Three generations of dykes in Wadi Rahma. Cordierite bearing gneiss (800Ma) at the mountain top is intruded by granite (610-615Ma) with synintrusive gently dipping mafic veins (red arrow). This is in turn invaded by composite dykes (green arrow, 570-580Ma) and steep dolerite dykes (blue arrow, 550 Ma). Marker indicates viewpoint of photographer, looking east
PhotoID362
Three generations of dykes in Wadi Rahma. Cordierite bearing gneiss (800Ma) at the mountain top is intruded by granite (610-615Ma) with synintrusive gently dipping mafic veins (red arrow). This is in turn invaded by composite dykes (green arrow, 570-580Ma) and steep dolerite dykes (blue arrow, 550 Ma). Marker indicates viewpoint of photographer, looking east
PhotoID362
Photograph: Cees Passchier, Ghaleb Jarrar