33 Volcanology (Posters)

Sunday, 9 October 2011
9:00 AM - 6:00 PM
Hall C

MELILITE-BEARING LAPILLI FROM OLDOINYO LENGAI, TANZANIA:EVIDENCE OF CHANGING MINERALOGY WITHIN A SINGLE ERUPTION

Paper number: 33-10
Program: Technical Sessions
Time: 9:00 AM – 6:00 PM

Authors

Abstract

Oldoinyo Lengai in Tanzania is currently the only volcano in the world erupting crabonatitic material. However, Lengai has a long history of explosively erupting silicate material in between effusive eruptions of carbonatites. Liquid immiscibility has been theorized to occur between these two phases. Lapilli from the 2008 summer eruption at Lengai have been collected and mineralogical analysis by x-ray diffraction has revealed the presence of melilite. This appearance of melilite has only occurred a few times at Lengai within recorded time, and analysis of earlier eruptive products in 2007 do not show the presence of melilite. The implications on crystallizing conditions within the magma chamber are presented through textural and mineralogical analysis of the lapilli.