Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences

Olsirwa And Loolmalasin

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Occurrence number: 
163-00-012
Country: 
Tanzania
Location: 
Longitude: 35.8, Latitude: -3.05
Carbonatite: 
No

The overlapping Olsirwa and Loolmalasin volcanoes are built predominantly of basalt lavas, but some phonolite and trachyte occur on the summit ridge of Loolmalasin and basanite within Olsirwa. The small cone of Oldoinyo Wass several kilometres west of Olsirwa is of tephrite. Three analyses of basalt and trachyte, including trace element and Sr, Nd and Pb isotope data, are in Paslick et al. (1995).

References: 

PASLICK, C., HALLIDAY, A.N., JAMES, D. and DAWSON, J.B. 1995. Enrichment of the continental lithosphere by OIB melts: isotopic evidence from the volcanic province of northern Tanzania. Earth and Planetary Science Letters, 130: 109-26.PICKERING, R. 1965. Ngorongoro. Geological Survey of Tanzania, Quarter Degree Sheet, 53.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith