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Girum B, Chekol T, Meshesha D. Petrological and geochemical characteristics of flood and shield basalts from Kesem-Megezez section, northwestern Ethiopian Plateau: Implication for their mantle source variations. Heliyon 2023; 9:e17256. [PMID: 37389036 PMCID: PMC10300378 DOI: 10.1016/j.heliyon.2023.e17256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 06/10/2023] [Accepted: 06/12/2023] [Indexed: 07/01/2023] Open
Abstract
The Kesem-Megezez Section is located on the western escarpment of the main Ethiopian rift, central Ethiopia, part of the northwestern Ethiopia plateau, and hosts both flood basalts (Kesem Oligocene basalts) and shield volcano basalts (Megezez Miocene basalts) separated by an Oligo-Miocene silicic pyroclastic formation. Petrography, whole-rock trace, and major element data are presented for the Kesem Oligocene and Megezez Miocene basalts to assess their petrogenetic characteristics and the processes involved in their evolution. The Kesem Oligocene basalts are dominated by aphanitic textures, whereas the Megezez Miocene basalts are dominated by porphyritic textures. The Kesem Oligocene basalts are alkaline, whereas the Megezez Miocene basalts have transitional composition. The Kesem Oligocene basalts and Megezez Miocene basalts show distinct compositional differences. MREE/HREE and LREE/HREE show different depths of melt segregation and degrees of partial melting for the Kesem Oligocene basalts and the Megezez Miocene basalts. The geochemical differences (Zr/Nb, Rb/Zr, K/Nb, Ba/Zr and Nb/Zr) between Kesem alkaline basalts and the Megezez transitional basalts reflect the involvement of EMORB-like and OIB-like mantle sources in different proportion in their petrogenesis. Using primitive mantle, garnet- and spinel-bearing lherzolitic sources, a non-modal equilibrium melting model shows that the Kesem alkali basalt can be produced by equilibrium melting of ∼3-4% residual garnet and about 3% degree of partial melting. Whereas, the Megezez transitional basalts were formed by melting of ∼2-3% residual garnet and >3% degree of partial melting. Geochemical evidences envisioned a scenario in which magmatism started with the arrival of a mantle plume (OIB-like; aka Afar Plume), which comes across a sub-lithospheric geochemically enriched and fertile asthenospheric mantle component (EMORB-like). The upwelling of the hot mantle plume that impinging beneath the lithiosphere at ∼30 Ma generates OIB-type melts due to decompression. The thermal effect of the hot plume also triggered melting of the fertile E-MORB component in the asthenosphere at the garnet stability depth. Then, the interaction between more melts from the plume (OIB) and lesser melts from the E-MORB created flood basalts (Kesem basalts) in the Oligocene. During the Miocene, the progressive melting of OIB and E-MORB generates the plateau shield basalts (Megezez basalts).
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Affiliation(s)
- Birhane Girum
- Department of Geology, College of Applied Sciences, Addis Ababa Science and Technology University, P.O. Box 16417, Addis Ababa, Ethiopia
- Mineral Exploration, Extraction and Processing Center of Excellence, Addis Ababa Science and Technology University, P.O. Box 16417, Addis Ababa, Ethiopia
| | - Takele Chekol
- Department of Geology, College of Applied Sciences, Addis Ababa Science and Technology University, P.O. Box 16417, Addis Ababa, Ethiopia
- Mineral Exploration, Extraction and Processing Center of Excellence, Addis Ababa Science and Technology University, P.O. Box 16417, Addis Ababa, Ethiopia
| | - Daniel Meshesha
- Department of Geology, College of Applied Sciences, Addis Ababa Science and Technology University, P.O. Box 16417, Addis Ababa, Ethiopia
- Mineral Exploration, Extraction and Processing Center of Excellence, Addis Ababa Science and Technology University, P.O. Box 16417, Addis Ababa, Ethiopia
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2
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Zhang L, Cao Z, Zartman RE, Li C, Sun S, Liu L, Sun W. An emerging plume head interacting with the Hawaiian plume tail. Innovation (N Y) 2023; 4:100404. [PMID: 36915900 PMCID: PMC10005903 DOI: 10.1016/j.xinn.2023.100404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 02/16/2023] [Indexed: 02/24/2023] Open
Abstract
The Hawaiian-Emperor seamount chain has shown two subparallel geographical and geochemical volcanic trends, Loa and Kea, since ∼5 Ma, for which numerous models have been proposed that usually involve a single mantle plume sampling different compositional sources of the deep or shallow mantle. However, both the dramatically increased eruption rate of the Hawaiian hotspot since ∼5 Ma and the nearly simultaneous southward bending of the Hawaiian chain remain unexplained. Here, we propose a plume-plume interaction model where the compositionally depleted Kea trend represents the original Hawaiian plume tail and the relatively enriched Loa trend represents an emerging plume head southeast of the Hawaiian plume tail. Geodynamic modeling further suggests that the interaction between the existing Hawaiian plume tail and the emerging Loa plume head is responsible for the southward bending of the Hawaiian chain. We show that the arrival of the new plume head also dramatically increases the eruption rate along the hotspot track. We suggest that this double-plume scenario may also represent an important mechanism for the formation of other hotspot tracks in the Pacific plate, likely reflecting a dynamic reorganization of the lowermost mantle.
