Memorie Della Accademia Delle Scienze Di Torino

Home , Apennins, Bormida di Spigno, Castelletto Cervo, Cessole, Colma di Mombarone, Dora Riparia

Memorie della Accademia delle Scienze di Torino

Classe di Scienze Fisiche, Matematiche e Naturali

Serie V, Volume 41

ACCADEMIA DELLE S CIENZE DI T ORINO 2017 Edito con il contributo dell’Istituto di Geoscienze e Georisorse (IGG, unità di Torino) del Consiglio Nazionale delle Ricerche (CNR)

2017 ACCADEMIA DELLE S CIENZE DI T ORINO Via Accademia delle Scienze, 6 10123 Torino, Italia

Ufﬁ ci : Via Maria Vittoria, 3 10123 Torino, Italia Tel. +39-011-562.00.47; Fax +39-011-53.26.19

Tutte le memorie che appaiono nelle «Memorie dell’Accademia delle Scienze di Torino» sono disponibili in rete ad accesso aperto e sono valutate da referees anonimi attraverso un sistema di peer review . I lavori pubblicati sono classiﬁ cati in base al seguente elenco di materie: Biologia animale e dell’uomo, Biologia vegetale, Chimica, Fisica, Geoscienze, Matematica, Scienza dell’informazione, Scienza dell’ingegneria, Scienze dell’ambiente, Scienze e ingegneria dei materiali, Storia delle scienze.

L’Accademia vende direttamente le proprie pubblicazioni. Per acquistare fascicoli scrivere a: * [email protected] Per contattare la redazione rivolgersi a * [email protected]

I lettori che desiderino informarsi sulle pubblicazioni e sull’insieme delle iniziative dell’Accademia delle Scienze di Torino possono consultare il sito www.accademiadellescienze.it

ISSN: 1120-1630 ISBN: 978-88-99471-14-9 Acc. Sc. Torino Memorie Sc. Fis. 41 (2017), 3-143, 1 tab., 16 ﬁ gg. GEOSCIENZE

Geological Map of Piemonte Region at 1:250,000 scale Explanatory Notes

Memoria di F P *, L B*, R C** , A ’A**,*, G F*, A I*, P M*, S T *, G M * e M M*** presentata dal Socio corrispondente F P nell’adunanza del 10 maggio 2017 e approvata nell’adunanza del 13 dicembre 2017

Abstract. The Piemonte Geological Map is the graphical layout of a GIS Map and Geodatabase designed to represent the Alps-Apennines orogenic system from latest Cretaceous to Quaternary. The map was mostly compiled using available data (starting from historical maps of the beginning of the twentieth century to the most recent ones), which were in some cases reinterpreted in order to fi t the adopted classifi cation scheme. The Map consists of «Mapped Features» sensu GeoSciML (CGI IUGS Commission) that represent some Geologic Units, namely Lithostratigraphic units, grouped into Synthems and/or Lithotectonic Units. The hierarchy of the Lithotectonic Units depends on their belonging (in some cases debated) to one of seven palaeogeographic domains and/or genetic contexts, here used to represent the Alps-Apennines orogenic system, i.e.: the palaeo-European continental margin, the palaeo-European continental distal margin, the Liguria-Piemonte and Valais oceanic domains, the palaeo-Adriatic continental margin, the synorogenic basins and the Alpine synorogenic magmatic bodies. Furthermore, some main «Tectonic Slice Zones» have been identifi ed as major, highly tectonized, domains consisting of assemblages of Geologic Units (tectonic slices, Deformation Units) pertaining to diff erent palaeogeographic domains, with very complex stratigraphic and/ or tectonic relations between their parts. The contacts between the Lithostratigraphic and Lithotectonic Unit groups are represented in the Map by stratigraphic unconformities or tectonic contacts (Shear Displacement Structure) that are the physical result of a number of encoded Geological Events, dating back to Late Carboniferous.

* Consiglio Nazionale delle Ricerche, Istituto di Geoscienze e Georisorse (IGG), Via Valperga Caluso 35, 10125 Torino, Italy. ** Università di Torino, Dipartimento di Scienze della Terra (DST), Via Valperga Caluso 35, 10125 Torino, Italy. ***Arpa Piemonte, Via Pio VII 9, 10135 Torino, Italy. 4 Fabrizio Piana et alii

The Map Legend is essentially based on Lithostratigraphic criteria, where the Geologic Units are distinguished into polycyclic basements (mainly Variscan), cover units (mainly Mesozoic), synorogenic basins (Cenozoic) and synorogenic magmatic bodies (younger than the previously mentioned subdivisions). Once grouped into the above-mentioned main subdivisions, the Geologic Units have been listed in the Legend following their present geometric position (from the external to the internal ones or from the top to the bottom) for each distinct tectonic stack. Keywords: regional geology, Alps-Apennines orogenic system, Liguria- Piemonte oceanic domain, paleo-Adriatic continental margin, paleo-European continental margin, lithostratigraphic unit, lithotectonic unit.

Riassunto. La Carta Geologica del Piemonte è la restituzione grafi ca di un progetto GIS e del relativo geo-database pensato per rappresentare sintetica- mente il sistema orogenico Alpi-Appennino settentrionale, che caratterizza la regione piemontese e che si è sviluppato, dal Cretacico superiore all’attuale. Le unità cartografi che fondamentali della Carta sono gli «Oggetti Carto- grafi ci» («Mapped Features» sensu GeoSciML, Commissione IUGS: CGI), nello specifi co costituiti da Unità Geologiche ed in particolare da Unità Litostratigrafi che, raggruppate in Sintemi e/o in unità Litotettoniche. La gerarchia delle Unità Litotettoniche è stata defi nita in base all’appartenen- za a sette domini paleogeografi ci (o contesti genetici): il margine continentale paleo-Europeo, il margine continentale distale paleo-Europeo, i domini ocea- nici Ligure-Piemontese e Vallesano, il margine continentale paleo-Adriatico, i bacini sinorogenici, i corpi magmatici sinorogenici alpini. Inoltre, sono state identifi cate alcune «Zone a scaglie tettoniche », domini fortemente tettonizzati costituiti da insiemi di unità geologiche appartenenti a diversi domini paleogeografi ci, in complessi rapporti strutturali reciproci. I contatti tra le Unità Litostratigrafi che e le Unità Litotettoniche (o tra i loro raggruppamenti) corrispondono a superfi ci di discontinuità stratigrafi che o di contatto tettonico, che sono il risultato di eventi geologici, qui codifi cati a partire dal Carbonifero superiore. La legenda della Carta è basata essenzialmente su criteri litostratigrafi ci, con le Unità Geologiche suddivise in: i) basamenti policiclici (principalmente varisici), ii) unità di copertura sedimentaria (principalmente mesozoiche), iii) bacini sinorogenici (Cenozoici e Quaternari) e iv) corpi magmatici sinorogenici (Cenozoici). Dopo essere state raggruppate in base ai sopra citati criteri, le unità geologiche sono state rappresentate in Legenda in base alla loro posi- zione geometrica (dalla più esterna a quella più interna o da quella inferiore a quella superiore). Parole chiave: geologia regionale, dominio oceanico ligure-piemontese, margine continentale paleo-adriatico, margine continentale paleo-europeo, sistema orogenico Alpi-Appennino, unità litostratigrafi ca, unità litotettonica. Geological Map of Piemonte Region at 1:250,000 scale 5

Acknowledgments. The authors are very grateful to Giorgio V. Dal Piaz for the critical discussion on an early version of the manuscript and for the care- ful and constructive review that signiﬁ cantly improved the original version. Dario Sodero (Calgary, Alberta, Canada) is sincerely acknowledged for useful suggestions and for improving the language of the ﬁ nal text. The authors also acknowledge all people involved in the drawing of the Geological Map of Piemonte, whose work and ideas contributed to write this paper.

1. Introduction The geological map of the Piemonte Region (Italy), compiled by the Institute of Geosciences and Earth Resources of the Italian National Research Council (CNR IGG Torino) and ARPA Piemonte environmental agency, is a graphic representation of the geological setting of the region at the 1:250,000 scale, supported by the contents of a large geodatabase that can be browsed by means of WebGIS service: http://arpapiemonte.maps.arcgis.com/apps/webappviewer/index.html?id=ff f173266afa4f6fa206be53a77f6321. The Map at the 1:250,000 scale has been recently published on «Journal of Maps» (Piana et al., 2017b). The realization of the Piemonte Geological Map («GeoPiemonte Map») has been carried out by a Scientifi c Board consisting of researchers of the CNR IGG Torino, ARPA Piemonte, Department of Earth Sciences of Torino University (www.dst.unito.it) and Dip. di Ingegneria dell'Ambiente, del Territorio e delle Infrastrutture (DIATI), Politecnico di Torino. The Scientifi c Board has been assisted by a Scientifi c Support-Group consisting of qualifi ed experts in the various fi elds of Piemonte geology 1. The Map database, which is being completed, is semantically based on controlled vocabularies and a dedicated ontology (see Lombardo et al ., 2016, 2017, 2018; Piana et al., 2017a for details).

Adopted controlled vocabulary and descriptive standards The Piemonte Geological Map project adopted the IUGS GeoSciML voca- bulary2 (http://www.geosciml.org) in order to be compliant with the INSPIRE EU Directive (Data Speciﬁ cation on Geology v.2, (http://inspire.ec.europa.eu/

1 The members of the Scientifi c Support-Group are listed in a dedicated box in the Geological Map and Map Legend, which may be downloaded at http://www.tandfonline.com/doi/suppl/10 .1080/17445647.2017.1316218?scroll=top 2 IUGS CGI – GeoSciML is a data model and data transfer standard for geological data – from basic map data to complex relational geological databases. 6 Fabrizio Piana et alii documents/Data_Specifi cations/INSPIRE_DataSpecifi cation_GE_v3.0.pdf) and GeoSciML 3.2 Encoding CookBook for INSPIRE, both for Data Base and Map Legend accomplishment. The GeoSciML «Geologic Unit» Taxonomy has been chosen as a reference conceptual scheme to establish the hierarchy of the regional-to-local scale geological subdivisions, while the GeoSciML «Earth Material» and «Rock Material» Taxonomy has been used for the lithological description of the Mapped Features (Fig. 1). The geological discontinuities of both primary and secondary origin have been classifi ed following the GeoSciML «Contact» and «Geologic Structure» Taxonomy. The reconstruction of the geological evolution, onto which the subdivisions of the Map Legend were based, was displayed by the defi nition of a number of main «Geologic Event», here intended as «remarkable modifi cation of a given geological context or environment induced by a physical (tectonic, sedimentary or petrogenetic) process (or a sequence of processes)». Many of the identifi ed Geologic Events have been represented by regional-scale discontinuities preserved in the geological stratigraphic record and correlatable over wide distances and across diff erent geological domains in Piemonte.

Fig. 1. Scheme showing the relations among the Geologic Features and Geologic Concepts used for the construction of the Map Legend. Concepts and Features (represented by plain text labels) are grouped in distinct ontologies or vocabularies (represented by coloured triangles). For further details, see «WikiGeo» (https://www.di.unito.it/wikigeo/index.php?title=Pagina_principale). Geological Map of Piemonte Region at 1:250,000 scale 7

2. How to read the map The Piemonte Geological Map consists of a GIS Map and Geodatabase, which was compiled in reference to a logical model designed to represent the Alps-Apennines orogenic system. The map was mostly compiled using available data (starting from historical maps such as those of Hermann, 1937; Amstutz, 1971; Ogniben et al ., 1975; Bigi et al ., 1990 to the most recent ones), which were in some cases reinterpreted in order to fi t the adopted classifi cation scheme. The Map consists of Mapped Features («entities that provide a link between a notional feature [description package] and one spatial representation of it, or part of it, which can correspond to Exposures, Surface Traces […] ») that represent Geologic Units sensu GeoSciML («a GeologicUnit represents a body of material in the Earth whose complete and precise extent is inferred to exist. Spatial properties are only available through association with a MappedFeature»), http://www.geosciml.org/geosciml/4.0/documentation/ html/EARoot/EA1/EA3/EA1/EA123.htm. The instances of the Map Legend (represented by coloured tiles) correspond to some Lithostratigraphic Units (i.e., «a geologic unit defi ned on the basis of observable and distinctive lithologic properties or combination of lithologic properties and stratigraphic relationships», GeosciML, version 4.0), possibly grouped together into a single «Map Instance» through a correlation process: in this case they refer to the same correlation index («ID_COR» in the DataBase). The Lithostratigraphic Units are grouped into Synthems («a body of rocks bounded above and below by specifi cally designated, signifi cant discontinuities in the stratigraphic succession preferably of regional or interregional extent»), bounded by stratigraphic unconformities («a surface of erosion between rock bodies that represents a signifi cant hiatus or gap in the stratigraphic succession», International Stratigraphic Guide, http://www.stratigraphy.org/index. php/ics-stratigraphicguide). The metamorphic rocks, widespread over large part of the Piemonte Alps, have been subdivided into Lithodemic Units, (i.e., «lithostratigraphic units that lack stratifi cation» or that «do not conform to the Law of Superposition»; INSPIRE, Data Spec. on Geology, D2.8.II.4). In most cases assemblages of Lithodemic Units correspond to Metamorphic Complexes. When the Lithodemic Units were part of Metasedimentary successions, they have been grouped into informally defi ned «parasynthems», which can be correlated through the diff erent tectonic units of the Piemonte Western Alps on the basis of their primary lithologic, stratigraphic or chronostratigraphic characters (see below for further details). The lithostratigraphic units and lithodemic units have been grouped, in many cases, into Lithotectonic Units («Geologic unit defi ned on basis of structural or deformation features, mutual relations, origin or historical evolution), 8 Fabrizio Piana et alii represented in the Legend Map by several tile groups separated by «Titles». The Lithotectonic Units are bounded by Shear Displacement Structures («a generalized shear displacement structure without any commitment to the internal nature of the structure: anything from a simple, single “planar” brittle or ductile surface to a fault system with 10’s of strands of both brittle and ductile nature»). Four hierarchy orders of Titles exist in the Map (represented by distinct text styles: underlined, bold, small capital letters, italics, respectively), which correspond to relative hierarchy orders of lithotectonic units (Geol_Unit1, Geol_Unit2, Geol_Unit3, Geol_Unit4 in the DataBase). The Lithotectonic Units can be tectonic units sensu stricto, tectonometamorphic units, or tectonostratigraphic units. The hierarchy of the Lithotectonic Units is here represented by a logical scheme (Fig. 2) that shows the belonging (in some cases debated) of each Lithotectonic Unit to one of the seven palaeogeographic domains and/or genetic contexts, here used to represent the Alps-Apennines orogenic system (Fig. 3): - the palaeo-European continental margin, - the palaeo-European continental distal margin, - the Liguria-Piemonte and Valais oceanic domains, - the palaeo-Adriatic continental margin, - the synorogenic basins, - the Alpine synorogenic magmatic bodies. Furthermore, some main «Tectonic Slice Zones» have been identifi ed as major geological domains consisting of assemblages of Geologic Units (tectonic slices, Deformation Units) pertaining to diff erent palaeogeographic domains, whose stratigraphic and/or tectonic relations are so complex that their grouping in a comprehensive, highly tectonized domain, was believed to be the best solution. The contacts between the Lithotectonic Unit groups or between their component Geologic Units are represented in the Map by lines corresponding to stratigraphic unconformities (blue lines) or tectonic contacts (Shear Displacement Structure, red lines) that are the physical result of the encoded Geological Events. It must be remembered that the Map Legend is essentially based on lithostratigraphic criteria, where the Geologic Units are distinguished into polycyclic basements (mainly Variscan), cover units (mainly Mesozoic), synorogenic basins (Cenozoic) and Oligocene synorogenic magmatic bodies. Once grouped into the above-mentioned main subdivisions, the Geologic Units have been listed in the Legend following their present geometric position (from the external to the internal ones or from the top to the bottom) for each distinct tectonic stack. Geological MapofPiemonteRegionat1:250,000scale

Fig. 2. Conceptual model showing the palaeogeographic, lithostratigraphic and lithotectonic criteria used to classify the Gelogical Units according to 9 different hierarchy orders. 10 Fabrizio Piana et alii

Fig. 3. Distribution of the units derived from Mesozoic and Cenozoic palaeogeographic domains in the Piemonte region. Geological Map of Piemonte Region at 1:250,000 scale 11

Fig. 4. Tectonic sketch-map of the Piemonte region. The main Lithotectonic Units (consisting of metamorphic and/or non metamorphic units) are classified referring to the classical tectonic subdivisions of the Alpine orogenic belt, from the internal to the external zones. 12 Fabrizio Piana et alii

Fig. 5. Sketch-map showing the distribution of Quaternary deposits and Quaternary synorogenic basins in the Piemonte region. Geological Map of Piemonte Region 13 tary successions have been subdivided. Pliocene andTertiary Piemonte Basin (BTP) sedimen Fig. 6. Distribution of the synthems into which the

14 Fabrizio Piana et alii QUAT Fig. 7. Chronostratigraphic framework of the BTP and Pliocene synthems. Pliocene and BTP of the framework 7. Chronostratigraphic Fig. Geological Map of Piemonte Region at 1:250,000 scale 15 the the Maritime and Ligurian Alps have been subdivided. OU, Margin; AL, Acceglio-Longet Unit; Tertiary Piemonte BTP, Basin Fig. Fig. 8. Distribution of the synthems into which the sedimentary successions of Liguria-Piemonte Oceanic Units; Palaeo-European PP, Continental Distal succession. 16 Fabrizio Piana et alii

et al. et et al. et (2009), Mosca (2009), et al. et (1988, 1997), Falletti Falletti 1997), (1988, et al. et (2006), Larroque Larroque (2006), (1986), Biella Biella (1986), et al. et nit nit of the Gran San Bernardo Nappe System; SLZ, et al. et see inset of Fig. 4 of Fig. inset see morphic basement of the palaeo-european continental margin); margin); continental palaeo-european the of basement morphic Zone; DM, Dora-Maira; GP, Gran Paradiso; IVZ, Ivrea-Verbano Ivrea-Verbano IVZ, Paradiso; Gran GP, Dora-Maira; DM, Zone; PDZ, Provençal-Dauphinois Domain; PQ, Pliocene-Quaternary ozoic ozoic sedimentary successions of the Southalpine domain (exposed) , Rio Freddo Deformation Zone; CL, Canavese Line; Penninic PTF, (1985,1992), Cassano (1985,1992), et al. et (1996, 2004, 2017), Lardeaux Lardeaux 2017), 2004, (1996, et al. et (2010), modiﬁ ed. (2010), modiﬁ (2004), Schmid Schmid (2004), et al. et et al. et (1996), Michard Michard (1996), (2010), Schreiber (2010), Schreiber et al. et et al. et Fig. 9. Representative, regional-scale, geological cross-sections. For cross-section locations For cross-section cross-sections. geological regional-scale, 9. Representative, Fig. Legend: AC, Acceglio-Longet Unit; BTP, Tertiary Piemonte Basin; CZ, Canavese Canavese CZ, Basin; Piemonte Tertiary BTP, Unit; Acceglio-Longet AC, Legend: meta (polycyclic Bianco Monte MB, units; Ligurian metamorphic non LIG, Zone; OM, BTP Oligocene-Miocene succession; OPH, ophiolites of the Apennines; succession; PU, Units of the Liguria-Piemonte Oceanic Domain; SA, Mes and Adria crust (subsurface); SBH, SBI, SBR: Houillère Zone, Internal Zone and Ruitor U Sesia-Lanzo Domain. Valais Zone; Main VAL, tectonic structures: RFDZ Bozzo after Mainly Zone. Sestri-Voltaggio SVZ, Thrust; Frontal (1995), Roure Roure (1995), (2009), Molli (2009), Molli Geological Map of Piemonte Region at 1:250,000 scale 17

The distribution of the Lithotectonic Units is reported in the Tectonic Sketch Map of Fig. 4.

3. Geological setting

The Alps-Apennines orogenic system The geomorphological framework of the Piemonte Region is characterised by several orographic features: The Alps and Apennines mountain ranges, the hills of Monferrato, Langhe and Alto Monferrato, the large end moraine systems and fl uvio-glacial or alluvial fans at the outlet of major Alpine and Apenninic valleys, major glacial lakes in the northern part of the region, and the wide alluvial plains of Po River (Figs. 4, 5). This highly variable geomorphological framework mirrors an equally complex geologic and tectonic context, almost unique for its large variety of lithological and structural features, which induced an enormous scientifi c interest in the past decades, leading to the production of a huge quantity of multidisciplinary papers and maps. The geological setting of Piemonte consists of fragments of diff erent lithospheric sections ranging from deep lithospheric mantle rocks to oceanic basalts and relevant sedimentary covers, from plutonic and volcanic continental rocks to the overlying carbonate and siliciclastic sedimentary covers, as well as many kinds of metamorphic rocks originated in diff erent geodynamic contexts and under diff erent pressure and temperature conditions. Several Paleozoic to Cenozoic and Quaternary associations of sedimentary rocks and sediments, referred to a long-lasting sequence of magmatic, metamorphic and sedimentary events, can be recognised. The above mentioned geological complexity is the result of a continuous geodynamic process, which, since the beginning of Mesozoic, led, in Jurassic times, to the development of two continental «passive» margins: the «Palaeo-European Margin» and the «Palaeo-Adriatic Margin», and the two interposed diacronous oceanic zones: the Liguria-Piemonte Domain and the Valais Domain (Dewey & Bird, 1970; Dal Piaz et al ., 1972; 2003; Dewey et al ., 1973; Dal Piaz, 1974, 1999; Sturani, 1975; Smith, 1976; Laubscher & Bernoulli, 1977; Dal Piaz & Polino, 1989; Trümpy, 2001; Bernoulli & Jenkyns, 2009; Mohn et al., 2010; Handy et al., 2010 for a review). Since Late Cretaceous, the European and the African (Adria) continental plate margins started to converge (Le Pichon, 1968) inducing the subduction of the interposed oceanic lithosphere. This process led, since middle-late Eocene, to the collision and mutual indentation of the two plate margins. In this framework, the Alps-Apennines orogenic system originated, involving 18 Fabrizio Piana et alii both continental and oceanic crustal units that were aff ected, to very diff e- rent degrees, by metamorphic and tectonic reworking (see: Dal Piaz, 2010 for a review). An extensive development of magmatic bodies, intrusive into the orogenic belt, occurred in the early Oligocene (see: Alagna et al ., 2010 for a review). Contemporaneously, since middle Eocene, synorogenic sedimentary basins (Figs. 6, 7, 8) developed. These basins, partially overlapped and/or mu- tually interconnected, were fi lled initially with continental sediments (middle Eocene-early Oligocene), rapidly transitioning to mostly marine sediments until the Pliocene and reverting again, in the Quaternary, mostly to continental deposits. These basins recorded the collisional tectonic evolution of the Alps- Apennines orogenic system (Gelati & Gnaccolini, 1982; Clari et al., 1995; Falletti et al., 1995; Mutti et al., 1995; Piana & Polino, 1995; Dela Pierre et al., 2007; Rossi et al., 2009; Vigna et al., 2010; Ghielmi et al., 2013; Ghibaudo et al., 2014: Giraudi 2015; Irace et al., 2017) which occurred in the frame of the Europe-Adria convergence, with simultaneous counterclockwise rotation of their junction zone mostly occurring during early Miocene (Maffi one et al ., 2008). These events (see details in the next sections) led to the formation of the present Alpine chain regional setting (Figs. 4, 9), where units of pre-Alpine palaeocontinental basements and of the interposed Mesozoic oceanic units, metamorphosed at depth during the Alpine orogenesis, were exposed on the Earth’s surface after having been uplifted since middle Eocene. Discontinuous portions of the Mesozoic sedimentary covers of the continental and oceanic units, metamorphosed as well at diff erent degrees, are extensively exposed in Cottian, Maritime and Ligurian Alps and, to a lesser extent, in the Ossola region and «Lakes district» in the northern part of the Piemonte region. Portions of these sedimentary successions, which did not undergo metamorphic transformations at depth, are now part of the northern Apennines and of the Maritime and Ligurian Alps. In turn, these sediments progressively became part of the overall orogenic system, comprising most of the northern Apennines or being scattered in diff erent tectonic units of the Alps. In such a complex structural framework, dozens of major lithotectonic units (tectonometamorphic and tectonostratigraphic units) can be distinguished. The Legend of the Piemonte geological Map has, therefore, been designed with a reference to a number of major lithotectonic units. The boundaries (corrispon- ding to tectonic structures) between the units have been represented in the Map with two types of red lines (see below), depending on the hierarchy of the bounded unit. Major faults, crosscutting the lithotectonic units, have been also represented. Anyway, since the Piemonte Geological Map is not a kinematic Geological Map of Piemonte Region at 1:250,000 scale 19 map, the sense of movement of the tectonic structures was not represented3. The geometrical relations between the Geologic Units are represented in the cross sections of Fig. 9, and for further details the reader is directed to the conspicuous literature reported below in the References section.

Main Geologic Events recognized at regional scale A number of main regional-scale Geologic Events can be recognized since the beginning of the post-Variscan Late Carboniferous sedimentary cycle (the resolution of the geological record progressively increases when approaching the Recent, so that in the Neogene and Quaternary the time span between the defi ned Geologic Events signifi cantly decreases). The Geologic Events, labeled with a capital letter «F» and a progressive number from 0 to 14, here encoded, listed in Table 1 and briefl y described in this section, have provided the essential criteria to classify the Geologic Units of the Map Legend. Table 1 also reports the regional-scale discontinuities or metamorphic foliations (see below for a more detailed description) whose development can be related to each Geologic Event. The unconformities of the internal synorogenic basins are labelled with the letter «D», while those of the Alpine Foreland Basin and the pre-orogenic passive margin successions are labelled with the letter «S».

F0: Late Carboniferous to Permian beginning of continental sedimentation onto the Variscan basement due to post-Variscan transtensive tectonics and related igneous activity (Dal Piaz et al ., 1977; Cassinis et al ., 1988; Dal Piaz & Martin, 1998; Ziegler & Stampﬂ i, 2001; Gaetani, 2010). ---- onset of S0 regional unconformity

F1: Early Triassic marine transgression. Regional transgression over Permian continental deposits or polycyclic basement, largely documen- ted in the Alps (Crema et al ., 1971; De Graciansky et al ., 2011) and in the Mediterranean area (Gandin et al ., 1982). This transgression is related to the fi rst opening stage of the NeoTethys realm in the palaeo-European continent (Stampfl i et al ., 2002; Stampfl i & Borel, 2002; Schettino & Turco, 2009; Cassinis et al ., 2011) induced by thermal subsidence (Stampfl i et al ., 1998; Ziegler & Stampfl i, 2001). -- onset of S1 regional unconformity F2: Events that lead to the opening of the Alpine Tethys ocean (Late Triassic-earliest Middle Jurassic) that can be subdivided into:

3 The WebGISservice: http://arpapiemonte.maps.arcgis.com/apps/webappviewer/index.html? id=ﬀ f173266afa4f6fa206be53a77f6321 reports detailed information on individual faults and tectonic contacts of the GeoPiemonte Map. 20 Fabrizio Piana et alii

F2a: continental rifting (Rift-onset unconformity, latest Triassic-Early Jurassic). F2b: opening of the Alpine Tethys oceanic basin and beginning of the spreading phase (Dal Piaz, 1974, 1999; Lemoine, 1980; Lemoine et al ., 1986; Seton et al ., 2012; Franke, 2012) («breakup unconformity» sensu Bond et al ., 1995, earliest Middle Jurassic). -- onset of S2 regional unconformity

F3: Early Cretaceous transtensive tectonics on the southern margin of the Palaeo-European continental margin connected to the opening of the North Atlantic Ocean and the Bay of Biscay (Stampﬂ i et al ., 2002; Handy et al ., 2010, with references). -- onset of S3 regional unconformity

AT1: Alpine belt tectonic phase 1 («eo-Alpine» sensu Dal Piaz et al ., 1972): Syncronous to the Adria-Europe convergence, subduction and high- pressure (HP) metamorphism: initially in the Austroalpine Sesia-Lanzo Zone (85 Ma: Regis et al ., 2014) and later (65 Ma, Rubatto et al ., 1999), during the earlier stages of continental collision, to about 37 Ma (Bousquet et al ., 2008) in the more external parts of the orogen.

F4: Beginning of Alpine collisional tectonics , as recorded by the onset of the SW Alps foreland basin (middle Eocene) in response to continental collision; --- onset of S4 regional unconformity at the base of the Alpine foreland basin succession (middle Eocene: Sinclair, 1997; Ford et al ., 1999).

AT2: Alpine belt tectonic phase 2 ( meso-Alpine , sensu Frey et al., 1974 ): Syncollisional, HP- to greenschist-facies metamorphism, which occurred during the exhumation of the Alpine units and during the later stages of continental collision and thermal re-equilibration: from about 35 Ma (Berger & Bousquet, 2008; Bousquet et al., 2008) to about 25 Ma (i.e., after the Oligocene magmatism) in the most external parts of the orogen.

F5: Uplifting of Alpine belt (Ligurian phase I, Priabonian ), sealing the meso-Alpine tectonic structures by the commencement of sedimentation in the retroforeland «epimeso-Alpine basin» sensu Mutti et al . (1995). This event is also connected to a change in composition and provenance of the sediments in the Alpine foreland basin and corresponds to the beginning of Geological Map of Piemonte Region at 1:250,000 scale 21 the deposition of the turbidite successions (i.e., Grès d’Annot). --- onset of D0 and S5 regional unconformities

F6: End of the main exhumation phase of the Alpine HP metamorphic units (Ligurian phase II sensu Mutti et al ., 1995, earliest Oligocene), as recorded by the beginning of sedimentation in most of the retroforeland basins (BTP) (Mutti et al ., 1995; d’Atri et al ., 2016b). Development (30 Ma) of the Periadriatic magmatism (Dal Piaz et al ., 1979; Venturelli et al ., 1984; von Blanckenburg & Davies, 1995; Rosenberg, 2004) --- onset of D1 regional unconformity

F7: First «reshaping» of the Tertiary Piemonte Basin (early Burdigalian: 20 Ma) due to a main uplift event caused by the Europe-Adria ongoing collision (Dewey et al ., 1989; Rosenbaum et al ., 2002), which locally induced a marked uplift of most part of the BTP (d’Atri et al ., 2002). --- onset of D2 regional unconformity (Molli et al ., 2010; d’Atri et al ., 2016b)

AT3: Alpine belt tectonic phase 3 (neo-Alpine, sensu Frey et al ., 1974), due to the Europe-Adria persistent convergence, main uplift events since about 20 Ma up to Recent (main uplifting events correspond to F7 and F10 Geologic Events). -- re-activation or development of faults and shear zones (e.g. Sempione fault) cutting across the Alpine metamorphic nappe pile and related foliations.

F8: N-ward shifting of BTP depocentres (late Burdigalian-early Langhian: 17-15 Ma); this event (Falletti et al ., 1995) in the frame of the Europe-Adria ongoing convergence and counter-clockwise rotation of the area north of Ligurian Alps (Maﬃ one et al ., 2008): this marks the beginning of a strong but localized subsidence in the BTP (Mosca et al ., 2009; Rossi et al ., 2009) and an abrupt change in composition (from carbonate to siliciclastic) and provenance (from S-SE to SW and West) of the sediment supply (Gnaccolini, 1968; Gnaccolini & Rossi, 1994; Carrapa et al ., 2003). --- onset of D3 regional unconformity

F9 : N-ward propagation of the Apennine frontal thrust and BTP narrowing (early Tortonian: 11-10 Ma); this event represents a «continuum» with the previous F8 Geologic Event with propagation of the Apennine 22 Fabrizio Piana et alii frontal thrust onto the Padane Late Miocene Apennine foredeep, described in the Structural Model of Italy (Pieri & Groppi, 1981; Cassano et al ., 1986; Bigi et al ., 1990; Falletti et al ., 1995; Biella et al ., 1997). The combination of tectonic uplift in the southern and northern BTP domains and subsidence in the intervening central sectors was responsible for a progressive narrowing and reduction of the depocentre behind the Torino Hill-Monferrato thrust front (Dalla et al ., 1992; Rossi et al ., 2009). This basin modiﬁ cation phase paved the way for the next late Miocene to Pliocene sedimentary evolution. --- onset of D4 regional unconformity

F10 : Intra-Messinian tectonics This event is related with an important phase of structural reorganization of the lithospheric plates all along the Africa-Eurasia collisional margin (Meulenkamp & Sissingh, 2003; Duggen et al ., 2003). In NW Italy, this tectonic activity induced the northwards overthrusting of the BTP onto the Po Foreland Basin along the Padane thrust front. The N-S shortening caused an acceleration of tectonic uplift in both the northern and southern margins, favouring the dismantling of the primary evaporites and their resedimentation in the deeper central area of the basin, through large-scale mass-wasting processes (Irace et al ., 2005; Dela Pierre et al ., 2011). -- onset of D5 regional unconformity, which corresponds to the Messinian Erosional Surface (MES; sensu Roveri et al ., 2008).

F11: Late Messinian base-level minimum This event points to important modifi cations in the drainage pattern, since it corresponds to a tectonically-enhanced base level-fall related to the uplift of the basin margins (even if of minor entity than the one of the F10 Geologic Event), combined with the refi lling of the basin with brackish- to fresh-waters («Lago Mare»). After an initial tectonic rejuvenation of the relief, indicated by the D6 subtle angular unconformity and by the sharp appearance, above it, of coarse-grained fl uvial to deltaic bodies deposited into a non-marine basin, newly formed accommodation space and progressive fading of Messinian tectonic activity occurred, as indicated by the overall aggradation of fl uvio-deltaic systems (Ghibaudo et al ., 1985; Roveri et al ., 2001; Irace et al ., 2010). --- onset of D6 regional unconformity Geological Map of Piemonte Region at 1:250,000 scale 23

F12: Pliocene marine ﬂ ooding This event corresponds to the Miocene-Pliocene boundary (5.33 Ma) and marks the re-establishment of marine conditions in the Mediterranean, related to the abrupt eustatic rise at the end of the Messinian salinity crisis, which reactivated the connections with the Atlantic Ocean (Iaccarino et al ., 1999; Gennari et al ., 2008; Violanti, 2012; Ghielmi et al ., 2010, 2013). --- onset of D7 regional unconformity

F13: Intra-Zanclean tectonics It is a compressional event that induced the overthrusting of the Pliocene southern Basin onto the coeval Pliocene Padane Basin with consequent uplift and erosion of the southern margin of the Pliocene southern basin (Bertotti et al ., 2006; Vigna et al ., 2010) and of the northwestern margin of the Pliocene Padane Basin (Ghielmi et al ., 2010, 2013). This event generated basin-scale regression (Vigna et al ., 2010; Irace et al ., 2010; Ghielmi et al ., 2010, 2013) of deep- to shallow-marine depositional systems, which became progressively transitional and ﬁ nally continental. --- onset of D8 regional unconformity

F14: Gelasian tectonic event: fragmentation of the Pliocene basin Compressional event of the Alps-Apennines orogenic system (e.g., Boccaletti et al ., 1992; Picotti & Pazzaglia, 2008; Ghielmi et al ., 2010, 2013; Scardia et al ., 2015), which led to the onset of the Quaternary continental sedimentation. This deformation phase was accommodated by further northward overthrusting of the large southern Piemonte thrust-top basin (see Pliocene succession) onto the Po Foreland Basin along the north-verging Padane thrust front (Delacou et al ., 2004; Michetti et al ., 2012; Perrone et al ., 2013; Irace et al ., 2017). The N-S shortening caused uplift of the basin margins (Langhe, Asti and Torino Hill-Monferrato region), their active subaerial erosion (Carraro, 1996; Vigna et al ., 2010; Irace et al ., 2010; 2017) and a sharp increase in coarse-grained ﬂ uvial sedimentation in the intervening subsiding sectors. This uplift reduced the lateral continuity of the Pliocene basin and led to the establishment of three diﬀ erentiated depocentres: The Savigliano and Alessandria basins to the south, and the Western Po Basin to the north. --- onset of D9 regional unconformity 24 Fabrizio Piana et alii

Regional Geologic Age of Geological Source Unconformity Event disconti- Domain or Schistosity nuity (in Piemonte) S0 - Post-Variscan F0- Post- Late Briançonnais, Dal Piaz & Martin, continental Variscan Carboniferous Dauphinois, 1998; Muttoni et deposition transtensive - Permian Southern Alps al ., 2009; tectonics, Gaetani, 2010 igneous underplating, thermal perturbation and magmatic activity S1 - Marine F1- Extensional Early Triassic Briançonnais, Cassinis et al., transgression tectonics on Dauphinois, 2011; Stampfl i et Laurasia due Southern Alps al ., 2002; Stampfl i to NeoTethys & Borel., 2002. opening S2 - Tethyan F2a- latest Triassic Briançonnais, Lemoine et al., rift-onset uncon- Continental - Dauphinois, 1986; formity + breakup rifting Middle Southern Alps Masini et al., 2013 unconformity F2b- opening Jurassic Austroalpine of the oceanic Alpine Tethys S3 - Transtensive F3- Early Briançonnais, Dercourt et al., tectonics on the Transtensive Cretaceous Dauphinois, 2000; southern margin of tectonics, ope- Pre- Lagabrielle et al., Eurasia ning of North Piemontese, 2010 Atlantic ocean Valais basin MS1 HP schistosity AT1- Alpine latest Alps- Dal Piaz et al. subduction Cretaceous- Apennines 1972, 2003 middle System Eocene S4 F4- Beginning middle Alpine Sinclair, 1997; of collisional Eocene Foreland Basin Ford et al., 1999; Alpine tecto- Frey et al., 1974 nics and related metamorphism MS2 AT2- Start of latest Eocene Alps- Frey et al., 1974; greenschist-facies exhumation of - earliest Apennines Dal Piaz & Gosso, foliation Alps HP units Oligocene System 1994 and subducted slab break off

The table continues in the next page. Geological Map of Piemonte Region at 1:250,000 scale 25

S5/DO F5- Alpine Priabonian Alpine Mutti et al., 1995 belt exhuma- Foreland tion - Ligurian Basin, BTP phase I (epi-mesoalpine basin) D1 F6- Ligurian early Rupelian BTP Mutti et al., 1995; phase II Dela Pierre et al., 2003b; d’Atri et al., 2016b D2 F7- BTP resha- early BTP Dela Pierre et al., ping - W Alps Burdigalian 2003b; uplifting d’Atri et al., 2016b Development of AT3- Internal post-Burdiga- Alps- post-metamorphic W Alps lian Apennines foliations uplifting System D3 F8- N-ward late BTP Dela Pierre et al., shifting Burdigalian- 2003b; of BTP early d’Atri et al., 2016b depocenters Langhian D4 F9- N-ward early BTP Falletti et al., propagation of Tortonian 1995; Rossi et al., S-Padane thrust 2009 fronts and BTP narrowing D5 (Messinian F10- Messinian BTP Irace et al., 2005; erosional surface, Intra-Messinian Dela Pierre et al., MES) tectonics 2011 D6 F11- Late late Messinian BTP Irace et al., 2005; Messinian base- Dela Pierre et al., level minimum 2011 D7 F12- early Pliocene Violanti, 2012; Pliocene marine Zanclean basins Ghielmi et al., ﬂ ooding 2013 D8 F13- late Zanclean Pliocene Vigna et al., 2010; Intra Zanclean basins Ghielmi et al., tectonics 2013 D9 F14- Gelasian Gelasian Quaternary Vigna et al., 2010; tectonics: basins Ghielmi et al., Pliocene Basin 2013; fragmentation Irace et al., 2017

Table 1. List of the encoded Geologic Events back to late Carboniferous, which the Geologic Units and Geologic Structures of the Map have been referred to, in order to make correlations at regional scale.

26 Fabrizio Piana et alii

4. Criteria for geological classiﬁ cation and map representation

Fundamental geological criteria The classiﬁ cation criteria used in the Map are based on the main physiographic and palaeogeographic domains where the geologic units originally formed, i.e.:

- the European continental margin, - the European continental distal margin, - the Liguria-Piemonte and Valais oceanic domains, - the Adriatic continental margin, - the synorogenic basins, - the Alpine synorogenic magmatic bodies.

Furthermore, some main «Tectonic Slice Zones » have been identifi ed as major tectonic composite domains consisting of assemblages of Deformation Units. These are made up of Geological Units pertaining to diff erent palaeogeographic domains, whose mutual stratigraphic and/or tectonic relations are so complex that their grouping in a distinct tectonic domain has been considered as the best solution. It is worth to point out that the «European margin» concept is used here in the meaning of Handy et al . (2010) and Mohn et al . (2010), where the Briançonnais domain can be viewed as an isolated fragment (microcontinent) of the European continental margin placed between the Valais and the Liguria- Piemonte oceanic domains (for the northern part of Piemonte) and a portion of the hyper-extended European continental margin (for the south-western part). In regards to the Adriatic margin, we used this concept referring solely to the continental margin of the «Adriatic plate sensu stricto», i.e. the northern part of the Apulian plate s.l., as in Stampfl i et al. (1998). All the Mapped Units are considered here as parts of the «Alps-Apennines orogenic system», which is currently still evolving as a whole system. With this term (in which the words «Alps» and «Apennines» refer solely to their original geographic meaning) we intended to include all the Geologic Units involved in the orogenetic processes that aff ected, since the Late Cretaceous, the palaeo-European and the palaeo-Adriatic margins, as well as the Liguria- Piemonte and Valais oceanic domains. The orogenic system includes also the and the Cenozoic synorogenic sedimentary basins, which are now incorporated in the orogenic belt. At the western Mediterranean scale, the Alps and Apennines show distinct geomorphological, geological and geophysical characters (Carminati & Doglioni, 2012). In Piemonte, the region where these two mountain ranges Geological Map of Piemonte Region at 1:250,000 scale 27 join, the distinction (and the relative «boundary») between these two corresponding orogens could be controversial (Elter et al ., 1966; Gelati & Pasquaré, 1970; Elter & Pertusati, 1973; Schumacher & Laubscher, 1996) or in some cases meaningless, since they grounded on diff erent criteria such as palaeogeography, crustal depth at which the geological units were metamorphosed, tectonic vergence, or the age of deformation. For these reasons, some geological units (such as the Voltri, the Torino Hill and Monferrato units) could be ascribed to either orogens, depending on the criteria used. To avoid this kind of problems, we preferred to classify and describe the several lithotectonic units of Piemonte on the basis of: (i) the palaeogeographic- geodynamic context, in which they formed, (ii) the degree of preservation of their primary features, i.e., whether they have been metamorphosed or not, (iii) their present structural position (in a strict geometric and/or geographic sense). To achieve a suitable classifi cation of the several kinds of geological elements recognised in Piemonte, a Conceptual Model (Fig. 2) has been created in order to defi ne criteria for the hierarchical subdivisions reported in the Map Legend. This model provides several distinct hierarchy levels grounded on the above reported main palaeogeographical domains, in turn subdivided into diff erent tectonostratigraphic subdomains-orders (Fig. 2). The geological and structural subdivisions used in the Piemonte Geological Map are diff erent but not in contradiction with other classifi cation schemes of the geological literature, for instance with the classical subdivision of northwestern Alps and western Ligurian Apennines into three main structural domains (Fig. 4): (i) an internal (i.e., placed in the Padane realm of the Alps-Apennines orogen) domain (Southalpine Domain) belonging to the Adriatic plate and only partially involved in the Alpine orogenic process; (ii) an external domain (i.e., placed on the European side of the Alps mostly in France and Switzerland) corresponding to the Helvetic, Dauphinois, Provençal and (partially) to the External Briançonnais domains of the geological literature; (iii) a central (axial) part of the orogenic system, i.e. the Austroalpine- Penninic collisional wedge, corresponding to the continental and oceanic nappes bounded by two main tectonic discontinuities, the Canavese Line on the inner side and the Penninic Frontal thrust on the outer side, respectively (see Dal Piaz, 1999; Dal Piaz et al ., 2003; Beltrando et al ., 2010). These HP metamorphic units originally belonged to the Piemonte-Liguria oceanic Domain, to portions of the palaeo-European margin (Middle Penninic Briançonnais Domain, Lower and Upper Penninic Domains such as Monte Rosa, Gran Paradiso and Dora-Maira nappes) and/or to the palaeo-Adriatic margin (Austroalpine and Southalpine Domains). 28 Fabrizio Piana et alii

These classical subdivisions, although not used in the Map as discriminant criteria for the classiﬁ cation of Geologic Units, have been reported in some titles at the head of some «tile-blocks» of the Legend, or on lateral titles. It is worth noting that the «Alps-Apennines orogenic system» is used here as being comprehensive of all the geological units pertaining to both the Mesozoic palaeogeographical domains of the Western Alpine Tethys and the sedimentary successions deposited since the Eocene in the synorogenic basins whose evolution was controlled by the collisional interaction of the European and Adriatic plates. A brief description of the criteria used for the detailed representation of the Mapped Features is given in the following sections.

