Tectono-sedimentary evolution of southwest Sardinia in the Paleogene: Pyrenaic or Apenninic Dynamic?

The Narcao and Cixerri basins in Southwestern Sardinia are east-west trending basins of Oligocene age. Recent geological mapping combined with structural and stratigraphical analyses support the proposed hypothesis that these basins are very open growth synclines confined within a structural high, delimited by northwest trending dextral strike slip faults. Previously the basins had been interpreted as fault-bounded grabens. The newer revised interpretation is consistent with the existence of NNW trending dextral strike-slip dynamic, related to a north-south shortening which has generated reverse faulting and tight folds in the underlying, pre-synclinal evolution, Eocene succession. This deformation, along with an interfering sub-orthogonal thrust and fold system which affects the Mesozoic sequence, was traditionally linked to the Pyrenean Orogenesis. The Oligocene–Aquitanian shortening, which resulted in the growth synclines and strike-slip faulting, is consistent with the structural development recognised in north-central Sardinia; there structures related to the collision between continental margins that resulted in the Northern Apennines is well documented. Therefore, the Oligocene tectonics of Southwestern Sardinia also must be related to the collision event between the Southern Europe margin (i.e. a crustal sector corresponding to the future Corsica-Sardinia block) and the Adria Plate, which generated the Northern Apennines. Conversely, the previous E-W shortening-related structures must be related to Pyrenean tectonics

Ricostruzione tridimensionale di una zona d'interferenza complessa nell'avampaese varisico della Sardegna SW (miniera di Monteponi)

In this work, we present a 3D model of a zone in the Variscan basemem area in SW Sardinia (Monteponi mine, Iglesias) characterized by the superposition of several folding events, one of which is pre Variscan. For tc build this model we used geological studies, surface data (field data) and sut subsurface data (well logs, mine data)

The Sardinia - Corsica microplate and its role in the Northern Apennine Geodynamics: new insights from the Tertiary intraplate strike - slip tectonics of Sardinia

The behaviour of Sardinia and Corsica within the Alpine-Apennine orogenic events has not been considered in a univocal way; different hypotheses have been proposed, disregarding any eventual effect on the internal structuration of this piece of European crust. Identifying the mechanism and age of the prominent strike-slip tectonics in Sardinia and Corsica allows us to bear new insights on the relationships between the south European crust and Adria plate. Syntectonic Oligocene-Aquitanian deposits fill some intracratonic basins in Sardinia. They developed in correspondence with releasing bends that affect the sinistral strike-slip faults, constraining the time span during which this tectonic regime was active. Thrusts and folds involving the Mesozoic and Lower Cainozoic cover are not ubiquitous in Sardinia, they are mainly localised along deformed corridors in the NE part of the Island where deeply shortened Cainozoic conglomerates were involved in the wrench-thrust faults which, in some case, led the basement to override the Mesozoic cover. The association of these structures to restraining bends is documented, so that they are the coeval transpressive counterparts of the strike-slip basins. Confining most of the Tertiary strike-slip tectonics of Sardinia and Southern Corsica within an Oligocene-Aquitanian time interval involves the following consequences: i) no E-W extension, leading to a N-S trending rift (in presentday coordinates), was active in Sardinia and Corsica during Oligocene- Aquitanian times; ii) the so-called Sardinia Rift is an assemblage of shallow asymmetric basins, trending N150, which developed during the late Burdigalian- Langhian, i.e. contemporary to the onset of the collapse of the North Apennine and Alpine Corsica orogenic wedge and to the opening of the North Tyrrhenian Sea; iii) the Oligocene-Aquitanian strike-slip tectonics in Sardinia is consistent with the deformation of a hinterland involved in collision; this was the collision between Adria and Europe that led to the building of the North Apennines; iv) the collisional event predates the drifting of the Sardinia- Corsica crust and the opening of the Liguro-Provencal basin