Publication: Determinación de las condiciones P-T del metamorfismo
Famatiniano (470 - 430 Ma) mediante pseudosección en
metabasitas de la Sierra del Espinal (Sierras Pampeanas
Occidentales, Argentina)
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Publication Date
2012
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Sociedad Geológica de España
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Abstract
En las sierras de Maz y El Espinal (La Rioja,Argentina) el basamento polimetamórfico (terreno Maz) registra tres eventos metamórficos: M1 y M2, grenvillianos (entre 1,05 - 1,2 Ga); M3, famatiniano (470 a 430 Ma). En el Dominio de Ramaditas de la Sierra de Espinal afloran anfibolitas granatíferas derivadas de diques basálticos emplazados en sedimentos post-grenvillianos, por lo que su metamorfismo es exclusivamente famatiniano. Ello permite resolver los efectos de M3. En estas rocas se han calculado las condiciones P-T mediante intersección de isopletas en una pseudosección en el sistema NCFMASH, obteniéndose valores de 655 ± 60 ºC y 7,2 ± 0,6 kbar. El metamorfismo fue de tipo Barroviense e implicó engrosamiento cortical significativo
In the Sierras de Maz and El Espinal (La Rioja, Argentina) a polymetamorphic basement (Maz terrane) records three metamorphic events:M1 and M2, Grenvillian (at ca. 1.05 and 1.2 Ga); M3, Famatinian (470 - 430 Ma). In the Ramaditas Domain in the Sierra de El Espinal, garnet amphibolites occur, which originated from basaltic dikes that intruded post-Grenvillian sediments. Therefore they underwent Famatinian metamorphism only. This allows to discriminate the effects of the M3 event, that overprints the Grenvillian ones. Pressure and peak temperature have been calculated by isopleth intersection on a P-T pseudosection in the system NCFMASH yielding values of 655 ± 60 ºC and 7.2 ± 0.6 kbar. Metamorphism was of Barrovian type and involved remarkable crustal thickening
In the Sierras de Maz and El Espinal (La Rioja, Argentina) a polymetamorphic basement (Maz terrane) records three metamorphic events:M1 and M2, Grenvillian (at ca. 1.05 and 1.2 Ga); M3, Famatinian (470 - 430 Ma). In the Ramaditas Domain in the Sierra de El Espinal, garnet amphibolites occur, which originated from basaltic dikes that intruded post-Grenvillian sediments. Therefore they underwent Famatinian metamorphism only. This allows to discriminate the effects of the M3 event, that overprints the Grenvillian ones. Pressure and peak temperature have been calculated by isopleth intersection on a P-T pseudosection in the system NCFMASH yielding values of 655 ± 60 ºC and 7.2 ± 0.6 kbar. Metamorphism was of Barrovian type and involved remarkable crustal thickening