The upper mantle beneath Patagonia,Argentina, documented by xenoliths from alkali basalts |
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| Institution: | 1. GEOPOLAR, Institute of Geography, University of Bremen, Celsiusstr. FVG-M, D-28359 Bremen, Germany;2. CONICET, CENAC/APN, Fagnano 244, 8400 Bariloche, Argentina;3. Physical Geography, Institute of Geography, University of Jena, Löbdergraben 32, D-07743 Jena, Germany;4. Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina;5. Institute of Bio- and Geosciences, IBG-3: Agrosphere, Research Center Jülich, D-52425 Jülich, Germany;6. Institute of Geography, University of Erlangen-Nürnberg, Kochstr. 4/4, D-91054 Erlangen, Germany;7. Department of Earth and Environmental Sciences, University of Munich, Richard-Wagner-Str. 10, D-80333 Munich, Germany;8. GeoBio-Center, University of Munich, Richard-Wagner-Str. 10, D-80333 Munich, Germany;9. Seminar für Geographie und ihre Didaktik, University of Cologne, Gronewaldstr. 2, D-50931 Cologne, Germany;10. Argentine Museum of Natural History, Av. Angel Gallardo 470, Buenos Aires, Argentina;11. Canada Research Chair in Marine Geology, Institut des sciences de la mer de Rimouski (ISMER), UQAR, Rimouski, Québec G5L 3A1, Canada;1. Department of Geological Engineering, Karadeniz Technical University, 61080 Trabzon, Turkey;2. Department of Geological Engineering, Dokuz Eylül University, 35160 Izmir, Turkey;3. Department of Geology & Environmental Earth Science, Miami University, Oxford, OH 45056, USA;4. School of Earth Science and Geological Engineering, Sun Yat-sen University, Guangzhou, PR China;5. General Directorate of MTA, Geological Research Department, 06520 Ankara, Turkey;1. Departamento de Mineralogía y Petrología, Facultad de Ciencias, Universidad de Granada, Avenida Fuentenueva s/n, 18002 Granada, Spain;2. Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Avenida de las Palmeras 4, 18100 Armilla, Granada, Spain;3. Departament de Cristal·Lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, Barcelona, Spain;4. Department of Earth and Environmental Sciences, The George Washington University, Washington DC, USA |
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| Abstract: | Mantle xenoliths in alkali basaltic lavas (with ocean-island basalt chemical signatures) and cinder cones occur in several areas of Patagonia. A representative suite of mantle xenoliths was collected in the region between latitudes 40° and 52°S and longitudes 67° and 71°W in the Río Negro, Chubut, and Santa Cruz provinces, Argentina. Mantle xenoliths in Patagonia display distinguishing peculiarities compared with those of other worldwide occurrences. The lithospheric mantle beneath Patagonia, as inferred from chemical variation diagrams, has experienced only minor melt extractions in the garnet peridotite field and more extensive melt extractions in the spinel lherzolite field. Variably intensive cryptic and modal metasomatism affected the lithospheric mantle in this region. Textural evidence shows that the mantle is moderately to strongly tectonized and recrystallized on both the local and the regional scale, with an overall predominance of deformed textural types. Mineral equilibrium indicates a strongly elevated geotherm similar to the southeast Australia and oceanic geotherms, which is not normal for a continental intraplate tectonic setting. Therefore, the properties of the Patagonian samples are probably related to the presence of rising mantle plume(s) in an extensional tectonic setting. |
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