PDG-REM-GM-LGS;
C1 GET, Université de Toulouse, CNRS-IRD-OMP, 14 avenue Edouard Belin, 31400 Toulouse, France
   LABOMAR- Av. da Abolição, 3207, Fortaleza 60165-081, CE, Brazil
   Institut de Physique du Globe de Paris -, Centre National de la Recherche Scientifique, 1 rue Jussieu, 75005 Paris, France
   Instituto Venezolano de Investigaciones Cientificas, IVIC Centro de Oceanologia y Estudios Antárticos Carretera Panamericana, Km 11. Altos de Pipe 1020ª Venezuela
   IFREMER, Unité de Recherche Géosciences Marines, F-29280 Plouzané, France
C2 UNIV TOULOUSE, FRANCE
   LABOMAR, BRAZIL
   CNRS, FRANCE
   IVIC, VENEZUELA
   IFREMER, FRANCE
SI BREST
SE PDG-REM-GM-LGS
IN WOS Ifremer UPR
   copubli-france
   copubli-univ-france
   copubli-int-hors-europe
   copubli-sud
IF 3.362
TC 27
UR https://archimer.ifremer.fr/doc/00498/60962/64370.pdf
LA English
DT Article
DE ;Major and trace elements;Nd-Sr isotopes;Suspended sediments;Yearly hydrological cycle;Amazon River;Orinoco River;Maroni River
AB We report mineralogical, elemental (major and trace elements) and SrNd isotopic data for suspended particulate matter (SPM) samples from the Amazon, Orinoco and Maroni Rivers collected on a monthly basis over a one-year long hydrological cycle. The aim of this study was i) to characterize the mineralogical and geochemical composition of major South American tropical rivers and ii) to evaluate the effect of seasonal hydroclimate variations and changes in sediment discharge on the composition of these SPM. In addition to displaying particular mineralogical and geochemical signatures (e.g. Al/Si ratios, weathering indices), the Amazon, Orinoco and Maroni SPM are characterized by marked differences in 87Sr/86Sr (0.7213 ± 0.0030, 0.7288 ± 0.0018 and 0.7335 ± 0.0019, respectively), and εNd values (−10.6 ± 0.6, −14.1 ± 0.3 and −23.7 ± 1.2), which reflect differences in source rock lithology. While we find no effect of the hydrological cycle on the geochemistry of Orinoco SPM, particulate εNd and Cr/Th signatures fluctuate with the hydrological cycle in the Maroni basin, indicating that they are controlled by variation in rainfall distribution linked to the latitudinal migration of the Intertropical Convergence Zone (ITCZ). In contrast to Maroni and Orinoco SPM, the Amazon SPM are characterized by significant Sr isotope annual variability correlated with suspended sediments discharge and a small but significant Nd isotopic variability over the year. This latter variation is related to seasonal changes in the rainfall distribution patterns across the Amazon basin, associated with latitudinal migrations of the ITCZ. This suggests that the geochemical composition of the SPM exported over the year from the Amazon Basin faithfully responds to hydroclimate changes related associated with the migration of the rain belt over regions of contrasted geochemical signatures. These findings have implications for the application of Sr and Nd isotopes as provenance proxies in sedimentary archives and paleoclimatic studies. The Sr isotopic composition of exported SPM appears to be mostly controlled by weathering processes and/or mineralogical sorting, rather than being indicative of sediment provenance. In contrast, the relationship documented between Nd isotopes and the hydrological variability indicates that their application to archives of past river sediment discharges can provide unique insights on paleo-hydroclimate changes over tropical South America. 
PY 2019
PD SEP
SO Chemical Geology
SN 0009-2541
PU Elsevier BV
VL 522
UT 000480330600004
BP 38
EP 54
DI 10.1016/j.chemgeo.2019.05.027
ID 60962
ER

EF