Reports

Temperature Measurements in Carbonatite Lava Lakes and Flows from Oldoinyo Lengai, Tanzania

Science  14 Jul 1989:
Vol. 245, Issue 4914, pp. 168-170
DOI: 10.1126/science.245.4914.168

Abstract

The petrogenesis of carbonatites has important implications for mantle processes and for the magmatic evolution of mantle melts rich in carbon dioxide. Oldoinyo Lengai, Tanzania, is the only active carbonatite volcano on Earth. Its highly alkalic, sodium-rich lava, although different in composition from the more common calcium-rich carbonatites, provides the opportunity for observations of the physical characteristics of carbonatite melts. Temperature measurements on active carbonatitic lava flows and from carbonatitic lava lakes were carried out during a period of effusive activity in June 1988. Temperatures ranged from 491° to 519°C. The highest temperature, measured from a carbonatitic lava lake, was 544°C. These temperatures are several hundred degrees lower than measurements from any silicate lava. At the observed temperatures, the carbonatite melt had lower viscosities than the most fluid basaltic lavas. The unusually low magmatic temperatures were confirmed with 1-atmosphere melting experiments on natural samples.

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