HAL Id: insu-01265777
https://hal-insu.archives-ouvertes.fr/insu-01265777
Submitted on 1 Feb 2016
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
from the Saraillé Massif (Chaînons Béarnais, North-Pyrenean Zone)
Benjamin Corre, Yves Lagabrielle, Pierre Labaume, Serge Fourcade, Camille Clerc, Michel Ballèvre
To cite this version:
Benjamin Corre, Yves Lagabrielle, Pierre Labaume, Serge Fourcade, Camille Clerc, et al.. Defor- mation associated with mantle exhumation in a distal, hot passive margin environment: New con- straints from the Saraillé Massif (Chaînons Béarnais, North-Pyrenean Zone). Comptes Rendus Géo- science, Elsevier, 2016, From rifting to mountain building: the Pyrenean Belt, 348 (3-4), pp.279-289.
�10.1016/j.crte.2015.11.007�. �insu-01265777�
Tectonics, Tectonophysics
Deformation associated with mantle exhumation in a distal, hot passive margin environment: New constraints from the Saraille´ Massif (Chaıˆnons Be´arnais, North-Pyrenean Zone)
Benjamin Corre
a,*, Yves Lagabrielle
a, Pierre Labaume
b, Serge Fourcade
a, Camille Clerc
c, Michel Balle`vre
aaGe´osciencesRennes–UMR6118,universite´ deRennes1–CNRS,263,avenueduGe´ne´ral-Leclerc,CS74205,35042Rennescedex,France
bGe´osciencesMontpellier–UMR5243,universite´ deMontpellier–CNRS,placeEuge`ne–Bataillon,CC60,34095Montpelliercedex5,France
cInstitutdessciencesdelaterred’Orle´ans–UMR7327,universite´ d’Orle´ans,1A,ruedelaFe´rollerie,45071Orle´anscedex2,France
1. Introduction
Subcontinentalmantlerocksareexhumedatthefootof somepresent-daynonvolcanicdistalpassivemarginsdue
toextremethinningofthecontinentalcrust.Inthedeep ocean, the rocks recording the processes of mantle exhumationareofverylimitedaccess.Therefore,thestudy ofinvertedpassivemarginsexposedinmountainbeltsisof highinterest(ClercandLagabrielle,2014;Mohnetal.,2015;
Pe´ron-PinvidicandManatschal,2009;Tugendetal.,2014).
Suchanaloguesallowdirectsamplingofagreatvarietyof rocksintheenvironmentwheremantlerocksareexhumed.
ARTICLE INFO Articlehistory:
Received22August2015
Acceptedafterrevision15November2015 Availableonlinexxx
HandledbyMargueriteGodard Keywords:
Ductiledeformation Albian–Cenomanianrifting Distalpassivemargin Mantleexhumation ChaıˆnonsBe´arnais
ABSTRACT
TheChaıˆnonsBe´arnaisranges(North-PyreneanZone,west-centralPyrenees)displaya fold-and-thruststructureinvolvingtheMesozoicsedimentarycover,decoupledfromits substratumattheKeuperevaporiteslevelandassociatedwithafewperidotitebodiesand scarcePalaeozoicbasementlenses.InthewesternpartoftheChaıˆnonsBe´arnais,thenewly describedrecumbentfoldoftheSaraille´ massifcomprisesaperidotitebodyandseveral lensesofPalaeozoicbasementwrappedbytheTriassictoAptiansedimentarycover.This structurerepresentsaremnantofthedistalportionofthePyreneanpaleo-riftedmargin wheremantlerockshavebeenexhumedduringAlbian–Cenomaniantimes.Inthispaper, wepresentthefirstdetailedmappingandmicrostructuralanalysisoftheSaraille´ massif, providingnewgeologicalbasisforreconstructingtheevolutionofthispartofthepaleo- margin.Ourmapping(i)showsthatthepre-riftMesozoiccoverformsarecumbentfold coredbymantleandcrustalrocksand(ii)confirmsthatthepreriftcoverwasdetached fromitsbedrockalongalayerofTriassicevaporitesandslidontotheexhumedmantle rocks.Slidingofthepreriftcoverwasassociatedwithextremecrustalthinningandmantle exhumation along a major detachment fault, together with intense metasomatism affectingboththecontinentalbasementandthesedimentarycover.Weshowforthefirst time(1) that theMesozoic pre-rift sediments experienced syn-metamorphic ductile thinningduringmantleexhumation,and (2)thatduring itsextremeattenuation,the continentalbasementwasreducedtotectoniclensessometenmetersthickbyductile shearing.
ß2015Acade´miedessciences.PublishedbyElsevierMassonSAS.Thisisanopenaccess articleundertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/
4.0/).
* Correspondingauthor.
E-mailaddress:benjamin.corre@univ-rennes1.fr(B.Corre).
ContentslistsavailableatScienceDirect
Comptes Rendus Geoscience
w ww . sc i e nce d i re ct . co m
http://dx.doi.org/10.1016/j.crte.2015.11.007
1631-0713/ß2015Acade´miedessciences.PublishedbyElsevierMassonSAS.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http://
creativecommons.org/licenses/by-nc-nd/4.0/).
ThePyreneesareaneast-west-trendingbeltresulting from the tectonic inversion of a thinned continental domainopenedbetweentheIberianandEuropeanplates duringmid-Cretaceoustimes(Choukroune,1992).They comprisethreemaindomains,theNorth-PyreneanZone (NPZ),theAxialZone(AZ)andtheSouth-PyreneanZone (SPZ)(Fig.1a).TheNPZiscomprisedofafoldedMesozoic sedimentarycover,locallymetamorphosed.Theeastern andcentral parts of the NPZ are characterized by the occurrenceofmassifs ofPalaeozoicrocks,theso-called theNorth-PyreneanMassifs.The AZis mostly madeof Variscanmeta-sedimentsandgranitoids.TheSPZismade ofthefoldedMesozoicandCenozoicsedimentarycover detached on the Triassic evaporites. The Cretaceous extension in the Pyrenean realm resulted from the rotationalplatemotionofIberiaversusEurope,inrelation withthe openingof the NorthAtlantic andtheBay of Biscayoceanicdomains(e.g.,ChoukrouneandMattauer, 1978;Gongetal.,2008;Olivet,1996;Sibuetetal.,2004).
