Salale Mountains
The cone of Salale rises to about 800 m and has a shallow crater. Rocks collected on the northeastern flanks proved to be melanephelinite (Le Bas and Mohr, 1968).
Complete list of alkaline rocks and carbonatites
The cone of Salale rises to about 800 m and has a shallow crater. Rocks collected on the northeastern flanks proved to be melanephelinite (Le Bas and Mohr, 1968).
Wachacha is a well preserved volcanic dome of some 100 km2 centred about 20 km west-southwest of Addis Ababa. The volcano consists of trachytic flows, tuffs, breccias and possible plugs. The trachytes are probably peralkaline.
Mohr (1962a) records the presence of olivine trachytes, phonolitic trachytes, hyalotrachytes, alkaline rhyolites, tuffs and obsidian breccias in the Entotto Hills north of Addis Ababa.
This is a complex rhyolitic volcano overlying older basaltic flows. The rhyolites form a thick sequence of short flows towards the centre. No petrographical or chemical data have been traced but there may be alkaline rocks in the sequence.
This 15 km diameter volcano with a double-rimmed summit caldera consists of basaltic and intermediate lavas culminating in rhyolite flows and breccias. No petrographical or chemical data have been traced but there may be alkaline rocks in the sequence.
This is a large (45 km east-west) twin volcano the older and higher Ayelu centre lying west of Aabida. Ayelu is built of thick rhyolitic flows with the eastern flank covered by ignimbrites that were emitted from Aabida.
Fantale is a strato-volcano 600 m high extending over about 100 km2 and composed predominantly of pantelleritic trachytes and obsidians in which tuffs are subordinate (Gibson, 1970). The summit area is dominated by a 3.5 km diameter caldera with a depth of 300 m.
The Koni volcanic centre is dominated by a series of calderas, eight of which have been identified by Cole (1969), although the earlier ones are much obscured by later volcanic products.
The Boseti volcanic complex is about 20 km in diameter and comprises the two adjacent volcanoes of Gudda and Bariccia both of which are over 2000 m high. Activity has been divided into two cycles (Brotzu et al., 1974 and 1980) with initial volcanism apparently centred on the Gudda centre.
This extensive area southeast of Addis Ababa is wholly occupied by volcanic rocks which fall into four main categories (Gasparon et al., 1993). (1) Early basalts, which are found in linear outcrops along river valleys.