Bergell Pluton, Central Alps

Mechanisms and timescales of pluton emplacement

K-feldspar megacrysts entrained in a mafic enclave, Forno region


Recently deglaciated exposure is sufficiently fresh that oxidation of exposed pyrite is still ongoing.


Dense clot of K-feldspar megacrysts, Forno region


Strongly foliated amphibolite xenoliths near the roof of the Bergell pluton, Forno region


Amphibolite xenolith with calc-silicate affinities (note epidote and calcite veins) near the roof of the Bergell pluton, Forno region


Extensive exposure of the megacrystic K-feldspar granodiorite facies of the Bergell Pluton near Albigna


The spire of Piz. Badile, glacially carved out of Bergell granodiorite, Sciora region


A large mafic enclave cut and offset by an aplite dike, Sciora region


Mafic enclave diced by two small magmatic shear zones, Sciora region


Nearly hexagonal mafic enclave, Sciora region


Dust rises from an active rockfall on Piz. Cengalo, Sciora region


An aplite “schlieren-dike” offset across a magmatic shear zone in the transitional “übergangszone” facies of the Bergell pluton, Sciora region


Heterogeneous enclave swarm in the Bergell übergangszone, Sciora region


Poikilitic garnet and tourmaline crystals in a pegmatite dike, Sciora region


Large mafic enclave swarm in the Bergell übergangszone, Sciora region


K-feldspar megacryst entrained and partially resorbed within mafic enclave, Sciora region


Deformed mafic enclaves in an enclave swarm, übergangszone, Sciora region


Ultramafic xenoliths in Bergell granodiorite, altered to anthophyllite and biotite, Sciora region


Dense K-feldspar megacryst clot with biotite-rich interstices, Gianetti region. Ruler is set to 1m for scale.


Large aplite dike, Gianetti region. One of many striking roughly ~240 throughout the Bergell pluton.


Close-packed K-feldspar megacryst clot offset by otherwise-invisible magmatic shear zone, Gianetti region. Note marked concentration of biotite at margin.


Detail of megacryst clot, Gianetti region


Altered ultramafic xenolith, progresively retrograded to chlorite (center) and biotite (rim). Allievi region.


Discordant magmatic contact cut by composite aplite-pegmatite dike, Kima region


Bergell tonalite scattered with ultramafic talus fallen from Monte Disgrazia


Deformed quartz veins following a classic conjugate fracture pair, Ponti region


Discordant contact revealed by strong magmatic fabrics, Ponti region


Sharp contact of Bergell tonalite with shear zone at roof of pluton, Ponti region


Calc-silicate boudin in marble country rock near the roof of the Bergell pluton, Ponti region