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Publications


2015

Ichang’i, DW, J.Omenge, Opiyo Akech N.  2015.  Got Ramogi: A Rare Syenitic Intrusion in the Archaean Greenstone Belt of Western Kenya.. African Journal of Science and Technology (AJST) Science and Engineering Series. 13(1):58-67.
Opiyo-Akech, N.  2015.  Environmental and Social Impact Assessment for offshore 2D seismic survey in Puntland Somalia in association with RPS: ION Geoventures; Puntland, Somalia, 2015. : Report for National Environmental Management Authority (NEMA), Kenya
Opiyo-Akech, N.  2015.  Environmental Impact Assessment for the proposed pipeline from Sinendet to Kisumu by KPC: China Petroleum Pipeline Bureau; Sinendet to Kisumu, 2015. : Report for National Environmental Management Authority (NEMA), Kenya
Opiyo-Akech, N.  2015.  Environmental and Social Impact Assessment for proposed exploratory well drilling in Block 11A: CEPSA, Turkana County, 2015. : Report for National Environmental Management Authority (NEMA), Kenya
Opiyo-Akech, N.  2015.  Environmental and Social Impact Assessment for proposed exploratory well drilling in Block L19: Rift Energy, Kwale County, 2015. : Report for National Environmental Management Authority (NEMA), Kenya

2014

Opiyo-Akech, N.  2014.  Environmental and Social Impact Assessment for 2D seismic survey in Block L16: CAMAC Energy.; Kilifi County, 2014. : Report for National Environmental Management Authority (NEMA), Kenya
Opiyo-Akech, N.  2014.  Environmental Impact Assessment for Berilium mining: ARC; Somaliland, 2014. : Report for National Environmental Management Authority (NEMA), Kenya
Opiyo-Akech, N.  2014.  Environmental and Social Impact Assessment for 2D seismic survey in Block 9: Africa Oil B.V. ; Isiolo, Wajir and Marsabit Counties, 2014. : Report for National Environmental Management Authority (NEMA), Kenya
Opiyo-Akech, N.  2014.  Social Impact Assessment for 2D seismic survey in Block 9: Africa Oil B.V.; Wajir County, 2014. : Report for National Environmental Management Authority (NEMA), Kenya
Opiyo-Akech, N.  2014.  Environmental Impact Assessment for an aerodrome in Block 11B: Adamantine Kenya Ltd; Turkana County. Report for National Environmental Management Authority (NEMA), Kenya.

2013

Aketch, ON, Lee H, Fischer TP, Ranka LS, Onguso B, Kanda I, et al.  2013.  Gas Geochemistry of Volcanic and Geothermal Areas in the Kenya Rift: Implications for the Role of Fluids in Continental Rifting. American Geophysical Union, Fall Meeting 2013. AbstractFull Text

The East African Rift (EAR) is an active continental rift and ideal to investigate the processes of rift initiation and the breaking apart of continental lithosphere. Mantle and crust-derived fluids may play a pivotal role in both magmatism and faulting in the EAR. For instance, large quantities of mantle-derived volatiles are emitted at Oldoinyo Lengai volcano [1, 2]. Throughout the EAR, CO2-dominated volatile fluxes are prevalent [3, 4] and often associated with faults (i.e. Rungwe area, Tanzania, [5, 6]). The purpose of this study is to examine the relationship between volcanism, faulting and the volatile compositions, focusing on the central and southern Kenyan and northern Tanzanian section of the EAR. We report our analysis results for samples obtained during a 2013 field season in Kenya. Gases were sampled at fumaroles and geothermal plants in caldera volcanoes (T=83.1-120.2°C) and springs (T=40-79.6°C and pH 8.5-10) located near volcanoes, intra-rift faults, and a transverse fault (the Kordjya fault, a key fluid source in the Magadi rift) by 4N-NaOH solution-filled and empty Giggenbach bottles. Headspace gases were analyzed by a Gas Chromatograph and a Quadrupole Mass Spectrometer at the University of New Mexico. Both N2/Ar and N2/He ratios of all gases (35.38-205.31 and 142.92-564,272, respectively) range between air saturated water (ASW, 40 and ≥150,000) and MORB (100-200 and 40-50). In addition, an N2-Ar-He ternary diagram supports that the gases are produced by two component (mantle and air) mixing. Gases in the empty bottles from volcanoes and springs have N2 (90.88-895.99 mmom/mol), CO2 (2.47-681.21 mmom/mol), CH4 (0-214.78 mmom/mol), O2 (4.47-131.12 mmom/mol), H2 (0-35.78 mmom/mol), Ar (0.15-10.65 mmom/mol), He (0-2.21 mmom/mol), and CO (0-0.08 mmom/mol). Although some of the samples show an atmospheric component, CO2 is a major component in most samples, indicating both volcanoes and springs are emitting CO2. Gases from volcanoes are enriched in CH4 and H2, denoting their sources are reduced (oxygen-poor) magma chambers or hydrothermal systems. 40Ar/36Ar ratios (average of all samples=299.15) are similar to our air standard value (299.65×4.05), however, some volcanoes (~308.75) and springs (~321.96) have slightly higher ratios. The springs with elevated 40Ar imply that both the intra-rift (Lake Bogoria) and transverse (Lake Magadi) faults are possibly pathways to carry volatiles from deep sources to the surface. In future work, we will carry out wet chemistry and ion chromatography analyses of the NaOH solutions, measure 3He/4He ratios and complete C, N, and S isotope analyses to further constrain fluid sources and migration processes. [1] Fischer et al., 2009, Nature 459. [2] de Moor et al., 2013, EPSL 361. [3] Sawyer et al., 2008, G-cubed 9. [4] Tassi et al., 2009, G-cubed 10. [5] Barry et al., 2013, Chem Geol 339. [6] de Moor et al., 2013, Chem Geol 339.

