Post-collisional tectonics in the Northern Cottian Alps (Italian Western Alps)

This work integrates the results of recent geological-structural studies with new seismological data for the inner Cottian Alps to investigate the connection between faults and seismicity. The major post-metamorphic tectonic feature of this sector is represented by a N-S structure, named LisTrana Deformation Zone (LTZ). Since the Late Oligocene this structure accommodated right-lateral (Late Oligocene-Early Miocene) and subsequently normal (post-Early Miocene) displacements. In the Pleistocene, the activity of the LTZ seems to have caused the development of lacustrine basins inside the valleys that drain this sector of Western Alps. The present-day seismicity joins the northern part of the LTZ and, southwards, other minor sub-parallel structures. In transversal crosssection hypocentres highlight steep surfaces. Focal mechanisms calculated along this structure show both extensional and strike-slip solutions, mostly with one roughly N-S striking nodal plane. 3Both sub-horizontal (with NE-SW to ENE-WSW trend) and steeply dipping P axes with N-S to NW-SE sub-horizontal T axes are observed.Even if clear evidence of Quaternary tectonic activity in the area is missing, on the basis of the available seismological and geological data we propose that in the inner Northern Cottian Alps the present-day seismic activity may be connected to the LTZ, interpreted as minor sub-parallel fault strand of the Canavese Line. The kinematics of this structure is consistent with the focal mechanisms calculated in this area. Structural and seismological data indicate that LTZ is active under a bulk dextral-transtensive regime since the late Oligocene in the inner Cottian Alps, in agreement with the data published for the adjacent domain of the chain.

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“…4a), as proposed by some authors (Sue and Tricart, 2003;Delacou et al, 2008;Malusà et al 2009;Perrone et al, 2010).…”

mentioning

confidence: 63%

Seismotectonic investigations in the inner Cottian Alps (Italian Western Alps): An integrated approach

et al. 2010

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“…9). This has partitioned the different components of the bulk deformation at a regional scale, as already proposed by the recent tectonic interpretations (Sue and Tricart, 2003;Delacou et al, 2004Delacou et al, , 2008Perrone et al, 2010Perrone et al, , 2011aPerrone et al, , 2011b. The NW-SE oblique convergence between Adria and Europe, as also suggested by seismological data (Massa et al, 2006), seems to be accommodated by NE-SW thrust/transpressive faults in the Western Po Plain subsurface, and by N-S strike-slip faults along the inner border of the Cottian Alps.…”

Section: Figure 9 Herementioning

confidence: 77%

“…6, 7). By contrast, inside the Alpine chain, N-S faults are characterized by normal and subordinately dextral transtensive movements inside the chain, due to the coexistence of rotational and gravitational body forces (Perrone et al, 2010(Perrone et al, , 2011a(Perrone et al, , 2011bSue and Tricart, 2003).…”

Section: Discussionmentioning

confidence: 99%

“…Seismotectonic studies (Perrone et al, 2010(Perrone et al, , 2011a recently showed that the seismic activity of this area could be partly related to the current activity of the N-S regional faults (Col del Lis-Trana Deformation Zone) affecting the inner border of the Cottian Alps, as seismological and structural data show consistent geometry (map view and cross-section) and kinematics (Fig. 4).…”

Section: Seismotectonic Frameworkmentioning

confidence: 90%

“…The study area is affected by low-magnitude seismicity (M L < 5; Eva et al, 1997;Sue et al, 1999Sue et al, , 2007Perrone et al, 2011aPerrone et al, , 2011b. Instrumental and historical seismicity are mostly concentrated along a longitudinal band, known as the Piedmont seismic arc, roughly sub-parallel to the inner border of the Alpine chain (Fig.…”

Section: Seismotectonic Frameworkmentioning

confidence: 99%

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