Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published October 1977 | Published
Journal Article Open

The sources of island arcs as indicated by Nd and Sr isotopic studies

Abstract

Island arc lavas from New Britain and the Marianas have ^(143)Nd/^(144)Nd similar to other oceanic basalts and distinctly different from continental flood basalts and thus appear to be derived from a high Sm/Nd, light-REE-depleted reservoir. Consideration of both Nd and Sr isotopes suggests seawater involvement in the generation of some island arc lavas and thus indicates that they may be derived from altered subducted oceanic crust. Other island arc lavas show no evidence of seawater involvement and may be derived from mantle reservoirs with affinities to the sources of ocean island basalts. Andesite and rhyolite from an Andean volcano reflect assimilation of old continental crust. Nd and Sr in basaltic and ultrapotassic continental rocks indicate that some mafic magmas in continental regions may be derived from old low-Sm/Nd reservoirs or are heavily contaminated with old continental crustal material. Fish debris from the ocean floor provides an estimate of ^(143)Nd/^(144)Nd in seawater and indicates that light-REE in the marine environment are derived mainly from continents. Basalts erupted above sea level in oceanic and continental areas are isotopically distinct from those erupted on the ocean floor, suggesting a relationship between parental reservoirs and hydrostatic head.

Additional Information

© 1977 American Geophysical Union. Received July 25, 1977; revised August 23, 1977; accepted September 6, 1977. We are grateful to R. W. Johnson of the Australian Bureau of Mineral Resources for providing carefully selected samples from New Britain and comments on the manuscript. R. J. Stem and F. Barker kindly provided samples from the Marianas, some of which are currently under petrochemical study. We thank I. S. E. Carmichael for petrologic fireside chats and arousing our interest in alkaline lavas with funny names. W. G. Melson provided the Andean samples. We also thank G. Goles for samples of Karroo lavas. Special thanks go to G. Arrhenius who gave us his old teeth. This work has been supported by NSF Grant EAR 76-22494 and NASA Grant NGL 05-002188. Division Contribution No. 2948

Attached Files

Published - grl598.pdf

Files

grl598.pdf
Files (384.7 kB)
Name Size Download all
md5:f0dbdb231d19707c88f65bfdfad657f3
384.7 kB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 25, 2023