New stratigraphic and sedimentological investigations on the Middle Eocene–Early Miocene continental successions in southwestern Sardinia (Italy): Paleogeographic and geodynamic implications

Outcrop reservoir analogous and porosity changes in continental deposits from an extensional basin: The case study of the upper Oligocene Sardinia Graben System, Italy

“…The pre-Oligocene basement comprises intensely fractured and weathered metamorphic and magmatic rocks of Ercinian origin (Sowerbutts and Underhill, 1998;Casula et al, 2001;Oggiano et al, 2009), which are overlain by thin middle Eocene continental conglomerates and sandstones of the Cixerri Fm (Barca & Costamagna, 2010). The upper Oligocene continental deposits, known as the Ussana Fm (Cherchi and Montandert, 1984;Eschard, 1987), accumulated during the 'syn-rift stage' (Casula et al, 2001), and were transgressively buried by lower Miocene marine sediments (Simone et al, 2011;.…”

Evolution of a Pyrenean molassic basin in the Western Mediterranean area: The Eocene–Oligocene Cixerri Formation in Southern Sardinia (Italy)

“…Then, during middle Eocene times, Sardinia was affected by the external deformations of the Pyrenean orogeny (Barca & Costamagna, , ). The erosion of this chain feeds continental deposits that form the Cixerri Formation, which is middle Eocene (early Lutetian: Agus & Pecorini, ; Pittau Demelia, ) to early Oligocene in age (Barca & Costamagna, , ; Maxia, ). The conformable to unconformable sealing of this formation is due to the irregular morphology over which the Cixerri Formation was deposited (Pyrenean unconformity).…”

“…The Cixerri Formation is a middle Eocene–early Oligocene terrigenous formation of siltstones, subordinate sandstones, and minor conglomerates with rare intercalations of limestone and lignitiferous clays (Barca & Costamagna, ; Costamagna, ; Maxia, ; Pecorini & Pomesano Cherchi, ; Pittau Demelia, ). The formation may reach a maximum thickness of 350–400 m, and it was deposited in continental to possibly transitional environments (Barca & Costamagna, ; Barca & Palmerini, ). The formation represents the molassic post‐Pyrenean phase of sedimentation in Sardinia (Barca & Costamagna, , ; Cherchi, ), and crops out in the south of the island, where it sometimes rests conformably to unconformably over the Lignitifero Formation, which is a lower Eocene carbonate–siliciclastic lignite‐bearing succession (Barca & Costamagna, , ; Cocozza, De Candia, & Gandin, ; Dreesen et al, ; Fadda, Ottelli, & Perna, ; Fanni, Murru, Salvadori, & Sarria, ; Murru & Salvadori, ; Figure , left).…”

“…The formation may reach a maximum thickness of 350–400 m, and it was deposited in continental to possibly transitional environments (Barca & Costamagna, ; Barca & Palmerini, ). The formation represents the molassic post‐Pyrenean phase of sedimentation in Sardinia (Barca & Costamagna, , ; Cherchi, ), and crops out in the south of the island, where it sometimes rests conformably to unconformably over the Lignitifero Formation, which is a lower Eocene carbonate–siliciclastic lignite‐bearing succession (Barca & Costamagna, , ; Cocozza, De Candia, & Gandin, ; Dreesen et al, ; Fadda, Ottelli, & Perna, ; Fanni, Murru, Salvadori, & Sarria, ; Murru & Salvadori, ; Figure , left). Elsewhere, the Cixerri Formation rests unconformably on low‐grade Variscan metamorphic basement (Carmignani et al, ).…”

Displaced/re-worked rhodolith deposits infilling parts of a complex Miocene multistorey submarine channel: A case history from the Sassari area (Sardinia, Italy)

“…Mesozoic marine limestone and intensely fractured and weathered Middle Eocene continental material locally underwent Oligocene-Miocene deformation (Barca and Costamagna, 2010). Oligocene continental deposits (i.e., the Ussana Formation; Cherchi and Montadert, 1984;Cherchi et al, 2008) accumulated during the first stages of the basement dissection (syn-rift stage according to Casula et al, 2001) mainly in the southern parts of the Sardinia Graben where they pass, through a disconformity surface, to Miocene marine and terrigenous sediments.…”