The Chemistry and Petrogenesis of a Suite of Pantellerites from the Ethiopian Rift |
| |
Authors: | GIRSON IAN L |
| |
Institution: | Department of Earth Sciences, The University of Leeds
1 Present address: Department of Geology, Bedford College, University of London, London, N.W.I. |
| |
Abstract: | Data on the major and trace element chemistry of a suite oftwenty pantelleritic pitchstone lavas from the Quaternary Ethiopianvolcano Fantale is presented. This reveals a contrast betweenthe composition of the pre-caldera flows and the more siliceous,less peralkaline post-caldera lavas. Comparison with experimental and theoretical studies suggeststhat nearly all of the major and trace element variation withinthe two suites can be explained by assuming fractional crystallizationof alkali-feldspar, the most abundant phenocryst phase. Fractionationof the mafic phases appears to have been less significant. The trace element data strongly indicate that the lavas allbelong to a single suite. However, it is suggested that themajor element chemistry of the post-caldera flows was modifiedby the loss of volatiles at the time of the formation of thecaldera, an event which coincided with the eruption of a 2 km3welded ash-flow tuff. |
| |
Keywords: | |
本文献已被 Oxford 等数据库收录! |
|