Calc-alkaline volcanic rocks from NW Sardinia: Evaluation of a fractional crystallization model |
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| Authors: | J. Dostal S. Capedri C. A. R. de Albuquerque |
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| Affiliation: | 1. Dept. of Geology, St. Mary’s University, B3H 3C3, Halifax, N. S., Canada
2. 1st. di Mineralogia e Petrologia, Università di Modena, Modena, Italy
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| Abstract: | The volcanic centre of Monte Seda Oro, N. W. Sardinia, representative of a Cenozoic calc-alkaline andesitic suite of rocks is composed of a variety of rocks ranging from high alumina basalts to dacites. The minerals of basaltic, andesitic and dacitic rocks show only limited variation in chemical composition. The geochemical data suggest that the various rock-types are related by a crystal-liquid fractionation. Least-squate numerical calculations, using major element data, support the derivation of andesites with SiO3 content ranging from 53.8 to 59.0% from basalts having about 48.7% of SiO2 by low pressure crystal fractionation of the phenocryst phases present in these rocks. However, the origin of dacites cannot be readily explained by this mechanism. |
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