Zr- AND Ba-RICH MINERALS FROM THE PONTE NOVA ALKALINE MAFIC-ULTRAMAFIC MASSIF, SOUTHEASTERN BRAZIL: INDICATION OF AN ENRICHED MANTLE SOURCE
Contribuinte(s) |
UNIVERSIDADE DE SÃO PAULO |
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Data(s) |
20/10/2012
20/10/2012
2009
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Resumo |
Zirconium- and Ba-rich minerals are found in gabbroic rocks from the Ponte Nova alkaline mafic-ultramafic massif in southeastern Brazil. The unusual mineralogical assemblage includes zirconolite, baddeleyite, Ba-rich alkali feldspar, and Ba- and Ti-rich biotite. Zirconolite of the Ponte Nova massif has higher levels of Zr (up to 1.172 apfu) than those registered in other terrestrial rocks and a prominent enrichment in the light rare-earth elements. Baddeleyite contains small quantities of Hf, Ti, and Fe. The Ba-rich alkali feldspar and Ba- and Ti-rich biotite contain up to 9.25 and 7.35 wt% BaO, respectively, and the biotite contains up to 12.01 wt% TiO(2). In the different intrusions of the Ponte Nova massif, such an unusual assemblage typifies the residual magma after the crystallization of clinopyroxene and olivine from previously enriched basanitic parental magma. The different trends of enrichments in REE and Th + U found for zirconolite of the intrusions of the Ponte Nova massif provide a better understanding of the variable degrees of enrichment of incompatible elements of the distinct gabbroic bodies. A lithospheric mantle source enriched in incompatible elements by the metasomatic action of volatile-rich fluids and with the presence of phlogopite or amphibole (or both) and other minor accessory phases could explain the presence of the Zr- and Ba-rich minerals in this gabbroic massif. Brazilian Fapesp agency[08/03807-4] Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Brazilian Fapesp agency[07/57461-9] Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Brazilian Fapesp agency[03/00626-5] |
Identificador |
CANADIAN MINERALOGIST, v.47, n.5, p.1087-1103, 2009 0008-4476 http://producao.usp.br/handle/BDPI/30267 10.3749/canmin.47.5.1087 |
Idioma(s) |
eng |
Publicador |
MINERALOGICAL ASSOC CANADA |
Relação |
Canadian Mineralogist |
Direitos |
restrictedAccess Copyright MINERALOGICAL ASSOC CANADA |
Palavras-Chave | #zirconolite #baddeleyite #Ba-rich feldspar #Ba- and Ti-rich biotite #mantle enrichment #Ponte Nova alkaline complex #Brazil #IGNEOUS ROCKS #LITHOSPHERIC MANTLE #CRYSTAL-CHEMISTRY #BADDELEYITE ZRO2 #NORTHEAST CHINA #BARIUM-RICH #ZIRCONOLITE #COMPLEX #PHLOGOPITE #PROVINCE #Mineralogy |
Tipo |
article original article publishedVersion |