Sensibilité des milieux de montagne aux forçages climatiques et anthropiques depuis 14 000 ans ...

224 Pages·2014·29.52 MB·French

Doctorat Aix-Marseille Université
École doctorale 355 : Espaces, Cultures et Sociétés
Spécialité : Géographie Physique
Laboratoires CEREGE et IMBE

par
Elodie Brisset

Sensibilité des milieux de montagne aux
forçages climatiques et anthropiques
depuis 14 000 ans dans les Alpes du Sud

Approche multidisciplinaire (sédimentologie, géochimie, palynologie)
et multi-sites (lac Petit, lac de Vens et lac d’Allos)

- Volume II -
Soutenue le 6 mai 2014 devant le jury composé de
Jean-Nicolas Haas, professeur, Université de Innsbruck, rapporteur
Michel Magny, directeur de recherche, Université de Franche-Comté, rapporteur
Etienne Dambrine, professeur, Université de Savoie, examinateur
Laurent Lespez, professeur, Université Paris Est Créteil, examinateur
Nicolas Thouveny, professeur, Aix-Marseille Université, examinateur
Edward Anthony, professeur, Aix-Marseille Université, directeur de thèse
Frédéric Guiter, maître de conférences, Aix-Marseille Université, co-directeur de thèse
Cécile Miramont, maître de conférences, Aix-Marseille Université, co-directrice de thèse

Liste des annexes

Annexe 1 : Petersen et al., 2014. Article publié dans la revue Journal of Paleolimnology .................. 3

Annexe 2 : Wilhelm et al., 2012. Article publié dans la revue Quaternary Research ......................... 17

Annexe 3 : Parot et Renard, 2013. Mémoire de Master 1 Recherche ........................................................ 31

Annexe 4 : Photographies des sections du site de carottage VEN10 (Lac de Vens) ............................ 59

Annexe 5 : Poher, 2013. Mémoire de Master 2 Recherche ............................................................................ 63

Annexe 6 : Photographies des sections du site de carottage ALO11 (Lac d’Allos) ............................ 119

Annexe 7 : Poher et Tchong, 2012. Mémoire de Master 1 Recherche .................................................... 125

Annexe 8 : Troussier, 2013. Mémoire de Master 2 Recherche .................................................................. 153
Annexe 9 : Brisset et al., 2014. Article publié dans la revue CATENA .................................................... 203

1
2
Annexe 1 : Petersen et al., 2014. Article publié dans la
revue Journal of Paleolimnology

