Chronologie et signification des depots continentaux du Neogene superieur du bassin de Riez-Valensole (Alpes-de-Haute-Provence, France)

Dubar, Michel

doi:10.2113/gssgfbull.s7-xxvi.5.971

Cited by 16 publications

(22 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, the presence of deep Messinian canyons at Digne is compatible with the > 170 m incision (its base is not observable) of the Asse Messinian canyon [Dubar, 1984] in the Valensole-I conglomerates near Oraison ( fig. 1).…”

Section: Age Of the Paleo-canyonsmentioning

confidence: 60%

“…In most of the Valensole basin an unconformity is present at the top of the Valensole-I formation [Dubar, 1983[Dubar, , 1984: the Messinian erosional surface [Cita and Ryan, 1978] and its local deeply incised canyons [Barber, 1981;Clauzon, 1982]. In the Velodrome we can see that the basal Tanaron erosional surface has incised the conglomerates and most of the underlying marls forming the Valensole formation ( fig.…”

Section: Age Of the Digne Nappe Emplacementmentioning

confidence: 99%

“…In the northern part of the Valensole basin, like in the rest of the basin [Dubar, 1984], an erosional surface that postdates the Valensole-I conglomerates and predates the Zanclean canyons, is most probably the Messinian erosional surface. Consequently, the Tanaron formation is probably of Messinian to Early-Pliocene age.…”

Section: Age Of the Digne Nappe Emplacementmentioning

confidence: 99%

See 2 more Smart Citations

Messinian-Zanclean canyons in the Digne nappe (southwestern Alps): tectonic implications

Hippolyte

Clauzon

Suc

2011

Bulletin De La Société Géologique De France

View full text Add to dashboard Cite

Mapping thick conglomerates in the subalpine chains around Digne allows reconstruction of a deeply incised Messinian-Pliocene paleo-drainage network. It shows that the main rivers (Bléone, Bès, Mardaric, Eaux-Chaudes) have existed since at least the Messinian. Pollen analysis reveals that the Pliocene-Early Quaternary continental infill of these canyons did not start at 5.3 Ma, like in the Zanclean rias, but in the Late Pliocene (between 3.4 and 2.6 Ma). This 2 m.y. delay results in part from the timing of the retrogradation of the alluvial wedge, and in part from the inland shift of the river mouths that accompanied the Zanclean flooding of Messinian canyons. This shift corresponds to a shortening of hundreds of kilometers of the river profiles that caused the river to gain more erosive energy. This strong Zanclean erosion is contemporaneous with the main infill of the rias downstream.We describe sections of paleo-canyons that were uplifted, tilted, overthrusted or truncated by strike-slip faults. The geometry of this dissected drainage network provides new constraints on the tectonic evolution of the southern subAlpine chains. An about 2.3 km strike-slip separation of the Bléone river paleo-canyon confirms that the front of the Digne nappe is an oblique ramp of the south-verging thrust system of the 'Arc de Castellane'. This nappe moved south-southwestward along the N015 trending tear fault. Fault striation analysis in the Late Pliocene-Quaternary conglomerates shows that this displacement was characterized by ENE-WSW compression, along the Digne oblique ramp, consistent with its dextral slip. Most of the Digne nappe displacement (~20 km) occurred prior to the Late Pliocene as shown by the La Bonnette section of the Bléone paleo-canyon that incises a block of the overthrusted "residual basin". It was followed by~2.3 km southward displacement along out-of-sequence faults during the Late Pliocene and the Quaternary. This out-of-sequence reactivation of the Digne nappe is contemporaneous with the formation of the Barles half-window nappe anticline as shown by the 345 m uplift of the l'Escuichière paleo-canyon. The reconstructed paleo-drainage network attests for the tectonic activity of the Barles nappe anticline, the Bès tear fault, the Saint Benoît tear faults and the Digne nappe during the Pliocene and the Quaternary. Canyons messino-zancléens à remplissage continental dans la nappe de Digne (Alpes du Sud). Implications tectoniquesMots-clés. -Evénement messinien, Canyons messiniens, Réseau hydrographique, Tectonique quaternaire, Nappe de Digne, Barles.Résumé. -Dans les chaînes subalpines de Digne, la cartographie de conglomérats qui ont rempli de profonds canyons permet de reconstruire un réseau hydrographique attribuable au Messinien et au Pliocène. On met ainsi en évidence que les principales rivières (Bléone, Bès, Mardaric, Eaux-Chaudes) existent depuis au moins le Messinien. L'analyse de pollens provenant du fond de ces canyons révèle que leur remplissage Pliocène-Quaternaire n'a pas commencé à 5,3 Ma com...

show abstract

Section: Age Of the Paleo-canyonsmentioning

confidence: 60%

Section: Age Of the Digne Nappe Emplacementmentioning

confidence: 99%

Section: Age Of the Digne Nappe Emplacementmentioning

confidence: 99%

See 1 more Smart Citation

Messinian-Zanclean canyons in the Digne nappe (southwestern Alps): tectonic implications

Hippolyte

Clauzon

Suc

2011

Bulletin De La Société Géologique De France

View full text Add to dashboard Cite

show abstract

“…Sediments are Serravallian to Tortonian in age at the base (Clauzon et al, 1989), reaching the early Pleistocene (Mercier, 1979;Dubar et al, 1998). In detail two units separated by the Messinian erosional surface are distinguished in the conglomerates (Clauzon, 1979;Dubar, 1984a;Clauzon et al, 1989). A mapping of these units near the Asse river (Dubar, 1984a) shows that Pliocene conglomerates fill a Messinian canyon and form the top of the Valensole unit.…”

