Petrography of Paleogene turbiditic sedimentation in northeastern Italy

The Paleogene turbiditic sedimentation in the eastern Southern Alps represents the sedimentary response to tectonic activity related to the Mesoalpine phase, which involved the surrounding chains from Paleocene time onward. Field and petrographic analyses have allowed us to classify these turbiditic successions as multisource deposits, as demonstrated by the common presence of allochemical, mainly bioclastic detritus, associated with different types of terrigenous arenites. For all units, field data suggest more proximal sources for allochemical supply and distal sources for terrigenous material, characterized by the presence of chert, carbonate rocks, and metamorphic rock fragments. All the investigated successions display transparent heavy mineral associations, marked by the common presence of chrome spinel, alkaline amphibole, staurolite, epidote, and zoisite, which point to similar metamorphic sources. The location of the source of metamorphic rock fragments is uncertain, but inputs from the internal Dinaric belt are possible. The source of the allochemical detritus was located in the nearby reactivated Friuli Platform.