The crustal structure of the northern apennines (Central Italy): An insight by the crop03 seismic line

Abstract

In this paper, the CROP03-deep seismic reflection profile in the Northern Apennines is described and re-considered in light of new geophysical data and interpretations made available in the last five years (particularly from heat flow measurements, aeromagnetics, tomography, active stress determination and passive seismology). The crustal structure of the Northern Apennines is shown to be composed of two distinct domains. To the west is the Tyrrhenian domain and to the east is the Adriatic domain. These domains have distinctive geological and geophysical characteristics that exhibit distinct reflectivity patterns at all crustal levels. In the Tyrrhenian domain, the Upper Oligocene-Lower Miocene compressive structures are no longer recognizable, because they are dissected by subsequent extensional tectonic features. The seismic profile highlights the strong asymmetry of extensional deformation, and the upper crust is affected by a set of six major, east-dipping, low-angle normal faults. In the Adriatic domain, compressive tectonics have acted since the Middle-Miocene, and the pattern of shallow contractional structures is well preserved. The geological interpretation of the seismic data supports a thick-skinned style of deformation, where the basement is involved in the major thrust sheets. The good quality of seismic data also allows for determining the total shortening produced by the contractional structures. In the central part of the profile, at the border between the Tyrrhenian and Adriatic domains, seismic data shows the presence of an intermediate sector. The sector consists of a highly reflective window, where the refraction data indicate a local doubling of the crust for about 30 km. A scenario is presented that attempts to describe the geodynamics that drove the tectonic evolution of the Northern Apennines since the Upper Oligocene.

Fault zone architecture and deformation processes within evaporitic rocks in the upper crust

“…[6] The Northern Apennines of Italy have experienced two phases of eastward migrating deformation [Elter et al, 1975;Jolivet et al, 1998;Pauselli et al, 2006]: an early stage of Cretaceous to Quaternary shortening and thrusting was followed by a later stage of Miocene to recent postcollisional extension. Geological [Carmignani et al, 1994;Jolivet et al, 1998;Collettini and Holdsworth, 2004] and geophysical [Keller et al, 1994;Barchi et al, 1998b;Collettini et al, 2006;Chiaraluce et al, 2007] data suggest that a significant amount of extension has been accommodated by east-dipping low-angle normal faults and associated antithetic structures (Figure 1).…”

Carbonate metasomatism and CO2 lithosphere–asthenosphere degassing beneath the Western Mediterranean: An integrated model arising from petrological and geophysical data

“…The average lithospheric models proposed for the two basins by Panza and Calcagnile (1979) agree with these age estimates. Parallel zones of compression (at the front) and extension (in the back arc basins) migrated towards the east, in the same direction of the magmatism (Pauselli et al, 2006). The opening of the Tyrrhenian Sea and the counterclockwise rotation of the Italian peninsula resulted in the longitudinal stretching and fragmentation of the Apennine chain, with formation of several arc sectors separated by important transverse tectonic lines (e.g., the so-called 41° N parallel line, the Sangineto fault, the Tindari-Letojanni fault; Locardi, 1988;Turco and Zuppetta 1998;Rosenbaum et al, 2008).…”

Magmatism, mantle evolution and geodynamics at the converging plate margins of Italy

“…This was followed by opening of the Tyrrhenian Sea (c. 15 Ma to present), the counter-clockwise rotation of the Italian peninsula, and the migration of the Apennine compression front to its present position in the western AdriaticIonian area (e.g. Carminati et al 1998Carminati et al , 2010Carminati et al , 2012Doglioni et al 1998Doglioni et al , 1999Faccenna et al 2001;Cavazza & Wezel 2003;Sartori 2003;Pauselli et al 2006).…”