Minero-petrographical features of weathering profiles in Calabria, southern Italy

The paper reports interdisciplinary research of weathering profile stages on gneiss with regard to tectonicand landscape evolutions of the western Sila Grande Massif (Southern Italy). The outcropping rocks consistof medium- to coarse-grained biotite–garnet and sillimanite gneiss (BGS-G), and medium- to coarsegrainedbiotite–muscovite migmatitic gneiss (M-G). The BGS-G rocks are fractured and weathered witheither massive or foliated texture, whereas the M-G rocks are intensely weathered and fractured with a massivetexture and frequent pegmatite veins. Petrographical and mineralogical variations show that bothgneissic rocks (BGS-G and M-G samples) underwent weathering processes characterized by a progressivechemical attack on the labile minerals with generation of neoformed minerals and substitution of the originalrock fabric. The weathering processes produced phyllosilicates and Fe-oxides; neoformed clay minerals andferruginous products replaced feldspars and biotite during the most advanced weathering stage. Microfracturesand morphological variations occur on the original rock and, thereby, affect the surrounding landscapeprocesses. The weathering profile mineralogy and rock textures viewed in the context of landscape evolutionprovide useful insights into the widespread slope movement phenomena in the Sila Grande Massif gneiss.