FN Archimer Export Format
PT J
TI Rare earth elements and neodymium isotopes in world river sediments revisited
BT 
AF BAYON, Germain
   TOUCANNE, Samuel
   SKONIECZNY, Charlotte
   ANDRE, L.
   BERMELL, Sylvain
   CHERON, Sandrine
   DENNIELOU, Bernard
   ETOUBLEAU, Joel
   FRESLON, Nicolas
   GAUCHERY, T.
   GERMAIN, Yoan
   JORRY, Stephan
   MENOT, G.
   MONIN, L.
   PONZEVERA, Emmanuel
   ROUGET, M. -L.
   TACHIKAWA, K.
   BARRAT, Jean-Alix
AS 1:1,2;2:1;3:1;4:2;5:1;6:1;7:1;8:1;9:1,3;10:1;11:1;12:1;13:4;14:2;15:1;16:3,5;17:4;18:3,5;
FF 1:PDG-REM-GM-LGM;2:PDG-REM-GM-LES;3:;4:;5:PDG-REM-GM-CTDI;6:PDG-REM-GM-LGM;7:PDG-REM-GM-LES;8:PDG-REM-GM-LGM;9:PDG-REM-GM-LGM;10:;11:PDG-REM-GM-LGM;12:PDG-REM-GM-LES;13:;14:;15:PDG-REM-GM-LGM;16:;17:;18:;
C1 IFREMER, Unite Rech Geosci Marines, F-29280 Plouzane, France.
   Royal Museum Cent Afr, Dept Earth Sci, B-3080 Tervuren, Belgium.
   Univ Europeenne Bretagne, F-35000 Rennes, France.
   Univ Aix Marseille, CNRS, CEREGE, IRD,Coll France, F-13545 Aix En Provence 04, France.
   Univ Bretagne Occidentale, CNRS UMS 3113, Inst Univ Europeen Mer, F-29280 Plouzane, France.
C2 IFREMER, FRANCE
   ROYAL MUSEUM CENT AFR, BELGIUM
   UNIV RENNES, FRANCE
   UNIV AIX MARSEILLE, FRANCE
   UBO, FRANCE
SI BREST
SE PDG-REM-GM-LGM
   PDG-REM-GM-LES
   PDG-REM-GM-CTDI
UM LGO
IN WOS Ifremer jusqu'en 2018
   copubli-france
   copubli-europe
   copubli-univ-france
IF 4.315
TC 221
UR https://archimer.ifremer.fr/doc/00276/38733/37249.pdf
LA English
DT Article
AB Over the past decades, rare earth elements (REE) and their radioactive isotopes have received tremendous attention in sedimentary geochemistry, as tracers for the geological history of the continental crust and provenance studies. In this study, we report on elemental concentrations and neodymium (Nd) isotopic compositions for a large number of sediments collected near the mouth of rivers worldwide, including some of the world’s major rivers. Sediments were leached for removal of non-detrital components, and both clay and silt fractions were retained for separate geochemical analyses. Our aim was to re-examine, at the scale of a large systematic survey, whether or not REE and Nd isotopes could be fractionated during Earth surface processes.  Our results confirmed earlier assumptions that river sediments do not generally exhibit any significant grain-size dependent Nd isotopic variability. Most sediments from rivers draining old cratonic areas, sedimentary systems and volcanic provinces displayed similar Nd isotopic signatures in both clay and silt fractions, with ΔεNd (clay-silt) < |1.| A subtle decoupling of Nd isotopes between clays and silts was identified however in a few major river systems (e.g. Nile, Mississippi, Fraser), with clays being systematically shifted towards more radiogenic values. This observation suggests that preferential weathering of volcanic and/or sedimentary rocks relative to more resistant lithologies may occur in river basins, possibly leading locally to Nd isotopic decoupling between different size fractions. Except for volcanogenic sediments, silt fractions generally displayed homogeneous REE concentrations, exhibiting relatively flat shale-normalized patterns. However, clay fractions were almost systematically characterized by a progressive enrichment from the heavy to the light REE and a positive europium (Eu) anomaly. In agreement with results from previous soil investigations, the observed REE fractionation between clays and silts is probably best explained by preferential alteration of feldspars and/or accessory mineral phases. Importantly, this finding clearly indicates that silicate weathering can lead to decoupling of REE between different grain-size fractions, with implications for sediment provenance studies.  Finally, we propose a set of values for a World River Average Clay (WRAC) and Average Silt (WRAS), which provide new estimates for the average composition of the weathered and eroded upper continental crust, respectively, and could be used for future comparison purposes.
PY 2015
PD DEC
SO Geochimica Et Cosmochimica Acta
SN 0016-7037
PU Pergamon-elsevier Science Ltd
VL 170
UT 000364821400002
BP 17
EP 38
DI 10.1016/j.gca.2015.08.001
ID 38733
ER

EF