Evidence for late Alpine tectonics in the Lake Garda area (northern Italy) and seismogenic implications

Abstract

We investigated the recent evolution of the Po Plain-Alps system by integrating subsurface geophysical data from the Po Plain with new stratigraphic and structural observations from the Southern Alps margin. Inversion of structural data and chronology provided by stratigraphic constraints led to the defi nition of three tectonic events since the Pliocene, namely, the intra-Zanclean, the Gelasian, and the Middle Pleistocene, driven by an axis of maximum compression formerly oriented NE (intra-Zanclean) and then to the NNW (Gelasian and Middle Pleistocene). The associated deformation has been accommodated by two sets of faults consisting of NNE-trending thrust faults, mostly represented in the western sector of Lake Garda, and NW-trending strike-slip faults, observed in the southern and eastern sectors. The interplay between these two sets of faults is interpreted to produce short (<10 km length) thrust ramps activated in left transpression, bounded by longer (30-60 km) transfer faults activated in a right-lateral strike-slip motion. Based on this structural model, we infer moderate seismicity (M w < 6) associated with the NNE-directed thrusts and stronger earthquakes (also M w > 6.5) along the NW-trending strike-slip faults. In this framework, the newly defi ned Nogara fault and the Sant'Ambrogio fault, all pertaining to the NW-trending system, are regarded as potential candidates for the seismogenic source of the January A.D. 1117 event, the most destructive earthquake in the Po Plain.

From cylindrical to non‐cylindrical foreland basin: Pliocene–Pleistocene evolution of the Po Plain–Northern Adriatic basin (Italy)

“…(A) Simplified map of the Mesozoic paleogeographic‐tectonic domain (modified after Fantoni & Franciosi, ; Turrini et al, ). Contour lines of the top Mesozoic carbonates are every 500 m (modified after Scardia et al, ; Turrini et al, ). Southern Alps and Northern Apennines thrust fronts are sketched reporting only the outermost ones.…”

“…The buried part of the belt is shaped in structural arcs (salients) with NNE-ward convexity and minor isolated structures like the Piadena Anticline, localized in the middle of the PPAF (Maesano & D the Mesozoic paleogeographic-tectonic domain (modified after Fantoni & Franciosi, 2010;Turrini et al, 2016). Contour lines of the top Mesozoic carbonates are every 500 m (modified after Scardia et al, 2015;Turrini et al, 2016). Southern Alps and Northern Apennines thrust fronts are sketched reporting only the outermost ones.…”

Early hominins in Europe: The Galerian migration hypothesis

“…8). After the regional drowning of a late Pliocene shelf associated with the northward migration of the Apeninne front (Ghielmi et al, 2010;Scardia et al, 2015), the Venice area recorded a prolonged (~1 Myr) stage of sediment starvation that ended with the onset of a massive turbiditic input in the Matuyama Chron between the highest occurrence of the nannofossil Large Gephyrocapsa (!1.25 Ma; Backman et al, 2012) and the lowest occurrence of Gephyrocapsa sp. 3 ( 0.97; Lourens et al, 2005).…”

Unconformity‐bounded stratigraphy in the Plio‐Pleistocene continental record: new insights from the Alessandria Basin (NW Italy)

“…During the Pliocene–Pleistocene transition, a tectonic pulse involved the Alps–Apennines orogenic system (e.g. Boccaletti et al ., ; Picotti and Pazzaglia, ; Ghielmi et al ., ; Scardia et al ., ). This deformation phase was accommodated by the northward overthrusting of the large thrust‐top basin onto the Po Foreland Basin along the Apennine/Padane thrust front (Biella et al ., ; Piana, ).…”