Sofar,severalkinematicmodelshavebeenproposedto describe the Iberia rotation. These models provide differentconstraintsfor the age,amount anddirection of crustal extension andfor the width of the thinned domain(Jammes et al.,2009, 2010;Mouthereauet al., 2014,Teixelletal.,2016;Tugendetal.,2014).However,a general consensusexistsonthefact thatmantlerocks havebeenexhumedonthefloorofAlbian–Cenomanian basinsastheresultofextremecontinentalthinning.These basins were inverted by the Pyrenean orogeny from theLateSantoniantoEarlyMiocenetimestoform the futureNPZ(e.g.,Mouthereauetal.,2014;Mun˜ oz,1992;
Roureetal.,1989;Verge´setal.,2002;Teixelletal.,2016).
Asaconsequence,thePyreneanbeltisnowconsideredasa relevantanalogueofpreorogenicpassivemargins(Clerc etal.,2012,2013;Jammesetal.,2009,2010;Lagabrielle andBodinier,2008;Lagabrielleetal.,2010;Teixelletal., 2016).
TheIberianandEuropeandistalmarginsarecharac- terised by a regime of hyperextension implying the exhumationof the subcontinental mantle, thetectonic lenticulation of the continental crust and the detach- mentofthesedimentaryMesozoiccover(Jammesetal., 2010; Lagabrielle et al., 2010). Recently, Clerc and Lagabrielle (2014) have proposed that owing to the high thermal gradient accompanying mantle exhuma- tion, the crustal and sedimentary cover rocks of the distal partof thehyperextended marginsbehaved in a ductile manner. Therefore, an important issue is to better investigate the significance of the relationships between mantlerocks,continentalbasementrocksand Mesozoic metasediments that are exposed together in the NPZ. In this paper, we present a new detailed geological study of the Saraille´ Massif (Chaıˆnons Be´arnais ranges, west-central NPZ; Fig. 1), a key area where mantle rocks, continental basement rocks and pre-andsyn-riftsedimentsareexposedoverarestricted area.Despiteitsimportanceinunravellingfundamental processes (Lagabrielle et al., 2010), the geology of the Saraille´ massifhasbeenlittleinvestigated;inparticular, adetailedgeologicalmapat1/25,000scalewaslacking.
Here,weprovidethisdetailedmappingandwediscuss its implications for the processes related to mantle exhumation accompanying extreme continental thin- ningin thePyreneandomain.
Fig.1.a.StructuralmapofthePyrenees.NPFT:North-PyreneanFrontalThrust,NPF:North-PyreneanFault,SPF:South-PyreneanFault,SPFT:South PyreneanFrontalThrust(afterVauchezetal.,2013).b.StructuralmapoftheChaıˆnonsBe´arnaisregion,withlocationofthepanoramicviewofFig.2andof mapinFig.3(rectangle)(afterCaste´ras,1970andLagabrielleetal.,2010).
2. Geologicalsettingandpreviousresults
2.1. TheNorth-PyreneanZone(ZNP)
TheNPZshowsthreemajorgeologicalfeatures.
(1)ThemetamorphicMesozoicsedimentsareintimately associated with fragments of subcontinental mantle rocksandwithverythintectoniclensesofcontinental basementrocks.
(2)TheMesozoicsedimentsweremetamorphosedatlow pressure and high-to veryhigh-temperature condi- tionsduringtheAlbo-Cenomanianextension(Albare`de andMichard-Vitrac,1978;ChoukrouneandMattauer, 1978; Golbergand Leyreloup,1990). In thewestern Pyrenees, the maximal temperaturerecorded in the metasedimentsreachesca.3508Candwasmeasuredin Albiansediments of theSaraille´ massif (Clercet al., 2015). The Cretaceous metamorphism was thus synchronous withextreme continental thinning and mantleunroofing.
(3)TheCretaceousriftingledtotheopeningofbasinsfilled withflysch-typesediments.Openingstartedduringthe Albian with disconnected basins filled withthe so- calledFlyschNoir;thesebasinswerelaterconnected intoawidertroughduringtheCenomanian(Debroas et al., 2010). A significant feature is that, during extension,theTriassictoAptianshallowwaterprerift sedimentsweredecoupled fromtheirbasement and weresetintectoniccontactontopofthemantlerocks.
Suchadecouplingofthesedimentarycoverwascaused eitherby(1)gravityslidingofsedimentraftsintothe basins,orby(2)traction-assistedslidingduringlateral extractionoftheductilecrust(ClercandLagabrielle, 2014).
2.2. TheChaıˆnonsBe´arnais
TheChaıˆnonsBe´arnaiscorrespondtoasegmentofthe west-centralZNP,formingaseriesofE/W-trendingfold- thruststructuresintheMesozoicsuccession,flooredbya south-verging Pyrenean de´collement in the Triassic evaporites (Teixell et al., 2016). In their western part, theChaıˆnonsBe´arnaiscomprisefromnorthtosouth:the south-verging Mail Arrouy thrust and the Sarrance anticlineandthenorth-vergingLayensanticline(Caste´ras, 1970) (Fig. 1b). The base of the Mesozoic sequence is represented by the Triassic Keuper facies with shales, evaporites, breccias andophites, followedbyJurassicto Aptian platform limestones and dolomites, and Upper JurassicAptianlimestones,withshaleintercalationsinthe UpperLiassic andLowerAptian.Thesesedimentsrepre- sent the original prerift cover of the northern Iberian margin(Cane´rotandDelavaux,1986;Cane´rotetal.,1978), now entirely detached from its original Palaeozoic basement (Lagabrielle et al., 2010; Teixell et al., 2016).
The syn-rift Albian–Lower Cenomanian Flysch Noir is preservedwithinthesynclines.Thissedimentarysucces- sion isintimately associated withperidotite(lherzolite) bodiesandscarcePalaeozoicbasementexposures,mostof
them located at the base of the Mesozoic sequence (Fig.1b).Themantlerockswereincorporatedduringthe Cenozoicinthetectonicwedgeastheresultoftheclosure oftheunroofedmantledomain.Asawhole,theChaıˆnons Be´arnaiswedgerepresentsthesuturebetweentheIberian andtheEuropeanplates(Lagabrielleetal.,2010;Masini etal.,2014,Teixelletal.,2016).
Fourmainlherzolitebodiesareexposedinthewestern ChaıˆnonsBe´arnais(Fig.1b):(1)theSaraille´ and(2)theTos delaCoustettebodiesinthecoreoftheSarranceanticline, (3)theTurondelaTe´coue`rebodyatthebaseoftheMail Arrouythrustunit,and(4)theUrdachbodyatthewestern endoftheMailArrouy.Inthispaper,wereporttheresults ofdetailedinvestigationsontheSaraille´ massifwherethe mostcompletecollectionoflithologiesisexposed.
2.3. TheSaraille´ massif
TheSarranceanticlinedisplaysafoldedMesozoiccover andtwoperidotitebodiesassociatedwithtectoniclensesof Palaeozoicrocks,outcroppingrespectivelyintheTosdela CoustetteandtheSaraille´ massif(Caste´ras,1970)(Fig.1b).
