Geology of the Villalvernia – Varzi Line Between Scrivia and Curone valleys (NW Italy)

Abstract

The External Ligurian and Epiligurian Units in the Northern Apennines of Italy are tectonically juxtaposed with the Tertiary Piedmont Basin along the Villalvernia -Varzi Line, which represents a regional scale fault zone, E-striking. Our map, at the 1:20,000 scale, describes the tectono-stratigraphic evolution of this sector that resulted from multistage faulting along that fault zone. Four main tectonic stages are defined on the basis of the crosscutting relationships between mapped faults and stratigraphic unconformities: late Priabonian -Rupelian, Chattian -early Miocene, late Serravallian -Tortonian, and late Messinian -early Pliocene. Our results demonstrate that since the late Burdigalian, the Villalvernia -Varzi Line was sealed by the gravitational emplacement of a chaotic rock body. The deposition of the late Serravallian -early Messinian succession is controlled by NW-striking strike-slip faults that crosscut to the west the Villalvernia -Varzi Line. Extensional tectonics related to regional scale N-dipping tilting characterized the late Messinian -early Pliocene time interval.

Short-Term GIS Analysis for the Assessment of the Recent Active-Channel Planform Adjustments in a Widening, Highly Altered River: The Scrivia River, Italy

“…The geologic setting of the Scrivia basin is characterized by the tectonic units involved both in the Alps and the Northern Apennines orogeny. The outcropping geologic formations belong to the Ligurian and Epiligurian Units and to the post-orogenic sedimentary successions of the Tertiary Piedmont Basin [46][47][48][49][50]. These geologic complexes overall consist of a wide range of sedimentary rocks such as shales, marls, marly limestones, mudstones, sandstones and conglomerates.…”

“…), and it is characterized by narrow and deep-incised valleys, where competent rocks (e.g., marly limestones and conglomerates) outcrop, and by wide and gentle valleys, often characterized by alluvial fans, in case of hilly landscapes made up of soft rocks. In this section of the basin, the Plio-Quaternary tectonic evolution strongly affected both the hydrographic network (e.g., abrupt changes in direction) and the basin morphology (e.g., basin asymmetry) [48,[51][52][53][54][55]. The lower sector includes the main floodplain, where the Scrivia River becomes unconfined, and presents a series of wide fluvial terraces.…”

Pre-Alpine extensional tectonics of a peridotitelocalized oceanic core complex in the Late Jurassic, high-pressure Monviso ophiolite (Western Alps)

“…We think that inversion of extensional detachment faults into intraoceanic subduction zones under favorable geodynamic conditions provides a viable mechanism for basin collapse and closure without invoking other external driving forces in a given region. Acknowledgments Bigi et al, 1990;Bousquet et al, 2012;Fantoni et al, 2003Fantoni et al, , 2004Funicello et al, 1981;Ghibaudo et al, 2014;Ghielmi et al, 2013;Manzotti et al, 2014;Festa et al, 2015bFesta et al, , 2015cPerrone et al, 2015). (B) Tectonic cross-section across the Western Alps (modified from Lardeaux et al, 2006).…”

Geology of the Curone and Staffora Valleys (NW Italy): field constraints for the Late Cretaceous – Pliocene tectono-stratigraphic evolution of Northern Apennines

“…On the basis of a new geological mapping at the 1:5000 scale, detailed structural and stratigraphic observations, and targeted collection of biostratigraphic data, we present the 'Geological map of the Curone and Staffora Valleys (Northern Apennines, Italy)' (see Main Map) at the 1:20,000 scale. This Geological Map represents the northern prolongation of the 'Geological Map of the Villalvernia -Varzi Line between Scrivia and Curone valleys (NW Italy)' by Festa, Fioraso, Bissacca, and Petrizzo (2015).…”