Ordovician K-bentonites in the Argentine Precordillera: relations to Gondwana margin evolution
Ordovician K-bcn Ionites have now been recorded from >20 localities in the vicinity of the Argentine Prccordillera. Most occur in I he eastern thrust belts, in the San Juan Limestone and the overlying the Gualcamayo Formation, but a few ash beds are known also from the central thrust belts. T...
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| Formato: | Libro Capitulo de libro |
| Lenguaje: | Español |
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The Geological Society
1998
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| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/158353 |
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I19-R120-10915-1583532023-10-04T04:07:01Z http://sedici.unlp.edu.ar/handle/10915/158353 Ordovician K-bentonites in the Argentine Precordillera: relations to Gondwana margin evolution Huff, Warren D. Bergström, Stig M. Kolata, Dennis R. Cingolani, Carlos Alberto Astini, Ricardo A. 1998 2023-10-03T18:55:04Z Pankhurst, Robert J. Rapela, Carlos Washington The Geological Society es Geología Ordovician K-bcn Ionites have now been recorded from >20 localities in the vicinity of the Argentine Prccordillera. Most occur in I he eastern thrust belts, in the San Juan Limestone and the overlying the Gualcamayo Formation, but a few ash beds are known also from the central thrust belts. The oldest occur in the middle Arenig t. victorias iunatus grnplolite (Oe. evae conodont) Zone, and the youngest in the middle Llanvirn P. etegans (P. .tuecicas) Zone. Mineralogical characteristics, typical of other Ordovician K-bentonites, include a matrix of illite/smectite mixed-layer clay and a typical felsic volcanic phenocryst assemblage: biotite, beta-form quartz, alkali and plagioclase feldspar, apatite, and zircon, with lesser amounts of hornblende, clinopyroxene, tilanilc and Fe-Ti oxides. The proportions of the mineral phases and variations iii their crystal chemistry are commonly unique to individual (or small groups of) K-benlonite beds. Glass melt inclusions preserved in quartz are rhyolitic in composition The sequence is unique in its abundance of K-benlonite beds, but a close association between the Precordillera and other Ordovician sedimentary basins cannot be established.Theash distribution is most consistent with palacogeographical reconstructions in which early Ordovician drifting of the Precordillera occurred in proximity to one or more volcanic arcs, and with eventual collision along the Andean margin of Gondwana during the mid-Ordovician Ocloyic event of the Famalinian orogeny. The Puna-Famatina terrane northeast of the Precordillera might have served as the source of the K-bcnlonite ashes, possibly in concert with active arc magmatism on the Gondwana plate itself. Centro de Investigaciones Geológicas Libro Capitulo de libro http://creativecommons.org/licenses/by-nc-sa/4.0/ Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) application/pdf 107-126 |
| institution |
Universidad Nacional de La Plata |
| institution_str |
I-19 |
| repository_str |
R-120 |
| collection |
SEDICI (UNLP) |
| language |
Español |
| topic |
Geología |
| spellingShingle |
Geología Huff, Warren D. Bergström, Stig M. Kolata, Dennis R. Cingolani, Carlos Alberto Astini, Ricardo A. Pankhurst, Robert J. Rapela, Carlos Washington Ordovician K-bentonites in the Argentine Precordillera: relations to Gondwana margin evolution |
| topic_facet |
Geología |
| description |
Ordovician K-bcn Ionites have now been recorded from >20 localities in the vicinity of the Argentine Prccordillera. Most occur in I he eastern thrust belts, in the San Juan Limestone and the overlying the Gualcamayo Formation, but a few ash beds are known also from the central thrust belts. The oldest occur in the middle Arenig t. victorias iunatus grnplolite (Oe. evae conodont) Zone, and the youngest in the middle Llanvirn P. etegans (P. .tuecicas) Zone. Mineralogical characteristics, typical of other Ordovician K-bentonites, include a matrix of illite/smectite mixed-layer clay and a typical felsic volcanic phenocryst assemblage: biotite, beta-form quartz, alkali and plagioclase feldspar, apatite, and zircon, with lesser amounts of hornblende, clinopyroxene, tilanilc and Fe-Ti oxides. The proportions of the mineral phases and variations iii their crystal chemistry are commonly unique to individual (or small groups of) K-benlonite beds. Glass melt inclusions preserved in quartz are rhyolitic in composition The sequence is unique in its abundance of K-benlonite beds, but a close association between the Precordillera and other Ordovician sedimentary basins cannot be established.Theash distribution is most consistent with palacogeographical reconstructions in which early Ordovician drifting of the Precordillera occurred in proximity to one or more volcanic arcs, and with eventual collision along the Andean margin of Gondwana during the mid-Ordovician Ocloyic event of the Famalinian orogeny. The Puna-Famatina terrane northeast of the Precordillera might have served as the source of the K-bcnlonite ashes, possibly in concert with active arc magmatism on the Gondwana plate itself. |
| format |
Libro Capitulo de libro |
| author |
Huff, Warren D. Bergström, Stig M. Kolata, Dennis R. Cingolani, Carlos Alberto Astini, Ricardo A. Pankhurst, Robert J. Rapela, Carlos Washington |
| author_facet |
Huff, Warren D. Bergström, Stig M. Kolata, Dennis R. Cingolani, Carlos Alberto Astini, Ricardo A. Pankhurst, Robert J. Rapela, Carlos Washington |
| author_sort |
Huff, Warren D. |
| title |
Ordovician K-bentonites in the Argentine Precordillera: relations to Gondwana margin evolution |
| title_short |
Ordovician K-bentonites in the Argentine Precordillera: relations to Gondwana margin evolution |
| title_full |
Ordovician K-bentonites in the Argentine Precordillera: relations to Gondwana margin evolution |
| title_fullStr |
Ordovician K-bentonites in the Argentine Precordillera: relations to Gondwana margin evolution |
| title_full_unstemmed |
Ordovician K-bentonites in the Argentine Precordillera: relations to Gondwana margin evolution |
| title_sort |
ordovician k-bentonites in the argentine precordillera: relations to gondwana margin evolution |
| publisher |
The Geological Society |
| publishDate |
1998 |
| url |
http://sedici.unlp.edu.ar/handle/10915/158353 |
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