Online citations, reference lists, and bibliographies.
← Back to Search

Quaternary Volcanism And Faulting At O’A Caldera, Central Ethiopian Rift

P. Mohr, J. G. Mitchell, R. Raynolds
Published 1980 · Geology

Save to my Library
Download PDF
Analyze on Scholarcy Visualize in Litmaps
Reduce the time it takes to create your bibliography by a factor of 10 by using the world’s favourite reference manager
Time to take this seriously.
Get Citationsy
O’a is the largest of the Quaternary caldera volcanoes that punctuate the axis of the Ethiopian rift valley. The known volcanic history of O’a is brief: eruptions of restricted ash-flow tuffs and «tufolavas» were followed by extensive pumice deposition with intervening paleosols, lacustrine sediments, and flows of occasional welded tuffs and rare basalts. Ensuing caldera collapse at c. 0.24 m.y. ago was accompanied by emplacement of two massive ignimbrite flow units comprising a single cooling unit: the first was much more severely welded than the second which shows lahar characteristics. Post-caldera volcanism at O’a has been sparse compared with most other Ethiopian rift centres.O’a volcano exemplifies the common rift association of a caldera set tightly between two offset segments of the Wonji fault belt. The Wonji fault belt marks the youngest tectonism of the rift floor, and in the vicinity of O’a has been active in a major way since caldera subsidence. This faulting is clearly younger than the massive rift margin faulting, which to the northeast of O’a occurred during a tectonic climax dated at c. 1.0 m.y. ago.Radiometric analysis suggests a rather regular level of initial40Ar in O’a basalt lavas sampled near to their original vents. If this level also applies to near-vent basalts dated from other parts of the Ethiopian rift, a regional rift paroxysm of crustal extension and related silicic and basaltic volcanism is evident at c. 0.30–0.20 m.y. ago. Episodic dilatation and associated volcano-tectonism separated by long periods of quiescence appears to be a general feature of continental rift valleys.
This paper references
Subaqueous Pyroclastic Flows in the Ohanapecosh Formation, Washington
R. Fiske (1963)
«Tuffolavas» and related formations of central caucasus
E. E. Milanovski (1965)
Chabbi volcano (ethiopia)
P. Mohr (1966)
Laminar Viscous Flowage Structures in Ash-Flow Tuffs from Gran Canaria, Canary Islands
H. Schmincke (1967)
Ignimbrite sequence on Gran Canaria
H. Schmincke (1969)
Gariboldi volcanic complex, Ethiopia
J. W. Cole (1969)
40Ar/36Ar analyses of historic lava flows
G. B. Dalrymple (1969)
A pantelleritic welded ash-flow tuff from the Ethiopian Rift Valley
I. Gibson (1970)
Geology of the Corbetti Caldera area (Main Ethiopian Rift Valley)
G. M. D. Paola (1971)
Prospects for Reykjavic
J. Penrose (1972)
The Chemistry and Petrogenesis of a Suite of Pantellerites from the Ethiopian Rift
Ian L. Girson (1972)
The Ethiopian Rift Valley (between 7° 00′ and 8° 40′ lat. north)
G. D. Paola (1972)
New K/Ar Determinations on Rift Volcanics of S. Kenya and their Bearing on Age of Rift Faulting
J. Fairhead (1972)
Petrological features of boseti mountains, a complex volcanic system in the axial portion of the main Ethiopian rift
P. Brotzu (1974)
Reconnaissance Geology of the Amaro Horst, Southern Ethiopian Rift
Dubi Levitte (1974)
Lake Shala: Water chemistry, mineralogy and geochemistry of sediments in an Ethiopian Rift lake
A. Baumann (1975)
Former Lake Levels and Climatic Change in the Rift Valley of Southern Ethiopia
A. T. Grove (1975)
Volcano spacings and lithospheric attenuation in the Eastern Rift of Africa
P. Mohr (1976)
Formation of Sedimentary Basins of Graben Type by Extension of the Continental Crust
M. P. Bott (1976)
Volcanic stratigraphy and geochronology of the Kedong–Olorgesailie area and the evolution of the South Kenya rift valley
B. H. Baker (1976)
The Sagatu Ridge dike swarm, Ethiopian rift margin. [tectonic evolution]
P. Mohr (1976)
Rift structure in southern Ethiopia
J. M. Moore (1978)
Riftward younging of volcanic units in the Addis Ababa region, Ethiopian rift valley
W. H. Morton (1979)
Global magmatic episodes: New evidence and implications for the steady-state mid-oceanic ridge
P. Vogt (1979)

