Interpreting siliciclastic-carbonate detrital modes in Foreland Basin Systems: an example from Upper Miocene arenites of the Central Apennines, Italy. In: Sedimentary Provenance: Petrographic and Geochemical Perspectives

In the centrai Apennines, interacting siliciclastic and carbonate marine clastic wedges filled the foreland basin system during the late Miocene. Conjunction of collisional thrust tectonics and prethrusting norma) faults generated a complex foredeep with intrabasinal structural highs that represented additional source areas to the basin. Detrital modes of the late Miocene centrai Apennines orogenic system range in composition from intrabasinal carbonate to quartzofeldspatholithic and calclithite arenites. The external zone of the foredeep is characterized by hemipelagic deposits, called the Orbulina Mari. Their arenite beds are composed by intrabasinal carbonate, with dominant bioclasts and minor intraclasts, and glauconite derived from an active shallow-marine carbonate source. These hemipelagic deposits are partly coeval with an d partly overlain by siliciclastic turbidites of the Frosinone an d the ArgillosoArenacea Formations, and they represent deposition within local foredeep depocenters. Siliciclastic turbidite sandstones are quartzofeldspatholithic, which documents provenances from metamorphic, plutonic, ophiolitic, and sedimentary rocks. Carbonate intrabasinal structural highs were the main source for carbonate breccias, intrabasinal arenites, and calclithites ofthe Brecce della Renga Formation, the deposits of which are locally interbedded with the coeval siliciclastic turbidite sandstones. Evolution of late Miocene sandstone detrital modes reflected the changing nature of the centrai Apennines thrust belt through time an d the complex architecture of the foreland basin system; it records the history of accretion, deformation of the foredeep, and progressive areai reduction of carbonate-producing areas along with the sedimentary an d structural evolution of local intrabasinal highs.