Mesozoic extension controlling the Southern Alps thrust front geometry under the Po Plain, Italy: Insights from sandbox models

Ravaglia, Antonio; Seno, Silvio; Toscani, Giovanni; Fantoni, Roberto

doi:10.1016/j.jsg.2006.07.011

Cited by 33 publications

(18 citation statements)

References 31 publications

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“…The Iseo Fault corresponds to a major extensional fault of Mesozoic or Permian age, already inferred in literature from land exposures (i.e., Lake Iseo-Oglio River line [Castellarin et al, 1992], Sebino faults [Bertotti et al, 1993], Val Camonica line [Cassinis and Perotti, 1996]). East of this fault, the Southern Alps south-verging thrusts in Cenozoic terrigenous units shift to one (Fantoni et al, 2004) or two major, north-verging back thrusts (Livio et al, 2009), refl ecting a different arrangement of the deeper structures and, ultimately, a paleogeographic conditioning (see also Ravaglia et al, 2006).…”

Section: Southern Alps Structuresmentioning

confidence: 99%

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

Scardia

Festa

Monegato

et al. 2014

Geological Society of America Bulletin

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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.

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Section: Southern Alps Structuresmentioning

confidence: 99%

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

Scardia

Festa

Monegato

et al. 2014

Geological Society of America Bulletin

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“…In Middle-Late Miocene, thrusting was especially active along the frontal part of the Orobic Southern Alps (Milano belt, Laubscher 1985) and involved the OligoMiocene Gonfolite clastic wedge fed from the growing Lepontine dome to the north (Gelati et al 1991;Carrapa and Di Giulio 2001;Sciunnach and Tremolada 2004;Garzanti and Malusà 2008). The thrusts are generally sealed by the post-Messinian fill of the Po Plain (Pieri and Groppi 1981;Bersezio et al 2001;Ravaglia et al 2006). Reactivation of the frontal structures during Pliocene and Quaternary, also suggested by seismicity, is locally described (Fantoni et al 2004;Ravaglia et al 2006).…”

Section: Regional Settingmentioning

confidence: 99%

“…The thrusts are generally sealed by the post-Messinian fill of the Po Plain (Pieri and Groppi 1981;Bersezio et al 2001;Ravaglia et al 2006). Reactivation of the frontal structures during Pliocene and Quaternary, also suggested by seismicity, is locally described (Fantoni et al 2004;Ravaglia et al 2006).…”

Section: Regional Settingmentioning

confidence: 99%

Polyphase thrusting and dyke emplacement in the central Southern Alps (Northern Italy)

D’Adda

Zanchi

Bergomi

et al. 2010

Int J Earth Sci (Geol Rundsch)

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The Triassic succession of the central Southern Alps (Italy) is stacked into several units bounded by southverging low-angle thrust faults, which are related to two successive steps of crustal shortening. The thrust surfaces are cut by high-angle extensional and strike-slip faults, which controlled the emplacement of hypabissal magmatic intrusions that post-date thrusts motions. Intrusion ages based on SHRIMP U-Pb zircon dating span between 42 ± 1 and 39 ± 1 Ma, suggesting close time relationships with the earliest Adamello intrusion stages and, more in general, with the widespread calc-alkaline magmatism described in the Southern Alps. Fission-track ages of magmatic apatites are indistinguishable from U-Pb crystallization ages of zircons, suggesting that the intrusion occurred in country rocks already exhumed above the partial annealing zone of apatite (depth \ 2-4 km). These data indicate that the central Southern Alps were already structured and largely exhumed in the Middle Eocene. Although we describe minor faults affecting magmatic bodies and local reactivations of older structures, no major internal deformations have occurred in the area after the Bartonian. Neogene deformations were instead concentrated farther south, along the frontal part of the belt.

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“…These materials include wet clay (e.g., Eisenstadt andSims 2005, Withjack et al 2007), glass microbeads, aluminum microspheres (Rossi and Storti 2003), water-saturated granular materials (Graveleau et al 2011), siliceous powder (Bonnet et al 2007), hemihydrate powder (CaSO4•½H2O) (van Gent et al 2010), and a sand-mica mixture (Gomes 2013). Glass microbeads are commonly used to represent incompetent layers (e.g., mudstone, shale or a layer of high fluid pressure) between competent layers when simulating a multilayered rock package (e.g., Teixell and Koyi 2003, Panien et al 2005, 2006b, Ravaglia et al 2006 or a low-friction detachment (e.g., Turrini et al 2001, Massoli et al 2006, Malavieille 2010, Konstantinovskaya and Malavieille 2011. Glass microbeads constitute a granular material that obeys the Mohr-Coulomb criterion of failure and presents the nonlinear brittle deformation behavior of crustal TAyNARA D'ANGElO and CAROlINE J.S.…”

mentioning

confidence: 99%

Glass Microbeads in Analog Models of Thrust Wedges

D'Angelo

Gomes

2017

An. Acad. Bras. Ciênc.

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Glass microbeads are frequently used in analog physical modeling to simulate weak detachment zones but have been neglected in models of thrust wedges. Microbeads differ from quartz sand in grain shape and in low angle of internal friction. In this study, we compared the structural characteristics of microbeads and sand wedges. To obtain a better picture of their mechanical behavior, we determined the physical and frictional properties of microbeads using polarizing and scanning electron microscopy and ring-shear tests, respectively. We built shortening experiments with different basal frictions and measured the thickness, slope and length of the wedges and also the fault spacings. All the microbeads experiments revealed wedge geometries that were consistent with previous studies that have been performed with sand. However, the deformation features in the microbeads shortened over low to intermediate basal frictions were slightly different. Microbeads produced different fault geometries than sand as well as a different grain flow. In addition, they produced slip on minor faults, which was associated with distributed deformation and gave the microbeads wedges the appearance of disharmonic folds. We concluded that the glass microbeads may be used to simulate relatively competent rocks, like carbonates, which may be characterized by small-scale deformation features.

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Mesozoic extension controlling the Southern Alps thrust front geometry under the Po Plain, Italy: Insights from sandbox models

Cited by 33 publications

References 31 publications

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

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

Polyphase thrusting and dyke emplacement in the central Southern Alps (Northern Italy)

Glass Microbeads in Analog Models of Thrust Wedges

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