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| Format: | Artículo científico |
| Language: | en |
| Published: |
Universitat de Barcelona
2006
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| Online Access: | https://www.redalyc.org/articulo.oa?id=50540211 |
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| _version_ | 1866812485887066112 |
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| author | E. Gazel |
| author_facet | E. Gazel |
| contents | Magmatic and geotectonic significance of Santa Elena Peninsula, Costa Rica E. Gazel P. Denyer P.O. Baumgartner Ciencias de la Tierra Geochemistry Ultramafic Complex Oceanic assemblages Accretionary complex Santa Elena Peninsula We present a new integrated interpretation of the geochemistry and geotectonic significance of the Santa ElenaPeninsula, which is divided in three units: 1) an overthrust allocthonous unit of ultramafic and mafic rocks, theSanta Elena Nappe; 2) an autochthonous basaltic sedimentary suite, resting immediately below the overthrust,the Santa Rosa Accretionary Complex; and 3) Islas Murciélago pillow and massive basaltic flows. In the SantaElena Nappe three petrological affinities have been recognized: 1) the ultramafic complex, that corresponds todepleted (MORB-like) mantle serpentinizated peridotites, with very low TiO2 and high Ni and Cr; 2) the pegmatiticgabbros, layered gabbros and plagiogranites and basaltic dikes with low TiO2 (< 0.89%) contents andhigh LREE depletions; and 3) the doleritic dykes with higher TiO2 (>0.89%). These mafic associations havegeochemical signatures that suggest an island arc origin and petrographic evidences of low grade metamorphismand hydrothermal alteration. The Santa Rosa Accretionary Complex includes pelagic and volcanoclasticsediments, tuffs and alkaline magmatic rocks, originated by low degree melting of enrichment OIB mantlesource, and probably related with seamount portions incorporated into the accretionary prism. Islas Murciélagopillow and massive basalts show no clear structural relationship with the rest of the units, but are geochemicallysimilar to the dolerites of the Santa Elena Nappe. Sr, Nd, and Pb isotopic ratios of the Santa Elena Nappe andthe Santa Elena Accretionary Complex samples do not correspond to the Galapagos Mantle array, and have differentmantle reservoirs and geochemical characteristics than the Nicoya Complex. 2006 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50540211 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Num.1-2 Vol.4 |
| format | Artículo científico |
| id | redalyc_50540211 |
| language | en |
| publishDate | 2006 |
| publisher | Universitat de Barcelona |
| spellingShingle | Magmatic and geotectonic significance of Santa Elena Peninsula, Costa Rica E. Gazel Ciencias de la Tierra Geochemistry Ultramafic Complex Oceanic assemblages Accretionary complex Santa Elena Peninsula Magmatic and geotectonic significance of Santa Elena Peninsula, Costa Rica E. Gazel P. Denyer P.O. Baumgartner Ciencias de la Tierra Geochemistry Ultramafic Complex Oceanic assemblages Accretionary complex Santa Elena Peninsula We present a new integrated interpretation of the geochemistry and geotectonic significance of the Santa ElenaPeninsula, which is divided in three units: 1) an overthrust allocthonous unit of ultramafic and mafic rocks, theSanta Elena Nappe; 2) an autochthonous basaltic sedimentary suite, resting immediately below the overthrust,the Santa Rosa Accretionary Complex; and 3) Islas Murciélago pillow and massive basaltic flows. In the SantaElena Nappe three petrological affinities have been recognized: 1) the ultramafic complex, that corresponds todepleted (MORB-like) mantle serpentinizated peridotites, with very low TiO2 and high Ni and Cr; 2) the pegmatiticgabbros, layered gabbros and plagiogranites and basaltic dikes with low TiO2 (< 0.89%) contents andhigh LREE depletions; and 3) the doleritic dykes with higher TiO2 (>0.89%). These mafic associations havegeochemical signatures that suggest an island arc origin and petrographic evidences of low grade metamorphismand hydrothermal alteration. The Santa Rosa Accretionary Complex includes pelagic and volcanoclasticsediments, tuffs and alkaline magmatic rocks, originated by low degree melting of enrichment OIB mantlesource, and probably related with seamount portions incorporated into the accretionary prism. Islas Murciélagopillow and massive basalts show no clear structural relationship with the rest of the units, but are geochemicallysimilar to the dolerites of the Santa Elena Nappe. Sr, Nd, and Pb isotopic ratios of the Santa Elena Nappe andthe Santa Elena Accretionary Complex samples do not correspond to the Galapagos Mantle array, and have differentmantle reservoirs and geochemical characteristics than the Nicoya Complex. 2006 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50540211 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Num.1-2 Vol.4 |
| title | Magmatic and geotectonic significance of Santa Elena Peninsula, Costa Rica |
| topic | Ciencias de la Tierra Geochemistry Ultramafic Complex Oceanic assemblages Accretionary complex Santa Elena Peninsula |
| url | https://www.redalyc.org/articulo.oa?id=50540211 |