scholarly journals Evidence for extreme fractionation of peralkaline silicic magmas, the Boseti volcanic complex, Main Ethiopian Rift

2011 ◽  
Vol 104 (3-4) ◽  
pp. 163-175 ◽  
Author(s):  
Ray Macdonald ◽  
Bogusław Bagiński ◽  
Fiorenzo Ronga ◽  
Piotr Dzierżanowski ◽  
Michele Lustrino ◽  
...  
Keyword(s):  
Ethiopian Rift ◽  
Volcanic Complex ◽  
Main Ethiopian Rift ◽  
Silicic Magmas

scholarly journals Geological evolution of the Boset-Bericha Volcanic Complex, Main Ethiopian Rift: 40Ar/39Ar evidence for episodic Pleistocene to Holocene volcanism

2018 ◽  
Vol 351 ◽  
pp. 115-133 ◽  
Author(s):  
Melanie Siegburg ◽  
Thomas M. Gernon ◽  
Jonathan M. Bull ◽  
Derek Keir ◽  
Dan N. Barfod ◽  
...  
Keyword(s):  
Ethiopian Rift ◽  
Volcanic Complex ◽  
Main Ethiopian Rift ◽  
Geological Evolution

scholarly journals Magmatic evolution of the Boku Volcanic Complex, Main Ethiopian Rift

2019 ◽  
Vol 149 ◽  
pp. 109-130 ◽  
Author(s):  
Amdemichael Z. Tadesse ◽  
Dereje Ayalew ◽  
Raphael Pik ◽  
Gezahegn Yirgu ◽  
Karen Fontijn
Keyword(s):  
Ethiopian Rift ◽  
Volcanic Complex ◽  
Magmatic Evolution ◽  
Main Ethiopian Rift

scholarly journals Mapping Hydrothermal Alteration at the Fentale-Dofan Magmatic Segment of the Main Ethiopian Rift

2021 ◽  
Vol 9 ◽  
Author(s):  
Martina Raggiunti ◽  
Derek Keir ◽  
Carolina Pagli
Keyword(s):  
Fluid Flow ◽  
Hydrothermal Alteration ◽  
Hot Springs ◽  
General Pattern ◽  
Hydrothermal Systems ◽  
Tectonic Activity ◽  
Ethiopian Rift ◽  
Volcanic Complex ◽  
Main Ethiopian Rift ◽  
Circular Pattern

The Main Ethiopian Rift (MER) is characterized by extensional tectonics and volcanism, associated with active hydrothermal systems, hydrothermal alteration and fumarolic deposits. The spatial distribution of these hydrothermal products and their link with faults and rock types provides important clues to what controls fluid flow in the subsurface. However, little is known about this in the East African Rift. We address this issue with a multidisciplinary approach in the Fentale-Dofan magmatic segment of the MER, an area characterized by intense volcanic and tectonic activity and a geothermal prospect. Primarily we conduct mapping of hydrothermal alteration and fumarolic deposits, and rock lithologies using a surface feature classification technique of multispectral satellite images. Then we interpret the map using a new database of faults and active hydrothermal manifestations such as hot-springs and fumaroles. We find that the surface hydrothermal alteration and deposits are mainly focused near Fentale and the Dofan Volcanic Complex (DVC). At DVC the hydrothermal products are focused on rhyolites on the western side of the volcano, in an area of intense NNE striking, rift parallel faults. At Fentale volcano the hydrothermal products are mainly associated with ignimbrite and show a circular pattern around the volcanic edifice, but also in places follow the NNE striking faults. At Fentale, the more complex association of hydrothermal products and active manifestations around the edge of the ignimbrite suggests formation contacts may also localize fluid flow in places. At both volcanoes the association between hydrothermal products with either the rhyolites and ignimbrites is likely due to them being relatively easily altered (in comparison to basalt), and also their brittle nature allows for fracturing through which localized fluid flow can occur (as opposed to the sediments). The general pattern of hydrothermal products suggests a stronger structural influence at the DVC with respect to Fentale. The presence of hydrothermal products and active hydrothermal manifestations, along with other lines of evidence such as locus of subsurface dike intrusion at the volcanic centres, suggest that discrete and localized magma reservoirs beneath Fentale and the DVC are the heat source for hydrothermal circulation. Our study also demonstrates that geology, including hydrothermal deposits, can be successfully mapped using automated remote sensing based classification.

