Post-rift extensional tectonics at the edge of a carbonate platform: insights from the Middle Jurassic-Early Cretaceous Monte Giano stratigraphic record (central Apennines, Italy)

Abstract

A new interpretation of the Middle Jurassic-Early Cretaceous paleogeographic evolution of the NW sector of the Latium-Abruzzi carbonate platform facing the Umbria-Marche Basin is proposed, based on Monte Giano area (central Apennines, Italy). During Late Triassic-early Bajocian time, the area was characterized by shallow water sedimentation. Inner and marginal carbonate platform deposits are overlain by pelagic deposits (Posidonia level), early Bajocian p.p. in age. This unconformity testifying the sudden drowning of the Monte Giano area, while shallow water sedimentation persisted in the remaining sectors of the carbonate platform. The Posidonia level is paraconformably overlain by distal slope deposits of the Velino Gorge limestones Formation, Kimmeridgian p.p.-Tithonian p.p. in age. Therefore, a 12Ma gap is recorded as in the Umbria-Marche Basin pelagic carbonate platforms. An extensional Bajocian tectonic phase, possibly related to the Piemont-Ligurian Ocean opening coupled with rheologic differences at the basin/platform boundary, drastically changed the regional paleogeography causing the breakup and the drowning of the NW sector of the Latium-Abruzzi carbonate platform and the creation of a large flat-topped pelagic carbonate platform. The estimate offset of the early Bajocian fault is around 300-350m. The Velino Gorge limestones fm. pass laterally and vertically to the Upper Tithonian platform-margin reef complex of the Ellipsactinia limestones fm.; these units constitute a shallowing and coarsening upward sequence and levelled the paleobathymetric gradient created by the Bajocian extension. The progradation of the Latium-Abruzzi carbonate platform continued during Early Cretaceous time. These results have strong implications on the tectonic and paleogeographic evolution of the major domains of the central Apennines.

Stratigraphy and tectonic evolution of a portion of the Simbruini-Ernici Mountains (Central Apennines - Italy): review and new data from detailed geological mapping

“…This progradation evened out the Filettino-La Monna Basin during the Toarcian. A comparable basin-margin evolution is recorded by Middle-Upper Jurassic pelagic-to-shallow water deposits at the northern edge of the Latium-Abruzzi platform (Capotorti and Muraro, 2021).…”

The Tethyan and Tyrrhenian margin record of the Central Apennines: a guide with insights from stratigraphy, tectonics, and hydrogeology

“…Around them, base-of-slope to basinal domains are present (e.g., Gran Sasso: Adamoli et al, 1978;Cardello & Doglioni, 2015;Maiella: Rusciadelli & Di Simone, 2007;Brandano et al, 2016a). During the Cretaceous, rimmed inner platforms were affected by areal shrinking as Scaglia pelagic basins developed (Tavani et al, 2015;Cipriani & Bottini, 2019;Capotorti & Muraro, 2021;Cardello et al, 2021;Vitale & Ciarcia, 2021). During the Neogene, those tectono-stratigraphic passive margin units were accreted on top of the subducting Adria plate during the progressive E/NE-ward migration of frontal thrusts (Boccaletti & Guazzone, 1974;Malinverno & Ryan, 1986;Bigi et al, 1992) and the related forebulge to foredeep and wedge-top deposits (e.g., Royden et al, 1987;Carminati et al, 2007;Vitale & Ciarcia, 2013;Fabbi et al, 2014;Cardello et al, 2021).…”