A DETRITAL ZIRCON PROVENANCE STUDY OF THE MARNOSO-ARENACEA FORMATION, NORTHERN APPENNINES, ITALY

The Marnoso-arenacea (Langhian-Serravallian) formation (MAF) in central Italy is a well-studied and well documented geologic formation. Its great neighbor to the north, the Alps mountain belt, is one of the most studied geologic features on planet earth. Likewise, the MAF has received much attention in terms of sedimentology, and is well-known for its turbiditic successions. In terms of provenance however, the MAF has not had any detrital zircon work. The goal of this research is to improve our understanding of the provenance using detrital zircon U-Pb data from the sandstones in the MAF. In stratigraphic order, our samples are from the base of the sandstones that lie directly above the Aquadelto, Contessa, Casaglia, Bedetta, and Paretaio mass transport complexes (MTCs). These sandstones are thickly-bedded that are either poorly-lithified fine grained sandstones; massive, well-sorted, medium-grained sandstones; or poorly-sorted coarse-grained sandstones. Data sets collected indicate groups of zircon ages around 32 Ma, 285 Ma, and 460 Ma. Furthermore, using an age pick program we found that proportions of these dates are 20%, 17%, and 10% respectively. A noteworthy feature is the absence of any grains younger than 80 Ma in the Contessa key marker bed. In every sample there is a small amount of Precambrian grains. Based on previous work, the overwhelming source of detrital material to the MAF is the central Italian Alps. However, based on our data, an additional contributor is the western Alps.