Lithostratigraphic criteria – metamorphic and sedimentary rocks The Map Legend was built using lithostratigraphic criteria, i.e., by subdi- viding rocks into Geologic Units based on their compositional and structural features, and on their further subdivisions into formal and/or informal lithostratigraphic units (formation, member, lithodemic unit). Consequently, the fi rst step for the lithostratigraphic classifi cation of the Geologic Units was their pertinence to either «Metamorphic» or «Non- metamorphic» rock classes. A metamorphic rock is intended here as a rock whose primary features are «mostly» (and not necessarily «completely») overprinted by secondary petrogenetic processes and whose main distinctive features (e.g., main foliation or layering) are due to dynamic internal re-orga- nization or mineralogical-chemical transformation consequent to increase of P-T conditions. Therefore, the Piemonte Geological Map Legend simply separates the «metamorphic» units from the «non-metamorphic» ones, and does not report any diff erentiation based on the metamorphic transformation degree («metamorphic grade») within each major Geologic Unit. In eff ect, these distinctions would have induced very great diffi culties in mapping in detail the boundaries between distinct metamorphic facies or metamorphic units, due to relatively scarce availability of such kind of data, because metamorphic maps of the Alps are available only at very large scale (Niggli, 1973; Frey et al ., 1974; Oberhänsli, 2004). Two steps were necessary to identify the Geological Units of the Map. The fi rst step was the identifi cation of the physical boundaries between the Geological Units that correspond to diff erent types of Geologic Structure of both tectonic origin (in the case of Lithotectonic Units) and of primary origin (Geological Contact). Among the Geological Contact, great importance has been given, for sedimentary successions, to the unconformities (« surface of Geological Map of Piemonte Region at 1:250,000 scale 29 erosion between rock bodies representing a signifi cant hiatus or gap in the stratigraphic succession»: Hedberg, 1976; Salvador, 1994) since these are correlatable at regional scale and thus very useful for mapping purposes. The second step was the attribution of the Geologic Units to a given Formation either to an informal lithostratigraphic unit for sedimentary successions, or to a lithodemic unit for metamorphic rocks. A lithodemic unit is a « lithostratigraphic unit that lacks stratifi cation» or that «does not conform to the Law of Superposition» (INSPIRE, Data Spec. on Geology, D2.8.II.4). Consequently, many of the Geologic Units must be grouped into higher rank subdivisions, such as: (i) Synthems (i.e., Unconformity-bounded stratigraphic units (UBSU, Chang, 1975; see also «International Stratigraphic Guide»: http://www.stratigraphy.org/index.php/ics-stratigraphicguide). The identifi cation of Synthems is based on objective criteria (such as the presence at the base of an angular unconformity, erosional truncation, abrupt facies and composition contrast contravening the «Walther rule») that can be used in the fi eld without the use of biostratigraphy (Clari et al., 1995a). The Synthems have also a chronostratigraphic value because their sediments, even if referable to diff erent depositional setting, are deposited during the same time interval and recording the same tectonostratigraphic events. (ii) Metamorphic complexes, intended as Geologic Units consisting of li- thodemes of more than one genetic class (North American Commission on Stratigraphic Nomenclature, 2005; Stratigraphy Commission of the Geological Society of London; see also the specifi cations of the Subcommission of Quaternary Stratigraphy, https://www.bgs.ac.uk/scmr/products.html).

Subdivision of Sedimentary Units Several unconformities have been recognized (Tab. 1) that allow to subdivide the stratigraphic successions into Synthems. Each Synthem, the fundamental unit of the Map Legend for the sedimentary successions, contains groups of coeval lithostratigraphic units (formations or members), already deﬁ ned in literature, and is bounded by regional-scale unconformities. The lithostratigraphic units are genetically related since originated in diﬀ erent but adjoining depositional systems during the same time interval. The use of Synthems allowed a correlation of sedimentary bodies geographi- cally separated, e.g., in the Pliocene succession and in the Tertiary Piemonte Basin (from Langhe to Borbera-Grue and Torino Hill-Monferrato system) or in the palaeo-European margin (Briançonnais and Dauphinois successions). In the marly or clayey successions, some unconformities (i.e., D4 and D8), which locally become hard to be recognized, have been tentatively extrapola- ted in the Map. 30 Fabrizio Piana et alii

The title of each graphical tile in the Legend reports the distinctive lithological features and the age of each Synthem, while the text describing each tile reports the list of the main lithostratigraphic units (both formalised and non-formalised) belonging to that Synthem.

Subdivision of Metasedimentary Units The Metasedimentary successions have been subdivided into the same stratigraphic units used for the non-metamorphic successions. For the metamorphic ones, these units cannot be considered properly as synthems but indeed as «parasynthems», as we informally defi ned this kind of units. The parasynthems (labelled as AC0, AC1, AC3, AML0, AML1, AML2, AML3, AML4m and AML5m) can be correlated through diff erent tectonic units of the Piemonte Western Alps on the basis of their primary lithologic, stratigraphic or chronostratigraphic characters. The criteria used for separating the parasynthems are the recognition (or the inference) of the main unconformities of Table 1 (from S0 to S4) and the related Geologic Events. Furthermore, some slivers of « incertae sedis sedimentary rocks», preserved as discontinuous and partially detached portions covering the polycyclic basement, have been also comprehensively grouped as «slivers of undiff erentiated metasedimentary covers». These also include the major gypsum-bearing fault rocks cropping out along the tectonic contacts separating the main lithotectonic units of the Piemonte Alps.

Classifi cation and representation of Quaternary successions The mapping of the continental Quaternary deposits had to deal with several methodological problems, summarised as follows: - heterogeneous dataset with diff erent geographic distribution, clustering and quality depending on representation scale; - diff erent criteria of analysis and interpretation of the available data due to diff erent aims of representation; - diff erent stratigraphic units adopted over time for continental units; from chronostratigraphy to lithostratigraphy (scale 1:100,000; Geological Map of Italy), morphostratigraphy, allostratigraphy and Unconformity-bounded Stratigraphy (scale 1:50,000; CARG Project); - scarcity or heterogeneity of available radiometric (i.e., 14 C, U/Th) and/or biostratigraphic data. The methodology, used for the offi cial Geological Map of Italy at the scale 1:50,000 (lithostratigraphy associated to Unconformity-bounded stratigraphic units and feeder catchments: Pasquarè et al ., 1992; Germani et al ., 2003), allows to solve many of the above mentioned problems, but the method seems Geological Map of Piemonte Region at 1:250,000 scale 31 unreliable for synthesis maps at smaller scale, in which detailed stratigraphic subdivisions can not be represented. Furthermore, correlations among units physically separated are defective without robust chronological data. In order to bypass these diffi culties, three sedimentary basins, which showed distinct morphologic and tectonostratigraphic features since latest Pliocene, were distinguished: The Western Po Basin, the Savigliano Basin, and the Alessandria Basin (sensu Irace et al ., 2009, 2017). Each basin consists of several depositional systems (such as end moraine, fl uvioglacial fan, alluvial megafan, etc.), related to major catchments, characterised by individual stratigraphic architectures as a response to tectonic and climatic events. For each sub-system, a detailed stratigraphy has been established on the base of unconformities (basal boundary and depositional top) bounding the sedimentary units. The major depositional systems were fi rstly separated using a morphostratigraphic approach and the digital elevation model of Piemonte Region, coupled with analyses of subsurface data. Subsequently, the hierarchy of the bounding surfaces was investigated connecting, where possible, surface and subsurface data. Finally, physical and chronological correlation of the systems was performed. Moreover, the deposits, located in mountain and hill areas outside the three above-mentioned basins, have been grouped into «ubiquitous deposits», as defi ned by Polino et al . (2002) and Bini et al . (2004). For these deposits, the parameters of stratigraphic correlation are inapplicable because of the im- possibility of extending in the catchments of mountain areas the stratigraphic subdivision used in the plain sectors. The modern fl uvial riverbeds, whose correlation is possible throughout the region, were also included in the ubiquitous deposits.

Tectonic criteria (main tectonic contacts and faults) The Map reports two distinct hierarchy levels of tectonic Geological Contacts («Shear Displacement Structure» - SDS sensu GeoSciML): –fi rst level: tectonic contacts between fi rst-order Geologic Units (tectonometamorphic units and tectonostratigraphic units) –second level: faults and shear zones developed within a single Geologic Unit or cutting across diff erent Geologic Units. Kinematic information, related to the sense of movement of the tectonic features, is not included in this version of the Map, but they are available on the WebGIS service. The intensively deformed units (i.e., tectonic slices or shear zones), bounded by SDS and whose present internal structural setting is mainly due to shearing, have been identifi ed as a Deformation Unit sensu GeoSciML. 32 Fabrizio Piana et alii

5. Brief outline of the Piemonte geology A brief, synthetic description of the main geological features of Piemonte, referred to its main orographic features, is given below. The geomorphological framework of Piemonte Region is characterised by several orographic features: the Alps and Apennines mountain ranges, the hills of Monferrato, Langhe and Alto Monferrato, and the wide alluvial plain of the Po River.

The northern and central parts of the Piemonte Alps, represented by the Cottian Alps and parts of the Graian, Pennine and Lepontine Alps, display the deeper crustal portions of the Alps-Apennines orogenic system, aﬀ ected by both pre-Alpine and Alpine metamorphisms. They are represented by:

–the lower crust and lithospheric mantle rock slices («Ivrea-Verbano Zone» and «Second Diorite-Kinzigite Zone» or IInd DK); –the intermediate continental crust of the Dora-Maira, Gran Paradiso, Monte Rosa massifs/nappes and of the Lepontine nappes, referred to the palaeo- European continental margin; –the Late Carboniferous-Mesozoic palaeo-European sedimentary «cover», showing variable degree of metamorphic transformations and locally unconformably overlain by the Alpine Foreland Basin succession; –the meta-ophiolites and associated metasediments of the Mesozoic Piemonte-Liguria and Valais oceanic domains; –the highly transformed mainly polycyclic metamorphic rocks of the Austroalpine «Sesia-Lanzo Zone» and of the Southalpine basement (Massiccio dei Laghi), all referred to the palaeo-Adriatic continental margin; –the Permian volcanic and volcaniclastic sequences of Biellese and Valsesia, unconformably overlain by Mesozoic carbonate successions, locally preserved at the outlet of Sesia and Sessera valleys.

The southern part of the Piemonte Alps (corresponding to the Maritime and Ligurian Alps) is characterised by polycyclic rocks (continental crust of the Argentera Massif and Gran San Bernardo and Ligurian Briançonnais basements), Permian continental and volcaniclastic sequences covered by Mesozoic carbonate successions of the palaeo-European margin, in turn unconformably covered by Eocene to Pliocene sediments of the synorogenic basins. The Western Alps show a double-vergent tectonic setting (Roure et al ., 1990, 1996; Pﬁ ﬀ ner et al ., 1997; Rosenbaum et al ., 2002) that is the result of Geological Map of Piemonte Region at 1:250,000 scale 33 the convergence between the Europe and Adria plates. Three main structural sectors, partly corresponding to Mesozoic palaeogeographic realms, have been distinguished (see Dal Piaz et al ., 2003; Schmid et al ., 2004; Beltrando et al., 2010 for a review):

–an internal sector, belonging to the upper plate of the collisional system («Southalpine» domain) made up of a Variscan and pre-Variscan basement with lower continental crust and upper mantle rocks, covered by Permian volcanics and volcaniclastic deposits and a Mesozoic sedimentary succession. This sector is bounded by the Periadriatic Lineament (Insubric Fault, Canavese Line) and by the south- to southeast vergent thrust fronts on its Padane side; –an external sector, belonging to the lower plate of the collisional system («European» foreland area: Helvetic–Dauphinois and Provençal domains) made up of Variscan polycyclic basements and Late Carboniferous to Permian sedimentary successions and intrusive bodies, Mesozoic sedimentary covers and Cenozoic synorogenic deposits («ﬂ ysch»), which underwent only anchizone to subgreenschist-facies metamorphism. The external sector is bounded on its western and south-western side by frontal thrust systems separating the Alpine belt from the foreland domains; –an axial sector bounded by two crustal scale discontinuities, corresponding externally to the Penninic frontal thrust and internally to the Insubric tectonic lineament (Canavese fault system) internally. This sector is made up of a complex tectonic assemblage including Variscan and pre-Variscan continental basement units, Late Carboniferous to Permian metasedimentary and metavolcanic covers, oceanic lithosphere and relevant Cretaceous to Paleocene (?) sedimentary units of the Liguria-Piemonte oceanic domain, facing the continental margins. This sector underwent Alpine metamorphism ranging from greenschist-facies to blueschist- and eclogite- facies (locally ultra high pressure, UHP) conditions.

In the Piemonte region, the axial and the internal (Adria-vergent) tectonic belts are the dominant units. The Europe-vergent tectonic front (Briançonnais External Front) and relevant foreland fold-and-thrust belt are exposed only in the southwestern part of the region (Maritime and Western Ligurian Alps). In the Western Alps, at scale of the whole chain, a complex kinematic framework (involving extensional, contractional and strike-slip tectonics) dominates in the internal sectors, whereas a coeval contractional kinematics aﬀ ects the external sectors (Tricart, 1984; Schmid et al ., 1987; Laubscher, 1988, 1991; Roure et al ., 1990; Laubscher et al ., 1992; Biella et al ., 1997; 34 Fabrizio Piana et alii

Delacou et al ., 2004; Handy et al ., 2010; Dumont et al ., 2011; for a review see also Dal Piaz, 2010; Molli et al., 2010).

In Piemonte, the Apennine mountain range extends from the southwestern part of the region, east of Cadibona Pass, to the southeastern parts along the boundary with Emilia-Romagna and Lombardy regions. From the Cadibona Pass to the Lemme Valley, the Apennines show polycyclic basement rocks and the overlying Mesozoic carbonate successions of the palaeo-European margin, as well as metamorphic rocks derived from the oceanic Liguria-Piemonte Domain (from the Erro Valley to the Lemme Valley). All these units, known in the geological literature as «Ligurian Alps», are presently covered by sedimentary terrigenous successions of the late Eocene to Pliocene synorogenic basins. The northeastern sector of the Apennines (to the northeast of the Lemme Valley) shows non-metamorphic rocks mainly derived from the oceanic Liguria-Piemonte Domain or the synorogenic basins. These units represent the shallower part of the orogenic system, not involved in deep tectonic processes but obducted over the Adriatic continental margin. This sector, from a geological point of view, is part of the Northern Apennines, a tectonic belt formed since the Late Oligocene in response to the overthrusting, toward E and NE, of internal (oceanic) and external Ligurian units onto the palaeo-Adriatic continental margin (Elter, 1973). This tectonic belt is covered by «epi-Ligurian» successions (Ricci Lucchi, 1986) deposited since the Eocene in several synorogenic basins. The northern Apennine tectonic belt overthrusts toward the north and northeast the Tertiary sediments of the Po plain subsurface (Pieri & Groppi, 1981; Cassano et al ., 1986; Falletti et al ., 1995; Biella et al ., 1997), and the underlying Mesozoic sedimentary units, which represent the southward prolongation of the Southern Alps (Adria crust), as shown by seismic data.

The central sector of the region is mainly characterised by sedimentary successions of synorogenic basins (Tertiary Piemonte Basin Auct. and Pliocene basins), which were aﬀ ected, although less deeply, by the same tectonic processes (in regards to age and kinematics) involving the other parts of the orogenic system. As a result, these sedimentary successions continually recorded the geological evolution of the Piemonte Alps-Apennines orogenic system. The sedimentary units of the synorogenic basins, deformed and uplifted during Cenozoic and Quaternary times, presently form the hills of the Langhe, Alto Monferrato, Monferrato and Torino Hill. The more recent (Quaternary) units of the synorogenic basins are located along the major rivers dissecting the Alpine and Apennine reliefs and form the Padane alluvial basin, where they form the Vercelli and Novara alluvial plains (placed to the north of the Torino Hill- Monferrato system) and, to the south, the Savigliano and Alessandria basins. Geological Map of Piemonte Region at 1:250,000 scale 35

The deposition of the Quaternary successions has been controlled by both recent tectonics, accountable for horizontal and vertical movements of the order of a few millimetre/year, and gravity forces that can induce correlati- ve movements of rock masses of the order of tens millimetre/year (Eva & Solarino, 1998; Delacou et al ., 2004; Morelli et al ., 2011; Perrone et al ., 2013 with references). For this reason, all Quaternary deposits reported in the map have been considered as eﬀ ective parts of the Alps-Apennines system in ongoing development, since at present they occur in other more eastern sectors of the Padane realm (Scardia et al., 2015 with references). The subsurface of the Piemonte region (Fig. 9) is characterised, to the north of the Po River below the alluvial planes, by sedimentary units of the palaeo- Adriatic margin, folded and overthrust to the south. South of the Po River, the synorogenic basin deposits (partially corresponding to the so called «Tertiary Piemonte Basin», see below) mask both the tectonic boundary between the palaeo-European metamorphic units and the non-metamorphic sedimentary units belonging to the eastern margin of the Liguria-Piemonte domain and the palaeo- Adriatic margin (Cassano et al ., 1986; Falletti et al ., 1995; Piana & Polino, 1995; Biella et al ., 1997; Piana, 2000; Mosca, 2006; Mosca et al ., 2005, 2009).

6. Description of the map legend Synorogenic basins The sedimentary successions deposited, since the Eocene, in the Alps- Apennines synorogenic basins have been distinguished into (Figs. 5, 6, 7): –the Quaternary succession; –the Pliocene succession; –the «Tertiary Piemonte Basin» (BTP) succession (Eocene to Messinian); –the «Alpine Foreland Basin» succession (middle Eocene to early Oligo- cene).

The Quaternary succession Deposits of the Alps and Apennines reliefs. The continental deposits (col- luvial, gravitational and periglacial), located in the mountain and hilly sectors of Piemonte, have been generically considered as «ubiquitous deposits» sensu Polino et al . (2002) and Bini et al . (2004). The glacial deposits of the valley sides, the present-day and the terraced alluvial sediments along riverbeds in the mountain and hilly domains, whose correlation is theoretically possible throughout the region, were also considered as «ubiquitous deposits».

Alluvial and debris fl ow deposits (fl 1). They correspond to the active me- andering riverbeds and to the terraced surfaces, a few metres high, which 36 Fabrizio Piana et alii have been partially to completely fl ooded. In the mountain areas they include gravelly alluvial deposits, locally fi lling intermountain basins created by landslide damming events (i.e., Salbertrand-Oulx basin in the Susa Valley and Pourrieres basin in the Chisone Valley (Tropeano & Olive, 1993; Polino et al ., 2002; Fioraso & Baggio, 2013), and debris fl ow dominated fans, built up by tributary streams or by glacial dynamics. Holocene-Present.

Terraced alluvial and debris fl ow deposits (fl 2). Undiff erentiated alluvial gravel and sand, hanging at diff erent elevations above the present drainage network, for which morphostratigraphic criteria have not been applied. In the mountain areas, these units include deeply dissected fans feeded by debris fl ow. Upper Pleistocene-Holocene.

Lacustrine, palustrine and peat bog deposits (lc). Fine-grained sandy-silty deposits occasionally associated with peat deriving from the ﬁ lling up of wide depressions formed after the retreat of glaciers (e.g., Rivoli-Avigliana and Ivrea end moraine systems: Petrucci et al ., 1970; Balestro et al ., 2009; Gianotti et al ., 2015) or created by landslides or glacial dams (Fioraso et al ., 2011; Bigioggero et al., 1981). Middle Pleistocene-Present.

Large and giant landslide accumulations and deep-seated slope deformations (ld). Major landslides accumulations (volume > 10 Mm 3) located in the alpine (e.g., Mount Ciantiplagna rock avalanche: Fioraso & Baggio, 2013) and hilly environments (e.g., Feisoglio-Cravanzana rock block slide in the Belbo Valley), generally evolved since the Last Glacial Maximum (LGM) (Tropeano & Olive, 1993). Deep-seated gravitational slope deformations were also included, such as the San Sicario and the Sauze d’Oulx rock ﬂ ows of the upper Susa Valley (Fioraso et al., 2010). Upper Pleistocene-Present.

Block stream deposits (bs). They are characterised by debris streams up to about 10 m thick, laid on weathered diamicton up to 20-30 m thick. Litho- logically controlled and localized only on the Lanzo ultramaﬁ c massif, these deposits derive from long term weathering processes of lherzolite associated with creeping phenomena at the expense of the pedogenetic products and subsequent segregation of blocks with sifting mechanisms (Fioraso & Spa- gnolo, 2009). Lower Pleistocene-Holocene.

Post Last Glacial Maximum active and inactive rock glacier (rg). They correspond to the major rock glaciers developed during the glacier withdrawal since the Last Glacial Maximum (LGM) (Balestro et al ., 2013). Late Upper Pleistocene-Present. Geological Map of Piemonte Region at 1:250,000 scale 37

Glacigenic deposits (gl). They include lodgement and supraglacial melt- out till and ice-contact deposits located in the Alpine valleys, which developed essentially in the Last Glacial Maximum and subsequent glacial stages. Because of the uneven distribution and dating, only those with clear morphological evidence (e.g., moraine and glacial terrace) were represented. Major end moraine systems, developed from the Little Ice Age onward, are included (Lucchesi et al., 2014). Middle Pleistocene-Present. Deposits of the alluvial plains and end moraine systems. Three major basins were distinguished: –the Western Po Plain Basin, –the Savigliano Basin, and –the Alessandria Basin. Each of them, having had underwent a similar Quaternary evolution, shows partially diff erent morphology and tectonostratigraphic architecture. The bor- ders of the basins correspond to the orographic reliefs of the Alps, Torino Hill, Monferrato and Langhe domains, or to morphotectonic thresholds related to Quaternary activity of the regional tectonic features. Western Po Plain Basin. The Western Po Plain Basin is separated from the Savigliano Basin by the Moncalieri threshold, which corresponds to the morphological evidence of the buried Torino Hill anticline. Across this threshold, formed by the tectonic uplift of the Torino Hill anticline (Perrone et al ., 2013), a sharp change in the pattern of the fl uvial network occurs: To the North of the Torino Hill threshold, the erosional trenching of the major rivers (Po, Sangone, Dora Riparia and Stura di Lanzo) into their own fl uvioglacial and alluvial fans prevails, whereas to the South, sinking is dominant, with the consequent aggradation of the alluvial plain between Moncalieri and Carmagnola. The Western Po Plain Basin is separated from the Alessandria Basin by the Valenza-Tortona threshold, at the junction between the Po, Tanaro and Scrivia rivers. This area represents a structural high, possibly due to the activity of the Monferrato thrust front, which separates two gently subsiding areas: The Alessandria plain and the Lomellina sector (Devoti et al ., 2011; Giraudi, 2015). The deposits referred to the Western Po Plain are related to the Po drainage basin from the confl uence with the tributary Sangone River to the confl uence with the Ticino River. In this sector, eight units related to fl uvial, fl uvioglacial and glacial environments, respectively, have been distinguished and labelled from P9 to P15. Unit P9 («Villafranchiano C»; lower Pleistocene) forms isolated outcrops on the northern border of the Western Po Plain (e.g., along the Cervo, Elvo 38 Fabrizio Piana et alii and Ticino rivers). It mainly consists of coarse- to fi ne-grained fl uvial deposits, locally spotted by paralic muds with brown coal remnants (Cervo River: Martinetto, 2001). They are unconformably sandwiched between the underlying S8c and the overlying P13 to P15. Unit P10 (lower Pleistocene), made up of gravelly fl uvial deposits, refers to the oldest aggradation phase preserved in the basin (Carraro et al ., 1991). It forms the most external surfaces of the Stura di Lanzo alluvial fan (Balestro et al ., 2009) and the topmost terrace of the Trino Vercellese isolated relief (Giraudi, 2014). The following P11 , P12 and P13 units (lower and middle Pleistocene) are made up of fl uvioglacial and glacial deposits of the Verbano, Cusio, Ivrea, Cuorgné and Rivoli-Avigliana end moraine systems (Figs. 14, 15), referred to as glacial/interglacial cycles before the MIS 5e (Marine Isotope Stage 5e). These units also correspond to the terraced alluvial megafans located at the mouth of the Cervo and Stura di Lanzo valleys. Unit P13 includes the fi ne-grained alluvial deposits of the Valenza plateau, a system of coalescing alluvial fans fed by minor tributaries draining the eastern Monferrato northern fl ank. Units P14 and P15 are related to the upper Pleistocene glacial and fl uvioglacial phases and the post-Last Glacial Maximum (LGM) recognizable in the end moraine systems (Malaroda, 1998; Balestro et al ., 2009 a; Gianotti et al ., 2008, 2015). Lastly, unit P16 (upper Pleistocene-Holocene) corresponds to broad alluvial terraces perched above the present fl oodplain ( fl 1 ) of the Po River along the northern side of the Torino-Monferrato hills (Dela Pierre et al ., 2003 a; Giraudi, 2014). Savigliano Basin. The deposits of the Savigliano Basin are confi ned by the present confi guration of the Po River, upstream the confl uence with the San- gone River. To the same basin are also ascribed the sediments of the Tanaro catchment upstream of Bra, which deposited, according to Carraro et al . (1995), before and after the Upper Pleistocene capture of the river towards the Ales- sandria basin. In the Savigliano Basin (see also Bottino et al ., 1994), nine units were distinguished, related to fl uvial, fl uvioglacial, and glacial environments. Unit S9 («Villafranchiano C»; lower Pleistocene) groups the continental units referred to as the Villafranca d’Asti type area «upper complex» (Carraro, 1996; Forno et al ., 2015). It consists of coarse- to fi ne-grained fl uvial deposits, cropping out along the NE border of the basin, unconformably encased by the S8c below and S11 above. Units S10 and S11 (lower and lower-middle Pleistocene) form the wide alluvial plateau of Fossano, Salmour, Magliano Alpi, Mondovì and Chiusa Geological Map of Piemonte Region at 1:250,000 scale 39

Pesio (Kerckhove, 1980). To the north, the Poirino plateau (Forno, 1982) and other dissected alluvial fans at the outlet of the Po, Pellice and Chisone valleys were included in these units. Units S12 and S13 (middle and middle-upper Pleistocene) are represented by telescopic megafans (e.g., Maira, Grana and Stura di Demonte alluvial fans) or terraced megafans of the Chisone and Pellice rivers. These units include the small end moraine related to the repeated advances of the Stura di Demonte glacier (Malaroda et al., 1970; Biancotti, 1979). Unit S13 predates the deepening of the palaeo-Tanaro (unit S14) and the capture of the Tanaro River towards the Alessandria Basin, which occurred before the Last Glacial Maximum (Carraro et al., 1995). Finally, units S15, S16 and S17 (late upper Pleistocene-Holocene) consist of remnants of terraces located within the trenches of the Stura di Demonte and Tanaro rivers and related tributaries. Alessandria Basin. The deposits of the Alessandria Basin are related to the Tanaro River catchment (downstream of Alba) and its right tributaries, Belbo, Bormida, Scrivia and Curone rivers. Seven alluvial units have been distinguished. Unit A9 («Villafranchiano C»; lower Pleistocene) is made up of a coarse- grained fl uvial stack continuously exposed throughout the basin (Irace et al ., 2017; d’Atri et al ., 2016b). The stack unconformably rests on S8c or S8b and is unconformably overlain by Units A10 to A13. Units A10 , A11 and A12 (lower and middle Pleistocene), correspond to the high plateaus (remnants of ancient alluvial fans) at the outlet of the major rivers catchments in the Alessandria plain (d’Atri et al ., 2016b). In the Quargnento- Solero plateau, to the northeast of Alessandria, unit A12 is represented by coalescing alluvial fans, made up of fi ne-grained deposits, feeded by minor tributaries of the southern fl ank of eastern Monferrato. In the Langhe domain, in particular in the Bormida and Orba valleys, these units constitute terrace staircases elevated up to 220-230 m above the present valley fl oors (Gelati et al ., 2010a; d’Atri et al ., 2016b). The distribution of these surfaces defi ne fl ow directions slightly diff erent from the present ones and represent a sequence of erosion/deposition episodes connected to the progressive uplift of the Langhe hills and involving increasingly large portions of the Alessandria Basin. The units A13, A14 and A15 (upper Pleistocene and Holocene) represent distinct accretionary and trenching cycles of the Bormida, Scrivia and Curone rivers as a response to the diff erential tectonic activity involving the uplifting Langhe domain and the subsiding Alessandria basin (Devoti et al ., 2011; d’A- tri et al ., 2016b). Unit A13 includes the megafan of the Scrivia and Curone rivers. 40 Fabrizio Piana et alii

The Pliocene succession and the Tertiary Piemonte Basin The Quaternary successions of the Savigliano, Alessandria and Western Po basins rest on a continuous upper Eocene to Pliocene succession, largely exposed in the Monferrato, Alto Monferrato and Langhe hills, which can be correlated at regional scale. It is worth noting that during Pliocene, the present Alessandria and Savigliano Basins were connected through the Asti swell to form a single large thrust-top basin. This basin was separated from the Ligurian Sea by the Ligurian Alps (Bertotti & Mosca, 2009) and was likely connected to the coeval Po Foreland Basin through deep to shallow seaways localized on the Torino Hill and Monferrato structural high (Boni & Casnedi, 1970; Dela Pierre et al ., 2003 a,b). Only during the Pliocene-Pleistocene transition, the progressive uplift of these structural domains, including the Asti area (Irace et al ., 2017), played an important role in the reduction of the lateral continuity of the Pliocene basin and the embryonic establishment of the Savigliano and Alessandria depozones, to the south, and of the Po Foreland Basin to the north. Therefore, the term «Pliocene southern Basin» is used here to indicate the continuous Pliocene basin, developed south of the Torino Hill and Monferrato, whereas the notation «Pliocene Padane Basin» groups the successions deposited to the north. Accordingly, the synthems recognised in the Pliocene succession have been correlated throughout the entire Piemonte region. The Pliocene succession has been kept separated from the middle Eocene to Messinian succession of the so-called «Tertiary Piemonte Basin» (BTP). The main lithostratigraphic units of the Pliocene and BTP successions were correlated at regional scale and their complex nomenclature was simplifi ed. The correlations were made possible by the availability of both biostratigraphic data (Novaretti et al ., 1995; Fornaciari et al ., 1997a, b; Steininger et al ., 1997) and the newly published 1:50,000 geological maps (sheets: n.156 «Torino Est», 157 «Trino», 178 «Voghera», 194 «Acqui Terme», 196 «Cabella Ligure», 211 «Dego», 213-230 «Genova», 228 «Cairo Montenotte»). The Pliocene succession. The Piemonte Pliocene succession was subdivided into three lithostratigraphic units, mapped at regional scale: from base to top, the Argille Azzurre Formation (basin to outer shelf deposits; S7a and S8a ), the Sabbie di Asti Formation (inner shelf deposits, S7b and S8b ), and the «Villafranchiano» Auct . (nearshore, tide-dominated and continental deposits; S7c , S8c and S8d ). Complex lateral stratigraphic relationships and time-transgressive boundaries also exist between these deposits, which have diff erent ages – from Zanclean to Piacenzian – in diff erent parts of the basin. Moreover, the «Villafranchiano» deposits extend until the early Pleistocene (see below and section «Quaternary succession»). Geological Map of Piemonte Region at 1:250,000 scale 41

Based on surface and sub-surface data (Vigna et al ., 2010; Irace et al ., 2009, 2010), the stratigraphic relations and geometry of Pliocene units were deﬁ ned. Three unconformities (D7, D8, D9) subdivide the Pliocene succession into two regressive synthems.

Unconformity D7 It mainly corresponds to a paraconformity, evidenced by a sharp facies change between the Messinian ﬂ uvio-deltaic and lacustrine successions of Synthem 6 ( S6a) and the Zanclean basin plain successions of Synthem 7 ( S7a). The D7 records the marine ﬂ ooding, following the sudden re-establishment of the Atlantic connections at the end of the Messinian salinity crisis (Iaccarino et al ., 1999; Trenkwalder et al ., 2008; Dela Pierre et al ., 2011; Violanti et al ., 2011; Violanti, 2012). The D7 is interpreted as the maximum landward shift of the shoreline at the base of the Pliocene (Roveri et al ., 2003, 2008). The D7 has been represented only in the Pliocene southern Basin, whereas in the northern margin of the Pliocene Padane Basin it merges into D8.

Synthem PLI 7. It consists of a Zanclean coarsening upward sedimentary stack, cropping out only in the southern margin of the Pliocene southern Basin, and made up of marly, silty and sandy deposits, overlain by sandy-gravelly sediments. This stack represents, after the basal Pliocene transgressive phase (D7 unconformity), the ﬁ rst step of the «Pliocene progradation» (Vigna et al ., 2010; Irace et al ., 2010; Ghielmi et al ., 2013) that, starting from the southern domains, generated a northward basin-scale regression of coastal (S7c ), shelf ( S7b ), and slope to basin plain ( S7a ) depositional systems (Pavia et al ., 1989; Violanti & Giraud, 1991; Vigna et al ., 2010; Violanti, 2012). Prograding continental and shelfal deposits of synthem PLI 7 are only preserved in the southwesternmost portion of the basin at the western edge of the Langhe, whereas genetically related deep water successions mostly occur along the northern border of Langhe, Alto Monferrato and Borbera-Grue domains.

Unconformity D8 It corresponds to an erosional surface of semi-regional extent, which splits the Pliocene regressive succession into two progradational synthems (PLI 7 and PLI 8). It has been recently referred by Vigna et al . (2010) to the «intra-Zanclean tectonic phase», based on the correlation with the tectonic- driven «intra-Zanclean unconformity», recognised in the Po Foreland Basin (Ghielmi et al ., 2013). In the southwestern margin of the Pliocene southern Basin, the D8 is characterized by a smooth angular unconformity (Vigna et al ., 2010) and by a sharp facies change from Zanclean sandy silty shelfal 42 Fabrizio Piana et alii successions of synthem PLI 7 ( S7b) to the Piacenzian silty and sandy gravelly continental successions of synthem PLI 8 ( S8c). This change indicates an abrupt decrease in the water depth, related to the uplift of the southern margin of the basin (Vigna et al ., 2010). This induced a fast downward shift of basin margin (alluvial plain, nearshore and shelfal) environments and the rapid northward progradation of the slope systems, which led to the complete ﬁ lling of the basin during late Zanclean-Piacenzian. The erosional impact associated with the D8 unconformity gradually decreases towards the northeastern part of the basin and grades into a paraconformity (d’Atri et al ., 2016b), placed between the Zanclean marly silty and sandy basin plain successions (S7a) and the Zanclean-Piacenzian silty marly slope successions (S8a). In the Pliocene Padane Basin, the D8 unconformity changes to a nonconformity between the bedrock (Southalpine and Austroalpine domains) and the component units of Synthem 8, marking the diachronous beginning of Pliocene marine to continental sedimentation (S8b and S8d) on the exhumed substratum.

Synthem PLI 8. It is made up of a regressive succession, spanning the late Zanclean-Piacenzian time interval and representing the second step of the northward «Pliocene progradation» (Vigna et al ., 2010; Ghielmi et al ., 2013). In the southern margin of the Pliocene southern Basin, synthem PLI 8 rests, through D8, on synthem PLI 7. Along the northern margins, synthem PLI 8 directly overlies synthems 4, 5 and 6, because synthem PLI 7 is mis- sing or is very condensed, and the D7 and D8 surfaces merge into a single unconformity. Moving from the WSW towards the NE (basinward), silty and gravelly fl ood-plain deposits and sandy tide-dominated nearshore sediments (S8c) overlay and laterally grade into sandy to gravelly shelfal deposits ( S8b), which in turn pass to slope and basinal silty marls (S8a). By contrast, along the northern margin of the Pliocene Padane Basin, synthem PLI 8 directly rests on top of the units of the Southalpine domain. This regression is testifi ed by the migration, from WNW to ESE, of prograding coarse- to fi ne- grained continental deposits ( S8d; Martinetto et al ., 2007) and sandy to gravelly nearshore and shelfal successions (S8b; Aimone & Ferrero Mortara, 1983; d’Atri & Piazza, 1988; Bertoldi & Martinetto, 1995; Basilici et al ., 1997; Ferrero et al ., 2005). Furthermore, isolated remnants of synthem PLI 8 are preserved along the northern rim of Monferrato, where epibathyal (S8a) to neritic ( S8b) successions unconformably overlay upper Eocene to Messinian sediments (Violanti, 2012). Consequently, it follows that: –each of the two above mentioned marine Pliocene formations (Argille Azzurre and Sabbie di Asti) is now subdivided into two informal Geological Map of Piemonte Region at 1:250,000 scale 43

lithostratigraphic units («a» and «b»): «a» belongs to Synthem 7 ( S7a and S7b) and «b» to Synthem 8 (S8a and S8b); –the deposits, previously referred to as «Villafranchiano», are here subdivided by the D8 and D9 unconformities into three informal lithostratigraphic units: Villafranchiano a ( S7c ; Zanclean), Villafranchiano b (S8c in the southern part of Piemonte, Fig. 12d; S8d in the Padane realm; Zanclean-Piacenzian), Villafranchiano c (early Pleistocene; A9, S9 and P9 ). The term «Villafranchiano» is maintained in the legend solely for historical reasons to indicate the transitional and coarse- to ﬁ ne-grained continental successions of Zanclean-early Pleistocene age, which in the Piemonte region are sandwiched between the Pliocene marine succession and the Quaternary gravelly continental sediments. However, this term should be abandoned in the future, as the term «Villafranchiano» refers to a Mammal Age (Rook & Martinez-Navarro, 2010 and references therein), corresponding to the Piacenzian (from 3.5 to 2.6 Ma) and Gelasian and Calabrian p.p ., from 2.6 up to 1.1 Ma, near to the base of the Jaramillo north magnetic polarity subchron.

Unconformity D9 The D9 surface rests above the Pliocene regressive succession and marks the base of three physically separated ﬂ uvial stacks of early Pleistocene age (Villafranchiano C), in the Savigliano ( S9 ), Alessandria (A9 ) and Western Po (P9 ) depocentres. Such depocentres are in turn separated by the Asti threshold, the Torino Hill-Monferrato relief, and the Moncalieri and Valenza-Tortona thresholds, respectively. D9 is an erosional surface, comprising a subtle angular unconformity, which locally cuts down to the Zanclean-Piacenzian sandy gravelly successions. It has been recently attributed by Vigna et al . (2010) to the «Gelasian tectonic phase», based on the correlation with the tectonic- driven «Gelasian unconformity», recognized at the seismic scale in the Po Foreland Basin (Ghielmi et al ., 2013). Notwithstanding the tectonic character of this unconformity, it has been recently suggested that climatic oscillations might have ampliﬁ ed the tectonic signal and that this surface might actually be considered as the sum of multiple erosive events ranging from the latest Piacenzian to the Gelasian (Irace et al., 2016).

The Tertiary Piemonte Basin Auct. (BTP) In the western Mediterranean, the Oligocene to Burdigalian tectonic stage, which is related to the opening of the Balearic Sea and anticlockwise rotation of the Corsica-Sardinia microcontinent (‘Balearic stage’: e.g., Castellarin, 1992; Finetti & Del Ben, 2000), induced the overthrusting of the Ligurian 44 Fabrizio Piana et alii units onto the palaeo-Adriatic continental margin. During this stage, some synorogenic basins (presently scattered from southern Piemonte to northern Apennines) developed on top of the overthrusting Ligurian units (Epiligurian basins of the northern Apennines: Cibin et al ., 2003), as well as on the western suture zone of the Ligurian realm (Castellarin, 1994) over the exhumed Eocene HP/LT metamorphic complex of the Ligurian Alps (Tertiary Piemonte Basin). In this sense, the term Tertiary Piemonte Basin is used to indicate the Oligocene to Messinian continuous sedimentary succession deposited in the above described episutural basin, which can be correlated through the diff erent geostructural composite domains of southern Piemonte (Torino Hill, Monferrato, Langhe, Alto Monferrato and Borbera-Grue). Gelati and Gnaccolini (1982) originally named this basin as the «Ligure-Piemontese» Tertiary Basin. This term was abandoned in the nineties and replaced by «Tertiary Piedmont Basin». Here, the «Tertiary Piemonte Basin» («BTP» in the Italian spelling) notation (fi rstly introduced by Miletto and Polino, 1992) is preferred, because it indicates the Italian name of the region (Piemonte) where the BTP is widespread. It is important to remark that «BTP» is used here according to its original meaning, i.e., the upper Eocene to Messinian sedimentary successions of southern Piemonte and adjoining areas. The term BTP, previously used to indicate in a more restrictive sense only the sedimentary successions of Langhe, Alto Monferrato and Borbera-Grue geostructural domains, is rejected because it is not suitable for regional geological correlations and mapping. In fact, the BTP successions are very similar, so that they can be correlated throughout the region, despite the eff ects of Pliocene tectonics and sedimentation. Although strongly controlled by synorogenic tectonics, these successions were deposited in a single upper Eocene-Miocene basin and aff ected by coeval tectonodepositional events marked by unconformities, which can be traced at a regional scale.

The BTP succession has been subdivided into six synthems bounded by seven unconformities having chronostratigraphic signiﬁ cance, and are described as follows:

Unconformity D0 (Priabonian) This nonconformity surface occurs at the base of the BTP succession. It can be recognized above the Ligurian Units, at the base of the Priabonian marly successions of Synthem 0 in Monferrato, Borbera-Grue and Torino Hill. It seals the meso-Alpine tectonic structures and marks the beginning of deposition in the retroforeland «epi-mesoAlpine basin» (sensu Mutti et al., 1995).

Synthem BTP 0 . It consists of deep water Priabonian marly successions (S0a) (Marne di Monte Piano, Marne di Vigoponzo) whose primary Geological Map of Piemonte Region at 1:250,000 scale 45 sedimentary contact with the underlying Ligurian units is badly and rarely preserved at surface.

Unconformity D1 (lower part of Rupelian) In the southern part of the BTP, it consists of a nonconformity surface between the bedrock (either metamorphic or non-metamorphic) and the overlying sedimentary successions of the BTP. It corresponds to the end of the main exhumation phase of the Alpine HP metamorphic units («Ligurian phase II» sensu Mutti et al ., 1995) and to the beginning of sedimentation (either continental or marine) on the exhumed basement (Federico et al ., 2004, 2005). In the northern part of BTP, it consists of an unconformity between the Priabonian marly successions of Synthem BTP 0 and the shallow water coarse-grained deposits of the base of Synthem BTP 1.

Synthem BTP 1. It begins with continental to shallow water Rupelian conglomerates and arenites (Lorenz, 1969) (S1a) (Formazione di Molare, Formazione di Cardona, Formazione di Ranzano, Conglomerati di Savignone, Arenarie di Rio Trebbio, Formazione di Grue, Formazione di Dernice), followed by Rupelian-Aquitanian hemipelagic marls (S1b) (Formazione di Antognola, Formazione di Rigoroso, peliti della Formazione di Rocchetta- Monesiglio, Formazione di Castagnola, Membro di Nivione della Formazione di Gremiasco, Formazione di Monastero) with interbedded arenaceous to conglomeratic resedimented bodies (S1c) (Formazione di Variano, Membro delle arenarie di Noceto e Membro delle arenarie di Castelnuovo di Ceva della Formazione di Rocchetta-Monesiglio, Membro delle arenarie di Cassinelle della Formazione di Rigoroso) (Gelati et al ., 1993, 2010b; Clari et al ., 1987). The Synthem is closed by Aquitanian-lower Burdigalian siliceous slope deposits (S1d) (Membro di Case Poggi della Formazione di Rocchetta-Monesiglio, Membro di C. Colombara della Formazione di Costa Montada, Membro si- liceo della Formazione Montechiaro d'Acqui, Marne a Pteropodi inferiori, Formazione di Contignaco, Marne di Montebrugi).

Unconformity D2 (lower Burdigalian) It is an angular unconformity corresponding to a Chattian-lower Burdigalian hiatus recognizable at the base of the shallow water carbonate deposits of Synthem BTP 2 (Monferrato, Alto Monferrato, Borbera Grue). In the deep- water areas (Langhe, Torino Hill), it laterally grades to the corresponding conformity. The D2 discontinuity surface formed during the Burdigalian event and led to a major reshaping of the basin (Clari et al ., 1995b; Falletti et al ., 1995; d’Atri et al ., 1997; Festa et al ., 2014), which began to be subdivided in structural highs and lows. 46 Fabrizio Piana et alii

Synthem BTP 2. It consists mainly of Burdigalian shallow water carbonate and glaucoarenite deposits that laterally grade into epibathyal calcareous marls (S2b) (Arenarie di Moransengo, Formazione di Termofourà) (d’A- tri, 1990a, b; d’Atri et al ., 1997; Piana et al ., 1997; d’Atri et al ., 2016b). In Torino Hill and western Monferrato, Burdigalian-lower Langhian mainly sandy resedimented deposits (S2a) (Pietra da Cantoni, Formazione di Visone, Membri di Rocca Crovaglia, di Ronchi e di C. Garino della Formazione di Costa Montada, Membro calcareo della Formazione di Montechiaro d'Acqui, Membro delle arenarie di C. Mazzurini della Formazione di Rocchetta- Monesiglio, Complesso Caotico del Monte Lisone, Formazione di San Paolo) are present (Dela Pierre et al., 2003b).