This paper is referenced by
The Cenozoic magmatism of East Africa: Part II – Rifting of the mobile belt
T. Rooney (2020)
Quantitative Constraints on Faulting and Fault Slip Rates in the Northern Main Ethiopian Rift
M. Siegburg (2020)
Local seismicity near the actively deforming Corbetti volcano in the Main Ethiopian Rift
A. Lavayssière (2019)
Magmatically assisted off-rift extension—The case for broadly distributed strain accommodation
Brandon Chiasera (2018)
Geological evolution of the Boset-Bericha Volcanic Complex, Main Ethiopian Rift: 40 Ar/ 39 Ar evidence for episodic Pleistocene to Holocene volcanism
M. Siegburg (2018)
GIS Based Potential Volcanic Hazard Zonation in Ethiopia the Case of Aluto Volcano
Mesfin Mengistu Mekuria (2018)
Using Lake Sediment Cores to Improve Records of Volcanism at Aluto Volcano in the Main Ethiopian Rift
K. McNamara (2018)
Contrasting styles of post-caldera volcanism along the Main Ethiopian Rift: Implications for contemporary volcanic hazards
K. Fontijn (2018)
Spatially Variable CO2 Degassing in the Main Ethiopian Rift: Implications for Magma Storage, Volatile Transport, and Rift-Related Emissions
Jonathan A. Hunt (2017)
Title : Seismicity associated with magmatism , faulting and hydrothermal circulation at Aluto Volcano , Main Ethiopian Rift
Matthew Wilksa (2017)
Seismicity associated with magmatism, faulting and hydrothermal circulation at Aluto Volcano, Main Ethiopian Rift
M. Wilks (2017)
The eruptive history and magmatic evolution of Aluto volcano : new insights into silicic peralkaline volcanism in the Ethiopian rift
W. Hutchison (2016)
The pattern of emergence of a Middle Stone Age tradition at Gademotta and Kulkuletti (Ethiopia) through convergent tool and point technologies.
Katja Douze (2016)
A pulse of mid-Pleistocene rift volcanism in Ethiopia at the dawn of modern humans
W. Hutchison (2016)
Causes of unrest at silicic calderas in the East African Rift: New constraints from InSAR and soil‐gas chemistry at Aluto volcano, Ethiopia
W. Hutchison (2016)
Structural controls on fluid pathways in an active rift system: A case study of the Aluto volcanic complex
W. Hutchison (2015)
The Geomorphology of the Lake Region (Main Ethiopian Rift): The Record of Paleohydrological and Paleoclimatic Events in an Active Volcano-Tectonic Setting
M. Benvenuti (2015)
Chronological and behavioral contexts of the earliest Middle Stone Age in the Gademotta Formation, Main Ethiopian Rift
Y. Sahle (2014)
39. The Roots of Ash Flow Calderas in Western North America: Windows into the Tops of Granitic Batholiths
C. Series (2014)
Eruptions that Shook the World: Contents
C. Oppenheimer (2011)
Late Quaternary lacustrine ostracoda of the Ziwal | ' rmental indicatorsas Paleoenvlrot
B. Atnafu (2011)
Continental rift evolution: From rift initiation to incipient break-up in the Main Ethiopian Rift, East Africa
G. Corti (2009)
Middle Stone Age (MSA) site distributions in eastern Africa and their relationship to Quaternary environmental change, refugia and the evolution of Homo sapiens
L. Basell (2008)
Temporal geochemical variation in Ethiopian Lakes Shala, Arenguade, Awasa, and Beseka: Possible environmental impacts from underwater and borehole detonations
S. Klemperer (2007)
Eruptions that Shook the World
C. Oppenheimer (2004)
Tensional fissures and crustal extension rates in the northern part of the Main Ethiopian Rift
F. M. Williams (2004)
Elliptic calderas in the Ethiopian Rift: control of pre-existing structures
V. Acocella (2003)
The Ziway Shala lake basin (main Ethiopian rift, Ethiopia): a revision of basin evolution with special reference to the Late Quaternary
M. Benvenuti (2002)
A 300 Million Years History of Rift Lakes in Central and East Africa: An Updated Broad Review
J.-J. Tiercelin (2002)
Gravity Survey of the Shalla Caldera and its Environs for the Exploration of Geothermal Energy
Harbie Hussen (2001)
Volcanism, tectonism, sedimentation, and the paleoanthropological record in the Ethiopian Rift System
G. Woldegabriel (2000)
The Ziway–Shala lake basin system, Main Ethiopian Rift: Influence of volcanism, tectonics, and climatic forcing on basin formation and sedimentation
C. L. Turdu (1999)
See more
Semantic Scholar Logo Some data provided by SemanticScholar