NACARENIOBSITE-(Ce) AND BRITHOLITE-(Ce) IN PERALKALINE GRANITES FROM THE MORRO REDONDO COMPLEX, GRACIOSA PROVINCE, SOUTHERN BRAZIL: OCCURRENCE AND COMPOSITIONAL DATA

Britholite, monazite, REE carbonates, and calcite: Products of hydrothermal alteration of allanite and apatite in A-type granite from Stupné, Western Carpathians, Slovakia

“…Occurrences of primary magmatic BGM are limited to peralkaline granites and syenite pegmatites (e.g., Griffin et al, 1979;Larsen, 1996;Pekov et al, 2007Pekov et al, , 2011Vilalva et al, 2013) or peralkaline rhyolitic rocks (Min et al, 2006;Payette and Martin, 1986). Formation of BGM is usually connected with late-to post-magmatic or hydrothermal alteration processes in diverse alkaline rocks, for example, in alkali syenitic ejecta (Della Ventura et al, 1999), REE-enriched pegmatite segregations (Arden and Halden, 1999), carbonate-amphibole-clinopyroxene rocks (Zaitsev and Chakhmouradian, 2002), REE-rich mineralized zones associated with potassic alkaline to subalkaline volcanic to plutonic rocks (Harlov et al, 2003), or carbonatites and related skarn deposits (Ahijado et al, 2005).…”

“…On the other hand, britholite group minerals isostructural to the apatite group are relatively rare in nature, and their occurrences are linked especially to late-magmatic crystallization or subsolidus alteration of primary minerals in alkali-rich granites, monzonites, (nepheline) syenites, and their pegmatites, carbonatites, and dikes and metamorphic rocks related to them (e.g., Ahijado et al, 2005;Arden and Halden, 1999;Della Ventura et al, 1999;MacDonald et al, 2013;Pekov et al, 2007;Smith et al, 2002;Vilalva et al, 2013).…”

The crystallization of shoshonitic to peralkaline trachyphonolitic magmas in a H2O–Cl–F-rich environment at Ischia (Italy), with implications for the feeder system of the Campania Plain volcanoes

“…11) and elsewhere (cf. Macdonald et al, 2013;Melluso et al, 2010aMelluso et al, , 2011Melluso et al, , 2012aVilalva et al, 2013 …”

Geology, petrography and geochemistry of the A-type granites from the Morro Redondo Complex (PR-SC), southern Brazil, Graciosa Province

“…Fluorite, astrophyllite, titanite, aenigmatite and some ilmenite are common accessory minerals in both facies. Zircon and late magnetite appear only in the deformed 'cataclastic' facies, while combinations of late to post-magmatic 'agpaitic' Ti-, Zr-, and REEbearing rare silicates and oxides, such as narsarsukite, neptunite, elpidite and other (Na,K)-zirconosilicates, britholite, turkestanite, nacareniobsite, brookite and some as-yet unidentified minerals, are widespread in the deformed 'protomylonitic' facies, even in miarolitic cavities and vugs (Vilalva and Vlach 2010, Vilalva et al 2013, Vlach and Vilalva 2007.…”

“…These correlate positively with the peralkalinity grade (as measured by the Agpaitic Index), a geochemical signature that led to the crystallization of rare 'agpaitic' assemblages in the more evolved facies, as evidenced by the Ti-, Zr-and REE-rich unusual accessory mineralogy, formed during late to post-magmatic stages. It is worth mentioning that several among these minerals, including aenigmatite, neptunite, narsarsukite, Na-K zirconosilicates, nacareniobsite, turkestanite, as well as to date poorly studied and/or unidentified minor phases (Vilalva and Vlach 2010, Vilalva et al 2013, Vlach and Vilalva 2007 are described for the first time in peralkaline granites from Brazil. Such mineralogical and textural features, along with geochemical data, indicate that the more evolved the liquids are, the higher the Agpaitic Index will be, as well as the Na 2 O, Fe 2 O 3 T , LILE and HFSE abundances.…”