Unconformity D3 (late Burdigalian-early Langhian) In the southern part of BTP, it consists of a paraconformity developed at the base of the arenaceous-pelitic turbidite deposits of Synthem BTP 3. In the Monferrato and Torino Hill, it can be recognized as an angular unconformity between diﬀ erent types of platform deposits, which consist of prevalent carbonates in the lower part and mixed deposits in the upper part. The D3 onset is interpreted as related to the northward shifting of the BTP depocentres, due to the activation of the Monferrato thrust front (Falletti et al., 1995). Synthem BTP 3. In the southern part of BTP, it begins with Burdigalian- Langhian sandy-muddy turbidite successions (e.g., Serole, Cortemilia and Costa Areasa formations) with Langhian siliceous slope deposits at the top (Bistagno Formation) (S3a, S3b), followed by Langhian-Serravallian platform successions in the Alto Monferrato and Borbera-Grue (Marne di Cessole S3d, Arenarie di Serravalle S3f ) or slope to turbidite deposits in the Langhe (Marne di Cessole S3d; Cassinasco Formation, S3e). In the southern part of BTP, the Synthem locally ends with lower Tortonian hemipelagic sediments ( S3/4 ) (see also Ghibaudo et al ., 1985, 2010a, 2010b, 2014). In the northern part of BTP, Langhian siliciclastic shallow water deposits (Monferrato, Areniti di Tonengo) change laterally to a sandy and sandy-muddy deep-water succession (Torino Hill, Baldissero Formation), with which have been combined (S3d) in this report (Dela Pierre et al ., 2003a; Festa et al ., 2009; Rossi et al ., 2009). These are followed by Serravallian outer platform sediments (Marne di Mincengo, S3f).

Unconformity D4 (early Tortonian) In the northern BTP, the D4 corresponds to an angular unconformity placed at the base of slope deposits of the Synthem BTP 4. The hiatus associated to the D4 increases from west to east, reaching an Oligocene-lower Tortonian time gap. Geological Map of Piemonte Region at 1:250,000 scale 47

In the southern BTP, the D4 discontinuity only locally corresponds to an angular erosional unconformity at the base of lenticular ﬂ uvio-deltaic to intra- slope, and turbidite lenticular sandy and gravelly bodies. The D4 is ascribed to the onset of tectonic oversteepening of the northern and southern sectors of BTP toward the central areas, where a new conﬁ ned depocentre developed in a thrust-top basin bordered by the Torino Hill- Monferrato structural high associated with the Padane thrust front (Rossi et al ., 2009).

Synthem BTP 4. It starts with Tortonian-Messinian hemipelagic sediments (Marne di S. Agata Fossili, S3/4), containing lenticular bodies with an erosional base of sandy-gravelly resedimented deposits and chaotic sediments (S4a) (Clari & Ghibaudo, 1983; Ghibaudo et al ., 1985; Rossi et al ., 2009; d’Atri et al., 2016b). The Synthem 4 is closed by Messinian shallow water primary evaporites (Sturani & Sampò, 1973; Sturani, 1976), consisting of vertically stacked sele- nite gypsum-mudstone couplets (Vena del Gesso Formation, S4c), deposited during the ﬁ rst stage of the Messinian Salinity Crisis (hereafter MSC). They grade laterally into a coeval deeper euxinic succession (Membro di Nizza Monferrato, S4b; Irace et al., 2005; Dela Pierre et al., 2011).

Unconformity D5 (intra-Messinian) It corresponds to a sharp angular unconformity that cuts the primary evaporites of Synthem BTP 4 and marks the base of the reworked evaporites of the overlying Synthem BTP 5. Locally, it also cuts the underlying sediments down to the Tortonian (Irace et al ., 2005) and Oligocene. This surface is correlated to the Messinian Erosional Surface (Roveri et al ., 2003; Dela Pierre et al ., 2011), recognised at the Mediterranean margins and commonly related to an evaporation-related sea-level drop of at least 1500 m during the MSC acme, leading to subaerial exposure and erosion of marginal Mediterranean areas (e.g., Loﬁ et al ., 2011). An important phase of tectonic uplift induced the erosion and resedimentation of huge masses of marginal primary evaporites, the major accumulations of which are located in the central sectors of the basin, beyond the Padane thrust front (Irace et al., 2010).

Synthem BTP 5. It consists of upper Messinian (post-evaporitic) slope to basin resedimented evaporites (Complesso Caotico della Valle Versa, S5a; Fig. 12c), deposited during the second MSC stage (Dela Pierre et al ., 2002a; 2011). The genesis of these sediments, which mainly consist of chaotic deposits, was mainly related to gravity-driven phenomena, triggered by the intra-Messinian tectonic event. As a second hypothesis the concomitant contribution of shale diapirism and methane-rich ﬂ uid expulsion has been suggested (Clari et al ., 48 Fabrizio Piana et alii

1988, 1994, 2004, 2009; Irace et al ., 2005; Dela Pierre et al ., 2007; Cavagna et al., 2015).

Unconformity D6 (late Messinian) It corresponds to an erosional unconformity that locally reaches the Synthems BTP 3 and 4, and marks a sharp transition from deep-water evaporitic depositional systems to continental and coastal (non marine) systems that indicate important changes in the ﬂ uvial discharge and drainage pattern. The clear facies change and the subtle angular unconformity, observed along D6 on the basin margins, point to a tectonically-enhanced base-level fall and to the maximum basinward shift of the shoreline. Furthermore, the appearance of coarser-grained deposits and a concurrent change in the sediment composition across D6 indicate important modiﬁ cations in the drainage pattern and/or in the precipitation regime (Roveri et al., 2008).

Synthem BTP 6. It consists of upper Messinian (post-evaporitic) terrigenous continental and brackish water facies (Cassano Spinola Formation, S6a) deposited during the third, fi nal, MSC stage (Dela Pierre et al ., 2011). The Synthem BTP 6 is mainly exposed in the southern BTP, where sandstone with conglomerate and mudstone indicate the periodic activation and subsequent change from small fl uviodeltaic systems to non-marine basin conditions, as testifi ed by brackish-water ostracod and mollusc assemblages of the Lago Mare biofacies (Sturani, 1976). Toward the north (eastern Monferrato), they chan- ged to shelf sandstone and mudstone.

The Alpine foreland basin A foreland basin is that developing in front and parallel to a mountain belt as a consequence of the bending of the subducted lithosphere (lithospheric fl exure) induced by the immense rock-mass load, which followed the orogenic crustal thickening (Beaumont, 1981; Jordan & Flemings, 1991; De Celles, 2012). The Alpine foreland basin began to develop in the Eocene by the fi rst stages of Alpine collision (Crampton & Allen, 1995; Ford et al ., 1999). The subsequent lithospheric fl exure produced during middle Eocene-Rupelian an underfi lled basin ( sensu Covey, 1986) that is exposed only in the southwestern part of the Piemonte region (d’Atri et al., 2016a). In Piemonte, the Alpine Foreland Basin successions crop out only in the Maritime and Ligurian Alps, where they are overthrust by Lower Cretaceous- lower Paleocene Western Ligurian Flysch (Kerckhove, 1969; Piana et al ., 2014). The sedimentary succession of the Alpine foreland basin, unconformably resting on the Mesozoic successions of the palaeo-European margin Geological Map of Piemonte Region at 1:250,000 scale 49

(Briançonnais and Dauphinois units of the Maritime and Ligurian Alps), has been subdivided into two synthems bounded by regional-scale unconformities (Fig. 8).

Unconformity S4 (middle Eocene) It is an angular unconformity placed at the base of the Alpine foreland basin succession and corresponding to a latest Cretaceous-middle Eocene hiatus. It is the result of a period of subaerial exposure that led to the formation of palaeo-valleys fi lled with continental and lagoonal deposits, separated by interfl uvial areas. During the following transgression (e.g., Ford et al ., 1999; Varrone & Clari, 2003) this surface was reworked, in the interfl uvial sectors, by a ravinement surface. The S4 formed as the result of the inception of the Alpine foreland basin at the beginning of collisional Alpine tectonics.

Synthem AML 4. This synthem starts with discontinuous continental to lagoonal deposits (Microcodium Formation) followed by middle Eocene mixed carbonate-siliciclastic ramp deposits (Nummulitic Limestone), and by hemipelagic slope marls (Globigerina Marl).

Discontinuity surface S5 (late Eocene) It is a paraconformity at the base of the turbidite succession of Synthem AML 5 that ends the underﬁ lled stage of the Alpine foreland basin evolution. It corresponds to a sharp change in composition of sediment supply (from mainly carbonate to siliciclastic) due to the beginning of exhumation of the Alpine orogenic belt. Synthem AML 5. This synthem consists of a late Eocene to earliest Rupelian turbidite succession (Grès d’Annot), several hundred metres thick. The Geologic Units, originally deposited in the Alpine Foreland Basin and later aﬀ ected by low-grade metamorphism, have been labelled as AML 4m (Parasynthem AML 4m) and AML 5m (Parasynthem AML 5m) (Fig. 8). These units, which originated in the Alpine foreland basin, were later involved in the inner portion of the orogenic system and transformed by dissolution and recrystallization; in addition, these units were also deformed with partial shortening and transposition.

Units derived from the palaeo-European continental margin The units derived from the palaeo-European continental margin consists of polycyclic metamorphic basement 4 rocks and Mesozoic sedimentary

4 A «polycyclic metamorphic basement» is defi ned here as a bedrock consisting of an assem- 50 Fabrizio Piana et alii successions. These latter crop out as either wide continuous units, partially detached from their base, or minor patches scattered on the diff erent polycyclic units. In previous regional maps, the European palaeomargin units have often been reconstructed on the basis of their present structural position, their metamorphic features and debated palaeogeographic allocation (Sturani, 1973; Bigi et al ., 1990). In particular, geological units were referred to Mesozoic palaeogeographic domains such as the Dauphinois, Provençal, Briançonnais, Sub-Briançonnais, Ultra-Briançonnais, pre-Piemontese domains. However, it is worth to point out that in the geologic literature these domains have been referred to with diff erent meanings. Here, the terms Dauphinois, Provençal, Briançonnais, etc., are used according to their original meaning, i.e. , the sedimentary successions of the Cottian, Maritime and Ligurian Alps, deposited on diff erent palaeogeographic settings of the palaeo-European continental margin since the beginning of Jurassic. In fact, the Triassic palaeogeography started to be diff erentiated into distinct domains from the latest Triassic-Early Jurassic rifting stage ( F2a and F2b Geologic Events, see above). The older (Triassic, Permian and Late Carboniferous) sedimentary successions have been grouped into two regional-scale stratigraphic units (synthems and «parasynthems», see above and Fig. 8) labelled by acronyms consisting of two or three letters indicating the geographic area, the number of the discontinuity (see Table 1) and the related Geologic Event (e.g., SA0 , AC1 , AML 2 ). The tectonometamorphic units of the polycyclic basement (Dora-Maira, Ambin, Gran Paradiso, etc…) have been distinguished solely on the basis of their tectonic nature and/or geometric position, since these criteria have been deemed suffi cient to discriminate their distinctive features. A further distinction was made between the metamorphic and «non- metamorphic» sedimentary units (see above) since large portions of the Mesozoic-Cenozoic sedimentary succession are related to an external, relatively shallow, fold-and-thrust belt (Maritime and Ligurian Alps, Southalpine Domain of northern Piemonte), whereas another portion of the same succession was involved in the Alpine tectonic system and is presently scattered as minor patches on top of diff erent polycyclic metamorphic units.

blage of metamorphic rock complexes involved in more than one orogenic cycle. In this sense, a «metamorphic cycle» can consist of either a single metamorphic phase (monophase metamorphism) or several metamorphic phases (polyphase metamorphism) (Fettes & Desmons, 2007). Polycyclic metamorphic basements can contain not only polymetamorphic rocks, but also monometamorphic rocks, usually less abundant than the former ones. Geological Map of Piemonte Region at 1:250,000 scale 51

Sedimentary Units Permian and Triassic Units of the Piemonte Western Alps The Permian-Triassic sedimentary successions of the palaeo-European margin have been separated into two synthems bounded by discontinuity surfaces (S0, S1 and S2) correlated across several tectonic units (Fig. 8).

Unconformity S0 (Permian) It is a nonconformity that corresponds to the beginning of post-Variscan continental sedimentation.

Synthem AML 0. It consists of a Permian volcanic to volcaniclastic succession, mainly made up of ignimbritic rhyolites (AML 0 ).

Unconformity S1 (Early Triassic) It is an angular unconformity corresponding to a transgressive surface at the base of the Lower Triassic coastal quartzarenite succession. It represents the return to marine conditions on the Variscan belt.

Synthem AML 1. It consists of a Lower Triassic coastal quartzarenite succession (AML 1a ), followed by Middle-Upper Triassic peritidal carbonates and Upper Triassic lagoonal pelites and evaporites ( AML 1b ; Fig. 16). The AML 1a also includes the so-called «Alpine Verrucano» (Malaroda et al ., 1970) and the so-called «Permo-Eotrias» successions of the Alpine geologic literature (see Cassinis et al., 1979, for a review). The evaporites of AML 1b locally form hectometre-sized bodies associated with tectonic breccias, both in outcrop (e.g., Colle di Valcavera in the Stura di Demonte Valley; Fig. 10b) and in the subsurface (Colle di Tenda: Baldacci & Franchi, 1900; Cavinato et al., 2006).

Dauphinois, Provençal and Briançonnais sedimentary units These units crop out in the Maritime and Ligurian Alps (Sturani, 1962; 1963; Lanteaume, 1968; Vanossi, 1970; Vanossi et al ., 1994; Gidon, 1972; Malaroda et al ., 1970; Lanteaume et al ., 1990; Gosso et al ., 1983; Bertok et al ., 2012; Barale et al ., 2016a; 2017; d’Atri et al ., 2016a) and consist of Jurassic-Cretaceous mainly carbonate successions (Figs. 10a, d, 16) deposited in the palaeo-European passive margin of the Alpine Tethys. They are overlain by the middle Eocene–lower Oligocene Alpine foreland Basin succession. The Brianç onnais, Dauphinois and Provençal palaeogeographic domains5

5 The term «Sub-Briançonnais» was not used here, since, as suggested by Maury & Ricou 52 Fabrizio Piana et alii uccession uccession ) Triassic carbonates in the Monte Marguareis area d Briançonnais domain (Colle di Valcavera, between Briançonnais Stura domain (Colle di Valcavera, ) folded beds of Cretaceous limestones of the Dauphinois succession (left a ) gypsum along the tectonic contact between the Mesozoic carbonate s b ) migmatites of the Argentera Massif (ARG4 in the Map Legend); c (Synthem AML2) AML1) and AML0 (Synthem units of the and Triassic-Permian (Synthems the and Grana valleys); Fig. Fig. 10. Representative lithotypes of Maritime and Ligurian Alps: side side of Stura valley) (Synthem AML3 in the Map Legend); (Synthem AML1). (Synthem Geological Map of Piemonte Region 53 i Sampeyre, looking west. The Elva Valley is Valley Elva The west. looking i Sampeyre, onget Unit (ACC, quartzite and carbonate rocks of of rocks carbonate and quartzite (ACC, Unit onget va ridge (south-western Cottian Alps), from Colle d Colle from Alps), Cottian (south-western ridge va of the Liguria-Piemonte Oceanic Domain (OCc). Domain Oceanic Liguria-Piemonte the of dicates the tectonic contact between the Acceglio-L the between contact tectonic the dicates Fig. 11. Panoramic view of the Chersogno-Pelvo d’El Chersogno-Pelvo the of view Panoramic 11. Fig. visible below in the foreground. The dashed line in line dashed The foreground. the in below visible calc-schists the and AC3) and AC1 parasynthems the 54 Fabrizio Piana et alii ynthem BTP5), BTP5), ynthem ) peridotite (dunite) (OCp) of the Lanzo b ) folded metabasites (OCb in the Map Legend), consisting of a s: s: near Villardora (Torino); near Villardora (Torino); ) megablock of gypsum of the Complesso caotico della Valle Versa (CTV, S (CTV, Versa Valle della caotico Complesso the of gypsum of megablock ) c ) Pliocene sandstones (Sabbie di Ferrere, S8c) in southern Monferrato (Southern Pliocene Basin). Pliocene (Southern Monferrato southern S8c) in Ferrere, di (Sabbie sandstones ) Pliocene d Fig. Fig. 12. Representative lithotypes of the lower Susa valley and Monferrato hill alternating alternating layers rich in epidote and amphibole, respectively cropping out Banengo quarry (Asti); (Asti); quarry Banengo Ultramaﬁ c Massif (southern side of Monte Musinè); Musinè); Monte of side (southern Massif c Ultramaﬁ Geological Map of Piemonte Region 55

th (11 » ) mafi c mafi ) b Priorato Priorato Cluniacense « ) syenite from the Biella Pluton d ) orthogneiss from the Sesia-Lanzo Zone (SLO); (SLO); Zone Sesia-Lanzo the from orthogneiss ) a rvo valley utilized to build the walls of the , 2015, for further details): details): further for 2015, , et al. et ) andesite from the Biella volcano-sedimentary Suite (ANS); c , PCEs). » Sienite della Balma della Sienite « Fig. Fig. 13. Representative lithotypes of Biellese area: pebbles from the Ce century), Castelletto Cervo (Biella) (see Compagnoni (see (Biella) Cervo Castelletto century), granulite from the Ivrea-Verbano Zone (IVMg); granulite from the Ivrea-Verbano ( 56 Fabrizio Piana et alii , looking SE. The glacial deposits of the end Rivoli-Avigliana e in the background. Moncuni and M. Pietraborga highs are made of made are highs Pietraborga M. and Moncuni background. the in e Fig. Fig. 14. Landscape of the area Torino viewed from the outlet of the Susa valley visibl is Hill Torino the whereas foreground, the in evident is system moraine peridotite and serpentinite of the Lanzo Ultramafi Massif. c Ultramafi Lanzo of the serpentinite and peridotite Geological Map of Piemonte Region 57 longing to the Lanzo Ultramafi Massif. c Ultramafi Lanzo the to longing valley, consisting of meta-ophiolites and calc-schists of calc-schists and meta-ophiolites of consisting valley, traborga traborga (Trana), looking In NNW. the foreground the peri- i-Avigliana end i-Avigliana moraine system with lakes. Avigliana the In the Fig. Fig. 15. Landscape of the outlet of Sangone and Susa valleys viewed from M. Pie dotite of anked Moncuni by (OCp), the which glacial is deposits fl of the Rivol the Liguria-Piemonte Oceanic Domain; on the extreme right, the peridotites of M. Musiné be of M. Musiné peridotites the right, extreme on the Domain; Oceanic Liguria-Piemonte the background, the snowy peaks of the M. Rocciamelone-M. Civrari ridge, left side of Susa of side left ridge, Civrari Rocciamelone-M. M. the of peaks snowy the background, 58 Fabrizio Piana et alii . IBF: Internal Briançonnais » ophiolitic ophiolitic massif « so NNW. In the foreground the karst morphology of the pla- the of morphology karst the foreground the In NNW. (AML1b and AML2b) and the Permian-Triassic metasedimentary units units metasedimentary Permian-Triassic the and AML2b) and (AML1b Fig. 16. View of the Gardetta plateau from the northern side of Monte Giordano, looking looking Giordano, Monte of side northern the from plateau Gardetta the of View 16. Fig. ridge Cassorso M. of successions Triassic-Jurassic the centre the in teau, derived from the palaeo-European continental margin (MSC); in the background, the Monvi Front. Geological Map of Piemonte Region at 1:250,000 scale 59 were individualized during the Late Triassic-Middle Jurassic rifting in the newly forming European passive continental margin, which lasted up to Late Cretaceous times (Boillot et al., 1984; Lemoine et al., 1986). In the Maritime and Western Ligurian Alps (southern termination of the Western Alps arc), the structural setting can be depicted as a double-vergent tectonic system: the main NE-vergent transpressive fault systems to the north of the External Brianç onnais Front (Michard et al ., 2004; d’Atri et al ., 2016a) and the SW-vergent ones to its south. In this framework, the Dauphinois, Provençal and Briançonnais sedimentary units are arranged in a relatively complex setting that is the result of a branching of multiple tectonic contacts, corresponding to the Internal Briançonnais front zone (partially corresponding with the «Stura couloir» Auct .: Laubscher, 1971; Horrenberg et al ., 1978; Guillaume, 1980; Ricou, 1981; Ricou & Siddans, 1986; Giglia et al ., 1996), the Demonte-Aisone shear zone (d’Atri et al ., 2016a), the boundary faults of the NE border of the Argentera Massif, and the Limone–Viozene zone (Piana et al ., 2009). In the eastern Ligurian Alps, the Briançonnais successions are part of a S-SW-vergent thrust belt consisting of several thrust sheets detached from a polycyclic basement (Seno et al., 2005). The Jurassic-Cretaceous sedimentary successions of the palaeo-European margin have been subdivided into two synthems bounded by discontinuity surfaces (S2, S3 and S4) correlated in several tectonic units of the Maritime and Ligurian Alps (Fig. 8).

Unconformity S2 (Late Triassic-Early Jurassic) It is a disconformity corresponding either to a subaerial erosional surface (Briançonnais and Provençal) or to a submarine erosional surface (Dauphinois) with a Late Triassic-Early Jurassic or only Late Triassic hiatus. This discontinuity surface corresponds to the onset of continental rifting (F2a, Rift-onset unconformity). It was reworked in the rift high sectors (Briançonnais and Provençal) during the transgression, which is related to the opening of the Alpine Tethys oceanic basin and to the beginning of the spreading phase ( F2b, Tethyan breakup unconformity).

Synthem AML 2 . It consists of Middle Jurassic-lowermost Cretaceous platform limestone, locally aﬀ ected by intense hydrothermal dolomitization (Barale et al ., 2013, 2016b), and locally overlain by Lower Cretaceous open-marine condensed deposits in the Provençal domain ( AML2p );

(1983) and d’Atri et al . (2016a), in the Maritime-Ligurian Alps the «sub-briançonnais» units simply correspond to tectonic slices made up of Briançonnais, Provençal and Dauphinois units, presently arranged within regional-scale transpressive shear zones. 60 Fabrizio Piana et alii

Jurassic-Lower Cretaceous hemipelagic-pelagic limestone and marl, with carbonate breccia beds, in the Dauphinois domain (AML2d); Middle Jurassic restricted platform limestone and Upper Jurassic pelagic-plateau limestone in the Briançonnais domain (AML2b).

Unconformity S3 (Early Cretaceous) This unconformity is recognizable only in the Briançonnais domain, where it corresponds to a hardground and to an Early Cretaceous hiatus. In the Provençal domain, it corresponds to a drowning surface at the top of the Lower Cretaceous platform succession, whereas in the Dauphinois domain, characterized by a Jurassic-Lower Cretaceous deep-water succession, it changes to a correlatable conformity. Direct and indirect evidence of an Early Cretaceous transtensive tectonic event was described in diﬀ erent sectors of the European margin (Bertok et al ., 2012; Barale et al ., 2016b). Unconformity S3 can be ascribed to this transtensive tectonic event, which corresponds at a larger scale to the opening of the North Atlantic Ocean and the Bay of Biscay.

Synthem AML 3 . It consists of Aptian–Upper Cretaceous hemipelagic marls and marly limestones, locally with resedimented levels made up of siliciclastic grains and pebbles (Malaroda, 1963) or platform-derived bioclasts (Bersezio et al ., 2002) in the Dauphinois and Provençal domains (AML3d) and Upper Cretaceous hemipelagic marly limestones in the Briançonnais domain (AML3b).

Metasedimentary Units Metasedimentary units are here intended those geologic units consisting of sedimentary rocks whose primary features are totally to partially overprinted by a tectonometamorphic reworking with development of a new pervasive foliation and new mineral assemblages. In Piemonte, these types of units occur in the internal part of the Briançonnais domain in Maritime and Ligurian Alps, in the Acceglio-Longet Unit and in the upper Susa Valley, in the pre-Piemontese domain in the Grana and Maira valleys, and as scattered patches on the Ambin Massif and Dora- Maira Unit (Nappe system) The «metasedimentary successions» have been subdivided into «parasynthems» (see above, in the «Subdivision of Metasedimentary Units» section), which can be tentatively correlated with diﬀ erent tectonic units of the Piemonte Western Alps, on the basis of their primary lithologic, stratigraphic or chronostratigraphic characters (Fig. 8). The criteria used for separating the parasynthems are the recognition (or the inference) of the main unconformities of Table 1 (from S0 to S4). Geological Map of Piemonte Region at 1:250,000 scale 61

Late Carboniferous to Triassic metasedimentary units of the Maritime and Ligurian Alps Parasynthem AML 0. Permian metavolcanites (metarhyolite and subordinate meta-andesite, MSC 0 ; Fig. 16). Metarhyolites are largely exposed in the Piemontese Ligurian Alps from the Gesso to the Tanaro valleys, where they constitute the Monte Besimauda massif (whence the historical name of «besi- maudite»: Zaccagna, 1887). This parasynthem also comprises lower Permian metasediments (phyllite and micaschist rich in carbonaceous material, quartzite; ALI3 ) and Carboniferous metasediments rich in carbonaceous matter ( ALI5 ).

Parasynthem AML 1. Lower Triassic quartzite and metaconglomerate with stretched quartz pebbles (MSC 1a ), followed by Middle Triassic recrystallized dolostone and metapelite (MSC 1b).

Briançonnais metasedimentary units of the Maritime and Ligurian Alps The Briançonnais metasedimentary succession, cropping out in the Ligurian, Maritime and southern Cottian Alps (Malaroda et al ., 1970; Gidon, 1972; Sturani, 1973, 1975; Vanossi et al ., 1984; Michard et al ., 2004), has been subdivided into two «parasynthems».

Parasynthem AML 2. Middle-Upper Jurassic grey and pink marble, and recrystallized limestone (MSC 2). Parasynthem AML 3. Upper Cretaceous carbonate schists, locally containing intercalations of impure marble (MSC 3).

Briançonnais metasedimentary units of the upper Susa valley In the upper Susa Valley, a group of continental margin units (Re Magi, Vallonetto and Gad units in Polino et al ., 2002) is characterized by platform carbonates of Triassic age ( UMTm in Legend, ascribable to the AC1 parasynthem), followed by pink to white marbles locally containing breccia and ascribed to Late Jurassic (MSC 2), and by Cretaceous pelagic calc-schists (MSC 3). The supposed absence of Lower Jurassic deposits allows to ascribe these units to the Briançonnais domain of the Western Alps (see Lemoine & Tricart, 1986).

The «Acceglio-Longet Unit» This unit has been distinguished from the typical Briançonnais units due to its peculiar lithostratigraphic features (i.e., almost complete absence of Triassic and Jurassic carbonates above metamorphic basements rocks due the 62 Fabrizio Piana et alii pronounced Early Jurassic erosion) and its structural position in the Western Alpine belt: it corresponds to a NW-SE narrow belt cropping out from Col de Longet (NW) to the upper Maira Valley (SE) as a half-tectonic window in contact with various oceanic units of the Liguria-Piemonte zone and bounded to southwest by steep faults (Ceillac Fault system: Michard et al., 2004). This unit was restored in the Internal Briançonnais domain and reported as Ultrabriançonnais or Acceglio Zone (Debelmas & Lemoine, 1957; Lefèvre & Michard, 1976; Lefèvre, 1984; Michard et al ., 2004). The Acceglio-Longet Unit consists of diff erent tectonic subunits detached at diff erent stratigraphic levels (Acceglio-Rocca Corna and Pelvo d’Elva units in Piemonte: Gidon et al ., 1994). These subunits consist of monometamorphic volcaniclastics and minor polycyclic rocks (ACB, parasynthem AC0) occurring in the Pelvo d’Elva subunit (Monié, 1990), Triassic quartzite and «anagenite» (i.e., conglomerate with pink quartz and rhyolite pebbles) (ACC1, parasynthem AC1) (Fig. 11), thin platform carbonates of Triassic age and minor Jurassic carbonates (ACC2, parasynthem AC1) and Upper Cretaceous–Eocene (?) sediments (ACC3, parasynthem AC3) characterised by signifi cant amounts of chaotic breccias with reworked basement crystalline rocks, and Triassic and Jurassic carbonate blocks (Lemoine, 1967; Gidon et al., 1994).

Units derived from the polycyclic metamorphic basements and associated slivers of metasedimentary covers The lithotectonic units of the polycyclic metamorphic basement (labelled with their historical attributes such as «nappe», «nappe system», «fold-nappe», «massif») are described starting from the most external (Argentera) to the most internal and deeper one (Verampio nappe). See Fig. 9 for the geometric location of the lithotectonic units within the Alpine tectonic stack (or «nappe pile»).

Argentera «Massif» This unit corresponds to a massif elongated in a NW-SE direction for about 60 km along the French-Italian border and consists of a polycyclic basement extensively transformed to Variscan migmatite, still preserving abundant pre- anatectic relics. The Argentera Massif has been subdivided into two subunits: the Gesso-Stura-Vésubie and Tinée units, distinguished on the basis of lithological associations and metamorphic evolution (see Faure-Muret, 1955; Malaroda et al ., 1970; Malaroda, 1999; Compagnoni et al ., 2010 with references therein). The Gesso-Stura-Vésubie Unit consists mainly of metatexite and anatexite (Fettes & Desmons, 2007), anatectic leucogranite bodies up to few hundred- metre-wide (ARG 4, Fig.10c) and rare marble and metabasite ( ARG 3). A Geological Map of Piemonte Region at 1:250,000 scale 63

Permian (Ferrara & Malaroda, 1969) granitoid («Central Granite», ARG 5), intrusive into the migmatite, is also present, as well as a heterogeneous complex (Bousset-Valmasque complex: Faure-Muret, 1955; Rubatto et al ., 2001) made up of amphibole-bearing granitoid (ARG 6) crowded with inclusions (xenoliths?) of a wide range of lithologies with prevailing amphibolite ( ARG 2). Locally, remnants of high-pressure (HP) granulite with felsic (kyanite-K- feldspar-garnet gneiss) and maﬁ c composition (such as the Laghi del Frisson complex with eclogite layers) also occur (Ferrando et al ., 2008; Rubatto et al ., 2010; ARG 1). The Italian part of the Tinée Unit consists of Carboniferous migmatitic paragneiss (ARG 7) and minor amphibole-bearing migmatite (ARG 9). Between the Gesso-Stura-Vésubie and Tinée units, a major mylonitic Deformation Unit, the so-called «Ferriere-Mollières shear zone», hundred of metres thick and several kilometres long, occurs parallel to the NW-SE direction. It is composed of phyllonite derived from Carboniferous deformation of high-grade metamorphic rocks from the two adjacent Argentera subunits (Bogdanoﬀ , 1986; Musumeci & Colombo, 2002) ( ARG 8). This Deformation Unit seems to be sealed by Lower Triassic sediments (Faure-Muret, 1955; Sturani, 1962).

Ligurian Briançonnais Basement Units They consist of Paleozoic metamorphic basement units cropping out in the upper Tanaro Valley from Ormea to Ceva (e.g., Cortesogno et al ., 1981, 1993; Gaggero et al ., 2004). They are represented by Upper Ordovician ortho- and paragneiss (ALI 1), orthogneiss with metagranitoid relics ( ALI 4), and amphibolite-facies metabasite, with relict eclogite (ALI 2). The geometrical relations with the overlying Ligurian Briançonnais succession are mostly due to regional scale detachment surfaces.

Gran San Bernardo Units (Nappe system) The Gran San Bernardo composite nappe system is a tectonic assemblage consisting of several pre-Alpine polycyclic metamorphic units and Late Paleozoic monocyclic basement and metasedimentary cover units (for a ge- neral review and interpretation of this nappe system, occurring mostly out of Piemonte region, see Sartori et al., 2006; Scheiber et al., 2013). In the northernmost Piemonte, the Gran San Bernardo consists of a polycyclic unit known as «Siviez-Mischabel Nappe» (SBE) and the underlying «Pontis Nappe» (POb). The Siviez-Mischabel Nappe is made up of a Variscan metamorphic basement and a post-Variscan cover. The basement includes mainly paragneiss, schist and amphibolite (Stille & Oberhänsli, 1987; 64 Fabrizio Piana et alii

Gouff on & Burri, 1997). Slices of a Permo-Carboniferous metasedimentary sequence are locally preserved. In Piemonte, the Pontis Nappe consists of Triassic quartzite and marble. In the area between the Ossola Valley and the Sempione Pass, the Pontis Nappe corresponds to a part of the «Berisal Complex», whose rocks form the core of the famous Monte Leone overturned fold (see Steck et al., 2001; Pleuger et al., 2008, for a review). The Ambin Massif (Gran San Bernardo domain) It extends from the Arc Valley (in France) to the Susa Valley and consists of two diff erent geological units, the Clarea and the Ambin units in the lower and upper structural levels, respectively (e.g., Lorenzoni, 1963, 1965, 1968; Gay, 1972 a,b; Bertrand et al ., 2000). These units crop out in the core of a regional antiformal structure tectonically capped by several oceanic and carbonate units (Bigi et al., 1990; Polino et al., 2002). The Clarea Unit shows an exposed thickness of about fi ve hundred metres, but from drill cores it results to be at least fi fteen hundred metres thick. The main rock type of this unit is a micaschist ( AMC), greyish to bluish in colour with diff use veins and rods of quartz. The lowermost structural levels of this micaschist (AMCp) preserve metamorphic and structural features of at least two pre-Alpine events: a fi rst HP event recorded by quartz + garnet + rutile assemblages and a second medium- P amphibolite-facies event characterized by quartz + plagioclase + biotite + muscovite + garnet + staurolite + kyanite/ sillimanite paragenesis (Borghi et al ., 1999). Then, toward its upper structural levels, the micaschist of the Clarea Unit indicates a blueschist- to greenschist- facies Alpine tectono-metamorphic overprint (Borghi et al ., 1999; Malusà et al ., 2002; Polino et al ., 2002; Ganne et al ., 2003, 2004). Metre- to decametre- sized bodies of metabasite (AMCb) are associated with the micaschist. In these rocks a fi rst pre-Alpine assemblage is represented by rutile + epidote (zoisite) + garnet recording HP conditions; a second, and more pervasive, pre-Alpine metamorphic assemblage is represented by Ca-amphibole (hornblende) + oligoclase + epidote + biotite + titanite (in the absence of chlorite) developed under amphibolite-facies conditions (Borghi et al., 1999). Locally, masses of a grey orthogneiss with dioritic composition have been recognized, which preserves a pre-Alpine assemblage consisting of quartz + plagioclase + biotite + muscovite + garnet + rutile + epidote (Borghi et al ., 1999). The Ambin Unit is several hundred metres-thick. Two main pre-Triassic lithostratigraphic complexes can be recognized: the albite + chlorite Gneiss Complex (AMAg) and the Micaschist Complex ( AMAm). The former is a volcaniclastic sequence up to 100-200 m thick, consisting mainly of albite + chlorite gneiss with subordinate quartz-micaschist with alternating quartz + albite and white mica + chlorite levels, corresponding to an original Geological Map of Piemonte Region at 1:250,000 scale 65 compositional layering. Locally, as in the northern sector of the Ambin Massif, the micaschist contains graphite-bearing layers up to a few tens of metres thick and a few hundred metres long, and 10 to 40 cm-thick lenses of pre-Triassic marble. At several levels, clastic intercalations occur in form of both mm- to cm-size isolated pebbles and bodies of matrix-supported metaconglomerate. In addition, masses and lenses of metabasite (AMAb) are present in the lower structural levels. An Aplitic Gneiss (AMAi), up to a few hundred metres thick, intruded these complexes, as observed in the albite + chlorite Gneiss Complex at the confl uence between the Clarea Valley and the Susa Valley, and near Oulx. The Micaschist Complex locally contains thin (less than two metres thick) aplitic bodies. SHRIMP dating of magmatic zircons from the Aplitic Gneiss provides an age of 500 ± 8 Ma (U-Pb), resulting from an Early Paleozoic plutonic event (Bertrand et al ., 2000). The analysed zircons show an alkaline typology and do not exhibit evidence of a Variscan event (Bertrand et al ., 2000). Therefore, this would indicate an age younger than Late Cambrian for the albite + chlorite Gneiss and the Micaschist complexes. A Mesozoic succession unconformably rests on diff erent rocks of the Ambin Unit. Its lower unit is a metamorphic conglomeratic quartzite with pink quartz clasts, from mm- to cm-scale, of supposed Permian age and massive Lower Triassic quartzite ( AMMq, Parasynthem AC1). These silicate rocks are in turn overlain by successions (AMMc, Parasynthem AC1-AC3) of marble, variable amount of carbonate breccia and calc-schist ranging in age from Triassic to Cretaceous (Fudral et al ., 1994 a, b; Polino et al ., 2002 with references therein). The lack of pre-Alpine mineralogical assemblages in the Ambin Units would indicate the same polyphase blueschist- to greenschist-facies Alpine tectono-metamorphic evolution of the underlying Clarea Unit (Lorenzoni, 1965; Borghi et al., 1999; Malusà et al., 2002; Polino et al., 2002). The Clarea and Ambin units are separated by a tectonic contact (Barféty et al ., 1996) of pre-Alpine age (Gattiglio et al ., 2007; Mosca et al ., 2008), marked by a plurimetric-thick zone of phyllite and quartz-rich micaschist characterized by the same blueschist- to greenschist-facies Alpine assemblages of the two adjacent units (Gattiglio et al., 2007; Mosca et al., 2008).

Dora-Maira Units (Nappe) The Dora-Maira nappe is a composite lithotectonic unit made up of several metamorphic complexes consisting of pre-Triassic basement rocks and scattered Permian(?)-Mesozoic metasedimentary successions (Franchi, 1897; Franchi & Novarese, 1895; Vialon, 1966; Michard, 1967; Cadoppi & Tallone, 1992; Sandrone et al.,1993; Cadoppi et al., 1999). 66 Fabrizio Piana et alii

Continental units cropping out in the middle Maira Valley and in the lower Grana Valley (Pradleves) are referred here to the Dora-Maira nappe. The pre-Triassic basement rocks are represented by: - a polycyclic metamorphic complex of supposed pre-Carbonifeorus age (e.g., Sandrone et al ., 1993), consisting of garnet-chloritoid micaschist (DMS), metabasite (amphibolite and minor prasinite with relict eclogite) (DMSb), silicate marble (DMSm) and masses of granitoid and augengneiss (DMSo; «gneiss amygdalaires» of Vialon, 1966); - several sequences of monometamorphic basement rocks ( DMM) containing local lenses of metabasite (DMMb). In the central-southern sector of the Dora-Maira, micaschist, chloritoid-rich micaschist and quartzite have been grouped into the Dronero-Sampeyre complex (Vialon, 1966). The Dora-Maira also includes the monometamorphic Pinerolo Graphitic complex (DMG), classically correlated with Carboniferous units of the Western Alps (Franchi & Novarese, 1895; Sandrone et al ., 1993; Cadoppi et al ., 1999). This complex consists of micaschist, locally graphite-rich, and ﬁ ne-grained gneiss with intercalation of metaconglomerate and minor metabasite with early-Alpine epidote-blueschist-facies overprint. In the available geological maps, the graphitic Pinerolo complex is usually mapped as the lowermost structural level of the Dora-Maira composite unit; however, in the literature, this complex is also ascribed to the Briançonnais Units sensu stricto (e.g., Beltrando et al. 2010, and references therein). In this unit, eclogite remnants have never been found. - several late-Variscan meta-intrusives, from granitic to dioritic composition, occur, which are intrusive into both the polycyclic and monocyclic metamorphic rocks (e.g., Freidour, Borgone, Malanaggio, Pietra di Luserna gneisses in Sandrone et al ., 1993; Bussy & Cadoppi, 1996; Cadoppi et al ., 1999); - the «Brossasco-Isasca Unit», a metamorphic complex occurring in the southern sector of the Dora-Maira and representing the ﬁ rst documentat occurrence of ultra high pressure (UHP) metamorphism in continental crust (Chopin, 1984; Chopin et al ., 1991; Kienast et al ., 1991; Compagnoni & Hirajima, 2001; Compagnoni et al ., 2004; Groppo et al ., 2007; Compagnoni et al ., 2012). It consists of a Variscan amphibolite-facies metamorphic basement transformed to Alpine jadeite-garnet-kyanite-phengite micaschist with minor eclogite (DPB), and marble (DBPm). The Variscan rocks were intruded by Permian granitoids (Gebauer et al ., 1997), transformed during the Alpine orogeny into augen-gneiss and minor metagranite, and locally to metasomatic pyrope-coesite-bearing whiteschist (DBM) (Compagnoni & Hirajima, 2001; Ferrando et al., 2009). These pre-Triassic complexes are locally overlain by discontinuous and partly detached cover successions of Mesozoic age. The lower part of Geological Map of Piemonte Region at 1:250,000 scale 67 these successions consists of prevailing quartzite and conglomeratic quartzite (DM1a, Parasynthem AC1) considered to be Permian-Early Triassic in age, followed by marble and dolostone with local carbonate breccia (DM1b, Parasynthem AC1) generally Triassic-Jurassic in age. Then, the upper portions consist mostly of carbonate schists of Cretaceous age (DMC3, Parasynthem AC3), usually more phyllitic up-section and with local intercalations of siliciclastic sediments.

The Valosio Unit This unit, known as «Massiccio Cristallino di Valosio» (Chiesa et al ., 1975; Forcella et al ., 1973), is a pre-Alpine basement consisting of two main metamorphic complexes: a gneissic complex, consisting mainly of mylonitic orthogneiss and augengneiss, and a metapelitic-carbonatic complex, mainly consisting of micaschist, calc-schist and marble (Cabella et al ., 1991; Gaggero et al., 2004; d’Atri et al., 2016b). These two complexes may be assimilated, by lithologic analogy with the other polycyclic metamorphic basements (e.g., Gran Paradiso); the gneissic complex could correspond to the orthogneiss complex derived from late- to post-Variscan granitoids and the metapelitic carbonatic complex derived from a pre-granitic (Variscan or pre-Variscan) metamorphic basement. The rocks of both complexes locally include boudins of metabasics, with relics of pre-Alpine eclogite assemblages overprinted by greenschist-facies metamorphism (Messiga et al ., 2002). In the most sheared rocks along the contacts of the Valosio tectonic slices, carbonated fault rocks largely occur, due to hydrothermal activity during late faulting stages (Piana et al., 2006).

Gran Paradiso Unit (Nappe) The Gran Paradiso Unit (Nappe) is encompassing several valleys of both Piemonte and adjoining Aosta Valley regions. It is made of continental basement rocks cropping out in a large tectonic window within H P units of the Liguria-Piemonte Oceanic Domain (Argand, 1911, 1916; Michel, 1953; Elter, 1971; Compagnoni et al ., 1974; Compagnoni & Lombardo, 1974; Battiston et al ., 1987; Ballèvre, 1988; Bigi et al ., 1990; Le Bayon & Ballèvre, 2004; Gasco et al ., 2009; Gasco & Gattiglio, 2011). At a regional scale, the Gran Paradiso Unit rests over, or above, the Money Unit (Le Bayon et al ., 2006; Le Bayon & Ballèvre, 2006; Manzotti & Ballèvre, 2013, Manzotti et al ., 2014) a monocyclic unit, considered to be part of the Gran Paradiso Massif in the old literature. The Gran Paradiso Unit consists of two complexes: –the Gneiss Minuti (ﬁ ne-grained-gneiss) complex ( GPM), which represents the polycyclic Variscan basement, consists mainly of ﬁ ne-grained gneiss, 68 Fabrizio Piana et alii

and micaschist with boudins of partially retrogressed Alpine eclogites (Compagnoni & Prato,1969; Compagnoni & Lombardo, 1974) and very rare marble. –the Gneiss Occhiadini (augen gneiss) complex (GPO) (Compagnoni et al ., 1974) is mainly composed of augen gneiss derived from Permian (270 ± 5 Ma) porphyritic granitoids (Bertrand et al ., 2000; Ring et al ., 2005) intrusive into the Variscan metamorphic basement, i.e. the present GPM. On the left side of the Lago di Teleccio (upper Orco Valley), extensive relics of pre-Alpine intrusive structures are well preserved: Permian granitoids are intruding a sillimanite paragneiss, belonging to the Gneiss Minuti complex, overprinted by a Permian contact metamorphism and an Alpine eclogite- facies subduction metamorphism (Callegari et al ., 1969; Compagnoni & Prato, 1969; Gabudianu Radulescu et al., 2011).