In the Saraille´ massif, the comprehensive association of mantlerocks, Palaeozoic basement rocksand Triassic to Albian metasediments forms a unit, 1km1km wide, thrustsouthwardsoverthe AlbianFlyschNoir.Thisunit correspondstofoldedMesozoicmetasedimentswrapping bothmantleandcrustalrocks(Fig.2).
The1/50 000 scalegeologicalmap of Oloron-Sainte- Marie(Caste´ras,1970)providesabriefdescriptionofthe peridotitebodies of the Sarrance anticlinewith a short interpretation of their geological setting. Following this first description, the peridotite bodies have been the subjectofdifferentinterpretations:
(1)theyhavebeenfirstregardedastheresultofanearly exhumationduringtheMid-Jurassictimes,followedby thedepositionofunconformableMesozoicsediments over aseafloorcomprisingultramaficand Palaeozoic crustalrocks(Due´eetal.,1984;Fortane´ etal.,1986);
(2)peridotite uplift along Mesozoic faults and their incorporation with a slice of Palaeozoic rocks into the sedimentary cover during theCenozoic tectonic inversionoftheNPZhasbeenproposedbyCane´rotand Delavaux(1986);
(3)the contact between the mantle rocks and the Mesozoic sediments has been attributed to detach- mentfaultingduringtheAlbo-Cenomanianextension- alphase,withthePalaeozoiclenscorrespondingtoa remnantofthehyper-extendedcrust(Lagabrielleetal., 2010).
TheperidotitesoftheSaraille´ massifforma500m-long and 100m-thick lens-shaped body overlying 10–20m- thicktectoniclensesofvariouscontinentalrocks.Boththe mantle body and thecontinental lenses are in tectonic contact withtheMesozoicsediments. Atthetopof the lherzolite body, the contact withJurassic dolostones is outlinedbyalenticular,stronglysheared,talc-richlayerup to15mthick(Lagabrielleetal.,2010).Asdiscussedbelow, this layer is thought to be the record of intense fluid
circulationscoevalwithmantleexhumation.TheSaraille´
mantlerocksaremadeoftwotypesofperidotites:spinel- lherzolitesandpyroxenites,mostlywebsterite.Pyroxeni- tesarerepresentedbynumerouscentimetre-thickparallel layerswithinthelherzolitebody.Theselayersarepartof anearlymantlehistoryofthelherzolite(Gaudichet,1974) andareassociatedwithrefertilisationprocessesidentified inothermantlebodiesoftheNPZ(LeRouxetal.,2007).
Refertilisationby secondarymelts,firstdescribedin the Lherzmantlebody(centralNPZ),involvesadditionofCpx and dissolution of Ol at the expense of a primary harzburgite. Such a phenomenon is thought to have occurredduringtheascentofthemantleinextensional contextinlithosphericconditions(KaczmarekandMu¨n- tener,2010;LeRouxetal.,2007;Mu¨ntenerandPiccardo, 2003). The Saraille´ lherzolites are highly serpentinized withchrysotile and lizardite as dominant (95%) phases (Ferreira,2013).Thetemperatureofthefluidsresponsible for the mantle hydration is estimated at ca. 1758C (Ferreira,2013).Inaddition,theserpentinitesarecrosscut bylateantigoriteveins,resultingfromthecirculationof metamorphicfluids(Ferreira,2013).
2.4. MetamorphicevolutionoftheSaraille´ massif
Gaudichet(1974)revealedthepresenceofametamor- phic mineral association of newly-formed muscovite, chloriteandalbite,observedinthewholeMesozoiccover oftheSarranceanticline,includingtheAlbianFlyschNoir.
In addition,thisauthor showedthattheAlbianflyschis characterized by the development of at least two cleavages.Theearliestone(S1),paralleltobedding (S0), isunderlinedbythealignmentofsyn-kinematicmuscovite andchloriteflakes.Themetamorphicimprintishomoge- neousacrosstheSarranceanticlineandthereisnoincrease of the metamorphic conditions towards the Saraille´
lherzolite body. In their first detailed mapping of the Saraille´ massif,Fortane´ etal.(1986)describedthefoliated talc-rich layer located between the lherzolites and the Mesozoicsediments.Theyevidencedthepresenceoftalc, clinochlore and pyrite, an association representative of greenschist facies conditions (250–3508C). Similartem- peratures have beenobtained recentlyby Raman spec- trometry analysis of organic matter in the Aptian limestones and Albian flysch, the highest temperature being foundclosetotheSaraille´ lherzolite (Clercet al., 2015).
3. LithologyandstructureoftheSaraille´ massif:new results
3.1. Generalstructure
AsshownonthepanoramainFig.2andonthemapand cross-sectionsinFig.3,ourfieldinvestigationsrevealthat the structure of the Saraille´ massif corresponds to a recumbentfoldofMesozoicsedimentarycoverwrapping themainlens-shapedunitofmantlerocksandassociated Fig.2.InterpretedpanoramaoftheSaraille´ massifseenfromtheLourdiossyncline(seeFig.1).
slices of Palaeozoic basement rocks. These Palaeozoic lensesalsofollowthefoldgeometry,butareabsentatthe upper contact of the peridotite body, which is there directlyagainstthesedimentarycover.Thegeometryof thefoldedMesozoiccoverexhibitsaverystrongasymme- try between the normal and the reverse limbs, with stretchingofthereverselimbshownbytheconsiderable thicknessreductionofthecarbonatesequence.Othersmall lensesofcrustalandmantlerocksoccurinthenorthern partofthemassif(Lau¨ndePass;Fig.3).Themantlerocks, thecontinentalbasementrocksandthesedimentarycover areallseparatedfromeachotherbytectoniccontacts.
Onitsnortheasternside,theSaraille´ massifrestsabove brecciated Triassic sediments forming the core of the Sarranceanticline.BoththeSaraille´ massifandtheTriassic sedimentsarethrustsouthwardsabovetheAlbianFlysch NoiroftheLourdios synclinebyasubhorizontalcontact (Caste´ras,1970;Lagabrielleetal.,2010).
3.2. Basementrocks
Ourmappingrevealsthatvariouslithologiesfromthe continental crust form thin, elongated tectonic lenses
exposedbeneathandsouthofthemainmantlebodyonthe westernflankofthemassifand,tothenorth,inapoorly exposed area at theLau¨ndepass (Fig. 3a). Thewestern lensesdisplayawell-developedtectonicfoliation(Plate1A) parallelingthe contactwith theperidotites(Fig.3b).We collectedtwenty-sixsamplesfromthesecrustallensesfor microscope study. Seventeen samples are quartz-rich mylonites orchlorite-and mica-rich mylonites, deriving fromPalaeozoicmetasediments(Plate1,BandC).Locally, themyloniticfoliationiscrosscutandoffsetbydecametric brittle faults and by cataclastic shear bands. Weakly deformed metasediments are rare: only one sample of quartziteandonesampleoffoldedmarblewerecollected.
