Early Proterozoic calc-alkaline and Middle Proterozoic tholeiitic dyke swarms from Central-Eastern Argentina: Petrology, geochemistry, Sr-Nd isotopes and tectonic implications

The Rio de La Plata craton in Argentina (Azul and Tandil regions) is characterized by Early Proterozoic (2·0 Ga) calc-alkaline and Middle Proterozoic (1·6 Ga) tholeiitic dyke swarms intruding the crystalline basement involved in the Transamazonian Orogeny (2·2-1·9 Ga). The calc-alkaline dykes have a...

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Autores principales: Iacumin, M., Piccirillo, E. M., Girardi, V. A. V., Teixeira, W., Bellieni, G., Echeveste, Horacio José, Fernández, Raúl Roberto, Pinese, J. P. P., Ribot, Alejandro Mario
Formato: Articulo
Lenguaje:Inglés
Publicado: 2001
Materias:
Ciencias Naturales
Argentina
Geochemistry
Petrology
Proterozoic dykes
Rio de La Plata craton
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/84392
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-84392
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Naturales
Argentina
Geochemistry
Petrology
Proterozoic dykes
Rio de La Plata craton
spellingShingle Ciencias Naturales
Argentina
Geochemistry
Petrology
Proterozoic dykes
Rio de La Plata craton
Iacumin, M.
Piccirillo, E. M.
Girardi, V. A. V.
Teixeira, W.
Bellieni, G.
Echeveste, Horacio José
Fernández, Raúl Roberto
Pinese, J. P. P.
Ribot, Alejandro Mario
Early Proterozoic calc-alkaline and Middle Proterozoic tholeiitic dyke swarms from Central-Eastern Argentina: Petrology, geochemistry, Sr-Nd isotopes and tectonic implications
topic_facet Ciencias Naturales
Argentina
Geochemistry
Petrology
Proterozoic dykes
Rio de La Plata craton
description The Rio de La Plata craton in Argentina (Azul and Tandil regions) is characterized by Early Proterozoic (2·0 Ga) calc-alkaline and Middle Proterozoic (1·6 Ga) tholeiitic dyke swarms intruding the crystalline basement involved in the Transamazonian Orogeny (2·2-1·9 Ga). The calc-alkaline dykes have andesitic and rhyolitic compositions and trend east-west, whereas the tholeiitic dykes mainly trend N30°W and are represented by basalts with low (0·9-1·7 wt %) and high TiO<SUB>2</SUB> (up to 3·7 wt %). The calc-alkaline dykes have primitive mantle (PM)-normalized trace element patterns enriched in Rb, Ba, K, La, Ce and Nd, and significant negative Nb and Ti anomalies. These dykes are characterized by ε<SUP>t</SUP>(Nd) values of - 3 to - 4, similar to those of the EMI mantle component. Low-TiO<SUB>2</SUB> tholeiitic dykes have low incompatible-element (IE) contents and PM-IE patterns with slightly positive or negative Nb spikes. They have variable ε<SUP>t</SUP>(Nd) values (-0·5 to 12·1), which mainly reflect derivation from a depleted source mantle. High-TiO<SUB>2</SUB> tholeiitic dykes have more enriched IE-PM patterns and are characterized by ε<SUP>t</SUP>(Nd) values (-1·4 to -7·5) typical of an enriched source mantle. Chemical and isotopic data and melting modelling indicate that both calc-alkaline and tholeiitic dykes originated by different melting degrees of a heterogeneous source mantle, the variable IE enrichment of which may have occured in Late Archaean to Early Proterozoic times. The emplacement of the calc-alkaline dykes is associated with the transtensional stage of the Transamazonian Orogeny, whereas the tholeiitic dykes reflect extensional tectonics succeeding the Transamazonian event. The calc-alkaline and tholeiitic dykes are similar in emplacement age and characteristics to metamorphosed granites and volcanic rocks outcropping within the Namaqua fold belts of southwestern Africa (Richtersveld and Witberg-Aggeneys-Gamsberg provinces); this may indicate that the Rio de La Plata craton and southwestern Africa were contiguous in Early-Middle Proterozoic times.
format Articulo
Articulo
author Iacumin, M.
Piccirillo, E. M.
Girardi, V. A. V.
Teixeira, W.
Bellieni, G.
Echeveste, Horacio José
Fernández, Raúl Roberto
Pinese, J. P. P.
Ribot, Alejandro Mario
author_facet Iacumin, M.
Piccirillo, E. M.
Girardi, V. A. V.
Teixeira, W.
Bellieni, G.
Echeveste, Horacio José
Fernández, Raúl Roberto
Pinese, J. P. P.
Ribot, Alejandro Mario
author_sort Iacumin, M.
title Early Proterozoic calc-alkaline and Middle Proterozoic tholeiitic dyke swarms from Central-Eastern Argentina: Petrology, geochemistry, Sr-Nd isotopes and tectonic implications
title_short Early Proterozoic calc-alkaline and Middle Proterozoic tholeiitic dyke swarms from Central-Eastern Argentina: Petrology, geochemistry, Sr-Nd isotopes and tectonic implications
title_full Early Proterozoic calc-alkaline and Middle Proterozoic tholeiitic dyke swarms from Central-Eastern Argentina: Petrology, geochemistry, Sr-Nd isotopes and tectonic implications
title_fullStr Early Proterozoic calc-alkaline and Middle Proterozoic tholeiitic dyke swarms from Central-Eastern Argentina: Petrology, geochemistry, Sr-Nd isotopes and tectonic implications
title_full_unstemmed Early Proterozoic calc-alkaline and Middle Proterozoic tholeiitic dyke swarms from Central-Eastern Argentina: Petrology, geochemistry, Sr-Nd isotopes and tectonic implications
title_sort early proterozoic calc-alkaline and middle proterozoic tholeiitic dyke swarms from central-eastern argentina: petrology, geochemistry, sr-nd isotopes and tectonic implications
publishDate 2001
url http://sedici.unlp.edu.ar/handle/10915/84392
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