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Petrogenetic mixing models and Nd-Sr isotopic patterns

DePaolo, D. J. and Wasserburg, G. J. (1979) Petrogenetic mixing models and Nd-Sr isotopic patterns. Geochimica et Cosmochimica Acta, 43 (4). pp. 615-627. ISSN 0016-7037. doi:10.1016/0016-7037(79)90169-8.

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The possible Nd and Sr isotopic variations which would result from assimilation of continental crust by mantle-derived magmas can be systematized by considering the chemical and isotopic compositions of the magmas and models for layering within the continental crust. These systematics may provide a valuable framework for studying crustal contamination, the formation of magmas within the crust, and the chemical and age structure of continental segments. The isotopic patterns arise from (1) the overall contrast in Nd and Sr isotopic composition between old continental crust and mantle magma sources, (2) regularities in the variations of ^(143)Nd/^(144)Nd and ^(87)Sr/^(86)Sr in crustal rocks which are related to age and the contrasting geochemical behavior of Sm and Nd relative to Rb and Sr. Consideration of two-component mixing models suggests that the correlation of initial Nd and Sr isotopes in selected young basalts could represent a mixing line, possibly between mantle reservoirs of distinct chemistry and age. However, the possibility that the trend results from mixing of old low - Sm/Nd, high - Rb/Sr crustal material with complementary high - Sm/Nd, low - Rb/Sr mantle reservoirs cannot be eliminated. Such recycling of crust into the mantle could occur in subduction zones. One problem with a recycling model to explain the correlation is that it requires the crustal endmember to have chemical and isotopic properties which do not appear to be common in crustal rocks.

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Wasserburg, G. J.0000-0002-7957-8029
Additional Information:© 1979 Pergamon Press Ltd. Received 13 June 1978; accepted in revised form 4 December 1978. We thank M. T. McCULLOCH for making available unpublished Sm-Nd and Rb-Sr concentration data for incorporation in this paper. We are indebted to C. H. LANGMUIR for a careful review and the associate editor for thoughtful comments which have improved the manuscript. We hope they will forgive us our small deviations. Support from the National Science Foundation EAR 76-22494 is gratefully acknowledged.
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NSFEAR 76-22494
Issue or Number:4
Record Number:CaltechAUTHORS:20131028-155250156
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Official Citation:D.J. DePaolo, G.J. Wasserburg, Petrogenetic mixing models and Nd-Sr isotopic patterns, Geochimica et Cosmochimica Acta, Volume 43, Issue 4, April 1979, Pages 615-627, ISSN 0016-7037, (
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ID Code:42103
Deposited On:29 Oct 2013 17:04
Last Modified:10 Nov 2021 04:38

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