Monte Rosa Unit (Nappe) The Monte Rosa nappe consists of the following pre-Alpine protoliths: (i) a basement composed of Variscan high-grade metamorphic rocks (MR1) intruded by a composite Late Paleozoic batholith with granite to granodiorite composition, dated to Carboniferous (310-330 Ma: Hunziker, 1970; Frey et al ., 1974; Engi et al ., 2001b) and to Permian (260-270 Ma: Lange et al ., 2000; Engi et al ., 2001b), largely transformed to orthogneiss/augengneiss (MR3) during the Alpine orogenesis; (ii) remnants of Permian-Mesozoic sedimentary sequences and the composite «Furgg Zone» (Bearth, 1952) (MR2). The polycyclic pre-granitic basement is composed of biotite-garnet-sillimanite paragneiss, micaschist, cordierite-bearing migmatite with metabasite and marble (Bearth, 1952, 1958; Dal Piaz, 1966, 1971, 2001; Engi et al ., 2001b), which did undergo Variscan high- T low- P metamorphism (Dal Piaz, 1971; Dal Piaz & Lombardo, 1986; Engi et al., 2001b).

The Furgg zone has been defi ned on the Swiss side of the Monte Rosa (Bearth, 1952) as a high-strain zone consisting of continental basement rocks (garnet-micaschist, paragneiss, gneiss derived from Permian granitoids and volcanic rocks), ophiolite (serpentinite, amphibolite, metagabbro) and Permian-Mesozoic sedimentary rocks (meta-arkose, metaconglomerate and quartzite) (Bearth, 1952; Froitzheim, 2001; Keller & Schmid, 2001; Liati et al ., 2001). For a few authors, this zone could represent the cover of the Monte Rosa or Portjengrat (Briançonnais according to Steck et al ., 2001) basement, whereas for others (Milnes et al ., 1981; Froitzheim, 2001) it is a tectonic mélan- ge. On the Italian side, the name Furgg zone was applied by Dal Piaz (1966, 1971, 2001), according to Bearth (1952), to a diff erent tectonometamorphic Geological Map of Piemonte Region at 1:250,000 scale 69 unit: i.e. a pre-Triassic complex of polycyclic micaschists with aplitic dykes and abundant intercalations of boudinated silicate marbles and lenses of metabasalts. It occurs at diff erent structural levels in the Anzasca, Gressoney and Ayas valleys. During the Alpine orogeny, the Monte Rosa nappe experienced a middle- Eocene HP metamorphic overprint (Rubatto et al ., 1998; Rubatto et al ., 1999; Pawlig, 2001; Pawlig & Baumgartner, 2001) under eclogite-facies conditions (Dal Piaz & Gatto, 1963; Dal Piaz, 1971; Chopin & Monié, 1984; Dal Piaz & Lombardo, 1986; Le Bayon et al ., 2006) and a late Eocene-early Oligocene (38-35 Ma) event from greenschist- to amphibolite-facies conditions (Bearth, 1958; Frey et al., 1974).

Camughera Unit and Moncucco-Orselina-Isorno Unit The Camughera-Moncucco basement unit, placed in the core of the Vanzone antiform (Bearth, 1956; Klein, 1978), can be subdivided into the Moncucco zone and the overlying Camughera zone, the two zones partly separated by a ductile shear zone marked by discontinuous slices of marble and quartzite of supposed Mesozoic age (Steck et al ., 1999, 2001, 2013, 2015), known as the «Salarioli-Mulde Zone» (Bearth, 1939, 1956). Both Camughera and Moncucco units comprise diff erent types of pre-Mesozoic paragneiss and orthogneiss (Keller et al ., 2005). The paragneiss is dominant in the Moncucco Unit, while the orthogneiss (CAM) prevails in the Camughera Unit. A Rb- Sr age determination obtained from orthogneiss of the Moncucco zone gave 271±4.8 Ma (Bigioggero et al ., 1981). In the paragneiss of both units, mafi c lenses occur and in the Moncucco Unit also a peridotite, which is partially transformed into talc-schist and serpentinite. In the Piemonte Geological Map, the Moncucco Unit has been grouped together with the Orselina-Isorno units, recently renamed «Bosco-Bombogno- Isorno-Orselina Unit» (Steck et al ., 2013). The Camughera Unit has been assigned to the Gran San Bernardo nappe system (Siviez-Mischabel nappe). The Moncucco Unit (assimilated by Bigioggero et al ., 1981 to the Gran San Bernardo nappe and by Steck et al ., 1979 to the lower part of the Monte Leone Unit) has been assigned, together with the Orselina-Isorno units, to more internal sectors of the palaeo-European margin (i.e. the classical Inner Penninic Domain). The Moncucco-Orselina-Isorno unit is composed of a polycyclic metamorphic basement including granite gneiss (MO1), serpentinized peridotite (MO2) and micaschists with minor calc-schist ( MO3). Trommsdorff (1990) and Engi et al . (2001a,b) interpreted these units as a «tectonic mélange », while Berger et al . (2005) assigned them to a Paleogene tectonic accretion channel. The Bosco-Bombogno-Isorno-Orselina Unit was aff ected by an Oligocene amphibolite-facies metamorphism (Steck et al., 2013). 70 Fabrizio Piana et alii

Lepontine Units (Nappe system) The Lepontine (Lower Penninic) nappe system encompasses the deepest nappes presently exposed in the Alpine belt. On the Italian side, it consists mainly, from top to bottom, of the Monte Leone, Lebendun, Antigorio and Verampio nappes (e.g., Castiglioni, 1958; Maxelon & Mancktelow, 2005; Berger & Mercolli, 2006; Dal Piaz, 2010; Steck et al., 2013 for a review). In Piemonte, the Lepontine Units are bounded to the south by the northward dipping, steep Canavese Line whose activity induced, during Oligocene times, a relative dextral movement and uplift (of 20 km at least) of the Lepontine nappe pile (Hurford, 1986; Merle et al ., 1989; Hunziker et al ., 1992). The upper amphibolite-facies metamorphic rocks of the Lepontine Units were then juxtaposed to the units of the Southern Alps, which did not experience the Alpine metamorphism. The Lepontine Units progressively steepen from north to south, so that near the Insubric Line they are subvertical. To the west, the Lepontine Units are bounded by the Simplon Fault, a southwestward dipping extensional shear zone showing a wide mylonite belt, overlain by cataclasite and dissected by more recent faults. The Simplon Fault (Mancktelow, 1985, 1992; Bistacchi et al ., 2001) was mainly active during Miocene and Pliocene, from 18 to 3 Ma (Hunziker et al ., 1992), and accompanied the dextral uplifting of the «Lepontine Dome» (e.g., Keller et al ., 2005). After being subjected to the Alpine high-P metamorphism, the Lepontine nappes were rapidly exhumed and the entire stack was overprinted by a dome-shaped metamorphism, referred to as the «Lepontine Metamorphism». The corresponding metamorphic isograds cut across the nappe boundaries: the highest metamorphic grade (sillimanite zone with partial melting) occurred just to the north of the Insubric Line (Brouwer et al ., 2004), whilst southward the metamorphic grade decreases rapidly. To the SW, the outcrop area of the Lepontine Nappes is «open», since the Simplon Fault does not merge into the Insubric Line, which turns to the northeast towards the centre of the Lepontine Dome, where it becomes progressively less distinct and then disappears. Consequently, the Moncucco and Camughera Units, and even the Monte Rosa Nappe are, in some way, continuous with the Lepontine Units system. The eastern boundary of the Lepontine Units (Forcola Fault in the Adula nappe: Meyre et al ., 1998) is placed outside the Piemonte region, in the Grisons area of Switzerland. For further details on the Gran San Bernardo, Monte Rosa, Camughera- Moncucco and Lepontine Units, see Steck et al. (2001), Froitzheim et al. (1996, 2008) for a review and visit the following web page: https://www. steinmann.uni-bonn.de/arbeitsgruppen/strukturgeologie/lehre/wissen-gratis/ geology-of-the-alps-part-2-the-penninic-nappes#section-3, «Geology of the Alps» by N. Froitzheim. Geological Map of Piemonte Region at 1:250,000 scale 71

Monte Leone Unit (Nappe). In the Isorno Valley (NE of Domodossola), the Monte Leone unit is composed of a tabular, fi ne- to medium-grained biotite–K-feldspar–oligoclase gneiss (Wieland, 1966; Burri et al ., 1994) derived from Permian granitoids (ML1). Minor masses of ultramafi te ( ML2, meta- peridotite and serpentinite of the Cervandone-Geisspfad complex: Gerlach, 1882) are also present in the upper part of the unit. The Monte Leone Unit depicts a spectacular overturned fold of kilometre scale, fi gured in Dal Piaz (2001). It is separated from the Bosco-Bombogno-Isorno-Orselina units by a sheet of Mesozoic calc-schist, garnet micaschist and marble (Jeanbourquin, 1994).

Lebendun Unit (Nappe). The Lebendun Unit is composed of metasedimentary rocks such as meta-arenite, metaconglomerate and micaschist («scisti bruni»: Burckhardt, 1942; Joos, 1969) originally deposited on the palaeo-European margin. The occurrence of blocks and pebbles of Triassic dolostone testiﬁ es to the post-Triassic, possibly Cretaceous age of these sediments (Rodgers & Bearth, 1960; Spring et al ., 1992). The Lebendun Unit is exposed over a large area to the north of the Antigorio Unit. Another slice of Lebendun (Permian?) metaconglomerate, up to 50 m thick, is exposed on the mountain ridge to the north of Pizzo di Bronzo in the upper Isorno Valley, between the Bosco zone on top and the Antigorio gneiss at the base. The Lebendun sequence consists of a pre-Triassic paragneiss core (Valgrande and Vannino gneiss, LB1), and a Mesozoic metasedimentary sequence presently in reversed position. The metasedimentary sequence indicates a continuous detrital sedimentation (Lebendun quartzite, LB2 ), derived from the erosion of a continental margin during the early rifting phase of the Alpine Tethys (Early Jurassic). The sedimentation continued until the Late Jurassic (Spring et al ., 1992) with the deposition of basinal, ﬁ ne-grained sediments, later transformed into calc-schist and micaschist (LB2).

Teggiolo Unit. The Teggiolo Unit ( TEG ) is deﬁ ned here as the Triassic to Lower Cretaceous sedimentary cover of the Antigorio and Verampio units. It is composed of Triassic quartzite, metapelite and dolostone, and Jurassic to Lower Cretaceous marble including pebbles derived from the underlying Antigorio granite and gneissic basement units, separated by erosional surfaces and large stratigraphic gaps (Spring et al ., 1992; Matasci et al ., 2011). The Teggiolo Unit is truncated at the top by tectonic discontinuities that are overlain by major masses of Upper Cretaceous to Eocene (?) terrigenous deposits referred to the Valais oceanic domain (see below). Antigorio Unit (Nappe). In the Antigorio (upper Toce) and Devero valleys the Antigorio Unit is a very thick (more than thousand metres: Klaper, 1990) 72 Fabrizio Piana et alii recumbent fold nappe (Gerlach, 1869,1871; Argand, 1911) composed of two types of orthogneiss ( GNE ), quarried as «Serizzo Antigorio», the darker biotite-rich and foliated one, and «Serizzo Formazza», the lighter leucocratic one, respectively. These orthogneisses derived from three main granitoid intrusions: (a) the 296 ± 2 Ma old Antigorio tonalite, (b) the dominant medium- to coarse- grained 290 ± 4 Ma old Antigorio granodiorite, and (c) the 289 ± 4 Ma old Antigorio granite (Bergomi et al ., 2007). Farther to the east, the Antigorio granitoids, intrusive into a polycyclic migmatitic basement and into the Paleozoic schists of the Baceno Unit, are also preserved in the Devero Valley and the Verampio window. The southeastern part of the Antigorio Unit is also known as «Pioda di Crana gneiss» (Steck et al ., 2013) and its protolith mainly consists of a 301 ± 4 Ma old granite (Bergomi et al ., 2007). Locally, micaschist and amphibolite are present throughout the unit.

Verampio Unit. The Verampio unit represents the deepest unit in the Alpine nappe stack, exposed in the window of the Toce Valley. A deep seismic study (Swiss National Foundation Project no. 20: Steck et al ., 1997; Steck, 2008) conﬁ rmed the thrust sheet geometry of the Verampio Unit (see also Meggiolaro et al ., 2011). The Verampio Unit, made up of a metagranite, is part of the larger «Verampio fold nappe» composed of the 291 ± 4 Ma old Verampio granite (U–Pb zircon age, Bussy, in Steck et al ., 2001) later transformed into the amphibolite-facies Verampio orthogneiss ( VER ), originally intrusive into Paleozoic (?) metagreywacke (Baceno schists, BAC ) and separated from the Antigorio fold nappe by a syncline of autochthonous Mesozoic metasediments (Castiglioni, 1958; Steck et al . ,1999, 2001, 2013; Dal Piaz, 2001).

Units derived from the palaeo-European continental distal margin In this section are gouped the Geological Units that are restorable, at the end of the rifting stage, at the transition zone ( sensu Hölker, 2001; Manatschal & Muntener, 2009) between the European passive continental margin and the external part of the Piemonte-Liguria Ocean. These units, well preserved in the Cottian Alps (Sturani, 1975; Lemoine et al ., 1986), have been described separa- tely from the other palaeo-European continental units. The Canavese zone has been included, in the literature (Ferrando et al ., 2004; Beltrando et al ., 2014, 2015a, 2015b, with references therein) in the palaeo-Adriatic continental distal margin. However, since their complex structural setting does not allow, at the current state of regional studies, a coherent mapping of the numerous tectonic slices, we considered it as an independent tectonic slice zone. Geological Map of Piemonte Region at 1:250,000 scale 73

Metasedimentary units of the Pre-Piemontese Zone (Auct.) These units, originally deposited in a physiographic domain facing the ocean, are characterised by Triassic platform dolostone, a signiﬁ cant occurrence of limestone and marble (resedimented slope deposits) of Early-Middle Jurassic age and Cretaceous calc-schist (hemipelagic sediments). Although the sedimentary evolution of these units is very complicated, they were restored along the thinned, distal European passive continental margin. In the geological literature, they were variably reported as Pre-Piedmont (e.g., Lemoine, 1971), Piedmont (e.g., Vanossi et al ., 1986; Polino & Dal Piaz, 1978) or Ultra- Piedmont units (e.g., Polino et al., 1983). These units, detached from their original pre-Triassic substratum, are extensively exposed in the region between the Maira and Grana valleys and in the Upper Susa Valley (Chaberton-Grand Hoche and Valfredda units in Polino et al ., 2002). Between the Thuras and Chisone valleys, these carbonate units form distinct morphological massifs, such as those exposed in the Grand Roc and Banchetta areas, where they are juxtaposed to small tectonic slices of Triassic quartzite ( UMSq), and gneiss and micaschist (UMSm). In addition, scattered fault-bounded bodies of dolostone, traditionally ascribed to the Middle-Late Triassic ( UMTz), are locally associated with continental crust units or occur within major tectonic zones where continental and oceanic units are presently juxtaposed. The Pre-Piemontese Units rest on platform dolostone ascribable to the Triassic parasynthem AC1, i.e., Middle Triassic dolostone ( UMTm) largely exposed in the Maira and Grana valleys, and Upper Triassic dolostone (UMTs) characteristic of the Mt. Chaberton region. In the Banchetta area, up-section, thin dolostone and black schist levels (UMR) alternating with calcareous schists have been dated to Rhaetian-Hettangian (Franchi, 1910; Michard, 1967; Polino et al., 1983). The Pre-Piemontese Units consist of prevailing carbonate schist with intercalation of carbonate breccia (UMG), dated to Early-Middle Jurassic (Franchi, 1897; Ellenberger et al ., 1964; Michard, 1967) and considered the result of extensional tectonics related to oceanic rifting. The upper part of these units consists of carbonate schist (UMGs, Late Jurassic to Early Cretaceous) with minor thin intercalations of quartzite (from former radiolarian chert?), followed upward by alternating carbonate schist, quartz-rich micaschist and phyllite with some intercalation of black shale (UMC, Cretaceous). These Jurassic-Cretaceous successions do not display signiﬁ cant occurrences of olistoliths and detrital levels of ophiolitic rocks. 74 Fabrizio Piana et alii

Units derived from the Liguria-Piemonte6 oceanic domain In Piemonte, ophiolitic units, derived from the Liguria-Piemonte Oceanic Domain, developed and spread between the palaeo-European and the palaeo- Adriatic margins during Jurassic and Early Cretaceous times (Bernoulli et al ., 1979; Bernoulli & Jenkins, 2009 with references therein). The Liguria-Piemonte Oceanic Domain was a part of the Western Alpine Tethys, which can be considered as an extension of the central Atlantic Ocean in the Tethyan realm (Dercourt et al ., 1986; Dal Piaz & Polino, 1989; Stampfl i et al ., 2002; Principi et al ., 2004). The oceanic peridotites, gabbros, basalts and the related volcano-sedimentary covers were involved in the orogenic processes at diff erent extents in the Alps and the Apennines, as indicated by the presence of: (i) units aff ected by regional metamorphism, mainly in the Alps, where they are classically named «Zona Piemontese», or «Zona Piemontese dei cal- cescisti con pietre verdi », «Zone des Schistes lustrés» representing the suture of the Mesozoic Western Tethyan ocean (Sturani, 1973, 1975; Dal Piaz, 1974, 1999; Bigi et al., 1990), (ii) units that largely escaped pervasive metamorphic overprint, such as in the Apennines and in parts of the Maritime-Ligurian Alps (Helminthoides Flysch: Sturani & Kerckhove, 1963; Kerckhove, 1969; Elter, 1973). The units aff ected by regional metamorphism were deeply subducted and accreted to the Adriatic active continental margin, whereas the latter were simply obducted over the Adriatic (Northern Apennines) or European continental crust (Maritime-Ligurian Alps).

«Non-metamorphic» units In the Piemonte map they are represented by the so-called «Helminthoides Flysch», also widely exposed in the Northern Apennines, out of the Piemonte region, and the Chenaillet Unit in the Cottian Alps.

The «Helminthoides Flysch» consists of Cretaceous varicoloured clays of the so-called «Basal Complex» followed by Upper Cretaceous-Paleogene mainly calcareous turbidite successions. In Piemonte, these units are referable to three diﬀ erent groups: ( i) Ligurian Units of the Monferrato, ( ii ) «Helminthoides Flysch» of the Northern Apennines, and ( iii) « Helminthoides Flysch» of the Maritime and Ligurian Alps.

6 With the purpose to homogeneize the very variable terminology used to deﬁ ne the meta- ophiolites of Piemonte and Liguria Western Alps and Apennines, labelled as Pie(d)montese- Ligurian Zone, Piemonte(se) Zone, Piemonte-Liguria Zone, etc., we have used the simplest geographic notation «Liguria-Piemonte» Oceanic Domain. Geological Map of Piemonte Region at 1:250,000 scale 75

(i) The Ligurian Units of Monferrato are represented by the «Formazione di Casale Monferrato» (CMO, Bonsignore et al ., 1969) consisting of interbedded marly limestones and clays, and the «Complesso Caotico di La Pietra», (CCP, Dela Pierre et al ., 2003) made up of blocks of diﬀ erent nature (mainly polygenic sandstone and conglomerate) included in a scaly clay matrix. These units are discontinuously exposed in the Torino Hill and Monferrato, where they represent the highly deformed Ligurian bedrock of the Tertiary Piemonte Basin succession (Cassano et al., 1986).

(ii ) The « Helminthoides Flysch» of the Northern Apennines crops out in the eastern sectors of the Tortona Apennines and Borbera Valley. It is represented by diﬀ erent lithostratigraphic units, all related to the «External» Ligurian subdomain («External Ligurids» of Elter, 1973) and exposed in two diﬀ erent tectonic units at the boundary between the Piemonte, Liguria and Emilia-Romagna regions. They are: - the Cassio unit (Marroni et al ., 2015) which consists of Upper Cretaceous varicoloured shale and arenite («Arenarie di Scabiazza») and the ophiolite-bearing shale and limestone of «Pietra di Parcellara» (LIf, Braga, 1965; Bellinzona et al ., 1971; Vercesi et al ., 2012), together with the Upper Cretaceous-lower Eocene? marly-carbonate turbidite successions of the Monte Cassio Flysch (LIe, Papani & Zanzucchi, 1969; Festa et al., 2014); - the Upper Cretaceous-Paleocene Antola Unit, which, in Piemonte region, comprises the pelitic-arenaceous successions of the «Argilliti di Pagliaro» (LIb, Boni et al ., 1969), the «Bruggi-Selvapiana Formation» (LId, Boni et al ., 1969; Bellinzona & Boni, 1971; Bellinzona et al ., 1971) and the «Monte Antola Formation» (LIc, Azzaroli & Cita, 1963; Abbate & Sagri, 1970), composed of hundred-metres thick, marly-calcareous turbidite. The only Ligurian units belonging to the «Internal» Ligurian subdomain («Interne Ligurids», Elter, 1973) exposed in Piemonte, are the Upper Cretaceous «Argilliti di Mignanego» consisting of arenaceous siltite with black shale and marly-calcareous turbidite sandstone (Marini, 1998; Ellero, 2000), cropping out to the east of the Sestri-Voltaggio Zone near Passo della Bocchetta.

(iii) The « Helminthoides Flysches» of Maritime and Ligurian Alps (Sturani & Kerckhove, 1963; Kerckhove, 1969; Rowan, 1990) are similar non-metamorphic Ligurian units (FLHa, FLHb) that extensively crop out to the northwest of the Argentera Massif (upper Stura Valley) and in the Western Ligurian Alps from Colle di Tenda to the upper Tanaro Valley. They overthrust the Ligurian Briançonnais successions and the Alpine foreland basin deposits 76 Fabrizio Piana et alii and consist of a «Basal Complex», known as San Bartolomeo Formation, made up of scaly clays. This complex often acted as tectonic detachment levels, of a thick turbidite succession made up of thickly bedded, coarse-grained sandstone in the lower part (Arenarie di Bordighera), and ﬁ ner-grained sandstone and limestone in the upper part (Flysch di San Remo-M. Saccarello). The whole succession was dated to the late Hauterivian–Maastrichtian interval (Giammarino et al ., 2010, and references therein). These units are intensively folded and sheared, but devoid of a signiﬁ cant metamorphic overprint (Bonazzi et al., 1987; Piana et al., 2014).

In the Cottian Alps, there are remnants of Ligurian units that largely escaped the eﬀ ects of the Alpine metamorphism. The ophiolitic Chenaillet unit was very weakly overprinted by the Alpine metamorphism, as indicated by crystallization of albite, prehnite, pumpellyite, Mg-riebeckite and epidote (Lewis & Snewing, 1980; Mével et al ., 1978). This unit rests directly on the oceanic Lago Nero Unit (Arata et al ., 1981; Arata, 1982; Polino et al ., 2002 with references), which is conversely characterised by Alpine HP mineral assemblages. The Chenaillet unit consists of variably serpentinized (OCHs) mantle rocks intruded by gabbro, diorite, dolerite, albitite (OCHg), and is overlain by a volcanic sequence of pillow basalt, pillow breccia and hyaloclastite (OCHb). A few metres thick sedimentary succession is preserved only locally and consists of conglomerate, graded sandstone and siltstone usually resting directly on top of the mantle rocks.

Metamorphic units Oceanic Units The stack of the oceanic units of the Western Alps consists of successions originated in the internal sector of the Liguria-Piemonte oceanic domain (Bigi et al ., 1990; Dal Piaz, 1974; Lagabrielle et al ., 1982; Deville et al ., 1992; Martin et al ., 1994). Traditionally included in the Penninic domain, these units have been variably distinguished in the literature on the basis of either their lithostratigraphic features or their tectono-metamorphic evolution. With the exception of the Chenaillet unit, all the oceanic units of the Western Alps display evidence of HP metamorphism (eclogite to blueschist facies conditions). In these oceanic units, the mantle-derived ultramaﬁ cs are mostly lherzolite, with minor harzburgite and dunite (OCp, Figs. 12b, 15) variably transformed into massive to foliated and mylonitic serpentinite (OCs). Locally, in the Geological Map of Piemonte Region at 1:250,000 scale 77

Upper Susa Valley, serpentinite bodies are covered by thin breccias interpreted as either sedimentary breccias with ophiolitic clasts in a calcite matrix, or ophicarbonate. Fe-Ti and Mg-Al metagabbros occur as dykes, mainly rodingitized, or small intrusive bodies (OCg). Masses and lenses of metabasalts (OCb, Fig. 12a), mainly derived from former pillow-lava of Normal-MORB affi nity, locally occur as prasinite. Basaltic dykes cut across ultramafi te, gabbro and rarely pillow-lava. These meta-ophiolites are overlain by a Jurassic to Cretaceous sedimentary cover, which starts with discontinuous levels of quartzite derived from former radiolarian chert, palaeontologically dated to Middle-Late Jurassic (De Wever & Caby, 1981; De Wever et al ., 1987; Cordey & Bailly, 2007) and marble of inferred Tithonian-earliest Cretaceous age ( OCr). Upward, a thick Cretaceous succession (OCc) of prevailing carbonate schist, micaschist and phyllite (derived from original marly sediments) extensively occurs such as in the Upper Susa Valley. These metasediments contain levels of olistoliths or clasts of ophiolites, siliciclastic rocks, carbonate breccias (OCm) and gneissic rocks (Polino, 1984; Lagabrielle & Polino, 1988; Lagabrielle et al ., 1989). These latter rocks, known in literature as the Charbonell gneiss, (OCx), are characterized by quartz, albite, white mica and porphyroclasts of K-feldspar with jadeite relicts (Pognante, 1980, 1983). In the Piemonte Map, all the scattered meta-ophiolites have been considered as derived from a single palaeogeographic domain (Alpine Tethys) (see Lombardo et al ., 1994 for a review). However, the historical names of main ophiolitic bodies (i.e., the so called «ophiolitic massifs») of Monviso (Fiora et al ., 1978; Lombardo et al ., 1978; Castelli et al ., 2014; Fig. 16), Voltri and Palmaro-Caff arella Units (Chiesa et al ., 1975; Forcellla, 1976; Piccardo, 1984; Messiga & Scambelluri, 1991; Scambelluri et al ., 1991; Capponi et al ., 1994; Desmons et al. 1999; Capponi & Crispini, 2002, 2009), Lanzo (Nicolas, 1966; 1967; Elter et al ., 2005; Piccardo, 2010) and Orsiera-Rocciavrè (Pognante, 1979 b) have been reported in the Map Legend. These «ophiolitic massifs», which do not form a continuous belt, but are scattered at diff erent structural levels of the Western and Ligurian Alps, show partially diff erent oceanic alteration and/or Alpine tectono-metamorphic evolutions (Bertrand et al ., 1982; Polino & Lemoine, 1984; Martin et al., 1994). Antrona Unit The so-called «Antrona Zone», «Antrona-Mulde» (Bearth, 1954), or «Antrona ophiolite» zone (Colombi & Pfeifer, 1986; Pfeifer et al ., 1989; Turco & Tartarotti, 2006) is also included in the Liguria-Piemonte Oceanic domain (Bigi et al ., 1990; Steck et al ., 2015). This oceanic unit, which crops out in the 78 Fabrizio Piana et alii

Ossola region (namely in the Antrona, Loranco, Anzasca and Vigezzo valleys) is presently placed within the Alpine orogenic belt in a lower geometrical position with respect to the other Liguria-Piemonte units. The Antrona meta-ophiolite separates the overturned limb of the Monte Rosa nappe from the Camughera-Moncucco-Orselina-Isorno Unit. It consists of serpentinite, metabasalt, and metagabbro with eclogite relics (Colombi & Pfeifer, 1986), and their former sedimentary cover, now calc-schist, micaschist, marble and quartzite. As for many other units derived from the Liguria-Piemonte oceanic domain, the Antrona meta-ophiolite may be regar- ded as a fossilized fragment of oceanic lithosphere, including mantle rocks, volcanics and deep-sea sediments (Tartarotti et al., 2011).

Units derived from the Valais domain The Valais domain, which in Piemonte crops out only in a relatively small area of the upper Toce Valley, is interpreted as a minor oceanic domain developed since Early Cretaceous in a more external (northern) position with respect to the Liguria-Piemonte basin (Trümpy, 1955; Frisch, 1979; Stampﬂ i et al., 1998; Schmid et al., 2004; Liati et al., 2005; Handy et al., 2010). A sequence of Valais calc-schist is exposed to the north of the Lebendun nappe, west of the Toce Valley in the Alpe Veglia and Devero Natural Park, and in the Lago del Sabbione areas. The calc-schist derives mainly from Cretaceous and Paleogene (?) sediments of the Valais basin ( VA4 ). This age was inferred by comparison with the siliceous schists of the Sion–Courmayeur zone, correlatable with the Piemonte Valais calc-schist, dated at 40-35 Ma (Bagnoud et al ., 1998). The calc-schist includes minor tabular bodies of amphibolite and prasinite most likely derived from original basalts (VA3 ). The metasediments related to the Valais domain rest on top of discontinuous levels of marble and recrystallized limestone of inferred Late Triassic-Jurassic age, labelled in the map as VA2, and minor levels of Lower Triassic quartzite ( VA1 ).

Units derived from the palaeo-Adriatic continental margin In the Piemonte region, huge parts of the palaeo-Adriatic margin formed two ﬁ rst-order geologic units: The Austroalpine Domain and the Southalpine Domain that are here considered as two main Lithotectonic Units.

The Austroalpine domain Formerly deﬁ ned (Argand, 1909, 1911) as the « Upper Penninic (VI) Dent Blanche nappe » together with its «root zone» (Sesia-Lanzo Zone), these tectonometamorphic units have been referred (Dal Piaz et al ., 1972) to the Geological Map of Piemonte Region at 1:250,000 scale 79

Austroalpine domain of the Western Alps, considered as either fragments of the former continental margin of the Adriatic (Apulian) plate or extensional allochthons (Dal Piaz, 1999; Beltrando et al ., 2014). These coherent crustal fragments consist of polycyclic and monocyclic crystalline basement and a few Mesozoic metasedimentary cover units. In the Piemonte Map, the Austroalpine Domain consists of the Sesia-Lanzo Zone (Dal Piaz et al ., 1972), including the «Second Diorite-kinzigite Zone» (II nd DK) (Carraro et al ., 1970; Dal Piaz et al ., 1971). Sesia-Lanzo Zone The Sesia-Lanzo Zone is the innermost unit of the axial sector of the Western Alps, bounded to the east by the Canavese zone and related tectonic Line, and to the NW by tectonic contacts against the underlying oceanic units of the Combin Zone of the Liguria-Piemonte Domain. It is a composite nappe consisting of three main units, which are diﬀ erent in both lithology (predomi- nantly Paleozoic continental rocks) and metamorphic features (Dal Piaz et al ., 1972; Compagnoni et al ., 1977). According to the classic nomenclature (see overview in Compagnoni et al., 2014), these units are:

– the «Second Diorite-kinzigite Zone» (IIDK, II nd DK, 2 nd DK, Novarese, 1929, 1931; Carraro et al., 1970) is the uppermost tectonic element of the Sesia Lanzo Unit. It consists of tectonic sheets of pre-Alpine granulite- to amphibolite-facies felsic, maﬁ c and carbonate rocks, similar to those of the Ivrea-Verbano zone (Dal Piaz et al ., 1971; Minnigh, 1977; Ridley, 1989; Babist et al ., 2006) and only partially transformed by the Alpine metamorphism.The more abundant and peculiar lithotype of the IIDK is a sillimanite-garnet-biotite paragneiss with metatects («kinzigite») (SDKk) with amphibolite (SDKd, corresponding to the «diorite» of the old geological literature), marble and mantle peridotite (in the Artogna Valley: Dal Piaz et al., 1971; Beccaluva et al., 1979). – the «Gneiss Minuti» (= «ﬁ ne-grained gneiss») Complex : it is located in the external part of the Sesia-Lanzo Zone and consists mainly of orthogneiss (SLG) and minor metagabbro bodies (Mount Pinter, in the Aosta Valley region) of probable Permian age (Dal Piaz et al ., 1971; Dal Piaz, 1992) (SLGm). The orthogneiss appears to have derived from granitoid of probable Permian age (cf. Dal Piaz et al ., 1972; Compagnoni et al ., 1977). However, the Gneiss Minuti Complex does not have clear relicts of pre-Alpine metamorphism and shows a pervasive Alpine metamorphic greenschist-facies overprint with blueschist facies relicts (Dal Piaz et al ., 1971; Pognante, 1989; Lardeaux & Spalla, 1990); – the «Eclogitic Micaschists» Complex consists of a polycyclic basement 80 Fabrizio Piana et alii

intruded by Permian granitoids showing a dominant Alpine imprint under Late Cretaceous eclogite-facies conditions (Dal Piaz et al ., 1972; Compagnoni & Maff eo, 1973; Hunziker, 1974; Compagnoni, 1977; Compagnoni et al ., 1977; Pognante, 1979a; Pognante et al ., 1987; Rubatto et al ., 1999). The basement is mainly made up of omphacite-garnet- phengite paragneiss («eclogitic micaschist»), and Permian (Oberhänsli et al ., 1985; Paquette et al ., 1989) metagranitoids (SLO, Fig. 13a) such as the jadeite-bearing metagranite of the Monte Mucrone (near Biella) (Compagnoni e Maff eo, 1973), minor metamafi te (mainly eclogite) ( SLE), ultramafi te (Pognante, 1979a; Ferraris & Compagnoni, 2003) and relics of pre-Triassic impure marble (SLEm). This complex, which is characterized by peculiar eclogite-facies minerals (garnet, jadeite, omphacite, glaucophane, zoisite, Mg-chloritoid, white micas, rutile), can be considered the best example of subducted continental crust recrystallised under quartz- eclogite-facies conditions and rapidly exhumed. – a thin sedimentary cover (of inferred Mesozoic age) of the «Eclogitic Micaschists» Complex, consisting of monometamorphic paragneiss, carbonate schist and locally manganiferous impure quartzite, has been locally recognized in the central part of the Complex (Venturini, 1995; Venturini et al ., 1994; 1996; Compagnoni et al ., 2014). Furthermore, in the southwestern part of the Complex (e.g., Monastero and Corio Canavese regions), Permian continental metagabbroids occur (SLEg), which are intrusive into the polycyclic metamorphic basement (Dal Piaz et al ., 1971; Bussy et al ., 1998; Rebay & Spalla, 2001); – the Rocca Canavese Unit is located in the southeastern sector of the Sesia-Lanzo Zone, between the «Eclogitic Micaschists» Complex and the Canavese Zone. This unit consists of several thin slices of heterogeneous continental crust with widespread lawsonite blueschist-facies metamorphic overprint (SLR) alternating with antigorite serpentinite ( SLRs), separated by mylonite and omphacitite reaction rims of Alpine age (Pognante, 1989a; Spalla & Zulbati, 2003; Zucali et al., 2012).

The Southalpine domain (Southern Alps) This domain is the portion of the Adriatic continental margin that remained at shallow depth during the Alpine orogeny, having been only gently back- thrust toward the Padane-Adriatic foreland of the Alps. From the Neogene, the Southalpine thrust-and-fold belt grew and progressively propagated towards the Padane-Adriatic foreland, reactivating extensional Mesozoic faults (Polino et al ., 1990; Castellarin et al., 1992, 1993; Cuﬀ aro et al., 2010 with references therein). Its tectonic front is mainly buried beneath the alluvial deposits of the Po Plain and sealed by upper Pliocene to Quaternary deposits. Geological Map of Piemonte Region at 1:250,000 scale 81

To the northwest, the Southern Alps are bounded by the Canavese Line, previously discussed, i.e ., the southwesternmost segment of the Periadriatic fault system. The basement rocks of the Southalpine Domain in the area of the map, unconformably covered by Permian to Jurassic sediments (i.e., the «Southern Alps» sedimentary succession), consist of Variscan and pre-Variscan granulite-amphibolite facies metamorphic rocks derived from sedimentary, felsic and mafi c igneous protoliths. This metamorphic basement was intruded by granitoids and gabbros of Permian age (D’Amico & Mottana, 1976; Boriani et al ., 1992) and covered by volcanic and volcaniclastic deposits. The western part of the Southalpine basement is known as «Massiccio dei Laghi» (sensu Boriani et al ., 1990). It extends from southern Switzerland to the Biella region, and includes the Ivrea-Verbano Zone and the nearby «Serie dei Laghi» metamorphic complex (see also Handy et al ., 1999). A recent interpretation considers the mafi cs of the Ivrea-Verbano Zone (known as «Ivrea Mafi c Complex), together with the granitoid and rhyolite of the Serie dei Laghi, as a single complex of Permian age named «Sesia Magmatic System». These mafi c and felsic igneous bodies are thought to be representative of the lower and upper crust, respectively: as a consequence of a later tilting, this complete section of the Adriatic crust is now exposed (Boriani et al ., 1974; Sinigoi et al ., 2010, see below).

Triassic to Jurassic Southalpine sedimentary successions These sediments represent the cover of the «Southalpine» basement and belong to the so-called «Southern Alps» sedimentary succession, mainly Mesozoic in age. This succession extends on west-east direction from northeastern Piemonte (Piemonte Lakes district) to the Eastern Alps, as well as in the subsurface as far as the Ferrara region (Pieri & Groppi, 1981; Bernoulli et al ., 1990). A small portion of the «Southalpine» sedimentary succession, mainly made up of Triassic and Jurassic sediments, crops out also in eastern Piemonte (e.g., Sostegno, Monte Fenera, Gozzano and Arona: Rasetti, 1897; Carraro & Sturani, 1972; Govi, 1977; Berra et al ., 2009). This succession has been subdivided into two synthems, bounded at the base by the S1 and S2 discontinuity surfaces, respectively. Synthem SA1: it consists mainly of Middle Triassic peritidal dolostone, locally preceeded by a few metres of shallow-water sandstone, which displays a gentle discordance with respect to the underlying volcaniclastic deposits. Synthem SA2: it consists of a thin layer of dolomitic breccia (attributed to the latest Triassic-earliest Jurassic), followed by Lower Jurassic shallow- marine sandstone and open-marine marly limestone. 82 Fabrizio Piana et alii

Massiccio dei Laghi Permian magmatic complex. In the last two decades, this magmatic complex has been studied by several research groups (see Quick et al ., 2009 with references therein), who demonstrated that its emplacement was coeval (Permian) and genetically related to that of the Ivrea-Verbano «Mafi c Complex». This igneous complex consists of felsic volcanics, including extensive caldera deposits, and felsic plutons that intruded into the upper crust of the «Serie dei Laghi». In this interpretation, the magmatic complex Permian, recently named «Sesia Magmatic System» (Mazzucchelli et al ., 2014), was intruded, as a whole, into both the metamorphic rocks of Serie dei Laghi and the Kinzigitic Complex of the Ivrea-Verbano Zone. However, in the Piemonte Geological Map, the Permian magmatic complex and the Mafi c Complex of the Ivrea-Verbano Zone have been shown as two distinct, fi rst-order, geologic units, since the available geologic maps (Geological Map of Italy, Varallo sheet, 1927; Bigi et al., 1990) are based on the previous classical interpretation. – Quartz-porphyry Complex (Complesso dei porfi di quarziferi) (POQ). It mainly consists of rhyolitic ignimbrite and rhyolitic tuff and breccia, and minor basal dacite interpreted as being the volcanic counterpart of the coeval «Graniti dei Laghi» complex (Kuenen, 1925; Fritz & Govi, 1963; Govi, 1977; Stille & Bulletti, 1987; Mazzucchelli et al ., 2014). These volcanics, dated at about 280-270 Ma, were interpreted as related to the activity of a very large, km-scale caldera whose minimum diameter was about 13 kilometres, fed by a middle- to deep-crustal plutonic magmatic system extended to a depth of about 25 km (Mazzucchelli et al., 2014). – «Graniti dei Laghi» Complex (GLA). This Complex includes the «Biellese and Valsessera Granite» (Balconi, 1963; Balconi & Zezza, 1965; Zezza, 1977; Geol. Map of Italy, Sheet 43 Biella, 2 nd Ed., 1966), the granitic bodies of Alzo, Roccapietra and Quarna (Burlini & Caironi, 2008), recently renamed as «Valle Mosso and Rocca Pietra Granite» (Mazzucchelli et al ., 2014), and the granite to granodiorite suite of Montorfano, Baveno- Mottarone and Mergozzo (Zingg, 1983). These granitoid bodies (see, for a more detailed map: Boriani et al ., 1988) are the result of an early Permian magmatic event intrusive into the «Serie dei Laghi» complex that is coeval (288 to 278 Ma: Quick et al ., 2009) with the above described volcanic suite.

«Serie dei Laghi» Complex. The «Serie dei Laghi» metamorphic complex, consisting mainly of amphibolite-facies metasediment and metagranitoid, is considered, together with the adjoining Ivrea-Verbano Zone (see below) as an almost complete, ideal, section through the pre-Alpine crust Geological Map of Piemonte Region at 1:250,000 scale 83 of northwest Italy (Borghi, 1989; Boriani et al ., 1990). This complex includes the Paleozoic «Scisti dei Laghi» Unit and the «Strona-Ceneri Zone», a Proterozoic to Paleozoic second-order geologic unit. The western boundary of the «Serie dei Laghi» is marked by the Cossato-Mergozzo-Brissago shear zone and by the Pogallo fault system (Boriani & Sacchi, 1973; 1985; Handy, 1987; Boriani et al., 1990). – «Scisti dei Laghi» Unit. The Scisti dei Laghi Unit (LAM) consists pre- dominantly of amphibolite-facies micaschist and paragneiss locally re-equilibrated under greenschist-facies conditions (Boriani et al ., 1977) probably during the Variscan orogeny. The «Scisti dei Laghi» rocks are the polycyclic metamorphic product of pelitic-arenaceous sediments of unknown age. Along the boundary with the Strona-Ceneri Zone, orthogneiss with Ordovician protolith (LAO) is also present, which represents the metamorphic product of original granitoids emplaced at approximately 450 Ma ago (Boriani et al., 1982). – Strona-Ceneri Zone. The rocks of the Strona-Ceneri Zone (for a more detailed map, see Boriani & Burlini, 1995) are the amphibolite-facies metamorphic product of an original arenaceous and clay-rich sedimentary succession; they include the metasandstone of «Ceneri gneiss», (SCG) and clay-rich metasiltite and metasandstone of the «Gneiss minuti» (SCGs, Baechlin, 1937; Boriani et al ., 1977). Major amphibolite bodies (SCGa), mostly derived from basaltic tuﬃ te, with serpentinite and minor metagabbro, extensively occur in the lower portion of the unit (Boriani & Giobbi Mancini, 1972; Boriani et al., 1990). The age of the Strona-Ceneri protoliths spans from the Neoproterozoic to the Early Paleozoic (700-500 Ma, Hunziker & Zingg, 1980; Boriani et al ., 1990; Zingg et al., 1990; Schmid, 1993).

Ivrea-Verbano Zone. This major geologic unit, a magmatic-metamorphic complex, is very famous among geologists and was intensively studied since the beginning of the past century (Artini & Melzi, 1900; Boriani & Sacchi, 1973; Boriani et al 1974; Menhert, 1975; Fountain, 1976). It represents an exposed section of the lower crust, formerly delaminated, thermally perturbed and then accreted by mantle-derived magmatic bodies (Rivalenti et al ., 1981; Rutter et al ., 1993; 1999; Quick et al ., 1995; 2003). The Ivrea-Verbano Zone (IVZ) is one of the few well-preserved examples in the world showing the so called «magmatic underplating», i.e., the magmatic process generating a new lower crust under extensional, high temperature (H T) conditions, when portions of metamorphic rocks, detached from the continental crust, reacted with maﬁ c magmas derived from the partial melting of the upper mantle. In the IVZ, this process occurred in the early Permian (Quick et al ., 2009). 84 Fabrizio Piana et alii

During the Alpine orogeny, the IVZ was uplifted, exhumed and tilted along an axis roughly parallel to the Canavese Line, so exposing the deeper part of the Adriatic crust. The contact with the «Serie dei Laghi» complex is marked by an inferred Permian HT mylonite, known as the Cossato-Mergozzo-Brissago Line (Boriani & Sacchi, 1973; Zingg, 1983; Handy, 1987; Boriani et al ., 1990). In the Piemonte Geological Map, the IVZ has been subdivided into three main second-order metamorphic and magmatic complexes: i) the Kinzigite Unit (representing the host basement rocks), ii ) the Permian «Mafi c Complex» (represented by layered gabbro bodies) and iii) the «Finero Sequence», which includes the Triassic «Finero Mafi c Complex». – The Kinzigite Unit (Novarese, 1931; Bertolani, 1954, 1958, 1960; Zingg, 1983; Boriani et al ., 1974; Sills & Tarney, 1984) consists of an amphibolite- to granulite-facies metamorphic sequence of sillimanite- and garnet-rich paragneiss, known as «kinzigite» (IVK), in the SW part, and quartz/feldspar-rich paragneiss, known as «stronalite» (named after the Strona Valley; Artini & Melzi, 1900; IVKs), in the NE portion. Migmatite (IVKm), marble (IVKr), amphibolite (IVKa) and HP- granulite also occur. – The Permian Mafi c complex (Rivalenti et al ., 1975, 1981, 1984) is a large composite body of mostly gabbroic composition (IVMg, Fig. 13b) with subordinate diorite (IVMd), tonalite, granodiorite, charnockite (IVMc) and cumulus ultramafi cs. These rocks are interleaved with slices of the country kinzigite unit. The Mafi c complex also includes several bodies of mantle- derived peridotite and related serpentinite (IVMa, IVMp) (Rivalenti & Mazzucchelli, 2000), the largest and best studied being the Baldissero and Balmuccia bodies. These mantle peridotite slices are aligned along the northwestern margin of the complex, which corresponds to the deepest stratigraphic part of the IVZ. Tens of other minor lithospheric mantle peridotite bodies also occur throughout the IVZ at various stratigraphic levels (Lensch, 1968, 1971; Marchesi et al ., 1992; Mazzucchelli et al ., 1992; Barbieri, 1996; Mazzucchelli et al., 2014). – The « Finero Sequence» (Siena & Coltorti, 1989; Mazzucchelli et al ., 2014) is exposed in the northeastern part of the IVZ, from the Vigezzo-Centovalli valleys to the Cannobina Valley. The IVZ includes the Finero mantle ultramafi cs (strongly metasomatised harzburgite), exposed in a pseudo-antiform and fl anked by the Finero Mafi c Complex . The Early Triassic radiometric age of the Finero Mafi c Complex (Zanetti et al ., 2013; 2014) is debated, because it is in contrast with the Permian age of all mafi c and felsic igneous bodies throughout the Austroalpine-Southalpine domain. The existence of a marked positive gravity anomaly below the IVZ (known as the geophysical «Ivrea Body») (Ogniben et al ., 1990; Kissling, 1984; Zingg et al ., 1990) Geological Map of Piemonte Region at 1:250,000 scale 85

documents the occurrence at depth of a high-density mantle body near the internal boundary of the axial part of the Alpine orogenic belt. The present exposure of the IVZ is the result of the combined eﬀ ects of vertical uplift due to Mesozoic crustal thinning and lithospheric wedging related to the Alpine collision (Schmid et al ., 1987; Nicolas et al ., 1990; Polino et al ., 1990).

