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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Micro-structural and compositional variations of hydrothermal epidote-group minerals from a peralkaline granite, Corupa Pluton, Graciosa Province, South Brazil, and their petrological implications

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Author(s):
Vlach, Silvio R. F. [1]
Total Authors: 1
Affiliation:
[1] Univ Sao Paulo, Inst Geociencias, Dept Mineral & Geotecton, BR-05508080 Sao Paulo - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Anais da Academia Brasileira de Ciências; v. 84, n. 2, p. 407-425, JUN 2012.
Web of Science Citations: 8
Abstract

Epidote-group minerals, together with albite, quartz, fluorite, Al-poor and Fe-rich phyllosilicates, zircon, and minor oxides and sulphides, are typical hydrothermal phases in peralkaline alkali-feldspar granites from the Corupa Pluton, Graciosa Province, South Brazil. The epidote-group minerals occur as single crystals and as aggregates filling in rock interstices and miarolitic cavities. They display complex recurrent zoning patterns with an internal zone of ferriallanite-(Ce), followed by allanite-(Ce), then epidote-ferriepidote, and an external zone with allanite-(Ce), with sharp limits, as shown in BSE and X-ray images. REE patterns show decreasing fractionation degrees of LREE over HREE from ferriallanite to epidote. The most external allanite is enriched in MREE. LA-ICP-MS data indicate that ferriallanite is enriched (>10-fold) in Ti, Sr and Ga, and depleted in Mg, Rb, Th and Zr relative to the host granite. Allanite has lower Ga and Mn and higher Zr, Nb and U contents as compared to ferriallanite while epidote is enriched in Sr, U and depleted in Pb, Zr, Hf, Ti and Ga. The formation of these minerals is related to the variable concentrations of HFSE, Ca, Al, Fe and F in fluids remaining from magmatic crystallization, in an oxidizing environment, close to the HM buffer. L-MREE were in part released by the alteration of chevkinite, their main primary repository in the host rocks. (AU)

FAPESP's process: 08/00562-0 - Mantle-crust interaction and the genesis and evolution of the A-type: post-collisional magmatism: geochemical and isotopic records from the Graciosa Province, S-SE Brazil
Grantee:Silvio Roberto Farias Vlach
Support Opportunities: Regular Research Grants