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Affiliation(s)
- Lipeng Zhang
- Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.,Laboratory for Marine Geology, Laoshan Laboratory, Qingdao 266237, China
| | - Zebin Cao
- Department of Geology, University of Illinois at Urbana-Champaign, Urbana, IL 61820, USA
| | - Robert E Zartman
- Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Congying Li
- Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.,Deep-Sea Multidisciplinary Research Center, Laoshan Laboratory, Qingdao 266237, China
| | - Saijun Sun
- Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.,Laboratory for Marine Geology, Laoshan Laboratory, Qingdao 266237, China
| | - Lijun Liu
- Department of Geology, University of Illinois at Urbana-Champaign, Urbana, IL 61820, USA
| | - Weidong Sun
- Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.,Deep-Sea Multidisciplinary Research Center, Laoshan Laboratory, Qingdao 266237, China.,University of the Chinese Academy of Sciences, Beijing 100049, China
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Meshesha D, Chekol T, Negussia S. Major and trace element compositions of basaltic lavas from western margin of central main Ethiopian rift: enriched asthenosphere vs. mantle plume contribution. Heliyon 2021; 7:e08634. [PMID: 35005282 PMCID: PMC8715302 DOI: 10.1016/j.heliyon.2021.e08634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 10/22/2021] [Accepted: 12/15/2021] [Indexed: 11/26/2022] Open
Abstract
Major and trace element data are presented for basaltic lavas from western rift margin of central Main Ethiopian Rift located at Kella area to investigate the processes involved in the petrogenesis of the erupted magmas and the nature of mantle source compositions. Kella area is composed of Quaternary (<1.6 Ma), Miocene (10.6–8.3 Ma) and Oligocene basalts (30-29 Ma) ranging from alkaline to tholeiitic in composition. The geochemical variations of basaltic samples from Kella area exhibit two compositionally distinct basaltic groups. The Oligocene tholeiitic basalts display low MgO (5.29–6.11 wt.%), TiO2 (2.15–2.47 wt.%), P2O5 (0.28–0.34 wt.%), and high ratio of CaO/Al2O3 (0.68–0.72) and La/Nb (0.89–1.10). Whereas Quaternary and Miocene alkaline basalts display high MgO (7.40–8.86 wt.%), TiO2 (2.4–2.53 wt.%), P2O5 (0.44–0.52 wt.%) and low ratio of CaO/Al2O3 (0.62–0.66) and La/Nb (0.71–0.76). The contrasting incompatible element ratios (e.g., K/Nb, La/Nb, Rb/Zr and Zr/Nb) between tholeiite and alkaline basalts reflect differences in their mantle sources. Major and trace element variations, therefore, reflect the involvement of two geochemically distinct mantle sources in the petrogenesis of Kella basaltic lavas: i) the Oligocene tholeiite basaltic melts derived from enriched asthenosphere mantle source (E-MORB) and ii) the Miocene and Quaternary alkali basaltic melts show a close similarity with ocean island basalts (OIBs) geochemistry, and this end member ascribed to the arrival of Afar plume head. The geochemical modeling reveals that the Oligocene tholeiite basaltic melts produced by an equilibrium melting with 3–5 % degree of partial melting in spinel lherzolite mantle source, whereas the alkali basalts were produced with ∼2% degree of partial melting within spinel-garnet lherzolite transition zone mantle sources.
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Nir N, Knitter D, Hardt J, Schütt B. Human movement and gully erosion: Investigating feedback mechanisms using Frequency Ratio and Least Cost Path analysis in Tigray, Ethiopia. PLoS One 2021; 16:e0245248. [PMID: 33544725 PMCID: PMC7864406 DOI: 10.1371/journal.pone.0245248] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 12/25/2020] [Indexed: 11/26/2022] Open
Abstract
The cost of human movement, whether expressed in time, effort, or distance, is a function of natural and human related variables. At the same time, human movement itself, whether on land, air or sea, causes environmental cost. We are looking into the long-term environmental relationship of this interplay. Gullies-linear landforms, which dissect the landscape-are considered to be a cost for human movement, as they can form unpassable barriers destroying present path networks. On the other hand, human movement creates pathways, which flatten the surface and decrease the water permeability potential. This process results in runoff generation and possibly gully erosion. Accordingly, the spatial relationship between pathways and gullies is investigated. In the Tigray region of the Northern Ethiopian Highlands, gullies and pathways were mapped using remote sensing data. Frequency Ratio was used for assessing pathways as a variable affecting the location of gullies while Least Cost Paths were tested to evaluate the possible constraining impact gullies have on mobility. Based on these results, it is concluded that a positive feedback exists between the cost of human movement and gully erosion. We further discuss possible effects gullies may have had on trade, territory, and political affairs in Tigray. Consequently, we suggest that movement cost and gullying may not only hold strictly environmental or movement-related implications, but also socio-cultural ones.
