FN Archimer Export Format
PT J
TI Mineralogy, geochemistry, and Nd isotope composition of the Rainbow hydrothermal field, Mid-Atlantic Ridge
BT 
AF MARQUES, Ana Filipa A.
   BARRIGA, F
   CHAVAGNAC, V
   FOUQUET, Yves
AS 1:1;2:1;3:2;4:3;
FF 1:;2:;3:;4:PDG-DOP-DCB-GM-LGM;
C1 Univ Lisbon, Fac Ciencias, Dept Geol, CREMINER, P-1749016 Lisbon, Portugal.
   Natl Oceanog Ctr, Southampton SO14 3ZH, Hants, England.
   IFREMER, Ctr Brest, F-29280 Plouzane, France.
C2 UNIV LISBON, PORTUGAL
   NATL OCEANOG CTR, ENGLAND
   IFREMER, FRANCE
SI BREST
SE PDG-DOP-DCB-GM-LGM
IN WOS Ifremer jusqu'en 2018
   copubli-europe
IF 1.656
TC 64
UR https://archimer.ifremer.fr/doc/2006/publication-1557.pdf
LA English
DT Article
DE ;Rainbow vent field;Mid Atlantic Ridge;Nd isotope;Serpentinite;Massive sulphide
AB Petrological, geochemical, and Nd isotopic analyses have been carried out on rock samples from the Rainbow vent field to assess the evolution of the hydrothermal system. The Rainbow vent field is an ultramafic-hosted hydrothermal system located on the Mid-Atlantic Ridge characterized by vigorous high-temperature venting (similar to 365 degrees C) and unique chemical composition of fluids: high chlorinity, low pH and very high Fe, and rare earth element (REE) contents (Douville et al., Chemical Geology 184:37-48, 2002). Serpentinization has occurred under a low-temperature (< 270 degrees C) retrograde regime, later overprinted by a higher temperature sulfide mineralization event. Retrograde serpentinization reactions alone cannot reproduce the reported heat and specific chemical features of Rainbow hydrothermal fluids. The following units were identified within the deposit: (1) nonmineralized serpentinite, (2) mineralized serpentinite-stockwork, (3) steatite, (4) semimassive sulfides, and (5) massive sulfides, which include Cu-rich massive sulfides (up to 28wt% Cu) and Zn-rich massive sulfide chimneys (up to 5wt% Zn). Sulfide mineralization has produced significant changes in the sulfide-bearing rocks including enrichment in transition metals (Cu, Zn, Fe, and Co) and light REE, increase in the Co/Ni ratios comparable to those of mafic Cu-rich volcanic-hosted massive sulfide deposits and different Nd-143/Nd-144 isotope ratios. Vent fluid chemistry data are indicative of acidic, reducing, and high temperature conditions at the subseafloor reaction zone where fluids undergo phase separation most likely under subcritical conditions (boiling). An explanation for the high chlorinity is not straightforward unless mixing with high salinity brine or direct contribution from a magmatic Cl-rich aqueous fluid is considered. This study adds new data, which, combined with the current knowledge of the Rainbow vent field, brings compelling evidence for the presence, at depth, of a magmatic body, most likely gabbroic, which provides heat and metals to the system. Co/Ni ratios proved to be good tools used to discriminate between rock units, degree of sulfide mineralization, and positioning within the hydrothermal system. Deeper units have Co/Ni < 1 and subsurface and surface units have Co/Ni > 1.
PY 2006
PD MAY
SO Mineralium Deposita
SN 0026-4598
PU Springer
VL 41
IS 1
UT 000237123600005
BP 52
EP 67
DI 10.1007/s00126-005-0040-8
ID 1557
ER

EF