Section: Quaternary Folding In the Valensole Basinmentioning

confidence: 99%

Identification of Quaternary thrusts, folds and faults in a low seismicity area: examples in the Southern Alps (France)

Hippolyte

Dumont

2000

Terra Nova

View full text Add to dashboard Cite

In low seismicity areas, folds, faults and striated pebbles in recent alluvial deposits can demonstrate the Quaternary activity of tectonic structures and can reveal their kinematics. In the Digne nappe (Southern Alps), an out‐of‐sequence thrust occurred in the late Quaternary in response to WSW‐trending compression. The presence of late Quaternary compressional deformation in the Valavoire thrust could have resulted from the activity of the underlying Durance flexure with a maximum Pliocene–Quaternary uplift rate of about 0.1 mm yr−1. The Quaternary top surface of the Valensole basin, that truncates SW‐vergent thrust propagation folds, is folded above the Lambruissier anticline. Exceptional conditions resulted in the local preservation of this Quaternary fold morphology created with a minimum uplift‐rate of 0.05 mm yr−1 under a NE‐trending compression. At the front of the Digne nappe the deformation is characterized by WSW to WNW trends of compression and low strain rates during the Quaternary period.

show abstract

“…Clauzon et al, 1989). Deposition starts with Aquitanian marine sandstone, followed by the continental conglomerate of the Valensole Formation which is Serravallian to Tortonian in age at its base and up to the early Pleistocene at its top (Mercier, 1979;Clauzon et al, 1989;Dubar, 1984a;Dubar et al, 1998). The eastern edge of the basin is overthrusted by the Middle Miocene to Late Quaternary Digne Nappe (Lickorish and Ford, 1998;Roure et al, 1992;Gidon and Pairis, 1988;Hippolyte et al, 2011), and it is bordered to the West by the NNE-trending Durance seismic fault, a dextral fault 115 with a reverse west-side-up component (Roure et al, 1992;Cushing et al, 2008).…”

Section: Settingsmentioning

confidence: 99%

Hillslope denudation and morphologic response across a rock uplift gradient

Godard¹,

Hippolyte²,

Cushing³

et al. 2019

Preprint

View full text Add to dashboard Cite

Documenting the spatial variability of tectonic processes from topography is routinely undertaken through the analysis of river profiles, as a direct relationship between fluvial gradient and rock uplift has been identified by incision models.Similarly, theoretical formulations of hillslope profiles predict a strong dependence on uplift rates. However, the reduced sensitivity of near-threshold hillslopes and the limited availability of high resolution topographic data, has often been a major limitation for their use to investigate tectonic gradients. Here we combined high resolution analysis of hillslope morphology 5 and cosmogenic nuclides derived denudation rates to unravel the distribution of rock uplift across a blind thrust system at the Southwestern Alpine front in France. Our study is located in the Valensole Mio-Pliocene molassic basin, where a series of fold and thrust has deformed a plateau surface. We focused on a series of catchments aligned perpendicular to the main structures.Using a 1-m LiDAR Digital Terrain Model, we extracted hillslopes topographic properties such as hilltop curvature C HT or non-dimensional erosion rates E * . We observed a systematic variation of these metrics coincident with the location of a major 10 underlying thrust system identified by seismic surveys. Using a simple deformation model, the inversion of the E * pattern allows to propose a location and dip for a blind thrust, which are consistent with available geological and geophysical data.We also sampled clasts from eroding conglomerate at several hilltops locations for 10 Be and 26 Al concentration measurement.Calculated hilltops denudation rates range from 40 to 120 mm/ka. These denudation rates appear to be correlated with E * and C HT extracted from the morphological analysis, and are used to derive absolute estimates for the fault slip rate. This 15 high resolution hillslope analysis allows to resolve short wavelength variations in rock uplift, that would not be possible to unravel using commonly used channel profiles based methods. Our joint analysis of topography and geochronological data supports active thrusting at the Southwestern alpine front, and such approaches may bring crucial complementary constraints to morphotectonic analysis for slip rates on slow active faults.Similarly to river profiles, theoretical formulations of hillslope denudation predict a strong dependence of morphological parameters, such as slope or relief, on uplift rates. However, key elements of hillslope behavior such as the threshold stability angle for hillslope material and the non-linear relationship between sediment fluxes and topographic gradient (Roering et al., 1999(Roering et al., , 2001(Roering et al., , 2007, implies that for fixed valley spacing, hillslope morphology can be insensitive to changes in erosion or rock uplift rates over large range values (Burbank et al., 1996;Ouimet et al., 2009). This behavior is a major limitation for the use 50 of hillslope morphology to retrieve information about tectonic gradients. Furth...

show abstract

Chronologie et signification des depots continentaux du Neogene superieur du bassin de Riez-Valensole (Alpes-de-Haute-Provence, France)

Cited by 16 publications

References 0 publications

Messinian-Zanclean canyons in the Digne nappe (southwestern Alps): tectonic implications

Messinian-Zanclean canyons in the Digne nappe (southwestern Alps): tectonic implications

Identification of Quaternary thrusts, folds and faults in a low seismicity area: examples in the Southern Alps (France)

Hillslope denudation and morphologic response across a rock uplift gradient

Contact Info

Product

Resources

About