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Affiliation(s)
- Nadav Nir
- Institute of Geographical Sciences, Freie Universität Berlin, Berlin, Germany
| | - Daniel Knitter
- Department of Geography, Physical Geography, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Jacob Hardt
- Institute of Geographical Sciences, Freie Universität Berlin, Berlin, Germany
| | - Brigitta Schütt
- Institute of Geographical Sciences, Freie Universität Berlin, Berlin, Germany
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Yenehun A, Nigate F, Belay AS, Desta MT, Van Camp M, Walraevens K. Groundwater recharge and water table response to changing conditions for aquifers at different physiography: The case of a semi-humid river catchment, northwestern highlands of Ethiopia. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 748:142243. [PMID: 33113708 DOI: 10.1016/j.scitotenv.2020.142243] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 08/27/2020] [Accepted: 09/04/2020] [Indexed: 06/11/2023]
Abstract
Groundwater recharge estimation, aquifer response to meteorological variables, and evapotranspiration calculations have been performed on a semi-humid catchment, in northwestern Ethiopian plateau. The Soil Moisture Balance (SMB), WetSpass water balance model, Water Table Fluctuation (WTF), and Chloride Mass Balance (CMB) methods are applied to estimate the groundwater recharge. Accordingly, 431 mm, 462 mm, and 477 mm recharge amounts are estimated as mean annual value, respectively, using SMB, WetSpass, and CMB methods. Based on the WTF method, the annual recharge rates of the volcanic aquifers range from 157 mm to 760 mm. The SMB and WetSpass methods are less effective for the flat physiographic area, where the recharge rate is storage controlled rather than precipitation amount. The calculated high recharge for maintain-front aquifers using WTF is attributed to extra rising due to lateral groundwater flow, which restricts the reliability of the method for such aquifer geometries. High groundwater level rising rate (121 mm/day) has been observed for the steeply sloping, low rates (11 mm/day) for the flat floodplain, and intermediate rate (52 mm/day) for the gently sloping volcanic aquifers. Similarly, receding rates of 3.18 mm/day were found for the steeply sloping, 0.40 mm/day for the floodplain, and 1.14 mm/day for the gentle sloping aquifers. The recession, in all of the topographies, is happening with second-order polynomial decay function. A strong connection between the shallow and deep groundwater aquifers is noted. Storage change in the relatively deeper volcanic aquifers is due to vertical groundwater flow from the overlying alluvial aquifer. This indicates that the recharge mechanism is local, and may be the reason for the low aquifer productivity of the Dangila wellfield. Diurnal water table fluctuation is detrended from the receding trend of the dry period, and evapotranspiration from the groundwater is estimated at 28% of total ET.
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Affiliation(s)
- Alemu Yenehun
- School of Earth Sciences, Bahir Dar University, Bahir Dar, Ethiopia; Laboratory for Applied Geology and Hydrogeology, Department of Geology, Ghent University, Gent, Belgium.
| | - Fenta Nigate
- School of Earth Sciences, Bahir Dar University, Bahir Dar, Ethiopia; Laboratory for Applied Geology and Hydrogeology, Department of Geology, Ghent University, Gent, Belgium
| | - Ashebir Sewale Belay
- School of Earth Sciences, Bahir Dar University, Bahir Dar, Ethiopia; Laboratory for Applied Geology and Hydrogeology, Department of Geology, Ghent University, Gent, Belgium
| | | | - Marc Van Camp
- Laboratory for Applied Geology and Hydrogeology, Department of Geology, Ghent University, Gent, Belgium
| | - Kristine Walraevens
- Laboratory for Applied Geology and Hydrogeology, Department of Geology, Ghent University, Gent, Belgium
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6
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Hydrogeology of Volcanic Highlands Affects Prioritization of Land Management Practices. WATER 2020. [DOI: 10.3390/w12102702] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Volcanic highlands supply water to 40% of the world’s population. Soil degradation threatens this water supply. Studies on geohydrology that affect the effectiveness of land and water management (LWM) practices in reducing soil degradations are limited. To aid in the effectiveness of LWM practices, we conducted a field experiment in the Gomit watershed in the semihumid Ethiopian Highlands on the interaction of hydrogeology and LWM practices. We found that in a watershed with strongly faulted tertiary basalt, 30% of the rainfall was drained through faults to another basin. Consequently, the discharge at the outlet was less than half of that of other watersheds with quaternary basalts. Despite the high sediment concentration, i.e., around 15 g L−1, in the Gomit watershed, the sediment yield of less than 4 Mg ha−1 a−1 was below average for the agricultural watershed in Ethiopia because of the low runoff response. While some faults facilitated drainage, others acted as a barrier. Groundwater stored behind the barriers was used as a municipal potable water source. Since the effectiveness of LWM practices depends on the amount of erosion that can be prevented, considerations of country-wide prioritizing of investments in land and water management practices should include the geology of the watersheds.