Tectonic slice zones Heterogeneous tectonic slice zones have been defi ned in the geological Map of Piemonte. A «tectonic slice zone» is here intended as a large geological domain (some hundreds square kilometres wide) characterized by the presence of tectonic slices of diff erent size (in some cases too small to be mapped as independent units), referable either to diff erent geological or palaeogeographic domains (such as the southern part of the «Canavese Zone»), or to tectonites derived from lithologies of the two adjoining domains (such as the «Scisti di Fobello e Rimella», see below). Because of their complex internal setting it has been diffi cult to assign each single slice to a given palaeogeographic domain. Two main tectonic slice zones have been distinguished in the Piemonte map: The Canavese Zone and the Sestri-Voltaggio Zone. The Canavese Zone is exposed along the inner margin of the Western Alpine belt as a tectonic strip zone between the Austroalpine and Southalpine domains. The Sestri- Voltaggio Zone occurs along the contact between the Voltri Unit and the non-metamorphic Ligurian units of the Northern Apennines.

Canavese Zone The Canavese Zone is a composite tectonic domain cropping out from Levone to the SW (Canavese region) to the Italy-Switzerland border, east of Domodossola. This tectonic domain has been studied and mapped in detail (Baggio, 1963, 1965 a,b; Zingg et al , 1976; Biino & Compagnoni, 1989; Schmid et al ., 1989; Borghi et al . 1996, Ferrando, 1999; Ferrando et al ., 2004). It is bounded, on both sides, by two branches of the «Canavese Line» system (Schmid et al ., 1987; Bigi et al ., 1990). The Canavese Zone consists of pre-Permian basement slices ( ZC1 ) locally intruded by Permian granitoid and minor hornblende gabbro, Permian rhyolite (quartz-porphyry of the old literature) ( ZC2 ), as well as slivers of quartzite and Mesozoic carbonate sedimentary successions ( ZC3 ), including Triassic dolostone and possibly Jurassic dark schist and siliceous limestone («Biò Schists» sensu Biino & Compagnoni, 1989), i.e. , lithologies very similar to those of the palaeo- Adriatic margin (Ferrando et al ., 2004). Along the inner part of the Canavese Line, up to several hundred-metre-thick phyllonite and fault rocks ( ZC4 ), mainly derived from Ivrea-Verbano lithotypes and Permian volcanics of the 86 Fabrizio Piana et alii

Canavese Zone, are often found. In its northeastern portion (to the north of Valsessera), the Canavese Zone consists mainly of mylonitic schist and phyllonite, known as «Scisti di Fobello e Rimella» (Baggio, 1966; Sacchi, 1977) derived from the pervasive shearing of lithotypes of both the adjoining units (Sesia-Lanzo Zone and Ivrea-Verbano Zone) with remnants of Mesozoic sediments (Schmid et al ., 1987). The Canavese Zone includes also, in its southwesternmost part, the Pesmonte lizardite serpentinite (ZCO), a hectometre-scale tectonic mantle- slice, locally in contact with radiolarian chert (Baggio, 1966; Sturani 1973, 1975; Barnes et al., 2014). The Canavese Zone underwent an Alpine very low-grade metamorphic re-equilibration under the prehnite-pumpellyite-actinolite facies (Liou et al ., 1985, Biino & Compagnoni, 1989). The reader is reminded that several Geological Units (mostly consisting of tectonic slices) belonging to the transition zone between the Piemonte-Liguria Ocean and the palaeo-Adriatic continental margin (see Beltrando et al ., 2014, 2015a, 2015b) have been also included in the Canavese zone.

Sestri-Voltaggio Zone The Sestri-Voltaggio Zone is a north-south striking zone where several tectonic units were involved in response to ductile and brittle deformations which occurred at diff erent structural levels ( i.e., P-T conditions) and during diff erent tectonic stages (Crispini et al . 2009). The Sestri-Voltaggio Zone is juxtaposed, on its western side, to the Voltri and Palmaro-Caff arella tectonometamorphic units (here ascribed to the Liguria-Piemonte Oceanic Domain) along a regional, N-S directed shear zone, known as the «Sestri-Voltaggio Line». This Line has been interpreted as a transform fault (Elter & Pertusati, 1973), a thrust (Cortesogno & Haccard, 1984), or as an extensional fault (Hoogerduijn Strating, 1994) that most likely emphasise three successive stages of its evolution. On its eastern side, the Sestri-Voltaggio Zone shows a poorly exposed tectonic contact (Cortesogno & Haccard, 1979) with the Argilliti di Mignanego, belonging to Upper Cretaceous Ligurian units (Helminthoides Flysch). The Sestri-Voltaggio Zone consists of three tectonometamorphic units: the Gazzo-Isoverde Unit , originated from the distal part of the palaeo-European continental margin, the Cravasco-Voltaggio and Figogna units , originated from the Liguria-Piemonte Oceanic Domain (Cortesogno & Haccard, 1984). These units were involved at diff erent depths in the Alpine accretionary prism and tectonic belt: the Cravasco-Voltaggio and Gazzo-Isoverde units bear evidence of blueschist-facies metamorphism, while the Figogna unit was only aff ected by a pumpellyite-actinolite facies metamorphism (Crispini et al ., 2009). Geological Map of Piemonte Region at 1:250,000 scale 87

The Gazzo-Isoverde Unit consists mainly of Norian dolostone (GZI) overlain by slivers of gypsum, late Norian-Pliensbachian limestone (GLL), and schist of supposed late Early-Middle Jurassic age (Lualdi, 1991). The Cravasco-Voltaggio Unit is composed of serpentinite (SPV), metagabbro (CVOg ) and metabasalt ( CVOo ), and the relevant sedimentary cover consisting of siliceous metasediment, limestone and marble (VOL ), and metapelite (LRV ). The meta-ophiolite of the Cravasco-Voltaggio Unit locally preserves evidence of high-temperature oceanic metamorphism. The Figogna Unit, which mainly crops out in Liguria, a few kilometres to the south of the Piemonte boundary, consists of very low grade pillowed and brecciated metabasalt, minor serpentinite and ophicarbonate ( FIM ) and the relevant sedimentary cover consisting of calcareous schist and slate ( AGI , AGF ), largely exposed in Piemonte in the Fraconalto-Passo della Bocchetta area.

Alpine synorogenic magmatic bodies and dykes, and associated volcano- sedimentary covers During the Oligocene, in the frame of the on-going Alpine collisional stage, the supposed breakoﬀ of the subducted European lithospheric slab and the upwelling of hot asthenosphere induced the production and emplacement of calc-alkaline and ultra-K magmas (Dal Piaz et al . 1979; Venturelli et al ., 1984; Dal Piaz & Gosso, 1994; Davies & von Blanckenburg, 1995; von Blanckenburg & Davies, 1995; Rosenberg, 2004). These magmas rose along the Periadriatic line and the Sesia Lanzo Zone (see above) giving origin to a number of plutons, dykes and volcanics (described as «Periadriatic calc- alkaline post-collisional magmatic belt» by Bigi et al ., 1990). In Piemonte, this Periadriatic magmatic system consists of the following intrusive bodies:

Biella Pluton (Valle del Cervo Pluton) This pluton is exposed some kilometres to the northwest of Biella in the Cervo Valley (Fiorentini Potenza, 1959; Bigioggero et al ., 1994). It was emplaced into the «Eclogitic Micaschists» Complex of the Sesia-Lanzo Zone at a depth of 5-7 km (Berger et al ., 2012; Zanoni, 2016). The Biella Pluton shows a concentric zoning with the outer part made up of monzonite grading inwards to a syenite, which is surrounding a granitoid core.

– Monzonite ( PCEm) is the most widespread igneous lithotype, which consists of coarse-grained monzonite to quartz-monzonite containing up to dm-sized maﬁ c enclaves and xenoliths. Dm-thick leucocratic dykes are also present. At the contact with country rocks, monzonite becomes ﬁ ner- grained and richer in biotite. 88 Fabrizio Piana et alii

– Syenite ( PCEs, Fig. 13d) is a purple to brown syenite (« Sienite della Balma») mainly consisting of K-feldspar, amphibole with clinopyroxene remnant, plagioclase and biotite, and a large variety of accessory minerals including uraninite. – Granitoid ( PCEg): it is a medium- to coarse-grained, porphyritic monzo- granite to quartz-poor granodiorite, showing, towards the contact to the Syenite zone, a decrease in the quartz content and K-feldspar grain size (Pagliani Peyronel, 1959; Rossetti et al., 2007).

Both Monzonite and Syenite show a well-developed magmatic foliation marked by the preferred orientation of K-feldspar laths. Intrusive relationships suggest that the Monzonite crystallized fi rst, followed by the Syenite and fi - nally by the granite-granodiorite suite (Fiorentini Potenza, 1959; Bigioggero et al., 1994). Several small satellite igneous bodies, related to the Biella pluton, have been recognized within the country Sesia-Lanzo Zone. These include hornblende-biotite monzogabbro, gabbronorite to quartz-diorite, cordierite-bearing quartz-monzodiorite and syenite (Rossetti et al ., 2007 with references therein). Tourmaline-bearing hydrothermal breccias and veins (quartz-plagioclase-, quartz-tourmaline- and ankerite-quartz-sulphide- bearing veins) occur within both the intrusive rocks and the Sesia-Lanzo Zone country rocks (Rossetti et al ., 2007). The age of the Biella intrusion was determined, for the central part, at 30.3 ± 0.5 Ma (Bigioggero et al., 1994; Romer et al., 1996; Berger et al., 2012). After the emplacement of the Biella pluton, a signifi cant rotation of the inner part of the country Sesia-Lanzo Zone occurred along an axis roughly parallel to the Canavese line (Lanza, 1977, 1984). In the Piemonte Geological Map also the contact metamorphic aureole, developed all around the Biella pluton, is distinguished ( PBTa ). This is evident within the Sesia-Lanzo Eclogitic Micaschists country rocks (Fornasero, 1978; Zanoni et al ., 2007) where the lowest-grade mineral isograde is defi ned by biotite. The contact is locally marked by a 10 m-thick intrusive breccia composed of cm- to m-sized hornfels xenoliths of the country micaschist and gneiss embed- ded in a fi ne-grained quartz monzonite matrix (Rossetti et al ., 2007).

Miagliano tonalite Pluton The Miagliano tonalite l.s. (PMA) (Carraro & Ferrara, 1968), located on the southeastern side of the Canavese Line in the lower Cervo Valley, is intrusive into the Ivrea-Verbano mafi c granulite. The Miagliano Pluton has an Geological Map of Piemonte Region at 1:250,000 scale 89 approximate concentric structure and consists of a fi ne-grained monzodiorite to tonalite core rimmed by diorite. It is considered as an intermediate stage of a calc-alkaline magma diff e- rentiated at pressures of about 0.46 GPa, corresponding to a depth of about 12–15 km (Berger et al ., 2012). High precision zircon geochronology yielded an age of 33.00 ± 0.04 Ma for the central tonalitic part of the Miagliano Pluton (Berger et al., 2012).

Brosso-Traversella Pluton The Brosso-Traversella Pluton did emplace into the «Eclogitic Micaschists» Complex of the Sesia-Lanzo Zone at about 30 Ma ago (biotite K/Ar age; Krummenacher & Evernden, 1960). It is composed mostly of diorite to quartz- diorite ( PBT ) with minor monzonite, and consists of biotite, augite, hornblende, plagioclase, quartz and K-feldspar. Maﬁ c cumulates, consisting of biotite, augite, ilmenite and magnetite, and abundant xenoliths of the country rocks also occur. Various granitic to aplitic dykes cut across the main dioritic body (van Marcke de Lummen & Vander Auwera, 1990; Alagna et al ., 2010; Zanoni, 2010). The Brosso-Traversella Pluton is connected to important skarn and ore deposits mined for iron from the Roman period up to 1969: the pyrite deposit of Brosso and the magnetite deposits of Traversella. The skarns, described by Vander Auvera & Andre (1990), are located in the contact aureole ( PBTa) (Wirth, 1986).

«Biella volcano-sedimentary suite» («Biella Volcanic Suite») This suite consists of a volcanic to volcaniclastic sequence ( ANS) that occurs as a narrow, steeply dipping belt truncated by the Canavese Line on its SE side and includes also andesite dykes (Fig. 13c). It is considered the post- metamorphic Tertiary cover of the «Eclogitic Micaschists» Complex of the Sesia-Lanzo Zone (Bigi et al ., 1990; Callegari et al ., 2004) and consists of lava fl ows and prevailing pyroclastic and epiclastic deposits ranging in composition from basaltic andesite and andesite of high-K calc-alkaline affi nity to trachy-andesite and trachy-dacite of shoshonitic affi nity (Medeot et al ., 1997; Callegari et al., 2004). The «Biella Volcanic Suite», attributed to the Oligocene by Scheuring et al . (1974), Hunziker (1974) and Zingg et al . (1976), Dal Piaz et al . (1979), has been recently dated with more detail at 32.4-32.8 Ma (Kapferer et al., 2012). The similarity of geochemical features between lavas and intrusive rocks, as well as the same emplacement age, suggest that all the igneous rocks of the Biella district are comagmatic and belonging to a single volcano-plutonic complex (Callegari et al., 2004). 90 Fabrizio Piana et alii

The Biella Volcanic Suite and the adjacent rocks of the Sesia–Lanzo zone were exposed to the surface in Messinian times, after a long residence at low temperatures (c.120°C) corresponding to the apatite partial annealing zone (Kapferer et al., 2012).

Other features in the map legend

Fault rocks Carnieule (Cargneule; Tectonic breccia; BCC) Prevailing carbonate polygenic breccias formed mainly by dissolution of dolostone and marble, by hydrous ﬂ uid percolation. They are scattered along the main tectonic contacts and are commonly associated to gypsum bodies. These rocks have been often labelled in the Alpine geologic literature as «Carnieules» (e.g., Malaroda et al ., 1970; Warrack, 1974; Vearncombe, 1982). Anyway, this term was frequently used in the local regional literature to describe other rock types of controversial or mixed origin, such as hydrothermal breccia, dissolution breccia and travertine, and cemented subaerial slope breccia (e.g., Debenedetti & Turi, 1975; Debelmas et al ., 1980; Alberto et al ., 2007). In the Piemonte Geological Map, the «tectonic breccia» refers solely to the «Carnieules» preserved along tectonic contacts and originated, by tectonic processes, at the expense of carbonate and sulphate (gypsum/anhydrite) bodies.

Undiﬀ erentiated sedimentary and metasedimentary units preserved along the main tectonic contacts Gypsum (GES) Hectometre-sized gypsum bodies occur along the main tectonic contacts between oceanic units of the Liguria-Piemonte domain and metasedimentary units, which overlie the polycyclic basement of the palaeo-European continental margin (e.g., in the upper Susa Valley).

Marble and dolostone slivers Scattered bodies of marble and dolostone, traditionally referred to the Triassic, are tectonically juxtaposed to continental units and/or occurring along major tectonic zones at the contact between continental and oceanic units (UMTz).

«Incertae sedis» marble, quartzite and calc-schist (PLC) Slivers of marble, quartzite and calc-schist, preserved along tectonic Geological Map of Piemonte Region at 1:250,000 scale 91 contact with the polycyclic basement units of northern Piemonte are of uncer- tain palaeogeographic attribution.

Man-made deposits (w) They include the waste material from quarry activities (e.g., Bessa gold mine, Balangero asbestos mine) or garbage dump.

Symbols Main tectonic contacts and faults Two distinct orders of symbols, represented by red lines with diﬀ erent thickness, have been used for the tectonic contacts. These contacts mark the boundaries either between main tectonometamorphic and tectonostratigraphic units, or between minor tectonic features internal to a single unit. Stratigraphic unconformities The most signiﬁ cant unconformities (see above, section «Lithostratigraphic criteria-Metamorphic and Sedimentary rocks»), correlatable at regional scale, have been reported in the Map with a continuous blue line. 92 Fabrizio Piana et alii

7. Methods used for Map Representation and Data Base management The geological map is drawn at 1:250,000 scale and covers an area of approximately 25,400 km 2, corresponding to the whole Piemonte territory. The geological data represented in the map derive from a revision of both offi cial and unoffi cial geological maps, which have been locally integrated with un- published original data. The revision and harmonization of the existing data have been based on the criteria described in section «Criteria for Geological Classifi cation and Map Representation». A geological database was created using ESRI® ArcGis suite and QuantumGIS version 2.8.

8. The Topographic base of the Piemonte Geological Map Geological data were represented on a vector topographic base (Coordinate System WGS 1984 UTM, Zone 32N) prepared by Arpa Piemonte, modifying the regional topographic map (Base Topografi ca Multiscala Transfrontaliera), realized in 2015. This map, available from the Arpa Piemonte Geoportal (http://webgis.arpa. piemonte.it/ags101free/rest/services/topografi a_dati_di_base/Topografi ca_ Base_Multiscala_WM/MapServer), is composed of several layers (Toponymy ; Hydrography; Built-up areas ; Administrative boundaries) here modifi ed for a better legibility of geology layers, and a Hill-shade layer (Digital Terrain Model (30 m) ASTER 2, NASA; Digital Terrain Model (5 m), ICE 2010, Regione Piemonte). References

- Abbate, E. & Sagri, M. (1970). Development of the Northern Apennines geosyncline. The eugeosynclinal sequences. Sedim. Geol., 4, 251-240. - Aimone, S. & Ferrero Mortara, E. (1983). Malacofaune plioceniche di Cossato e Candelo (Biellese, Italia NW). Boll. Mus. Reg. Sci. Nat. (Torino), 1 (2), 276-328. - Alagna, K.E., Peccerillo, A., Martin, S. & Donati, C. (2010). Tertiary to Present evolution of orogenic magmatism in Italy. J. Virtual Explorer , 36, 1-63. - Alberto, W., Carraro, F., Giardino, M. & Tiranti, D. (2007). Genesis and evolution of ‘pseudocarniole’: Preliminary observations from the Susa Valley (Western Alps). In: B.C. Schreiber, S. Lugli & M. Babel (Eds.). Evaporites through Space and Time. Geol. Soc. London, Spec. Publ., 285, 155-168. - Amstutz, G.C. (1971). Carte tectonique de l’Ossola aux Grisons. Arch. Sci. Genève, 24, 5-9. - Arata J.F. (1982). Studio geologico, petrografico e geochimico del Massiccio ofiolitico Monginevro-Chenaillet (Alpi Cozie), con particolare riguardo alla evoluzione metamorfica alpina. Università di Torino , MSc Thesis, 185 p., with a 1:10.000 geologic map. - Arata J.F., Compagnoni R. & Sandrone R. (1981). Caratteri e distribuzione del metamorfismo nei lembi ofiolitici dell’area del Monginevro-Chenaillet (Alpi Cozie). SIMP Meeting, Abano Terme (Padova), 3-4 June, 1982. Rend. Soc. It. Mineral. Petrol ., 38, (1982-1983), Abs., p. 899. - Argand, E. (1909). L’exploration gé ologique des Alpes pennines centrales. Bull. Soc. Vaudoise Sci. nat., 45, 217-276. - Argand, E. (1911). Les nappes de recouvrement des Alpes Pennines et leurs prolongements structuraux. Beiträge geol. Karte Schweiz, 31, 1-26. - Argand, E. (1916). Sur l’arc des Alpes Occidentales. Eclogae geol. Helv., 14, 145-204. - Artini, E. & Melzi, G. (1900). Ricerche petrografiche e geologiche sulla Valsesia. Mem. R. Istituto Lombardo Sci. Lett., 18, 219-390. - Azzaroli A. & Cita, M.B. (1969). Studi illustrativi della carta geologica d’Ita- lia: formazioni geologiche, fascicolo III. Serv. Geol. It., Roma, 1-177. - Babist, J., Handy, M.R., Konrad-Schmolke, M. & Hammerschmidt, K. (2006). Precollisional, multistage exhumation of subducted continental crust: The Sesia Zone, western Alps. Tectonics , 25. Doi: 10.1029/2005TC001927. 94 References

- Baechlin, R. (1937). Geologie und Petrographie des Monte Tamaro-Gebietes (südliches Tessin). Schweiz. mineral. petrogr. Mitt., 17, 1-79. - Baggio, P. (1963a). Sulla presenza di una serie titonico-cretacea nel Canavese s.s. (Prealpi Piemontesi). Atti Ist. Veneto Sci. Lett. Arti, 121, 215-234. - Baggio, P. (1963b). Osservazioni geologiche sulla zona del Canavese s.s., nel tratto Cuorgné-Issiglio (Prealpi Piemontesi). Atti Accad. Sci. Torino, 97, 1-22. - Baggio, P. (1965a). Geologia della zona del Canavese nel settore occidentale Levone-Cuorgnè (Prealpi Piemontesi). Mem. Accad. Patavina Sci. Lett. Arti, 77, 41-71. - Baggio, P. (1965b). Caratteri stratigrafici e strutturali del Canavese s.s. nella zona di Montalto Dora. Mem. Ist. Geol. Miner. Univ. Padova, 25, 1-25. - Baggio, P. (1966). Il problema geologico degli «Scisti di Fobello e Rimella» nell’alta Val Mastallone (Varallo Sesia, Provincia di Vercelli). Boll. Soc. Geol. It ., 85 (2), 253-273. - Bagnoud, A., Wernli, R. & Sartori, M. (1998). Découverte de foraminifères paléogènes planctoniques dans la zone de Sion-Courmayeur à Sion (Valais, Suisse). Eclogae geol. Helv. 91 (3), 421-429. - Balconi, M. (1963). Il contatto tra graniti e porfidi tra la Valsessera e il Biellese (comunicaz. prelim.). Rend. Soc. It. Mineral. Petrol ., 19, 17-23. - Balconi, M. & Zezza U. (1965). I rapporti tra i graniti e i porfidi nel Biellese. Per. Miner., 34, 257-314. - Baldacci L. & Franchi, S. (1900). Studio geologico della Galleria del Col di Tenda (linea Cuneo-Ventimiglia). Boll. R. Com. Geol. Italia, 31, 33-114. - Balestro G., Cadoppi P., Fioraso G., Polino R. & Tallone S. (2009). Foglio 155 «Torino Ovest», Geological Map of Italy, 1:50,000 scale. ISPRA, It. Geol. Survey, Roma, Italy. - Balestro, G., Fioraso, G. & Lombardo, B. (2013). Geological map of the Monviso massif (Western Alps). J. Maps, 9 (4), 623-635. - Ballèvre, M., (1988). Collision continentale et chemins P-T: L’unité pennique du Grand Paradis (Alpes occidentales). Mém. Doc. Centre Armoricain d’Etu- des Structurales des Socles (Mém. Géosci. Rennes), 19, 1-352. - Barale, L., Bertok, C., d’Atri, A., Domini, G., Martire, L. & Piana, F. (2013). Hydrothermal dolomitization of the carbonate Jurassic succession in the Provençal and Subbriançonnais Domains (Maritime Alps, North-Western Italy). C.R. Geosci., 345, 47-53. - Barale, L., Bertok, C., d’Atri, A., Martire, L., Piana, F. & Domini, G. (2016a). Geology of the Entracque-Colle di Tenda area (Maritime Alps, NW Italy). J. Maps, 12 (2), 359-370. References 95

- Barale, L., Bertok, C., Salih Talabani, N., d’Atri, A., Martire, L., Piana, F. & Préat, A. (2016b). Very hot, very shallow hydrothermal dolomitization: An example from the Maritime Alps (NW Italy-SE France). Sedimentology, 63 (7), 2037-2065. - Barale, L., Bertok, C., d’Atri, A., Martire, L. & Piana, F. (2017). Stratigraphy, sedimentology and syndepositional tectonics of the Jurassic-Cretaceous succession at the transition between Provençal and Dauphinois domains (Maritime Alps, NW Italy). Riv. It. Paleont. Strat., 123 (3), 355-378. - Barbieri, M.A. (1996). Petrologia dei corpi peridotitici minori in Val Grande (zona Ivrea-Verbano Settentrionale). Atti Tic. Sci. Terra, 4, 121-128. - Barféty, J.C., Lemoine, M., de Graciansky, P.C. et al. (1996). Carte géol. France (1/50 000), feuille Briançon (823). Bureau de Recherches Géologiques et Minières , Orléans. - Barnes, J.D., Beltrando, M., Lee, C.T.A., Cisneros, M., Loewy, S. & Chin, E. (2014). Geochemistry of Alpine serpentinites from rifting to subduction: A view across palaeogeographic domains and metamorphic grade. Chem. Geol., 389, 29-47. - Basilici, G., Martinetto, E., Pavia, G. & Violanti, D. (1997). Paleoenvironmental evolution in the Pliocene marine-coastal succession of Val Chiusella (Ivrea, NW Italy). Boll. Soc. Paleont. It., 36 (1-2), 23-52. - Battiston, P.P., Benciolini, L., Dal Piaz, G.V., De Vecchi, G., Marchi, G., Martin, S., Polino, R. & Tartarotti, P. (1987). Geologia di una traversa dal Gran Paradiso alla Zona Sesia-Lanzo in alta val Soana, Piemonte. Mem. Soc. Geol. It., 29 (1984), 209-232. - Bearth, P. (1939). Über den Zusammenhang von Monte Rosa- und Bernhard- Decke. Eclogae geol. Helv., 32, 101-111. - Bearth, P. (1952). Geologie und Petrographie des Monte Rosa. Beiträge geol. Karte Schweiz (Neue Folge), 96, 1-94. - Bearth, P. (1953). Blatt Zermatt. Geologischer Atlas der Schweiz. Nr. 29. Schweiz. Geol. Kommission, Basel. - Bearth, P. (1956). Geologische Beobachtungen im Grenzgebiet der lepontini- schen und penninischen Alpen. Eclogae geol. Helv., 49 (2), 279-290. - Bearth, P. (1958). Über einen Wechsel der Mineralfazies in der Wurzelzone des Penninikums. Schweiz. mineral. petrogr. Mitt., 38, 363-373. - Beaumont C. (1981). Foreland basins. Geoph. J. Royal Astron. Soc ., 65, 291-329. - Beccaluva, L., Dal Piaz, G.V., Macciotta, G. & Zeda, O. (1979). The Austroalpine harzburgite body of the Artogna valley (Italian Western Alps). Mem. Ist. Geol. Mineral. Univ. Padova, 33, 173-181. 96 References

- Bellinzona, G. & Boni, A. (1971). Stratigrafia e tettonica della zona tra il T. Scrivia e il T. Sisola. Atti Ist. Geol. Univ. Pavia, 21, 121-137. - Bellinzona, G., Boni, A., Braga, G. & Marchetti, G. (1971). Note illustrative della Carta Geologica d’Italia in scala 1:100.000, Foglio 71 - Voghera, Serv. Geol. d’Italia, 121, Roma. - Beltrando, M., Compagnoni, R. & Lombardo, B. (2010). (Ultra-) High- pressure metamorphism and orogenesis: An alpine perspective. Gondwana Research , 18, 1-20. - Beltrando, M., Manatschal, G., Mohn, G., Dal Piaz, G.V., Vitale Brovarone, A. & Masini, E. (2014). Recognizing remnants of magma-poor rifted margins in high-pressure orogenic belts: The Alpine case study. Earth Sci. Reviews, 131, 88-115. - Beltrando, M., Compagnoni, R., Ferrando, S., Mohn, G., Frasca, G., Odasso, N., Vukmanovič , Z. & Masini, E. (2015a), Crustal thinning and mantle exhumation in the Levone area (Southern Canavese Zone, Western Alps). In: G. Manatschal et al. (Eds.). A Field Guide across the Margins of Alpine Tethys, J. Virtual Explorer , 48. Doi: 10.3809/jvirtex.2013.00326. - Beltrando, M., Stöckli, D.F., Decarlis, A. & Manatschal, G. (2015b). A crustal- scale view at rift localization along the fossil Adriatic margin of the Alpine Tethys preserved in NW Italy. Tectonics , 34 (9), 1927-1951. - Berger, A., Mercolli, I. & Engi, M. (2005). The Central Lepontine Alps: Expla- natory notes of the tectonic-geological map, Sheet Sopra Ceneri (1:100,000). Schweiz. mineral. petrogr. Mitt, 85, 109-146. - Berger, A. & Mercolli, I. (2006). Tectonic and Petrographic Map of the central Lepontine Alps. 1:100,000, v. 127. Wabern (Suisse). Office fedé rale de topo- graphie, Wabern. - Berger, A. & Bousquet, R. (2008). Subduction related metamorphism in the Alps: Review of isotopic ages based on petrology and their geodynamic consequences. In: S. Siegesmund, B. Fügenschuh & N. Froitzheim (2008). Tectonic Aspects of the Alpine-Dinaride-Carpathian System. Geological Society, London, Spec. Publ., 298, 117-144. - Berger, A., Thomsen, T. B., Ovtcharova, M., Kapferer, N. & Mercolli, I. (2012). Dating emplacement and evolution of the orogenic magmatism in the internal Western Alps: 1. The Miagliano Pluton. Swiss J. Geosci ., 105 (1), 16-61. - Bergomi, M.A., Tunesi, A., Shi, Y.-R. et al. (2007). SHRIMP II U/Pb geochronological constraints of pre-Alpine magmatism in the Lower Penninic Units of the Ossola Valley (Western Alps, Italy). Geophys. Research Abs., 9, 07780, EGU. - Bernoulli, D., Caron, C., Homewood, P. et al. (1979). Evolution of continental margins in the Alps. Schweiz. mineral. petrogr. Mitt., 59, 165-170. References 97

- Bernoulli, D., Heitzmann, P. & Zingg, A. (1990). Central and Southern Alps in Southern Switzerland: tectonic evolution and first results of reflection sei- smics. In: F. Roure, P. Heitzmann & R. Polino (Eds.). Deep Structure of the Alps. Mém. Soc. Géol. Fr ., 156, Mém. Soc. Géol. Suisse, 1, Vol. Sp., Mem. Soc. Geol. It.., 1, 289-302. - Bernoulli, D. & Jenkins, H. (2009). Ancient oceans and continental margins of the Alpine-Mediterranean Tethys: Deciphering clues from Mesozoic pelagic sediments and ophiolites. Sedimentology, 56, 147-190. - Berra, F., Galli, M.T., Reghellin, F. et al. (2009). Stratigraphic evolution of the Triassic-Jurassic succession in the Western Southern Alps (Italy): The record of the two-stage rifting on the distal passive margin of Adria. Basin Research , 21, 335-353. - Bersezio, R., Barbieri, P. & Mozzi, R. (2002). Redeposited limestones in the Upper Cretaceous succession of the Helvetic Argentera Massif at the Italy- France border. Eclogae geol. Helv., 95,15-30. - Bertolani, M. (1954). Contributo allo studio petrografico della cosiddetta «Formazione diorito-kinzigitica». Ricerche in Val Sabbiola (Val Sesia). Rend. Soc. Min. It., 10, 2-119. - Bertolani, M. (1958). Contributo allo studio petrografico della cosiddetta «Formazione diorito-kinzigitica»: le azioni metamorfiche nelle rocce di Bagnola (Val Sesia). Rend. Soc. Min. It., 14, 3-64. - Bertolani, M. (1960). Contributo allo studio petrografico della cosiddetta «Formazione diorito-kinzigitica». Variabilità petrografica ed azioni metamorfiche nella zona di Civiasco (Val Sesia). Per. Miner., 29, 193-268. - Bertoldi, R. & Martinetto, E. (1995). Ricerche paleobotaniche (palinologi- che e paleocarpologiche) sulla successione «villafranchiana» del Rio di Cà Viettone. Il Quaternario, 8 (2), 403-422. - Bertok, C., Martire, L., Perotti, E., d’Atri, A. & Piana, F. (2012). Kilometre- scale palaeo-escarpments as evidence for Cretaceous synsedimentary tectonics in the External Brianç onnais Domain (Ligurian Alps, Italy). Sediment. Geol., 251, 58-75. - Bertotti, G., Mosca, P., Juez, J., Polino, R. & Dunai, T. (2006). Oligocene to Present kilometres scale subsidence and exhumation of the Ligurian Alps and the Tertiary Piedmont Basin (NW Italy) revealed by apatite (U-Th)/He thermochronology correlation with regional tectonics. Terra Nova , 18 (1), 18-25. - Bertotti, G. & Mosca, P. (2009). Late-orogenic vertical movements within the arc of the SW Alps and Ligurian Alps. Tectonophysics , 475 (1), 117-127. - Bertrand, J., Courtin, B. & Vuagnat, M. (1982). Elaboration d’un secteur de lithosphère océanique liguro-piémontais d’après les données de l’ophiolite de 98 References

Montgenèvre (Hautes-Alpes, France et Province de Turin, Italie). Ofioliti, 2 (3), 155-196. - Bertrand, J.M., Pidgeon, T., Leterrier, J., Guillot, F., Gasquet, D. & Gattiglio, M. (2000). SHRIMP and IDTIMS U-Pb zircon ages of the pre-Alpine basement in the Internal Western Alps (Savoy and Piemont). Schweiz. mineral. petrogr. Mitt., 80, 225-248. - Biancotti, A. (1979). Il Quaternario dell’area compresa fra Stura di Demonte e Tanaro (Piemonte sud-occidentale). Rend. Acc. Naz. Lincei, 66, 1-9. - Biella, G.C., Gelati, R., Maistrello, M., Mancuso, M., Massiotta, P. & Scarascia, S. (1987). The structure of the upper crust in the Alps-Apennines boundary region deduced from refraction seismic data. Tectonophysics , 142, 71-85. - Biella, G.C., Gelati, R., Rossi, P.M. & Tabacco, I. (1988). Sezioni geologiche nella zona limite Alpi occidentali-Appennino settentrionale ottenute da dati geofisici. Rend. Soc. Geol. It., 11, 287-292. - Biella, G., Polino, R., de Franco, R., Rossi, P.M., Clari, P.A., Corsi, A. & Gelati, R. (1997). The crustal structure of the western Po plain: Reconstruction from the integrated geological and seismic data. Terra Nova , 9, 28-31. - Bigi, G., Castellarin, A., Coli, M., Dal Piaz, G.V., Sartori, R., Scandone, P. & Vai, G.B. (1990). Structural Model of Italy, sheet 1, C.N.R., Progetto Finalizzato Geodinamica, Litografia SELCA, Firenze. - Bigioggero, B., Boriani, A., Colombo, A., Gregnanin, A., Ben, G., Coccolo, V., Forlati, F., Lavazza, F., Lazzari, A., Massazza, G., Morandi, C., Olivero, A., Puma, F., Quaglia, R., Santini, G. & Stoppa, T. (1981). Carta geolitologica delle valli Vigezzo, Fenecchio e Basso Isorno. Scala 1:25.000. Regione Piemonte. Assessorato alla Pianificazione Territoriale. Servizio Geologico . Tipografia SELCA, Firenze. - Bigioggero, B., Colombo, A., Del Moro, A., Gregnanin, A., Macera, P. & Tunesi, A. (1994). The Oligocene Valle del Cervo Pluton: An example of shoshonitic magmatism in the Western Italian Alps. Mem. Sci. Geol ., 46, 409-421. - Biino, G. & Compagnoni, R. (1989). The Canavese Zone between the Serra d’Ivrea and the Dora Baltea River (Western Alps). Eclogae geol. Helv., 82, 413-427. - Bini, A., Borsato, A., Carraro, F. et al. (2004). Definitions of terminologies used in the mapping of Quaternary deposits in the Alpine area. It. J. Quat. Sci., 17, 75-82. - Bistacchi, A., Dal Piaz, G.V., Massironi, M., Zattin, M. & Balestrieri, M.B. (2001). The Aosta-Ranzola extensional fault system and Oligocene-Present evolution of the Austroalpine-Penninic wedge in the northwestern Alps. Int. J. Earth Sci., 90 (3), 654-667. References 99

- Boccaletti, M., Cerrina Feroni, A., Martinelli, P., Moratti, G., Plesi, G. & Sani, F. (1992). Compressive events in the Tyrrhenian side of the Northern Apennines. Annales Tectonicae, 6, 214-230. - Bogdanoff, S. (1986). Evolution de la partie occidentale du massif cristallin externe de l’Argentera placée dans l’arc alpin. Géologie de la France, 4, 433-453. - Boillot, G., Montadert, L., Lemoine, M. & Biju-Duval, B. (1984). Les marges continentales actuelles et fossiles autour de la France. Masson, Paris, 342 p. - Bonazzi, A., Cobianchi, M., Galbiati, B. (1987). Primi dati sulla cristallinità dell’illite delle unità tettoniche più esterne e strutturalmente elevate delle Alpi liguri. Atti Tic. Sci. Terra, 31, 63-77. - Bond, G.C., Kominz, M.A. & Sheridan, R.E. (1995). Continental Terraces and Rises. In: C.J. Busby & R.V. Ingersoll (Eds.). Tectonics of Sedimentary Basins . Blackwell Science, Cambridge, MA, 149-178. - Boni, A. & Casnedi, R. (1970). Note illustrative della Carta Geologica d’Italia alla scala 1:100.000, Fogli 69 e 70, Asti e Alessandria. Serv. Geol. d’Italia, Roma, 1-96. - Boni, A., Conti, S., Gelati R., Marchetti, G. & Passeri L.D. (1969). Note illustrative della Carta Geologica d’Italia in scala 1:100.000 Foglio 83-Rapallo/ Foglio 94-Chiavari. Serv. Geol. It., Roma, 1-89. - Bonsignore, G., Bortolami, G., Elter, G., Montrasio, A., Petrucci, F., Ragni, U., Sacchi, R., Sturani, C. & Zanella, E. (1969). Note illustrative dei Fogli 56-57, Torino-Vercelli della Carta Geologica d’Italia alla scala 1:100.000. Serv. Geol. It ., Roma, 1-96. - Borghi A. (1989). L’evoluzione metamorfico-strutturale del settore nord- orientale della Serie dei Laghi, (Alpi Meridionali). PhD Thesis, Univ. Torino, Italy, 187 p. (unpubl.). - Borghi, A., Compagnoni, R. & Naldi, M. (1996). The crystalline basement of the Canavese Zone (Internal Western Alps): New data from the area west of Ivrea (Northern Italy). Géol. Alpine, 72, 23-34. - Borghi, A., Gattiglio, M., Mondino, F. & Zaccone, G. (1999). Structural and metamorphic evidence of pre-alpine basement in the Ambin nappe (Cottian Alps, Italy). Mem. Sci. Geol., 51 (1), 205-220. - Boriani, A. & Giobbi Mancini, E., 1972. The feldspathized amphibolites of the «Strona-Ceneri Zone». Boll. Soc. Geol. It., 91, 655-681. - Boriani, A. & Sacchi, R. (1973). Geology of the junction between the Ivrea- Verbano and Strona-Ceneri Zones. Mem. Ist. Geol. Miner. Univ. Padova , 28, 1-36. - Boriani, A. & Sacchi, R. (1985). The Western Southalpine basement and its tectonic setting. In: D. Galson & S. Müller (Eds.). 2 nd Workshop European Geotraverse Project., 87-92. 100 References

- Boriani, A., Colombo, A., Origoni Giobbi, E. & Peyronel Pagliani, G. (1974). The «Appinite Suite» of Massiccio dei Laghi (Northern Italy) and its relationship to the regional metamorphism. Rend. Soc. It. Min. Petr., 30 (2), 893-917. - Boriani, A., Bigioggero, B. & Giobbi Mancini, E. (1977). Metamorphism, tectonic evolution and tentative stratigraphy of the «Serie dei Laghi». Geological map of the Verbania area (Northern Italy). Mem. Ist. Geol. Miner. Univ. Padova, 32, 1-26. - Boriani, A., Origoni Giobbi, E. & Del Moro, A. (1982). Composition, level of intrusion and age of the «Serie dei Laghi» orthogneisses (Northern Italy- Ticino, Switzerland). Rend. Soc. It. Min. Petr., 38 (1), 191-205. - Boriani A., Burlini, L. & Caironi, V. (1988). Carta geologica dei graniti dei laghi (Valsesia, Cusio Verbano - Province di Vercelli e Novara). Rend. Soc. It. Min. Petrol ., vol. 43. - Boriani, A., Burlini, L. & Sacchi, R. (1990a). The Cossato-Mergozzo- Brissago Line and the Pogallo Line (Southern Alps, Northern Italy) and their relationships with the late-Hercynian magmatic and metamorphic events. Tectonophysics , 182, 91-102. - Boriani, A., Origoni Giobbi, E., Borghi, A. & Caironi, V. (1990b). The evolution of the «Serie dei Laghi» (Strona-Ceneri and Scisti dei Laghi): The upper component of the Ivrea-Verbano crustal section; Southern Alps, North Italy and Ticino, Switzerland. Tectonophysics , 182, 103-118. - Boriani, A., Caironi, V., Giobbi Origoni, E. & Vannucci, R. (1992). The Permian intrusive rocks of Serie dei Laghi (Western Southern Alps). Acta Vulcanol ., 2, 73-86. - Boriani, A. & Burlini, L. (1995). Carta Geologica della Valle Cannobina. Comunità montana Valle Cannobina , Dip. Scienze Terra, Univ. Milano, Grafiche Diodoro, Milano. - Bottino, G., Cavalli, C., Eusebio, A. & Vigna, B. (1994). Stratigrafia ed evoluzione plio-quaternaria del settore sud-orientale della pianura cuneese. Atti Tic. Sci. Terra, serie speciale, 1, 153-166. - Bousquet, R., Oberhänsli, R., Goffé, B. et al. (2008). Metamorphism of metasediments in the scale of an orogen: A key to the Tertiary geodynamic evolution of the Alps. In: S. Siegesmund, B. Fügenschuh & N. Froitzheim (Eds.). Tectonic Aspects of the Alpine-Dinaride-Carpathian System. Geol. Soc. London, Spec. Publ., 298, 393-412. - Bozzo, E., Cattaneo, M., Giglia, G. & Pegoraro, G. (1985). Deep magnetic structures in the Piedmontese Tertiary Basin (Ligurian-Piedmontese area, Northern Italy). Boll. Geof. Teor. Appl ., 28 (109), 49-63. References 101

