DOCSLIB.ORG

Large-Scale Geological Mapping of the Geba Basin, Northern Ethiopia

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Large-Scale Geological Mapping of the Geba Basin, Northern Ethiopia Tigray Livelihood Paper No. 9 Large-Scale Geological mapping of the Geba basin, northern Ethiopia Tesfamichael Gebreyohannes, Florimond De Smedt, Miruts Hagos, Solomon Gebresilassie, Kassa Amare, Kurkura Kabeto, Abdulwassie Hussein, Jan Nyssen, Hans Bauer, Jan Moeyersons, Jozef Deckers, Mitiku Haile, Nurhussen Taha March 2010 VLIR – Mekelle University IUC Program 2 Contents Abstract ......................................................................................................................................................... 5 1. Introduction ............................................................................................................................................... 5 2. Geology of northern Ethiopia ................................................................................................................... 9 2.1 General ............................................................................................................................................... 9 2.2 Flood basalt volcanics ...................................................................................................................... 12 2.3 Amba-Aradam Formation ................................................................................................................. 12 2.4 Antalo Supersequence ...................................................................................................................... 13 2.5 Adigrat Sandstone Formation ........................................................................................................... 14 2.6 Enticho Sandstone and Edaga Arbi Tillites ...................................................................................... 15 2.7 Metamorphic (basement) rocks ........................................................................................................ 17 3. Geological setting of the Geba basin ...................................................................................................... 19 3.1 Quaternary Deposits ......................................................................................................................... 22 3.2 Tertiary Volcanics and Doleritic rocks ............................................................................................. 23 3.2.1 Volcanic rocks ........................................................................................................................... 23 3.2.2 Dolerite sills and dykes ............................................................................................................. 25 3.3 Mesozoic sedimentary rocks............................................................................................................. 26 3.3.1 Upper Sandstone Formation ...................................................................................................... 26 3.3.2 Antalo Supersequence ............................................................................................................... 27 3.3.3 Transitional unit ........................................................................................................................ 29 3.3.4 Lower Sandstone Formation (Adigrat Sandstone) .................................................................... 30 3.4 Paleozoic sedimentary rocks............................................................................................................. 32 3.4.1 Edaga Arbi Tillites .................................................................................................................... 32 3.4.2 Enticho Sandstone ..................................................................................................................... 32 3.5 Precambrian rocks ............................................................................................................................ 33 3.5.1 Granitic Intrusion ...................................................................................................................... 33 3.5.2 Carbonate unit ........................................................................................................................... 34 3.5.3 Slates and Phyllites / Meta-sediments ....................................................................................... 34 3.5.4 Meta-conglomerate .................................................................................................................... 35 3.5.5 Meta-greywacke ........................................................................................................................ 35 3.5.6 Meta-volcanic/volcanoclastic rocks .......................................................................................... 35 4. Structural Setup of the Geba catchment .................................................................................................. 37 4.1 Negash Geosynclinal fold ................................................................................................................. 38 4.2 Foliations and Lineations .................................................................................................................. 39 4.3 Faults and Lineaments ...................................................................................................................... 39 5. Conclusions ............................................................................................................................................. 