Geochemical and Sr-Nd isotopic characterization of the Miocene volcanic events in the Sierra Madre del Sur, central and southeastern Oaxaca, Mexico
Fuente:
Redalyc
Gespeichert in:
| 1. Verfasser: | |
|---|---|
| Format: | Artículo científico |
| Sprache: | en |
| Veröffentlicht: |
Universidad Nacional Autónoma de México
2008
|
| Schlagworte: | |
| Online-Zugang: | |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| _version_ | 1876456071047938048 |
|---|---|
| author | Raymundo G. Martínez Serrano |
| author_facet | Raymundo G. Martínez Serrano |
| contents | Geochemical and Sr-Nd isotopic characterization of the Miocene volcanic events in the Sierra Madre del Sur, central and southeastern Oaxaca, Mexico Raymundo G. Martínez Serrano Gabriela Solís Pichardo E. Leticia Flores Márquez Consuelo Macías Romo Jaime Delgado Durán Ciencias de la Tierra Sr Mexico Miocene Geochemistry volcanic rocks The Etla, Mitla-Tlacolula and Nejapa volcanic regions in central and southeastern Oaxacacomprise the southeastern part of a wide Cenozoic magmatic arc in the Sierra Madre del Sur. Mostvolcanic events in these regions ocurred between 22 to 15 Ma, almost contemporaneously with theinitial volcanic events of the Trans-Mexican Volcanic Belt. Petrographic, geochemical, and isotopiccharacteristics were determined for representative volcanic samples from the three regions, whereignimbrites, volcaniclastic and epiclastic deposits, lava flows and minor lacustrine deposits are found.In a SiO2 vs. alkalis diagram, chemical classification of volcanic products for the study area indicatevariations from basaltic andesites to rhyolites, following a subalkaline trend, but with a bimodal pattern.Components with SiO2 concentrations between 58 to 67 wt. % are absent. The trace-element patterns forandesites and rhyolites are similar, with enrichment in the large-ion lithophile elements relative to the high-field-strength elements. Chondrite-normalized REE patterns display light rare earth element enrichment(La-Sm) with respect to the heavy rare earth elements (Eu-Lu), which show flat patterns. These chemicalcharacteristics are typical of volcanic arc rocks. Initial Sr and Nd isotopic data show certain differencesbetween samples from the Etla and Mitla-Tlacolula regions (87Sr/86Sr: 0.7047 to 0.7066 and εNd: -1.15to 1.75) and the Nejapa region (87Sr/86Sr: 0.7035 to 0.7048 and εNd: +0.52 to +1.42). These data andthose reported for the basement rocks suggest greater involvement of continental crust for the magmasof the two first regions in comparison to magmas of the Nejapa region. The isotopic compositions aresimilar to those observed in other volcanic regions of the Sierra Madre del Sur. Early to middle Miocenevolcanic events in central and southeastern Oaxaca, together with the contemporaneous initial magmaticevents in the Trans-Mexican Volcanic Belt, could conform a magmatic arc with an anomalous orientationbefore attaining its present position 2008 artículo científico 1026-8774 https://www.redalyc.org/articulo.oa?id=57225101 en http://www.redalyc.org/revista.oa?id=572 Revista Mexicana de Ciencias Geológicas application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Ciencias Geológicas (México) Num.1 Vol.25 |
| format | Artículo científico |
| id | redalyc_57225101 |
| institution | Redalyc |
| language | en |
| publishDate | 2008 |
| publisher | Universidad Nacional Autónoma de México |
| spellingShingle | Geochemical and Sr-Nd isotopic characterization of the Miocene volcanic events in the Sierra Madre del Sur, central and southeastern Oaxaca, Mexico Raymundo G. Martínez Serrano Ciencias de la Tierra Sr Mexico Miocene Geochemistry volcanic rocks Geochemical and Sr-Nd isotopic characterization of the Miocene volcanic events in the Sierra Madre del Sur, central and southeastern Oaxaca, Mexico Raymundo G. Martínez Serrano Gabriela Solís Pichardo E. Leticia Flores Márquez Consuelo Macías Romo Jaime Delgado Durán Ciencias de la Tierra Sr Mexico Miocene Geochemistry volcanic rocks The Etla, Mitla-Tlacolula and Nejapa volcanic regions in central and southeastern Oaxacacomprise the southeastern part of a wide Cenozoic magmatic arc in the Sierra Madre del Sur. Mostvolcanic events in these regions ocurred between 22 to 15 Ma, almost contemporaneously with theinitial volcanic events of the Trans-Mexican Volcanic Belt. Petrographic, geochemical, and isotopiccharacteristics were determined for representative volcanic samples from the three regions, whereignimbrites, volcaniclastic and epiclastic deposits, lava flows and minor lacustrine deposits are found.In a SiO2 vs. alkalis diagram, chemical classification of volcanic products for the study area indicatevariations from basaltic andesites to rhyolites, following a subalkaline trend, but with a bimodal pattern.Components with SiO2 concentrations between 58 to 67 wt. % are absent. The trace-element patterns forandesites and rhyolites are similar, with enrichment in the large-ion lithophile elements relative to the high-field-strength elements. Chondrite-normalized REE patterns display light rare earth element enrichment(La-Sm) with respect to the heavy rare earth elements (Eu-Lu), which show flat patterns. These chemicalcharacteristics are typical of volcanic arc rocks. Initial Sr and Nd isotopic data show certain differencesbetween samples from the Etla and Mitla-Tlacolula regions (87Sr/86Sr: 0.7047 to 0.7066 and εNd: -1.15to 1.75) and the Nejapa region (87Sr/86Sr: 0.7035 to 0.7048 and εNd: +0.52 to +1.42). These data andthose reported for the basement rocks suggest greater involvement of continental crust for the magmasof the two first regions in comparison to magmas of the Nejapa region. The isotopic compositions aresimilar to those observed in other volcanic regions of the Sierra Madre del Sur. Early to middle Miocenevolcanic events in central and southeastern Oaxaca, together with the contemporaneous initial magmaticevents in the Trans-Mexican Volcanic Belt, could conform a magmatic arc with an anomalous orientationbefore attaining its present position 2008 artículo científico 1026-8774 https://www.redalyc.org/articulo.oa?id=57225101 en http://www.redalyc.org/revista.oa?id=572 Revista Mexicana de Ciencias Geológicas application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Ciencias Geológicas (México) Num.1 Vol.25 |
| title | Geochemical and Sr-Nd isotopic characterization of the Miocene volcanic events in the Sierra Madre del Sur, central and southeastern Oaxaca, Mexico |
| topic | Ciencias de la Tierra Sr Mexico Miocene Geochemistry volcanic rocks |
| url | https://www.redalyc.org/articulo.oa?id=57225101 |