- Bozzo, E., Campi, S., Capponi, G. & Giglia, G. (1992). The suture between Alps and Apennines in the Ligurian sector based on geological and geomagnetic data. Tectonophysics , 206, 159-169. - Braga, G. (1965). Geologia delle valli del Nure e Perino (Appennino piacenti- no). Atti Ist. Geol. Univ. Pavia, 17, 3-49. - Brouwer, F.M., van de Zedde, D.M.A., Wortel, M.J.R. & Vissers. R.L.M. (2004). Late-orogenic heating during exhumation: Alpine PTt trajectories and thermomechanical models. Earth Planet. Sci. Letters, 220, 185-199. - Burckhardt, C.E. (1942). Geologie und Petrographie des Basodino-Gebietes (Nordwestliches Tessin). Schweiz. mineral. petrogr. Mitt., 22, 99-188. - Burlini, L. & Caironi, V. (1988). Geological and petrographical data on the Quarna pluton (Serie dei Laghi, Northern Italy). Rend. Soc. It. Min. Petr., 43 (2), 429-444. - Burri, M., Jemelin, L. & Jeanbourquin, P. (1994). Blatt 93, Brig (LK 1289), Erlaüterungen zur geologischen Karte der Schweiz 1:25,000. Landeshydrologie und Geologie, Bern. - Bussy, F. & Cadoppi, P. (1996). U-Pb zircon dating of granitoids from the Dora-Maira massif (Western Italian Alps). Schweiz. mineral. petrogr. Mitt ., 76 , 217-233. - Bussy, F., Venturini, G., Hunziker, J. & Martinotti, G. (1998). U-Pb ages of magmatic rocks of the western Austroalpine Dent-Blanche-Sesia Unit. Schweiz. mineral. petrogr. Mitt., 78, 163-168. - Cabella, R., Cortesogno, L. & Gaggero, L. (1991). Il basamento cristallino del torrente Visone. Rend. Soc. Geol. It., 14, 29-33. - Cadoppi, P. & Tallone, S. (1992). Structural and lithostratigraphic heterogeneity of the northern part of Dora-Maira Massif (Western Alps). Atti Tic. Sci. Terra , 35, 9-18. - Cadoppi, P., Castelletto, M., Sacchi, R., Baggio, P., Carraro, F., Giraud, V. & Bellardone, G. (1999). Note illustrative della Carta Geologica d’Italia alla scala 1:50.000. Foglio 154 Susa. Regione Piemonte, Direzione Regionale Servizi Tecnici di Prevenzione, Torino , 123 p. - Callegari, E., Compagnoni, R. & Dal Piaz, G.V. (1969). Relitti di strutture intrusive erciniche e scisti a sillimanite nel massiccio del Gran Paradiso. Boll. Soc. Geol. It., 88, 59-69. - Callegari, E., Sacchi, R., Bovo, S. & Torassa, G. (1980). Osservazioni strutturali sul versante italiano del Massiccio di Ambin (Alpi Graie). Boll. Soc. Geol. It ., 99, 395-404. - Callegari, E., Cigolini, C., Medeot, O. & D’Antonio, M. (2004). Petrogenesis of calc-alkaline and shoshonitic post-collisional Oligocene volcanics of the 102 References

Cover Series of the Sesia Zone, Western Italian Alps. Geodin. Acta , 17, 1-29. - Capponi, G. & Giammarino, S. (1982). L’affioramento oligocenico del Rio Siria (Bacino di Santa Giustina, Provincia di Savona), nel quadro dei movi- menti tardivi della falda di Montenotte. Atti Soc. Tosc. Sci. Nat ., 89, 101-113. - Capponi, G., Gosso, G., Scambelluri, M., Siletto, G. & Tallone, S. (1994). Carta geologico-strutturale del settore centro-meridionale del Gruppo di Voltri (Alpi liguri) e note illustrative. Boll. Soc. Geol. It., 133, 383-394. - Capponi, G. & Crispini, L. (2002). Structural and metamorphic signature of alpine tectonics in the Voltri Massif (Ligurian Alps, northwestern Italy). Eclogae geol. Helv., 95, 31-42. - Capponi, G. & Crispini, L. (2009). Note Illustrative del Foglio 213-230 «Genova», Carta Geologica d’Italia alla scala 1:50.000. Agenzia per l’Am- biente e il Territorio (APAT, Roma) - Regione Liguria, Selca, Firenze , 139 p. - Carminati, E. & Doglioni, C. (2012). Alps vs. Apennines: The paradigm of a tectonically asymmetric Earth. Earth-Sci. Reviews, 112 (1-2), 67-96. - Carrapa, B., Wijbrans, J. & Bertotti, G. (2003). Detecting provenance variations and cooling patterns within the Western Alpine orogen through 40 Ar/ 39 Ar geochronology on detrital sediments: The Tertiary Piedmont Basin, NW Italy. In: M., Bernet & C., Spiegel (Eds.). Detrital thermochronology, provenance analysis, exhumation and landscape evolution of mountain belts, GSA Special Publication, 378, 5. - Carraro, F. (1996). The Villafranchian in the Villafranca d’Asti type-area: A revision. Il Quaternario, 9, 5-120. - Carraro, F. & Ferrara, G. (1968). Alpine «tonalite» at Miagliano, Biella (Zona Dioritico-kinzigitica). Schweiz. mineral. petrogr. Mitt., 48, 75-80. - Carraro, F., Dal Piaz, G.V. & Sacchi, R. (1970). Serie di Valpelline e II Zona Diorito-Kinzigitica sono i relitti di un ricoprimento proveniente dalla Zona Ivrea-Verbano. Mem. Soc. Geol. It., 9, 197-224. - Carraro, F. & Sturani, C. (1972). Segnalazione di Toarciano fossilifero in facies austroalpina («Fleckenmergeln») nel lembo sedimentario di Sostegno (Biellese). Boll. Soc. Geol. It., 91, 407-417. - Carraro, F., Lanza, R., Perotto, A. & Zanella, E. (1991). L’evoluzione morfologica del Biellese occidentale durante il Pleistocene inferiore e medio, in relazione all’inizio della costruzione dell’Anﬁteatro Morenico d’Ivrea. Boll. Museo Reg. Sci. Nat. (Torino), 9, 99-117. - Carraro, F., Collo, G., Forno, M.G., Giardino, M., Maraga, F., Perotto, A. & Tropeano, D. (1995). L’evoluzione del reticolato idrografico del Piemonte centrale in relazione alla mobilità quaternaria. In: R. Polino & R. Sacchi (Eds.). Atti del convegno «Rapporti Alpi-Appennino e guide alle escursioni»: References 103

Peveragno (CN) 31 Maggio - 1 Giugno 1994. Acc. Naz. Scienze, Scritti e Doc., XIX, 445-461. - Cassano, E., Anelli, L., Fichera, R. & Cappelli, V. (1986). Pianura Padana: Interpretazione integrata di dati geofisici e geologici. 73° Congr. Soc. Geol. It ., Edizioni AGIP, Roma, 27 p. - Cassinis, G., Elter, G., Rau, A. & Tongiorgi, M. (1979). Verrucano: A tecto- facies of the Alpine-Mediterranean southern Europe. Mem. Soc. Geol. It ., 20, 135-149. - Cassinis, G., Massari, F., Neri, C. & Venturini, C. (1988). The continental Permian in the Southern Alps; a review. Zeitsch. Geol. Wissensch ., Berlin, 16, 1117-1126. - Cassinis, G., Perotti, C.R. & Ronchi, A. (2011). Permian continental basins in the Southern Alps (Italy) and peri-mediterranean correlations. Int. J. Earth Sci., 101 (1), 129-157. - Castellarin, A. (1994). Strutturazione eo- e meso-alpina dell’Appennino settentrionale attorno al «nodo ligure». Studi Geol. Camerti , vol. spec. CROP 1-1A, 99-108. - Castellarin, A., Cantelli, L., Fesce, A.M., Mercier, J., Picotti, V., Pini, G.A., Prosser, G. & Selli, L. (1992). Alpine compressional tectonics in the Southern Alps. Relations with the N-Apennines. Annales Tectonicae, 6, 62-94. - Castellarin, A., Piccioni, S., Prosser, G., Sanguinetti, E., Sartori, R. & Selli, L. (1993). Mesozoic continental rifting and Neogene inversion along the South Giudicarie Line (Northwestern Brenta Dolomites). Mem. Soc. Geol. It., 49, 125-144. - Castelli, D., Compagnoni, R., Lombardo, B., Angiboust, S., Balestro, G., Ferrando, S., Groppo, C. & Rolfo, F. (2014). Crust-mantle interactions during subduction of oceanic & continental crust. Day 1- The Monviso meta-ophiolite Complex: HP metamorphism of oceanic crust & interactions with ultramafics. 10 th Int. Eclogite Conference, Post-Conference Excursion, 9 Sept. 2013, GFT – Geological Field Trips, 6 (1.3), 1-73. - Castiglioni, G.B. (1958). Studio geologico e morfologico del territorio di Baceno e Premia (Val d’Ossola, Alpi Lepontine). Mem. Ist. Geol. Padova , 20, 1-82. - Cavagna, S., Clari, P., Dela Pierre, F., Martire, L. & Natalicchio, M. (2015). Sluggish and steady focussed flows through fine-grained sediments: The methane-derived cylindrical concretions of the Tertiary Piedmont Basin (NW Italy). Mar. Petrol. Geol., 66, 596-605. - Cavinato, G.P., Di Luzio, E., Moscatelli, M., Vallone, R., Averardi, M., Valente, A. & Papale, S. (2006). The new Col di Tenda tunnel between Italy and France: Integrated geological investigations and geophysical prospections for preliminary studies on the Italian side. Eng. Geol., 88, 90-109. 104 References

- Chang, K.H. (1975). Unconformity bounded stratigraphic units. Geol. Soc. Amer. Bull., 86, 1544-1552. - Chiesa, S., Cortesogno, L., Forcella, F., Galli, M., Messiga, B., Pasquaré, G., Pedemonte, G.M., Piccardo, G.B. & Rossi, P.M. (1975). Assetto strutturale ed interpretazione geodinamica del gruppo di Voltri. Boll. Soc. Geol. It ., 94, 555-581. - Chopin, C. (1984). Coesite and pure pyrope in high-grade blueschists of the Western Alps: A first record and some consequences. Contrib. Mineral. Petrol ., 86, 107-118. - Chopin, C. & Monié, P. (1984). A unique magnesiochloritoid-bearing high- pressure assemblage from the Monte Rosa, Western Alps: Petrologic and 40 Ar/39 Ar radiometric study. Contrib. Mineral. Petrol ., 87, 388-398. - Chopin, C., Henry, C. & Michard, A. (1991). Geology and petrology of the coesite-bearing terrain, Dora-Maira Massif, Western Alps. Eur. J. Miner ., 3, 263-291. - Cibin, U., Di Giulio, A. & Martelli, L. (2003). Oligocene-Early Miocene tectonic evolution of the northern Apennines (northwestern Italy) traced through provenance of piggy-back basin fill successions. In: T. McCann & A. Saintot (Eds.). Tracing Tectonic Deformation Using the Sedimentary Record. Geol. Soc. London, Spec. Publ., 208, 269-287. - Clari, P.A. & Ghibaudo, G. (1983). Carta Geologica dei depositi miocenici del margine Sud Orientale del bacino terziario ligure-piemontese (Valli Borbera, Scrivia e Lemme). CNR, Centro di studi sui problemi dell’orogeno delle Alpi occidentali. SELCA, Firenze. Boll. Soc. Geol. It., vol. 104, 1985. - Clari, P.A., Proto Decima, F., Ricci, B. & Sampò, M. (1987). Facies di piattafor- ma nell’Oligocene medio del Monferrato. Boll. Soc. Paleont. It ., 26, 109-118. - Clari, P.A., Gagliardi, C., Governa, M., Ricci, B. & Zuppi, G.M. (1988). I Calcari di Marmorito: una testimonianza di processi diagenetici in presenza di metano. Boll. Mus. Reg. Sci. Nat. (Torino), 6, 197-216. - Clari, P. A., Fornara, L., Ricci, B. & Zuppi, G.M. (1994). Methane-derived carbonates and chemiosymbiotic communities of Piedmont (Miocene), Northern Italy: An update. Geo. Mar. Lett., 14, 201-209. - Clari, P.A., Dela Pierre, F. & Martire, L. (1995a). Discontinuities in carbonate successions: Identification, interpretation and classification of some Italian examples. Sedim. Geol., 100, 97-121. - Clari, P.A., Dela Pierre, F., Novaretti, A. & Timpanelli, M. (1995b). Late Oligocene-Miocene sedimentary evolution of the critical Alps/Apennines junction: The Monferrato area, Northwestern Italy. Terra Nova , 7, 144-152. - Clari, P.A, Cavagna, S., Martire, L. & Hunziker, J. (2004). A Miocene mud References 105

volcano and its plumbing system: A chaotic complex revisited (Monferrato, NW Italy): J. Sed. Res., 74, 662-676. - Clari, P., Dela Pierre, F., Martire, L. & Cavagna, S. (2009). The Cenozoic

CH 4-derived carbonates of Monferrato (NW Italy): A solid evidence of fluid circulation in the sedimentary column. Mar. Geol., 265 (3-4), 167-184. - Colombi, A. & Pfeifer, H.R. (1986). Ferrogabbroic and basaltic metaeclogites from the Antrona mafic-ultramafic complex and the Centovalli-Locarno region (Italy and Southern Switzeland)-first results. Schweiz. mineral. petrogr. Mitt., 66, 99-110. - Compagnoni, R. (1977). The Sesia-Lanzo Zone: high pressure-low temperature metamorphism in the Austroalpine continental margin. Rend. Soc. It. Min. Petr., 33, 335-375. - Compagnoni, R. & Prato, R. (1969). Paramorfosi di cianite su sillimanite in scisti pregranitici del Massiccio del Gran Paradiso. Boll. Soc. Geol. It ., 88, 537-549. - Compagnoni, R. & Maffeo, B. (1973). Jadeite-bearing Metagranites l.s. and Related Rocks in the Mount Mucrone Area (Sesia-Lanzo Zone, Western Italian Alps). Schweiz. mineral. petrogr. Mitt., 53, 355-378. - Compagnoni, R., Elter, G. & Lombardo, B. (1974). Eterogeneità stratigrafica del complesso degli «gneiss minuti» nel massiccio cristallino del Gran Paradiso. Mem. Soc. Geol. It., 13 (1), 227-239. - Compagnoni, R. & Lombardo, B. (1974). The Alpine age of the Gran Paradiso eclogites. Rend. Soc. It. Min. Petr., 30, 223-237. - Compagnoni, R., Dal Piaz, G.V., Hunziker, J.C., Gosso, G., Lombardo, B. & Williams, P.F. (1977). The Sesia-Lanzo zone, a slice of continental crust with alpine high pressure-low temperature assemblages in the Western Italian Alps. Rend. Soc. It. Min. Petr., 33, 281-334. - Compagnoni, R. & Hirajima, T. (2001). Superzoned garnets in the coesite-bearing Brossasco-Isasca Unit, Dora-Maira Massif, Western Alps, and the origin of the whiteschists. Lithos, 57, 219-236. - Compagnoni, R., Rolfo, F., Groppo, C., Hirajima, T. & Turello, R. (2004). Mapping of Alpine rocks characterised by «HP» to «UHP» metamorphic overprint in the southern Dora-Maira Massif. In: G. Pasquaré & C. Venturini (Eds.) and G. Groppelli (Ass. Ed.) Mapping geology in Italy. APAT, Dipartimento Difesa del Suolo, Servizio Geologico d’Italia, Roma 2004 (2006), Map 34, 287-294. S.EL.CA., Firenze. - Compagnoni, R., Ferrando, S., Lombardo, B., Radulesco, N. & Rubatto, D. (2010). Paleo-European crust of the Italian Western Alps: Geological history of the Argentera Massif and comparison with Mont Blanc-Aiguilles Rouges and Maures-Tanneron Massifs. In: M. Beltrando, A. Peccerillo, M. Mattei, S. Conticelli & C. Doglioni (Eds.). J. Virtual Explorer , 36 (3), 1-25. 106 References

- Compagnoni, R., Rolfo, F., Groppo, C., Hirajima, T. & Turello, R. (2012). Geological map of the Ultra-High Pressure Brossasco-Isasca Unit (Western Alps, Italy). J. Maps, 8 (4), 465-472. - Compagnoni, R., Engi, M. & Regis, D. (2014). Valle d’Aosta section of the Sesia Zone: Multi-stage HP metamorphism and assembly of a rifted continental margin. 10 th Int. Eclogite Conference, Syn-Conf. Excursion, 5 Sept. 2013, GFT – Geol. Field Trips, 6 (1.2), 1-44. Doi: 10.3301/GFT.2014.02. - Cordey, F. &. Bailly, A. (2007). Alpine ocean seafloor spreading and onset of pelagic sedimentation: New radiolarian data from the Chenaillet-Montgenèvre ophiolite (French-Italian Alps). Geodinamica Acta, 20 (3), 131-138. - Cortesogno, L. & Haccard, D. (1979). Présentation des principales unités con- stitutives de la zone de Sestri-Voltaggio et de leurs relations structurales. Bull. Soc. Géol. Fr., 21, 7 (4), 379-388. - Cortesogno, L., Grandjacquet, C. & Haccard, D. (1979). Contribution à l’étude de la liaison Alpes-Apennins; évolution tectono-métamorphique des principaux ensembles ophiolitiques de Ligurie (Apennins du nord). Ofioliti, 4 (2), 157-172. - Cortesogno, L., Gianotti, R., Oxilia, M., Vanossi, M. & Vannucci, R. (1981). Genesi ed evoluzione dello zoccolo pre-Mesozoico di alcuni settori del Brianzonese Ligure Interno. Rend. Soc. It. Min. Petr., 38 (1), 219-260. - Cortesogno, L. & Haccard, D. (1984). Note illustrative alla carta geologica della Zona Sestri-Voltaggio. Mem. Soc. Geol. It., 28, 115-150. - Cortesogno, L., Dallagiovanna, G., Gaggero, L. & Vanossi, M. (1993). Elements of the Palaeozoic History of the Ligurian Alps. In: J.F. von Raumer & F. Neubauer (Eds.). Pre-Mesozoic geology in the Alps . Springer-Verlag, 257-277. - Covey, M. (1986). The evolution of foreland basins to steady state: Eviden- ce from the western Taiwan foreland basin. In: P.A., Allen & P. Homewood (Eds.). Foreland basins. Int. Ass. Sedim., Spec. Publ., 8, 77-90. - Crampton, S.L. & Allen, P.A. (1995). Recognition of forebulge unconformities associated with early stage foreland basin development: Example from the North Alpine Foreland Basin. Am. Ass. Petrol. Geol. Bull., 79, 1495-1514. - Crema, G., Dal Piaz, G.V., Merlo, C. & Zanella, E. (1971). Note illustrative della Carta Geologica d’Italia alla scala 1:100.000, Fogli 78-79-90 (Argentera- Dronero-Demonte), Serv. Geol. It., Roma, 93 p. - Crispini, L. & Capponi, G. (2001). Tectonic evolution of the Voltri Group and Sestri-Voltaggio Zone (southern limit of the NW Alps): A review. Ofioliti, 26 (2a), 161-164. - Crispini, L., Capponi, G. & Federico, L. (2009). Late orogenic transpressional tectonics in the «Ligurian Knot». It. J. Geosci., 128 (2), 433-441. References 107

- Cuffaro, M., Riguzzi, F., Scrocca, D., Antonioli, F., Carminati, E., Livani, M. & Doglioni, C. (2010) On the geodynamics of the northern Adriatic plate. Rend. Fis. Acc. Lincei, 21 (Suppl 1): S253-S279. Doi: 10.1007/s12210-010-0098-9. - Dalla, S., Rossi, M., Orlando, M., Visentin, C., Gelati, R., Gnaccolini, M., Papani, G., Belli, A., Biffi, U. & Catrullo, D. (1992). Late Eocene - Tortonian tectono-sedimentary evolution in the western part of the Padan basin (northern Italy). Paleontologia i Evoluciò, 24-25, 341-362. - Dal Piaz, G.V. (1964). II cristallino antico del versante meridionale del Monte Rosa. Paraderivati a prevalente metamorfismo alpino. Rend. Soc. It. Min. Petr., 20, 101-136. - Dal Piaz, G.V. (1966). Gneiss ghiandoni, marmi e anfiboliti antiche del ricoprimento Monte Rosa nell’alta valle d’Ayas. Boll. Soc. Geol. It., 85, 103-137. - Dal Piaz, G.V. (1971). Alcune considerazioni sulla genesi delle ofioliti piemontesi e dei giacimenti ad esse associati. Boll. Ass. Mineraria Subalpina, Torino , 8, 365-388. - Dal Piaz, G.V. (1974). Le métamorphisme de haute pression et basse tempéra- ture dans l’évolution structurale du bassin ophiolitique alpino-apenninique (2 e partie). Schweiz. mineral. petrogr. Mitt., 54, 399-424. - Dal Piaz, G.V. (1992a). Le Alpi dal M. Bianco al Lago Maggiore. Vol. 3/1. Guide Geologiche Regionali, Società Geologica Italiana, Roma, Be-Ma, Milano, 209 p. - Dal Piaz, G.V. (1992b). Le Alpi dal M. Bianco al Lago Maggiore. Vol. 3/2, 13 itinerari automobilistici e 97 escursioni a piedi. Guide Geologiche Regionali, Società Geologica Italiana, Roma, Be-Ma, Milano, 301 p. - Dal Piaz, G.V. (1999). The Austroalpine-Piedmont nappe stack and the puzzle of Alpine Tethys. Mem. Sci. Geol., 51, 155-176. - Dal Piaz, G.V. (2001). Geology of the Monte Rosa massif: historical review and personal comments. Schweiz. mineral. petrogr. Mitt., 81, 275-303. - Dal Piaz, G.V. (2010). The Italian Alps: A journey across two centuries of Alpine geology. J. Virtual Explorer , 36. Doi: 10.3809/jvirtex.2010.00234. - Dal Piaz, G.V. & Gatto, G.O. (1963). Considerazioni geologico-petrografiche sul versante meridionale del Monte Rosa. Accad. Naz. Lincei, Roma, Fis. Sci. Rend., 34, 190-194. - Dal Piaz, G.V., Gosso, G. & Martinotti, G. (1971). La II a Zona diorito-kinzigitica tra la Valsesia e la Valle d’Ayas (Alpi occidentali). Mem. Soc. Geol. It ., 10, 257-276, 1 carta 1:75.000. - Dal Piaz, G.V., Hunziker, J.C. & Martinotti, G. (1972). La zona Sesia-Lanzo e l’evoluzione tettonico metamorfica delle Alpi nord-occidentali interne. Mem. Soc. Geol. It., 11, 433-461. 108 References

- Dal Piaz, G.V., Venturelli, G. & Scolari, A. (1979). Calc-alkaline to ultrapotassic post-collisional volcanic activity in the internal Northwestern Alps. Mem. Sci. Geol. (Padova), 32, 1-16. - Dal Piaz, G.V. & Lombardo, B. (1986). Early Alpine eclogite metamorphism in the Penninic Monte Rosa-Gran Paradiso basement nappes of the northwestern Alps. Geol. Soc. Am. Mem., 164, 249-265. - Dal Piaz, G.V. & Gosso, G. (1994). Some remarks on evolution of the Alpine lithosphere. In: A. Montrasio & E. Sciesa (Eds.). Proc. Symp. CROP-Alpi Centrali, Sondrio, October 1993. Quaderni Geodinamica Alpina e Quaternaria (Milano), 2, 91-99. - Dal Piaz, G.V. & Martin, S. (1998). Evoluzione litosferica e magmatismo nel dominio Austro-Sudalpino dall’orogenesi varisica al rifting mesozoico. Mem. Soc. Geol. It., 53, 43-62. - Dal Piaz, G.V., Bistacchi, A. & Massironi, M. (2003). Geological outline of the Alps. Episodes, 26 (3), 175-180. - D’Amico, C. & Mottana, A. (1976). Hercynian plutonism in the Alps. A report 1973-74. Mem. Soc. Geol. It., 13, 49-118. - d’Atri, A. (1990a). Analisi sedimentologica, biostratigrafica e sequenziale della successione del Miocene inferiore tra le valli Lemme e Bormida di Spigno (margine sudorientale del Bacino terziario Ligure Piemontese). PhD Thesis, Università di Torino, 143 p. (unpubl.). - d’Atri, A. (1990b). Facies e sequenze deposizionali nella Formazione di Visone (Miocene inferiore, Bacino terziario ligure piemontese). Mem. Soc. Geol. It., 45, 723-729. - d’Atri, A. (1995). Biostratigrafia della Formazione di Visone (Miocene inferiore, Bacino terziario ligure-piemontese). Boll. Mus. Reg. Sci. Nat. (Torino) , 13, 345-375. - d’Atri, A. & Piazza, M. (1988). Facies a Corallinacee del Pliocene di Masserano (Biellese). Atti IV° Simposio Ecologia e Paleoecologia delle Comunità Bentoniche. Sorrento 1-5 Novembre 1988. Boll. Mus. Reg. Sci. Nat. (Torino) , 387-395. - d’Atri, A., Piana, F., Tallone, S., Bodrato, G. & Roz Gastaldi, M. (1997). Tettonica oligo-miocenica nell’Alto Monferrato (Bacino Terziario Piemontese) e nel settore nord-occidentale del Gruppo di Voltri (Acqui Terme, Cassinelle, AL). Atti Tic. Sci. Terra, Ser. Spec., 5, 85-100. - d’Atri A., Dela Pierre, F., Festa A., Piana, F. & Polino, R. (2002). Tettonica e sedimentazione nel retroforeland alpino, 81 a Riunione estiva, Soc. Geol ., It ., Torino, Italy , 1-114. References 109

- d’Atri, A., Piana, F., Barale, L., Bertok, C. & Martire, L. (2016a). Geological setting of the southern termination of Western Alps. Int. J. Earth Sci., 105, 1831-1858. - d’Atri, A., Irace, A., Piana, F., Tallone, S., Varrone, D., Bellino, L., Fioraso, G. Cadoppi, P., Fusetti, E., Morelli, M., Lanteri, L., Paro, L., Piccini, C., Trenkwalder, S. & Violanti, D. (2016b). Note illustrative della Carta Geologica d’Italia alla scala 1:50.000, Foglio 194, Acqui Terme . ISPRA, Roma, 229 p. - Davies, J.H. & von Blanckenburg, F. (1995). Slab breakoff: A model of lithosphere detachment and its test in the magmatism and deformation of collisional orogens. Earth Planet. Sci. Lett., 129, 85-102. - Debelmas, J. & Lemoine, M. (1957). Calcschistes Piemontais et terrains à faciès briançonnais dans les hautes vallées de la Maira et de la Varaita (Alpes cottiennes, Italie). C. R. somm. Soc. géol. Fr., 38-40. - Debelmas, J., Gidon, M. & Kerckhove, C. (1980). Idées actuelles sur les car- gneules alpines. Livre jubilaire Jacques Flandrin. Doc. Lab. Géologie Lyon, 4, 195-201. - Debenedetti, A. & Turi, B. (1975). Carniole della Valle d’Aosta: studio isoto- pico ed ipotesi genetica. Boll. Soc. Geol. It., 94, 1883-1894. - De Celles, P. (2012). Foreland basin systems revisited: Variations in response to tectonic settings. In: C. Busby & A. Azor (Eds.). Tectonics of Sedimentary Basins. Recent Advances. Blackwell, Chichester, UK, 405-426. - De Graciansky, P.C., Roberts, D.G. & Tricart, P. (2011). The Western Alps, from Rift to Passive Margin to Orogenic Belt: An Integrated Geoscience Overview. Developments in Earth Surface Processes , 14, 432 p., Amsterdam, Elsevier. - Delacou, B., Sue, C., Champagnac, J.D. & Burkhard, M. (2004). Present-day geodynamics in the bend of the western and central Alps as constrained by earthquake analysis. Geophys. J. Intern., 158, 753-774. - Dela Pierre, F., Clari, P.A., Cavagna, S. & Bicchi, E. (2002a). The Parona chaotic complex: A puzzling record of the Messinian (Late Miocene) events in Monferrato (NW Italy). Sed. Geol., 152, 289-311. - Dela Pierre, F., Piana, F. & Clari, P.A. (2002b). Il Monferrato. In: R. Polino (Ed.). Il sistema Alpino-Appenninico nel Cenozoico, Torino (Italy). Soc. Geol. It ., 81 a Riunione estiva, Guida alle escursioni, 116-128. - Dela Pierre, F., Piana, F., Boano, P., Fioraso, G., Forno, M.G., Polino, R. & Clari, P.A. (2003a). Carta Geologica d’Italia alla scala 1:50.000. Foglio 157 Trino. APAT, Agenzia per la Protezione dell’Ambiente e per i Servizi Tecnici - Dipartimento Difesa del Suolo, Roma. 110 References

- Dela Pierre, F., Piana, F., Fioraso, G., Boano, P., Bicchi, E., Forno, M.G., Violanti, D., Clari, P.A. & Polino, R. (2003b). Note illustrative della Carta Geologica d’Italia alla scala 1:50.000. Foglio 157 Trino. APAT, Roma , 147. - Dela Pierre, F., Festa, A. & Irace, A. (2007). Interaction of tectonic, sedimentary and diapiric processes in the origin of chaotic sediments: An example from the Messinian of the Torino Hill (Tertiary Piedmont Basin, NW Italy). Geol. Soc. Am. Bull., 119, 1107-1119. - Dela Pierre, F., Martire, L., Natalicchio, M., Clari, P.A. & Petrea, C. (2010). Authigenic carbonates in Upper Miocene sediments of the Tertiary Piedmont Basin (NW Italy): Vestiges of an ancient gas hydrate stability zone? Geol. Soc. Am. Bull., 122, 994-1010. - Dela Pierre, F., Bernardi, E., Cavagna, S., Clari, P.A., Gennari, R., Irace, A., Lozar, F., Lugli, S., Manzi, V., Natalicchio, M., Roveri, M. & Violanti, D. (2011). The record of the Messinian salinity crisis in the Tertiary Piedmont Basin (NW Italy): The Alba section revisited. Palaeogeography, Palaeoclimatology, Palaeoecology, 310, 238-355. - Dercourt, J., Gaetani, M., Vrielynck, B., Barrier, E., Biju-Duval, B., Brunet, M.F., Cadet, J.P., Crasquin, S. & Sandulescu, M. (2000 ). Atlas PeriTethys, Palaeogeographical Maps. CCGM/CGMW, Paris, I-XX, 269 p. - Dercourt, J., Zonenshain, L.P., Ricou, L.E. et al. (1986). Geological evolution of the Tethys belt from the Atlantic to the Pamirs since the Lias. Techtono physics, 123, 241-315. - Desmons, J., Compagnoni, R. & Cortesogno, L. (1999). Alpine metamorphism of the Western Alps: II. High-P/T and related pre-greenschist metamorphism. Schweiz. mineral. petrogr. Mitt., 79, 111-134. - Deville, E., Fudral, S., Lagabrielle, Y., Marthaler, M. & Sartori, M. (1992). From Oceanic closure to continental collision: A synthesis of the «Schistes lustrés» metamorphic complex of the Western Alps. Geol. Soc. Am. Bull., 104, 127-139. - Devoti, R., Esposito, A., Pietrantonio, G., Pisani, A.R. & Riguzzi, F. (2011). Evidence of large scale deformation patterns from GPS data in the Italian subduction boundary. Earth Planet. Sci. Lett., 311, 230-241. - De Wever, P. & Caby, R. (1981). Datation de la base des Schistes lustrés post- ophiolitiques par des radiolaires (Oxfordien supérieur-Kimméridgien moyen) dans les Alpes Cottiennes (Saint-Véran, France). C. R. Acad. Sci., Paris, 292, 467-472. - De Wever, P., Baumgartner, P.O. & Polino, R. (1987). Précision sur les datations de la base des Schistes lustrés post-ophiolitiques dans les Alpes cottiennes. C. R. Acad. Sci., Paris, 305 (2), 487-491. References 111

- Dewey, J.F. & Bird, J.M. (1970). Mountain belts and the new global tectonics. J. Geophys. Res., 75, 2625-2647. - Dewey, J.F., Pitman, W.C., Ryan, W.B.F. & Bonnin, J. (1973). Plate tectonics and the evolution of the Alpine system. Geol. Soc. Am. Bull., 84, 3137-3180. - Dewey, J.F., Helman, M.L., Turco, E., Hutton, D.H.W. & Knott, S.D. (1989). Kinematics of the western Mediterranean. In: M.P. Coward, D. Dietrich & R.G. Park (Eds.). Alpine tectonics. Geol. Soc. London, Spec. Publ., 45, 265-283. - Duggen, S., Hoernle, K.A., Boogard, P.V.D., Rupke, L. & Phipps Morgan, J. (2003). Deep roots of the Messinian salinity crisis. Nature, 422, 602-606. - Dumont, T., Lemoine, M. & Tricart, P. (1984). Tectonique synsédimentaire triasico-liasique et rifting tethysien dans l’unité piémontaise de Rochebrune au sud-est de Briançon. Bull. Soc. géol. Fr., 7, 26, 5, 921-933. - Dumont, T., Simon-Labric, T., Authemayou, C. & Heymes, T. (2011). Lateral termination of the north-directed Alpine orogeny and onset of westward esca- pe in the Western Alpine arc: Structural and sedimentary evidence from the external zone. Tectonics , 30, TC5006. - Ellenberger, F., Michard, A. & Sturani, C. (1964). Découverte d’ammonites et observations stratigraphiques dans les «Schistes lustrés» du Val Grana (Alpes Cottiennes). C. R. Acad. Sci. Paris, 259, 3047-3050. - Ellero, A. (2000). Assetto strutturale delle Unità Liguri Interne della Valpolcevera e dell’Alta Valle Scrivia (Appennino settentrionale). Boll. Soc. Geol. It., 119, 321-338. - Elter, G. (1971). Schistes Lustrés et ophiolites de la zone piémontaise entre Orco et Doire Baltée (Alpes Graies). Hypothèses sur l’origine des ophiolites. Géol. Alpine (Grenoble ), 47, 147-169. - Elter, P. (1973). Lineamenti tettonici ed evolutivi dell’Appennino settentrionale. In: B. Accordi (Ed.). Moderne vedute sulla geologia dell’Appennino. Accad. Naz. Lincei, Quaderni, 183, 97-118. - Elter, G., Elter, P., Sturani, C. & Weidmann, M. (1966). Sur la prolongation du domaine ligure de l’Apennin dans le Monferrat et les Alpes et sur l’origine de la Nappe de la Simme s.l. et des Préalpes romandes et chablaisiennes. Arch. Sci. Genève, 19, 279-377. - Elter P. & Pertusati P. (1973). Considerazioni sul limite Alpi-Appennino e sulle relazioni con l’arco delle Alpi Occidentali. Mem. Soc. Geol. It ., 12, 359-375. - Elter, F.M., Piccardo, G.B., Polino, R., Zanetti, A., Spagnolo, G., Poggi, E. & Balbi, P. (2005). Structural and compositional features of the Mt. Musinè peridotites (Lanzo Massif, western Alps, Italy). Ofioliti, 30, 161-173. - Engi, M., Berger, A. & Roselle, G. (2001a). The role of the tectonic accretionary channel in collisional orogeny. Geology, 29, 1143-1146. 112 References

- Engi, M., Scherrer, N.C. & Burri., T. (2001b). Metamorphic evolution of pelitic rocks of the Monte Rosa nappe: Constraints from petrology and single grain monazite age data. Schweiz. mineral. petrogr. Mitt., 81, 305-328. - Eva, E. & Solarino, S. (1998). Variations of stress directions in the western Alpine arc. Geophys. J. Int., 135, 438-448. - Falletti, P., Gelati, R. & Rogledi, S. (1995). Oligo-Miocene evolution of Monferrato and Langhe, related to deep structures. In: R. Polino & R. Sacchi (Eds.). Atti del convegno «Rapporti Alpi-Appennino e guide alle escursioni»: Peveragno (CN) 31 Maggio-1 Giugno 1994. Accad. Naz. Scienze, Scritti e Doc., XIV, 1-19. - Faure-Muret, A. (1955). Etudes gé ologiques sur le massif de l’Argentera- Mercantour et ses enveloppes sédimentaires. Mé m. Carte Géol. France, Paris, Imprimerie Nationale, 1-336. - Federico, L., Capponi, G., Crispini, L. & Scambelluri, M. (2004). Exhumation of alpine high-pressure rocks: Insights from petrology of eclogite clasts in the Tertiary Piedmontese basin (Ligurian Alps, Italy). Lithos, 74, 21-40. - Federico, L., Capponi, G., Crispini, L., Scambelluri, M. & Villa, I.M. (2005). 40 Ar/39 Ar dating of high-pressure rocks from the Ligurian Alps: Evidence for a continuous subduction-exhumation cycle. Earth Planet. Sci. Lett., 240, 668-680. - Ferrando S. (1999). Studio geologico-petrografico della zona del Canavese nel tratto compreso tra Issiglio e Sant’Anna Boschi (TO), con carta geologica alla scala 1:7.500, M. Sc. Thesis, Univ. of Torino, 178 p. (unpubl.) - Ferrando, S., Bernoulli, D. & Compagnoni, R. (2004). The Canavese zone (internal Western Alps): A distal margin of Adria. Schweiz. mineral. petrogr. Mitt., 84, 237-256. - Ferrando, S., Lombardo, B. & Compagnoni, R. (2008). Metamorphic history of HP mafic granulites from the Gesso-Stura Terrain (Argentera Massif, Western Alps, Italy). Eur. J. Mineral., 20, 777-790. - Ferrando, S., Frezzotti M.L., Petrelli M. & Compagnoni R. (2009). Metasomatism of continental crust during subduction: The UHP whiteschists from the Southern Dora-Maira Massif (Italian Western Alps). J. metam. Geol., 27, 739-756. - Ferrara, G. & Malaroda, R. (1969). Radiometric age of granitic rocks from the Argentera Massif (Maritime Alps). Boll. Soc. Geol. It., 88, 311-320. - Ferraris, C. & Compagnoni, R. (2003). Metamorphic evolution and significance of a serpentinized peridotite slice within the Eclogitic Micaschist Complex of the Sesia-zone (Western Alps - Italy). Schweiz. mineral. petrogr. Mitt ., 83, 3-13. References 113

- Ferrero, E., Merlino, B., Provera, A. & Martinetto, E. (2005). Associazione a molluschi marini e vegetali terrestri del Pliocene di Castellengo (Biella, Italia NW). Rend. Soc. Paleont. It., 2, 87-106. - Festa, A., Boano, P., Irace, A., Lucchesi, S., Forno, M. G., Dela Pierre, F., Fioraso, G. & Piana, F. (2009). Carta Geologica d’Italia alla scala 1:50.000. Foglio 156 Torino Est. APAT, Agenzia per la Protezione dell’Ambiente e per i Servizi Tecnici - Dipartimento Difesa del Suolo, Roma. - Festa, A., Fioraso, G., Bissacca, E. & Petrizzo, M.R. (2014). Geological map of the Villalvernia - Varzi Line between Scrivia and Curone valleys (NW Italy). J. Maps, 11 (1), 39-55. - Fettes, D. & Desmons, J. (2007 ). Metamorphic Rocks. A Classification and Glossary of Terms. Cambridge Univ. Press, 1-244. - Finetti, I.R. & Del Ben, A. (2000). Ionian opening, crustal stratigraphy and tectono-dynamics of the Pelagian Sea region from new CROP seismic data. Proc. Int.symp. on Geology of NW Libya, Tripoli, 2000. - Fiora, L., Piccardo, G.B. & Lanza, R. (1978). Osservazioni preliminari sulle oﬁoliti metamorﬁche del Monviso (Alpi Occidentali). Rend. Soc. It. Min. Petr., 34, 253-305. - Fioraso, G. & Spagnolo, G. (2009). I block stream del Massiccio Peridotitico di Lanzo (Alpi nord-occidentali). It. J. Quat. Sci., 22, 3-22. - Fioraso, G., Tarabra, M. & Negro, N. (2010). La deformazione gravitativa profonda di Sauze d’Oulx (Alpi Occidentali): analisi dei meccanismi deformativi in relazione all’evoluzione tardo quaternaria dell’alta Valle di Susa. It. J. Quat. Sci., 23 (1), 37-54. - Fioraso, G., Baggio, P., Bonadeo, L. & Brunamonte, F. (2011). Post-glacial evolution of gravitational slope deformations in the upper Susa and Chisone Valleys (Italian Western Alps). It. J. Quat. Sci., 24, 104-106. - Fioraso, G. & Baggio, P. (2013). Geological map of the Mount Ciantiplagna rock avalanche (Chisone Valley, Italian Western Alps). J. Maps, 9 (3), 336-342. - Fiorentini Potenza, M. (1959). Distribuzione delle principali facies petrografiche e della radioattività nel plutone «sienitico» di Biella (Valle del Cervo). Rend. Soc. It. Min. Petr., 1, 89-131. - Forcella, F. (1976). Avanzamento delle ricerche sull’assetto strutturale ed interpretazione geodinamica del Gruppo di Voltri. Ofioliti, 1, 243-254. - Forcella, F., Mottana, A. & Pasquarè, G. (1973). Il massiccio cristallino interno di Valosio. Mem. Soc. Geol. It., 12, 485-528. - Ford, M., Lickorish, W. & Kusznir, N.S. (1999). Tertiary foreland sedimentation in the Southern Subalpine Chains, SE France: A geodynamic appraisal. Basin Research , 11 (4), 315-336. 114 References

- Fornaciari, E., Iaccarino, S., Mazzei, R., Rio, D., Salvatorini, G., Bossio, A. & Monteforti, B. (1997a). Calcareous plankton biostratigraphy of the Langhian historical stratotype. In: A. Montanari, G.S. Odin & R. Coccioni (Eds.). Miocene stratigraphy. An integrated approach. Elsevier , 89-96. - Fornaciari, E., Rio, D., Ghibaudo, G., Massari, F. & Iaccarino, S. (1997b). Calcareous plankton biostratigraphy of the Serravallian (Middle Miocene) stratotype section (Piedmont Tertiary Basin, NW Italy). Mem. Soc. Geol. It ., 49, 127-144. - Fornasero, D. (1978). Studio geologico-petrografico dell’aureola termometa- morfica del Plutone della Valle del Cervo (Biella). MSc. Thesis, University of Turin , 186 p. (unpubl). - Forno, M.G. (1982). Studio geologico dell’Altopiano di Poirino. Geogr. Fis. Din. Quat., 5, 129-162. - Forno, M.G., Gattiglio, M., Comina, C., Barbero, D., Bertini, A., Doglione, A., Gianotti, F., Irace, A., Martinetto, E., Mottura, A. & Sala, B. (2015). Stratigraphic and tectonic notes on the Villafranca d’Asti succession in type-area and Castelnuovo Don Bosco sector (Asti Reliefs, Piedmont). Alp. Mediterr. Quat., 28, 5-27. - Fountain, D.M. (1976). The Ivrea-Verbano and Strona-Ceneri Zones, Northern Italy: A cross section of the continental crust - New evidence from seismic ve- locities of rock samples. Tectonophysics , 33, 145-165. - Franchi, S. (1897). Appunti geologici e petrografici sui monti di Bussoleno nel versante destro della Dora Riparia. Boll. R. Comit. Geol. It., 28, 3-46. - Franchi, S. & Novarese, V. (1895). Appunti geologici e petrografici sui dintor- ni di Pinerolo. Boll. R. Comit. Geol. It., 26, 385-429. - Franke, D. (2012). Rifting, lithosphere breakup and volcanism: Comparison of magma-poor and volcanic rifted margins. Mar. Petrol. Geol., 43, 63-87. - Frey, M., Hunziker, J.C., Frank, W., Bocquet, J., Dal Piaz, G.V, Jäger, R.E. & Niggli, E. (1974). Alpine metamorphism of the Alps. A review. Schweiz. mineral. petrogr. Mitt., 54, 247-290. - Frisch, W. (1979). Tectonic progradation and plate tectonic evolution of the Alps. Tectonophysics , 60, 121-139. - Friz, C. & Govi, M. (1963). Osservazioni geologiche preliminari sulla zona a Nord-Ovest di Gattinara (Vercelli). Rend. Accad. Naz. Lincei, Ser. 8, 34, 199-203. - Froitzheim, N. (2001). Origin of the Monte Rosa nappe in the Pennine Alps. A new working hypothesis. Geol. Soc. Amer. Bull., 113, 604-614. - Froitzheim, N., Schmid, S.M., Frey, M. (1996). Mesozoic paleogeography and References 115

the timing of eclogite-facies metamorphism in the Alps: A working hypothesis. Eclogae geol. Helv., 89, 81-11. - Froitzheim, N., Plašienka, D. & Schuster, R. (2008). Alpine tectonics of the Alps and Western Carpathians. In: T. McCann (Ed.). The geology of Central Europe, Vol. 2: Mesozoic and Cenozoic. Geol. Soc. London, Spec. Publ., 1141-1232. - Fudral S., Deville E., Nicoud G., Pognante U., Guillot, P.L. & Jaillard, E. (1994a). Notice explicative de la feuille 776 Lanslebourg - Mont d’Ambin . Carte Géologique de la France à 1:50.000, 96 p. - Fudral, S., Deville, E., Pognante, U., Gay, M., Fregolent, G., Lorenzoni, S., Robert, D., Nicoud, G., Blake, C., Jayko, A., Jaillard, E., Bertrand, J.M., Forno, M.G. & Massaza, G. (1994b). Carte Géologique de la France à 1:50.000 , feuille 776 Lanslebourg - Mont d’Ambin. - Gabudianu Radulescu, I., Lombardo, B. & Compagnoni, R. (2011). Polymetamorphic history of a relict Variscan hornfels from central Gran Paradiso Massif (Western Alps, Italy): A microstructural study and ther- modynamic modelling. J. metam. Geol., 29, 851-874. - Gaetani, M. (2010). From Permian to Cretaceous: Adria as pivotal between extensions and rotations of Tethys and Atlantic Oceans. In: M. Beltrando, A. Peccerillo, M. Mattei, S. Conticelli & C. Doglioni (Eds.). The Geology of Italy: tectonics and life along plate margins, J. Virtual Explorer , 36, paper 6. Doi: 10.3809/jvirtex.2010.00235. - Gaggero, L., Cortesogno, L. & Bertrand, J.M. (2004). The pre-Namurian basement of the Ligurian Alps: A review of the lithostratigraphy, pre-Alpi- ne metamorphic evolution, and regional comparisons. Period. Mineral., 73, 85-96. - Gandin, A., Tongiorgi, M., Rau, A. & Virgili, C. (1982). Some Examples of the Middle-Triassic Marine transgression in South-Western Mediterranean Europe. Geol. Rundsch., 71, 881-894. - Ganne, J., Bussy, F. & Vidal, O. (2003). Multi-stage garnet in the internal Briançonnais basements (Ambin and South Vanoise massifs): New petrological constraints on the blueschist-facies metamorphism in the Western Alps and tectonic implications. J. Petrol ., 44, 1281-1308. - Ganne, J., Bertrand, J.M. & Fudral, S. (2004). Geometry and kinematics of early Alpine nappes in a Briançonnais basement (Ambin Massif, Western Alps). C. R. Geosci., 336, 1219-1226. - Gasco, I., Gattiglio, M. & Borghi, A. (2009). Structural evolution of different tectonic units across the Austroalpine-Penninic boundary in the middle Orco Valley (Western Italian Alps). J. Struct. Geol., 31, 301-314. 116 References