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7
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Maselli V, Iacopini D, Ebinger CJ, Tewari S, de Haas H, Wade BS, Pearson PN, Francis M, van Vliet A, Richards B, Kroon D. Large-scale mass wasting in the western Indian Ocean constrains onset of East African rifting. Nat Commun 2020; 11:3456. [PMID: 32651391 PMCID: PMC7351987 DOI: 10.1038/s41467-020-17267-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 06/17/2020] [Indexed: 11/09/2022] Open
Abstract
Faulting and earthquakes occur extensively along the flanks of the East African Rift System, including an offshore branch in the western Indian Ocean, resulting in remobilization of sediment in the form of landslides. To date, constraints on the occurrence of submarine landslides at margin scale are lacking, leaving unanswered a link between rifting and slope instability. Here, we show the first overview of landslide deposits in the post-Eocene stratigraphy of the Tanzania margin and we present the discovery of one of the biggest landslides on Earth: the Mafia mega-slide. The emplacement of multiple landslides, including the Mafia mega-slide, during the early-mid Miocene is coeval with cratonic rifting in Tanzania, indicating that plateau uplift and rifting in East Africa triggered large and potentially tsunamigenic landslides likely through earthquake activity and enhanced sediment supply. This study is a first step to evaluate the risk associated with submarine landslides in the region.
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Affiliation(s)
- Vittorio Maselli
- Department of Earth and Environmental Sciences, Life Sciences Centre, Dalhousie University, Halifax, NS, B3H 4R2, Canada.
| | - David Iacopini
- Dipartimento di Scienze della Terra, dell'Ambiente e delle Risorse, Università degli Studi di Napoli Federico II, Naples, 80126, Italy.,School of Geosciences, University of Aberdeen, Aberdeen, AB24 3FX, United Kingdom
| | - Cynthia J Ebinger
- Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA, 70118, United States of America
| | | | - Henk de Haas
- National Marine Facilities, Royal Netherlands Institute for Sea Research and Utrecht University, Utrecht, The Netherlands
| | - Bridget S Wade
- Department of Earth Sciences, University College London, London, WC1E 6BT, United Kingdom
| | - Paul N Pearson
- School of Earth and Ocean Sciences, Cardiff University, Cardiff, CF10 3AT, United Kingdom
| | | | | | - Bill Richards
- Department of Earth and Environmental Sciences, Life Sciences Centre, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Dick Kroon
- School of GeoSciences, University of Edinburgh, Edinburgh, EH9 3FE, United Kingdom
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Muirhead JD, Fischer TP, Oliva SJ, Laizer A, van Wijk J, Currie CA, Lee H, Judd EJ, Kazimoto E, Sano Y, Takahata N, Tiberi C, Foley SF, Dufek J, Reiss MC, Ebinger CJ. Displaced cratonic mantle concentrates deep carbon during continental rifting. Nature 2020; 582:67-72. [PMID: 32494080 DOI: 10.1038/s41586-020-2328-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 03/20/2020] [Indexed: 11/09/2022]
Abstract
Continental rifts are important sources of mantle carbon dioxide (CO2) emission into Earth's atmosphere1-3. Because deep carbon is stored for long periods in the lithospheric mantle4-6, rift CO2 flux depends on lithospheric processes that control melt and volatile transport1,3,7. The influence of compositional and thickness differences between Archaean and Proterozoic lithosphere on deep-carbon fluxes remains untested. Here we propose that displacement of carbon-enriched Tanzanian cratonic mantle concentrates deep carbon below parts of the East African Rift System. Sources and fluxes of CO2 and helium are examined over a 350-kilometre-long transect crossing the boundary between orogenic (Natron and Magadi basins) and cratonic (Balangida and Manyara basins) lithosphere from north to south. Areas of diffuse CO2 degassing exhibit increasing mantle CO2 flux and 3He/4He ratios as the rift transitions from Archaean (cratonic) to Proterozoic (orogenic) lithosphere. Active carbonatite magmatism also occurs near the craton edge. These data indicate that advection of the root of thick Archaean lithosphere laterally to the base of the much thinner adjacent Proterozoic lithosphere creates a zone of highly concentrated deep carbon. This mode of deep-carbon extraction may increase CO2 fluxes in some continental rifts, helping to control the production and location of carbonate-rich magmas.