Aketch, ON, Lee L, Chou J, Huang S, Chang S, Wu Y, et al.  2013.  Analyses of the ISUAL Dancing Sprites and Secondary Sprites. American Geophysical Union, Fall Meeting 2013. AbstractFull Text

From July 2004 to May 2012, about 1,700 sprites were recorded by ISUAL (Imager of Sprites and Upper Atmospheric Lightning). Most of them were singly occurring sprites that were not followed by other sprites; while about 7% of them were multi-sprites, which typically start with a sprite and then followed by another sprite that showed a spatial displacement relative to the preceding sprites. Almost all of these events show horizontal shifts between the preceding sprites and the follow-up ones, which previously have been called the dancing sprites. In contrast to the majority cases of dancing sprites with horizontal displacements, three follow-up sprites were found to exhibit a vertical displacement relative to the preceding sprites, which are termed as the secondary sprites in in this report. These three secondary sprites exhibit similar occurring sequences and characteristics; with the preceding clustering sprite spanning the altitudes of ~60-85 km, and then 30 ms or more later, a secondary sprite appears at ~40-65 km altitudes and seems to be connected to the dimming channels of the preceding sprite. From analyzing the spectral and the ULF data, possible generating mechanisms for dancing sprites and secondary sprites are proposed in this report. Several researches [Lyons, 1994; Lyons, 1996; Lu et al., 2012] had indicated that the successive sprite production in the dancing sprites aligned with the lateral leader propagation direction of lightning. We consider that the successively occurring dancing sprites and the secondary sprites are related to the extending leaders of the cloud-to-ground lightning, which are often followed by a continuing current or even a second stroke. The dancing sprites may be induced by the subsequent leaders in the cloud extending mainly in the horizontal direction, while the secondary sprites may be triggered by the leaders extending primarily in the vertical direction. In addition, a numerical quasi-electrostatic (QE) field model is developed with the aim to validate the occurring scenario of the secondary sprites. Based on the information inferred from the associate ULF data of a secondary sprite, salient parameters, including the charge, the charge height, and the discharging time constant, are estimated and used in the QE model calculations. Through performing QE modeling with the ULF inferred parameters, we find that the electric field in the region below the preceding sprites could be enhanced by the continuing current.