3
JPaleolimnol(2014)51:343–355
DOI10.1007/s10933-013-9759-x
ORIGINAL PAPER
Sediments of Lake Vens (SW European Alps, France)
record large-magnitude earthquake events
Jade Petersen • Bruno Wilhelm • Marie Revel • Yann Rolland •
Christian Crouzet • Fabien Arnaud • Elodie Brisset •
Eric Chaumillon • Olivier Magand
Received:18December2012/Accepted:5December2013/Publishedonline:20December2013
(cid:2)SpringerScience+BusinessMediaDordrecht2013
Abstract We studied sediment cores from Lake X-rayimages,grain-sizedistribution,majorelements
Vens (2,327 m asl), in the Tine´e Valley of the SW and magnetic properties shows the presence of six
Alps,totestthepaleoseismicarchivepotentialofthe homogenite-typedepositsinterbeddedinthesedimen-
lake sediments in this particularly earthquake-sensi- tarybackground.Thesesedimentologicalfeaturesare
tive area. The historical earthquake catalogue shows ascribed to sediment reworking and grain sorting
thatmoderatetostrongearthquakes,withintensitiesof causedbyearthquake-generatedseiches.Thepresence
IX–X,haveimpactedtheSouthernAlpsduringthelast ofmicrofaultsthatcross-cutthesedimentsupportsthe
millennium. Sedimentological (X-ray images, grain hypothesis of seismic deposits in this system. A
size distribution) and geochemical (major elements preliminarysedimentchronologyisprovidedby210Pb
and organic matter) analyses show that Lake Vens measurement and AMS 14C ages. According to the
sediments consist of a terrigenous, silty material chronology, the most recent homogenite events are
(minerals and organic matter) sourced from the attributable to damaging historic earthquakes in AD
watershed and diatom frustules. A combination of 1887 (Ligure) and 1564 (Roquebillie`re). Hence, the
Lake Vens sediment recorded large-magnitude
J.Petersen(cid:2)B.Wilhelm(cid:2)M.Revel(&)(cid:2)Y.Rolland E.Brisset
CNRS,IRD,ObservatoiredelaCoˆted’Azur,Ge´oazur UMR7263,IMBE,Technopoˆledel’Arbois,BP80,
UMR7329,NiceSophiaAntipolisUniversity, 13545Aix-en-Provencecedex04,France
250rueAlbertEinstein,SophiaAntipolis,
06560Valbonne,France E.Chaumillon
e-mail:[email protected] UMRCNRS7266LIENSs,Universite´ deLaRochelle,
2rueOlympedeGouges,17000LaRochelle,France
J.Petersen(cid:2)E.Brisset
CNRS,IRD,Colle`gedeFrance,UM34CEREGE, O.Magand
Aix-MarseilleUniversity,Technopoˆledel’Arbois, LGGE,LaboratoiredeGlaciologieetGe´ophysiquede
BP80,13545Aix-en-Provencecedex04,France l’Environnement,CNRS,UJF–Grenoble1,
38041Grenoble,France
C.Crouzet
CNRS,ISTerreUniversite´ deSavoie,Baˆtiment
Belledonne,73376LeBourgetduLac,France
F.Arnaud
LaboratoireEnvironnementDynamiqueetTerritoirede
Montagne,CNRS,Universite´ deSavoie,PoˆleMontagne,
73376LeBourgetduLac,France
123
344 JPaleolimnol(2014)51:343–355
earthquakes in the region and permits a preliminary paleoseismic documentation of major earthquake
estimate of recurrence time for such events of recurrenceduringtheHolocene.
*400 years.
Regionalseismichazardandvulnerability
Keywords Homogenites(cid:2)Paleo-earthquakes(cid:2)
Lakesediments(cid:2)Highaltitude(cid:2)SWEuropean The Alpes Maritimes is one of the most seismically
Alps activeregionsinthesouthwesternAlps,characterized
by historical Mw[6 and ongoing Mw\4 earth-
quakes(Courboulexetal.2003).Themostdamaging
Introduction known event was the AD 1564 Roquebillie`re earth-
quake, with an estimated maximum epicentre MSK
For several decades, lacustrine sediments have been intensity of IX–X (Boschi et al. 1997; Lambert and
recognizedasrecordersofearthquakesinseismically Levret1996;Laurenti1998).Suchstrongearthquakes
active areas (Seilacher 1969; Beck et al. 1996; are considered to have recurrence intervals of hun-
Chapron et al. 1999; Alfaro et al. 1999; Rodriguez- dreds to thousands of years (GEMEP 2005). These
Pascua etal.2000;Arnaud etal.2002;Strasseret al. seismogenichazardsproducehighriskbecauseofthe
2006; Wilhelm et al. 2013). Establishment of a denseurbanizationoftheMediterraneancoast.Previ-
detailed chronology of earthquakes in seismically ous mapping studies and monitoring of seismic
active areas is a critical objective to estimate the activity over 30 years identified many active faults
recurrence time of high-magnitude events. Earth- (Courboulexetal.2003;Sanchezetal.2010a,2010b;
quakes can be recorded in lacustrine sediments by Larroqueetal.2011;Bauveetal.2012).Vulnerability
different types of deposits, such as debris flows analysis,mainlyforthecityofNiceanditssurround-