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Affiliation(s)
- James D Muirhead
- Department of Earth Sciences, Syracuse University, Syracuse, NY, USA. .,School of Environment, University of Auckland, Auckland, New Zealand.
| | - Tobias P Fischer
- Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM, USA.
| | - Sarah J Oliva
- Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA, USA
| | - Amani Laizer
- Department of Geology, University of Dar es Salaam, Dar es Salaam, Tanzania
| | | | - Claire A Currie
- Department of Physics, University of Alberta, Edmonton, Alberta, Canada
| | - Hyunwoo Lee
- School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea
| | - Emily J Judd
- Department of Earth Sciences, Syracuse University, Syracuse, NY, USA
| | - Emmanuel Kazimoto
- Department of Geology, University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Yuji Sano
- Atmosphere and Ocean Research Institute, University of Tokyo, Chiba, Japan
| | - Naoto Takahata
- Atmosphere and Ocean Research Institute, University of Tokyo, Chiba, Japan
| | - Christel Tiberi
- Géosciences Montpellier, CNRS, Université de Montpellier, Montpellier, France
| | - Stephen F Foley
- Department of Earth and Environmental Sciences, Macquarie University, North Ryde, New South Wales, Australia
| | - Josef Dufek
- Department of Earth Sciences, University of Oregon, Eugene, OR, USA
| | - Miriam C Reiss
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Cynthia J Ebinger
- Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA, USA
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Craig EW, Stanley WT, Kerbis Peterhans JC, Bryja J, Meheretu Y. Small terrestrial mammal distributions in Simien Mountains National Park, Ethiopia: a reassessment after 88 years. J Mammal 2020. [DOI: 10.1093/jmammal/gyaa040] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Abstract
Despite the presence of mostly endemic species, the most comprehensive data set on the distribution and ecology of small mammals inhabiting Simien Mountains National Park (SMNP) dated from 1927. The study we carried out and report here provides a unique opportunity to assess the possible role of climate change over the last 88 years on the elevational distribution of mammals in the Ethiopian highlands. Between September and November 2015, three of us (EWC, WTS, YM) collected nonvolant small mammals at four sites (2,900, 3,250, 3,600, and 4,000 m a.s.l.) along the western slope of the Simien Mountains using standardized sampling. Over a 4-week period we recorded 13 species, comprising 11 species of rodents and two of shrews, all endemic to the Ethiopian Plateau. We found the greatest species richness at mid-elevations (3,250 m), consistent with a general pattern found on many other mountains worldwide, but less so in Africa. We compared our species distribution results to the 1927 data set and found upward elevational shifts in species’ ranges, highlighting the role and influence of climate change on the small mammal community. SMNP represents an exceptionally valuable core area of endemism and the best protected natural habitat in northern Ethiopia.
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Affiliation(s)
- Evan W Craig
- Gantz Family Collections Center, Science and Education, Field Museum of Natural History, Chicago, IL, USA
| | - William T Stanley
- Gantz Family Collections Center, Science and Education, Field Museum of Natural History, Chicago, IL, USA
| | - Julian C Kerbis Peterhans
- Gantz Family Collections Center, Science and Education, Field Museum of Natural History, Chicago, IL, USA
- College of Arts & Sciences, Roosevelt University, Chicago, IL, USA
| | - Josef Bryja
- Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, Czech Republic
- Faculty of Science, Department of Botany and Zoology, Masaryk University, Brno, Czech Republic
| | - Yonas Meheretu
- Department of Biology and Institute of Mountain Research & Development, Mekelle University, Mekelle, Ethiopia
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Donovan A, Blundy J, Oppenheimer C, Buisman I. The 2011 eruption of Nabro volcano, Eritrea: perspectives on magmatic processes from melt inclusions. CONTRIBUTIONS TO MINERALOGY AND PETROLOGY. BEITRAGE ZUR MINERALOGIE UND PETROLOGIE 2017; 173:1. [PMID: 31983758 PMCID: PMC6954031 DOI: 10.1007/s00410-017-1425-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 11/14/2017] [Indexed: 06/10/2023]
Abstract
The 2011 eruption of Nabro volcano, Eritrea, produced one of the largest volcanic sulphur inputs to the atmosphere since the 1991 eruption of Mt. Pinatubo, yet has received comparatively little scientific attention. Nabro forms part of an off-axis alignment, broadly perpendicular to the Afar Rift, and has a history of large-magnitude explosive silicic eruptions, as well as smaller more mafic ones. Here, we present and analyse extensive petrological data obtained from samples of trachybasaltic tephra erupted during the 2011 eruption to assess the pre-eruptive magma storage system and explain the large sulphur emission. We show that the eruption involved two texturally distinct batches of magma, one of which was more primitive and richer in sulphur than the other, which was higher in water (up to 2.5 wt%). Modelling of the degassing and crystallisation histories demonstrates that the more primitive magma rose rapidly from depth and experienced degassing crystallisation, while the other experienced isobaric cooling in the crust at around 5 km depth. Interaction between the two batches occurred shortly before the eruption. The eruption itself was likely triggered by recharge-induced destabilisation of vertically extensive mush zone under the volcano. This could potentially account for the large volume of sulphur released. Some of the melt inclusions are volatile undersaturated, and suggest that the original water content of the magma was around 1.3 wt%, which is relatively high for an intraplate setting, but consistent with seismic studies of the Afar plume. This eruption was smaller than some geological eruptions at Nabro, but provides important insights into the plumbing systems and dynamics of off-axis volcanoes in Afar.
