African Rift Tectonics and Sedimentation, an Introduction H.G
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The Geothermal Activity of the East African Rift
Presented at Short Course IV on Exploration for Geothermal Resources, organized by UNU-GTP, KenGen and GDC, at Lake Naivasha, Kenya, November 1-22, 2009. Kenya Electricity Generating Co., Ltd. GEOTHERMAL TRAINING PROGRAMME Geothermal Development Company THE GEOTHERMAL ACTIVITY OF THE EAST AFRICAN RIFT Peter A. Omenda Geothermal Development Company P. O. Box 100746, Nairobi 00101 KENYA [email protected] ABSTRACT The East Africa Rift System is a classical continental rift system associated with the world-wide mid ocean rift systems. The rift extends from the Red Sea – Afar triple junction through Ethiopian highlands, Kenya, Tanzania and Malawi to Mozambique in the south. The western branch passes through Uganda, DRC and Rwanda while the nascent south-western branch runs through Luangwa and Kariba rifts in Zambia into Botswana. The volcanic and tectonic activity in the rift started about 30 million years ago and in the eastern branch the activity involved faulting and eruption of large volumes of mafic and silicic lavas and pyroclastics. The western branch, typified by paucity of volcanism, is younger and dominated by faulting that has created deep basins currently filled with lakes and sediments. Geothermal activity in the rift is manifested by the occurrences of Quaternary volcanoes, hotsprings, fumaroles, boiling pools, hot and steaming grounds, geysers and sulphur deposits. The manifestations are abundant and stronger in the eastern branch that encompasses Afar, Ethiopian and Kenya rifts while in the western branch, the activity is subdued and occurs largely as hotsprings and fumaroles. Detailed and reconnaissance studies of geothermal potential in Eastern Africa indicates that the region has potential of 2,500MWe to 6,500MWe. -
Preliminary Catalog of the Sedimentary Basins of the United States
Preliminary Catalog of the Sedimentary Basins of the United States By James L. Coleman, Jr., and Steven M. Cahan Open-File Report 2012–1111 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2012 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Coleman, J.L., Jr., and Cahan, S.M., 2012, Preliminary catalog of the sedimentary basins of the United States: U.S. Geological Survey Open-File Report 2012–1111, 27 p. (plus 4 figures and 1 table available as separate files) Available online at http://pubs.usgs.gov/of/2012/1111/. iii Contents Abstract ...........................................................................................................................................................1 -
Outcomes of the EU Horizon 2020 DAFNE PROJECT the Omo
POLICY BRIEF October 2020 Outcomes of the EU Horizon 2020 DAFNE PROJECT The Omo-Turkana River Basin Progress towards cooperative frameworks KEY POLICY MESSAGES The OTB has reached a stage of pivotal importance for future development; the time to establish a cooperative framework on water governance is now. Transparency and accountability must be improved in order to facilitate the sharing of data and information, increasing trust and reducing the perception of risk. Benefit-sharing which extends beyond energy could enhance regional integration and improve sustainable development within the basin . THE OMO-TURKANA RIVER BASIN potential for hydropower and irrigation schemes that are, if scientifically and equitably managed, crucial to lift millions within and outside the basin out of extreme poverty; this has led to transboundary cooperation in recent years. This policy brief is derived from research conducted under the €5.5M four-year EU Horizon 2020 and Swiss funded ‘DAFNE’ project which concerns the promotion of integrated and adaptive water resources management, explicitly addressing the WEF Nexus and aiming to promote a sustainable economy in regions where new infrastructure and expanding The Omo-Turkana River Basin (OTB) – for the agriculture has to be balanced with social, purposes of the DAFNE Project – comprises of economic and environmental needs. The project two main water bodies: the Omo River in takes a multi- and interdisciplinary approach to Ethiopia and Lake Turkana which it drains into. the formation of a decision analytical While the Omo River lies entirely within Ethiopian territory, Lake Turkana is shared by framework (DAF) for participatory and both Kenya and Ethiopia, with the majority of integrated planning, to allow the evaluation of Lake Turkana residing within Kenya. -
