Letter | Published:

Age of a new carbonatite locality in northern Kenya


THE ages of carbonatites which occur within the Suregei–Asille Volcanics of northern Kenya cannot be obtained at present by directradioisotope dating, but can be derived from the 40Ar/39Ar K–Ar isochron ages of intercalated felsic ignimbrites. The Suregei–Asille Volcanics crop out over an area of some 1,000 km2 to the north-east of Lake Rudolf. They rest unconformably on the Precambrian basement and comprise several volcanic formations. The rock types include flood basalts; Strombolian cinder cones; aa- and pahaoehoe-flows varying in composition from ankaramitic basalt to trachyte; felsic air-fall and ash-flow deposits; lahars; carbonatite volcanics; and a variety of reworked volcanic ashes, volcaniclastic and fluviatile sediments.

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