Strontium isotope constraints on fluid flow in the upper oceanic crust at the East Pacific Rise

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doi: 10.1016/j.epsl.2005.01.008
Authors:Gillis, K. M.; Coogan, Laurence A.; Pedersen, R.
Author Affiliations:Primary:
University of Victoria, SEOS, Victoria, BC, Canada
Other:
University of Bergen, Norway
Volume Title:Earth and Planetary Science Letters
Source:Earth and Planetary Science Letters, 232(1-2), p.83-94. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X
Publication Date:2005
Note:In English. Includes appendices. 58 refs.; illus.
Summary:Strontium isotopes are useful tracers of fluid-rock interaction in marine hydrothermal systems and provide a potential way to quantify the amount of seawater that passes through these systems. We have determined the whole-rock Sr-isotopic compositions of a section of upper oceanic crust that formed at the fast-spreading East Pacific Rise, now exposed at Hess Deep. This dataset provides the first detailed comparison for the much-studied Ocean Drilling Program (ODP) drill core from Site 504B. Whole-rock and mineral Sr concentrations indicate that Sr-exchange between hydrothermal fluids and the oceanic crust is complex, being dependent on the mineralogical reactions occurring; in particular, epidote formation takes up Sr from the fluid increasing the 87Sr/86Sr of the bulk-rock. Calculating the fluid-flux required to shift the Sr-isotopic composition of the Hess Deep sheeted-dike complex, using the approach of Bickle and Teagle [1] [M.J. Bickle, D.A.H. Teagle, Strontium alteration in the Troodos ophiolite: implications for fluid fluxes and geochemical transport in mid-ocean ridge hydrothermal systems. Earth Planet. Sci. Lett. 113 (1992) 219-237] gives a fluid-flux similar to that determined for ODP Hole 504B. This suggests that the level of isotopic exchange observed in these two regions is probably typical for modern oceanic crust. Unfortunately, uncertainties in the modeling approach do not allow us to determine a fluid-flux that is directly comparable to fluxes calculated by other methods. Abstract Copyright (2005) Elsevier, B.V.
Sections:Geochemistry
Subsections:Igneous rocks; Oceanic petrology
Subjects:Alkaline earth metals; Basalts; Chemical composition; Chemical reactions; Crust; Diabase; Dikes; Fluid phase; Geochemistry; Geothermal systems; Hydrochemistry; Hydrothermal vents; Igneous rocks; Intrusions; Isotope ratios; Isotopes; Mafic composition; Metals; Mid-ocean ridges; Models; Movement; Ocean Drilling Program; Ocean floors; Oceanic crust; Ophiolite; Petrography; Plate tectonics; Plutonic rocks; Sea-floor spreading; Sr-87/Sr-86; Stable isotopes; Strontium; Textures; Troodos Ophiolite; Volcanic rocks; Volcanism; DSDP Site 504; East Pacific; East Pacific Rise; Equatorial Pacific; Hess Deep; North Pacific; Northeast Pacific; Pacific Ocean
Coordinates:N020000 N022500 W1010000 W1015000
N011335 N011338 W0834348 W0834357
Abstract Numbers:05M/1816
Record ID:2006022128
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands
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