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Affiliation(s)
- Amy Donovan
- Department of Geography, King’s College London, London, UK
- Department of Geography, University of Cambridge, Cambridge, UK
| | - Jon Blundy
- School of Earth Sciences, University of Bristol, Bristol, BS8 1RJ UK
| | | | - Iris Buisman
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
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11
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Kappelman J, Tewabe D, Todd L, Feseha M, Kay M, Kocurek G, Nachman B, Tabor N, Yadeta M. Another unique river: a consideration of some of the characteristics of the trunk tributaries of the Nile River in northwestern Ethiopia in relationship to their aquatic food resources. J Hum Evol 2014; 77:117-31. [PMID: 25017504 DOI: 10.1016/j.jhevol.2014.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 03/25/2014] [Accepted: 03/31/2014] [Indexed: 10/25/2022]
Abstract
Aquatic food resources are important components of many modern human hunter-gatherer diets and yet evidence attesting to the widespread exploitation of this food type appears rather late in the archaeological record. While there are times when, for example, the capture of fish and shellfish requires sophisticated technology, there are other cases when the exact ecological attributes of an individual species and the particulars of its environment make it possible for these foods to be incorporated into the human diet with little or no tool use and only a minimal time investment. In order to better understand the full set of variables that are considered in these sorts of foraging decisions, it is necessary to detail the attributes of each particular aquatic environment. We discuss here some of the characteristics of the trunk tributaries of the Nile and Blue Rivers in the Horn of Africa. Unlike typical perennial rivers, these 'temporary' rivers flow only during a brief but intense wet season; during the much longer dry season, the rivers are reduced to a series of increasingly disconnected waterholes, and the abundant and diverse fish and mollusk populations are trapped in ever smaller evaporating pools. The local human population today utilizes a number of diverse capture methods that range from simple to complex, and vary according to the size and depth of the waterhole and the time of the year. When we view the particular characteristics of an individual river system, we find that each river is 'unique' in its individual attributes. The Horn of Africa is believed to be along the route that modern humans followed on their migration out of Africa, and it is likely that the riverine-based foraging behaviors of these populations accompanied our species on its movement into the rest of the Old World.
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Affiliation(s)
- John Kappelman
- Department of Anthropology, University of Texas at Austin, Austin, TX, USA.
| | - Dereje Tewabe
- Bahir Dar Fishery and Aquatic Life Research Center, Bahir Dar, Ethiopia.
| | - Lawrence Todd
- Department of Anthropology, University of Texas at Austin, Austin, TX, USA.
| | - Mulugeta Feseha
- Paleoanthropology and Paleoenvironment Program, School of Earth Science, Addis Ababa University, Addis Ababa, Ethiopia.
| | - Marvin Kay
- Department of Anthropology, University of Arkansas, Fayetteville, AR, USA.
| | - Gary Kocurek
- Department of Geological Sciences, Jackson School, University of Texas at Austin, Austin, TX, USA.
| | - Brett Nachman
- Department of Anthropology, University of Texas at Austin, Austin, TX, USA.
| | - Neil Tabor
- Roy M. Huffington Department of Earth Sciences, Southern Methodist University, Dallas, TX, USA.
| | - Meklit Yadeta
- Paleoanthropology and Paleoenvironment Program, School of Earth Science, Addis Ababa University, Addis Ababa, Ethiopia.
