Sandstone Detrital Modes in the Paleogene Liguride Complex, Accretionary Wedge of the Southern Apennines (Italy)
ABSTRACT The Liguride Complex is an ophiolite-bearing tectonic unit related to westward subduction of the lithosphere of the Neo-Tethys Ocean beneath the European margin. The complex includes a tectonic melange (the Calabro-Lucanian Flysch Unit) containing broken formations of ophiolites and related pelagic and clastic sediments (radiolarian chert, limestone, black shale, and quartzarenite), olistoliths or "tectonic slices" of continental crest (gneiss, granite, and amphibolite), Middle Eocene to Upper Oligocene siliciclastics, and a less deformed turbidite unit (the Saraceno Formation) that caps the succession. Detrital modes of Upper Cretaceous to Lower Miocene sandstones from the Liguride Complex accretionary wedge are grouped into four distinct petrofacies that reflect the geodynamic evolution of Southern Italy. An Upper Cretaceous to Middle Eocene quartzose petrofacies (Q90F9L1) is composed of deep-water quartzarenitic and subarkosic sandstones that appear to have undergone long-distance transport by turbidity currents from the European or African foreland. A Middle Eocene to Upper Oligocene quartzofeldspathic petrofacies (Q62F21L17) was produced by mixing of sediment from ophiolitic and pelagic sedimentary sources with volcanic debris. An Upper Oligocene volcanolithic petrofacies (Q16F24L6054F10L36) is present in the turbidites of the Saraceno Formation. The accretionary-wedge sandstones of the Liguride Complex may record long-distance longitudinal transport for hundreds of kilometers from distal sources (preexisting forelands and volcanic arc) and short-distance transverse transport from local sources (accreted oceanic terranes and collisional-belt terranes), In accretionary-wedge sandstone assemblages, sediments from local and distal sources may be mixed or may record a consistent evolution from one type of transport to the other.