(Arnaud et al. 2002; Nomade et al. 2005; Strasser ings, has been undertaken in recent years, and is
et al. 2006), turbidites (Shiki et al. 2000; Strasser already acknowledged by several organizations such
etal.2006),homogenites(Chapronetal.1999;Beck astheBRGM(BureaudesRecherchesGe´ologiqueset
2009) or deformation structures like liquefaction Minie`res),theIRSN(InstitutdeRadioprotectionetde
structures or microfaults (Beck et al. 1996; Monecke Suˆrete´ Nucle´aire) and the CETE (Centre d’E´tudes
et al. 2004). Whatever the form, formation and Techniques de l’E´quipement) for risk assessment.
preservation of earthquake records in lacustrine Monitoring of seismic activity, however, does not
sediments depends on several factors (Sims 1973, enable the estimation of recurrence time for large
1975):(1)thenatureofthesediment,mainlyitswater seismic events, which may be [1 ka. Hence, the
content and grain size (Plaziat and Ahmamou 1998; historic earthquake record is not long enough to
JewellandEttensohn2004;Moneckeetal.2004),(2) determine the frequency of large-magnitude events.
distance from the epicenter (Ambraseys 1988; Obe- Therefore,geologicalarchivessuchaslakesediments
rmeier 1996; Strasser et al. 2006) and (3) earthquake must be investigated to produce reliable seismic-
magnitude (Rodriguez-Pascua et al. 2000). hazardandrelatedriskassessments.
This paper presents results from a multi-proxy
studyofsedimentcoresfromLakeVens,locatedinan LakeVensgeologicalcontext
area subject to ongoing seismic activity, in the
southwestern Alps. The active Jausiers-Tine´e fault is Lake Vens (44(cid:3)18040N, 6(cid:3)55056E, 2,327 m asl) is
about2 kmNWofthelake,whichischaracterizedby locatedintheArgentera-Mercantourmassifalongthe
aswarmofmicroseismicity(Jenattonetal.2007)and Tine´e Valley (Alpes Maritimes, France), in the
Quaternary tectonic offsets of geomorphology (San- southwesternAlps(Fig. 1a).Thishigh-altitudemassif
chez et al. 2010a, 2010b; Darnault et al. 2012). The is composed mainly of Hercynian crystalline rocks
mainobjectiveofthisstudywastotestifhistorically (granite and gneiss), affected by strong localized
documented macro-seismic events were recorded by deformationsinnarrowfaultcorridors.Thisdeforma-
the Lake Vens sediments. If Lake Vens sediment tion is linked to the formation of the Alpine chain
provestorecordearthquakes,itwillbeausefultoolfor (Sanchez et al. 2011a, 2010b) and it is currently
123
JPaleolimnol(2014)51:343–355 345
A B
1
Bern
47° 2
Prealps Aar LGeopttohanrtdine 3
46° Geneva Aiguilles RoMtugBels. SL Insubric line 45
Belledonne Po basin Lake Vens (Fig. 2)
Grenoble Torino
45° Pelvoux
Genova
B Arg
South-East
basin
44°
Nice
Ligurian sea
6° 7° 8° 9° 10°
Fig.1 aSchematicgeologicalmapofthewesternAlps,with Apulian margin. (5) Molasse sediments deposited during the
locationofthestudyarea(benlargedontheleft).ExternalAlps Oligocene to Pliocene lie in the periphery of the Alps.
comprise:(1)Hercyniancrystallinebasement(crosses)andits b Simplified structural map of the northwest part of the
autochthonous Mesozoic sedimentary cover (white); (2) The Argentera-Mercantour massif (after Sanchez et al. 2010a, b,
transportedklippesofHelminthoidUpperCretaceousflyshand 2011a,b).TheredframeshowsthelocationofLakeVens,the
Internal Brianc¸onnais and Penninic units. Internal Alps com- mapofwhichisdisplayedinFig.2.Focalmechanismshighlight
prise:(3)Brianc¸onnaisandPiemontaiszones,whicharemadeof (1)theseismicswarmofthe2003–2004JausiersSeismiccrisis,
variablymetamorphosedrocksfromthecontinental European (2) earthquake of 26 February 2012 (Mw: 4.7) and (3)
marginandtheAlpineTethysoceanicdomain;(4)theAustro- earthquakeof1959(Mw:5.5)
Alpine units comprising the Dent Blanche klippe and the
gFeigo.m2orpahGoleoogliocgailcaland A VaMlloonnntet B N
characteristicsoftheLake N 2942 m a.s.l. 150 m
Venscatchment 500 m
(2,300masl)bBathymetric
mapofthelakeandlocation
oftheVEN09P3,VEN09P2 2500
andVEN10P2cores
0
2
B
004 Glacial 30
2 Lake Vens deposits
2327 m a.s.l. Scree 10
Sandstone & dolomite
Gneiss & migmatites
responsible for ongoing seismicity, especially in the Quaternarymorphologies(crestsandglacier-polished
Jausiers-Tine´e area (Jenatton et al. 2007; Sanchez surfaces)by5–50 m(Fig. 1b).
et al. 2010a, b) (Fig. 1b). One of main faults passes Thecatchment areaofLakeVensis4 km2andits
severalhundredmeterssouthofLakeVensandoffsets geology is composed mainly of gneiss, with only
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