Tracking the Adriatic-slab travel beneath the Tethyan margin of Corsica–Sardinia by low-temperature thermochronometry

Abstract

Tracking the Adriatic-slab travel beneath the Tethyan margin of Corsica-Sardinia by low-temperature thermochronometry.

Continuity of the Alpine slab unraveled by high‐resolution P wave tomography

“…Starting from the end of the Oligocene, the Apenninic slab retreated eastward, while the Adriatic microplate still continued moving northward relative to Europe, leading to hard collision in the Alps (Figure b) [ Malusà et al ., ]. This scenario requires >200 km left‐lateral motion along lithospheric‐scale transfer zones, possibly reactivating preexisting Mesozoic structures [e.g., Malusà et al ., , ], in line with the observed slab discontinuity at depth along the complex Alps‐Apennines transition zone. The interaction between the Western Alps slab and the northward shifting Apenninic slab before the onset of Neogene slab rollback may explain the occurrence of the enigmatic north dipping high‐velocity anomaly (10 in Figure ) observed along the Alps‐Apennines transition zone.…”

“…Paleogeothermal gradients during subduction were extremely low, especially in the Alpine trench (4–6°C/km) [ Malusà et al ., ], where subduction was choked in middle‐late Eocene times by the arrival of thick European crust at the trench, and (U)HP rocks were rapidly exhumed at the surface as soon as the Adriatic Plate started moving toward the NNE (Figure b). The Adriatic slab thus obliquely subducted beneath Corsica and reached the remnants of the Alpine orogenic wedge by the end of the Oligocene [ Malusà et al ., ]. However, it is not clear whether the Adriatic slab moved farther north in the Neogene, when the Adriatic trench began retreating toward the east, leading to the opening of the Ligurian‐Provençal basin [ Jolivet and Faccenna , ; Malusà et al ., ] and controlling the counterclockwise rotation of Corsica‐Sardinia and the progressive migration of Apenninic magmatism [ Lustrino et al ., ].…”

“…The black box indicates the area of frame C. (b) Cenozoic evolution of Alpine and Apenninic subductions and coeval magmatism, simplified after Malusà et al . [, ]. In red are active subduction zones; purple arrows indicate Adria trajectories relative to Europe [from Dewey et al ., ] (numbers = age in Ma).…”

Contrasting styles of (U)HP rock exhumation along the Cenozoic Adria‐Europe plate boundary (Western Alps, Calabria, Corsica)

“…In this paper, we discuss such boundary divergence exhumation models with particular reference to the Cenozoic Adria‐Europe plate boundary in the western Mediterranean, by combining geologic evidence with plate motion and tomography constraints. We integrate petrologic, structural, and stratigraphic data from the Western Alps [ Malusà et al ., ] with available data from the Apennines and Corsica, and provide the first integrated reconstruction of the Alpine and Apenninic subduction zones within the framework of the recent palinspastic reconstructions proposed for this plate boundary area [ Malusà et al ., ]. Geologic observations are compared with predictions derived from fixed‐boundary models of synconvergence exhumation recently applied to the Western Alps [ Butler et al ., ; Jamieson and Beaumont , ].…”

“…[], encompass the first‐order geologic constraints available for the Adria‐Europe plate boundary zone, including the relative Adria‐Europe plate motion (purple arrows), the trend of the paleomargins (thick dashed lines), and the orientation of the Alpine and Apenninic trenches. The trend of the Adriatic and European passive margins is constrained by stratigraphic evidence in the South Alpine successions [ Winterer and Bosellini , ; Bertotti et al ., ; Fantoni and Franciosi , ], and by low‐temperature thermochronologic data in Corsica‐Sardinia [ Malusà et al ., ]. The paleotrench orientation during subduction in the central and Western Alps is obtained by retrodeformation in the foreland and retroforeland areas [e.g., Schönborn , ; Sinclair , ; Lickorish and Ford , ].…”