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12
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Ferguson DJ, Maclennan J, Bastow ID, Pyle DM, Jones SM, Keir D, Blundy JD, Plank T, Yirgu G. Melting during late-stage rifting in Afar is hot and deep. Nature 2013; 499:70-3. [PMID: 23823795 DOI: 10.1038/nature12292] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Accepted: 05/01/2013] [Indexed: 11/09/2022]
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13
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Fournier M, Chamot-Rooke N, Petit C, Huchon P, Al-Kathiri A, Audin L, Beslier MO, d'Acremont E, Fabbri O, Fleury JM, Khanbari K, Lepvrier C, Leroy S, Maillot B, Merkouriev S. Arabia-Somalia plate kinematics, evolution of the Aden-Owen-Carlsberg triple junction, and opening of the Gulf of Aden. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2008jb006257] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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14
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Chenet AL, Fluteau F, Courtillot V, Gérard M, Subbarao KV. Determination of rapid Deccan eruptions across the Cretaceous-Tertiary boundary using paleomagnetic secular variation: Results from a 1200-m-thick section in the Mahabaleshwar escarpment. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2006jb004635] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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15
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Bird P, Ben-Avraham Z, Schubert G, Andreoli M, Viola G. Patterns of stress and strain rate in southern Africa. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jb003882] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Yirgu G, Ebinger C, Maguire P. The Afar volcanic province within the East African Rift System: introduction. ACTA ACUST UNITED AC 2006. [DOI: 10.1144/gsl.sp.2006.259.01.01] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- G. Yirgu
- Department of Geology and Geophysics, University of Addis Ababa
PO Box 176, Addis Abada, Ethiopia
| | - C.J. Ebinger
- Department of Geology, Royal Holloway, University of London
Egham, TW20 0EX, UK
| | - P.K.H. Maguire
- Department of Geology, University of Leicester
Leicester LE1 7RH, UK
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17
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Beresford P, Barker FK, Ryan PG, Crowe TM. African endemics span the tree of songbirds (Passeri): molecular systematics of several evolutionary 'enigmas'. Proc Biol Sci 2005; 272:849-58. [PMID: 15888418 PMCID: PMC1599865 DOI: 10.1098/rspb.2004.2997] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2004] [Accepted: 10/25/2004] [Indexed: 11/12/2022] Open
Abstract
The deep divergence between the African endemic passerines Picathartidae (rockfowl Picathartes and rockjumpers Chaetops, four species) and the Passerida (ca. 3500 species) suggests an older history of oscines on the African continent than has previously been assumed. In order to determine whether any additional, unexpectedly deep lineages occur in African endemic songbirds, 29 species--including 10 enigmatic focal taxa endemic to southern Africa--were added to a large nuclear sequence dataset gathered from oscine songbirds (Passeri). Phylogenetic analyses of these data resolve many long-standing questions about the affinities of these birds, not all of which were predicted by traditional approaches. The application of a molecular clock indicates that most basal divergences in Passerida occurred in the middle to late Eocene, with divergences between African and Australasian core corvoids occurring somewhat later in the early Miocene. Consistent with inferences for mammals, divergences between Malagasy endemic passerines and their mainland relatives suggests an asynchronous colonization history. This emerging phylogenetic picture reveals that relationships within Old World families are highly informative regarding the early dispersal and radiation of songbirds out of Gondwana. Future analyses will depend on improving resolution of higher-level phylogenetic relationships among these groups, and increasing the density of taxon sampling within them.
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Affiliation(s)
- P Beresford
- Percy FitzPatrick Institute, University of Cape Town, Private Bag, Rondebosch 7701, South Africa.
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18
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Lahitte P, Gillot PY, Kidane T, Courtillot V, Bekele A. New age constraints on the timing of volcanism in central Afar, in the presence of propagating rifts. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2001jb001689] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Pierre Lahitte
- Laboratoire de Géochronologie Multi-Techniques UPS-IPGP; Université Paris-Sud; Orsay France
| | - Pierre-Yves Gillot
- Laboratoire de Géochronologie Multi-Techniques UPS-IPGP; Université Paris-Sud; Orsay France
| | - Tesfaye Kidane
- Laboratoires de Paléomagnétisme et de Tectonique; Institut de Physique du Globe de Paris; Paris France
| | - Vincent Courtillot
- Laboratoires de Paléomagnétisme et de Tectonique; Institut de Physique du Globe de Paris; Paris France
| | - Abebe Bekele
- Department of Geology and Geophysics; University of Addis-Ababa; Addis-Ababa Ethiopia
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19
