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Science 3 January 1992:
Vol. 255. no. 5040, pp. 72 - 74
DOI: 10.1126/science.255.5040.72
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Articles

Production of Isotopic Variability in Continental Basalts by Cryptic Crustal Contamination

ALLEN F. GLAZNER 1 and G. LANG FARMER 2

1 Department of Geology, University of North Carolina, Chapel Hill, NC 27599
2 Department of Geological Sciences and Cooperative Institute for Research in Environmental Science, University of Colorado, Boulder, CO 80309

Regional variations in the Nd, Sr, and Pb isotopic compositions of Neogene basalts from the western United States are commonly interpreted to originate in the subcontinental mantle. In southern California, isotopic variability is restricted to lavas that lack mantle-derived xenoliths; xenolith-bearing basalts have uniform isotopic compositions similar to those of ocean-island basalts (OIBs). Combined with available geochemical data, these observations suggest that isotopic variability at these volcanoes results from subtle crustal contamination, locally by mafic crust, of primitive OIB-like magma. Recognition of such cryptic contamination may help to reconcile local discrepancies between tectonic and isotopic views of the subcontinental mantle.

Submitted on August 16, 1991
Accepted on October 30, 1991


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Distinguishing Melting of Heterogeneous Mantle Sources from Crustal Contamination: Insights from Sr Isotopes at the Phenocryst Scale, Pisgah Crater, California.
F. C. RAMOS and M. R. REID (2005)
J. Petrology 46, 999-1012
   Abstract »    Full Text »    PDF »
Early extension and associated mafic alkalic volcanism from the southern Basin and Range Province: Geology and petrology of the Rodeo and Nazas volcanic fields, Durango, Mexico.
J. F. Luhr, C. D. Henry, T. B. Housh, J. J. Aranda-Gomez, and W. C. McIntosh (2001)
Geological Society of America Bulletin 113, 760-773
   Abstract »    Full Text »    PDF »
ESTIMATES OF CRUSTAL ASSIMILATION IN QUATERNARY LAVAS FROM THE NORTHERN CORDILLERA, BRITISH COLUMBIA.
J. K. Russell and S. Hauksdottir (2001)
Can Mineral 39, 275-297
   Abstract »    Full Text »    PDF »
Evidence from the Lamarck Granodiorite for Rapid Late Cretaceous Crust Formation in California.
D. S. Coleman, D. S. Coleman, A. F. Glazner, and T. P. Frost (1992)
Science 258, 1924-1926
   Abstract »    PDF »


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