- Gasco, I. & Gattiglio, M. (2011). Geological map of the middle Orco Valley, Western Italian Alps. J. Maps, 7(1), 463-477. - Gay, M. (1972a). Le massif d’Ambin et son cadre de Schistes lustrés (Alpes franco-italiennes). Evolution métamorphique. Arch. Sci. Genève , 25 (1), 5-100. - Gay, M. (1972b). Le massif d’Ambin et son cadre de Schistes lustrés (Alpes franco-italiennes). Évolution structurale. Arch. Sci. Genève , 25 (2), 165-214. - Gebauer, D., Schertl, H.-P., Brix, M. & Schreyer, W. (1997). 35 Ma old ultra- high-pressure metamorphism and evidence for very rapid exhumation in the Dora Maira Massif, Western Alps. Lithos, 41, 5-24. - Gelati, R. & Pasquaré, G. (1970). Interpretazione geologica del limite Alpi- Appennini in Liguria. Riv. It. Paleont. Strat ., 76 (4), 513-578. - Gelati, R. & Gnaccolini, M. (1982). Evoluzione tettonico-sedimentaria della zona limite tra Alpi ed Appennino tra l’inizio dell’Oligocene ed il Miocene medio. Mem. Soc. Geol. It., 24, 183-191. - Gelati, R., Gnaccolini, M., Falletti, P. & Citrullo, D. (1993). Stratigrafia sequenziale della successione Oligo-Miocenica delle Langhe, Bacino terziario ligure-piemontese. Riv. It. Paleont. Strat., 98, 425-452. - Gelati, R. & Gnaccolini, M. (1998). Synsedimentary tectonics and sedimentation in the Tertiary Piedmont Basin, Northwestern Italy. Riv. It. Paleont. Strat. , 104 (2), 193-214. - Gelati, R. & Gnaccolini, M. (2003). Genesis and evolution of the Langhe basin, with emphasis on the latest Oligocene- Earliest Miocene and Serravallian. Atti Tic. Sci. Terra, 44, 3-18. - Gelati, R., Gnaccolini, M., Granata, P., Masi, M., Piana, F., Polino, R., Brovero, M., Drago, D., Fioraso, G., Sorzana, F. & Fontan, D. (2010a). Carta Geologica d’Italia alla scala 1:50.000. Foglio 211, Dego. ISPRA - Istituto Superiore per la Protezione e la Ricerca Ambientale, Roma. - Gelati, R., Gnaccolini, M., Polino, R., Mosca, P., Piana, F., Morelli, M. & Fioraso, G. (2010b) - Note illustrative della Carta Geologica d’Italia alla scala 1:50.000. Foglio 211, Dego. ISPRA - Istituto Superiore per la Protezione e la Ricerca Ambientale, Roma, 124 p. - Gennari, R., Iaccarino, S.M., Di Stefano, A., Sturiale, G., Cipollari, P., Manzi, V., Roveri, M. & Cosentino, D. (2008). The Messinian-Zanclean boundary in the Northern Apennines. In: V. Manzi, S.M. Iaccarino, S. Lugli & M. Roveri (Eds.). The Messinian salinity crisis revisited. II, stratigraphy, 5, 309-325. - Gerlach, H. (1869). Die Penninischen Alpen. N. Denkschr. Schweiz. Natf. Ges., 23, 132 p. - Gerlach, H. (1871). Das Südwestliche Wallis, Beiträge geol. Karte Schweiz, 9, 175 p. References 117

- Germani, D., Angiolini, L. & Cita, M.B. (2003). Guida italiana alla classifica- zione e alla terminologia stratigrafica. APAT, Dipartimento Difesa del Suolo, Quaderni, serie III, vol. 9, 155 p. SELCA, Firenze. - Ghibaudo, G., Clari, P.A. & Perello, M. (1985). Litostratigrafia, sedimentolo- gia ed evoluzione tettonico-sedimentaria dei depositi miocenici del margine sud-orientale del Bacino terziario ligure-piemontese (Valli Borbera, Scrivia e Lemme). Boll. Soc. Geol. It., 104, 349-397. - Ghibaudo, G., Massari, F. & Chiambretti, I. (2010a). Carta Geologica delle Langhe Meridionali tra le Valli Bormida di Spigno e Uzzone (Bacino Terziario Piemontese), Scala 1:20.000. J. Medit. Earth Sci., 6 (2014). - Ghibaudo, G., Massari, F., Chiambretti, I. & d’Atri, A. (2010b). Carta Geologica dell’area Roccaverano-Merana-Valle Bormida di Spigno (Bacino Terziario Piemontese), Scala 1:16.500. J. Medit. Earth Sci., 6 (2014). - Ghibaudo, G., Massari, F. & Chiambretti, I. (2014). Oligo-Miocene Tectono -sedimentary evolution of the Langhe Sub-basin: From continental to basinal setting (Tertiary Piedmont Basin-Northwestern Italy). J. Medit. Earth Sci ., 6, 53-144. - Ghielmi, M., Minervini, M., Nini, C., Rogledi, S., Rossi, M. & Vignolo, A. (2010). Sedimentary and tectonic evolution in the eastern Po-Plain and northern Adriatic Sea area from Messinian to Middle Pleistocene (Italy). In: F.P. Sassi, G. Dal Piaz & C. Doglioni (Eds.). Nature and Geodynamics of the Northern Adriatic Lithosphere. Rend. Fis. Acc. Lincei, 21 (1), 131-166. - Ghielmi, M., Minervini, M., Nini, C., Rogledi, S. & Rossi, M. (2013). Late Miocene-Middle Pleistocene sequences in the Po Plain - Northern Adriatic Sea (Italy): The stratigraphic record of modification phases affecting a complex foreland basin. Mar. Petrol. Geol., 42 (C), 50-81. - Giammarino, S., Fanucci, F., Orezzi, S., Rosti, D. & Morelli, D. (2010). Note illustrative della Carta Geologica d’Italia alla scala 1:50.000. Foglio 258- 271 Sanremo. Regione Liguria, Dipartimento Ambiente Servizio Assetto del Territorio, Genova , 130 p. - Gianotti, F., Forno, M.G., Ivy-Ochs, S. & Kubik, P.W. (2008). New chronological and stratigraphical data on the Ivrea amphitheatre (Piedmont, NW Italy). Quaternary Intern., 190, 123-135. - Gianotti, F., Forno, M.G., Ivy-Ochs, S., Monegato, G., Pini, R. & Ravazzi, C. (2015). Stratigraphy of the Ivrea morainic amphitheatre (NW Italy): An updated synthesis. Alp. Mediterr. Quat., 28 (1), 29-58. - Gidon, M. (1972). Les chaînons briançonnais et subbriançonnais de la rive gauche de la Stura entre Bersezio et le Val de l’Arma (province de Cuneo, Italie). Géol. Alpine (Grenoble), 48, 87-120. - Gidon, M., Kerckhove, C., Michard, A., Tricart, R., Gotteland, R., Gout, C., 118 References

Leblanc, D., Lefèvre R., Le Guernic, J., Mégard-Galli, J. & Michel-Noël, G. (1994). Carte géologique de France 1/50 000, feuille Aiguille de Chambeyron. Notice explicative, 90 p., Bur. Rech. Géol. Min. Orléans. - Giglia, G., Capponi, G., Crispini, L. & Piazza, M. (1996). Dynamics and seismotectonics of the western-Alpine arc. Tectonophysics , 267, 143-175. - Giraudi, C. (2014). Quaternary studies as a tool to validate seismic hazard po- tential of tectonic structures: The case of the Monferrato Thrust Front (Vercelli Plain, NW Italy). Alp. Mediterr. Quat., 27 (1), 5-28. - Giraudi, C. (2015). Quaternary evolution of the plain between Casale Monferrato and Valenza: Implications for the tectonics of the Monferrato Thrust Front (Piedmont, NW Italy). Alp. Mediterr. Quat., 28 (1), 71-92. - Gnaccolini, M. (1968). Il bacino delle Langhe durante il Miocene. Riv. It. Paleont. Strat., 74 (1), 133-142. - Gnaccolini, M. & Rossi, P.M. (1994). Sequenze deposizionali e composizione delle arenarie nel Bacino Terziario ligure-piemontese: osservazioni preliminari. Atti Tic. Sci. Terra, 37, 3-15. - Gosso, G., Brizio, D., Deregibus, C., Eusebio, A., Gallo, M., Rattalino, E., Rossi, F. & Tosetto, S. (1983). Due cinematiche possibili per la coppia di falde Brianzonese ligure – Flysch a Elmintoidi. Mem. Soc. Geol. It., 26, 463-472. - Gouffon, Y., Burri, M. (1997). Les nappes des Pontis, de Siviez-Mischabel et du Mont Fort dans les vallées de Bagnes, d’Entremont (Valais, Suisse) et d’Aoste (Italie). Eclogae geol. Helv., 90, 29-41. - Govi, M. (1977). Carta geologica del distretto vulcanico ad oriente della bassa Val Sesia. Scala 1:25.000. Centro Studi sui problemi dell’Orogeno delle Alpi Occidentali. CNR, Torino. - Groppo, C., Lombardo, B., Castelli, D. & Compagnoni, R. (2007). Exhumation history of the UHPM Brossasco-Isasca unit, Dora-Maira massif, as inferred from a phengite-amphibole eclogite. Int. Geol. Review, 49, 142-168. - Guillaume, A. (1980). Tectonophysics of the Western Alps. Eclogae geol. Helv., 73, 425-436. - Handy, M.R. (1987). The structure, age and kinematics of the Pogallo fault zone, southern Alps, northwestern Italy. Eclogae geol. Helv., 80, 593-632. - Handy, M.R., Franz, L., Heller, F., Janott, B. & Zurbriggen, R. (1999). Multistage exhumation and accretion of the continental crust (Ivrea crustal section, Italy and Switzerland). Tectonics , 18, 1154-1177. - Handy, M.R., Schmid, S.M., Bousquet, R., Kissling, E. & Bernoulli, D. (2010). Reconciling plate-tectonic reconstructions of Alpine Tethys with the geological-geophysical record of spreading and subduction in the Alps. Earth- Sci. Reviews, 102, 121-158. References 119

- Hedberg, H.D. (Ed.) (1976). International Stratigraphic Guide: A Guide to Stratigraphic Classification, Terminology, and Procedure . Wiley & Sons, New York. - Hermann, F. (1937). Carta geologica delle Alpi nord-occidentali alla scala 1:200.000, con note illustrative. Tipografia Allegretti di Campi, Milano , 24 p. - Hölker, A.B. (2001). Seismic structure and response of ocean-continent transition zones in magma-poor rifted continental margins. PhD Thesis, ETH No. 14455, Zürich, Switzerland. - Hoogerduijn Strating, E.H. (1994). Extensional faulting in an intra-oceanic subduction complex: working hypothesis for the Palaeogene of the Alps- Apennine system. Tectonophysics , 238, 255-273. - Horrenberg, J.C., Michard, A. & Werner, P. (1978). Le couloir de décrochement de Bersezio en Haute Stura, Alpes externes, Italie. Structure de compression sub-méridienne. Sci. Geol. Bull., 31, 15-20. - Hunziker, J.C. (1970). Polymetamorphism in the Monte Rosa, Western Alps. Eclogae geol. Helv., 63, 151-161. - Hunziker, J.C. & Zingg, A. (1980). Lower Paleozoic amphibolite to granulite facies metamorphism in the Ivrea Zone (Southern Alps, Northern Italy). Schweiz. mineral. petrogr. Mitt., 60, 181-213. - Hunziker, J.C., Desmons, J. & Hurford, A.J. (1992). Thirty-two years of geochronological work in the central and Western Alps: A review on seven maps. Mém. Géologie (Lausanne), 13, 1-59. - Hurford, A.J. (1986). Cooling and uplift patterns in the Lepontine Alps, south- central Switzerland, and an age of vertical movement on the Insubric fault line. Contrib. Mineral. Petrol ., 93, 413-427. - Iaccarino, S., Castradori, D., Cita, M.B., Di Stefano, E., Gaboardi, S., McKenzie, J.A., Spezzaferri, S. & Sprovieri, R. (1999). The Miocene/ Pliocene boundary and the significance of the earliest Pliocene flooding in the Mediterranean. Mem. Soc. Geol. It., 54, 109-131. - Irace, A., Dela Pierre, F. & Clari P.A. (2005). «Normal» and «chaotic» deposits in the Messinian Gessoso-Solfifera Fm. at the north-eastern border of the Langhe domain (Tertiary Piedmont basin). Mem. Soc. Geol. It., 4, 77-85. - Irace, A., Clemente, P., Natalicchio, M., Ossella, L., Trenkwalder, S., De Luca, D.A., Mosca, P., Piana, F., Polino, R. & Violanti, D. (2009). Geologia e idro- stratigrafia profonda della Pianura Padana occidentale. Edizioni La Nuova Lito, Firenze, 135 p. - Irace, A., Clemente, P., Piana, F., De Luca, D.A., Polino, R., Violanti, D., Mosca, P., Trenkwalder, S., Natalicchio, M., Ossella, L., Governa, M. & Petricig, M. (2010). Hydrostratigraphy of the late Messinian-Quaternary 120 References

basins in the southern Piedmont (northwestern Italy). Mem. descr. Carta Geol. It ., 90, 133-152. - Irace, A., Monegato, G., Tema, E., Martinetto, E., Gianolla, D., Vassio, E., Bellino, L. & Violanti, D. (2017). Unconformity-bounded stratigraphy in the Plio-Pleistocene continental record: New insights from the Alessandria Basin (NW Italy). Geol. J., 52, 177-206. - Jeanbourquin, P. (1994). The lower Penninic nappes in the western Alps: The link between Helvetic and Penninic. J. Struct. Geol., 16, 895-898. - Joos, M.G. (1969). Zur Geologie und Petrographie der Monte Giove- Gebirgsgruppe im östlichen Simplon-Gebiet (Novara, Italia). Schweiz. mineral. petrogr. Mitt., 49, 277-323. - Jordan, T.E. & Flemings, P.B. (1991). Large-scale stratigraphic architecture, eustatic variation, and unsteady tectonism: A theoretical evaluation. J. Geophys. Res., 96, 6681-6699. - Kapferer, N., Mercolli, I., Berger, A., Ovtcharova, M. & Fügenschuh, B. (2012). Dating emplacement and evolution of the orogenic magmatism in the internal Western Alps: 2. The Biella Volcanic Suite. Swiss J. Geosci ., 105 (1), 67-84. - Keller, L.M. & Schmid, S.M. (2001). On the kinematics of shearing near the top of the Monte Rosa nappe and the nature of the Furgg zone in Val Loranco (Antrona valley, N. Italy): tectonometamorphic and paleogeographical consequences. Schweiz. mineral. petrogr. Mitt., 81 (3), 347-367. - Keller, L.M., Hess, M., Fügenschuh, B. & Schmid, S.M. (2005). Structural and metamorphic evolution SW of the Simplon line. Eclogae geol. Helv ., 98, 19-49. - Kerckhove, C. (1969). La «zone du flysch» dans les nappes de l’Embrunais- Ubaye (Alpes occidentales). Géol. Alpine (Grenoble ), 45, 5-204. - Kerckhove, C. (1980). Carte Géologique de la France à 1/250.000. Feuille 35 «Gap». Bur. Rech. Géol. Min., Orléans. - Kienast, J.R., Lombardo, B., Biino, G. & Pinardon, J.L. (1991). Petrology of very high-pressure eclogitic rocks from Brossasco-Isasca complex, Dora- Maira Massif, Italian western Alps. J. metam. Geol., 9, 19-34. - Kissling, E. (1984). Three-dimensional gravity model of the northern Ivrea- Verbano Zone. In: J.-J. Wagner & St. Mueller (Eds.). Geomagnetic and gravimetric studies of the Ivrea Zone. Geophysique, 21, Materiaux pour la Géologie de la Suisse, 53-61. - Klaper, E.M. (1990). A discussion of contour maps in the Toce subdome of the Penninic realm (Switzerland, Italy). Schweiz. mineral. petrogr. Mitt ., 70, 349-360. - Klein, J.A. (1978). Post-nappe folding southeast of the Mischabelrü ckfalte (Pennine Alps) and some aspects of the associated metamorphism. Leidse Geol. Meded., 51, 233-312. References 121

- Krummenacher, D. & Evernden, J. (1960). Détermination d’âge isotopique sur quelques roches des Alpes par la méthode K-Ar. Schweiz. mineral. petrogr. Mitt., 40, 267-277. - Kuenen, H. (1925). The porphyry district of Lugano West of the Valganna. Leidse Geol. Meded., 1, 127-185 - Lagabrielle, Y., Nervo, R., Polino, R. & Dutto, F. (1982). Sedimentary cover of some ophiolites of the Cottian Alps. Ofioliti, 2-3, 339-350. - Lagabrielle, Y. & Polino, R. (1988). Un schéma structural du domaine des Schistes lustrés ophiolitifères au nord-ouest du massif du Mont Viso (Alpes Sud Occidentales) et ses implications. C.R. Acad. Sci. Paris , Série II, 306, 921-928. - Lagabrielle, Y., Fudral, S. & Kienast, J.-R. (1989). La couverture océanique des ultrabasites de Lanzo (Alpes occidentales): arguments lithostratigraphiques et pétrologiques. Geodin. Acta (Paris), 4, 43-55. - Lagabrielle, Y., Labaume, P. & de Saint Blanquat, M. (2010). Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): Insights from the geological setting of the lherzolite bodies. Tectonics , 29, TC4012. Doi: 10.1029/2009TC002588.2010. - Lange, S., Nasdala, L., Poller, U., Baumgartner, L.P. & Todt, W. (2000). Crystallization age and metamorphism of the Monte Rosa Granite, Western Alps. 17 th Swiss Tectonic Studies Group Meeting, Zürich, Abs. volume, 51 p. - Lanteaume, M. (1968). Contribution à l’étude géologique des Alpes Maritimes franco-italiennes. Mém. Serv. Carte Géol. Fr. (et CNRS), 405 p. - Lanteaume, M., Radulesco, N., Gravos, M., Féraud, J., Faure-Muret, A., Haccard, D., Villey, M., Lecanu, J.P., Dufay, D., Gigot, P., Vigne, M.F., Aguinet, R., Vaslet, D. & Campredon, R. (1990). Notice explicative, Carte géologique de France 1/50.000, feuille Viève-Tende. Bur. Rech. Géol. Min. , Orléans, 129 p. - Lanza, R. (1977). Palaeomagnetic data from the andesitic and lamprophyric dykes of the Sesia-Lanzo Zone (Western Alps). Schweiz. mineral. petrogr. Mitt., 57, 281-290. - Lanza, R. (1984). Possibili relazioni tra corpo d’Ivrea e unità strutturali alpine. Mem. Soc. Geol. It., 29, 25-33. - Lardeaux, J.M. & Spalla, M.I. (1990). Tectonic significance of P–T–t paths in metamorphic rocks: Examples from ancient and modern orogenic belts. Mem. Soc. Geol. It., 45, 51-69. - Lardeaux, J.M., Schwartz, S., Tricart, P., Paul, A., Guillot, S., Béthoux, N. & Masson, F. (2006). A crustal-scale cross-section of the south-western Alps combining geophysical and geological imagery. Terra Nova , 18, 412-422. - Larroque, C., Delouis, B., Godel, B. & Nocquet, J. M. (2009). Active 122 References

deformation at the southwestern Alps-Ligurian basin junction (France-Italy boundary): Evidence for recent change from compression to extension in the Argentera massif. Tectonophysics , 467, 22-34. - Laubscher, H.P. (1971). The large scale kinematics of the western Alps and the northern Apennines and its palinspastic implications. Am. J. Sci., 271, 193-226. - Laubscher, H.P. (1988). The arcs of the Western Alps and the Northern Apennines: An updated review. Tectonophysics , 146, 67-78. - Laubscher, H.P. (1991). The arcs of western Alps today. Eclogae geol. Helv., 84, 613-651. - Laubscher, H.P. & Bernoulli, D. (1977). Mediterranean and Tethys. In: A.E.M. Nairn, W.H. Kanes & F.G. Stehli (Eds.). The ocean Basins and Margins, 4A, Chapt. 1, 1-28. Plenum Publishing Corporation, New York. - Laubscher, H.P., Biella, G.C., Cassinis, R., Gelati, R., Lozej, A., Scarascia, S. & Tabacco, I. (1992). The collisional knot in Liguria. Geol. Rundsch., 81, 275-289. - Le Bayon, B. & Ballèvre, M. (2004). Field and petrological evidence for a Late Palaeozoic (Upper Carboniferous-Permian) age of the Erfaulet orthogneiss (Gran Paradiso, Western Alps). C. R. Geoscience, 336, 1079-1089. - Le Bayon, B. & Ballèvre, M. (2006). Deformation history of a subducted continental crust (Gran Paradiso, Western Alps): Continuing crustal shortening during exhumation. J. Struct. Geol., 28, 793-815. - Le Bayon, B., Pitra, P., Ballèvre, M. & Bohn, M. (2006). Reconstructing P–T paths during continental collision using multi-stage garnet (Gran Paradiso nappe, Western Alps). J. metam. Geol., 24, 477-496. - Le Bayon, R., de Capitani, C. & Frey, M. (2006). Modelling phase-assemblage

diagrams for magnesian metapelites in the system K2O–FeO–MgO–Al2O3–

SiO2–H 2O: Geodynamic consequences for the Monte Rosa nappe, Western Alps. Contrib. Mineral. Petrol ., 151, 395-412. - Lefèvre, R. (1984). Les nappes briançonnaises internes entre Maira et Grana (Alpes cottiennes méridionales). Géol. Alpine (Grenoble ), 60, 27-36. - Lefèvre, R. & Michard, A. (1976). Les nappes briançonnaises internes et ultra- briançonnaises de la bande d’Acceglio (Alpes franco-italiennes); une étude structurale et pétrographique dans le faciès des schistes bleus à jadéite. Sci. géol. Bull., 29, 183-222. - Lemoine, M. (1967). Brèches sédimentaires marines à la frontière entre les domaines briançonnais et Piémontais dans les Alpes occidentales. Geol. Rundsch., 56, 320-335. References 123

- Lemoine, M. (1971). Données nouvelles sur la Série du Gondran près Briançon (Alpes Cottiennes). Réflexions sur les problèmes stratigraphique et paléogéo- graphique de la zone piémontaise. Géol. Alpine (Grenoble ), 47, 181-201. - Lemoine, M. (1980). Serpentinites, gabbros and ophicalcites in the Piedmont- Ligurian domain of the Western Alps: Possible indicator of oceanic fracture zones and of associated serpentinite protrusion in the Jurassic Cretaceous Tethys. Arch. Sci. Genève , 33, 103-115. - Lemoine, M. & Tricart, P. (1979). Une partie des Schistes Lustrés et des ophiolites du Queyras (Alpes occidentales françaises) résultent-ils de sédimentation et d’écroulement au pied d’un escarpement de faille océanique? C.R. Acad. Sci. Paris, 288, 1655-1658. - Lemoine, M. & Tricart, P. (1986). Les Schistes lustrés piémontais des Alpes Occidentales: approche stratigraphique, structurale et sédimentologique. Eclogae geol. Helv., 79, 271-294. - Lemoine, M., Bas, T., Arnaud-Vanneau, A., Arnaud, A., Dumont, T., Gidon, M., Bourbon, M., de Graciansky, P.C., Rudkiewicz, J.L., Mégard-Galli, J. & Tricart, P. (1986). The continental margin of the Mesozoic Tethys in the Western Alps. Mar. Petrol. Geol., 3, 179-199 - Lensch, G. (1968). Die Ultramafitite der Zone von Ivrea und ihre geologische Interpretation. Schweiz. mineral. petrogr. Mitt., 48, 91-102. - Lensch, G. (1971). Die Ultramafitite der Zone von Ivrea. Annales Universitatis Saraviensis, 9, 5-146. - Le Pichon, X. (1968). Sea-floor spreading and continental drift. J. Geophys. Res., 73(12), 3661-3697. - Lewis, A.D. & Snewing, J.D. (1980). The Montgenèvre ophiolite (Hautes- Alpes, France): Metamorphism and trace element geochemistry of the volcanic sequence. Chem. Geol., 28, 291-306. - Liati, A., Gebauer, D., Froitzheim, N. & Fanning, C.M. (2001). U-Pb SHRIMP geochronology of an amphibolitized eclogite and an orthogneiss from the Furgg zone (Western Alps) and implications for its geodynamic evolution. Schweiz. mineral. petrogr. Mitt., 81, 379-393. - Liati, A., Froitzheim, N. & Fanning, C.M. (2005). Jurassic ophiolites within the Valais domain of the Western and Central Alps: Geochronological evidence for re-rifting of oceanic crust. Contrib. Mineral. Petrol ., 149, 446-461. - Liou, J.G., Maruyama, S. & Cho, M. (1985). Phase equilibria and mineral parageneses of metabasites in low-grade metamorphism. Miner. Mag ., 49, 321-333. - Lofi, J., Sage, F., Déverchère, J., Loncke, L., Maillard, A., Gaullier, V., Thinon, 124 References

I., Gillet, H., Guennoc, P. & Gorini, Ch. (2011). Refining our knowledge of the Messinian salinity crisis in the offshore domain through multi-site seismic analysis. Bull. Soc. géol. Fr., 182, 163-180. - Lombardo, B., Nervo, R., Compagnoni, R., Messiga, B., Kienast, J.R., Mevel, C. & Lanza R. (1978). Osservazioni preliminari sulle ofioliti metamorfiche del Monviso (Alpi Occidentali). Rend. Soc. It. Mineral. Petrol ., 34, 253-305. - Lombardo, B., Nervo, R., Compagnoni, R., Messiga, B., Kienast, J. R., Mevel, M, Martin, S., Tartarotti, P. & Dal Piaz, G. V. (1994). The Mesozoic ophiolites of the Alps: A review. Boll. Geofis. Teor. Appl. , 36, 175-219. - Lombardo, V., Piana, F., Fioraso, G., Irace, A., Mimmo, D., Mosca, P., Tallone S., Barale, L., Morelli, M. & Giardino, M. (2016). The Classification Scheme of the Piemonte Geological Map and the «OntoGeonous» initiative. Rend. Online Soc. Geol. It., 39, 117-120. - Lombardo, V., Piana, F. & Mimmo, D. (2018). Semantics-informed geological maps: Conceptual modeling and knowledge encoding. Comput. Geosci., 116, 12-22. - Lorenz, C. (1968). Contribution à l’é tude stratigraphique de l’Oligocène e du Miocène inférieur des confins liguro-piémontais (Italie). Atti Ist. Geol. Univ. Genova, 6, 273-889. - Lorenzoni, S. (1963). Metagrovacche, in facies epimetamorfica, a giadeite e gastaldite affioranti nel gruppo montuoso d’Ambin (Alpi Cozie). Ric. Sci. Ann., 33, ser. 2, part 2-A, 3(8), 1059-1066. - Lorenzoni, S. (1965). Studio geopetrografico del versante italiano del massico d’Ambin. Mem. Ist. Geol. Miner. Univ. Padova, 25, 1-88. - Lorenzoni, S. (1968). Etude pétrographique du versant italien du massif d’Ambin (Alpes franco-italiennes). Schweiz. mineral. petrogr. Mitt. , 48 (1), 428-436. - Lualdi, A. (1991). Il Trias superiore-Lias della Zona Sestri-Voltaggio (Unità di M. Gazzo-Isoverde). La sezione di Lencisa - M. dei Torbi. Atti Tic. Sci. Terra , 34, 121-132. - Lucchesi, S., Fioraso, G., Bertotto, S. & Chiarle, M. (2014). Little Ice Age and contemporary glacier extent in the Western and South-Western Piedmont Alps (North-Western Italy). J. Maps, 10 (3), 409-423. - Maffione, M., Speranza, F., Faccenna, C., Cascella, A., Vignaroli, G. & Sagnotti, L. (2008). A synchronous Alpine and Corsica-Sardinia rotation. J. Geophys. Res., 113(B3), B03104. - Malaroda, R. (1963). Les faciès à composante dé tritique dans le Cré tacé au- tochtone des Alpes-Maritimes italiennes. Geol. Rundsch., 53, 41-57. References 125

- Malaroda, R. (1998). Geomorfologia e neotettonica della Val Gallenca ed altre limitrofe nell’alto Canavese. It. J. Quatern. Sci., 11, 331-346. - Malaroda, R. (1999). Geological Map of Southern Argentera Massif (Maritime Alps). Explanatory Notes. Mem. Sci. Geol., 51, 241-331. - Malaroda, R., Carraro, F., Dal Piaz, G.V., Franceschetti, B., Sturani, C. & Zanella, E. (1970). Carta geologica del Massiccio dell’Argentera alla scala 1:50.000 e note illustrative. Mem. Soc. Geol. It., 9, 557-663. - Malusà, M.G., Mosca, P., Borghi, A., Dela Pierre, F. & Polino, R. (2002). Approccio multi-disciplinare per la ricostruzione dell’assetto tettono- stratigraﬁco e dell’evoluzione metamorﬁco-strutturale di un settore di catena orogenica: l’esempio dell’Alta Valle di Susa (Alpi occidentali). Mem. Soc. Geol. It., 57, 249-257. - Manatschal, G. & Müntener, O. (2009). A type sequence across an ancient magma-poor ocean-continent transition: The example of the western Alpine Tethys ophiolites. Tectonophysics , 473 (1-2), 4-19. - Mancktelow, N.S. (1985). The Simplon Line: A major displacement zone in the western Lepontine Alps. Eclogae geol. Helv., 78, 73-96. - Mancktelow, N.S. (1992). Neogene lateral extension during convergence in the Central Alps: Evidence from interrelated faulting and backfolding around the Simplon Pass (Switzerland). Tectonophysics , 215, 295-317. - Manzotti, P. & Ballèvre, M. (2013). Multistage garnet in high-pressure metasediments: Alpine overgrowths on Variscan detrital grains. Geology, 41(11), 1151-1154. - Manzotti, P., Le Carlier de Veslud, C., Le Bayon, B. & Ballèvre, M. (2014). Petro-structural map of the Money Unit (Gran Paradiso Massif, Valnontey valley, Western Alps) 1 to 5000. J. Maps, 10 (2), 324-340. - Marchesi, M., Mazzucchelli, M., Bottazzi, P., Ottolini, L. & Vannucci, R. (1992). Rocce subcrostali nella zona di Ivrea (Italia): i «corpi minori» della Val Strona. Atti Tic. Sci. Terra, 35, 97-106. - Marini, M. (1998). Carta geologica della Val Polcevera e zone limitrofe (Appennino Settentrionale) alla scala 1:25.000. Note illustrative. Atti Tic. Sci. Terra , 40, 33-64. - Marroni, M., Ottria, G. & Pandolfi, L. (2015). Note Illustrative della carta geologica d’Italia alla scala 1:50.000, Foglio 196 «Cabella Ligure». ISPRA, Serv. Geol. It., Roma. - Martin, S., Tartarotti, P. & Dal Piaz, G.V. (1994). The Mesozoic ophiolites of the Alps: A review. Boll. Geof. Teor. Appl ., 36 (141-144), 175-216. - Martinetto, E. (2001). Pliocene plants, environment and climate of northwestern Italy. Flora Tertiaria Mediterranea, 4, 1-88. 126 References

- Martinetto, E., Scardia, G. & Varrone, D. (2007). Magnetobiostratigraphy of the Stura di Lanzo fossil forest succession (Piedmont, Italy). Riv. It. Paleont. Strat., 113, 109-125. - Masini, E., Manatschal, G. & Mohn, G. (2013). The Alpine Tethys rifted margins: Reconciling old and new ideas to understand the stratigraphic architecture of magma-poor rifted margins. Sedimentology, 60, 174-196. - Matasci, B., Epard, J. L. & Masson, H. (2011). The Teggiolo zone: A key to the Helvetic-Penninic connection (stratigraphy and tectonics in the Val Bavona, Ticino, Central Alps). Swiss J. Geosci., 104, 257-284. - Maury, P. & Ricou, L.E. (1983). Le dé crochement subbrianç onnais: une nou- velle interpré tation de la limite interne-externe des Alpes franco-italiennes. Rev. Géol. Dyn. Gé ogr. Phys., 24 (1), 3-22. - Maxelon, M. & Mancktelow, N.S. (2005). Three-dimensional geometry and tectonostratigraphy of the Pennine zone, Central Alps, Switzerland and Northern Italy. Earth-Sci. Reviews, 71, 171-227. - Mazzucchelli, M., Marchesi, M., Bottazzi, P., Ottolini, L. & Vannucci, R. (1992). The Premosello Chiovenda peridotitic body in Ossola Valley (IVZ, Italy). Atti Tic. Sci. Terra, 35, 75-81. - Mazzucchelli, M., Quick, J.E., Sinigoi, S., Zanetti, A. & Giovanardi, T. (2014). Igneous evolutions across the Ivrea crustal section: The Permian Sesia Magmatic System and the Triassic Finero intrusion and mantle. GFT- Geological Field Trips, 6 (2.2), 1-98. Doi: 10.3301/GET2014. - Medeot, O., Callegari, E. & Cigolini, C. (1997). Petrochemical aspects of calc-alkalic and shoshonitic post-collisional Oligocene volcanics of the cover series of the Sesia-Lanzo Zone, Western Italian Alps. Abs. Vol., 3 rd Workshop Alpine Geol. St., (Oropa-Biella). Quad. Geod. Alp. Quatern., 4, 77-78. - Meggiolaro, V., Sapigni, M. & Fioretti, A.M. (2011). Tremolite-calcite veins in the footwall of the Simplon Fault, Antigorio Valley, Lepontine Alps (Italy). Swiss J. Geosci., 104 (3), 355-365. - Mehnert, K.R. (1975). The Ivrea Zone. A model of the deep crust. Neues Jahrbuch Mineral., Abh., 125, 156-199. - Merle, O., Cobbold, P.R. & Schmid, S. (1989). Tertiary kinematics in the Lepontine dome. Geol. Soc. London, Spec. Publ., 45, 113-134. - Messiga, B. & Scambelluri, M. (1991). Retrograde P-T-t path for the Voltri Massif eclogites (Ligurian Alps, Italy): Some tectonic implications. J. metam. Geol., 9, 93-109. - Messiga, B., Tribuzio, R. & Scambelluri, M. (1992). Mafic eclogites from the Valosio crystalline massif (Ligurian Alps, Italy). Schweiz. mineral. petrogr. Mitt., 72, 365-377. References 127

- Meulenkamp, J.E. & Sissingh, W. (2003). Tertiary palaeogeography and tectonostratigraphic evolution of the Northern and Southern Peri-Tethys platforms and the intermediate domains of the African-Eurasian convergent plate boundary zone. Palaeogeography, Palaeoclimatology, Palaeoecology , 196, 209-228. - Mével, C., Caby, R. & Kienast, J.R. (1978). Amphibolite facies conditions in the oceanic crust: Example of amphibolitized flaser-gabbro and amphibolites from the Chénaillet ophiolite massif (Hautes Alpes, France). Earth Planet. Sci. Letters, 39, 98-108. - Meyer, Ch., Marquer, D., Schmid, S.M. & Ciancaleoni, L. (1998). Syn- orogenic extension along the Forcola fault: Correlation of Alpine deformations in the Tambo and Adula nappes (Eastern Penninic Alps). Eclogae geol. Helv., 91, 409-420. - Michard, A. (1967). Etudes géologiques dans les zones internes des Alpes Cottiennes. Editions du CNRS, Paris, 447 p. - Michard, A., Avigad, D., Goffé, B. & Chopin, C. (2004). The high-pressure metamorphic front of the south Western Alps (Ubaye-Maira transect, France, Italy). Schweiz. mineral. petrogr. Mitt., 84, 215-235. - Michel, R. (1953). Les schistes cristallins des massifs du Grand Paradis et de Sesia-Lanzo (Alpes Franco-Italiennes). Sciences de la Terre , 1 (3/4), 1-287, with a 1:100,000 geological map. - Michetti, A.M., Giardina, F., Livio, F., Mueller, K., Serva, L., Sileo, G., Vittori, E., Devoti, R., Riguzzi, F., Carcano, C., Rogledi, S., Bonadeo, L., Brunamonte, F. & Fioraso, G. (2012). Active compressional tectonics, Quaternary capable faults, and the seismic landscape of the Po Plain (northorn Italy). Ann. Geoph., 55 (5). - Miletto, M. & Polino, R. (1992). A gravity model of the crust beneath the Tertiary Piemonte Basin (northwestern Italy). Tectonophysics , 212, 243-256. - Milnes, G., Greller, M. & Mü ller, R. (1981). Sequence and style of major post- nappe structures, Simplon-Pennine Alps: J. Struct. Geol., 3, 414-420. - Minnigh, L.D. (1977). A new klippe of «II Zona Diorito-Kinzigitica» in the Sesia Lanzo Zone. Rend. Soc. It. Min. Petr., 33 (1), 409-412. - Mohn, G., Manatschal, G., Müntener, O., Beltrando, M. & Masini, E. (2010). Unravelling the interaction between tectonic and sedimentary processes during lithospheric thinning in the Alpine Tethys margins. Int. J. Earth Sci., 99, 75-101. - Molli, G., Crispini, L., Malusà, M., Mosca, P., Piana, F. & Federico, L. (2010). Geology of the Western Alps-Northern Apennine junction area: A regional review. In: M. Beltrando, A. Peccerillo, M. Mattei, S. Conticelli & C. Doglioni 128 References

(Eds.). The Geology of Italy, J. Virtual Explorer, vol. 36, paper 10. Doi: 10.3809/jvirtex.2010.00215. - Moniè, P. (1990). Preservation of Hercynian 40 Ar/39 Ar ages through high- pressure low-temperature Alpine metamorphism in the western Alps. Eur. J. Mineral., 2, 343-361. - Morelli, M., Piana, F., Mallen, L., Nicolò, G. & Fioraso, G. (2011). Iso- Kinematic Maps from statistical analysis of PS-InSAR data of Piemonte, NW Italy: Comparison with geological kinematic trends. Remote Sens. Environ. , 115 (5), 1188-1201. - Mosca, P. (2006). Neogene basin evolution in the Western Po Plain (NW Italy). Insights from seismic interpretation, subsidence analysis and low temperature (U-Th)/He thermochronology. Ph.D. Thesis, Vrije Universiteit, Amsterdam , The Netherlands, 190 p. - Mosca, P., Polino, R., Rogledi, S., Rossi, M., Bertotti, G., Festa, A., Malusà, M. G. & Piana, F. (2005). Oligocene-Neogene kinematic constraints on the Alps and Apennine interaction in the western Po Plain from subsurface data. Rend. Soc. Geol. It., n.s., 1, 148-149. - Mosca, P., Borghi, A. & Gattiglio, M. (2008). Storia pre-alpina e alpina nel Massiccio di Ambin (Alpi Occidentali). Rend. Online Soc. Geol. It ., 1, 129-131. - Mosca, P., Polino, R., Rogledi, S. & Rossi, M. (2009). New data for the kinematic interpretation of the Alps-Apennines junction (Northwestern Italy). Int. J. Earth Sci., 99 (4), 833-849. - Musumeci, G. & Colombo, F. (2002). Late Variscan mylonitic granitoids in the Argentera Massif (Western Alps, Italy): age and kinematic constraints on the Ferriere-Mollières shear zone. C. R. Acad. Sci. Paris, 334, 213-220. - Mutti, E., Papani, L., Di Biase, D., Davoli, G., Mora, S., Segadelli, S. & Tinterri, R. (1995). Il Bacino Terziario Epimesoalpino e le sue implicazioni sui rapporti tra Alpi ed Appennino. Mem. Soc. Geol. It., 47, 217-244. - Muttoni, G., Gaetani, M., Kent, D.V., Sciunnach, D., Angiolini, L., Berra, F. et al. (2009). Opening of the Neo-Tethys Ocean and the Pangea B to Pangea A transformation during the Permian. GeoArabia, 14 (4), 17-48. - Nicolas, A. (1966). Étude pétrochimique des roches vertes et de leurs minéraux entre Dora Maïra et Grand Paradis (Alpes Piémontaises): Tectonique et méta- morphisme. Tome I (1-178); Le complexe Ophiolites-Schistes lustrés entre Dora Maïra et Grand Paradis (Alpes Piémontaises): Tectonique et métamorphi- sme. Tome II (179-299). Thèse Universitaire, Université de Nantes. - Nicolas, A. (1967). Géologie des Alpes piémontaises entre Dora Maira et Grand Paradis. Trav. Lab. Géol. Fac. Sci. Grenoble , 43, 139-167. - Nicolas, A., Hirn, A., Nicolich, R., Polino, R. & Group, E.C.W. (1990). References 129

Lithospheric wedging in the Western Alps inferred from the ECORS-CROP traverse. Geology, 18, 587-590. - Niggli et al. (1973). Metamorphic Map of the Alps 1:1.000,000. Subcommission Cartography Metam. Belts of the World & UNESCO. - North American Commission on Stratigraphic Nomenclature (2005). North American Stratigraphic Code, Am. Ass. Petrol. Geol. Bull., 89, 11, 1547-1591. - Novarese, V. (1929). La Zona del Canavese e le formazioni adiacenti. Mem. descr. Carta Geol. It., 22, 65-212. - Novarese, V. (1931). La formazione diorito-kinzigitica in Italia. Boll. R. Uff. Geol., 56 (7), 1-62. - Novaretti, A., Bicchi, E., Condello, A., Ferrero, E., Maia, F., Tonon, M. & Torta, D. (1995). La successione oligo-miocenica del Monferrato: sintesi dei dati biostratigrafici. In: R. Polino & R. Sacchi (Eds.). Atti Conv. Rapporti Alpi-Appennino. Acc. Naz. Sci., Scritti e Doc., 14, 39-60. - Oberhänsli, R. (2004). Metamorphic structure of the Alps. Explanatory Notes to the Map. Mitt. Österreich. Miner. Ges., 149, 115-226. - Oberhänsli, R., Hunziker, J.C., Martinotti, G. & Stern, W.B. (1985). Geo- chemistry, geochronology and petrology of Monte Mucrone: An example of eo-Alpine eclogitisation of Permian granitoids in the Sesia Lanzo zone, western Alps, Italy. Chem. Geol. (Isotope Geosci. Section), 52, 165-184. - Ogniben, L., Parotto, M. & Praturlon, A. (Eds.) (1975). Structural model of Italy (1:1.000.000). Maps and Explanatory Notes. Quaderni de «La Ricerca Scientifica». C.N.R., Roma, 90, 502 p. - Ogniben, L. et al. (1990). Gravimetric map of Italy 1:500.000, attached to: Bigi et al ., (1990) Structural Model of Italy, C.N.R., Progetto Finalizzato Geodinamica, Litografia SELCA, Firenze. - Pagliani Peyronel, G. (1959). Il granito porfirico della media Valle del Cervo (Biella). Rend. Ist. Lombardo Sci. e Lett., 93, 379-398. - Papani, G. & Zanzucchi, G. (1969). Nuove unità litostratigrafiche dell’Appen- nino emiliano: il Flysch di Monte Cassio. Ateneo Parmense, Acta Naturalia, 5 (1), 1-16. - Paquette, J.-L., Chopin, Ch. & Peucat, J.-J. (1989). U-Pb zircon, Rb-Sr and Sm-Nd geochronology of high- to very-high-pressure meta-acidic rocks from the western Alps. Contr. Mineral. Petrol., 101 (3), 280-289. - Pasquarè, G., Abbate, E., Castiglioni G.B., Merenda, L., Mutti, E., Ortolani, F., Parotto, M., Pignone, R., Polino, R., Premoli Silva, I. & Sassi, F.P. (1992). Guida al rilevamento e all’informatizzazione della Carta Geologica d’Italia alla scala 1:50.000. Quaderni Servizio Geol. Naz., Serie III, 1, 1-203. 130 References

