French Maritime Alps Research Articles

Orobanche salviae (Orobanchaceae), new to the flora of the Iberian Peninsula

Orobanche salviae is a European orophyte and considered an exclusive parasite of Salvia glutinosa. Here we provide the first report of the species for the Iberian Peninsula, which we discovered recently in the eastern Catalan Pyrenees. The closest reliable known localities are in the French Maritime Alps, although it was also previously reported with uncertainty from the French Pyrenees. The new found populations are located at the absolute western limit of the distribution of the species. We provide a description of its distribution, habitat and, given its rarity, we suggest a category of threat following the IUCN criteria.

Larch as a Construction Material in Flemish Cabinetmaking of the Seventeenth Century: Dendrochronological Survey of a Larch Construction Panel of Flemish Metamorphoses Curio Cabinet RA 408 in the State Chateau Rájec nad Svitavou (Czech Republic)

ABSTRACT In the Rájec nad Svitavou chateau there is a Flemish cabinet from the period from about 1650–1680 decorated with scenes from Ovid's metamorphoses. The cabinet comes from the former collections of the house of Salm. The provenance is attributed to one of the suppliers of the Forchondt family art dealership. This cabinet was the subject of a conservation treatment in 2020. During this intervention, various surveys were completed. One of them was a dendrochronological survey of the larch construction panel found at the bottom of the cabinet. The presence of coniferous wood in the structure, together with the found inscription from 1845, called into question the authenticity of the cabinet. Dendrochronology proved that the larch panel was entirely contemporary and came from the French Maritime Alps. The last datable annual ring from an annual ring series of over 200 years was dated back to 1651. The cabinet case is certainly not the product of nineteenth century repairs in Prague. The result of dendrochronology is clear evidence of the use of imported softwoods in the manufacture of cabinets in Antwerp. The material was probably imported for the manufacturing of ships for the Dutch fleet, and the leftovers were sold on the local market. It can be assumed that more examples like this will appear in the future and should not be surprising.

Two new species of Protonemura Kempny, 1898 (Plecoptera: Nemouridae) from Southern France

Two new species of Protonemura Kempny, 1898, P. lupina sp. n., from the Castellane Prealps and the southern Mercantour region in the French Maritime Alps, and P. alexidis sp. n., from the southern flank of the Massif Central, are described, illustrated, and compared to their closest relative species P. risi (Jacobson Bianchi, 1905) and P. spinulosa (Navs, 1921). Information on distribution and ecological preferences of these new species is provided.

A Scotsman in Riviera: Thomas Allan and the geology of Nice (French Maritime Alps)

In the early nineteenth century, the Scottish geologist Thomas Allan (1777–1833) stayed for a period of vacation in Nice (Maritime Alps, SE France), the ‘capital’ of French Riviera. Allan had the occasion to run several excursion in the surroundings of the city, thus making numerous original observations about the geological setting of the region, which he reported in a paper published in 1818 in the Transactions of the Royal Society of Edinburgh. Making constant reference to the familiar rocks of Great Britain and Ireland, Allan described the stratigraphic succession of the Nice area in one of the earliest geological works on that region—and the first written in the English language. A colour geological sketch map, attached to the paper, represents the first published geological map of the region.

Cricotopus (s. str.) latellai sp. n., a new rheophilic species of the tremulus-group from the Italian and French Maritime Alps (Diptera: Chironomidae)

Cricotopus (Cricotopus) latellai sp. n. is described and diagnosed based on material comprising male and female pharate adults, pupal exuviae and larvae recently collected in some glacial streams in both the Italian and French Maritime Alps. Taxonomic notes provided in this paper include: description of C. latellai sp. n. as male and female adults, pupal exuviae and last instar larvae. The diagnosis of the Cricotopus tremulus-group is supplemented with additional characters in the male adult and pupal exuviae. Cricotopus latellai sp. n. keys near C. mantetanus Moubayed-Breil, 2016 and C. storozhenkoi Makarchenko & Makarchenko, 2016. Geographical distribution of C. latellai sp. n. is currently restricted to the Italian and French Maritime Alps. It belongs to the Tyrrhenian community of glacial relic species, which are considered to be indicators of climate change in this biogeographical region. Remarks, taxonomic position, and ecology of the new described species are given.

