A geochemical study of island-arc and back-arc tholeiites from the Scotia Sea

Elsevier Earth and Planetary Science Letters Volume 36, Issue 2, September 1977, Pages 253-262 Earth and Planetary Science Letters A geochemical study of island-arc and back-arc tholeiites from the Scotia Sea Author links open overlay panel C.J. Hawkesworth 1, R.K. O'Nions 2, R.J. Pankhurst 3, P.J. Hamilton 2, N.M. Evensen 21Department of Earth Sciences, University of Leeds, Leeds Great Britain2Lamont-Doherty Geological Observatory of Columbia University, Palisades, N.Y. 10964USA3British Antarctic Survey, c/o Institute of Geological Sciences, London, WCIX 8N6Great Britain Received 22 April 1977, Revised 9 June 1977, Available online 23 October 2002. Show less https://doi.org/10.1016/0012-821X(77)90207-2Get rights and content Abstract 87Sr/86Sr and143Nd/144Nd ratios, REE and selected minor and trace elements are presented and compared for present-day volcanic rocks in the Scotia Sea. Tholeiitic basalts from the South Sandwich Islands show widely ranging contents of some lithophile elements, e.g. K2O (0.09–0.55%) and Rb (1.55–14.2 ppm), but fairly constant Na2O and Sr. Total REE contents range from about 4–20 times chondritic abundances with significant light-REE depletion and both positive and negative Eu anomalies. The variations in minor and trace element abundances are consistent with low-pressure fractional crystallization of plagioclase and clinopyroxene but only minor amounts of olivine. The87Sr/86Sr and143Nd/144Nd ratios of the parental magmas are thought be 0.7038–0.7039 and 0.51301–0.51314 respectively, and indicate derivation of at least some87Sr from subducted ocean crust. The back-arc tholeiites in the Scotia Sea have lower87Sr/86Sr ratios (0.7028–0.7033), similar143Nd/144Nd ratios (0.51305) and are variably light-REE-enriched(CeN/YbN= 1.0–1.6). Total REE contents are comparable to those of the South Sandwich Islands tholeiites.


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Authors: Hawkesworth, C.J., O'Nions, R.K., Pankhurst, R.J., Hamilton, P.J., Evensen, N.M.

1 January, 1977
Earth and Planetary Science Letters / 36
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