41 6. References ............................................................................................................................................... 43 3 4 Abstract As part of the groundwater investigation of the Geba basin, a large scale geological mapping campaign was undertaken to identify and characterize the existing lithological units and structural setup. Additional information for the geological mapping was obtained from topographic maps and aerial photographs from the Ethiopian Mapping Agency, and satellite images from the Royal Museum for Central Africa in Tervuren, Belgium. The geology of the basin is divided in to several unites. The basement rock is classified into six units i.e. Intrusive, Meta-sediment, Meta-limestone, Meta-conglomerate, Meta-greywacke, and Meta-volcanic. The Mesozoic sediments are divided in four groups: Upper Sandstone Formation, Antalo Supersequence, Transition unit, and Lower Sandstone Formation. Two units of Paleaozoic sediments are identified: Enticho Sandstone and Edaga Arbi Teillites, and two units of Tertiary igneous rocks: Volcanics and Dolerite dyke/sill. Also two Quaternary deposits are described: Alluvial sediments and Carbonate precipitates. Major geological structures are also mapped and described. The most prominent are the Neoproterozoic Negash Geosyncline folds and foliations, and the Neotectonic Wukro, Mekelle, and Chelekot fault belts. Citation: Tesfamichael G., De Smedt F., Miruts H., Solomon G., Kassa A., Kurkura K., Abdulwassie H., Bauer H., Nyssen J., Moeyersons J., Deckers J., Mitiku H. and Nurhussen T. (2010) Large-scale geological mapping of the Geba basin, northern Ethiopia. Tigray Livelihood Paper No 9, VLIR – Mekelle University IUC Program, 46 pp. ISBN 978-90-8826-134-3 5 6 1. Introduction The Geba basin is one of the least investigated areas in Ethiopia in terms of geological characteristics. Apart from the early days regional geological investigations by the Geological Survey of Ethiopia, there have been some recent investigation mainly focusing on the metamorphic terrains in the northern part of the catchment. Notable research has been made on the basement rocks of the Mai Kinetal and Negash-Hawzen areas by Asrat (1997), Asrat et al. (2001, 2003), Alene (1998), Alene et al. (1999, 2000a, 2000b, 2006), Berhe (1990), Beyth (1972a), Beyth et al. (2003), and Kazmin et al. (1978), and on the sediments of the Mekelle Outlier by Beyth (1972b), Bosellini et al. (1997), Worash and Valera (2001), and Sacchi et al. (2007). Most of these studies focus on the interpretation of the mode of formation and evolution and age of the rocks. To this end many of these studies made geochemical, isotope and paleontological analysis on samples collected from the volcanic, basement, and sedimentary rocks. These investigations have led to some useful information on the geological setting of the region. The geology of northern Ethiopia is further complicated by the abundance of Neoproterozoic to Neotectonic structures such as folds, faults and shear zones, and lineaments. Hence, it is believed that a geological mapping of the Geba basin, which encompasses all types of geological units and the major geological structures of the region, will be of paramount importance for any kind of natural resources investigation and more so for groundwater resources assessment. We have made a major geological mapping campaign of the Geba basin during the period 2005- 2008. The basic objective of this campaign was to describe the various lithological units and to characterize the structural setup of the basin with special emphasis to their role in controlling the groundwater flow and storage. This campaign resulted in a digital geological map (in ArcGIS shape and raster format) describing the lithology and geological structures in the Geba catchment. In order to derive a geological map of the basin, aerial photographs, orthophotos and topographic maps (all on scale 1:50,000) were collected from the Ethiopian Mapping Agency. The 7 topographic maps date from 1996, and are based on aerial photographs taken in 1994. In addition
Load more

Recommended publications
  • Local History of Ethiopia an - Arfits © Bernhard Lindahl (2005)
    Local History of Ethiopia An - Arfits © Bernhard Lindahl (2005) an (Som) I, me; aan (Som) milk; damer, dameer (Som) donkey JDD19 An Damer (area) 08/43 [WO] Ana, name of a group of Oromo known in the 17th century; ana (O) patrikin, relatives on father's side; dadi (O) 1. patience; 2. chances for success; daddi (western O) porcupine, Hystrix cristata JBS56 Ana Dadis (area) 04/43 [WO] anaale: aana eela (O) overseer of a well JEP98 Anaale (waterhole) 13/41 [MS WO] anab (Arabic) grape HEM71 Anaba Behistan 12°28'/39°26' 2700 m 12/39 [Gz] ?? Anabe (Zigba forest in southern Wello) ../.. [20] "In southern Wello, there are still a few areas where indigenous trees survive in pockets of remaining forests. -- A highlight of our trip was a visit to Anabe, one of the few forests of Podocarpus, locally known as Zegba, remaining in southern Wello. -- Professor Bahru notes that Anabe was 'discovered' relatively recently, in 1978, when a forester was looking for a nursery site. In imperial days the area fell under the category of balabbat land before it was converted into a madbet of the Crown Prince. After its 'discovery' it was declared a protected forest. Anabe is some 30 kms to the west of the town of Gerba, which is on the Kombolcha-Bati road. Until recently the rough road from Gerba was completed only up to the market town of Adame, from which it took three hours' walk to the forest. A road built by local people -- with European Union funding now makes the forest accessible in a four-wheel drive vehicle.
