Mineral compositions and magmatic evolution of the calcalkaline rocks of northwestern Sardinia, Italy

Here we report the chemical composition of the main rock-forming minerals (clinopyroxene, orthopyroxene, plagioclase, sanidine, magnetite, ilmenite, olivine, brown mica and amphibole) and whole-rock data covering the entire spectrum of occurring lithotypes.

During Early Miocene northwestern Sardinia was interested by widespread volcanic activity belonging to the calcalkaline to high-K calcalkaline "orogenic" Sardinian cycle. The peak of activity is recorded in the similar to 22-18 Ma time span and it is mostly concentrated along the Fossa Sarda graben, an Oligo-Miocene rift system cutting the western Sardinia from north to south. The northwestern Sardinia volcanic rocks crop out in the districts of Bosa-Alghero, Anglona, Logudoro, Mulargia-Macomer and Ottana graben, ranging in composition from rare high alumina basalt lavas to rhyolitic ignimbrites (welded and unwelded) and lava flows, through basaltic andesites, andesites and dacitic domes, with the most evolved rocks (dacites and rhyolites) being volumetrically predominant.