Part 3: Normal Faults and Extensional Tectonics
12.113 Structural Geology Part 3: Normal faults and extensional tectonics Fall 2005 Contents 1 Reading assignment 1 2 Growth strata 1 3 Models of extensional faults 2 3.1 Listric faults . 2 3.2 Planar, rotating fault arrays . 2 3.3 Stratigraphic signature of normal faults and extension . 2 3.4 Core complexes . 6 4 Slides 7 1 Reading assignment Read Chapter 5. 2 Growth strata Although not particular to normal faults, relative uplift and subsidence on either side of a surface breaking fault leads to predictable patterns of erosion and sedi mentation. Sediments will fill the available space created by slip on a fault. Not only do the characteristic patterns of stratal thickening or thinning tell you about the 1 Figure 1: Model for a simple, planar fault style of faulting, but by dating the sediments, you can tell the age of the fault (since sediments were deposited during faulting) as well as the slip rates on the fault. 3 Models of extensional faults The simplest model of a normal fault is a planar fault that does not change its dip with depth. Such a fault does not accommodate much extension. (Figure 1) 3.1 Listric faults A listric fault is a fault which shallows with depth. Compared to a simple planar model, such a fault accommodates a considerably greater amount of extension for the same amount of slip. Characteristics of listric faults are that, in order to maintain geometric compatibility, beds in the hanging wall have to rotate and dip towards the fault. Commonly, listric faults involve a number of en echelon faults that sole into a lowangle master detachment. -
Tracing the Central African Rift and Shear Systems Offshore Onto
Tracing the West and Central African Rift and Shear Systems offshore onto oceanic crust: a ‘rolling’ triple junction William Dickson (DIGs), and James W. Granath, PhD, (Granath & Associates) Abstract Compared to the understood kinematics of its continental margins and adjacent ocean basins, the African continent is unevenly or even poorly known. Consequently, the connections from onshore fault systems into offshore spreading centers and ridges are inaccurately positioned and inadequately understood. This work considers a set of triple junctions and the related oceanic fracture systems within the Gulf of Guinea from Nigeria to Liberia. Our effort redefines the greater Benue Trough, onshore Nigeria, and reframes WCARS (West and Central African Rift and Shear Systems) as it traces beneath the onshore Niger Delta and across the Cameroon Volcanic Line (CVL), Figure 1. We thus join onshore architecture to oceanic fracture systems, forming a kinematically sound whole. This required updating basin outlines and relocating mis- positioned features, marrying illustrations from the literature to imagery suitable for basin to sub- basin mapping. The resulting application of systems structural geology explains intraplate deformation in terms of known structural styles and interplay of their elements. Across the Benue Trough and along WCARS, we infer variations in both structural setting and thermal controls that require further interpretation of their petroleum systems. Introduction Excellent work has defined Africa's onshore geology and the evolution and driving mechanisms of the adjacent (particularly the circum-Atlantic) ocean basins. However, understanding of the oceanic realm has outpaced that of the continent of Africa. This paper briefly reviews onshore work. We then discuss theoretical geometry of tectonic boundaries (including triple junctions) and our data (sources and compilation methods). -
The Mesozoic to Early Cenozoic Magmatism of the Benue Trough (Nigeria); Geochemical Evidence for the Involvement of the St Helen
