Cenozoic magmatism on the northern Somali plate:
a re-evaluation
Daniel MEGEPlanetology and Geodynamics Lab, Nantes, France
Peter PURCELLP & R Geological Consultants, Scarborough, Australia
Fred JOURDANWestern Australia Argon Isotope Facility, Curtin University of Technology, Perth, Australia
What is the extent and form of Cenozoic volcanismon the Somali plate?
ETHIOPIANVOLCANICPROVINCE
YEMEN VOLCANICPROVINCE
?30-31 Ma
Geologic mapof Somalia, 1994
Geologic mapof Ethiopia, 1996
Cenozoic volcanic rock exposures
AFAR
Gulf of Aden
Indian ocean
100 km
Kenya
Gulf of Aden
Indian ocean
100 km
AFAR
Kenya
Cenozoic volcanic rock exposures
Geologic mapof Somalia, 1994
Geologic mapof Ethiopia, 1996
Field data (and radiochronology)
Oil and water wells
Aeromagnetic measurements
Satellite/aerial imagery
Data and data sources
Fafen
Shebele
Juba
Meandering basaltic flows
20 km
Fafen
Shebele
Juba
Meandering basaltic flows
5 km
Magnetic meanders of the Bur Acaba High
Quaternary
Oligo-MioceneCretaceous
Jurassic
B
A
BA
OLIGOCENEOR MIOCENE
(Esso, 1984)
(Pexco, 2008)
PaleoceneEocene
Oligocenevolcanics
Magnetic meanders of eastern Ogaden
buried volcanic meanders
GABBRO
BASALT
0 m
79 m
522 m
EOC
ENE
PALE
OC
.U
P. C
RET
.
EOCENEFLOW
122 m
671 m
Buriedbasaltic flows
Water wells in central Somaliawhich have penetrated basalts
Faillace, 1993
B
A
A BEOCENE FLOW?
magnetic anomaly(Esso, 1984)
Buriedbasaltic flows
Oil wells thatpenetratedbasalts in theOgaden andcentral Somalia
A
A
GABBRO
BASALT
0 m
79 m
522 m
EOC
ENE
PALE
OC
.U
P. C
RET
.
EOCENEFLOW
122 m
671 m
OLIGOCENEFLOW
B
B
Ogaden Dyke Swarm(Whitestone, 1976, Pexco, 2008)
DYKE
20 km
24.40±0.7 Ma24.85±0.5 Ma
25.4±0.7 Ma26.56±0.4 Ma
30±1.9 Ma
Ogaden Dyke Swarm400 km
Summary
buried tabular flowsOLIGOCENE
buried meanders andtabular flows EOCENE
dyke swarmOLIGOCENE
Jijiga volcanic plugs(MIOCENE K/Ar)
basalticconglomerate≥ OLIGOCENE
volcanic plugsOLIGOCENE
(Elf, 1978)
Dolo volcanic fieldOLIGOCENE
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!