Opiyo-Akech, N.  2013.  Environmental Impact Assessment for the proposed Bahasi Aerodrome in block 9 by Africa Oil Kenya B.V. Marsabit County. Report for National Environmental Management Authority (NEMA), Kenya.
Opiyo-Akech, N.  2013.  Environmental Impact Assessment for Adamantine Energy, Block 11B Turkana County. Report for National Environmental Management Authority (NEMA), Kenya.
Opiyo-Akech, N.  2013.  Environmental Monitoring of Seismic Lines in Blocks 10BB and 12A for Tullow Kenya B.V Turkana County. Report for National Environmental Management Authority (NEMA), Kenya.
Opiyo-Akech, N.  2013.  Decommissioning Audit for Lokapel Base Camp for Tullow Kenya B.V. Turkana County. Report for National Environmental Management Authority (NEMA), Kenya.
Opiyo-Akech, N.  2013.  Environmental and Social Impact Assessment for proposed exploratory well drilling in Block 9 for Africa Oil B.V. Wajir County. Report for National Environmental Management Authority (NEMA), Kenya.
Norbert Opiyo Akech*, Masibo{ M, Olago DO.  2013.  Mineral, Oil and Gas Resources. Kenya: A Natural Outlook Geo-Environmental Resources and Hazards. , Oxford, UK: Elsevier
Norbert Opiyo Akech*, Omuombo CA, Masibo{ M.  2013.  General Geology of Kenya. Kenya: A Natural Outlook Geo-Environmental Resources and Hazards. , Oxford, UK: Elsevier Abstract

The geology of Kenya can be divided into five major geological successions:
(1) the Archaean (Nyanzian and Kavirondian), (2) Proterozoic (Mozambique Belt and Bukoban), (3) Palaeozoic/Mesozoic sediments, (4) Tertiary/Quaternary volcanics and sediments, and (5) Pleistocene to Recent soils, alluvial beach sands, evaporites, fossil coral reefs and sandstones at the coast: alluvial and lacustrine sediments of the Rift Valley. There are also volcanic rocks of the Rift Valley from the younger volcanoes.

Oketch, NA, Masibo M, Olago DO.  2013.  Mineral, Oil and Gas Resources. Abstract

The mineral, oil and gas sectors have not played an important role in the economy of Kenya in the past, but the recent discovery of mineral sands and rare earth elements at the coast and oil in the Lokichar Basin in the northern part of the country are proving to be game changers in the mining, oil and gas sectors. The most important minerals mined in the past have been mainly industrial minerals with soda ash and fluorspar being the most important products. Significant tonnage of gold was mined in western parts of Kenya, but currently only minor exploration and production from the old mine sites is taking place. However, with the increased interest and the government resolve to improve mineral exploration, new mineral finds are possible. Exploration for oil and gas has been taking place in Kenya since the 1950s, but it is only recently that significant oil finds have been reported. The findings have inspired several companies to explore for oil and gas within all the major sedimentary basins in Kenya, namely, the Lokichar Basin, Turkana Basin, the Kerio and Baringo Basin, the Anza Basin, and the Lamu Basin.

2005

O, PROFBARONGOJUSTUS, OPIYO PROFAKECHNOBERT.  2005.  Mulwa, J. K., Gaciri, S. J., Opiyo-Akech, N and Kianji, G. K., 2005. Geological and structural influence on groundwater distribution and flow in Ngong area,. Kenya. African Journal of Science and Technology, vol. 6, No. 1, pp. 105-115. : UNIVERSITY OF NAIROBI Abstract
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2002

2001

OPIYO, PROFAKECHNOBERT.  2001.  C.A. Hauzenberger, G. Hoinkes, A.H. Bauernhofer, E. Wallbrecher, H. Fritz, J. Loizenbauer, M. Th. PTt-evolution of Pan- African Granulites in SE-Kenya. EUG 2001.. : UNIVERSITY OF NAIROBI Abstract
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OPIYO, PROFAKECHNOBERT.  2001.  Mining in Kenya: Mining annual review 2001:. Mining Journal Ltd. CD-ROM.. : UNIVERSITY OF NAIROBI Abstract
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2000

Späth, A, Le Roex AP, Opiyo-Akech N.  2000.  The petrology of the Chyulu Hills volcanic province, southern Kenya. AbstractThe petrology of the Chyulu Hills volcanic province, southern Kenya

The Quaternary Chyulu Hills Volcanic Province is located more than 100 km east of the Kenya Rift Valley. It consists of a large number of free-standing and coalesced volcanoes and cinder cones and numerous lava flows ranging in composition from nepheline-normative nephelinites, basanites, alkali basalts and hawaiites to orthopyroxene-normative subalkali basalts. In this paper, the authors briefly outline the geological setting of the Chyulu Hills Volcanic Province, present a classification scheme for its lavas and describe their petrography. Mineral chemistry data for selected olivine and clinopyroxene phenocrysts are presented together with the bulk rock major element compositions of selected samples. The petrography, phenocryst chemistry and bulk rock composition of the typically primitive Chyulu Hills lavas are consistent with a differentiation history dominated by olivine control. A process of delayed olivine fractionation, combined with limited mantle olivine accumulation, is proposed to explain the considerable compositional variability observed among olivine phenocryst cores. A trend of decreasing degree of silica-undersaturation from the oldest lavas, erupted in the northern Chyulu Hills, to progressively younger lavas in the southern part of the province is explained as a result of an age progressive decrease in the depth of melt generation and a coincident increase in the degree of melting.

