Rare-earth Element Distribution in the Metabasic Rocks of the Land's End Granite Aureole, SW England

P. Mitropoulos
Department of Geology, University of Athens, Panepistimiopolis, Ano Ilisia, Athens 15771, Greece

Abstract: Rock samples from the various metabasic hornfelses of the Land's End granite aureole were analysed for major elements by X-ray fluorescence analysis and for rare-earth elements (REE) by instrumental neutron activation analysis (INAA). The REE patterns of the unaltered dolerites of the area seem to be analogous to those of the alkali basalts, taking into account a slight mobilization of the light REE during low-grade metamorphism.

The REE content of the metabasic rocks of the aureole has increased relative to that of the unaltered dolerites due to the introduction of REE, along with K, from the granite by the action of hydrothermal solutions. The parallel increase in REE with the increase in K is demonstrated.

The metasomatic hornfelses of igneous origin form two groups showing slightly different REE patterns and different rates of increase in REE content. The REE patterns of the two groups show a Eu anomaly increasing with the increase in REE content for the first group and decreasing with the increase in REE content for the second group, A qualitative model of the distribution of the REE in the metabasic aureole rocks is given.

Mineralogical Magazine; December 1984 v. 48; no. 349; p. 495-505; DOI: 10.1180/minmag.1984.048.349.03
© 1984, The Mineralogical Society
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