FN Archimer Export Format
PT J
TI Comparative geochemistry of four ferromanganese crusts from the Pacific Ocean and significance for the use of Ni isotopes as paleoceanographic tracers
BT 
AF GUEGUEN, Bleuenn
   ROUXEL, Olivier
   ROUGET, Marie-Laure
   BOLLINGER, Claire
   PONZEVERA, Emmanuel
   GERMAIN, Yoan
   FOUQUET, Yves
AS 1:1,2;2:2,4;3:3;4:3;5:2;6:2;7:2;
FF 1:;2:PDG-REM-GM-LCG;3:;4:;5:PDG-REM-GM-LCG;6:PDG-REM-GM-LCG;7:PDG-REM-GM-LCG;
C1 Univ Bretagne Occidentale, UMR 6538, Inst Univ Europeen Mer, F-29280 Plouzane, France.
   IFREMER, Ctr Brest, Unite Geosci Marines, F-29280 Plouzane, France.
   Univ Bretagne Occidentale, UMS 3113, Inst Univ Europeen Mer, F-29280 Plouzane, France.
   Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Dept Oceanog, Honolulu, HI 96822 USA.
C2 UBO, FRANCE
   IFREMER, FRANCE
   UBO, FRANCE
   UNIV HAWAII MANOA, USA
SI BREST
SE PDG-REM-GM-LCG
UM LGO
IN WOS Ifremer jusqu'en 2018
   copubli-france
   copubli-univ-france
   copubli-int-hors-europe
IF 4.609
TC 38
UR https://archimer.ifremer.fr/doc/00341/45255/44696.pdf
LA English
DT Article
CR ZEPOLYF2
BO L'Atalante
DE ;Ferromanganese crusts;Nickel isotopes;Paleoceanography;Pacific Ocean;Biogeochemical cycling
AB Ferromanganese (Fe-Mn) crusts are potential archive of the Ni isotope composition of seawater through time. In this study we aim at (1) understanding Ni isotope fractionation mechanisms and metal enrichment processes in Fe-Mn deposits, (2) addressing global vs. local control of Ni isotope composition of these deposits. Two Fe-Mn crusts from the North Pacific Ocean (Apuupuu Seamount, Hawaii) and two Fe-Mn crusts from the South Pacific Ocean (near Rurutu Island, Austral archipelago of French Polynesia) were characterized for their elemental geochemistry and Ni isotope composition. Geochemical analyses were performed at millimeter intervals in order to provide time-resolved record of Ni isotopes. Chronology and growth rates were determined using cosmogenic 10Be isotope abundances. The results show that, despite different growth rates, textures and geochemical patterns, Fe-Mn crusts from both North and South Pacific Oceans have fairly homogenous Ni isotope compositions over the last ∼17 Ma, yielding average δ60/58Ni values of 1.79 ±0.21 ‰ (2sd, n=31) and 1.73 ±0.21 ‰ (2sd, n=21) respectively. In one crust sample, however, layers directly in contact with the altered substrate show anomalously light δ60/58Ni values down to 0.25 ±0.05 ‰ (2se) together with rejuvenated 10Be/9Be ratios correlating with elevated Ni/Mn ratios. Such patterns are best explained by protracted fluid–rock interactions leading to alteration of Mn-phases after crust formation. Isotopically light Ni is best explained by Ni isotope fractionation during adsorption rather than the contribution of external Ni sources (e.g. hydrothermal sources) having light Ni isotope compositions. The combination of our results with previously published data on Fe-Mn crusts indicates that the average Ni isotope composition in deep waters has not changed through the Cenozoic (∼70 Ma). We propose that Ni isotope variations in Fe-Mn crusts may not only record variations of Ni sources to the oceans, but also post-depositional processes depending on the growth history and geological settings of Fe-Mn crusts.
PY 2016
PD SEP
SO Geochimica Et Cosmochimica Acta
SN 0016-7037
PU Pergamon-elsevier Science Ltd
VL 189
UT 000380753100013
BP 214
EP 235
DI 10.1016/j.gca.2016.06.005
ID 45255
ER

EF