The remaining nine samples are undeformed quartz- albititesandonesampleofgranite.
Numerous millimetre-to-centimetre-thick albitite veinlets and veinscross-cut the foliation in mylonites closetothecontactwithmantlerocks(Plate1C).Inthe eastern Pyrenees, albitites are known as a product of fluid/rock interactions duringa syn-extensionmetaso- matic event lasting ca.15 Ma between 100 and98Ma (Boulvaisetal.,2007;Fallourdetal.,2014;Poujoletal., 2010).
Fig.3. a.DetailedgeologicalmapoftheSaraille´ massif.b.Stereogram(southernhemisphere)showingtheattitudeofthepyroxeniticlayeringinthe lherzolites(greenlines)andthefoliationofthePalaeozoicbasement(redlines)alongthewesternboundaryofthemantlebody.c.NW–SEcross-section alongtheSaraille´ massif.SeeFig.1forlocation.Letters:locationofphotographsshowninPlate1.
Plate1. OutcroppicturesoftheSaraille´ massifandselectedthinsectionsofrocksfromthecrustalbasement,themantlerocksandtheMesozoicmeta- sediments(seeFig.3forlocations):A.MyloniticPalaeozoicbasement.B.UltramyloniteinPalaeozoicmetapelite.C.MyloniticPalaeozoicfelsicrockcrosscut byundeformedalbititeveinlets.D.Jurassicdolomiteshowingflatteningofvariousbiogenicdebrisanddifferentpopulationsofcarbonateveinletsparallelto orcuttingthefoliation.E.Detailedviewofthebasalcontactoftheperidotitebody,showingthecataclasticcorezoneinitslowerpart.F.Detailviewofthe corezone,featuringacataclasticphacoidalfabricinmixedperidotiteandsialicrockfragments.G.Damagedzoneofthecontactfeaturingfracturesurfaces definingam-scalephacoidalfabricattherimofthemantlebody,afewmetresabovethecontact.H.Foliatedtalc-richzoneinJurassicdolomiteincontact withthechlorito-talcschistlayer.
3.3. Sedimentarycover
The upper part of the Saraille´ massif consists of a MesozoicsequenceincludingTriassictoAlbianmetasedi- ments(Fig.3).TheTriassicispoorlyexposednorthofthe massif and seems to be tectonically dismembered. It includesmotleycalcschists,cellulardolomite,brecciated limestonesaswellasdolostonesandophites.Ophiteisa tholeiiticmaficigneousrockofdoleritetype,characteristic of Triassicmagmaticevents (Caste´ras,1970).Abovethe mainperidotitebody,themetasedimentarycoverisbase- missingandbeginsbyalayerofJurassicdolomiteuptoone hundredmetersthick.Thisdolomitelayercancorrespond totheCallovian–Oxfordian,butwithalightergreycolour and a finer grain size than its regional facies. The Kimmeridgian–Neocomian corresponds to an up to 40m-thick alternation of decimetre-thickbeds of dolo- mite, limestones and phyllite-rich limestone.Thethick- nessofthelatterismuchlowerthantheregionalthickness (250minthenorthernlimboftheSarranceanticline).The UpperAptian isrepresented byUrgonianfaciesplatform limestoneslargelyexposedonthetopandsouthernflankof theSaraille´ massif(Fig.2).TheAlbianFlyschNoirfollowsthe Urgonianlimestonesonthesouth-easternflankofthemassif andliesbelowthesolethrustofthemassif.Itcomprisesan alternationofblackmarls,siltsandlimestones.
TheJurassictoAptiancarbonatesarestronglyrecrys- tallized,aswellastheAlbianlimestonesonalocalscale.In the entire Mesozoic sequence, a S1 foliation always parallelsthestratigraphicbedding (S0).Thefoliation,of variableintensity,isdefinedbytheflatteningofpaleonto- logicalandsedimentologicalobjectssuchasmacrofossils, microfossilsandbiogenicclasts,perpendiculartotheS0 plane. At the thin-section scale, flattening is not only observedindiscretedeformedbandsparallelingS0,butit canalsoaffecttheentirerockasobservedinthecarbonates sampledclosetothebasalcontactwiththemantlerocks (e.g.,SAR5Plate1D).Thelongestcalciteveinsobservedin the carbonates parallel S0 and therefore also underline the foliation. A striking feature is that these veins are boudinaged, indicating extension in the S0/S1 plane consistentwiththeoveralldeformationpattern.Younger smallveinscutobliquelytotheS0/S1planes.TheAlbian limestonebeds inthe footwallofthe thrustalsofeature prefoldingstrongboudinagewiththickinterboudinquartz and calcite veins. As a whole, this deformation pattern suggests anearlyflatteningof the sedimentarypilethat occurredduringtheAlbo-Cenomanianextensionalphase.
3.4. Natureofthecontacts
3.4.1. Contactbetweenmantlerocksandcontinental basement
The Saraille´ massif displays a spectacular tectonic contact between mantlerocks and Palaeozoicbasement rocks(Cane´rotandDebroas,1988;Cane´rotandDelavaux, 1986;Due´eetal.,1984;Fortane´ etal.,1986;Lagabrielle et al., 2010). On the northern side of the massif, serpentinites outcropping along theroad to the Col de Saudarieoverlygneissic granitoidsand acidicmylonites lenses.Thegeometryasa‘‘reversedMoho’’resultsfromthe
folding of an original assemblage where the mantle rocksoccurredatthebase.Thecontactisasharpsurface (Plate 1E), but it is included into a deformation zone several tens of metres in thickness. Below the main contact,themetre-thickcorezoneofthefaultisabreccia made of a mixing of ultramafic and sialic grains and featuringdecimetre-scalephacoids(Plate1,EandF).Thin sections in themantle rocks close to themain contact (Fig. 1E, upper part) show millimetre-scale phacoids composed of cataclastic grains from the mantle rocks (serpentinizedolivine,pyroxenesandspinel)cementedby intergrowthofphylliticmaterial,mostlytalcandgreento pale chlorite associated with numerous pyrite grains.