JOURNAL OF PETROLOGY VOLUME 37 NUMBER 6 PAGES 1341-1358 1996 C. COULON1*, P. VIDAL2, C. DUPUY3, P. BAUDIN1, M. POPOFF*, H. MALUSKI5 AND D. HERMITTE1 'PETROLOGIE MAGMATIQUE, URA 1277, CEREGE, BP 80, 15545 AIX EN PROVENCE CEDEX 4, FRANCE 'CENTRE DE RECHERCHES VOLCANOLOGIQUES, URA 10, 63038 CLERMONT FERRAND CEDEX, FRANCE 'CENTRE GEOLOGIO.UE ET GEOPHYSIO.UE, CNRS, PLACE BATAILLON, J4095 MONTPELLIER CEDEX, FRANCE *INSTITUT DE GEODYNAMIQ.UE, URA 1279, UNIVERSITE DE NICE—SOPHIA ANTIPOLIS, AVENUE EINSTEIN, 06560 VALBONNE, FRANCE JLABORATOIRE DE GEOCHRONOLOGIE—GEOCHIMIE, URA 176J, PLACE BATAILLON, 34095 MONTPELLIER CEDEX, FRANCE The Mesozoic to Early Cenozoic Downloaded from https://academic.oup.com/petrology/article/37/6/1341/1406521 by guest on 28 September 2021 Magmatism of the Benue Trough (Nigeria); Geochemical Evidence for the Involvement of the St Helena Plume The Benue Trough is a continental rift related to the opening of Equatorial Atlantic. Moreover, the geochemical similarity the equatorial domain of the South Atlantic which was initi- between the alkaline magmatism of the Benue Trough and that ated in Late Jurassic-Early Cretaceous times. Highly diversi- of the Cameroon Line suggests that both magmatic provinces fied and volumetrically restricted Mesozoic to Cenozoic were related to the St Helena plume. Finally, the temporal magmatic products are scattered throughout the rift. Three per- change of the mantle sources observed in the Benue Trough can iods of magmatic activity have been recognized on the basis of be accounted for by the recent models of plume dynamics, in the *°Ar-39Ar ages: 147-106 Ma, 97-81 Ma and 68-49 Ma. -
Tectonics of the Musandam Peninsula and Northern Oman Mountains: from Ophiolite Obduction to Continental Collision
GeoArabia, 2014, v. 19, no. 2, p. 135-174 Gulf PetroLink, Bahrain Tectonics of the Musandam Peninsula and northern Oman Mountains: From ophiolite obduction to continental collision Michael P. Searle, Alan G. Cherry, Mohammed Y. Ali and David J.W. Cooper ABSTRACT The tectonics of the Musandam Peninsula in northern Oman shows a transition between the Late Cretaceous ophiolite emplacement related tectonics recorded along the Oman Mountains and Dibba Zone to the SE and the Late Cenozoic continent-continent collision tectonics along the Zagros Mountains in Iran to the northwest. Three stages in the continental collision process have been recognized. Stage one involves the emplacement of the Semail Ophiolite from NE to SW onto the Mid-Permian–Mesozoic passive continental margin of Arabia. The Semail Ophiolite shows a lower ocean ridge axis suite of gabbros, tonalites, trondhjemites and lavas (Geotimes V1 unit) dated by U-Pb zircon between 96.4–95.4 Ma overlain by a post-ridge suite including island-arc related volcanics including boninites formed between 95.4–94.7 Ma (Lasail, V2 unit). The ophiolite obduction process began at 96 Ma with subduction of Triassic–Jurassic oceanic crust to depths of > 40 km to form the amphibolite/granulite facies metamorphic sole along an ENE- dipping subduction zone. U-Pb ages of partial melts in the sole amphibolites (95.6– 94.5 Ma) overlap precisely in age with the ophiolite crustal sequence, implying that subduction was occurring at the same time as the ophiolite was forming. The ophiolite, together with the underlying Haybi and Hawasina thrust sheets, were thrust southwest on top of the Permian–Mesozoic shelf carbonate sequence during the Late Cenomanian–Campanian. -
Plate Tectonics
Plate Tectonics Plate Tectonics is a unifying theory that states that the Earth is composed of lithospheric crustal plates that move slowly, change size, and interact with one another. This theory was amalgamated from a variety of studies that began in the early 20th century and culminated in the 1960s. Early Players: Richard Oldham (1858-1936): discovered P Wave Shadow Zones Inge Lehmann (1888-1993): discovered the S Wave Shadow Zone, including the fact that the outer core is liquid Eduard Suess (1831-1914): published internal structure of the Earth, utilizing some of Oldham’s data Andrija Mohorovicic (1857-1936): discovered the seismic discontinuity between the crust and the mantle Beno Gutenberg (1889-1960): found the CMB to be at 2900 km The Great Synthesizer: Alfred Wagener (1880-1930) Book: The Origin of Continents and