Lower Ordovician plutonism in the northern part of Sierra de Macón, Salta province
In northern Sierra de Macón, in the western sector of the Puna, is a plutonic complex composed dominantly of granodiorites, which grade in composition to tonalites and granites. Toward the west and north of the range, mafic microgranular enclaves are common, as well as pseudo-dikes and pseudo-intrus...
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2002
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00044822_v57_n2_p173_Koukharsky http://hdl.handle.net/20.500.12110/paper_00044822_v57_n2_p173_Koukharsky |
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paper:paper_00044822_v57_n2_p173_Koukharsky2023-06-08T14:25:35Z Lower Ordovician plutonism in the northern part of Sierra de Macón, Salta province Arc magmatism Lower Ordovician plutonism Puna granitoids island arc Ordovician petrogenesis plutonism Argentina In northern Sierra de Macón, in the western sector of the Puna, is a plutonic complex composed dominantly of granodiorites, which grade in composition to tonalites and granites. Toward the west and north of the range, mafic microgranular enclaves are common, as well as pseudo-dikes and pseudo-intrusive bodies of metavolcanic rocks, suggesting levels near to the roof of the magma chambers. K/Ar and Rb/Sr ages determined in the 1970's gave an Upper Proterozoic age for the intrusion, whereas other authors considered it to be Ordovician, Silurian or Carboniferous, on the basis of regional correlations. In this study, an Ar/Ar hornblende age determined on one of the more primitive and fresh rocks, was 482.7 «7.8 Ma (Ordovician). On the basis of petrographical characteristics that indicate an epizonal location, this age is considered close to the age of the intrusion. The lithological association and geochemical data point to a volcanic calc-alkaline arc setting. Low-grade alteration (chloritic-sericitic) and structural deformation of the last crystallized minerals (potassic feldspar and quartz), present in all the studied samples, are interpreted as being associated with compressive stress related to the Ocloyic orogeny. These conclusions are at variance with the extensional anorogenic environment proposed by previous authors for the origin of these plutonic rocks. 2002 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00044822_v57_n2_p173_Koukharsky http://hdl.handle.net/20.500.12110/paper_00044822_v57_n2_p173_Koukharsky |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Arc magmatism Lower Ordovician plutonism Puna granitoids island arc Ordovician petrogenesis plutonism Argentina |
| spellingShingle |
Arc magmatism Lower Ordovician plutonism Puna granitoids island arc Ordovician petrogenesis plutonism Argentina Lower Ordovician plutonism in the northern part of Sierra de Macón, Salta province |
| topic_facet |
Arc magmatism Lower Ordovician plutonism Puna granitoids island arc Ordovician petrogenesis plutonism Argentina |
| description |
In northern Sierra de Macón, in the western sector of the Puna, is a plutonic complex composed dominantly of granodiorites, which grade in composition to tonalites and granites. Toward the west and north of the range, mafic microgranular enclaves are common, as well as pseudo-dikes and pseudo-intrusive bodies of metavolcanic rocks, suggesting levels near to the roof of the magma chambers. K/Ar and Rb/Sr ages determined in the 1970's gave an Upper Proterozoic age for the intrusion, whereas other authors considered it to be Ordovician, Silurian or Carboniferous, on the basis of regional correlations. In this study, an Ar/Ar hornblende age determined on one of the more primitive and fresh rocks, was 482.7 «7.8 Ma (Ordovician). On the basis of petrographical characteristics that indicate an epizonal location, this age is considered close to the age of the intrusion. The lithological association and geochemical data point to a volcanic calc-alkaline arc setting. Low-grade alteration (chloritic-sericitic) and structural deformation of the last crystallized minerals (potassic feldspar and quartz), present in all the studied samples, are interpreted as being associated with compressive stress related to the Ocloyic orogeny. These conclusions are at variance with the extensional anorogenic environment proposed by previous authors for the origin of these plutonic rocks. |
| title |
Lower Ordovician plutonism in the northern part of Sierra de Macón, Salta province |
| title_short |
Lower Ordovician plutonism in the northern part of Sierra de Macón, Salta province |
| title_full |
Lower Ordovician plutonism in the northern part of Sierra de Macón, Salta province |
| title_fullStr |
Lower Ordovician plutonism in the northern part of Sierra de Macón, Salta province |
| title_full_unstemmed |
Lower Ordovician plutonism in the northern part of Sierra de Macón, Salta province |
| title_sort |
lower ordovician plutonism in the northern part of sierra de macón, salta province |
| publishDate |
2002 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00044822_v57_n2_p173_Koukharsky http://hdl.handle.net/20.500.12110/paper_00044822_v57_n2_p173_Koukharsky |
| _version_ |
1768542577400741888 |