Thesenewlyformedmineralsresultfromfluidcirculationin greenschist facies conditions and outline the pervasive foliation.Abovethecontact,theserpentinitesfeatureaten- meterthick damagezonewith discretefracturesurfaces coatedbyfibrousserpentiniteandformingphacoidsatthe meter scale (Plate 1G). Hence, the deformation zone is characterizedbya phacoidalfabricatvariousscalesand dominantcataclasticdeformationmechanisms.Theplanar fabricofthephacoidsisparalleltothemaincontactand theirshapeissymmetrical,suggestingdeformationinapure shearratherthaninasimpleshearregime.Owingtothe thicknessofthedeformationzone,tothedevelopmentofa metamorphicparagenesisinthefoliationplanesandtothe fact thatthe NPZ has recorded a HT–BPmetamorphism during Albo-Cenomanian times, this deformation can beregarded asa consequenceof the exhumation ofthe mantlerocksduringthe prealpinestagesand notasthe simple result of the Pyrenean thrust. A detailed micro- tectonic and mineralogical analysis of this contact is in progress.
3.4.2. Contactbetweenmantlerocksandprerift metasediments
Thecontactbetweenthemantlerocksandtheprerift metasedimentsisalsoatectoniccontact(Lagabrielleetal., 2010).Thisinterfaceisoutlinedbyadiscontinuouslayerof reactionalrocksthatcanbefollowedfromthesouthernto thenorthernsideofthemassifatthebasisoftheJurassic dolomites(Fig.3).Onthenorthernside,atectoniclensof layered brown Mg-rich carbonates overlies a strongly tectonizedassemblageofTriassicmetabreccias,cataclastic andmassiveophitesandtalc-richyellowschists,thelatter probablyderiving from theextreme shearing ofmantle rocks.Onthesouthernside,thelargestmineralizedlensis a 100m-long-per-10m-thick body of strongly schistose pink talc-rich rock showing a strong phacoidal fabric similartothefabricobservedalongthebasalcontactofthe mantlebody.Thisrockiscomposedofanassociationof talc,clinochloreandpyriteshowingapervasivefoliation, withrarerelictsofcataclasticpyroxenes.Dolomitegrains arefrequentbetweenthephylliticminerals(Plate1,H).
Microprobeanalyses of chlinochlore from this chlorito- talcschist are available in Fortane´ et al. (1986). Talc is known to form in greenschist facies conditions by alteration of ultramafic rocks (Abzalov, 1998) and/or dolomites (Blount and Vassiliou, 1980) favoured by an intensecontributionofSi-richfluids.Thefoliationofthe chlorito-talcschistis paralleltothecontact betweenthe
mantle body and the platform carbonates and bears a north–southlineation.Moreover,asdiscussedabove,the carbonates lack their stratigraphic base and show a pervasive bedding-parallel foliation subparallel to the contact(Plate1D).Asawhole,thesefeaturesarguethatthe mantle/sedimentscontactwasasyn-metamorphicexten- sionalshearzone, whereextensive fluidcirculation and metasomatismatratherhightemperature(upto3508C) ledtotheprecipitationofnewly-formedchlorite-talcschist (Plate1H).Theupwarddecreaseofdolomitizationinthe metasedimentary cover (cf. above) may also point to metasomatismrelatedtofluidcirculationinthecontact.
Suchaphenomenonhasbeenreportedfromthemetaso- matic system of Trimouns/La Porteille (Boulvais et al., 2006), where a thick talc/chlorite rich layer occurs betweenPalaeozoicmicaschistsanddolomites.
4. Discussion
4.1. EvolutionarymodeloftheSaraille´ Massif
Duringthe Albo-Cenomanian,theNPZdomainunder- wentextensionthatledtotheformationofpassivemargins astheresultofextremecrustalthinningandunroofingofthe subcontinental mantle (Jammes et al., 2009; Lagabrielle etal.,2010;Tugendetal.,2014;Masinietal.,2014,Teixell etal.,2016).TheSaraille´ massifisuniqueasitrecordsmost ofthesuccessivestagesofthetectonicprocessesleadingto crustal hyperthinning. Based on field observations and microscopicanalyses,ourstudyallowsustoreconstructan evolutionarymodelfortheseprocesses.
Firstly,asrevealedbythenatureofthecontactbetween mantlerocksandthesialicbasement,crustalthinninghas beenaccompanied by the activation of a major ductile detachmentfault(Fig.4).Motionalongthedetachmentled to the individualization of tectonic lenses at all scales, limitedbymyloniticshearbandsanddefiningaphacoidal fabric. The important lithological variety of the crustal rocksoftheSaraille´ massifcanbeexplainedbythefactthat tectoniclenticulationand extremethinningof thecrust predatedmantledenudation.Inotherwords,thecrustal rockshavebeensampledandleftalongthedetachment during the extensional phase to form a succession of discontinuouslensesabovethedenudatedmantle(Fig.4).
Ultimately, the detachment evolved toward cataclastic deformation due to exhumation processes in the latest stagesofrifting(Fig.1b).
Crustalthinningwassynchronouswiththeslidingof the sedimentary cover towards the distal parts of the margins, the Triassic evaporites playing the role of an efficientdetachmentlayer(Jammesetal.,2010)(Fig.4).In contrast to the nearby Urdach massif, the Saraille´
peridotitesneverformedtheseafloorof theextensional Cretaceous basin; they were only unroofed beneath extremely thinned basement rocks during the Albo- Cenomanian(Lagabrielleetal., 2010). Decouplingofthe sedimentary cover from its crustal basement occurred whilethecontinentalcrustunderwentlateralextraction between two convergent detachment faults located respectively at the mantle–basement interface and at the basement–cover interface (Clerc and Lagabrielle,
2014).Thepreriftsedimentsareintectoniccontactwith themantlerocksonlybetweenthetectoniccrustallenses.
Extensionalductiledeformationofthesedimentarycover alongthedetachmentfaultresultedinthedevelopmentof subtractive contacts associated with a strong bedding- parallelfoliationandadrasticthicknessreductionofthe stratigraphic pile. The detachment between the mantle rocks and thesedimentarycover has beenthelocus of intense metasomatic circulations responsible for the mineralizationofthetalc/chlorite-richlayer(Fig.4).The foliationofthislayerindicatessynkinematicdevelopment duringtheAlbian-Cenomanianriftingepisode.Therela- tivelyhightemperatureallowingtheductiledeformation of thesedimentarycover and thetalc-chlorite develop- mentwaspossiblethankstotwogeologicalprocesses:(1) theascentofthesubcontinentalmantlewhichcaused a steep geothermal gradient; and (2) the synchronous sedimentation of the Albian–Cenomanian flysch that probablyactedasablanketonthebasin,facilitatingthe temperatureincrease(Clercetal.,2015).
