Alkaline Rocks and Carbonatites of the World

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Cacca (Kakka, Kaka)


Occurrence number: 
Main Ethiopian Rift
Longitude: 39.23, Latitude: 7.32

On the key of an unpublished map of Di Paola (1976) this volcano, covering about 18x12 km, is shown as comprising "..pantelleritic ignimbrites associated with mugearitic-alkali and peralkaline trachytic central volcanoes." It has a radial dyke swarm (Mohr, 1980). Mohr (1966a) links it with Chilalo (No. 42) as a "trachyte-carbonatite volcanic centre", but now considers the carbonate rocks are not carbonatitic (P.A. Mohr, pers. comm. 1995). A mugearite described in Le Bas and Mohr (1968) contains aegirine-augite.

K-Ar dating of a trachyte from the northeastern slope gave 2.70 Ma (Woldegabriel et al., 1990) and of an alkali trachyte lava from the summit 3.4(0.4 Ma (Mohr and Potter, 1976).
DI PAOLA, G.M. 1973. The Ethiopian rift valley (between 7°00' and 8°40' lat. north). Bulletin Volcanologique, 36: 517-60.DI PAOLA, G.M. 1976. Geological map of the Tullu Moje' volcanic area (Arussi: Ethiopian rift valley). Consiglio Nazionale delle Ricerche, Italy. (unpublished).LE BAS, M.J. and MOHR, P.A. 1968. Feldspathoidal rocks from the Cainozoic volcanic province of Ethiopia. Geologischer Rundschau, 58: 273-80.MOHR, P.A. 1966a. Geological report on the Lake Langano and adjacent plateau regions. Bulletin of the Geophysical Observatory, Haile Sellassie I University, Addis Ababa, 9: 59-75.MOHR, P. 1980. Geochemical aspects of the Sagatu Ridge dike swarm, Ethiopian rift margin. Accademia Nazionale dei Lincei. Atti dei Convegni Lincei. 47: 387-406.MOHR, P.A. and POTTER, E.C. 1976. The Sagatu Ridge dyke swarms, Ethiopian rift margin. Journal of Volcanology and Geothermal Research, 1: 55-71.WOLDEGABRIEL, G., ARONSON, J.L. and WALTER, R.C. 1990. Geology, geochronology, and rift basin development in the central sector of the Main Ethiopian Rift. Bulletin of the Geological Society of America, 102: 439-58.
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