Phonolite series in North Ethiopia
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| Phonolite Series | |
|---|---|
| Stratigraphic range: | |
 Plug at Addi Amyuq in Dogu’a Tembien | |
| Type | Geological formation |
| Overlies | Tertiary Basalts |
| Lithology | |
| Primary | Phonolite |
| Location | |
| Coordinates | 14°09′29″N 38°56′42″E / 14.158°N 38.945°E |
| Approximate paleocoordinates | 0°N 0°E / 0°N 0°E |
| Region | Tigray |
| Country | Ethiopia |
| Extent | Aksum-Adwa-Dogu’a Tembien |
  Phonolite series in North Ethiopia (Ethiopia) | |
The phonolite or clinkstone of northern Ethiopia is a shallow-seated igneous rock. The phonolites intruded and punctured the Mesozoic sedimentary rocks and the Tertiary flood basalts some 19 to 11 million years ago.[1][2]
The formation occurs as plugs that have punctured the Tertiary flood basalts of the Ethiopian plateau, and form the highest peaks in their surrounding.[1]
Lithology
These phonolites are composed of alkali pyroxenes and nephelines; there are also elongated plagioclase crystals. Pyroxenes have a skeletal texture, whereas nepheline crystals are hexagonal to rectangular.[1][3] The phonolites of pink to light grey colour. The outcrops hold massive (up to 25 metres long), moderately weathered blocks, generally of elongated shape; in some locations it also forms spherical outcrops.[1]
