Detrital zircon ages of Oligocene to Miocene sandstone suites of the Southern Apennines foreland basin system, Italy

Abstract

U–Pb spot ages on detrital zircons from turbidite quartzarenites, quartz-feldspathic and volcaniclastic sandstones of the Tufiti di Tusa (TTF), Numidian Flysch (NF), Bifurto (BF), Gorgoglione (GF) and Serra Palazzo (SPF) formations, exposed in southern Italy, were detected to define their provenance signatures aiming to contribute to reconstructing the complex geodynamic evolution of the southern Apennine chain. The deposition ages of these sandstones range from Rupelian (TTF), Burdigalian p.p. -Early Langhian (NF and BF) and Langhian-Serravallian -Early Tortonian (GF and SPF). The detrital zircon ages in each deposit show different clusters. In TTF, the zircon age clusters are: 610 ± 6 Ma; 390 ± 4 Ma; 287 ± 3 Ma; 157 ± 2 Ma; 78 ± 1 Ma and 67 ± 1 Ma; 33 ± 1 Ma. In NF and BF formations, the prevalent zircon ages are clustered at 661 ± 10 Ma, 607 ± 8 Ma and 547 ± 8 Ma. In GF sandstones, the ages of detrital zircons are clustered around 672 ± 28 Ma, 458 ± 9 Ma, 297 ± 8 Ma and 24 ± 1 Ma. The sandstones of SPF contain zircons showing age clusters at 649 ± 10 Ma, 486 ± 7 Ma and 315 ± 5 Ma. Zircons and lithic fragments from TTF display a dominant provenance from Oligocene calc-alkaline effusive products located on western domains of the Mesomediterranean Microplate, and minor detritus from granitoids and metamorphic rocks of Variscan ages. Zircons of NF and BF indicate a provenance of detritus from the African Craton without evidence of Variscan or Alpine signatures. Zircons from GF and SPF show a provenance from both Variscan crystalline basement rocks forming the Alpine chain (Calabria-Peloritani Terranes) and Variscan magmatic and metamorphic rocks unaffected by Alpine tectonics, similar to Sardinia–Corsica (pro-parte) block. In addition, the Oligocene magmatic component dated at 24 Ma in GF sandstones is evidence for the maximum age of sedimentation for these deposits. In light of the recent and preliminary geochronological data acquired, a revised paleogeographic restoration could be inferred for the location of sedimentary basins during the Apennines tectonic evolution. The Rupelian sedimentation age of TTF suggests that the deposition domains of the Numidian sequences and the successive deposits of GF and SPF, were located in a more complex paleogeographic scenario along the orogenic system.