Oceans (1915) Found six major pieces of evidence the continents move, hence his theory is known as Continental Drift. (Figures 19.2-1911) 1) The shape of the continents: they fit together 2) Paleontological Evidence: found matching fossils on several continents a) Glossopteris: found in rocks of the same age on South America, South Africa, Australia, India and Antarctica b) Lystrosaurus: found in rocks of the same age on Africa, India, also some in Asia and Antarctica c) Mesosaurus: found in rocks of the same age on South America, South Africa d) Cynognathus: found in rocks of the same age on South America, South Africa 3) Glacial Evidence: the glaciers appear to originate from the modern-day oceans (which is impossible) 4) Structure and Rock Type: geologic features end on one continent and reappear on the other (South America and Africa) 5) Paleoclimate Zones: like today, the old Earth had climate zones. -
The East African Rift System in the Light of KRISP 90
ELSEVIER Tectonophysics 236 (1994) 465-483 The East African rift system in the light of KRISP 90 G.R. Keller a, C. Prodehl b, J. Mechie b,l, K. Fuchs b, M.A. Khan ‘, P.K.H. Maguire ‘, W.D. Mooney d, U. Achauer e, P.M. Davis f, R.P. Meyer g, L.W. Braile h, 1.0. Nyambok i, G.A. Thompson J a Department of Geological Sciences, University of Texas at El Paso, El Paso, TX 79968-0555, USA b Geophysikalisches Institut, Universitdt Karlwuhe, Hertzstrasse 16, D-76187Karlsruhe, Germany ’ Department of Geology, University of Leicester, University Road, Leicester LEl 7RH, UK d U.S. Geological Survey, Office of Earthquake Research, 345 Middlefield Road, Menlo Park, CA 94025, USA ’ Institut de Physique du Globe, Universite’ de Strasbourg, 5 Rue Ret& Descartes, F-67084 Strasbourg, France ‘Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90024, USA ’ Department of Geology and Geophysics, University of Wuconsin at Madison, Madison, WI 53706, USA h Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, IN 47907, USA i Department of Geology, University of Nairobi, P.O. Box 14576, Nairobi, Kenya ’ Department of Geophysics, Stanford University, Stanford, CA 94305, USA Received 21 September 1992; accepted 8 November 1993 Abstract On the basis of a test experiment in 1985 (KRISP 85) an integrated seismic-refraction/ teleseismic survey (KRISP 90) was undertaken to study the deep structure beneath the Kenya rift down to depths of NO-150 km. This paper summarizes the highlights of KRISP 90 as reported in this volume and discusses their broad implications as well as the structure of the Kenya rift in the general framework of other continental rifts. -
Africa-Arabia-Eurasia Plate Interactions and Implications for the Dynamics of Mediterranean Subduction and Red Sea Rifting
This page added by the GeoPRISMS office. Africa-Arabia-Eurasia plate interactions and implications for the dynamics of Mediterranean subduction and Red Sea rifting Authors: R. Reilinger, B. Hager, L. Royden, C. Burchfiel, R. Van der Hilst Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA USA, [email protected], Tel: (617)253 -7860 This page added by the GeoPRISMS office. Our proposed GeoPRISMS Initiative is based on the premise that understanding the mechanics of plate motions (i.e., the force balance on the plates) is necessary to develop realistic models for plate interactions, including processes at subduction and extensional (rifting) plate boundaries. Important advances are being made with new geologic and geophysical techniques and observations that are providing fundamental insights into the dynamics of these plate tectonic processes. Our proposed research addresses directly the following questions identified in the GeoPRISMS SCD Draft Science Plan: 4.2 (How does deformation across the subduction plate boundary evolve in space and time, through the seismic cycle and beyond?), 4.6 (What are the physical and chemical conditions that control subduction zone initiation and the development of mature arc systems?), and 4.7 (What are the critical feedbacks between surface processes and subduction zone mechanics and dynamics?). It has long been recognized that the Greater Mediterranean region provides a natural laboratory to study a wide range of geodynamic processes (Figure 1) including ocean subduction and continent- continent collision (Hellenic arc, Arabia-Eurasia collision), lithospheric delamination (E Turkey High Plateau, Alboran Sea/High Atlas), back-arc extension (Mediterranean basins, including Alboran, Central Mediterranean, Aegean), “escape” tectonics and associated continental transform faulting (Anatolia, North and East Anatolian faults), and active continental and ocean rifting (East African and northern Red Sea rifting, central Red Sea and Gulf of Aden young ocean rifting). -