    [Show full text]
  • Situation Report EEPA HORN No. 59 - 18 January 2021
    Situation Report EEPA HORN No. 59 - 18 January 2021 Europe External Programme with Africa is a Belgium-based Centre of Expertise with in-depth knowledge, publications, and networks, ​ specialised in issues of peace building, refugee protection and resilience in the Horn of Africa. EEPA has published extensively on issues related to movement and/or human trafficking of refugees in the Horn of Africa and on the Central Mediterranean Route. It cooperates with a wide network of Universities, research organisations, civil society and experts from Ethiopia, Eritrea, Kenya, Djibouti, Somalia, Sudan, South Sudan, Uganda and across Africa. Reported war situation (as confirmed per 17 January) - According to Sudan Tribune, the head of the Sudanese Sovereign Council, Abdel Fattah al-Burhan, disclosed that Sudanese troops were deployed on the border as per an agreement with the Ethiopian Prime Minister, Abiy Ahmed, arranged prior to the beginning of the war. - Al-Burhan told a gathering about the arrangements that were made in the planning of the military actions: “I visited Ethiopia shortly before the events, and we agreed with the Prime Minister of Ethiopia that the Sudanese armed forces would close the Sudanese borders to prevent border infiltration to and from Sudan by an armed party.” - Al-Burhan stated: "Actually, this is what the (Sudanese) armed forces have done to secure the international borders and have stopped there." His statement suggests that Abiy Ahmed spoke with him about the military plans before launching the military operation in Tigray. - Ethiopia has called the operation a “domestic law and order” action to respond to domestic provocations, but the planning with neighbours in the region on the actions paint a different picture.
    [Show full text]
  • Ethiopia Country Office Humanitarian Situation Report Includes Results from Tigray Response
    Ethiopia Country Office Humanitarian Situation Report Includes results from Tigray Response © UNICEF Ethiopia/2021/Nahom Tesfaye Situation in Numbers Reporting Period: May 2021 12.5 million Highlights children in need of humanitarian assistance (HNO 2021) In May, 56,354 new medical consultations were conducted in Afar, Somali and Tigray regions through the 79 UNICEF- supported Mobile Health and Nutrition Teams (MHNTs), 23.5 million 11,692 of these in Tigray through the 30 active MHNTs. people in need UNICEF reached 412,647 people in May and 2,881,630 (HNO 2021) people between January to May 2021 throughout Ethiopia with safe water for drinking, cooking, and personal hygiene 2 through the rehabilitation of non-functional water systems, 3.6 million water treatment, and water trucking; of these, 1,228,921 were internally displaced people (DTM, in Tigray 2021) Since the beginning of the Tigray crisis, UNICEF has delivered 2,352 metric tons of multi-sectoral supplies to nine 806,541 partners (including Regional Bureaus) working in the region, valued at US$ 4.6 million. registered refugees (UNHCR,31 May 2021) In May, UNICEF supported the treatment of 38,032 under 5 children with Severe Acutely Malnutrition (SAM) in Ethiopia (1,723 in Tigray); 40.6 per cent of these were in Oromia, 20.7 per cent in Somali, 15.4 percent in SNNP/Sidama, 12.7 percent in Amhara and 4.5 per cent in Tigray. A total of UNICEF Revised HAC Appeal 152,413 children in the country have been treated for SAM between January – April 2021 with UNICEF direct support 2021
    [Show full text]
  • 000000548.Sbu.Pdf
    SSStttooonnnyyy BBBrrrooooookkk UUUnnniiivvveeerrrsssiiitttyyy The official electronic file of this thesis or dissertation is maintained by the University Libraries on behalf of The Graduate School at Stony Brook University. ©©© AAAllllll RRRiiiggghhhtttsss RRReeessseeerrrvvveeeddd bbbyyy AAAuuuttthhhooorrr... Archaeological Investigation of the Buri Peninsula and Gulf of Zula, Red Sea Coast of Eritrea A Dissertation Presented by Amanuel Yosief Beyin to The Graduate School in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Anthropology (Archaeology) Stony Brook University May 2009 Stony Brook University The Graduate School Amanuel Yosief Beyin We, the dissertation committee for the above candidate for the Doctor of Philosophy degree, hereby recommend acceptance of this dissertation. John J. Shea Associate Professor, Anthropology David J. Bernstein Associate Professor, Anthropology