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A supposed sövite from Oldoinyo Lengai, Tanzania: result of extreme alteration of alkali carbonatite lava

Published online by Cambridge University Press:  05 July 2018

J. B. Dawson
J. B. Dawson*
Affiliation:
Department of Geology and Gcophysics, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW, U.K.
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Abstract

A calcite-rich block in nephelinitic agglomerate at Oldoinyo Lengai comprises Sr-calcite, apatite, fluorite, a Ba-Mn oxide akin to romanrchite, and a distinctive Mn-Fe spinel. Formerly reported as sövite, on textural, mineralogical and stable isotope grounds it is now re-interpreted as a highly-altered natrocarbonatite lava. An implication of this study is that natrocarbonatite is not just a modern phenomenon, but has been extruded from Oldoinyo Lengai for at least around 1250 years.

Keywords

sövitealtered natrocarbonatiteOldoinyo LengaiTanzania
Type
Petrology and Geochemistry
Information
Mineralogical Magazine , Volume 57 , Issue 386 , March 1993 , pp. 93 - 101
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1993

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