Abstract Peraluminous granites and trondhjemites make up small plutonic bodies intruded into high-grade paragneisses in the Peloritani Mountains, marking the beginning of late Variscan granitoid magmatism in southernmost Italy. The granites range from low-Ca monzogranites to alkali feldspar granites, while the trondhjemites vary from trondhjemites s.s . to low-Ca trondhjemites. Relatively high radiogenic ( 87 Sr/ 86 Sr) i ratios (mostly from 0.7073 to 0.7125) and negative ε Nd values (mostly from −5.66 to −8.73) point to crustal sources for all the granitoids. Major and trace element compositions indicate an absence of genetic relationships between the trondhjemites s.s . and the low-Ca granitoids, but possible relationships between the low-Ca trondhjemites and the granites. All of the studied granitoids have near-pure melts compositions, consistent with H 2 O-fluxed and dehydration melting of metasediments for the trondhjemites and the granites, respectively. However, the unusual compositions of the low-Ca trondhjemites and microstructural evidence in these rocks for pervasive subsolidus replacement of magmatic feldspars by secondary sodic plagioclase indicate that they were derived instead from metasomatic alteration of the granites. Thus, water may be involved in the production of trondhjemites in two different ways, driving water-fluxed melting in the magma source and driving alkali metasomatism at the sites of granite emplacement in the upper crust.

Abstract A strain gradient was mesoscopically recognized in sheared leucogneisses cropping out near Mount Montalto (Calabria, southern Italy) in the Aspromonte–Peloritani Unit on the basis of field observations. In order to investigate the relationship between textural and physical anisotropy, a microstructural and petrophysical study was carried out on selected mylonites exhibiting different stages of deformation. The main mineral assemblage is Qtz+Pl+Kfs+Wm, displaying S – C and shear-band textures; mica-fish and ribbon-like quartz are widespread. As strain increases K-feldspar, biotite and premylonitic low phengite white mica transformed to synmylonitic high phengite white mica and quartz, accompanied by an increasing albitization. Different quartz c -axis patterns are ascribable to non-coaxial progressive deformation; we suggest that deformation proceeded under greenschist- up to amphibolite-facies conditions owing to a local increase in shearing temperature. Laboratory seismic measurements were carried out on sample cubes (43 mm edged) cut according to the structural frame (foliation, lineation) of the rock. At 400 MPa and room temperature the averages of compressional ( V p ) and shear-wave velocities ( V s ) are very similar: 5.70–5.91 and 3.36–3.55 km s −1 , respectively. Seismic anisotropy and shear-wave splitting are related to the modal amounts of constituent minerals (in particular mica) and their crystallographic preferred orientation. Importantly, anisotropy is lowest in the most strained rock.