Genetic significance of chemical,isotopic, and petrographic features of some peralkaline salic rocks from the island of Pantelleria |
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| Authors: | MK Korringa |
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| Institution: | Department of Geology, Stanford University, Stanford, California ,USA; Department of Geological Sciences, Harvard University, Cambridge, Massachusetts ,USA |
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| Abstract: | An anorthoclase phenocryst separate from a pantellerite welded tuff and a slightly peralkaline nonhydrated sodatrachyte glass both have87Sr/86Sr ratios of0.7030 ± 0.0002. The sodatrachyte glass, withSiO2 = 63,Al2O3 = 15.5,and CaO= 1.4wt%and Sr= 53ppm, is interpreted as an intermediate member in the differentiation sequence through which pantellerite melts were derived from primary mafic magmas. The very low87Sr/86Sr ratios, in conjunction with K/Rb ratios of 500 to 700 found for the sodatrachytes, show that the primary mafic magmas were derived from mantle material which had been depleted in incompatible elements by a much earlier episode of magma generation. |
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