Clauer, Norbert et al. (2011): (super 87) Sr/ (super 86) Sr and (super 18) O/ (super 16) O ratios of clays from a hydrothermal area near the Galapagos Rift as records of origin, crystallization temperature and fluid composition
Leg/Site/Hole:
Related Expeditions:
DSDP 54
Identifier:
ID:
2012-014143
Type:
georefid
ID:
10.1016/j.margeo.2011.07.003
Type:
doi
Creator:
Name:
Clauer, Norbert
Affiliation:
Laboratoire d'Hydrologie et de Geochemie de Strasbourg, Strasbourg, France
Role:
author
Name:
O'Neil, James R.
Affiliation:
University of Michigan, United States
Role:
author
Name:
Honnorez, Jose
Affiliation:
Universite de Franche-Comte, France
Role:
author
Name:
Buatier, Martine
Affiliation:
Role:
author
Identification:
Title:
(super 87) Sr/ (super 86) Sr and (super 18) O/ (super 16) O ratios of clays from a hydrothermal area near the Galapagos Rift as records of origin, crystallization temperature and fluid composition
Year:
2011
Source:
Marine Geology
Publisher:
Elsevier, Amsterdam, Netherlands
Volume:
288
Issue:
1-4
Pages:
32-42
Abstract:
Strontium and O isotope compositions of green clay minerals from sediment cores of three boreholes drilled into (sites 424A and 509B) and close to a hydrothermal mound (site 424B) near the Galapagos Spreading Center (DSDP Legs 54 and 70) were determined. The green clays consist mostly of a transition from Fe-smectite (nontronite) to glauconite. (super 87) Sr/ (super 86) Sr ratios were measured on clay size-fractions after gentle acid leaching and on the recovered leachates from different samples. The (super 87) Sr/ (super 86) Sr ratios of the clay residues from both the 424A and B sites are well below the modern seawater value, which points consistently to precipitation from hydrothermal fluids that contained variable amounts of seawater, even away from mound. However, most of the clay residues from mound site 509B have (super 87) Sr/ (super 86) Sr ratios significantly above the seawater value, suggesting the occurrence of a detrital component together with the new authigenic particles. The clay minerals of the hydrothermal mound are mixed with detrital components, and that of the sample taken outside but near the mound as a reference for the surrounding oceanic environment, yields a hydrothermal signature. Crystallization temperatures of the clays range from 32 to 63 degrees C assuming a delta (super 18) O value of +2.2 ppm for the mineralizing fluids. Hydrothermal fluids generated in the underlying oceanic crust, mixed in varied proportions with ambient seawater and migrated into beds of the mound in a sequence of recurrent processes that ultimately resulted in the formation of the observed clay minerals. No significant temperature differences were detected for crystallization of the K-rich glauconite and K-depleted nontronite. The (super 87) Sr/ (super 86) Sr ratios of the Sr leached off the clay particles are near the value of modern seawater, inferring a progressive replacement of the hydrothermal fluids by seawater in the pore space of the mound sediments. Abstract Copyright (2011) Elsevier, B.V.
Language:
English
Genre:
Serial
Rights:
URL:
Coverage: Geographic coordinates: North:0.3538 West:-86.0753 East:
-86.0749 South:0.3521
Keywords: Isotope geochemistry; Oceanography; alkaline earth metals; clastic sediments; clay; clay minerals; cores; crystallization; Deep Sea Drilling Project; DSDP Site 424; DSDP Site 509; East Pacific; Equatorial Pacific; Galapagos Rift; glauconite; hydrothermal vents; IPOD; isotope ratios; isotopes; Leg 54; Leg 70; marine sediments; metals; mica group; nontronite; North Pacific; Northeast Pacific; O-18/O-16; oxygen; Pacific Ocean; Panama Basin; plate tectonics; sediments; sheet silicates; silicates; smectite; Sr-87/Sr-86; stable isotopes; strontium; temperature;
.