Alkaline Rocks and Carbonatites of the World

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Kowun

stripes

Occurrence number: 
085-00-016
Country: 
Kenya
Location: 
Longitude: 36, Latitude: 1.67

The Kowun volcano forms a low shield overlying basalts and basement gneiss and is itself overlain by Miocene basalts. The shield has a maximum thickness of 300 m and consists principally of trachyte lavas with trachyte pyroclastics, including welded and air fall tuffs, associated with the few eruptive centres. The lavas form flows 30-40 m thick commonly with alkali feldspar phenocrysts up to 1 cm long. The groundmass consists of alkali feldspar laths, interstitial or poikilitic sodic amphibole and aenigmatite, up to 20% modal quartz and rare pyroxene. Two whole rock analyses are in Key (1987b, Table 5).

Age: 
K-Ar on trachyte gave 15.0(3.4 and 15.2(0.2 Ma (Key, 1987b)
References: 
KEY, R.M. 1987b. Geology of the Maralal area. Report, Geological Survey of Kenya, 105: 1-93.
Location: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith