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Tectonic evolution of a lowangle extensional fault system

from restored crosssections in the Northern Apennines (Italy)

F. Mirabella,1 F. Brozzetti,2 A. Lupattelli,1 and M. R. Barchi1

Received 16 February 2011; revised 16 June 2011; accepted 16 August 2011; published 2 November 2011.

[1] Broad geological and geophysical documentation is available on regional extensionalsystems driven by lowangle normal faults. However, little information exists about thethreedimensional geometry and the offset distribution of such extensional structures. We

present a new set of balanced geological sections across the extensional fault systemdriven by the Altotiberina lowangle normal fault in the Northern Apennines of Italy. Wedocument this extensional system throughout a large set of surface (field surveys andgeological maps) and subsurface data (seismic reflection profiles and boreholes). Thesubsurface data allowed us to define the fault deep geometry and to obtain its structuralcontours. The fault geometry is characterized by both alongdip and alongstrikeirregularities. In crosssection, the fault displays a staircase trajectory with the shallowest

part being domeshaped and flattened to horizontal. This bending could be due to thefootwall uplift triggered by a footwall uploading greater than about 115 MPa. Thesequential restoration of five geological crosssections yields a maximum extension ofabout 10 km accumulated over approximately 3 Ma. The resulting longterm sliprate isabout 3 mm/yr, which is of the same order as the presentday extensional ratemeasured by GPS (2.53.0 mm/yr), suggesting an almost steady state extension overthe last 3 Ma. The distribution of the extension values along the fault strike is bellshaped,as expected for a continuous surface.

Citation: Mirabella, F., F. Brozzetti, A. Lupattelli, and M. R. Barchi (2011), Tectonic evolution of a lowangle extensional fault

system from restored crosssections in the Northern Apennines (Italy), Tectonics, 30, TC6002, doi:10.1029/2011TC002890.

1. Introduction

[2] In recent years regional scale extensional fault systemsdriven by lowangle normal faults (LANFs) have beenprogressively recognized and described in detail worldwide[e.g., Collettini, 2011]. The early examples, documented inthe Basin and Range [e.g., Proffett, 1977; Wernicke, 1981],were followed by many others discovered in other severelyextended regions including in New Guinea [Abers, 1991], theeastern Alps [Froitzheim et al., 1997], the Northern Apen-nines [Barchi et al., 1998b], Greece [Rietbrock et al., 1996;Zeffren et al., 2005], Tibet [Kapp et al., 2008] and Turkey[ifti and Bozkurt, 2009]. The geological evidence of suchextensional detachments consists of surface geology data[e.g., Collettini and Holdsworth, 2004; Cowan et al., 2003;Hayman et al., 2003; Smith and Faulkner, 2010], subsur-

face data [e.g., Barchi et al., 1998b; ChristieBlick et al.,

2007; Floyd et al., 2001; Lister et al., 1991], or a com-bination of surface and subsurface data sets [e.g., Boncioet al., 2000; Brozzetti et al., 2009; Collettini and Barchi,2004; Wernicke, 1985].

[3] These detachments are characterized by i) low anglesof dip (

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driving the onset and evolution of the hinterland extensionalbasins of the Northern Apennines [Pialli et al., 1998]. Thesestructures were highlighted in the late 1990s by the crustalscale CROP03 NVR profile crossing the entire ItalianPeninsula from the Tyrrhenian coast to the Adriatic coast[Pialli et al., 1998].

[8] Stratigraphical data on the syntectonic fill of the basinsshow that the age of activity of these detachments rejuvenates

eastward. The ages of thesedeposits are in fact Late Miocene

Early Pliocene along the periThyrrhenian Tuscany area,Early Late Pliocene in the central Tuscany and Late Plioceneto present in the eastern Tuscanywestern Umbria area[Argnani et al., 2003;Pascucci et al., 2006;Collettini et al.,2006].

[9] Since the Early Miocene, the internal zone of theItalian Apennines (Tyrrhenian Domain, [Pausel li et al. ,2006]) has been characterized by the eastward migrationof two coupled, NWSE striking, active deformation belts.At any time since then, a frontal contractional belt coexistedwith a subparallel extensional belt set up along the hin-terland sector [e.g.,Elter et al., 1975;Lavecchia et al., 1994;Doglioni et al., 1999;Barchi et al., 2006]. As a consequence

of their migration, all sectors of the TuscanyUmbria regionunderwent a compressional tectonic phase followed by alater extension. Some authors envisage a tectonic evolutionof the area in which the hinterland basins developed in acomplex tectonic setting characterized by compressivestresses and only successively affected by normal faulting[e.g.,Bonini and Sani, 2002;Bonini and Tanini, 2009; Saniet al., 2009].

[10] The youngest and easternmost of these LANFs arethe Val di Chiana Fault, cropping out in eastern Tuscany,and the Altotiberina Fault (ATF), cropping out near theTuscanyUmbria boundary (Figure 1).

[11] The ATF is documented in a large data set includingboth surface and subsurface geology data and geophysical

data [Brozzetti, 1995; Barchi et al., 1998b; Boncio et al.,2000; Collettini and Barchi, 2002; Brozzetti et al., 2009].The ATF is a 70 km long structure, bounding the westernflank of the high Tiber Quaternary basin and dipping 1520 ENE (Figure 1). According to Boncio et al. [2000], theATF would be a part of a wider system (Etrurian FaultSystem) extending from northern Tuscany (Pontremoli area)to southern Umbria for a total length of about 350 km.Previous estimates of the ATF maximum offset, not con-strained by restored sections, range approximately from 4 to8 km [Barchi et al., 1998b; Collettini and Barchi, 2002;Brozzetti et al., 2009].

[12] In this work, we present a set of balanced geologicalsections drawn across the ATF extensional system. This

system borders the eastern part of an extensional structuralhigh which, to the west, is bordered by the westdippingCorciano Normal Fault. The latter is the easternmost andmost important antithetic fault of the Val di Chiana LANF(Figure 1).

[13] The sections are based on an updated and coherentreconstruction of the subsurface setting of the Tiber Valleyat the boundary between Tuscany and western Umbria,resulting from the interpretation of about 40 seismicreflection profiles calibrated with six boreholes (Figure 2).The seismic data provide good resolution images of both theATF footwall and hanging wall. Some of the seismic lines

have been partially interpreted in recent years, and a numberof geological sections have been published [Mine lli andMenic hetti , 1990; Barchi et al., 1998a, 1999; Pauselliet al., 2002; Mirabella et al., 2004]. Other constraints tothe seismic interpretation are the detailed 1:50.000 and1:10.000 geological maps of the Carta Geologica dItalia[Geological Cartography Project, 2011a, 2011b, 2011c],integrated by further structural surveys we performed on

selected sites (Figure 3a).[14] The main aim of our work is to provide a quantitative

analysis of the amount of longterm extension and of itsvariations along the fault by integrating the whole surfaceand subsurface data. The goals are:

[15] 1. The sequential restoration of a set of geologicalsections across the ATF (extrapolated down to a depth ofabout 10 km) to verify the kinematic consistency of thegeological structures and to evaluate the amount of extensioncaused by ATF activity and

[16] 2. To investigate the offset variations along thestrike of the ATF and to estimate the longterm extensionalsliprates.

[17] Regarding the chronological notations in this article,

we use the new definition of the base of Quaternary at2.588 Ma (at the boundary between Pliocene and Pleisto-cene). The data of the cited authors also referred to thissubdivision, and to find the age indicated by the originalworks, the reader can refer to the cited articles.

2. Tectonic Setting

[18] The study area is located at the TuscanyUmbriaboundary (Figure 1). The contractional architecture consistsof four major tectonic units, piled up during the Miocene,including from the topmost and westernmost i) the Ligurianteleallochthon, consisting of Jurassic ophiolites covered byCretaceous pelagites and a Eocene calcareous flysch, ii) the

Mt. Falterona Nappe (Tuscan allochthon), an eastvergingimbricate thruststack made up of pelagites (Scaglia Tos-cana) and siliciclastic turbidites (Macigno formation) [Plesiet al., 2002], iii) a transitional unit (Mt. Rentella Unit)consisting of polychromic marls (Mt. Rentella formation)[Brozzetti et al., 2000] followed upward by arenites andcherts (Montagnaccia formation) [Signorini and Alimenti,1967; Barsella et al., 2009] and iv) the western Umbriaunit characterized by a mesocenozoic carbonates successionfollowed by an Early Middle Miocene foredeep turbiditesuccession (Marnoso Arenacea formation).

[19] Along the geological sections (S1 to S5 in Figure 1),three of these tectonic units (the M. Falterona Nappe, M.Rentella unit and Western Umbria unit) crop out. Their

detailed stratigraphy and stacking pattern are synthesized inthe tectonostratigraphic scheme of Figure 3b.

[20] In map view, the Falterona Nappe front shows an arcshaped trajectory described by a NS striking segment,extending from the Alpe della Luna to Mt. Murlo, and by aNNESSW striking segment, SE of the Trasimeno Lake(Figure 3a).

[21] This eastwardconvex geometry causes the outcropof the Mt. Rentella unit southeast of Mt. Murlo and buriedunder the Tuscan allochthon to the north.

[22] The Umbria unit shows contractional structures atvariable scales. At shallow levels, smallto moderate size

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Figure 1. Geological sketch of the study area showing the outcropping terrains, main thrust and normalfault systems and the trace of the balanced crosssections.


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eastverging folds (with a wavelength of some hundredmeters) and imbricate minor thrusts detaching on the marlyhorizon of the Schlier formation occur. At deeper levels, athrustandfold deformation affects the entire sedimentarysuccession, including the lowermost Triassic terms and the

upper part of the acoustic Basement [Mirabella et al., 2008a;Barchi, 2010]. In particular, west of the Tiber River, aregionalscale thrust fault (the Perugia Mountains thrust),which caused the tectonic doubling of the Burano Anhydritesand the underlying phyllites, has been drilled in the Perugia2

Figure 2. (a) Location map of the subsurface data used in this work, seismic reflection profiles and bore-holes; (b) closeup of the seismic reflection profiles organized into a three dimensional working project.

Figure 3. (a) DTM (25m resolution) of the southwestern part of the study area showing the trace of the normal faultsbelonging to the LMF, COF and ATF faultalignments (details in the text); red traces refer to ENEdipping faults,darkblue traces to SWdipping faults. The traces of the AA and BB sections (white thin lines) and of the structuralsurveysites (white stars) are also showed. The survey sites 1 to 6 are located along the LMF and the COF in poorly cemen-ted arenaceous faultbreccias with rarely preserved slickensides; survey sites 7 and 8 are located within the damage zones ofthe Mt Tezio and Mt Acuto boundary faults, the cataclasites of which allowed us to collect several striated fault planes. Thetensorial analysis of these latter data performed through the Carey and Brunier[1974] inversion method provides a welldefined extensional stressfield characterized by a subvertical s1 axis and a NESW striking subhorizontal s3 axis;(b) tectonostratigraphic scheme of the study area showing the superposition relationships occurring among the main unitsand their internal stratigraphy; (c) crosssections drawn along the AAand BBlines, based on the surface data.


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Figure 3


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and S. Donato1 wells (location in Figures 1 and 2a) [Minelliand Menichetti, 1990; Anelli et al., 1994; Barchi et al.,1998a].

[23] The timing of the compressional deformation can beinferred from the age of the foredeep deposits and of theassociated unconformities that rejuvenate eastward, consis-tently with the migration of the foredeep toward the foreland.Detailed stratigraphic reviews of the Miocene successions

[Barchi et al., 1998b;Luchetti et al., 2002;Brozzetti et al., 2002;Plesi et al., 2002] indicate that the Mt. Falterona Nappe thrustabove the internal MarnosoArenacea foredeep during theBurdigalian and that the nucleation of the western Umbriacontractional structures took place during the SerravallianTortonian interval.

[24] Since the Late Pliocene, extensional deformationseverely dissected the aforesaid tectonic pile giving rise to acomplex set of normal faults previously described in thePerugia Mts. area by Dessau [1962], Ghelardoni [1962],and Minelli and Menichetti [1990]. For this same area,Brozzetti [1995] defined a dominolike setting and sug-gested a NEdipping LANF as basal detachment. The dril-ling of the Perugia2 and S.Donato1 wells highlighted strong

extensionrelated stratigraphic elisions (up to at least 1.5 km),documenting the direct superposition of the MioceneMarnosoArenacea formation above the Triassic Anidriti diBurano formation [Martinis and Pieri, 1964; Anelli et al.,1994; Keller et al., 1994].

[25] More recent studies integrating field geology withseismic lines interpretation (CROP 03 profile and othercommercial lines) indicated that the previously describedextensional features are the surface expression of the Alto-tiberina Fault [Barchi et al., 1998b; Pialli et al., 1998;Boncio et al., 1998, 2000; Barchi et al., 2006].

[26] The activity of the ATF started during the Late Plio-cene (about 3 Ma). Numerous geological, geodetic andseismological data support the presentday fault activity. The

geological and geomorphological evidence of fault activityare concentrated on the Monterchi and Anghiari fault seg-ments, which are the ATF northeastern splays (Figure 1).These consist of a series of geological features includingbacktilted Late Pleistocene alluvial terraces and syntectonicsedimentary wedges associated with the fault segmentsimaged by shallow highresolution seismic profiles [Cattutoet al., 1995;Delle Donne et al., 2007;Brozzetti et al., 2009].

[27] Geodetic data show that the presently active SWNEhorizontal extension occurs across the high Tiber basinbetween Perugia and Citt di Castello and is in the order of2.53.0 mm/yr [DAgostino et al., 2009; Hreinsdttir andBennett, 2009].

[28] Instrumental seismological data lead some authors to

attribute the strongest earthquakes of the region to the westdipping normal faults antithetic to the ATF [Barchi et al.,1998b; Boncio and Lavecchia, 2000; Basili et al., 2008],but they also show that much of the ongoing deformation isreleased through diffuse microseismicity and aseismic slipgenerated along the ATF surface [Piccinini et al., 2003;Chiaraluce et al., 2007].

3. Surface Geology

[29] The study area (Figure 1) is crossed from NW to SEby the high Tiber basin (PerugiaSansepolcro area) and is

bordered by the Val di Chiana to the west and the UmbriaMarche calcareous Apennines to the east.

[30] From west to east, the main outcropping contractionalstructures are the outer thrusts of the Mt. Falterona and Mt.Rentella units and some internal imbrications of the UmbrianMarnoso Arenacea, i.e., the Bocca Trabaria thrust (BTT) andthe Preapennine outer thrust (PTH), with the latter borderingthe calcareous ridge to the west.

[31] Given that this is well understood, we refer to thebroad existing literature and to the brief tectonostratigraphicintroduction reported in the previous chapter for theirdescription.

[32] Regarding the extensional structures, the literaturedata are instead quite heterogeneous. Some faults of theeastern alignments have been known for more than 50 years,including the Malbe, Tezio and Acuto Mts. normal faults,[Dessau, 1956; Ghelardoni, 1962;Barnaba, 1958], but manyothers have been recognized only recently, such as the Mt.Favalto, Monterchi, Anghiari, Citt di Castello and Umber-tide faults (Figures 1 and 3a) [Cattuto et al., 1995; Barchiet al., 1998b; Boncio et al., 2000; Brozzetti et al., 2009].

[33] Since the Altotiberina Fault (ATF) was found and

described, the eastdipping structures have been generallyinterpreted as synthetic splays of the ATF whereas the westdipping faults are thought to represent antithetic subsidiarystructures.

[34] The most important and wellknown westdippingfaults are the Sansepolcro and the Gubbio faults [Boncioet al., 1998, 2000; Barchi et al., 1999; Mirabella et al.,2004, 2008b;Barchi and Ciaccio, 2009].

[35] In the high Tiber Valley (from the Perugia Mts. areato the Sansepolcro basin), recent geological surveys[Geological Cartography Project, 2011a, 2011b, 2011c]have provided a significant advancement in the identificationof normal faults. On the contrary, in the TrasimenoCortonaarea, which is characterized by outcrops of flyschtype

deposits, extensional faults were substantially unknown, andhence the amount of extension in this area was stronglyunderestimated.

[36] Therefore, we focused our fieldwork in the lattersector, which is crossed by the western part of the availableseismic lines and is, therefore, essential to strictly constraintheir interpretation and to calibrate the corresponding geo-logical sections.

[37] Figure 1 illustrates the regionalscale surface geom-etry of the outcropping contractional units and their rela-tionships with the PlioceneQuaternary normal faults. Theserelationships have been mapped by integrating literaturedata with the results of our geologicalstructural survey, asshown in Figure 3a.

[38] On the basis of our field data, we suggest that apartfrom these structures found in the northern part of the studyarea, many other normal faults which dissect the OligoceneMiocene turbidites crop out in the southwestern part, west ofthe Perugia Mts.

[39] At the surface, the recognition of faults was compli-cated by the monotony of the stratigraphic successions(Macigno, Montagnaccia and Marnoso arenacea formations)and by a dense vegetation cover. For this reason, only adetailed stratigraphic study allowed us to single out theoccurrence of the faults in many cases, and the subsequent


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field mapping of the tectonic contacts aided establishingtheir nature.

[40] In some cases, through a biostratigraphic calibrationof the successions, we were able to evaluate the amount ofthe associate displacement. Within the surveyed area, fourmain arrays of NWSE striking PlioceneQuaternary normalfaults have been recognized (Figure 3a). From West to East,they are i) the eastdipping LiscianoPian di MarteMagione

Fault set (LMF), ii) the west

dipping Corciano

PreggioFault set (COF), iii) the eastdipping boundary faults of theCitt di CastelloSansepolcro Basin and of the Perugia Mts.calcareous ridges and iv) the westdipping SansepolcroGubbio alignment. The most internal eastdipping LMFwere displaced by the westdipping COF segments.

[41] Two closely spaced eastdipping faultalignmentsconsisting of two faults form the LMF. The western align-ment comprises the Mt. Maestrino and Corgna faults (both ofthem nearly 10 km long; Figure 3a); the eastern alignment,located 2 km eastward, comprises the Lisciano Niccone andthe Pian di Marte boundary faults (Figure 3a). The faulttraces reconstructed in the field indicates for these faults adipangle ranging between 30 and 40. Mesostructural

data referred to the main LMF faults are shown in Figure 3(plots 14). Survey sites 7 and 8 are located within thedamage zones of the Mt. Tezio and Mt. Acuto boundaryfaults. These faults are characterized by welldevelopedcarbonates cataclasites, which allowed us to collect severalstriated fault planes. The tensorial analysis of these dataperformed through theCarey and Brunier [1974] inversionmethod provided a welldefined extensional stressfieldcharacterized by a subvertical s1 axisand a NESWstrikingsubhorizontal s3axis.

[42] The prevalent lithology of the Macigno outcrops,consisting of poorly cemented massive sandstones, accountsfor the very rare occurrence of kinematic indicators on thefault surfaces.

[43] South of Pian di Marte, the fault alignments of theLMF clearly stop on the COF, suggesting that it displacesthe LMF (Figure 3a).

[44] The COF consists of several adjacent NWSEstrikingextensional faults dipping toward SW, which displace thewestern side of Mt. MalbeMt. Murlo ridge. Three mainclosely spaced faultalignments have been mapped for20 km north of Corciano and a further 10 km southward.The area is locally connected by subsidiary faults and by EWstriking obliqueslip transfer faults (Figure 3a, plot 56).

[45] In the Corciano area, the surface mapping of the COFis favored by the evident tectonic contacts occurring betweenthe TriassicJurassic core of Mt. Malbe and the CretaceousTertiary succession, which gradually lower westward.

[46] The main structure, the Preggio Fault, continuesnorthward on the left side of the Niccone Valley for a further5 km.

[47] The easternmost fault of the COF crops out a fewkilometers west of the present breakaway zone of the ATF(Figure 3a). The ridge delimited by these two oppositedipping fault systems constitutes a very narrow, stronglyuplifted horst (Mt. MalbeMt. Murlo horst).

[48] On the basis of the surface geological data, a set ofgeological sections have been drawn west of the Tiber Valleyalong the trace of the available seismic lines to constrain thegeological interpretation of the seismic sections (Figure 3c).

[49] The surface sections have been elaborated with therecent 299 and 310 sheets of the Carta geologica dItalia[Geological Cartography Project, 2011b, 2011c] and inte-grated with our surveys and structural analysis as a geo-logical basis; further structural analysis was also performedwith the aim of determining the surface geometry and thenormal faults kinematics.

[50] Sections AA and BB (Figure 3c) describe a very

complex extensional structure resulting from the superpo-sition of both lowangle and highangle normal faults on thecontractional thrust stack.

[51] The sections illustrate the time and space relation-ships between the COF, the LMF and the ATF and assessthe amounts of their displacement.

[52] In particular, the following considerations arise fromtheir comparative analysis: a) the eastdipping ATF andLMF are very similar in terms of geometry and kinematics;b) the westdipping Corciano Fault postdates and offsets theLMF; c) correspondingly, the LMF might correspond to thewesternmost part of the ATF (breakaway zone), later dis-placed toward SW by the COF; d) the cumulative throwproduced by the COF decreases northward, gradually pass-

ing from more than 2.5 km in the Corciano area to 1.3 kmbetween Preggio and Mt. Murlo; a few kilometers north ofthe Niccone Valley, no surface evidence of the COF can befound; e) the displacement on the ATF also shows a gradualnorthward decrease and f) the maximum footwall exhuma-tion, highlighted by the Burano Anhydrites exhumation,occurs where the ATF and COF reach their maximum throwin correspondence of the Mt. MalbeMt. Torrazzo Triassiccore.

4. Subsurface Data

[53] The subsurface geology of the UmbriaMarcheregion was explored by the Italian Oil Company Agip

(presently Eni S.p.A) in the 1980s through the acquisition ofseismic lines and boreholes. These data have been progres-sively made available for scientific purposes. The quality ofthese seismic lines is variable because some were acquiredwith Vibroseis, and many others were acquired by explosivesproviding good images of the subsurface down to pseudodepths of about 3.54.0 s (twowaytime, hereinafter twt)corresponding to depths of 1012 km [Barchi et al., 1998a,1999;Pauselli et al., 2002; Mirabella et al., 2008b].

[54] The whole study area is covered by approximately40 seismic reflection profiles and six boreholes (data locationin Figure 2a).

[55] Since the 1980s, many works have used part of thisdata set to support their interpretation of the subsurface

geology [Bally et al., 1986; Menichetti and Minelli, 1991;Keller et al., 1994;Barchi et al., 1999;Collettini et al., 2000;Pauselli et al., 2002; Mirabella et al., 2004; Ciaccio et al.,2005;Barchi and Ciaccio, 2009].

[56] Here, we use all available geological and seismic data(both migrated and stack sections) in the area by gatheringthem into the Move(tm) package. The seismic data consist ofpaper copies of the seismic sections. By using the geo-graphical position of the seismic lines and of the boreholes,we have been able to create a threedimensional workingproject of the data (Figure 2b). This procedure allowed anaccurate and coherent interpretation of the data to be made,


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accounting for datum shifts and the crooked paths of manyseismic sections.

[57] The seismic data provide good images of the sub-surface of the study area and represent a solid basis for thebalancing of five regional geological sections that cross theATF extensional system (S1S5, traces in Figure 1).

4.1. Seismic Stratigraphy

[58] From bottom to top, the seismic reflection profilesshow five main seismostratigraphic units (Figure 4) thatrefer to i) Late PaleozoicMiddle Triassic clastic and metasedimentary rocks (acoustic basement), ii) Late Triassicevaporites (Anidriti di Burano formation), iii) lower JurassicOligocene carbonates multilayer, iv) Umbrian turbidites(Marnoso Arenacea formation and Montagnaccia formations,Early Middle Miocene) and v) OligoceneEarly MioceneFalterona Nappe (Tuscan turbidites). This correspondencewas established on the basis of previous experience in thesame region and through the calibration of deep wells,especially the Perugia2, San Donato1 and M.Civitello1 wells(Figures 5a5c) [Bally et al., 1986;Anelli et al., 1994;Barchiet al., 1998a], the locations of which are reported in Figure 2a.

[59] The analysis of the seismic facies also aided theinterpretation. The turbidites correspond to scattered, lowamplitude and scarcely continuous reflections often inter-ested by low wavelength deformations. The carbonates showmore continuous, parallel reflectors, including a prominenthighamplitude reflector generated by the Cretaceous marlyhorizon of the Marne a Fucoidi formation The evaporites aregenerally characterized by a light and transparent facies. Thetop of the acoustic basement is signed by high amplitude andobliquely stratified reflections (details in work by Mirabellaet al. [2008a]).

[60] The M.Civitello1 well, east of the Tiber Valley, crossesmost of these units from the outcropping Miocene MarnosoArenacea down to the Triassic evaporites (Figure 5c). Drill

logging data allowed us to further check the interpretedstratigraphy. We calculated a synthetic seismogram of thewell (Figure 5d), which was obtained by convolving aGaussian wavelet with the reflection coefficients sequencecalculated from the acoustic impedance log. The depthtotime conversion was achieved using the timedepth relationobtained integrating the sonic log; a vertical time shift wasalso applied to correct the offset among the wells altitude(670 m a.s.l.) and the datum plane of the seismic reflectionprofiles (500 m a.s.l.).

[61] The seismic stratigraphy provided by the syntheticseismogram corresponds well to that provided by the indus-trial seismic profiles. The most relevant reflections are relatedto sudden changes in acoustic impedance due to major

changes in lithology (Figure 5d). Thus, strong high amplitudereflections can be observed at 300 to 500 ms inside the tur-bidite succession, and the top of the carbonates correspondsto a weak lowamplitude reflector at about 500 ms. A sharpimpedance change due to a shale layer (Marne a Fucoidiformation) within carbonates rocks can be observed at about600 ms; the downward transition to an acoustically softermaterial gives rise to a strong event at 620 ms, which isrepresented by a white trough with two loweramplitudewiggles on either side of it; a similar reflection can be seenat around 750 ms, also caused by a shale layer within thecarbonates succession. Few strong reflectors can be observed

within the upper Triassic, at the carbonatesevaporitesinterface, probably related to the presence of marly levels(Rhaetavicula contorta marly limestone). Although mostlylowamplitude weak reflections come from the evaporiticsequence, some strong highamplitude events can beobserved at around 1800 ms due to the presence of salt layersfrom 4030 m to 4430 m (b.s.l.).

4.2. Seismic Evidence of the ATF[62] The eastern part of the data set (i.e., east of the Tiber

valley) depicts the subsurface geology of the ATF hangingwall, and the western part (west of the Tiber valley) depictsthe fault footwall (Figure 2a).

[63] Here, we show four seismic sections (L1, L3, L4 andL5 in Figure 2a), which are the main subsurface constraintsfor the three most significant balanced geological sectionsacross the ATF. The geological interpretation of the seismicprofiles was calibrated with surface geology data and withthe Perugia2, San Donato1 and M.Civitello1 wells.

[64] Section L1 corresponds to the Crop03 profile(Figure 6). For the part placed in the ATF hanging wall, ourinterpretation corresponds well with the one proposed by

Barchi et al. [1998a] and shows the depth geometry of thecompressional structures affecting the Northern Apenninescarbonates ridge, cropping out about 10 km SE of the traceof the section (Figure 1). We interpreted the ATF footwallby taking into account both the new surface geology dataand a set of seismic profiles that were not available when theprevious works were published. These new lines (locatedbetween Monterchi and Arezzo in Figure 1) constrain thetop of the carbonates multilayer below the outcroppingturbidites successions.

[65] Section L3 (Figure 7) is part of the seismic linesdata set acquired to drill the San Donato1 well (location inFigure 2a) and shows the subsurface geology of the ATFfootwall. The line also shows a prominent reflector corre-

sponding to a major stratigraphic elision drilled by the SanDonato1 well (172 m a.s.l., Figure 5b), where the MioceneMarnosoArenacea directly overlies the Triassic evaporites.This reflector, which we interpret as the seismic image ofthe ATF, gradually flattens westward assuming a domelikegeometry. Its western part is truncated and offset to the Westby the westdipping Corciano Fault set which abruptlylowers the top of the carbonates multilayer down to about1.2 s (twt).

[66] Section L4 (Figure 8) calibrated with the M.Civi-tello1 borehole shows one of the best images of the ATFhanging wall. The ATF is represented by the sudden cutoff of all the keyreflectors in correspondence with anEdipping set of reflections that borders the western side of

the bowlshaped fill of the Tiber Basin in the western part ofthe line [Barchi et al., 1999]. Such a shape has been inter-preted alternatively as evidence of synextensional tectonics[Barchi et al., 1998b, 1999] or of syncompressional tec-tonics [Sani et al., 2009]. We prefer the extensional modelfor the basin development because the regional geology ofthe area and geometrical models support this model [Elteret al., 1975; Martini and Sagri, 1993; Jin and Groshong,2006; Brogi and Liotta, 2008].

[67] Section L5 (Figure 9) crosses the southern part of thestudy area, near the structural culmination of Mt. Malbe,where the Triassic rocks are exposed (Figure 1). Addition-


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ally, this section crosses both the footwall and hanging wall

of the ATF to the west and to the east of the Tiber Valley,respectively. The quality of the seismic data is rather poor inthe western part of the seismic section and the only visiblereflection appears to be that of the ATF itself, calibrated withthe Perugia2 well (Figure 5b). The well and the surface dataclearly highlight the stratigraphic elision of the wholeUmbriaMarche carbonates multilayer. To the east, the sec-tion provides a very good image of the subsurface structures.In our interpretation, the ATF main detachment can be traceddown to depth of 1214 km and is characterized by a pro-nounced staircase trajectory with dips between 15 and 30.The shallower, western portion of the fault surface flattens tohorizontal, where the maximum exhumation is achieved.

[68] In the presented sections, at shallow depths (i.e.,

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Figure

5


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Figure

6.

(top)Thecrop03seismicprofile

[Barchietal.,

1998a],L1sectionlocatedinFigure2a;(bottom)geological

interpretation.


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from direct measurements performed by Agip within theboreholes in the study area and compared with other bore-holes drilled through the same lithological units in adjacentareas. The values are also consistent with literature data[Bally et al., 1986; Barchi et al., 1998a].

[71] Section S1 (Figure 10) is based on the reinterpretationof the NVR Crop03 seismic profile (Figure 6). The com-

bination of the two seismic sections L3 and L4 (Figures 7and 8) allowed us to obtain Section S3 (Figure 11), whichextends across both the ATF footwall and hanging wall.This section is calibrated with both the Mt. Civitello1 andSan Donato1 wells (Figure 5). Section S5 (Figure 12) isbased on seismic section L7 (Figure 9).

Figure 7. (top) L3 section located in Figure 2a; (bottom) geological interpretation.


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Figure

8.

(top)L4section

locatedinFigure2a;(bottom)geologicalinterpretation.


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Figure

9.

(top)L7section

locatedinFigure2a;(bottom)geologicalinterpretation.


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[72] The three geological sections give a picture of thepresentday architecture of the ATF extensional system. Thecombined effect of the COF and the ATF is responsible for

the exhumation of Late Triassic rocks (Anidriti di Buranoformation) at the ATF footwall in Sections S3 and S5.

[73] The easternmost eastdipping segment of the ATFborders the Tiber Valley basin, which is filled with up to1 km of Quaternary sediments.

[74] In crosssection view, the fault displays a compli-cated geometry composed of a lowangle detachment, pro-gressively deepening below the Northern Apennines chain,

and several high

angle synthetic and antithetic splays. Ingeneral, we assume that the age of these splays decreasesfrom West to East; the westernmost splays are the oldestfaults and have been progressively abandoned and rotated asextension migrated eastward [Brozzetti, 1995].

[75] Using the interval velocities shown in Table 1, weconverted the entire data set of seismic profiles to depth andproduced the isobath map of the ATF (Figure 13). On the

Table 1. Seismic Interval Velocities (Vp) Adopted for the Depth

Conversion of the Seismic Profiles

Seismostratigraphic UnitsInterval P WaveVelocity (km/s)

Continental deposits (Late PlioceneQuaternary) 2.0Tuscany Turbidites (Oligocene Early Miocene) 4.3Umbria Turbidites (Early Late Miocene) 4.0Carbonates multilayer (JurassicEarly Miocene) 5.6

Evaporites (Late Triassic) 6.1Acoustic Basement s.l.

a5.1

aSensu lato.

Figure 10. (top) Three steps of the restoration steps of the S1 section from presentday configuration(bottom) to about 3 Ma, before the onset of extension.


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basis of the interpreted seismic sections, we interpolated theATF reflectors to obtain a single and continuous surface.The interpolation was performed with an algorithm for themodeling of natural surfaces [Mallet, 1997], a part of theGoCad package. The depth contours (Figure 13) show that

the reconstructed ATF plane is characterized by significantgeometrical irregularities both alongdip and alongstrike.Regarding alongdip, the pronounced staircase trajectory isclearly shown by the inconstant distance of the depth con-tours that are alternatively close or distant along the fault



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dip, and alongstrike, the fault plane shows variations in theorientation from NWSE to NS.

6. Balanced Sections Across the ATF

[76] The extensional component of the deformation hasbeen sequentially restored in the S1S5 sections to obtain ameasure of the total extension, the cumulative displacementalong the ATF and the longterm slip rate accommodated bythe Altotiberina Fault.

[77] We show the sequential restoration of the most rep-resentative sections (S1, S3, and S5 traces in Figure 1).

[78] The longterm extensional deformation was restoredwith reference to the offset of the Marne a Fucoidi reflector.This choice was dictated by the fact that this reflector iswellcalibrated by the seismic data of the study area, par-ticularly in the ATF hanging wall of all the sections. In thesouthern part of the ATF footwall, the Marne a Fucoidiformation crops out (sections S3 and S5), whereas to theNorth (S1), it is buried by the Miocene turbidites.

[79] In the models of sequential restoration, the hangingwall is usually supposed to deform only by simple shear.This deformation can be represented by a shear vector,which describes the direction along which the hanging wall



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collapses on the footwall as the extension proceeds [e.g.,Gibbs, 1983; White et al., 1986; White and Yielding, 1991;Kerr and White, 1994].

[80] The restoration basically depends on the adopted

kinematic model (in our case, on the assumed shear direc-tion) and the inferred timing of the deformation.

6.1. Shear Direction

[81] Two alternative balancing procedures were performedassuming a vertical and a 70 inclined shear vector [Buddinet al., 1997]. A vertical shear direction was first consideredbecause it may represent a geometrical approximation ofdistributed brittle deformation along both synthetic andantithetic faults at the scale adopted for our crosssections[Rowan and Kligfield, 1989]. Subsequently, we applied anindirect method for calculation of the shear angle, accounting

for the orientation of minor faults in the ATF hanging wall.In fact, the occurrence of highangle SW dipping normalfaults at the hanging wall of the ATF suggests the possibilityof an inclined shear. In this second restoration procedure,

we applied an antithetic shear direction equal to 70 [Whiteet al., 1986; Rowan and Kligfield, 1989; Dula, 1991].

6.2. Timing of Activity of the ATF

[82] We started from the assumption that the ages of theoldest sediments within the extensional basins provide theage of the onset of extension and considered the availablebibliographic data in the framework of the eastward migrationof the coupled compressional and extensional tectonics.Hence we assume that 1) the Val di Chiana Fault system wasactive from the Early Pliocene to the Late Pleistocene (5 Ma)[Pascucci et al., 2007]; 2) the extension started to affect the

Figure 13. Isobath map of the ATF reflector. The thick lines are the depth contours drawn every kilo-meter, the thin lines are the depth contours every 250 m, the dotted lines are the sampled seismic linesfrom which the contours have been drawn.


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middle Tiber Valley and the Valle Umbra Basin, south ofPerugia (Figure 1), during the Late Pliocene (about 3 Ma); 3)the age of the Gubbio Fault, the main ATF antithetic fault, is1.8 Ma [Ge.Mi.Na, 1962; Menichetti and Minelli, 1991;Menichetti, 1992]; 4) the western ATF splays have beenactive since the Late Pliocene [Brozzetti, 1995]. Given theseconsiderations, the onset of extension for the restorationprocedure was set at 3 Ma.

[83] On the basis of the crosscutting relationships of oursurface data, we have established that the westernmost andoldest splays of the ATF, Late Pliocene in age, are dissectedby the highangle SWdipping faults belonging to the COFsystem. Considering that the COF is antithetic to the Val diChiana detachment fault (Figure 1), it follows that this latterstructure was still active during the Late Pliocene and thatthe ATF and Val di Chiana detachment fault were activeduring the very Late Pliocene (possibly also during part ofthe Early Pleistocene).

[84] On this basis, the normal faults in the balanced sec-tions (S1S5) were restored according to the followingchronological order: a) the Tiber Basin and the GubbioBasin boundary faults (Quaternary), b) COF system (Qua-

ternary), c) the faults displacing the eastern and the westernside of the Perugia Mts. (Late PlioceneLate Pleistocene)and d) the oldest and westernmost splays of the ATF (LatePliocene). Because a preextensional stage of activityrelated to the evolution of the Miocene foredeep is docu-mented for the Gubbio Fault and the COF [Mirabella et al.,2004; De Paola et al., 2006], only their Quaternary con-tributions to the total extension were considered in thisstudy.

[85] The displacements of the ATF resulting from therestoration along the balanced sections are summarized inTable 2, which reports the cumulative displacement, the totalvertical displacement and the total horizontal displacement.

[86] The total amount of extension ranges between 4.6

and 5.2 km for Section S1, between 6.9 and 7.6 km forSection S2, between 9 and 10 km for Section S3, between 7.7and 9 km for S4 and between 6.5 and 8.2 km for Section S5.

[87] These values are subjected to different types of error.Some of these errors are difficult to quantify, althoughothers can be confidently estimated. The unquantifiableerrors are mainly those derived from the interpretation of theseismic sections and on the selection of cutoffs for thefaults. Other sources of error stem from the adopted velocitymodel chosen for the depth conversion. An accurate eval-uation of these errors in the interpretation of some of these

seismic lines led to an estimate close to 5% [Mirabella et al.,2004]. Still other error sources can be quantified from thedifferent results obtained by applying the vertical and anti-thetic shear angles for restoration. From the resulting valuesof Table 2, this error is about 10%. In the worst case sce-nario, we estimate an uncertainty in the measures of therestoration smaller than 15%.

[88] The plot of Figure 14, reporting the obtained values,

shows that the ATF reaches a maximum value of extension(910 km), corresponding with Section S3, and progres-sively decreases toward NW and SE.

[89] Considering the onset of extension at approximately3 Ma, a maximum longterm extension in the order of3 mm/yr can be assessed along S3.

[90] The sequential restoration also points out i) thekinematic interaction between the ATF and the SWdippingnormal faults (the Gubbio Fault and COF), ii) the influenceof the staircase geometry of the ATF on the onset andevolution of the Tiber Basin at its hanging wall and iii) thepreextensional geometry of the compressional structures.

[91] The retrodeformation of the hanging wall blocks ofboth the ATF and the COF also allows us to reconstruct a

virtual preextensional minimum topographic envelope.[92] Along with the preextensional structures, we retro

deformed the presentday topography (dotted lines inFigures 1012). This line does not represent the real preextensional topography, which should also comprehend therocks eroded during the deformation phases and which wecannot easily estimate. However, this envelope may bethought as a minimum topography, representing the pres-entday topography restored to its former position. For thisreason, it considers only the rock volumes that are still presentand that have been moved by the normal fault activity. Therelative difference between this envelope and the presentdaytopography provides a minimum value of footwall unloadingdue to extension. By subtracting the minimum topography

elevation and the presentday elevation, we estimate a min-imum elision of about 4.5 km. The maximum value is reachedalong those sections, where the extensional deformation isalso maximal (S3 and S5).

[93] The rocks that have been displaced (turbidites andcarbonates) possess average densities of about 2600 kg/m3

[Pauselli and Federico, 2003]. By multiplication of thedensity, gravitational acceleration and vertical distance,these values yield a minimum unloading of about 115 MPa.

7. Conclusions

[94] Several data exist worldwide about LANFs existence

and geometry. However, no data exist about the distributionof the offset along these structures. Additionally, no exam-ples exist of sequentially restoration across a LANF. Con-sequently, there are no measures of the longterm extensionrates which can be compared with GPS data along an activelowangle detachment.

[95] In this work, we provide a new and detailed recon-struction of the subsurface geometry of the ATF low anglenormal fault. We quantify the longterm extension accom-modated by this regional structure along its strike and providea measure of the longterm extension rate accommodated bythis fault system.

Table 2. Cumulative Displacement (Offset), Total Vertical

Displacement (Throw) and Total Horizontal Displacement (Heave)

Assuming Vertical Shear and Inclined Antithetic Shear Along the

Geological CrossSections S1S5

SectionDisplacement

(km)Throw(km)

Heave at 90Shear Vector

(km)

Heave at 70Shear Vector

(km)

S1 (L1) 5.0 1.4 4.7 5.2

S2 (L2) 7.3 1.9 6.9 7.6S3 (L3+L4) 9.9 4.9 9.0 10.0S4 (L5+L6) 8.5 4.7 7.7 9.0S5 (L7) 7.9 4.5 6.5 8.3


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[96] The main conclusions of the article can be summa-rized as follows:

[97] 1. We suggest that the ATF system is characterized bya continuous fault surface (Figures 13 and 14). This fault isthe detachment for the complex pattern of both synthetic and

antithetic highangle fault segments, mapped at the surface.Some of these segments border the Quaternary Tiber Basin,thus controlling its tectonosedimentary evolution.

[98] 2. The fault geometry is characterized by a staircasetrajectory and a decrease of dip toward the surface. A domeshaped surface (Figures 7 and 11) characterizes the shal-lowest part of the fault in its central portion in the area wherethe maximum offset is achieved (Figure 14). The bending ofthe fault might have been produced by late footwall upliftdue to tectonic unloading. Though this process has also beensuggested in previous works [Brozzetti, 1995; Boncio et al.,2000], a quantitative estimate and a detailed kinematic modelwas lacking. In the present work, we provide an estimate ofthe unloading of 45 km, yielding a minimum decrease of

vertical load exceeding 100 MPa. Such a value may becompared with exhumation data in future research and usedto model this process quantitatively to verify if the unloadingpromotes the footwall uplift and fault bending.

[99] 3. The ATF offset was measured along five sections(S1S5). The overall shape depicted by these measures isbellshaped, and the offset profile decreases toward the NWand SE (Figure 14), similar to that observed worldwide forsingle fault segments (see Kim and Sanderson [2005] for areview on this topic). If these points are representative of theactual offset shape of the fault, they suggest that the fault, in

spite of its considerable length of approximately 70 km,tends to grow as a single structure.

[100] According toBoncio et al. [2000], the ATF is part ofa wider active fault system that runs NWSE along thewhole Apennines, from the GarfagnanaLunigiana region to

the Valle Umbra Basin. On the basis of our study, the ATFwould be the part of this fault system, thus driving activeextension in the Umbria region. To the NW, the extensionaldeformation could be transferred to another regional LANFas the detachment for the Casentino and Mugello Basins[Barchi, 2007; Mirabella et al., 2007]. Some other con-siderations may support this hypothesis. To the NW of theSansepolcro Basin, a regional, SWNE lineament (theArbiaMarecchia line, Figure 1) was recognized on the basisof surface geology and satellite images. This line belongs to aset of transverse lineaments (i.e., striking SWNE) that havebeen recognized by many authors in the past [seeBasili andValensise, 2001; Pascucci et al., 2007, and referencestherein]. The origin and role of these structures is not well

established, although some of them are supposed to becrustal scale discontinuities that may act as a segmentingfeature of the extensional structures.

[101] 4. The determined fault dimensions (larger than2.7*103 Km2) suggest that a maximum M = 7 earthquakecould be generated by the ATF in the case of a singlerupture propagating along the entire faultsurface [Wells andCoppersmith, 1994]. Nevertheless, this consideration con-flicts with the known seismic history of the high TiberValley, the maximum recorded events of which are the Me=6.0, 1352 Monterchi and the Me= 6.0, 1389 Bocca Serriolaearthquakes.

Figure 14. Longterm displacement profile along the ATF measured along sections S1, S2, S3, S4, S5.The plot shows the values of the vertical and horizontal offset (throw and heave). Heave was measured byusing both a 70 and 90 shear vector. The Quaternary deposits outcrop is represented by the dark grayarea. See text for the balancing procedure description.


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[102] From a seismological point of view, the behaviorof the ATF is notably not homogeneous. The northernpart (Sansepolcro, Citt di Castello) is characterized by theoccurrence of several historical events with M > 5 (11 eventssince the XIII century), whereas the southern part is almostsilent [Boschi et al., 2000]. Additionally, recent surveys haveshown that the ATF releases microseismicity [Piccinini et al.,2003; Chiaraluce et al., 2007]. This latter observation sug-

gests that the fault growth is mainly achieved by the pro-gressive rupture of small fault patches of the fault plane,causing a very large number of low magnitude events[Chiaraluce et al., 2007]. However, the record of M > 5events in its northern part leaves open the possibility ofmoderate or strong seismicity to occur.

[103] To explore this topic more completely, it would beinteresting to consider the geometric irregularities high-lighted by the ATF isobath map we elaborated. This mapshows that the fault is characterized by longitudinal bendsand irregularities alongstrike and alongdip due to attitudevariations (Figure 13). These irregularities could have animportant role in enabling the rupture propagation, and thusthey might be of interest for the evaluation of the seismo-

genic potential of the ATF and the consequent seismichazard.

[104] 5. On the basis of the longterm extensional valuesobtained through crosssection balancing (consideringactivity during the last 3 Ma), we infer a 3 mm/yr longterm extension rate. Remarkably, very similar values (2.73.0 mm/yr) have been calculated through GPS measurementsfor the presentday extensional rate in northwestern Umbria.We interpret such convergence as evidence that extensionwithin the study area occurs almost exclusively along theATF system and has been a nearly steady state processthrough time.

[105] Acknowledgments. This work was financed by DPC

INGV200810 funding. Grants to M.R. Barchi.[106] We thank Eni for permission to publish the seismic reflection

profiles. We thank M. Bonini and an anonymous reviewer for their con-structive comments.

ReferencesAbers, G. (1991), Possible seismogenic shallowdipping normal faults in

the WoodlarkDEntrecasteaux extension province, Papua New Guinea,Geology, 19, 12051208, doi:10.1130/0091-7613(1991)0192.3.CO;2.

Abers, G., C. Mutter, and J. Fang (1997), Shallow dips of normal faultsduring rapid extension: Earthquakes in the woodlarkDEntrecasteauxrift system, Papua New Guinea, J. Geophys. Res., 102, 15,30115,317,doi:10.1029/97JB00787.

Anderson, E. (1951),The Dynamics of Faulting, 2nd ed., Oliver and Boyd,Edinburgh, U. K.

Anelli, L., M. Gorza, M. Pieri, and M. Riva (1994), Subsurface well data inthe Northern Apennines (Italy), Mem. Soc. Geol. Ital., 48, 461471.

Argnani, A., G. Barbacini, M. Bernini, F. Camurri, M. Ghielmi, G. Papani,F. Rizzini, S. Rogledi, and L. Torelli (2003), Gravity tectonics driven byQuaternary uplift in the Northern Apennines: Insights from the La SpeziaReggio Emilia geotransect,Quat. Int., 101102, 1326, doi:10.1016/S1040-6182(02)00088-5.

Axen, G. J. (1999), Lowangle normal fault earthquakes and triggering,Geophys. Res. Lett., 26, 36933696, doi:10.1029/1999GL005405.

Bally, A., L. Burbi, C. Cooper, and R. Ghelardoni (1986), Balanced sec-tions and seismic reflection profiles across the central Apennines,

Mem. Soc. Geol. Ital., 35, 257310.Barchi, M. (2007), UR 2.3, inDefinizione Spaziale delle Principali Strutture

Sismogenetiche della Penisola Italiana,Progetti Sismologici di Interesseper il DPCRendicontazione C onclusiva,Progetto S2, Task 2, edited by

F. Galadini, pp. 5979, Inst. Naz Geofis. Vulcanologia, Rome, Italy.[Available at http://progettosv.rm.ingv.it/Progetti/Sismologici/S2/Task_2.pdf.]

Barchi, M. (2010), The NeogeneQuaternary evolution of the NorthernApennines: Crustal structure, style of deformation and seismicity[online], J. Virtual Explor., 36, paper 11, doi:10.3809/jvirtex.2009.00220.

Barchi, M., and M. Ciaccio (2009), Seismic images of an extensional basin,generated at the hangingwall of a lowangle normal fault: The case of theSansepolcro basin (Central Italy), Tectonophysics, 479 , 285293,

doi:10.1016/j.tecto.2009.08.024.Barchi, M., A. De Feyter, B. Magnani, G. Minelli, G. Pialli, and B. Sotera(1998a), The structural style of the UmbriaMarche fold and thrust belt,

Mem. Soc. Geol. Ital., 52, 557578.Barchi, M., A. De Feyter, M. Magnani, G. Minelli, G. Pialli, and B. Sotera

(1998b), Extensional tectonics in the Northern Apennines (Italy): Evi-dence from the CROP03 deep seismic reflection line, Mem. Soc. Geol.

Ital., 52, 528538.Barchi, M., S. Paolacci, C. Pauselli, G. Pialli, and S. Merlini (1999), Geo-

metria delle deformazioni estensionali recenti nel bacino dell Alta ValTiberina fra S.Giustino Umbro e Perugia: Evidenze geofisiche e consid-erazioni geologiche, Boll. Soc. Geol. Ital., 118, 617625.

Barchi, M., C. Pauselli, C. Chiarabba, R. Di Stefano, and C. Federico(2006), Crustal structure, tectonic volution and seismogenesis in the

Northern Apennines (Italy),Boll. Geofis. Teor. Appl., 47(3), 249270.Barnaba, P. (1958), Geologia dei Monti di Gubbio, Boll. Soc. Geol. Ital.,

77, 3970.Barsella, M., A. Boscherini, F. Botti, M. Marroni, F. Meneghini, A. Motti,

S. Palandri, and L. Pandolfi (2009), Oligocene

Miocene foredeep depos-its in the lake Trasimeno area (central Italy): Insights into the evolution ofthe Northern Apennines, Ital. J. Geosci., 128(2), 341352, doi:10.3301/IJG.2009.128.2.341.

Basili, R., and G. Valensise (2001), Seismogenic sources from geologic/geophysical data: 31fano ardizio, 32pesaro san bartolo, 33rimini off-shore north, 35rimini, 36val marecchia, in Database of PotentialSources for Earthquakes Larger Than M=5.5 in Italy, edited byL. Valensise and D. Pantosti, Ann. Geophys., 44(4), 1180.

Basili, R., G. Valensise, P. Vannoli, P. Burrato, U. Fracassi, S. Mariano,M. Tiberti, and E. Boschi (2008), The database of individual seismogenicsources (DISS), version 3: Summarizing 20 years of research on Italysearthquake geology,Tectonophysics, 453 , 2043, doi:10.1016/j.tecto.2007.04.014.

Boncio, P., and G. Lavecchia (2000), A structural model for active exten-sion in Central Italy,J. Geodyn., 29, 233244, doi:10.1016/S0264-3707(99)00050-2.

Boncio, P., F. Ponziani, F. Brozzetti, M. Barchi, G. Lavecchia, and G. Pialli(1998), Seismicity and extensional tectonics in the Northern UmbriaMarche Apennines, Mem. Soc. Geol. Ital., 52, 539555.

Boncio, P., F. Brozzetti, and G. Lavecchia (2000), Architecture and seis-motectonics of a regional lowangle normal fault zone in central taly,Tectonics, 19, 10381055, doi:10.1029/2000TC900023.

Bonini, M., and F. Sani (2002), Extension and compression in the NorthernApennines (Italy) hinterland: Evidence from the late MiocenePlioceneSienaRadicofani basin and relations with basement structures,Tectonics,21(3), 1010, doi:10.1029/2001TC900024.

Bonini, M., and C. Tanini (2009), Tectonics and Quaternary evolution ofthe Northern Apennines watershed area (upper course of Arno and Tiberrivers, Italy), Geol. J., 44(1), 229, doi:10.1002/gj.1122.

Boschi, E., E. Guidoboni, G. Ferrari, D. Mariotti, G. Valensise, andP. Gasperini (2000), Catalogue of strong Italian earthquakes from461 B.C. to 1997,Ann. Geofis.,43, 843868.

Brogi, A., and D. Liotta (2008), Highly extended terrains, lateral segmenta-tion of the substratum, and basin development: The middlelate MioceneRadicondoli basin (inner Northern Apennines, Italy), Tectonics, 2 7,TC5002, doi:10.1029/2007TC002188.

Brozzetti, F. (1995), Stile strutturale della tettonica distensiva nellUmbriaoccidentale: Lesempio dei Massicci Mesozoici Perugini, Studi Geol.Camerti, 1995(1), 105119.

Brozzetti, F., L. Luchetti, and G. Pialli (2000), La successione del MonteRentella (Umbria Occidentale); Biostratigrafia a nannofossili calcareied ipotesi per un inquadramento tettonico regionale, Boll. Soc. Geol.

Ital., 119, 407422.Brozzetti, F., P. Boncio, and G. Pialli (2002), Early middle miocene evolu-

tion of the Tuscan nappewestern Umbria foredeep system: Insights fromstratigraphy and structural analysis, Boll. Soc. Geol. Ital.,121, 329331.

Brozzetti, F., P. Boncio, G. Lavecchia, and B. Pace (2009), Present activityand seismogenic potential of a lowangle normal fault system (Citt diCastello, Italy): Constraints from surface geology, seismic reflection data


21 of 23

8/12/2019 2011 Tc 002890

22/23

and seismicity, Tectonophysics, 463 , 3146, doi:10.1016/j.tecto.2008.09.023.

Buck, W. (1993), Effect of lithospheric thickness on the formation of highand lowangle normal faults, Geology, 21, 933936, doi:10.1130/0091-7613(1993)0212.3.CO;2.

Buddin, T., S. Kane, G. Williams, and S. Egan (1997), A sensitivity anal-ysis of 3dimensional restoration techniques using vertical and inclinedshear constructions, Tectonophysics, 26 9, 3350, doi:10.1016/S0040-1951(96)00099-6.

Carey, E., and B. Brunier (1974), Analyse thorique et numrique dun

modele mcanique elementaire appliqu ltude d

une population defailles,C. R. Seances Acad. Sci., Ser. D, 279, 891894.

Cattuto, C., C. Cencetti, M. Fisauli, and L. Gregori (1995), I bacini pleis-tocenici di Anghiari e Sansepolcro nellalta valle del Tevere, Quater-nario, 8, 119128.

Chiaraluce, L., C. Chiarabba, C. Collettini, D. Piccinini, and M. Cocco(2007), Architecture and mechanics of an active lowangle normal fault:Alto Tiberina Fault, Northern Apennines, Italy, J. Geophys. Res., 112,B10310, doi:10.1029/2007JB005015.

ChristieBlick, N., M. H. Anders, S. Wills, C. D. Walker, and B. Renik(2007), Observations from the Basin and Range Province (westernUnited States) pertinent to the interpretation of regional detachmentfaults, in Imaging, Mapping and Modelling Continental Lithosphere

Extension and Breakup, edited by G. D. Karner, G. Manatschal, andL. M. Pinheiro, Geol. Soc. Spec. Publ., 282, 421441.

Ciaccio, M., M. Barchi, C. Chiarabba, F. Mirabella, and E. Stucchi (2005),Seismological, geological and geophysical constraints for the GualdoTadino Fault, UmbriaMarche Apennines (Central Italy), Tectonophy-

sics, 406, 233

247, doi:10.1016/j.tecto.2005.05.027.ifti, N., and E. Bozkurt (2009), Pattern of normal faulting in the GedizGraben, SW Turkey, Tectonophysics, 473, 234260, doi:10.1016/j.tecto.2008.05.036.

Cocco, M., P. Montone, M. R. Barchi, G. Dresen, and M. Zoback (2009),MOLE: A Multidisciplinary Observatory and Laboratory of Experimentsin central Italy, Sci. Drill., 7, 6064.

Collettini, C. (2011), The mechanical paradox of lowangle normalfaults: Current understanding and open questions, Tectonophysics,510,253268, doi:10.1016/j.tecto.2011.07.015.

Collettini, C., and M. Barchi (2002), A low angle normal fault in theUmbria region (central Italy): A mechanical model for the related micro-seismicity, Tectonophysics, 359 , 97115, doi:10.1016/S0040-1951(02)00441-9.

Collettini, C., and M. R. Barchi (2004), A comparison of structural data andseismic images for lowangle normal faults in the Northern Apennines(central Italy): Constraints on activity, in Flow Processes in Faults andShear Zones, edited by G. I. Alsop and R. E. Holdworth, Geol. Soc. Spec.

Publ., 224, 95112.Collettini, C., and R. Holdsworth (2004), Fault zone weakening and char-

acter of slip along lowangle normal faults: Insights from the ZuccaleFault, Elba, Italy, J. Geol. Soc., 1 61, 10391051, doi:10.1144/0016-764903-179.

Collettini, C., M. Barchi, C. Pauselli, C. Federico, and G. Pialli (2000), Seis-mic expression of active extensional faults in northern Umbria (centralItaly),J. Geodyn.,29, 309321, doi:10.1016/S0264-3707(99)00059-9.

Collettini, C., N. De Paola, R. Holdsworth, and M. R. Barchi (2006), Thedevelopment and behaviour of lowangle normal faults during Cenozoicasymmetric extension in the Northern Apennines, Italy, J. Struct. Geol.,28, 333352, doi:10.1016/j.jsg.2005.10.003.

Cowan, D. S., T. T. Cladouhos, and J. K. Morgan (2003), Structural geol-ogy and kinematic history of rocks formed along lowangle normalfaults, Death Valley, California, Geol. Soc. Am. Bull., 115, 12301248,doi:10.1130/B25245.1.

DAgostino, N., S. Mantenuto, E. DAnastasio, A. Avallone, G. Selvaggi,M. Barchi, C. Collettini, F. Radicioni, A. Stoppini, and F. Fastellini(2009), Contemporary crustal extension in the UmbriaMarche Apen-nines from regional CGPS networks and comparison between geodeticand seismic deformation, Tectonophysics, 476, 312, doi:10.1016/j.tecto.2008.09.033.

De Paola, N., F. Mirabella, M. Barchi, and F. Burchielli (2006), Early oro-genic normal faults and their reactivation during thrust belt evolution:The Gubbio Fault case study, UmbriaMarche Apennines (Italy),

J. Struct. Geol.,28, 19481957, doi:10.1016/j.jsg.2006.06.002.Delle Donne, D., L. Piccardi, J. Odum, W. Stephenson, and R. Williams

(2007), Highresolution shallow reflection seismic image and surfaceevidence of the upper Tiber basin active faults (Northern Apennines,Italy),Boll. Soc. Geol. Ital., 126, 323331.

Dessau, G. (1956), Contributo alla geologia del gruppo del M. Tezio (PG),Boll. Soc. Geol. Ital., 75, 2052.

Dessau, G. (1962), Geologia del M. Malbe nel quadro dei Massicci Meso-zoici del perugino, Boll. Soc. Geol. Ital., 81, 225315.

Doglioni, C., P. Harabaglia, S. Merlini, F. Mongelli, A. Peccerillo, andC. Piromallo (1999), Orogens and slabs vs. their direction of subduction,

Earth Sci. Rev.,45, 167208, doi:10.1016/S0012-8252(98)00045-2.Doser, D. (1987), The Ancash, Peru earthquake of 1946 November 10: Evi-

dence for lowangle normal faulting in the high Andes of northern Peru,Geophys. J. R. Astron. Soc., 91, 5771.

Dula, W. (1991), Geometric models of listric normal faults and rolloverfolds,AAPG Bull., 75, 16091625.

Elter, P., G. Giglia, M. Tongiorgi, and L. Trevisan (1975), Tensional andcompressional areas in the recent (Tortonian to present) evolution ofnorth Apennines, Boll. Geofis. Teor. Appl., 17, 318.

Floyd, J., J. Mutter, A. Goodliffe, and B. Taylor (2001), Evidence for faultweakness and fluid flow within an active lowangle normal fault,Nature,411, 779783, doi:10.1038/35081040.

Froitzheim, N., P. Conti, and M. van Daalen (1997), Late cretaceous,synorogenic, lowangle normal faulting along the Schlinig Fault (Swit-zerland, Italy, Austria) and its significance for the tectonics of the EasternAlps, Tectonophysics, 280, 267293, doi:10.1016/S0040-1951(97)00037-1.

Ge.Mi.Na (1962), Ligniti e Torbe dellItal ia Cen tral e, A Cura dell aGemina, 319 pp., GeoMineraria Nazionale, Rome.

Geological Cartography Project (2011a), Citt di Castello, in Carta Geolo-gica dItalia, sheet 289, scale 1:50,000, Ist. Super. per la Prot. e la Ric.Ambientale, Rome, in press.

Geological Cartography Project (2011b), Umbertide, in Carta GeologicadItali a, sheet 299, scale 1:50,000, Ist. Super. per la Prot. e la Ric.

Ambientale, Rome, in press.Geological Cartography Project (2011c), Passignano, in Carta GeologicadItali a, sheet 310, scale 1:50,000, Ist. Super. per la Prot. e la Ric.Ambientale, Rome, in press.

Ghelardoni, R. (1962), Stratigrafia e tettonica del Trias di M. Malbe pressoPerugia,Boll. Soc. Geol. Ital., 81, 6675.

Gibbs, A. (1983), Balanced crosssection construction from seismic sectionsin areasof extensional tectonics,J. Struct. Geol., 5, 153160, doi:10.1016/0191-8141(83)90040-8.

Hayman, N. W., J. R. Knott, D. S. Cowan, E. Nemser, and A. M. SarnaWojcicki (2003), Quaternary lowangle slip on detachment faults inDeath Valley, California, Geology, 31, 343346.

Hreinsdttir, S., and R. Bennett (2009), Active aseismic creep on theAlto Tiberina lowangle normal fault, Italy, Geology, 37, 683686,doi:10.1130/G30194A.1.

Jin, G., and R. H. Groshong Jr. (2006), Trishear kinematic modeling ofextensional faultpropaga tion foldin g, J. Struct. Geol., 2 8, 170183,doi:10.1016/j.jsg.2005.09.003.

Johnson, R., and K. Loy (1992), Seismic reflection evidence for seismogeniclowangle faulting in southeastern Arizona, Geology, 2 0, 597600,doi:10.1130/0091-7613(1992)0202.3.CO;2.

Kapp, P., M. Taylor, D. Stockli, and L. Ding (2008), Development of activelowangle normal faulting systems during orogenic collapse: Insightfrom Tibet, Geology, 36, 710, doi:10.1130/G24054A.1.

Keller, J., G. Minelli, and G. Pialli (1994), Anatomy of a late orogenic exten-sion: The Northern Apeninnes case, Tectonophysics, 23 8, 275294,doi:10.1016/0040-1951(94)90060-4.

Kerr, H., and N. White (1994), Application of an automated method fordetermining normal fault geometries, J. Struct. Geol., 16, 16911709,doi:10.1016/0191-8141(94)90135-X.

Kim, Y., and D. Sanderson (2005), The relationship between displacementand length of faults: A review, Earth Sci. Rev. , 68 , 317334,doi:10.1016/j.earscirev.2004.06.003.

Lavecchia, G., F. Brozzetti, M. Barchi, J. Keller, and M. Menichetti (1994),Seismotectonic zoning in eastcentral Italy deduced from the analysis ofthe Neogene to present deformations and related stress fields, Geol. Soc.

Am. Bull. , 1 06, 11071120, doi:10.1130/0016-7606(1994)1062.3.CO;2.

Lister, G., and G. Davis (1989), The origin of metamorphic core complexesand detachment faults formed during tertiary continental extension in thenorthern Colorado river region, U.S.A.,J. Struct. Geol., 11, 6594,doi:10.1016/0191-8141(89)90036-9.

Lister, G. S., M. A. Etheridge, and P. A. Symonds (1991), Detachmentmodels for the formation of passive continental margins, Tectonics, 10,10381064, doi:10.1029/90TC01007.

Luchetti, L., F. Brozzetti, C. Nini, M. Nocchi, and R. Rettori (2002),Lithostratigraphy, integrated biostratigraphy and paleoenvironmentalanalysis of the Miocene Monte Santa Maria Tiberina succession (Umbriacentral Italy), Boll. Soc. Geol. Ital., 121, 598602.

Mallet, J. (1997), Discrete modeling for natural objects, Math. Geol.,29(2),199219, doi:10.1007/BF02769628.


22 of 23

8/12/2019 2011 Tc 002890

23/23

Martini, I. P., and M. Sagri (1993), Tectonosedimentary characteristics oflate MioceneQuaternary extensional basins of the Northern Apennines,Italy,Earth Sci. Rev.,34, 197233, doi:10.1016/0012-8252(93)90034-5.

Martinis, B., and M. Pieri (1964), Alcune notizie sulla formazione evapor-itica dellItalia centrale e meridionale, Mem. Soc. Geol. Ital.,4, 649678.

Menichetti, M. (1992), Evoluzione tettonicosedimentaria della Valle diGubbio,Studi Geol. Camerti, 1992(1), 155163.

Menichetti, M., and G. Minelli (1991), Extensional tectonics and seismo-genesis in Umbria (Central Italy): The Gubbio Area, Boll. Soc. Geol.

Ital., 110, 857880.

Minelli, G., and M. Menichetti (1990), Tectonic evolution of the Perugiamassifs area (central Italy), Boll. Soc. Geol. Ital., 109, 445453.Mirabella, F., M. Ciaccio, M. Barchi, and S. Merlini (2004), The Gubbio

normal fault (central Italy): Geometry, displacement distribution and tec-tonic evolution, J. Struct. Geol., 26, 22332249, doi:10.1016/j.jsg.2004.06.009.

Mirabella, F., M. Barchi, A. Lupattelli, L. Melelli, A. Taramelli, andS. Rogledi (2007), Subsurface and surface data in the Sansepolcro, Case-ntino and Mugello basins (Northern Apennines of Italy): New constrainson the active tectonics of the area, paper presented at Geoitalia: SestoForum Italiano di Scienze della Terra, Federazione Ital. di Sci. della Terra,Rimini, Italy, 1214 Sept.

Mirabella, F., M. Barchi, A. Lupattelli, E. Stucchi, and M. Ciaccio (2008a),Insights on the seismogenic layer thickness from the upper crust structureof the UmbriaMarche Apennines (central Italy),Tectonics,27, TC1010,doi:10.1029/2007TC002134.

Mirabella, F., M. Barchi, and A. Lupattelli (2008b), Seismic reflection datain the UmbriaMarche region: Limits and capabilities to unravel the sub-

surface structure in a seismically active area, Ann. Geophys., 51(2/3),383396.Pascucci, V., A. Costantini, I. Martini, and R. Dringoli (2006), Tectono

sedimentary analysis of a complex, extensional, Neogene basin formedon thrustfaulted, Northern Apennines hinterland: Radicofani basin, Italy,Sediment. Geol., 183, 7197, doi:10.1016/j.sedgeo.2005.09.009.

Pascucci, V., I. Martini, M. Sagri, and F. Sandrelli (2007), Effects of trans-verse structural lineaments on the NeogeneQuaternary basins of Tuscany(inner Northern Apennines, Italy), in Sedimentary Processes, Environ-ments and Basins: A Tribute to Peter Friend, edited by G. Nichols,E. Williams, and C. Paola, Spec. Publ. Int. Assoc. Sedimentol. , 3 8,155182.

Pauselli, C., and C. Federico (2003), Elastic modeling of the Alto Tiberinanormal fault (central Italy): Geometry and lithological stratification influ-ences on the local stress field, Tectonophysics, 374, 99113.

Pauselli, C., R. Marchesi, and M. Barchi (2002), Seismic image of the com-pressional and extensional structures in the Gubbio area (UmbrianPreApennines),Boll. Soc. Geol. Ital., 121, 263272.

Pauselli, C., M. R. Barchi, C. Federico, B. Magnani, and G. Minelli (2006),The crustal structure of the Northern Apennines (central Italy):and insight

by the Crop03 seismi c line, Am. J. Sci., 3 06, 428450, doi:10.2475/06.2006.02.

Pialli, G., M. Barchi, and G. Minelli (Eds.) (1998), Results of the CROP 03Deep Seismic Reflection Profile, Mem. Soc. Geol. Ital., 52, 654.

Piccinini, D., et al. (2003), A microseismic study in a low seismicity area ofItaly: The Citt di Castello 20002001 experiment,Ann. Geophys.,46(6),13151324.

Plesi, G., L. Luchetti, A. Boscherini, F. Botti, F. Brozzetti, R. BucefaloPalliani, G. Daniele, A. Motti, M. Nocchi, and R. Rettori (2002), TheTuscan succession of high Tiber valley (F.289 Citt di Castello): Biostrati-graphic, petrographic and structural features, regional correlations, Boll.Soc. Geol. Ital.,121, 425436.

Proffett, J. (1977), Cenozoic geology of the Yerington district, Nevada, andimplications for the nature and origin of basin and range faulting, Geol.Soc. Am. Bull., 88, 247266, doi:10.1130/0016-7606(1977)882.0.CO;2.

Rietbrock, A., C. Tiberi, F. Sherbaum, and H. LyonCaen (1996), Seismicslip on a low angle normal fault in the Gulf of Corinth: Evidence fromhighresolution cluster analysis of microearthquakes,Geophys. Res. Lett.,23, 18171820, doi:10.1029/96GL01257.

Rigo, A., H. LyonCaen, R. Armijo, A. Deschamps, D. Hatzfeld,K. Makropoulos, P. Papadimitriou, andI. Kassaras(1996),A microseismic

study in the western gulf of Corinth (Greece): Implications for large scalenormal faulting mechanisms, Geophys.J. Int., 126, 663688, doi:10.1111/j.1365-246X.1996.tb04697.x.

Rowan, M., and R. Kligfield (1989), Cross section restoration and balanc-ing as aid to seismic interpretation in extensional terrains, AAPG Bull.,73, 955966.

Sani, F., M. Bonini, L. Piccardi, G. Vannucci, D. Delle Donne,M. Benvenuti, G. Moratti, G. Corti, D. Montanari, L. Sedda, and C. Tanini(2009) Late PlioceneQuaternary evolution of outermost hinterlandbasinsof the Northern Apennines (Italy), and their relevance to active tectonics,Tectonophysics,476, 336356, doi:10.1016/j.tecto.2008.12.012.

Signorini, R., and M. Alimenti (1967), La serie stratigrafica del M. Rentellafra il lago Trasimeno e Perugia,Geol. Rom., 6, 7594.

Smith, S. A. F., and D. R. Faulkner (2010), Laboratory measurementsof the frictional properties of the Zuccale lowangle normal fault,Elba Island, Italy, J. Geophys. Res., 115, B02407, doi:10.1029/2008JB006274.

Wells, D., and K. Coppersmith (1994), New empirical relationships among

magnitude, rupture length, rupture width, rupture area and surface dis-placement,Bull. Seismol. Soc. Am., 84(4), 9741002.Wernicke, B. (1981), Low angle normal faults in the basin and Range

Province: Nappe tectonics in an extending orogen, Nature, 291 ,645648, doi:10.1038/291645a0.

Wernicke, B. (1985), Structural discordance between neogene detachmentsand frontal sevier thrusts, central Mormon Mountains, southern Nevada,Tectonics, 4, 213246, doi:10.1029/TC004i002p00213.

Wernicke, B. (1995), Low angle normal faults and seismicity: A review,J. Geophys. Res., 100, 20,15920,174, doi:10.1029/95JB01911.

Westaway, R. (1999), The mechanical feasibility of low angle normalfaulting, Tectonophysics, 308, 407443, doi:10.1016/S0040-1951(99)00148-1.

White, N., and G. Yielding (1991), Calculating normal fault geometries atdepth: Theory and examples, in The Geometry of Normal Faults, edited

by A. Roberts, G. Yielding, and B. Freeman, Geol. Soc. Spec. Publ.,56,252260.

White, N., A. Jackson, and D. McKenzie (1986), The relationship betweenthe geometry of normal faults and that of the sedimentary layers in theirhanging walls, J. Struct. Geol., 8, 897909, doi:10.1016/0191-8141(86)90035-0.

Zeffren, S., D. Avigad, A. Heimann, and Z. Gvirtzman (2005), Age reset-ting of hanging wall rocks above a lowangle detachment fault: TinosIsland (Aegean Sea), Tectonophysics, 40 0, 125, doi:10.1016/j.tecto.2005.01.003.

M. R. Barchi, A. Lupattelli, and F. Mirabella, Dipartimento di Scienzedella Terra, Universit di Perugia, Piazza Universit 1, I06100 Perugia,Italy. ([email protected])

F. Brozzetti, Dipartimento di Scienze della Terra, Campus UniversitarioUniversit G. dAnnunzio, Chieti Scalo I66013, Italy.


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