Geology and geochronology of the Tana Basin, Ethiopia : LIP volcanism, super eruptions and Eocene-Oligocene environmental change
| Autor: | Harry Toland, Anthony R. Prave, Daniel J. Condon, Colin H. Donaldson, Darren F. Mark, Timothy D. Raub, C. R. Bates |
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| Přispěvatelé: | University of St Andrews. School of Earth & Environmental Sciences, University of St Andrews. Marine Alliance for Science & Technology Scotland, University of St Andrews. Scottish Oceans Institute, University of St Andrews. St Andrews Sustainability Institute, University of St Andrews. St Andrews Isotope Geochemistry, University of St Andrews. Earth and Environmental Sciences, University of St Andrews. Centre for Ancient Environmental Studies |
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
010504 meteorology & atmospheric sciences
Large igneous province Geochemistry NDAS Silicic Flood basalt 010502 geochemistry & geophysics 01 natural sciences Eocene-Oligocene transition Paleontology Geochemistry and Petrology G1 Earth and Planetary Sciences (miscellaneous) 0105 earth and related environmental sciences Basalt Felsic G Geography (General) LIP Geophysics Space and Planetary Science Geochronology Earth Sciences Mafic Super eruption BDC Lake Tana Geology Zircon |
| Popis: | This work was supported by NERC Grants NE/D012996/1 and NER/B/S/2002/00540 and NIGFSC IP/1024/0508. New geological and geochronological data define four episodes of volcanism for the Lake Tana region in the northern Ethiopian portion of the Afro–Arabian Large Igneous Province (LIP): pre-31 Ma flood basalt that yielded a single 40Ar/39Ar age of 34.05 ± 0.54/0.56 Ma; thick and extensive felsic ignimbrites and rhyolites (minimum volume of 2-3 x 103km3) erupted between 31.108 ± 0.020/0.041 Ma and 30.844 ± 0.027/0.046 Ma (U–Pb CA-ID-TIMS zircon ages); mafic volcanism bracketed by 40Ar/39Ar ages of 28.90 ± 0.12/0.14 Ma and 23.75 ± 0.02/0.04 Ma; and localised scoraceous basalt with an 40Ar/39Ar age of 0.033 ± 0.005/0.005 Ma. The felsic volcanism was the product of super eruptions that created a 60–80 km diameter caldera marked by km-scale caldera-collapse fault blocks and a steep-sided basin filled with a minimum of 180 m of sediment and the present-day Lake Tana. These new data enable mapping, with a finer resolution than previously possible, Afro–Arabian LIP volcanism onto the timeline of the Eocene–Oligocene transition and show that neither the mafic nor silicic volcanism coincides directly with perturbations in the geochemical records that span that transition. Our results reinforce the view that it is not the development of a LIP alone but its rate of effusion that contributes to inducing global-scale environmental change. Postprint |
| Databáze: | OpenAIRE |
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