Data/hora: 10/06/2024 05:44:36

Provedor de dados: | 42
País: | Brazil
Título: | Geology, petrography and geochemistry of the A-type granites from the Morro Redondo Complex (PR-SC), southern Brazil, Graciosa Province
Autores: | VILALVA,FREDERICO C.J.; VLACH,SILVIO R.F.
Data: | 2014-03-01
Ano: | 2014
Palavras-chave: | A-type granites; Geochemistry; Petrography; Graciosa Province; Mineralogy; Morro Redondo Complex.
Resumo: | The Morro Redondo Complex is one of the most important occurrences of the Graciosa A-type Province, southern Brazil. It consists of the Papanduva and Quiriri granitic plutons and a contemporaneous bimodal volcanic association. The Papanduva Pluton includes massive and deformed peralkaline alkali-feldspar granites with Na-Ca and Na-amphiboles and clinopyroxenes. The deformed types are the most evolved rocks in the province and carry rare ‘agpaitic’ minerals, some being described for the first time in granites from Brazil. The larger Quiriri Pluton comprises massive, slightly peraluminous, biotite syeno- and monzogranites with rare Ca-amphibole. Biotite compositions are relatively homogeneous, whereas sodic amphiboles and clinopyroxenes show increasing Na and Fe3+ evolving paths. The Morro Redondo granites are ferroan, with high SiO2, alkalis and HFSE contents; the peralkaline types registering the highest fe#. LILE and HFSE abundances increase with the agpaitic index and the most evolved are HHP granites, with radiogenic heat production up to 5.7 µWm–3. Geothermobarometric estimates indicate emplacement under low pressures (∼100 MPa), at temperatures up to 850-800 °C, and relatively reduced (QFM) and oxidized (+1 &lt; ΔQFM &lt; +3) environments for the Papanduva and Quiriri Plutons, respectively. In both cases, melts evolved to relatively high oxidation states upon crystallization progress.
Tipo: | Info:eu-repo/semantics/article
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652014000100085
Editor: | Academia Brasileira de Ciências
Relação: | 10.1590/0001-37652014108312
Formato: | text/html
Fonte: | Anais da Academia Brasileira de Ciências  v.86 n.1 2014
Fonte: | info:eu-repo/semantics/openAccess