Lake Turkana and the Lower Omo the Arid and Semi-Arid Lands Account for 50% of Kenya’S Livestock Production (Snyder, 2006)
Lake Turkana & the Lower Omo: Hydrological Impacts of Major Dam & Irrigation Development REPORT African Studies Centre Sean Avery (BSc., PhD., C.Eng., C. Env.) © Antonella865 | Dreamstime © Antonella865 Consultant’s email: [email protected] Web: www.watres.com LAKE TURKANA & THE LOWER OMO: HYDROLOGICAL IMPACTS OF MAJOR DAM & IRRIGATION DEVELOPMENTS CONTENTS – VOLUME I REPORT Chapter Description Page EXECUTIVE(SUMMARY ..................................................................................................................................1! 1! INTRODUCTION .................................................................................................................................... 12! 1.1! THE(CONTEXT ........................................................................................................................................ 12! 1.2! THE(ASSIGNMENT .................................................................................................................................. 14! 1.3! METHODOLOGY...................................................................................................................................... 15! 2! DEVELOPMENT(PLANNING(IN(THE(OMO(BASIN ......................................................................... 18! 2.1! INTRODUCTION(AND(SUMMARY(OVERVIEW(OF(FINDINGS................................................................... 18! 2.2! OMO?GIBE(BASIN(MASTER(PLAN(STUDY,(DECEMBER(1996..............................................................19! 2.2.1! OMO'GIBE!BASIN!MASTER!PLAN!'!TERMS!OF!REFERENCE...........................................................................19! -
Depositional Environment of the Gombe Formation in the Gongola Sub-Basin of the Northern Benue Trough: Using Grain Size Parameters
DOI: http://dx.doi.org/10.4314/gjgs.v15i1.3 GLOBAL JOURNAL OF GEOLOGICAL SCIENCES VOL. 15, 2017: 25-39 COPYRIGHT© BACHUDO SCIENCE CO. LTD PRINTED IN NIGERIA ISSN 1596-6798 25 www.globaljournalseries.com, Email: [email protected] DEPOSITIONAL ENVIRONMENT OF THE GOMBE FORMATION IN THE GONGOLA SUB-BASIN OF THE NORTHERN BENUE TROUGH: USING GRAIN SIZE PARAMETERS M. B. USMAN, Y. D. MAMMAN, U. ABUBAKAR, A. SULAIMAN AND H. HAMIDU (Received 16 June 2016; Revision Accepted 25 July 2016) ABSTRACT The depositional environment of the Gombe Formation was determined using grain size parameters in which sixteen sandstone samples and ninety nine pebbles were subjected to granulometric and pebbles morphometric analysis respectively. The granulometric analysis for the sixteen (16) samples of the Gombe Formation show an average graphic mean of 2.51ϕ (fine grained sandstone), mean standard deviation of 0.58ϕ (moderately well sorted sandstone), mean skewness value of 0.09ϕ (nearly symmetrical) and mean kurtosis value of 0.89ϕ (platykurtic). The Bivariate plot of standard deviation vs. skewness indicated dominance of fluvial environment. While the probability curves plots showed a dominance of three sand populations indicating influence of marine processes. Environmental discrimination formulae for Y1, Y2 and Y3 indicated dominance of Aeolian, shallow agitated marine environment and shallow marine environment respectively. The plots of Y2 vs.Y1 and Y3 vs. Y2 showed a dominance shallow marine environment. The morphometric analysis indicates both fluvial and beach environment with dominance of fluvial environment. KEYWORDS: Gombe Formation, Gongola Sub-Basin, Pebbles Morphology, Granulometric analysis, grain size INTRODUCTION Tukur et al. (2015).