Cenozoic magmatism on the northern Somali plate: a re-evaluation Daniel MEGE Planetology and Geodynamics Lab, Nantes, France Peter PURCELL P & R Geological Consultants, Scarborough, Australia Fred JOURDAN Western Australia Argon Isotope Facility, Curtin University of Technology, Perth, Australia What is the extent and form of Cenozoic volcanism on the Somali plate? YEMEN VOLCANIC PROVINCE ETHIOPIAN VOLCANIC PROVINCE 30-31 Ma ? Cenozoic volcanic rock exposures 100 km Gulf of Aden AFAR Indian ocean Geologic map of Somalia, 1994 Kenya Geologic map of Ethiopia, 1996 Cenozoic volcanic rock exposures 100 km Gulf of Aden AFAR Indian ocean Geologic map of Somalia, 1994 Kenya Geologic map of Ethiopia, 1996 Data and data sources Field data (and radiochronology) Oil and water wells Aeromagnetic measurements Satellite/aerial imagery Meandering basaltic flows 20 km Meandering basaltic flows 5 km Magnetic meanders ofAthe Bur Acaba High OLIGOCENE OR MIOCENE Quaternary Oligo-Miocene Jurassic Cretaceous B A (Esso, 1984) B Magnetic meanders of eastern Ogaden (Pexco, 2008) buried volcanic meanders Eocene UP. CRET. PALEOC. EOCENE 0m Paleocene 79 m BASALT 122 m EOCENE FLOW 522 m GABBRO 671 m Oligocene volcanics A B EOCENE FLOW? magnetic anomaly (Esso, 1984) A B Water wells in central Somalia which have penetrated basalts Faillace, 1993 Buried basaltic flows A Oil wells that penetrated basalts in the Ogaden and central Somalia B UP. CRET. PALEOC. EOCENE 0m A 79 m BASALT 122 m EOCENE FLOW 522 m GABBRO 671 m Buried basaltic flows OLIGOCENE FLOW B Ogaden Dyke Swarm (Whitestone, 1976, Pexco, 2008) 24.40±0.7 Ma 24.85±0.5 Ma 25.4±0.7 Ma 26.56±0.4 Ma 30±1.9 Ma 20 km DYKE Ogaden Dyke Swarm 400 km Jijiga volcanic plugs (MIOCENE K/Ar) basaltic conglomerate ≥ OLIGOCENE Dolo volcanic field OLIGOCENE dyke swarm OLIGOCENE buried meanders and tabular flows EOCENE meanders Upper OLIGOCENE buried tabular flows OLIGOCENE buried or partly exposed meanders OLIGOCENE volcanic plugs OLIGOCENE (Elf, 1978) Summary Synthesis and perspectives █ … Too early for a synthesis! █ Widespread Oligocene volcanism, evidence of Eocene flows █ Long meandering basaltic flows from Afar (or beyond) in former fluviatile systems █ Evidence of overflow from fluviatile systems : most of the Ogaden and Somalia might have been been flooded by basalts █ A major dyke swarm (400+ km) has been identifed, it is aligned with, and is of age similar to the age of the Red Sea dyke swarm █ Correlations with the volcanism and tectonics of other regions of the Ethio-yemenite LIP remain to be explored!