John G. Fleagle Distinguished Professor, Anatomical Sciences Steven A. Brandt Associate Professor, Anthropology University of Florida, Gainesville This dissertation is accepted by the Graduate School Lawrence Martin Dean of the Graduate School ii Abstract of the Dissertation Archaeological Investigation of the Buri Peninsula and Gulf of Zula, Red Sea Coast of Eritrea by Amanuel Yosief Beyin Doctor of Philosophy in Anthropology (Archaeology) Stony Brook University 2009 This dissertation reports the results of archaeological survey and excavations on the Buri Peninsula and Gulf of Zula, Red Sea coast of Eritrea. Its primary goals were to seek evidence for prehistoric human settlement, and to define the geological, chronological and cultural contexts of the sites. The Red Sea Coast of Africa is thought to be an important refugium for humans dispersing from the interior of East Africa into Arabia and the Levant.
    [Show full text]
  • 20210714 Access Snapshot- Tigray Region June 2021 V2
    ETHIOPIA Tigray: Humanitarian Access Snapshot (July 2021) As of 31 July 2021 The conflict in Tigray continues despite the unilateral ceasefire announced by the Ethiopian Federal Government on 28 June, which resulted in the withdrawal of the Ethiopian National Overview of reported incidents July Since Nov July Since Nov Defense Forces (ENDF) and Eritrea’s Defense Forces (ErDF) from Tigray. In July, Tigray forces (TF) engaged in a military offensive in boundary areas of Amhara and Afar ERITREA 13 153 2 14 regions, displacing thousands of people and impacting access into the area. #Incidents impacting Aid workers killed Federal authorities announced the mobilization of armed forces from other regions. The Amhara region the security of aid Tahtay North workers Special Forces (ASF), backed by ENDF, maintain control of Western zone, with reports of a military Adiyabo Setit Humera Western build-up on both sides of the Tekezi river. ErDF are reportedly positioned in border areas of Eritrea and in SUDAN Kafta Humera Indasilassie % of incidents by type some kebeles in North-Western and Eastern zones. Thousands of people have been displaced from town Central Eastern these areas into Shire city, North-Western zone. In line with the Access Monitoring and Western Korarit https://bit.ly/3vcab7e May Reporting Framework: Electricity, telecommunications, and banking services continue to be disconnected throughout Tigray, Gaba Wukro Welkait TIGRAY 2% while commercial cargo and flights into the region remain suspended. This is having a major impact on Tselemti Abi Adi town May Tsebri relief operations. Partners are having to scale down operations and reduce movements due to the lack Dansha town town Mekelle AFAR 4% of fuel.
    [Show full text]
  • Starving Tigray
    Starving Tigray How Armed Conflict and Mass Atrocities Have Destroyed an Ethiopian Region’s Economy and Food System and Are Threatening Famine Foreword by Helen Clark April 6, 2021 ABOUT The World Peace Foundation, an operating foundation affiliated solely with the Fletcher School at Tufts University, aims to provide intellectual leadership on issues of peace, justice and security. We believe that innovative research and teaching are critical to the challenges of making peace around the world, and should go hand-in- hand with advocacy and practical engagement with the toughest issues. To respond to organized violence today, we not only need new instruments and tools—we need a new vision of peace. Our challenge is to reinvent peace. This report has benefited from the research, analysis and review of a number of individuals, most of whom preferred to remain anonymous. For that reason, we are attributing authorship solely to the World Peace Foundation. World Peace Foundation at the Fletcher School Tufts University 169 Holland Street, Suite 209 Somerville, MA 02144 ph: (617) 627-2255 worldpeacefoundation.org © 2021 by the World Peace Foundation. All rights reserved. Cover photo: A Tigrayan child at the refugee registration center near Kassala, Sudan Starving Tigray | I FOREWORD The calamitous humanitarian dimensions of the conflict in Tigray are becoming painfully clear. The international community must respond quickly and effectively now to save many hundreds of thou- sands of lives. The human tragedy which has unfolded in Tigray is a man-made disaster. Reports of mass atrocities there are heart breaking, as are those of starvation crimes.
