Phosphate-bearing pegmatites hosted in the crystalline basement of the Southern Alps have been described at Brissago (Vignola et al., 2008) and close to the village of Piona (Vignola & Diella, 2007; Vignola et al., 2008; Vignola et al., 2010). All these pegmatites are hosted by high grade sillimaniteand garnet-bearing micaschists. The pegmatite dikes consist of plagioclase and quartz with almandine, schorl and muscovite as common accessories. These pegmatites can be classified as beryl-columbitephosphate subtype applying the classification of ?erný & Ercit (2005). Age determinations on zircon, feldspar and monazite-(Ce) evidenced two different ages of crystallization; one in Mid Triassic (Brissago, 242 Ma, Vignola et al. 2008) and one in Upper Triassic (Malpensata, 215 Ma, Vignola unpublished data). Other minor occurrences of graftonite-bearing pegmatites are located in the Strona Valley (Verbano-Cusio-Ossola province, Piedmont, Italy; Vignola unpublished data). In the following we describe the phosphate- and chrysoberyl-bearing pegmatite located close to Malga Garbella in the Rabbi commune, Trento Province (central-eastern Alps). The rock-forming and accessory minerals of the pegmatite were investigated by means of direct observation of hand specimen, SEM-BSE images, WDS electron microprobe analysis and X-ray diffraction.
The chrysoberyl- and phosphate-bearing granitic pegmatite of Malga Garbella, Val di Rabbi, Trento province, Italy.
Pietro Vignola;
2017
Abstract
Phosphate-bearing pegmatites hosted in the crystalline basement of the Southern Alps have been described at Brissago (Vignola et al., 2008) and close to the village of Piona (Vignola & Diella, 2007; Vignola et al., 2008; Vignola et al., 2010). All these pegmatites are hosted by high grade sillimaniteand garnet-bearing micaschists. The pegmatite dikes consist of plagioclase and quartz with almandine, schorl and muscovite as common accessories. These pegmatites can be classified as beryl-columbitephosphate subtype applying the classification of ?erný & Ercit (2005). Age determinations on zircon, feldspar and monazite-(Ce) evidenced two different ages of crystallization; one in Mid Triassic (Brissago, 242 Ma, Vignola et al. 2008) and one in Upper Triassic (Malpensata, 215 Ma, Vignola unpublished data). Other minor occurrences of graftonite-bearing pegmatites are located in the Strona Valley (Verbano-Cusio-Ossola province, Piedmont, Italy; Vignola unpublished data). In the following we describe the phosphate- and chrysoberyl-bearing pegmatite located close to Malga Garbella in the Rabbi commune, Trento Province (central-eastern Alps). The rock-forming and accessory minerals of the pegmatite were investigated by means of direct observation of hand specimen, SEM-BSE images, WDS electron microprobe analysis and X-ray diffraction.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.