RENDICONTI DELLA SOCIETÀ ITALIANA DI MINERALOGIA E PETROLOGIA
Abstract
Mineralogical and petrographic studies of gabbros, sediments and serpentinites from an ophiolitic body at Serra del Zanchetto, Italy, are reported. Three groups are studied: 1) a mylonitized gabbro, near a gabbro-serpentinite contact, which contains serpentinite fragments, newly-formed diopsidic clinopyroxene, augite and chlorite, and shows textural characteristics which suggest strong tectonic movements following the serpentinization process; 2) a transformed coarse-grained gabbro, included in the serpentinite, which contains prehnite, after plagioclase and chlorite, after clinopyroxene; the chemical formulae of both minerals and the optical, IR and thermal behaviour of prehnite are given; and 3) fragments of sediment outcropping close to both gabbros and serpentinites. One type seems to be either a diagenetic or weakly metamorphosed arkose; a second, shows similar textures but has chloritized biotite and feldspars replaced by a regularly interstratified chlorite-saponite. The significance of the metasomatic effects of the serpentinization on gabbro xenoliths and arkosic sediments are discussed.