    [Show full text]
  • Partners' Guide to Ethiopia
    PARTNERS’ GUIDE TO ETHIOPIA Africa Avenue, one of the main streets in Addis Ababa. One of the main streets in Addis Ababa. Welcome Statement from Dennis Weller Mission Director, USAID Ethiopia Mission Director Dennis Weller USAID/Ethiopia Dear Reader, If you’ve opened this guide, you have already As the home of the African Union and the United demonstrated an interest in development Nations Economic Commission for Africa, Addis opportunities in Ethiopia. That is an important Abeba is already the diplomatic hub of Africa. first step. Assuming Ethiopia continues on its current development track, it has the potential to become Boasting one of the highest GDP growth rates an economic hub. in the world over the past decade, Ethiopia is certainly on the rise. The Government of Ethiopia All of us at the United States Agency for was instrumental in leading that growth and International Development in Ethiopia (USAID) now has ambitious plans to move Africa’s second would like to encourage potential investors to most populous country and one of its poorest to look at the opportunities which Ethiopia offers middle-income status by 2025. In support of that and to consider investing if it makes sense. As a goal, it is investing heavily in its infrastructure and development agency, we like to say that our goal social services. is to one day work ourselves out of a job. That day may still be some way off in Ethiopia, but we’re For our part, USAID’s development portfolio optimistic that the growing involvement of the consists of a wide range of activities designed private sector in Ethiopia’s development will help to create opportunities for Ethiopian citizens.
    [Show full text]
  • Hydrological Response to Land Cover and Management (1935-2014) in a Semi-Arid Mountainous Catchment of Northern Ethiopia
    i Copyright: Etefa Guyassa 2017 Published by Department of Geography – Ghent University Krijgslaan 281 (S8), 9000 Gent (Belgium) © All rights reserved iii Faculty of Science Etefa Guyassa Hydrological response to land cover and management (1935-2014) in a semi-arid mountainous catchment of northern Ethiopia Proefschrift voorgelegd tot het behalen van de graad van Doctor in de Wetenschappen: Geografie 2016-2017 v Cover: view of Mekelle. Black and white photograph (1935) by © Istituto Luce Cinecittà vii Promoter Prof. dr. Jan Nyssen, Ghent University Co-promoters Prof. dr. Jean Poesen, Division of Geography and Tourism, Faculty of Sciences, KU Leuven, Belgium Dr. Amaury Frankl, Department of Geography, Faculty of Sciences, Ghent University, Belgium Member of the Jury Prof. Dr. Ben Derudder, Department of Geography, Faculty of Sciences, Ghent University, Belgium (chair) Prof. Dr. Veerle Van Eetvelde, Department of Geography, Faculty of Sciences, Ghent University, Belgium Prof. Dr. Matthias Vanmaercke, Department of Geography, Faculty of Sciences, University of Liege, Belgium Prof. Dr. Charles Bielders, Earth and Life Institute, Faculty of Biosciences Engineering, Université Catholique de Louvain, Belgium Prof. Dr. Rudi Goossens, Department of Geography, Faculty of Sciences, Ghent University, Belgium Prof. Dr. Sil Lanckriet, Department of Geography, Faculty of Sciences, Ghent University, Belgium Dean Prof. dr. Herwig Dejonghe Rector Prof. dr. Anne De Paepe ix Scientific citation: Scientific citation: Etefa Guyassa, 2017. Hydrological response to land cover and management (1935-2014) in a semi-mountainous catchment of northern Ethiopia. PhD thesis. Department of Geography, Ghent University, Belgium. xi Acknowledgements It is my pleasure to acknowledge several people and organizations for their contribution to this study.
