Quaternary capable folds and seismic hazard in Lombardia (Northern Italy): the Castenedolo structure near Brescia.

We identify evidence of late Quaternary compressive tectonics in the Northern sector of the Central Po Plain through a systematic revision of the literature, new field mapping, and a new study of seismic reflection data obtained by ENI E&P. In particular, the reinterpretation of ca. 18.000 km of seismic profiles clearly shows a belt of segmented, 10 to 20 km long, fault propagation folds, controlled by the Plio-Quaternary growth of several out-of-sequence thrusts. As an example of this active structural style, in this paper we focus on a buried fold located just south of the Castenedolo Hill, a few km SE of Brescia. Although the Castenedolo anticline has long ago been described as a young compressional structure (e.g., DESIO, 1965), no detailed structural analysis of this feature has been performed until now. We calculated the uplift rates of this fold through the analysis of its syntectonic sedimentary record as imaged by the extremely high quality ENI E&P subsurface data available in the area. The evolution of this anticline was a discontinuous process characterized by several tectonic uplift pulses (with rates of ca. 0.1 mm/yr) of different duration, separated by periods of variable extent in which no fold growth occurred. The Quaternary growth history of this anticline and the presence of faulted and folded late Pleistocene to Holocene deposits at nearby sites (Ciliverghe and Monte Netto) demonstrate that the significant seismicity of this area (e.g., the December 25, 1222, Io = IX MCS Brescia earthquake, MAGRI & MOLIN, 1986; GUIDOBONI, 1986) must be related to active compressional structures within the Brescia piedmont belt. Our regional investigations show that the structural and paleoseismic setting illustrated near Castenedolo is typical of the whole Lombardia domain of the Southern Alps. This implies that the currently accepted seismotectonic model for this region, and related seismic hazard assessment, should be thoroughly and carefully re-evaluated

Geometry and timing of deformation inside a structural arc: the case of the western Emilian folds (Northern Apennine front, Italy).

Structural arcs are very common at the front of mountain belts. The complexity of their internal structures, typically non-cylindrical, is mainly due to the presence of tectonic elements (lateral ramps, strike-slip faults) oblique to the main trend of the belt. In this paper we analyse subsurface data in order to give a quantitative description of a lateral ramp affecting the Northern Apennine front inside the arcuate Emilian folds. A structural contour map of the basal thrust separating the uppermost Apennine tectonic units from the lower ones, and two regional cross-sections, were used to describe and date the interaction of tectonic and sedimentary events that led to the building of the chain. Starting from the Messinian, a deepseated thrust was responsible for the external buried structures. The tectono-sedimentary activity in the Po Plain subsurface has been going on till the beginning of Quaternary