Vilalva, F. C. J., Vlach, S. R. F. (2010) Major- and trace-element composition of REE-rich turkestanite from peralkaline granites of the Morro Redondo Complex, Graciosa Province, south Brazil. Mineralogical Magazine, 74 (4) 645-658 doi:10.1180/minmag.2010.074.4.645
Reference Type | Journal (article/letter/editorial) | ||
---|---|---|---|
Title | Major- and trace-element composition of REE-rich turkestanite from peralkaline granites of the Morro Redondo Complex, Graciosa Province, south Brazil | ||
Journal | Mineralogical Magazine | ||
Authors | Vilalva, F. C. J. | Author | |
Vlach, S. R. F. | Author | ||
Year | 2010 (August) | Volume | 74 |
Page(s) | 645-658 | Issue | 4 |
Publisher | Mineralogical Society | ||
DOI | doi:10.1180/minmag.2010.074.4.645Search in ResearchGate | ||
Mindat Ref. ID | 244094 | Long-form Identifier | mindat:1:5:244094:5 |
GUID | a8dc7ad4-57d0-4b6f-9ea1-3193d4baad7d | ||
Full Reference | Vilalva, F. C. J., Vlach, S. R. F. (2010) Major- and trace-element composition of REE-rich turkestanite from peralkaline granites of the Morro Redondo Complex, Graciosa Province, south Brazil. Mineralogical Magazine, 74 (4) 645-658 doi:10.1180/minmag.2010.074.4.645 | ||
Plain Text | Vilalva, F. C. J., Vlach, S. R. F. (2010) Major- and trace-element composition of REE-rich turkestanite from peralkaline granites of the Morro Redondo Complex, Graciosa Province, south Brazil. Mineralogical Magazine, 74 (4) 645-658 doi:10.1180/minmag.2010.074.4.645 | ||
Abstract/Notes | AbstractTurkestanite, a rare Th- and REE-bearing cyclosilicate in the ekanite–steacyite group was found in evolved peralkaline granitesfrom the Morro Redondo Complex, south Brazil. It occurswith quartz, alkali feldspar and an unnamed Y-bearing silicate. Electron microprobe analysis indicates relatively homogeneous compositions with maximum ThO2, Na2O and K2O contentsof 22.4%, 2.93% and 3.15 wt.%, respectively, and significant REE2O3 abundances(5.21 to 11.04 wt.%). The REE patterns show enrichment of LREE over HREE, a strong negative Eu anomaly and positive Ce anomaly, the latter in the most transformed crystals. Laser ablation inductively coupled plasma mass spectrometry trace element patterns display considerable depletions in Nb, Zr, Hf, Ti and Li relative to whole-rock sample compositions. Observed compositional variations suggest the influence of coupled substitution mechanisms involving steacyite, a Na-dominant analogue of turkestanite, iraqite, a REE-bearing end-member in the ekanite–steacyite group, ekanite and some theoretical end-members. Turkestanite crystals were interpreted as having precipitated during post-magmatic stages in the presence of residual HFSE-rich fluidscarrying Ca, the circulation of which wasenhanced by deformational events. |
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