Caracterização química de cromitas nos maciços de cromínia e mairipotaba, goiás, Brasil


Autoria(s): Angeli, Nélson; Beltran Navarro, Guillermo Rafael; Farias Vlach, Silvio Roberto; Zanardo, Antenor
Contribuinte(s)

Universidade Estadual Paulista (UNESP)

Data(s)

27/05/2014

27/05/2014

01/03/2010

Resumo

Metaultramafic bodies tectonically emplaced within the metasedimentary sequence of the Araxá Group are associated with an ophiolitic melange in southeast Goiás. In the region of Crominia - Mairipotaba, they occur as lenticular bodies aligned E-W. Cumulate textures and geochemical data indicate that the parent rocks had harzburgitic to dunitic compositions. Relicts of primary crystals of olivine and orthopyroxene are suggestive of amphibolite facies metamorphic re-equilibration fabrics, even though the paragenesis and mineral associations of these metaultramafic rocks are typical of greenschist facies (T < 550°C and P = 5.5 kbar). The chromitites exhibit massive to breccioid structure and pull-apart texture, with chromite crystals around 0.5 mm in size. Chromite concentrations in the chromitite levels reach 70 to 85% by volume of the rock. The crystals are dispersed in the matrix, which is composed essentially of serpentine, and subordinately of chlorite and talc. The textures and geochemical data (Cr 2O 3 x TiO 2 and Mg x Cr ratios present in the chromitite) are similar to those observed in ophiolitic complexes. Hence, they correspond to allochthonous bodies (Alpine type) associated with an ophiolitic mélange.

Formato

87-99

Identificador

http://dx.doi.org/10.5327/Z1519-874X2010000100007

Geologia USP - Serie Cientifica, v. 10, n. 1, p. 87-99, 2010.

1519-874X

http://hdl.handle.net/11449/71594

10.5327/Z1519-874X2010000100007

2-s2.0-77951069166

2-s2.0-77951069166.pdf

Idioma(s)

por

Relação

Geologia USP: Serie Cientifica

Direitos

openAccess

Palavras-Chave #Araxá group #Brasilia belt #Chromite #Mineral chemistry #Ophiolitic melange #chemical composition #chromite #chromitite #concentration (composition) #geochemistry #greenschist facies #melange #olivine #ophiolite #orthopyroxene #paragenesis #parent body #source rock #Brasilia Belt #Brazil #Goias
Tipo

info:eu-repo/semantics/article