Imaging magma storage in the Main Ethiopian Rift with 3-D Magnetotellurics

2020 ◽  
Author(s):  
Juliane Huebert ◽  
Kathy Whaler ◽  
Shimeles Fisseha ◽  
Fiona Iddon ◽  
Colin Hogg
Keyword(s):  
Water Content ◽  
Gravity Data ◽  
Receiver Functions ◽  
Magma Ascent ◽  
Ethiopian Rift ◽  
Volcanic Complex ◽  
Magma Storage ◽  
Energy Potential ◽  
Melt Mixing ◽  
Main Ethiopian Rift

<p>The Main Ethiopian Rift (MER) as part of the large East African continental break-up zone is characterized by lateral extension and active volcanism. Rifting in the MER is magma assisted, with surface expressions of magmatism concentrated at en echelon Quaternary magmatic segments and off-axis linear features, but questions still remain about their respective roles in rifting.</p><p>The storage and pathways of magma ascent are of great interest for the assessment of both geohazard and geothermal energy potential. Imaging magma storage throughout the crust and in the upper mantle can be achieved by geophysical deep sounding techniques such as magnetotellurics (MT). Through MT measurements it is possible to access the electrical conductivity of the subsurface, a parameter that is greatly sensitive to the melt and water content. We present new MT data from the Central MER and a three-dimensional model of conductivity of the crust, imaging across-rift magma storage not only under the well-developed central-axis silicic volcanic complex Aluto, but also under several off-axis basaltic monogenetic volcanic fields. The conductivity model supports the idea of bi-modal magma storage in the CMER and helps constrain the melt and water content in the crust through the use of petrological melt-mixing models. Integrating our findings with the results from seismic tomography and receiver functions as well as Bouguer gravity data and petrological observations allows a comprehensive picture of magma storage and pathways in the MER.</p>

Petrogenesis of a basalt-comendite-pantellerite rock suite: the Boseti Volcanic Complex (Main Ethiopian Rift)

2009 ◽  
Vol 98 (1-4) ◽  
pp. 227-243 ◽  
Author(s):  
Fiorenzo Ronga ◽  
Michele Lustrino ◽  
Andrea Marzoli ◽  
Leone Melluso
Keyword(s):  
Ethiopian Rift ◽  
Volcanic Complex ◽  
Main Ethiopian Rift ◽  
Rock Suite

scholarly journals The effect of hydrogeological and hydrochemical dynamics on landslide triggering in the central highlands of Ethiopia

2021 ◽  
Vol 29 (3) ◽  
pp. 1239-1260
Author(s):  
Tesfay Kiros Mebrahtu ◽  
Andre Banning ◽  
Ermias Hagos Girmay ◽  
Stefan Wohnlich
Keyword(s):  
Hydrostatic Pressure ◽  
Groundwater Flow ◽  
Volcanic Rocks ◽  
Chemical Characterization ◽  
Unconsolidated Sediments ◽  
Ethiopian Rift ◽  
Main Ethiopian Rift ◽  
Groundwater Level Fluctuations ◽  
Landslide Mass ◽  
Landslide Triggering

AbstractThe volcanic terrain at the western margin of the Main Ethiopian Rift in the Debre Sina area is known for its slope stability problems. This report describes research on the effects of the hydrogeological and hydrochemical dynamics on landslide triggering by using converging evidence from geological, geomorphological, geophysical, hydrogeochemical and isotopic investigations. The chemical characterization indicates that shallow to intermediate aquifers cause groundwater flow into the landslide mass, influencing long-term groundwater-level fluctuations underneath the landslide and, as a consequence, its stability. The low content of total dissolved solids and the bicarbonate types (Ca–Mg–HCO3 and Ca–HCO3) of the groundwater, and the dominantly depleted isotopic signature, indicate a fast groundwater flow regime that receives a high amount of precipitation. The main causes of the landslide are the steep slope topography and the pressure formed during precipitation, which leads to an increased weight of the loose and weathered materials. The geophysical data indicate that the area is covered by unconsolidated sediments and highly decomposed and weak volcanic rocks, which are susceptible to sliding when they get moist. The heterogeneity of the geological materials and the presence of impermeable layers embodied within the highly permeable volcanic rocks can result in the build-up of hydrostatic pressure at their interface, which can trigger landslides. Intense fracturing in the tilted basalt and ignimbrite beds can also accelerate infiltration of water, resulting to the build-up of high hydrostatic pressure causing low effective normal stress in the rock mass, giving rise to landslides.

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