Cenozoic magmatism on the northern Somali plate: a re-evaluation
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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
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What is the extent and form of Cenozoic volcanismon the Somali plate?
ETHIOPIANVOLCANICPROVINCE
YEMEN VOLCANICPROVINCE
?30-31 Ma
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Geologic mapof Somalia, 1994
Geologic mapof Ethiopia, 1996
Cenozoic volcanic rock exposures
AFAR
Gulf of Aden
Indian ocean
100 km
Kenya
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Gulf of Aden
Indian ocean
100 km
AFAR
Kenya
Cenozoic volcanic rock exposures
Geologic mapof Somalia, 1994
Geologic mapof Ethiopia, 1996
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Field data (and radiochronology)
Oil and water wells
Aeromagnetic measurements
Satellite/aerial imagery
Data and data sources
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Fafen
Shebele
Juba
Meandering basaltic flows
20 km
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Fafen
Shebele
Juba
Meandering basaltic flows
5 km
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Magnetic meanders of the Bur Acaba High
Quaternary
Oligo-MioceneCretaceous
Jurassic
B
A
BA
OLIGOCENEOR MIOCENE
(Esso, 1984)
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(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
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Buriedbasaltic flows
Water wells in central Somaliawhich have penetrated basalts
Faillace, 1993
B
A
A BEOCENE FLOW?
magnetic anomaly(Esso, 1984)
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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
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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
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Ogaden Dyke Swarm400 km
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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
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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!