Tertiary extensional tectonics in Tuscany (Northern Apennines, Italy)

Carmignani, L.; Decandia, F. A.; Fantozzi, Pier Lorenzo; Lazzarotto, A.; Liotta, Domenico; Meccheri, Marco

doi:10.1016/0040-1951(94)90061-2

Cited by 298 publications

(212 citation statements)

References 11 publications

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“…oblique to the streamlines in the material, Cobbold and Quinquis, 1980) may fold during progressive deformation in extensional detachments in the same manner as described for thrust or transcurrent ductile shear zones (see review by Williams et al, 1994). Outcrop to kilometre-scale folds have been described in extensional detachment shear zones in the Apennines (Carmignani et al, 1994) and Caledonides (Fossen and Rykkelid, 1990). Large recumbent fold structures in Fig.…”

Section: Progressive Folding In Extensional Ductile Shear Zonesmentioning

confidence: 90%

Mechanisms for folding of high-grade rocks in extensional tectonic settings

Harris

Koyi

Fossen

2002

Earth-Science Reviews

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This review of structures developed in extensional high-grade terrains, combined with results of centrifuge analogue modelling, illustrates the range of fold styles and mechanisms for folding of amphibolite to granulite facies rocks during rifting or the collapse of a thrust-thickened orogen. Several extensional fold mechanisms (such as folding within detachment shear zones) are similar to those in contractional settings. The metamorphic P -T -t path, and not fold style or mode of formation, is therefore required to determine the tectonic setting in which some folds developed. Other mechanisms such as rollover above and folding between listric normal shear zones, and folding due to isostatic adjustments during crustal thinning, are unique to extensional tectonic settings. Several mechanisms for folding during crustal extension produce structures that could easily be misinterpreted as implying regional contraction and hence lead to errors in their tectonic interpretation. It is shown that isoclinal recumbent folds refolded by open, upright folds may develop during regional extension in the deep crust. Folds with a thrust sense of asymmetry can develop due to high shear strains within an extensional detachment, or from enhanced back-rotation of layers between normal shear zones. During back-rotation folding, layers rotated into the shortening field undergo further buckle folding, and all may rotate towards orthogonality to the maximum shortening direction. This mechanism explains the presence of many transposed folds, folds with axial planar pegmatites and folds with opposite vergence in extensional terrains. Examples of folds in high-grade rocks interpreted as forming during regional extension included in this paper are from the Grenville Province of Canada, Norwegian

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Section: Progressive Folding In Extensional Ductile Shear Zonesmentioning

confidence: 90%

Mechanisms for folding of high-grade rocks in extensional tectonic settings

Harris

Koyi

Fossen

2002

Earth-Science Reviews

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“…Cetona). The drainage pattern and catchment shape are structurally controlled by the regional morphostructure of the Radicofani Graben (Baldi et al, 1994;Carmignani et al, 1994), whose major axis is oriented NW-SE. The location of the Orcia River basin southern divide, which corresponds to the boundary between the Tevere River and Ombrone River basins, is controlled by the Monte Cetona horst and the Monte Amiata and Radicofani Quaternary volcanoes.…”

Section: Landslide Susceptibility Evaluation For the Upper Orcia Valleymentioning

confidence: 99%

Landslide susceptibility assessment in the Upper Orcia Valley (Southern Tuscany, Italy) through conditional analysis: a contribution to the unbiased selection of causal factors

Vergari

Seta

Monte

et al. 2011

Nat. Hazards Earth Syst. Sci.

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Abstract. In this work the conditional multivariate analysis was applied to evaluate landslide susceptibility in the Upper Orcia River Basin (Tuscany, Italy), where widespread denudation processes and agricultural practices have a mutual impact. We introduced an unbiased procedure for causal factor selection based on some intuitive statistical indices. This procedure is aimed at detecting among different potential factors the most discriminant ones in a given study area. Moreover, this step avoids generating too small and statistically insignificant spatial units by intersecting the factor maps. Finally, a validation procedure was applied based on the partition of the landslide inventory from multi-temporal aerial photo interpretation.Although encompassing some sources of uncertainties, the applied susceptibility assessment method provided a satisfactory and unbiased prediction for the Upper Orcia Valley. The results confirmed the efficiency of the selection procedure, as an unbiased step of the landslide susceptibility evaluation. Furthermore, we achieved the purpose of presenting a conceptually simple but, at the same time, effective statistical procedure for susceptibility analysis to be used as well by decision makers in land management.

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“…The Northern Apennines tectonic pile consists of several stacked tectonic units representing different paleogeographical zones, ranging from western (internal) oceanic areas (Ligurian units) to eastern continental domains (Tuscan and Umbria-Marche units), with an intervening area of transitional crust (Subligurides units). The geological history of the Northern Apennines reflects a compressional-extensional orogenic cycle (Barchi, 2010;Brogi, 2008;Carmignani et al, 1994Carmignani et al, , 1995Elter, Giglia, Tongiorgi, & Trevisan, 1975;Liotta, Cernobori, & Nicolich, 1998), with compression dating back to the Late Cretaceous -Paleocene and following the closure of the Ligurian -Piedmont Ocean in the inner Northern Apennines (i.e. southern Tuscany).…”

Section: Geological Settingmentioning

confidence: 99%

Geological map of Pliocene-Pleistocene deposits of the Ambra and Ombrone valleys (Northern Siena Basin, Tuscany, Italy)

et al. 2013

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The study area is located across the Chianti Ridge (Tuscany, Italy), between the Upper Valdarno Basin and the Siena Basin. This area covers about 25 km 2 , forming a narrow belt oriented N -S and drained by the Ambra and Ombrone creeks, which flow northward and southward, respectively. Field mapping was carried out at 1:10,000 scale through an allostratigraphic-sedimentological approach. The study area deposits represent the infill of a SW-draining paleovalley, cut both in pre-Neogene bedrock and marine Pliocene deposits of the Siena Basin. The valley-fill succession consists of two main allounits (V1 and V2), which are conformably stacked in the northern sector of the study area, and unconformably offset in the southern sector. V1 comprises gravelly to sandy fluvial deposits, whereas V2 deposits show noticeable downvalley variability. V2 consists of poorly drained floodplain deposits in the northern sector of the paleovalley, whereas gravel and sand-bed river deposits fill its southern part. Alluvial-fan and palustrine deposits are also associated with V2 fluvial facies. A normal fault trending NW-SE is the main structural feature of the area. This fault cuts the V2 unit lowering the upstream reach and is thought to have promoted the marked facies changes observed in the fluvial deposits of unit V2.

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Tertiary extensional tectonics in Tuscany (Northern Apennines, Italy)

Cited by 298 publications

References 11 publications

Mechanisms for folding of high-grade rocks in extensional tectonic settings

Mechanisms for folding of high-grade rocks in extensional tectonic settings

Landslide susceptibility assessment in the Upper Orcia Valley (Southern Tuscany, Italy) through conditional analysis: a contribution to the unbiased selection of causal factors

Geological map of Pliocene-Pleistocene deposits of the Ambra and Ombrone valleys (Northern Siena Basin, Tuscany, Italy)

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