Slab window-related magmatism from southernmost South America: the Late Miocene mafic volcanics from the Estancia Glencross Area (ca. 52°S, Argentina?Chile)
| Autor: | D'Orazio M. 1), Agostini S. 3), Innocenti F. 1), Haller M.J. 2), Manetti P. 3), Mazzarini F. 3) |
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| Rok vydání: | 2001 |
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| Zdroj: | Lithos (Oslo. Print) 57 (2001): 67–89. info:cnr-pdr/source/autori:D'Orazio M. 1), Agostini S. 3), Innocenti F. 1), Haller M.J. 2), Manetti P. 3), Mazzarini F. 3)/titolo:Slab window-related magmatism from southernmost South America: the Late Miocene mafic volcanics from the Estancia Glencross Area (ca. 52°S, Argentina?Chile)/doi:/rivista:Lithos (Oslo. Print)/anno:2001/pagina_da:67/pagina_a:89/intervallo_pagine:67–89/volume:57 |
| Popis: | The Estancia Glencross Area EGA volcanic rocks form a series of five isolated buttes located at the southern end ca. 52°S of the discontinuous belt of Cenozoic basaltic lava formations occurring in the extra-Andean Patagonia. EGA volcanics are subalkaline basalts and basaltic andesites erupted at 8.0-8.5 Ma in a region closely behind the Andean Cordillera. EGA volcanism predated by about 4-5 My the onset of the volcanism in the nearby Pali Aike Volcanic Field, which produced highly primitive, alkaline lavas. Incompatible trace-element distributions and Sr-Nd isotope compositions of EGA rocks are those typical of within-plate OIB-type basalts and are indicative of minimal interaction of sub-lithospheric magmas with enriched reservoirs. The geochemical characteristics of EGA volcanics, as well as their age and location are consistent with a model of slab window opening beneath this region. The high silica content and the garnet signature of the estimated EGA primary magma are explained by a two-stage process involving the initial production of melts from a garnet lherzolite source followed by the reaction of these melts with harzburgite country rocks during their ascent through the mantle lithosphere. The melt/harzburgite reaction, favoured by a slow melt ascent rate, as well as the low magma production at EGA, are likely related to the dominantly compressive stress regime operating in this area during Late Miocene. |
| Databáze: | OpenAIRE |
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