Aduda, BO, Opiyo N(ed.).  2000.  African Journal of Science and Technology. Website
OPIYO, PROFAKECHNOBERT.  2000.  Spath A., Anton P. le Roex and N. Opiyo-Akech, (2000) - The petrology of the Chyulu hills volcanic Province, Southern Kenya:. Journal of African Earth Sciences, Vol. 31, No. 2., 34-92.. : UNIVERSITY OF NAIROBI Abstract
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MATHU, PROFMUTHUMBIELIUD, MATHU PROFMUTHUMBIELIUD, OPIYO PROFAKECHNOBERT, OPIYO PROFAKECHNOBERT, OPIYO PROFAKECHNOBERT.  2000.  A reappraisal of the geology, structures and tectonics of the Mozambique belt East of the Kenya Rift System. Journ. Afri. Ear. Sci. 30:60.. Kenya and the Pare-Usambara Mts. N.E. Tanzania. Journ. Afr. Eath Sci. 30:10.. : UNIVERSITY OF NAIROBI Abstract
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MATHU, PROFMUTHUMBIELIUD, MATHU PROFMUTHUMBIELIUD, OPIYO PROFAKECHNOBERT.  2000.  Pan African high pressure granulites, Taita Hills - Tsavo East National Park, Kenya. Journ. Afri. Ear. Sci. 30:37.. Kenya and the Pare-Usambara Mts. N.E. Tanzania. Journ. Afr. Eath Sci. 30:10.. : UNIVERSITY OF NAIROBI Abstract
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MATHU, PROFMUTHUMBIELIUD, MATHU PROFMUTHUMBIELIUD, OPIYO PROFAKECHNOBERT.  2000.  Strain and kinematic analysis of major tectonostratigraphic units from the Mozambique Belts of the Voi District, S.E.. Kenya and the Pare-Usambara Mts. N.E. Tanzania. Journ. Afr. Eath Sci. 30:10.. : UNIVERSITY OF NAIROBI Abstract
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OPIYO, PROFAKECHNOBERT.  2000.  Mining in Kenya: Mining annual review 2000:. Mining in Kenya: Mining annual review 2000:. : UNIVERSITY OF NAIROBI Abstract
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OPIYO, PROFAKECHNOBERT.  2000.  Methodology for Image Analysis and Land Cover Classification of Nakuru-Menengai Area (Central Rift Valley, Kenya) .:. African Journal of Science and Technology, Science and Engineering series Vol.1 No.1 pp18 -27. : UNIVERSITY OF NAIROBI Abstract
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1999

Späth, A, Le Roex AP, Opiyo-Akech N.  1999.  Plume-lithosphere Interaction and the Origin of Continental Rift-related Alkaline Volcanism - the Chyulu Hills Volcanic Province, Southern Kenya. AbstractPlume-lithosphere Interaction and the Origin of Continental Rift-related Alkaline Volcanism - the Chyulu Hills Volcanic Province

Geochemical data are presented for primitive alkaline lavas from the Chyulu Hills Volcanic Province of southern Kenya, situated some 100 km east of the Kenya Rift Valley. In addition to their primitive compositions, a striking and ubiquitous feature is a strong but variable depletion in K relative to other highly incompatible elements when normalized to primitive mantle values. Semi-quantitative models are developed that best explain the petrogenesis of these lavas in terms of partial melting of a source that contained residual amphibole (but not phlogopite). The presence of amphibole implies a source in the subcontinental lithosphere rather than the asthenosphere. It is suggested that the amphibole is of metasomatic origin and was precipitated in the lithospheric mantle by infiltrating fluids and/or melts derived from rising mantle plume material. A raised geotherm as a consequence of the continued ascent of the plume material led to dehydration melting of the metasomatized mantle and generation of the Chyulu Hills lavas. It is proposed that the Chyulu Hills Volcanic Province represents an analogue for the earliest stages of continental rift initiation, during which interaction between a plume and initially refractory lithosphere may lead to the generation of lithospheric melts.

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