It still remains an important issue to decipher the timingoffoldingoftheSaraille´ massifstructure.Folding mayhaveoccurredduringtheextensionalphase(Albian–
Cenomanian) in relationwith salt tectonics(James and Cane´rot,1999),orduringthecompressionalphaseofthe PyreneanorogenystartingintheLateSantonian.
The Saraille´ talc/chlorite-rich layersharessomecha- racteristicswithmetasomaticlayersknownintheeastern Pyrenees suchasone ofthe largestdepositsoftalc ore worldwide, in the Saint-Barthe´le´my North-Pyrenean massif(Trimouns:Fortune´,1971;Moineetal.,1989).At Trimouns,the hydrothermalactivity responsibleforthe talcformationhasbeendatedbetween112Maand97Ma (Scha¨reretal.,1999).Itwasthuscontemporaneouswith theopeningoftheAlbian–Cenomanianbasins.However, this major ore deposit is located in a pure continental environmentincontrastwiththeSaraille´ massif.Toour knowledge,theSaraille´ massifistheonlyknownexample worldwide ofa preserveddetachment systeminvolving subcontinentalmantle,thinnedcontinentalbasementand preriftmetasediments.
4.2. TheSaraille´ massif:insearchofanalogues.Comparison withrecentpassivemargins
Nowadays,numerousmodelsofpassivemarginforma- tiondoexist(seereviewinHuismansandBeaumont,2011).
Recently,ClercandLagabrielle(2014)distinguishedacold riftedmarginmodelfromahotriftedmarginmodel.Inthe firstone,theproximalpartofthemarginischaracterizedby a system oftilted blocks andthe distal part exhibitsan exhumed mantle domain partly covered by continental allochthons.Thepreriftsedimentarycoverremainswelded onthetiltedblocksandonthecontinentalallochthons.A typical example of such a system is representedby the Galicia/Iberia margin(Boillotet al.,1995;Pe´ron-Pinvidic andManatschal,2009;Reston,2007).Thehotmarginmodel differsfromthecoldmarginonebyitsdistalpartwhere mantleisexhumedbetweenlensesofcrustdeformedina ductilemanner.Inthiscase,thepreriftsedimentarycoveris alsoaffectedbyasyn-metamorphicductiledeformation.
IntheSaraille´ massif,weobservedthefollowingmajor featuresconsistentwiththemodelofdistal,hotpassive marginswithexhumedmantle rocks proposed byClerc andLagabrielle(2014)forthepreorogenicPyrenees:(i)As aconsequenceoftheAlbian-Cenomanianriftingepisode, thesubcontinentalmantleisnowindirecttectoniccontact with the prerift sedimentary sequence. (ii) This prerift sedimentary sequence has experienced syn-extension
ductile deformation during the rifting along a major detachment.Features(i)and(ii)areboththeresultofthe lateralextractionofthecontinentalcrust,theuppercrust showinga ductilebehaviour.(iii)Thedetachmentfaults separatingthemantlerocksfromthepreriftsedimentsand fromthehyperthinnedcontinentalcrustwerethelociof intensehotfluidcirculationsproducingtalcand chlorite mineralizations.
Fig.4.ConceptualmodelbasedonfieldobservationsintheSaraille´ massifshowingtheevolutionofadistal,hotpassivemarginwithmantleexhumation.
5. Conclusion
TherecumbentfoldoftheSaraille´ massifshowsseveral featuresthatcanbeassociatedwiththedevelopmentof the Pyrenean paleomargin during Albian-Cenomanian extremecrustalthinning.DuctiledeformationinPalaeo- zoiccrustallenses,aswellasintheMesozoicsedimentary cover, is shown to have developed in relation to the detachments responsible for the mantle exhumation duringAlbian–Cenomaniantimes.Webringnewevidence thatextremecrustalthinningofthisdistalpassivemargin occurredinahotthermalenvironmentinrelationwiththe riseofthemantlealongadetachmentfault.Westressthe factthat,in suchconditions,ananastomosedpatternof numerouscrustallensesbuiltup,allowingtectoniccontact ofthepreriftsedimentarycoverwithmantlerocksinthe intervals between the crustal lenses. Zones of intense deformationwerelikelythepreferentialpathwaysforthe hotfluidsresponsibleforthetalc/chloritelayerminerali- zation.
Thiscontributionbringsimportantconstraintstoany modelofevolutionofdistalpassivemargins.IntheSaraille´
massif,the lower crustis surprisingly lacking and only lensesofuppercrustarerecognized.Thissuggeststhatthe lowercrustwasdecoupledfromtheuppercrustduringthe Albian–Cenomanianriftingandremainedatdepthinthe detachmentbetween the mantle and the crust (Teixell etal.,2016).Thelowercrustlikelyunderwentaboudinage intheearlystagesofcontinentalrifting,possiblydrivenby hydrationalongthemaincrustalextensionalshearzones, allowingtectonicsoftening.This providesconstraintsin reconstructingtherheological profileofthecrustbefore andduringtheAlbian–Cenomanianrifting.Addressingthis issuewillrequirefurther investigationsin similarPyre- neanmassifswheresubcontinentalmantleoutcropsarein contactwithcontinentalrocks.
Acknowledgments
Thisworkwasmadepossiblethroughagrant froma Master2,RGFproject(Re´fe´rentielGe´ologiquedelaFrance) ofthe ‘‘Bureau de RecherchesGe´ologiques et Minie`res’’
(BRGM,ThierryBaudin,manager).Thisarticlewasreviewed by Gianreto Manatschal and by MarcoScambelluri. Our manuscript greatly benefited from comments by both reviewers.We thankassociateeditor MargueriteGodard forconstructiveremarks.
References
Abzalov,M.Z.,1998.Chrome–spinelsingabbro–wehrliteintrusionsofthe Pechengaarea,KolaPeninsula,Russia:emphasisonalterationfeatu- res.Lithos43(3),109–134.
Albare`de,F.,Michard-Vitrac,A.,1978.Datationdume´tamorphismedes terrainssecondairesdesPyre´ne´espar lesme´thodes39Ar–40Aret
87Rb–87Sr ;ses relations avec lespe´ridotites associe´es.Bulletin.
Soc.Geol.France(5),681–687.
Blount,A.M.,Vassiliou,A.H.,1980.Themineralogyandoriginofthetalc depositsnearWinterboro.Alabama.Econ.Geol.75(1),107–116.