- Pavia, G., Chiambretto, L. & Oreggia, G. (1989). Paleocomunità a molluschi nel Pliocene inferiore di Breolungi (Mondovì, Italia NW). Atti 3° Simp. Ecol. Paleoecol. Comun. Bent. (1985), 521-569. - Pawlig, S. (2001). Geological Evolution of the Monte Rosa: Constraints from geochronology and geochemistry of a Talc-Kyanite-Chloritoid shear zone within the Monte Rosa Granite (Monte Rosa Nappe, Italian Western Alps). PhD Thesis, Mainz Univ., 149 p. - Pawlig, S. & Baumgartner, L. (2001). Geochemistry of a talc-kyanite-chloritoid shear zone within the Monte Rosa granite, Val d’Ayas, Italy. Schweiz. mineral. petrogr. Mitt., 81, 329-346. - Perrone, G., Morelli, M., Piana, F., Fioraso, G., Nicolò, G., Mallen, G., Cadoppi, P., Balestro, G. & Tallone, S. (2013). Current tectonic activity and differential uplift along the Cottian Alps/Po Plain boundary (NW Italy) as derived by PS-InSAR data. J. Geodynamics, 66, 65-78. - Petrucci, F., Bortolami, G.C. & Dal Piaz, G.V. (1970). Carta geo-morfologica dell’Anfiteatro morenico di Rivoli-Avigliana (Prov. Torino) e del suo substrato cristallino. In: G.C. Bortolami & G.V. Dal Piaz. Il substrato cristallino dell’An- fiteatro morenico di Rivoli-Avigliana (Prov. Torino) e alcune considerazioni sull’evoluzione paleografica e strutturale della eugeosinclinale piemontese. Mem. Soc. It. Sc. nat., Mus. Civico Storia nat. Milano, 18 (3), 125-169, 1 carta 1:40.000. - Pfeifer, H.R., Colombi, A. & Ganguin, J. (1989). Zermatt-Saas and Antrona zone: A petrographic and geochemical comparison of polyphase metamorphic ophiolites of the western-central Alps. Schweiz. mineral. petrogr. Mitt ., 69, 217-236. - Pfiffner, O.A., Lehner, P., Heitzmann, P., Mueller, S. & Steck, A. (1997). Deep structure of the Alps: Results from NRP 20. Birkhäuser Verlag, Basel. - Piana, F. (2000). Structural setting of Western Monferrato (Alps-Apennines Junction Zone, NW Italy). Tectonics , 19, 943-960. - Piana, F. & Polino, R. (1995). Tertiary structural relationships between Alps and Apennines: The critical Torino Hill and Monferrato area, Northwestern Italy. Terra Nova , 7, 138-143. - Piana, F., d’Atri, A. & Orione, P. (1997). The Visone formation: A marker for the Early Miocene tectonics in the Alto Monferrato domain (Tertiary Piemonte Basin, NW, Italy). Mem. Sci. Geol., 49, 145-162. - Piana, F., Tallone, S., Cavagna, S. & Conti, A. (2006). Thrusting and faulting in metamorphic and sedimentary units of Ligurian Alps: An example of integrated field work and geochemical analyses. Int. J. Earth Sci., 95, 413-430. - Piana, F., Musso, A., Bertok, C., d’Atri, A., Martire, L., Perotti, E., Varrone, References 131

D. & Martinotti, G. (2009). New data on post-Eocene tectonic evolution of the External Ligurian Brianconnais (Western Ligurian Alps). Boll. Soc. Geol. It ., 128, 353-366. - Piana, F., Battaglia, S., Bertok, C., d’Atri, A., Ellero, E., Leoni, L., Martire, L. & Perotti, E. (2014). Illite (KI) and chlorite (AI) «crystallinity» indices as a constraint for the evolution of the External Brianç onnais Front in Western Ligurian Alps (NW Italy). It. J. Geosci., 133 (3), 445-454. - Piana, F., Lombardo, V., Mimmo, D., et al. (2017a). The Geodatabase of the Piemonte Geological Map: Conceptual design for knowledge encoding. Rend. Online Soc. Geol. It., 42, 85-89. - Piana, F., Fioraso, G., Irace, A., Mosca, P., d’Atri, A., Barale, L., Falletti, P. Monegato, G., Morelli, M., Tallone, S. & Vigna, G.B. (2017b). Geology of Piemonte region (NW Italy, Alps–Apennines interference zone), Journal of Maps, 13:2, 395-405. Doi: 10.1080/17445647.2017.1316218. - Piccardo, G.B. (1984). Le ofioliti del gruppo di Voltri, Alpi Liguri: caratteri primari ed interpretazione geodinamica. Mem. Soc. Geol. It., 28, 95-114. - Piccardo, G.B. (2010). The Lanzo peridotite massif, Italian Western Alps: Jurassic rifting of the Ligurian Tethys. Geol. Soc. London, Spec. Publ ., 337, 47-69. - Picotti, V. & Pazzaglia, F.J. (2008). A new active tectonic model for the construction of the Northern Apennines mountain front near Bologna (Italy). J. Geophys. Res., 113, B08412. Doi: 10.1029/2007JB005307. - Pieri, M. & Groppi, G. (1981). Subsurface Geological Structure of the Po Plain, Italy. Prog. Fin. Geodin ., Agip-CNR, pubbl. 414. - Pleuger, J., Nagel T.J., Walter, J., Jansen, E. & Froitzheim, N. (2008). On the role and importance of orogen-parallel and -perpendicular extension, transcur- rent shearing, and backthrusting in the Monte Rosa nappe and the Southern Steep Belt of the Alps (Penninic zone, Switzerland and Italy). Geol. Soc. London, Spec. Publ., 298, 251-280. - Pognante, U. (1979a). Studio geologico-petrografico del Complesso dei «Micascisti Eclogitici» lungo la valle d’Aosta tra Quincinetto, Ivozio e la Colma di Mombarone, con carta geologica alla scala 1:10.000, M. Sc. Thesis, Univ. of Torino, 125 p. (unpubl.). - Pognante, U. (1979b). The Orsiera-Rocciavré meta-ophiolitic complex (Italian Western Alps). Ofioliti, 4, 189-198. - Pognante, U. (1980). Preliminary data on the Piemonte ophiolite nappe in lower Val Susa-Val Chisone area, Italian Western Alps. Ofioliti, 5, 221-240. - Pognante U. (1983). Les intercalations gneissiques dans une unité des «schistes lustrés» de la vallée de Suse (Alpes occidentales): témoins d’une marge continentale subductée? C. R. Acad. Sci. Paris, 296, 379-382. 132 References

- Pognante, U. (1989). Lawsonite, blueschist and eclogite formation in the southern Sesia Zone (western Alps, Italy). Eur. J. Mineral., 1, 89-104. - Pognante, U., Talarico, F., Rastelli, N. & Ferrati, N. (1987). High pressure metamorphism in the nappes of the valle dell’Orco traverse (western Alps collisional belt). J. metam. Geol., 5, 397-414. - Polino, R. (1984). Les séries océaniques du haut Val de Suse (Alpes Cottiennes): analyse des couvertures sédimentaires. Ofioliti, 9, 547-554. - Polino, R. & Dal Piaz, G.V. (1978). Geologia dell’alta Val d’Isère e del bacino del Lago Serrù (Alpi Graie). Mem. Ist. Geol. Min. Univ. Padova, 32, 1-20. - Polino, R., Monticelli, F. & Vaccaro, D. (1983). L’unità piemontese Chaberton- Grand Hoche (Val Susa-Alpi Occidentali): evoluzione litostratigrafica, assetto strutturale e rapporti con i complessi circostanti. Mem. Soc. Geol. It ., 26, 489-498. - Polino, R. & Lemoine, M. (1984). Détritisme mixte d’origine continentale et océanique dans les sédiments jurassico-crétacés supra-ophiolitiques de la Téthys ligure: la série du Lago Nero (Alpes occidentales franco-italiennes). C.R. Acad. Sci. Paris, 298, 359-364. - Polino, R., Dal Piaz, G.V. & Gosso, G. (1990). Tectonic erosion at the Adria margin and accretionary process for the Cretaceous orogeny in the Alps. In: F. Roure, P. Heitzmann & R. Polino (Eds.). Deep Structure of the Alps. Mem. Soc. Geol. Fr ., 156; Mem. Soc. Geol. Suisse , 1; Vol. Spec. Soc. Geol. It ., 1, 345-367. - Polino, R., Borghi, A., Carraro, F., Dela Pierre, F., Fioraso, G. & Giardino, M. (2002). Note illustrative della Carta Geologica d’Italia alla scala 1:50.000. Foglio 132-152-153 «Bardonecchia». Servizio Geologico d’Italia, 128 p. Litografia GEDA, Nichelino (Torino). - Principi, G., Bortolotti, V., Chiari, M., Cortesogno, L., Gaggero, L., Marcucci, M., Saccani, M. & Treves, B. (2004). The Pre-Orogenic Volcano-Sedimentary Covers of the Western Tethys Oceanic Basin: A review. Ofioliti, 29 (2), 177-211. - Quick, J.E., Sinigoi, S. & Mayer, A. (1995). Emplacement of mantle peridotite in the lower continental crust, Ivrea-Verbano zone, Northwest Italy. Geology, 23, 739-742. - Quick, J.E., Sinigoi, S., Snoke, A.W., Kalakay, T.J., Mayer, A. & Peressini, G. (2003). Geologic map of the southern Ivrea-Verbano zone, Northwestern Italy. Geologic Investigations Series, Map I-2776, U.S. Geol. Survey, U.S. Gov. Printing Office. - Quick, J.E., Sinigoi, S., Peressini, G., Demarchi, G., Wooden, J.L. & Sbisa, A. (2009). Magmatic plumbing of a large Permian caldera exposed to a depth of 25 km. Geology, 37, 603-606. References 133

- Rasetti G.E. (1897). Il Monte Fenera di Valsesia. Studio Geopaleontologico. Boll. Soc. Geol. It., 16, 141-175. - Rebay, G. & Spalla, M.I. (2001). Emplacement at granulite facies conditions of the Sesia–Lanzo metagabbros: An early record of Permian rifting? Lithos, 58 (3), 85-104. - Regis, D., Rubatto, D., Darling, J., Cenki-Tok, B., Zucali, M. & Engi, M. (2014). Multiple metamorphic stages within an eclogite-facies Terrane (Sesia Zone, Western Alps) revealed by Th–U–Pb petrochronology. J. Petrol ., 55 (7), 1429-1456. - Ricci Lucchi, F. (1986). Oligocene to Recent foreland basins of Northern Apennines. Intern. Assoc. Sedim., Spec. Publ. No. 8, 105-139. Blackwell. - Ricou, L.E. (1981). Glissement senestre des nappes penniques le long de la bordure nord de l’Argentera: son rôle dans le jeu de l’arc alpin. C.R. Acad. Sci. Paris, 292 (II7), 1305-1308. - Ricou, L.E. & Siddans, A.W.B. (1986). Collision tectonics in the Western Alps. In: M.P. Coward & A.C. Ries (Eds.). Collision tectonics. Geol. Soc. London, Spec. Publ., 19, 229-244. - Ridley J.R. (1989). Structural and metamorphic history of a segment of the Sesia-Lanzo Zone, and its bearing on the kinematics of Alpine deformation in the Western Alps. In: M.P. Coward et al. (Eds.). Alpine Tectonics. Geol. Soc. London, Spec. Publ., 45, 189-201. - Ring, U., Collins, A.S. & Kassem, O.K. (2005). U–Pb SHRIMP data on the crystallization age of the Gran Paradiso augengneiss, Italian Western Alps: Further evidence for Permian magmatic activity in the Alps during break-up of Pangea. Eclogae geol. Helv., 98, 363-370. - Rivalenti, G., Garuti, G. & Rossi, A. (1975). The origin of the Ivrea-Verbano basic formation (western Italian Alps): Whole rock geochemistry. Boll. Soc. Geol. It., 94, 1149-1186. - Rivalenti, G., Garuti, G., Rossi, A. Siena, F. & Sinigoi, S. (1981). Existence of different peridotite types and of a layered igneous complex in the Ivrea zone of the western Alps. J. Petrol ., 22, 127-153. - Rivalenti, G., Rossi, A., Siena, F. & Sinigoi, S. (1984). The layered series of the Ivrea-Verbano Igneous Complex, Western Alps, Italy. Tschermaks Min. Petr. Mitt., 33, 77-99. - Rivalenti, G. & Mazzucchelli, M. (2000). Interaction of mantle derived magmas and crust in the IVZ and the Ivrea mantle peridotites. In: G. Ranalli, C.A. Ricci & V. Trommsdorff (Eds.). Crust-Mantle Interactions. Proc. Int. School Earth Planet. Sci., 153-198. 134 References

- Rodgers, J. & Bearth, P. (1960). Zum Problem der Lebendundecke. Eclogae geol. Helv. 53(1), 169-178. - Romer, R., Scharer, U. & Steck, A. (1996). Alpine and pre-Alpine magmatism in the root zone of the Western Alps. Contrib. Mineral. Petrol ., 123, 138-158. - Rook, L. & Martínez-Navarro, B. (2010). Villafranchian: The long story of a Plio-Pleistocene European large mammal biochronologic unit. Quaternary Intern., 219, 134-144. - Rosenbaum, G., Lister, G.S. & Duboz, C. (2002). Relative motions of Africa, Iberia and Europe during Alpine orogeny. Tectonophysics , 359, 117-129. - Rosenberg, C.L. (2004). Shear zones and magma ascent: A model based on a review of the Tertiary magmatism in the Alps. Tectonics , 2, 1-21. - Rossetti, P., Agangi, A., Castelli, D., Padoan, M. & Ruffini, R. (2007). The Oligocene Biella pluton (western Alps, Italy): New insights on the magmatic vs. hydrothermal activity in the Valsessera roof zone. Per. Mineral ., 76 (2-3), 223-240. - Rossi, M., Mosca, P., Polino, R., Rogledi, S. & Biffi, U. (2009). New outcrop and subsurface data in the Tertiary Piedmont Basin (NW-Italy): Unconformi- ty-bounded stratigraphic units and their relationships with basin-modification phases. Riv. It. Paleont. Stratigr., 115 (3), 305-335. - Roure, F., Polino, R. & Nicolich, R. (1990). Early Neogene deformation beneath the Po Plain: Constraints of the post-collisional Alpine evolution. In: F. Roure, P. Heitzmann & R. Polino (Eds.). Deep Structure of the Alps. Mem. Soc. Geol. Fr ., 156; Mem. Soc. Geol. Suisse, 1; Vol. Spec. Soc. Geol. It ., 1, 309-322. - Roure, F., Bergerat, F., Damotte, B., Mugnier, J.-L. & Polino, R. (1996). The ECORS-CROP Alpine seismic traverse. Mém. Soc. Géol. Fr., 170, 113 p. - Roveri, M., Bassetti, M.A. & Ricci Lucchi, F. (2001). The Mediterranean Messinian salinity crisis: An Apennine foredeep perspective. Sediment. Geol., 140, 201-214. - Roveri, M., Manzi, V., Ricci Lucchi, F. & Rogledi, S. (2003). Sedimentary and tectonic evolution of the Vena del Gesso basin (Northern Apennines, Italy): Implications for the onset of the Messinian salinity crisis. Geol. Soc. Am. Bull., 115, 387-405. - Roveri, M., Lugli, S., Manzi, V. & Schreiber B.C. (2008). The Messinian salinity crisis: A sequence stratigraphic approach. GeoActa, Spec. Publ., 1, 117-138. - Rowan, M.G. (1990). The Upper Cretaceous Helminthoides Flysch of the Northern Apennines and Maritime Alps: Correlation and provenance. Ofioliti, 15, 305-326. References 135

- Rubatto, D., Gebauer, D. & Fanning, M. (1998). Jurassic formation and Eocene subduction of the Zermatt-Saas-Fee ophiolites: Implications for the geodynamic evolution of the Central and Western Alps. Contrib. Mineral. Petrol ., 132, 269-287. - Rubatto, D., Gebauer, D. & Compagnoni, R. (1999). Dating of eclogite-facies zircons: The age of Alpine metamorphism in the Sesia-Lanzo Zone (Western Alps). Earth Planet. Sci. Lett., 167, 141-158. - Rubatto, D., Schaltegger, U., Lombardo, B., Colombo, F. & Compagnoni, R. (2001). Complex Paleozoic magmatic and metamorphic evolution in the Argentera Massif (Western Alps) resolved with U-Pb dating. Schweiz. mineral. petrogr. Mitt., 81, 213-228. - Rubatto, D., Ferrando, S., Compagnoni, R. & Lombardo, B. (2010). Carboniferous high pressure metamorphism of Ordovician protoliths in the Argentera Massif (Italy), Southern European Variscan belt. Lithos, 116, 65-76. - Rutter, E.H., Brodie, K.H. & Evans, P. (1993). Structural geometry, lower crustal magmatic underplating and lithospheric stretching in the Ivrea-Verbano zone, N. Italy. J. Struct. Geol., 15, 647-662. - Rutter, E.H., Khazanehdari, J., Brodie, K.H., Blundell, D. & Waltham, D. (1999). Synthetic seismic reflection profile through the Ivrea-Verbano zone - Serie dei Laghi continental crustal section, northwestern Italy. Geology, 27, 79-82. - Sacchi, R. (1977). Gli Scisti di Rimella tra Sesia e Toce: una re-interpretazione. Mem. Ist. Geol. Miner. Univ. Padova, 32, 3-20. - Salvador, A. (Ed.) (1994). International Stratigraphic Guide: A Guide to Stratigraphic Classification, Terminology, and Procedure. Second Edition. Intern. Union of Geol. Sci. & Geol. Soc. America. - Sandrone, R., Cadoppi, P., Sacchi, R. & Vialon, P. (1993). The Dora-Maira Massif. In: J.F. von Raumer & F. Neubauer (Eds.). Pre-Mesozoic Geology in the Alps. Springer-Verlag, Berlin , 317-325. - Sartori, M., Gouffon, Y. & Marthaler, M. (2006). Harmonisation et définition des unités lithostratigraphiques briançonnaises dans les nappes penniques du Valais. Eclogae geol. Helv., 99, 363-407. - Scambelluri, M., Hoogerduijn Strating, E.H., Piccardo, G.B., Vissers, R.L.M. & Rampone, E. (1991). Alpine olivine and titanian clinohumite-bearing assemblages in the Erro-Tobbio peridotite (Voltri Massif, NW Italy). J. metam. Geol., 9, 79-91. - Scardia, G., Festa, A., Monegato, G., Pini, R., Rogledi, S., Tremolada, F. & Galadini, F. (2015). Evidence for late Alpine tectonics in the Lake Garda area (Northern Italy) and seismogenic implications. Geol. Soc. Am. Bull ., 127, 113-130. 136 References

- Scheiber, T., Pfiffner, O. A. & Schreurs, G. (2013). Upper crustal deformation in continent-continent collision: A case study from the Bernard nappe complex (Valais, Switzerland), Tectonics , 32, 1320-1342. - Schettino, A. & Turco, E. (2009). Breakup of Pangaea and plate kinematics of the central Atlantic and Atlas regions. Geophys. J. Intern., 178 (2), 1078-1097. - Scheuring, B., Ahrendt, H., Hunziker, J.C. & Zingg, A. (1974). Palaeobotanical and geochronological evidence for the Alpine age of the metamorphism in the Sesia-Zone. Geol. Rundsch., 63 (1), 305-326. - Schmid, R. (1968). Excursion guide for the Valle d’Ossola section of the Ivrea- Verbano Zone. Schweiz. mineral. petrogr. Mitt., 48 (1), 305-314. - Schmid, R. (1978/1979). Are the metapelites of the Ivrea-Verbano Zone resti- tes? Mem. Ist. Geol. Mineral. Univ. Padova, 33, 67-69. - Schmid, S.M. (1993). Ivrea Zone and Adjacent Southern Alpine Basement. In: J.F. von Raumer & F. Neubauer (Eds.). Pre-Mesozoic Geology in the Alps , Springer Verlag, Berlin, 567-583. - Schmid, S.M., Zingg, A. & Handy, M. (1987). The kinematics of movements along the Insubric Line and the emplacement of the Ivrea Zone. Tectonophysics , 135, 47-66. - Schmid, S.M., Aebli, H.R., Heller, F. & Zingg, A. (1989). The role of the Periadriatic line in the tectonic evolution of the Alps. In: M.P. Coward, D. Dietrich & R.G. Park (Eds.). Alpine Tectonics. Geol. Soc. London, Spec. Publ., 45, 153-171. - Schmid, S.M., Pfiffner, A.O., Froitzheim, N., Schönborn, G. & Kissling, E. (1996). Geophysical-geological transect and tectonic evolution of the Swiss- Italian Alps. Tectonics , 15, 1036-1064. - Schmid, S.M., Fügenshuh, B., Kissling E. & Schuster, R. (2004). Tectonic map and overall architecture of the Alpine orogen. Eclogae geol. Helv., 97, 93-117. - Schmid, S.M., Kissling, E., Diehl, T. et al. (2017). Ivrea mantle wedge, arc of the Western Alps, and kinematic evolution of the Alps–Apennines orogenic system. Swiss J. Geosci., 110, 581-612, 1-32. - Schumacher, M.E. & Laubscher, H.P. (1996). 3D crustal architecture of the Alps-Apennines join - a new view on seismic data. Tectonophysics , 260, 349-361. - Seno, S., Dallagiovanna, G. & Vanossi, M. (2005). A kinematic evolution model for the Penninic sector of the central Ligurian Alps. Int. J. Earth Sci ., 94, 114-129. - Seton, M., Muller, R.D., Zahirovic, S., Gaina, C., Torsvik, T., Shephard, G.E., Talsma, A.S., Gurnis, M., Turner, M., Maus, S. & Chandler, M.T. (2012). References 137

Global continental and ocean basin reconstructions since 200 Ma. Earth-Sci. Reviews, 113, 212-270. - Siena, F. & Coltorti, M. (1989). The petrogenesis of a hydrated mafic - ultramafic complex and the role of amphibole fractionation at Finero (Italian Western Alps). Neues Jahrb. Miner., Monatsh., 6, 255-274. - Sills, J.D. & Tarney, J. (1984). Petrogenesis and tectonic significance of amphibolites interlayered with metasedimentary gneisses in the Ivrea Zone, Southern Alps, northwest Italy. Tectonophysics , 107, 187-206. - Sinclair, H.D. (1997). Tectono–stratigraphic model for under-filled peripheral foreland basins: An Alpine perspective. Geol. Soc. Am. Bull., 109, 324-346. - Sinigoi, S., Quick, J.E. & Demarchi, G. (2010). The Sesia magmatic system. In: Beltrando, M., Peccerillo, A., Mattei, M., Conticelli, S. & Doglioni C. (Eds.), The Geology of Italy. J. Virtual Explorer ., 36 (paper 4). Doi: 10.3809/ jvirtex.2009.00218. - Smith, A.G. (1976). Plate tectonics and orogeny: A review. Tectonophysics , 33, 215-285. - Spalla, M.I. & Zulbati, F. (2003). Structural and petrographic map of the southern Sesia-Lanzo zone (Monte Soglio-Rocca Canavese, western Alps, Italy). Mem. Sci. Geol. (Padova) , 55, 119-127. - Spring, L., Reymond, B., Masson, H. & Steck, A. (1992). La nappe du Lebendun entre Alte Kaserne et le Val Cairasca (Massif du Simplon): nouvelles observations et interprétations. Eclogae geol. Helv., 85 (1), 85-104. - Stampfli, G.M. (2000). Tethyan oceans. In: E. Bozkurt, J.A. Winchester & J.D.A. Piper (Eds.). Tectonics and Magmatism in Turkey and Surrounding Area. Geol. Soc. London, Spec. Publ., 173, 163-185. - Stampfli, G.M. & Borel, G.D. (2002). A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored synthetic oceanic isochrons. Earth Planet. Sci. Lett., 196 (1-2), 17-33. - Stampfli, G., Borel, G., Marchant, R. & Mosar, J. (2002). Western Alps geological constraints on western Tethyan reconstructions. J. Virtual Explorer , 8, 77-106. - Steck, A. (2008). Tectonics of the Simplon massif and Lepontine gneiss dome: Deformation structures due to collision between the underthrusting European plate and the Adriatic indenter. Swiss J. Geosci., 101, 515-546. - Steck, A., Ramsay, J.G., Milnes, A.G. & Burri, M. (1979). Compte rendu de l’excursion de la Socié té Géologique Suisse et de la Société Suisse de Minéralogie et Pétrographie en Valais et en Italie du nord du 2 au 5 octobre 1978. Eclogae geol. Helv., 72 (1), 287-311. 138 References

- Steck, A., Epard, J.-L., Escher, A., Lehner, P., Marchant, R. & Masson, H. (1997). Geological interpretation of the seismic profiles through Western Switzerland: Rawil (W1), Val d’Anniviers (W2), Mattertal (W3), Zmutt- Zermatt-Findelen (W4) and Val de Bagnes (W5). In: O.A. Pfiffner, P. Lehner, P. Heitzmann, S. Mueller & A. Steck (Eds.). Deep structure of Swiss Alps: Results of NRP 20 (241-250). Basel: Birkhäuser. - Steck, A., Bigioggero, B., Dal Piaz, G.V., Escher, A., Marchant, R., Martinotti, G. & Payot, S. (1999). Carte tectonique des Alpes de Suisse occidentale (1:100.000). Feuille 47 Monte Rosa. Service hydrol. national, Suisse. - Steck, A., Epard, J.L., Escher, A., Gouffon, Y. & Masson, H. (2001). Notice explicative de la carte géologique des Alpes de Suisse occidentale 1:100.000. Carte géologique spéciale N° 123. Berne: Office fédé ral des Eaux et de la Géologie, Suisse. - Steck, A., Della Torre, F., Keller, F., Pfeifer, H.R., Hunziker, J. & Masson, H. (2013). Tectonics of the Lepontine Alps: Ductile thrusting and folding in the deepest tectonic levels of the Central Alps. Swiss J. Geosci., 106 (3), 427-450. - Steck, A., Masson, H. & Robyr, M. (2016). Tectonics of the Monte Rosa and surrounding nappes (Switzerland and Italy): Tertiary phases of subduction, thrusting and folding in the Pennine Alps. Swiss J. Geosci., 108, 3-34. - Steininger F.F., Aubry M.P., Berggren W.A. et al. (1997). The Global Stratotype Section and Point (GSSP) for the base of the Neogene. Episodes, 20, 23-28. - Stille, P. & Bulletti, M. (1987). Nd-Sr isotopic characteristics of the Lugano volcanic rocks and constraints on the continental crust formation in the South Alpine domain (N Italy-Switzerland). Contrib. Mineral. Petrol ., 96, 140-150. - Stille, P. & Oberhänsli, R. (1987). Petrology and Alpine metamorphic evolution of the metabasic and ultrabasic rocks in the Berisal crystalline complex (Switzerland). Lithos, 20, 169-180. - Sturani, C. (1962). Il complesso sedimentario autoctono all’estremo nord-occidentale del Massiccio dell’Argentera (Alpi Marittime). Mem. Ist. Geol. Min. Univ. Padova, 22, 1-206. - Sturani, C. (1963). La couverture sédimentaire de l’Argentera–Mercantour dans le secteur compris entre les Barricate et Vinadio (haute vallée de la Stura di Demonte, Italie). Trav. Lab. Gé ol. Grenoble , 39, 83-124. - Sturani, C. (1973). Considerazioni sui rapporti tra Appennino settentrionale ed Alpi occidentali. Mem. Accad. Naz. Lincei, 183, 119-142. - Sturani, C. (1975). Explanatory notes on the western Alps (from the Sestri- Voltaggio line to the Val d’Ossola. In: L. Ogniben, M. Parotto & A. Praturlon (Eds.). Structural Model of Italy. Quaderni de «La Ricerca Scientifica». C.N.R., Roma, 149-174. References 139

- Sturani, C. (1976). Messinian facies in the Piedmont basin. Mem. Soc. Geol. It ., 16, 11-25. - Sturani, C. & Kerckhove, C. (1963). Sur la termination sud orientale de la nappe du Flysch à Helminthoï des à proximité du massif de l’Argentera (versant italien du col de Larche ou de la Maddalena). Trav. Lab. Gé ol. Grenoble , 39, 213-229. - Sturani, C. & Sampò, M. (1973). Il Messiniano inferiore in facies diatomitica nel Bacino Terziario Piemontese. Mem. Soc. Geol. It., 12, 335-338. - Tartarotti, P., Zucali, M., Panseri, M., Lissandrelli, S., Capelli, S. & Bachir, O. (2011). Mantle origin of the Antrona serpentinites (Antrona ophiolites, Pennine Alps) as inferred from microstructural, microchemical, and neutron diffraction quantitative texture analysis. Ofioliti, 36 (2), 167-189. - Trenkwalder, S., Violanti, D., d’Atri, A., Lozar, F., Dela Pierre, F. & Irace, A. (2008). The Miocene/Pliocene boundary and the Early Pliocene micropalae- ontological record: New data from the Tertiary Piedmont Basin (Moncucco quarry, Torino Hill, Northwestern Italy). Boll. Soc. Paleont. It ., 47 (2), 87-103. - Tricart, P. (1984). From passive margin to continental collision: A tectonic scenario for the Western Alps. Am. J. Sci., 284, 97-120. - Trommsdorff, V. (1990). Metamorphism and tectonics of the Central Alps: The Alpine lithospheric melange of Cima Lunga and Adula. Mem. Soc. Geol. It ., 45, 39-49. - Tropeano, D. & Olive, P. (1993). Eventi geomorfologici nelle Alpi italiane e nella Pianura occidentale del Po: inquadramento cronologico in base a radio- datazione 14 C. Il Quaternario, 6 (2), 189-204. - Trümpy, R. (1955). Remarques sur la corrélation des unités penniques externes entre la Savoie et le Valais et sur l’origine des nappes préalpines. Bull. Soc. géol. France, 6 (5), 217-223. - Trümpy, R. (2001). Why plate tectonics was not invented in the Alps. Int. J. Earth Sci., 90, 477-483. - Turco, F. & Tartarotti, P. (2006). The Antrona nappe: Lithostratigraphy and metamorphic evolution of ophiolites in the Antrona Valley (Pennine Alps). Ofioliti, Spec. Issue «Modern and fossil oceanic lithosphere» , 31, 207-221. - Vander Auwera, J. & Andre, L. (1990). Trace elements (REE) and isotopes (O, C, Sr) to characterize the metasomatic fluid sources: Evidence from the skarn deposit (Fe, W, Cu) of Traversella (Ivrea, Italy). Contrib. Mineral. Petrol ., 106, 325-339. - van Marke de Lummen, G. & Vander Auwera, J. (1990). Petrogenesis of the Traversella diorite (Piemonte Italy): A major trace element and isotopic (O, Sr) model. Lithos, 24, 121-136. 140 References

- Vanossi, M. (1970). Contributi alla conoscenza delle unità stratigrafico-strutturali del Brianzonese ligure s.l. IV - Messa a punto generale. Atti Ist. Geol. Univ. Pavia, 21, 109-114. - Vanossi, M. (1972). Rilevamento geologico ed analisi strutturale delle dorsali del M. Mongioie e del M. Cimone (Brianzonese ligure). Atti Ist. Geol. Univ. Pavia, 23, 29-71. - Vanossi, M., Cortesogno, L., Galbiati, B., Messiga, B., Piccardo, G. & Vannucci, R. (1984). Geologia delle Alpi Liguri: dati, problemi, ipotesi. Mem. Soc. Geol. It., 28, 5-75. - Vanossi, M., Perotti, C.R. & Seno, S. (1994). The Maritime Alps arc in the Ligurian and Tyrrhenian system. Tectonophysics , 230, 75-89. - Varrone, D. & Clari, P.A. (2003). Evolution stratigraphique et paléo-environ- nementale de la Formation à Microcodium et des Calcaires à Nummulites dans les Alpes Maritimes franco-italiennes. Geobios, 36, 775-786. - Vearncombe, J.R. (1982). The tectonic significance of Triassic dolomite and cargneule in the Gran Paradiso region, Western Alps. Geol. Mag., 119 (3), 301-308. - Venturelli, G., Thorpe, R.S., Dal Piaz, G.V., Del Moro, A. & Potts, P.J. (1984). Petrogenesis of calc-alkaline, shoshonitic and associated ultrapotassic Oligocene volcanic rocks from the Northwestern Alps, Italy. Contrib. Mineral. Petrol ., 86, 209-220. - Venturini, G. (1995). Geology, Geochemistry and Geochronology of the inner central Sesia Zone (Western Alps - Italy). Ph.D. Thesis, Mém. Géol., (Lausanne), 25, 1-136. - Venturini, G., Martinotti, G., Armando, G., Barbero, M. & Hunziker, J.C. (1994). The central Sesia Lanzo Zone (western Italian Alps), new ﬁeld observations and lithostratigraphic subdivisions. Schweiz. mineral. petrogr. Mitt ., 74, 115-125. - Venturini, G., Hunziker, J.C. & Pfeifer, H.R. (1996). Geochemistry of mafic rocks in the Sesia Zone (Western Alps): New data and interpretations. Eclogae geol. Helv., 89, 369-388. - Vercesi, P.l., Falletti, P., Pasquini, C., Papani, L., Perotti, C. & Tucci, G. (2012). Note illustrative, Foglio 178 Voghera della Carta Geologica d’Italia alla scala 1:50.000. ISPRA, Servizio Geologico d’Italia, Roma, 1-166. - Vialon, P. (1966). Etude géologique du massif cristallin Dora-Maira, Alpes cottiennes internes, Italie. Thèse de Doctorat d’Etat, Trav. Lab. Géol. Grenoble, Mém., 4, 293 p. - Vigna, B., Fiorucci, A. & Ghielmi, M. (2010). Relations between stratigraphy, groundwater flow and hydrogeochemistry in Poirino Plateau and Roero areas References 141

of the Tertiary Piedmont Basin, Italy. Mem. descr. Carta Geol. It ., 90, 267-292. - Violanti, D. (2012). Pliocene Mediterranean Foraminiferal Biostratigraphy: A Synthesis and Application to the Paleoenvironmental Evolution of Northwestern Italy. In: Ö. Elitok (Ed.). Stratigraphic Analysis of Layered Deposits, Intech, 123-160. - Violanti, D. & Giraud, V. (1991). Contributi allo studio del Neogene delle Langhe sud-occidentali (Mondovì). Riv. It. Paleont. Strat., 97 (3-4), 639-660. - Violanti, D., Dela Pierre, F., Trenkwalder, S., Lozar, F., Clari, P.A., Irace, A. & d’Atri, A. (2011). Biostratigraphic and palaeoenvironmental analyses of the Messinian/Zanclean boundary and Zanclean succession in the Moncucco quarry (Piedmont, Northwestern Italy). Bull. Soc. géol. France, 182 (2), 149-162. - von Blanckenburg, F. & Davies, J.H. (1995). Slab breakoff. A model for syncollisional magmatism and tectonics in the Alps. Tectonics , 14, 120-131. - Warrak, M. (1974). The petrography and origin of dedolomitized, veined or brecciated carbonate rocks, the «cornieules», in the Fréjus region, French Alps. J. Geol. Soc., London, 130, 229-247. - Wieland, H. (1966). Zur Geologie und Petrographie der Valle Isorno (Novara, Italia). Schweiz. mineral. petrogr. Mitt., 46, 189-303. - Wirth, R. (1986). Thermal alteration of glaucophane in the contact aureole of the Traversella intrusion (North Italy). Neues Jahrb. Mineral. Abh., 154 (2), 193-205. - Zaccagna, D. (1887). Sulla Geologia delle Alpi Occidentali. Boll. R. Com. Geol. It., 18, 346-417. - Zanetti, A., Mazzucchelli, M., Sinigoi, S., Giovanardi, T., Peressini, G. & Fanning, M. (2013). SHRIMP U-Pb zircon Triassic intrusion age of the Finero Mafic Complex (IVZ, Western Alps) and its geodynamic implications. J. Petrol ., 54, 2235-2265. - Zanetti A., Mazzucchelli, M., Sinigoi, S., Giovanardi, T., Peressini, G. & Fanning, M. (2014). Erratum. SHRIMP U-Pb zircon Triassic intrusion age of the Finero Mafic Complex (IVZ, Western Alps) and its geodynamic implications. J. Petrol ., 55, 1239-1240. - Zanoni, D. (2010). Structural and petrographic analysis at the north-eastern margin of the Oligocene Traversella pluton (Internal Western Alps, Italy). It. J. Geosci., 129, 51-68. - Zanoni, D. (2016). Structure and petrography of the southwestern margin of the Biella pluton, Western Alps, J. Maps, 12 (3), 597-620. - Zanoni, D., Spalla, M.I., Gosso, G. & Zucali, M. (2007). Emplacement of late-collisional plutons in exhumed deep crustal slices: The case of the Sesia- Lanzo Zone (Internal Western Alps). Rend. Soc. Geol. It., 5, 228-230. 142 References

- Zezza, U. (1977). Studio petrografico del massiccio granitico del Biellese. Atti Soc. It. Sci. Nat., 118, 65-102. - Ziegler, P.A. & Stampfli, G.M. (2001). Late Palaeozoic-Early Mesozoic plate boundary reorganization: Collapse of the Variscan orogen and opening of Neotethys. In: G. Cassinis (Ed.). Permian Continental Deposits of Europe and Other Areas. Regional Reports and Correlations. Natura Bresciana , Ann. Mus. Civ. Sci. Nat. Brescia, 25, 17-34. - Zingg, A. (1983). The Ivrea and Strona-Ceneri zones (Southern Alps, Ticino, N-Italy) - a review. Schweiz. mineral. petrogr. Mitt., 63, 361-392. - Zingg, A., Hunziker, J.C., Frey, M. & Ahrendt, H. (1976). Age and degree of metamorphism of the Canavese Zone and of the sedimentary cover of the Sesia Zone. Schweiz. mineral. petrogr. Mitt., 56, 361-365. - Zingg, A., Handy, M. Hunziker, J.C. & Schmid, S.M. (1990). Tectono- metamorphic history of the Ivrea Zone and its relationship to the crustal evolution of the Southern Alps. Tectonophysics , 182, 169-192. - Zucali, M., Cantù, M. & Spalla, M.I. (2012). Contrasting tectonometamorphic evolutions in the southern Sesia-Lanzo Zone (Rocca Canavese Thrust Sheets, Western Austroalpine domain) inferred by multiscale structural analysis. Rend. online Soc. Geol. It., 22, 247-250.

Oﬃ cial Geological Maps of Reference

- Servizio Geologico d’Italia (Italian Geological Survey), Sheets n. 132-152- 153 «Bardonecchia»; n. 154 «Susa»; n. 155 «Torino Ovest»; n. 156 «Torino Est»; n. 157 «Trino»; n. 171 «Cesana Torinese»; n. 178 «Voghera»; n. 194 «Acqui Terme»; n. 196 «Cabella Ligure»; n. 211 «Dego»; n. 213 «Genova»; n. 214 «Bargagli»; n. 228 «Cairo Montenotte» of the Italian Geological Map, at 1:50,000 scale, ISPRA, Rome, on-line resource http://sgi.isprambiente.it/ geoportal/catalog/sgilink/map50k.page - Servizio Geologico d’Italia (Italian Geological Survey), Sheets n. 30 «Varallo» (1 st ed., 1927); n. 41 «Gran Paradiso» (1 st ed., 1910); n. 42 «Ivrea» (1 st ed., 1910); n. 43 «Biella» (2 nd ed., 1966); n. 57 «Vercelli» (2 nd ed., 1969); n. 58 «Mortara» (2 nd ed., 1969); n. 67 «Pinerolo» (1 st ed., 1910); n. 68 «Carmagnola» (2 nd ed., 1969); n. 69 «Asti» (2 nd ed., 1970); n. 70 «Alessandria» (2 nd ed., 1970); n. 71 «Voghera» (2 nd ed., 1971); n. «78-79» Argentera-Dronero (2 nd ed., 1971); n. 80 «Cuneo» (1 st ed., 1920); n. 81 «Ceva» (2 nd ed., 1970); n. 82 «Genova» (2 nd ed., 1971); n. 91 «Boves» (1 st ed., 1934); n. 92-93 «Albenga-Savona» (2 nd ed., 1970) of the Italian Geological Map at 1:100,000 scale, Rome. - Consiglio Nazionale delle Ricerche (1990). AA.VV., Progetto finalizzato «Geodinamica». Structural model of Italy 1:500,000 scale. SELCA, Firenze. References 143

- Service hydrologique national de la Suisse (1999). Carte tectonique des Alpes de Suisse occidentale (1:100,000). Feuille 47 «Monte Rosa». - SwissTopo Office (2005). Geological Map of Switzerland, 1:500,000 scale , Wabern CH-3084: http://www.swisstopo.admin.ch/internet/swisstopo/it/ home/swisstopo/org/geology.html - Bureau de Recherches Géologiques et Minières (Geological Survey of France). Feuille 776 «Lanslebourg Mont-d’Ambin»; Feuille 872 «Aiguille de Chambeyron»; Feuille 896 «Larche»; Feuille 922-948 «Viève-Tende» de la Carte géologique de la France, 1:50,000 scale. - Bureau de Recherches Géologiques et Minières (Geological Survey of France)., Feuille NL 32-7 «Annecy»; Feuille NL 32-10 «Gap» de la Carte géologique de la France 1:250,000 scale. I 41 (a.a. 2016-2017)

Geological Map of Piemonte Region at 1: 250,000 scale Explanatory Notes F P, L B, R C, A ’A, G F, A I, P M, S T, G M e M M

Abstract ...... 3 Riassunto ...... 4 Acknowledgements ...... 5

1. Introduction ...... 5 Adopted controlled vocabulary and descriptive standards ...... 5 2. How to read the map ...... 7

3. Geological setting ...... 17 The Alps-Apennines orogenic system ...... 17 Main Geologic Events recognized at regional scale ...... 19 4. Criteria for geological classiﬁ cation and map representation . . . . . 26 Fundamental geological criteria ...... 26 Lithostratigraphic criteria – metamorphic and sedimentary rocks . . . . . 28 Subdivision of Sedimentary Units ...... 29 Subdivision of Metasedimentary Units ...... 30 Classiﬁ cation and representation of Quaternary successions ...... 30 Tectonic criteria (main tectonic contacts and faults) ...... 31 5. Brief outline of the Piemonte geology ...... 32

6. Description of the map legend ...... 35 Synorogenic basins ...... 35 The Quaternary succession ...... 35 The Pliocene succession and the Tertiary Piemonte Basin ...... 40 The Alpine foreland basin ...... 48 146 Summary

Units derived from the palaeo-European continental margin ...... 49 Sedimentary Units ...... 51 Metasedimentary Units ...... 60 Units derived from the polycyclic metamorphic basements and associated slivers of metasedimentary covers ...... 62 Units derived from the palaeo-European continental distal margin . . . . 72 Units derived from the Liguria-Piemonte oceanic domain ...... 74 «Non-metamorphic» units ...... 74 Metamorphic units ...... 76 Units derived from the Valais domain ...... 78 Units derived from the palaeo-Adriatic continental margin ...... 78 The Austroalpine domain ...... 78 The Southalpine domain (Southern Alps) ...... 80 Tectonic slice Zones ...... 85 Canavese Zone ...... 85 Sestri-Voltaggio Zone ...... 86 Alpine synorogenic magmatic bodies and dykes, and associated volcano- sedimentary covers ...... 87 Biella Pluton (Valle del Cervo Pluton) ...... 87 Miagliano tonalite Pluton ...... 88 Brosso-Traversella Pluton ...... 89 Biella volcano-sedimentary suite («Biella Volcanic Suite») ...... 89 Other features in the map legend ...... 90 Fault rocks ...... 90 Undiﬀ erentiated sedimentary and metasedimentary units preserved along the main tectonic contacts ...... 90 Man-made deposits ...... 91 Symbols ...... 91 7. Methods for Map Representation and Data Base management. . . . . 92

8. The Topographic base of the Piemonte Geological Map ...... 92

References ...... 93

Direttore responsabile: Massimo Mori Autorizzazione del Tribunale di Torino n. 2685 del 13 aprile 1977 Iscrizione al R.O.C. n. 2037 del 30 giugno 2001

Finito di stampare nel mese di ...... da...... s.r.l. Anno di fondazione della rivista: 1759 Direttore responsabile: Massimo Mori Autorizzazione del Tribunale di Torino n. 2685 del 13 aprile 1977 Iscrizione al R.O.C. n. 2037 del 30 giugno 2001

Finito di stampare nel mese di dicembre 2018 da Cialab - Ascoli Piceno