Polyphase out-of-sequence thrusting and occurrence of marble detritus within the wedge-top basin deposits in the Mt. Massico (southern Apennines): insights into the late Miocene tectonic evolution of the central Mediterranean

Development of an Intrawedge Tectonic Mélange by Out‐of‐Sequence Thrusting, Buttressing, and Intraformational Rheological Contrast, Mt. Massico Ridge, Apennines, Italy

“…They consist of turbiditic sequences characterized by fine‐grained siliciclastic sandstones deposited within a deep‐to‐shallow water environment (e.g., Critelli et al, ; Milli & Moscatelli, ) and are lithologically different from the clastic succession of the Mt. Massico ridge, which deposited in a wedge‐top basin environment (e.g., Vitale et al, ; Figures c and c–h).…”

“…Above the hemipelagic marls, the sedimentary succession evolves into the Tortonian‐lower Messinian (Bergomi et al, ; Vitale et al, ) siliciclastic/carbonaticlastic deposits of the Caiazzo Fm. (hereafter clastic deposits, Figure c), which are interpreted as wedge‐top basin deposits (Vitale et al, ).…”

“…Above the hemipelagic marls, the sedimentary succession evolves into the Tortonian‐lower Messinian (Bergomi et al, ; Vitale et al, ) siliciclastic/carbonaticlastic deposits of the Caiazzo Fm. (hereafter clastic deposits, Figure c), which are interpreted as wedge‐top basin deposits (Vitale et al, ). The clastic deposits are made up of massive‐to‐bedded siliciclastic sandstones with clayey and marly interbeds (Figure b), polymictic breccias/conglomerates characterized by Mesozoic‐Cenozoic carbonate and siliciclastic clasts (up to a few cubic decimeters in volume), including also clasts of volcanic, intrusive, and metamorphic rocks (Figures c–f) and calcarenite interbeds (Figure S1d; Cestari, ; Sgrosso, ).…”

“…Olistoliths consist of both Mesozoic‐Cenozoic limestones and rocks that are not exposed in the local sedimentary succession, hereafter named exotic olistoliths (Cestari, ; Sgrosso, ). Exotic olistoliths consist of the following: (1) marbles and recrystallized carbonates (Figures f–h; Di Girolamo et al, ; Vitale et al, ); (2) volcanic, intrusive, and metamorphic rocks (Bergomi et al, ; Cestari, , Di Girolamo et al, ); and (3) deep basinal Paleocene limestone blocks (Cestari, ; Sgrosso, ). By comparing our original geological field mapping with published geological map (Servizio Geologico d'Italia, ), we estimate that the total thickness of the upper Tortonian‐lower Messinian succession is ~800 m.…”

“…In this work, we combine geological mapping at 1:10,000 scale and structural analyses with paleothermal indicators (mixed layers illite‐smectite, I‐S) and U‐Pb dating of calcite veins and slickenfibers from S‐CC' tectonites to reconstruct the tectonic evolution, the maximum overburden, and the deformation mechanisms of an intrawedge tectonic mélanges in the Mt. Massico ridge area (Vitale et al, ). This area is located in the inner part (Tyrrhenian side) of the central southern Apennine accretionary wedge (central Italy; Figure ).…”