| Autor: |
Renato Henrique-Pinto, Valdecir de Assis Janasi, Ginaldo Ademar da Cruz Campanha |
| Jazyk: |
English<br />Portuguese |
| Rok vydání: |
2018 |
| Předmět: |
|
| Zdroj: |
Geologia USP. Série Científica, Vol 18, Iss 2 (2018) |
| Druh dokumentu: |
article |
| ISSN: |
2316-9095 |
| DOI: |
10.11606/issn.2316-9095.v18-125793 |
| Popis: |
We present new in situ geochronological data of controversial silicic metavolcanic rocks from the lower terrigenous-metavolcanic sequence of the São Roque Group, Ribeira Belt, confirming that they are older than the rocks of higher-metamorphic grade sequences of the Serra do Itaberaba Group. The age of the Polvilho meta-trachydacite was established at 1760 ± 17 Ma, furthermore the results suggest that the bi-modal volcanism of the Boturuna Formation has parent melts from an old (Archean to Paleoproterozoic) continental crust that was melted in a within-plate environment. Trace-element chemistry of zircon, suggests similarities with high-temperature melts (T Zrsat = 900–915ºC) similar to A-type granites (high negative EuN/EuN* and moderate positive CeN/CeN*) from continental sources under reducing conditions. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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