    [Show full text]
  • Geology, Geochronology, and Rift Basin Development in the Central Sector of the Main Ethiopia Rift
    Geology, geochronology, and rift basin development in the central sector of the Main Ethiopia Rift GIDAY WOLDEGABRIEL* ) n „ „, JAMES L ARONSON J DePartment °J Geological Sciences, Case Western Reserve University, Cleveland, Ohio 44106 ROBERT C. WALTER Institute of Human Origins, 2453 Ridge Road, Berkeley, California 94709 ABSTRACT 37°30'-40°. A satellite thematic mapper image of this classic rift region (Fig. 1) shows all but the southwestern part of the study area. The MER is Based on stratigraphic relationships and K/Ar dating of volcanic divided geographically into three sectors: northern, central, and southern rocks from both of the escarpments, flanking plateaus, and from the (inset map, Fig. 2), and most of the central sector of the rift proper is in this rift floor of the central sector of the Main Ethiopian Rift, six major image. The MER divides the 1,000-km-wide uplifted Ethiopian volcanic volcanic episodes are recognized in the rift's development over a time province asymmetrically into the northwest and southeast plateaus (inset span from the late Oligocene to the Quaternary. Using the K/Ar data, map, Fig. 2). Volcanic sequences that cover an area several hundred correlation of volcanic units from the six periods of activity through- kilometers across are more voluminous and widespread on the northwest out the study area forms the basis for establishing six time- plateau than on the opposite side. Contrary to previous suggestions that stratigraphic chronozones for the central sector that are related to volcanism migrated from the northwest plateau toward the Ethiopian Rifts volcanism in the Ethiopian Cenozoic volcanic province.
    [Show full text]
  • Detrital Zircon U–Pb Geochronology Of
    Precambrian Research 154 (2007) 88–106 Detrital zircon U–Pb geochronology of Cryogenian diamictites and Lower Paleozoic sandstone in Ethiopia (Tigrai): Age constraints on Neoproterozoic glaciation and crustal evolution of the southern Arabian–Nubian Shield D. Avigad a,∗, R.J. Stern b,M.Beythc, N. Miller b, M.O. McWilliams d a Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel b Geosciences Department, University of Texas at Dallas, Richardson, TX 75083-0688, USA c Geological Survey of Israel, 30 Malkhe Yisrael Street, Jerusalem 95501, Israel d Department of Geological and Environmental Sciences, Stanford University, CA 94305-2115, USA Received 1 May 2006; received in revised form 11 December 2006; accepted 14 December 2006 Abstract Detrital zircon geochronology of Neoproterozoic diamictites and Ordovician siliciclastics in northern Ethiopia reveals that the southern Arabian–Nubian Shield (ANS) formed in two major episodes. The earlier episode at 0.9–0.74 Ga represents island arc volcanism, whereas the later phase culminated at 0.62 Ga and comprised late to post orogenic granitoids related to crustal differ- entiation associated with thickening and orogeny accompanying Gondwana fusion. These magmatic episodes were separated by about ∼100 my of reduced igneous activity (a magmatic lull is detected at about 0.69 Ga), during which subsidence and deposition of marine carbonates and mudrocks displaying Snowball-type C-isotope excursions (Tambien Group) occurred. Cryogenian diamictite interpreted as glacigenic (Negash synclinoria, Tigrai) and polymict conglomerates and arkose of possible peri-glacial origin (Shiraro area, west Tigrai), deformed and metamorphosed within the Neoproterozoic orogenic edifice, occur at the top of the Tambien Group.
