Petrology and geochemistry of the ignimbrites and associated lava domes from N.W. Sardinia |
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| Authors: | C Coulon J Dostal C Dupuy |
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| Institution: | (1) Lab. de Pétrologie, Univ. Saint-Jerôme, F-13397 Marseille Cedex, France;(2) Department of Geology, Saint Mary's University, Halifax, N.S., Canada;(3) Centre Géologique et Géophysique, U.S.T.L., F-34060 Montpellier Cedex, France |
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| Abstract: | Cenozoic calc-alkaline ignimbrites and related lavas from N.W. Sardinia (Italy), which are closely associated with andesites, have dacitic to rhyolitic composition. The ignimbritic rocks underwent fractional crystallization dominated by plagioclase. The model calculations for REE, Ba, Sr, and Rb are consistent with the generation of ignimbritic magmas by partial melting of tonalitic rocks. P-T estimates for the crystallization of ignimbrites, which give temperatures in the range of 910 °–1070 ° C and P
about 5 kb, imply a local increase of temperature in the crust, which is probably related to the ascending andesitic magma. The variations of trace elements indicate that associated andesitic rocks were contaminated by ignimbritic magma. |
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