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Kidane T, Courtillot V, Manighetti I, Audin L, Lahitte P, Quidelleur X, Gillot PY, Gallet Y, Carlut J, Haile T. New paleomagnetic and geochronologic results from Ethiopian Afar: Block rotations linked to rift overlap and propagation and determination of a ∼2 Ma reference pole for stable Africa. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2001jb000645] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tesfaye Kidane
- Laboratoires de Paléomagnétisme et de Tectonique; Institut de Physique du Globe de Paris; Paris France
- Department of Geology and Geophysics; University of Addis-Ababa; Addis-Ababa Ethiopia
| | - Vincent Courtillot
- Laboratoires de Paléomagnétisme et de Tectonique; Institut de Physique du Globe de Paris; Paris France
| | - Isabelle Manighetti
- Laboratoires de Paléomagnétisme et de Tectonique; Institut de Physique du Globe de Paris; Paris France
| | - Laurence Audin
- Laboratoires de Paléomagnétisme et de Tectonique; Institut de Physique du Globe de Paris; Paris France
- Institut de Recherche pour le Devoloppement; Université Paul Sabatier, Géologie; Toulouse France
| | - Pierre Lahitte
- Laboratoire de Géochronologie Multi-Techniques, Université Paris Sud-Institut de Physique du Globe de Paris, Sciences de la Terre; Université Paris XI-Paris Sud; Orsay France
| | - Xavier Quidelleur
- Laboratoires de Paléomagnétisme et de Tectonique; Institut de Physique du Globe de Paris; Paris France
- Laboratoire de Géochronologie Multi-Techniques, Université Paris Sud-Institut de Physique du Globe de Paris, Sciences de la Terre; Université Paris XI-Paris Sud; Orsay France
| | - Pierre-Yves Gillot
- Laboratoire de Géochronologie Multi-Techniques, Université Paris Sud-Institut de Physique du Globe de Paris, Sciences de la Terre; Université Paris XI-Paris Sud; Orsay France
| | - Yves Gallet
- Laboratoires de Paléomagnétisme et de Tectonique; Institut de Physique du Globe de Paris; Paris France
| | - Julie Carlut
- Laboratoire de Géologie; Ecole Normale Supérieure; Paris France
| | - Tigistu Haile
- Department of Geology and Geophysics; University of Addis-Ababa; Addis-Ababa Ethiopia
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20
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Kirschvink JL, Gaidos EJ, Bertani LE, Beukes NJ, Gutzmer J, Maepa LN, Steinberger RE. Paleoproterozoic snowball earth: extreme climatic and geochemical global change and its biological consequences. Proc Natl Acad Sci U S A 2000; 97:1400-5. [PMID: 10677473 PMCID: PMC26445 DOI: 10.1073/pnas.97.4.1400] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/1999] [Accepted: 11/08/1999] [Indexed: 11/18/2022] Open
Abstract
Geological, geophysical, and geochemical data support a theory that Earth experienced several intervals of intense, global glaciation ("snowball Earth" conditions) during Precambrian time. This snowball model predicts that postglacial, greenhouse-induced warming would lead to the deposition of banded iron formations and cap carbonates. Although global glaciation would have drastically curtailed biological productivity, melting of the oceanic ice would also have induced a cyanobacterial bloom, leading to an oxygen spike in the euphotic zone and to the oxidative precipitation of iron and manganese. A Paleoproterozoic snowball Earth at 2.4 Giga-annum before present (Ga) immediately precedes the Kalahari Manganese Field in southern Africa, suggesting that this rapid and massive change in global climate was responsible for its deposition. As large quantities of O(2) are needed to precipitate this Mn, photosystem II and oxygen radical protection mechanisms must have evolved before 2.4 Ga. This geochemical event may have triggered a compensatory evolutionary branching in the Fe/Mn superoxide dismutase enzyme, providing a Paleoproterozoic calibration point for studies of molecular evolution.
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Affiliation(s)
- J L Kirschvink
- Division of Geological Sciences, Jet Propulsion Laboratory, and Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
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Ritsema J, Woodhouse JH. Complex Shear Wave Velocity Structure Imaged Beneath Africa and Iceland. Science 1999; 286:1925-1928. [PMID: 10583949 DOI: 10.1126/science.286.5446.1925] [Citation(s) in RCA: 684] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A model of three-dimensional shear wave velocity variations in the mantle reveals a tilted low velocity anomaly extending from the core-mantle boundary (CMB) region beneath the southeastern Atlantic Ocean into the upper mantle beneath eastern Africa. This anomaly suggests that Cenozoic flood basalt volcanism in the Afar region and active rifting beneath the East African Rift is linked to an extensive thermal anomaly at the CMB more than 45 degrees away. In contrast, a low velocity anomaly beneath Iceland is confined to the upper mantle.
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Affiliation(s)
- J Ritsema
- Seismological Laboratory, California Institute of Technology, Pasadena, CA 91125, USA. Department of Earth Sciences, Oxford University, Oxford OX1 3PR, UK
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22
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Fluteau F, Ramstein G, Besse J. Simulating the evolution of the Asian and African monsoons during the past 30 Myr using an atmospheric general circulation model. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999jd900048] [Citation(s) in RCA: 141] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Cashman K, Pinkerton H, Stephenson J. Introduction to Special Section: Long Lava Flows. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/98jb01820] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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