Boillot,G.,Agrinier,P.,Beslier,M.O.,Cornen,G.,Froitzheim,N.,Gardien,V., Girardeau,J.,Gil-Ibarguchi,J.I.,Kornprobst,J.,Moullade,M.,Scha¨rer, U.,Vanney,J.R.,1995.Alithosphericsyn-riftshearzoneattheocean- continenttransition:preliminaryresultsoftheGALINAUTEIIcruise (NautiledivesontheGaliciaBank,Spain).C.R.Acad.Sci.Paris,Ser.IIa 321,1171–1178.
Boulvais,P.,DeParseval,P.,D’Hulst,A.,Paris,P.,2006.Carbonatealter- ation associated with talc-chlorite mineralization in theeastern Pyrenees, with emphasis onthe St. BarthelemyMassif. Mineral.
Petrolog.88(3–4),499–526.
Boulvais,P.,Ruffet,G.,Cornichet,J.,Mermet,M.,2007.Cretaceousalbi- tizationanddequartzificationofHercynianperaluminousgranitein theSalvezinesMassif(FrenchPyre´ne´es).Lithos93(1),89–106.
Cane´rot,J.,Debroas,E.J.,1988.Remiseenquestiondu«Complexede rese´dimentationalbo-ce´nomaniendelazonenord-Pyre´ne´enne».C.R.
Acad.Sci.ParisSer.II307,1711–1716.
Cane´rot,J.,Peyberne`s,B.,Ciszak,R.,1978.Pre´senced’unemargeme´ri- dionalea` l’emplacementdelazonedesChaıˆnonsBe´arnais(Pyre´ne´es basco-be´arnaises).Bull.Soc.geol.France20(5),673–676.
Cane´rot,J.,Delavaux,F.,1986.Tectoniqueetse´dimentationsurlamarge nord-ibe´riquedeschaıˆnonsbe´arnais(Pyre´ne´es-be´arnaises).Remise enquestiondelasignificationdeslherzolitesdusommetdeSaraille´ C.
R.Acad.Sci.Paris,Ser.II302(15),951–956.
Caste´ras,M.,1970.OloronSainte-Marie,cartege´ologiquedelaFrance,1/
50000.BRGM,Orle´ans,France.
Choukroune,P.,1992.TectonicevolutionofthePyrenees.Ann.Rev.Earth Planet.Sci.20,143.
Choukroune,P.,Mattauer,M.,1978.Tectoniquedes plaquesetPyre´ne´es;sur lefonctionnementdelafailletransformantenord-pyre´ne´enne;compa- raisonsavecdesmode`lesactuels.Bull.Soc.geol.France5,689–700.
Clerc,C.,Lagabrielle,Y.,Neumaier,M.,Reynaud,J.Y.,deSaintBlanquat,M., 2012.Exhumationofsubcontinentalmantlerocks:evidencefrom ultramafic-bearingclasticdepositsnearbytheLherzperidotitebody, FrenchPyrenees.Bull.Soc.geol.France183(5),443–459.
Clerc,C.,Boulvais,P.,Lagabrielle,Y.,deSaintBlanquat,M.,2013.Ophi- calcitesfromthenorthernPyreneanBelt:afield,petrographicand stableisotopestudy.Int.J.EarthSci.1–23.
Clerc,C.,Lagabrielle,Y.,2014.Thermalcontrolonthemodesofcrustal thinningleadingtomantleexhumation:InsightsfromtheCretaceous Pyreneanhotpaleomargins.Tectonics33,1340–1359.
Clerc, C.,Lahfid,A.,Monie´, P., Lagabrielle,Y.,Chopin, C.,Poujol,M., Boulvais,P.,Ringenbach,J.-C.,Masini,E.,deStBlanquat,M.,2015.
High-temperaturemetamorphismduringextremethinningofthe continentalcrust:areappraisaloftheNorthPyreneanpassivepaleo- margin.SolidEarth6(2),643–668,http://dx.doi.org/10.5194/se-6- 643-2015.
Debroas,E.J.,Cane´rot,J.,Bilotte,M.,2010.LesBre`chesd’Urdach,te´moins del’exhumationdumanteaupyre´ne´endansunescarpementdefaille Vraconnien–Ce´nomanien infe´rieur (zone nord-pyre´ne´enne, Pyre´- ne´es-Atlantiques,France).Geol.Fr.2,53–63.
Due´e,G.,Lagabrielle,Y.,Coutelle,A.,Fortane´,A.,1984.Leslherzolites associe´esauxchaıˆnonsbe´arnais(Pyre´ne´esOccidentales):Misea`
l’affleurementante´-Doggeretrese´dimentationalbo-ce´nomanienne.
C.R.Acad.Sci.Paris,Ser.II299(17),1205–1210.
Fallourd,S.,Poujol,M.,Boulvais,P.,Paquette,J.L.,deSaintBlanquat,M., Re´my, P.,2014. Insitu LA-ICP-MSU-PbtitanitedatingofNa-Ca metasomatisminorogenicbelts:theNorthPyreneanexample.Int.
J.EarthSci.(Geol.Rundsch.)103,667–682.
Ferreira,N.,2013.Caracte´risationetconditionsdeformationdesserpen- tinespyre´ne´ennes(Master2),RapportM2R.Universite´ PaulSabatier, Toulouse,etGET,41p.
Fortane´,A.,Due´e,G.,Lagabrielle,Y.,Coutelle,A.,1986.Lherzolitesandthe western‘‘Chaıˆnonsbe´arnais’’(FrenchPyre´ne´es).Structuralandpa- leogeographicalpattern.Tectonophysics129(1),81–98.
Fortune´,J.-P.,1971.Contributiona` l’e´tudemine´ralogiqueetge´ne´tiquedes talcsPyre´ne´es(The`se).Universite´ PaulSabatier,Toulouse,454p.
Gaudichet,A.,1974.E´tudepe´trographiquedeslherzolitesdelare´gion d’OloronSteMarie(Pyre´ne´esatlantiques)(The`se).Universite´ Paris6, Paris,63p.
Golberg, J.-M., Leyreloup,A.F.,1990. High temperature-low pressure Cretaceousmetamorphismrelatedtocrustalthinning(EasternNorth PyreneanZone,France).Contrib.Mineral.Petrol.104(2),194–207.
Gong,Z.,Langereis,C.G.,Mullender,T.A.T.,2008.TherotationofIberia duringtheAptianandtheopeningoftheBayofBiscay.EarthPlanet.
Sci.Lett.273(1),80–93.
Huismans,R.,Beaumont,C.,2011.Depth-dependentextension,two-stage breakupandcratonicunderplatingatrifted margins.Nature 473 (7345),74–78.
James,V.,Cane´rot,J.,1999.Diapirismandpost-Triassicstructuraldevel- opmentofthewesternPyreneesandsouthernAquitaine.Eclogae Geol.Helv.92(1),63–72.