    [Show full text]
  • Groundwater in Ethiopia
    Springer Hydrogeology Groundwater in Ethiopia Features, Numbers and Opportunities Bearbeitet von Seifu Kebede 1. Auflage 2012. Buch. xiv, 283 S. Hardcover ISBN 978 3 642 30390 6 Format (B x L): 15,5 x 23,5 cm Gewicht: 613 g Weitere Fachgebiete > Geologie, Geographie, Klima, Umwelt > Geologie > Hydrologie, Hydrogeologie Zu Inhaltsverzeichnis schnell und portofrei erhältlich bei Die Online-Fachbuchhandlung beck-shop.de ist spezialisiert auf Fachbücher, insbesondere Recht, Steuern und Wirtschaft. Im Sortiment finden Sie alle Medien (Bücher, Zeitschriften, CDs, eBooks, etc.) aller Verlage. Ergänzt wird das Programm durch Services wie Neuerscheinungsdienst oder Zusammenstellungen von Büchern zu Sonderpreisen. Der Shop führt mehr als 8 Millionen Produkte. Chapter 2 Groundwater Occurrence in Regions and Basins 2.1 The Broad (Oligo-Miocene) Volcanic Plateau and Associated Shields Geology and Stratigraphy The broad volcanic plateau (Fig. 1.2) accounts for about 25 % of Ethiopian land- mass. The Ethiopian volcanic plateau is a thick monotonous, rapidly erupted pile of locally deformed, flat lying basalts consisting of a number of volcanic centers with different magmatic character and with a large range of ages. The trap volcanics including the associated shield volcanoes cover an area at least 6 9 105 km2 (around two-third surface of the country), and a total volume estimated to be at least 3.5 9 105 km3 (Mohr 1983) and probably higher than 1.2 9 106 km3 according to Rochette et al. (1998). Flat-topped hills and nearly horizontal lava flows is a common scene in the broad volcanic plateau. Topographic features of the basaltic plateau are vertical cliffs, waterfalls, V-shaped valleys, vertical and mushroom-like outcrops of columnar basalts, and step-like hill terraces.
    [Show full text]
  • Provenance of Sandstones in Ethiopia During
    1 Provenance of sandstones in Ethiopia during Late 2 Ordovician and Carboniferous–Permian Gondwana 3 glaciations: petrography and geochemistry of the Enticho 4 Sandstone and the Edaga Arbi Glacials 5 6 Anna Lewina,*, Guido Meinholdb,c, Matthias Hinderera, Enkurie L. Dawitd, 7 Robert Busserte 8 9 aInstitut für Angewandte Geowissenschaften, Fachgebiet Angewandte 10 Sedimentologie, Technische Universität Darmstadt, Schnittspahnstraße 9, 11 64287 Darmstadt, Germany 12 bAbteilung Sedimentologie / Umweltgeologie, Geowissenschaftliches 13 Zentrum Göttingen, Universität Göttingen, Goldschmidtstraße 3, 37077 14 Göttingen, Germany 15 cSchool of Geography, Geology and the Environment, Keele University, 16 Keele, Staffordshire, ST5 5BG, UK 17 dDepartment of Geology, University of Gondar, P.O. Box 196, Gondar, 18 Ethiopia 19 eInstitut für Angewandte Geowissenschaften, Fachgebiet 20 Explorationsgeologie, Technische Universität Berlin, Ackerstraße 76, 13355 21 Berlin, Germany 22 23 *corresponding author. Tel. +49 6151 1620634 24 E-mail address: [email protected] (A. Lewin). 25 26 27 Abstract 28 29 We compare Ethiopian glaciogenic sandstone of the Late Ordovician 30 and Carboniferous–Permian Gondwana glaciations petrographically 31 and geochemically to provide insight into provenance, transport, and 32 weathering characteristics. Although several studies deal with the 33 glacial deposits in northern Africa and Arabia, the distribution of ice 34 sheets and continent-wide glacier dynamics during the two 35 glaciations remain unclear. Provenance data on Ethiopian Palaeozoic 36 sedimentary rocks are scarce. The sandstones of the Late Ordovician 37 glaciation are highly mature with an average quartz content of 95% 1 38 and an average chemical index of alteration of 85, pointing to intense 39 weathering and reworking prior to deposition.
    [Show full text]