Jammes,S.,Manatschal,G.,Lavier,L.,Masini,E.,2009.Tectonosedimen- taryevolutionrelatedtoextremecrustalthinningaheadofapropa- gatingocean:exampleofthewesternPyrenees.Tectonics28(4). Jammes,S.,Manatschal,G.,Lavier,L.,2010.Interactionbetweenprerift
salt anddetachmentfaultinginhyperextended riftsystems:The
example oftheParentisand Maule´onbasins(Bay ofBiscayand westernPyrenees).AAPGBull.94(7),957–975.
Kaczmarek,M.A.,Mu¨ntener,O.,2010.Thevariabilityofperidotitecom- positionacrossamantleshearzone(Lanzomassif,Italy):interplayof melt focusingand deformation.Contributionsto mineralogyand petrology160(5),663–679.
Lagabrielle,Y.,Bodinier,J.L.,2008.Submarinereworkingofexhumed subcontinentalmantlerocks:fieldevidencefromtheLherzperido- tites,FrenchPyrenees.TerraNova20(1),11–21.
Lagabrielle,Y.,Labaume,P.,deSaintBlanquat,M.,2010.Mantleexhuma- tion,crustaldenudation,and gravitytectonicsduring Cretaceous riftinginthePyreneanrealm(SWEurope):Insightsfromthegeologi- calsettingofthelherzolitebodies.Tectonics29(4).
LeRoux,V.,Bodinier,J.L.,Tommasi,A.,Alard,O.,Dautria,J.M.,Vauchez,A., Riches,A.J.V.,2007.TheLherzspinellherzolite:refertilizedrather thanpristinemantle.EarthPlanet.Sci.Lett.259(3),599–612.
Masini,E.,Manatschal,G.,Tugend,J.,Mohn,G.,Flament,J.M.,2014.The tectono-sedimentaryevolutionofahyper-extendedriftbasin:the exampleoftheArzacq-Maule´onriftsystem(WesternPyrenees,SW France).Int.J.EarthSci.(Geol.Rundsch.)(submitted).
Mohn,G.,Karner,G.D.,Manatschal,G.,Johnson,C.A.,2015.Structuraland stratigraphicevolutionoftheIberia-Newfoundlandhyper-extended riftedmargin:aquantitativemodellingapproach.Geol.Soc.London, Spec.Publ.413,http://dx.doi.org/10.1144/SP413.9.
Moine,B.,Fortune´,J.-P.,Moreau,P.,Viguier,F.,1989.Comparativemin- eralogy,geochemistryandconditionsofformationoftwometaso- matictalcandchloritedeposits;Trimouns(Pyrenees,France)and Rabenwald(EasternAlps,Austria).Econ.Geol.84(5),1398–1416.
Mouthereau,F.,Filleaudeau,P.-Y.,Vacherat,A.,Pik,R.,Lacombe,O.,Fellin, M.G.,Castelltort,S.,Christophoul,F.,Masini,E.,2014.Placinglimitsto shorteningevolutioninthePyrenees:Roleofmarginarchitectureand implicationsfortheIberia/Europeconvergence.Tectonics33,2283–
2314,http://dx.doi.org/10.1002/2014TC003663.
Mun˜ oz,J.A.,1992.Evolutionofacontinentalcollisionbelt:ECORS-Pyre- neescrustalbalancedcross-section.In:McClay,K.R.(Ed.), Thrust Tectonics.ChapmanandHall,London,UK, pp.235–246.
Mu¨ntener, O., Piccardo, G.B., 2003. Melt migration in ophiolitic peridotites:themessagefromAlpine-Apennineperidotitesand
implicationsforembryonicoceanbasins.Geol.Soc.LondonSpec.
Publ.218,69–90.
Olivet,J.L.,1996.Lacine´matiquedelaplaqueibe´rique.Bull.Cent.Rech.
Explor.Prod.ElfAquitaine20(1),131–195.
Pe´ron-Pinvidic,G.,Manatschal,G.,2009.Thefinalriftingevolutionatdeep magma-poor passivemargins from Iberia-Newfoundland: a new pointofview.Int.J.EarthSci.98(7),1581–1597.
Poujol,M.,Boulvais,P.,Kosler,J.,2010.Regional-scaleCretaceousalbiti- zationinthePyrenees:evidencefrominsituU–Th–Pbdatingof monazite,titaniteandzircon.J.Geol.Soc.167(4),751–767.
Reston,T.J.,2007.Theformationofnon-volcanicriftedmarginsbythe progressiveextensionofthelithosphere:theexampleoftheWest Iberianmargin.Geol.Soc.London,Spec.Publ.282,77–110.
Roure,F.,Choukroune,P.,Bera´stegui,X.,Mun˜ oz,J.A.,Villien,P.,Matheron, P.,Bareyt,M.,Se´guret,M.,Camara,P.,De´ramond,J.,1989.ECORSDeep Seismicdataanddataandbalancedcross-sections:Geometriccons- traintsontheevolutionofthePyrenees.Tectonics8,41–50.
Scha¨rer,U.,De Parseval, D.,Polve´, M., deSaint Blanquat, M.,1999.
Formation ofthe Trimounstalc-chloritedeposit (Pyrenees)from persistenthydrothermalactivitybetween112and97Ma.TerraNova 11(1),30–37.
Sibuet,J.C.,Srivastava,S.P.,Spakman,W.,2004.Pyreneanorogenyand platekinematics.J.Geophys.Res.:SolidEarth(1978-2012)109(B8). Teixell,A.,Labaume,P.,Lagabrielle,Y.,2016.Thecrustalevolutionofthe west-centralPyreneesrevisited:inferencesfromanewkinematic scenario.C.R.Geoscience348,(thisissue).
Tugend,J.,Manatschal,G.,Kusnir,N.J.,Masini,E.,Mohn,G.,Thinon,I., 2014.Formation anddeformationofhyperextendedriftsystems:
InsightsfromriftdomainmappingintheBayofBiscay-Pyrenees.
Tectonics,AGUpublications.
Vauchez,A.,Clerc,C.,Bestani,L.,Lagabrielle,Y.,Chauvet,A.,Lahfid,A., Mainprice,D.,2013.PreorogenicexhumationoftheNorthPyrenean Aglymassif(EasternPyrenees-France).Tectonics32,1–12.
Verge´s,J.,Ferna`ndez,M.,Martı´nez,A.,2002.ThePyreneanorogen:pre-, syn-,andpost-collisionalevolution.In:Rosenbaum,G.,Lister,G.S.
(Eds.), Reconstructionoftheevolution oftheAlpine–Himalayan Orogen,8,JournaloftheVirtualExplorer,pp.57–76.