Geo-thermochronology of the Saint Antonin basin, south-eastern France

The clastic sedimentary formations of the Saint Antonin basin in the French Maritime Alps contain the record of the Early Oligocene erosional history of the Maures-Esterel massif, Sardinia and Corsica. Detrital apatite fission-track dating and zircon fission-track/U-Pb double dating of samples collected from the Saint Antonin basin confirm sediment provenance and allow obtaining first-order estimates of drainage basin maximum and long-term average exhumation rates. Whereas average exhumation rates were on the order of 0.1–0.2 km/Myr during the Early Oligocene, small parts of the Saint Antonin basin source areas may have experienced maximum exhumation rates on the order of 0.4–0.7 km/Myr. Although zircons and apatites with Early Oligocene fission-track cooling ages make up between 11–15% of the dated grains, a possible volcanic contribution is negligible, as only one single volcanic zircon grain was identified by fission-track/U-Pb double dating. Regional geodynamic processes with convergence in the Western Alps to the east and the end of the Pyreneo-Provençal compression phase by the early Oligocene controlled the differences in basin fill history and sediment provenance between the Saint Antonin basin and the largely contemporaneous Barrême basin in south-eastern France.

Annot Sandstone in the Peïra Cava basin: An example of an asymmetric facies distribution in a confined turbidite system (SE France)

High-resolution physical stratigraphy and detailed facies analysis have been carried out in the foredeep turbidites of Annot Sandstone in the Peïra Cava basin (French Maritime Alps) in order to characterize the relationship between facies and basin morphology. Detailed correlation patterns are evidence of a distinction between a southern bypass-dominated region, coincident with a channel-lobe transition and a north-eastern depositional zone, represented by sheet-like basin plain. These depositional elements are characterized by three main groups of beds related to the downcurrent evolution of bipartite flows. These facies groups are: 1) pebbly coarse-grained massive sandstones with rip-up mudstone clasts and impact mudstone breccias (Type I and II beds) deposited by basal dense flows, 2) coarse-grained massive sandstone overlain by tractive structures (Type III and IV beds) indicating the bypass of overlying turbulent flows and 3) massive medium-grained and fine-grained laminated sandstones related to the deposition of high and low density turbidity currents (Type V and VI beds). Ponding and reflection processes, affecting the upper turbulent flows, can characterize all type beds, but especially the beds of the third group. As described in other confined basins of the northern Apennines (Italy), the lateral and vertical distribution of these type of beds, together with other important sedimentary characteristics, - such as the sandstone/mudstone ratio, bed thicknesses, amalgamation surfaces and paleocurrents - reveal that the deposition of the Annot Sandstone in the Peïra Cava basin was controlled by an asymmetric basin with a steep western margin. This margin favored, on the one hand, basal dense flow decelerations and impacts, as well as bypass and deflection of the upper turbulent flows towards the north east.

The early geological exploration of the Nice region (French Maritime Alps) in the late 18th–19th centuries

At the southeastern termination of France, the Nice region during the late 18th–19th centuries represented one of the liveliest hearts of the geological ferment in Europe. The ‘capital’ of the French Riviera, this city attracted scores of renowned European naturalists including famous British geologists such as Thomas Allan, William Buckland, Henry Thomas De la Beche and Charles Lyell. Together with their local colleagues, these scientists contributed to shape the geological knowledge about this part of the Maritime Alps, and laid the foundations to the systematic and modern geological studies which have been carried out in this region starting from the second half of the 19th Century.

A Hanged From the Past: Medical Consideration on the Judas Iscariot Fresco-Chapelle Notre-Dame-des-Fontaines, La Brigue (15th Century).

The medieval chapel of Notre Dame-des-Fontaines (Our Lady of the Fountains), in the French Maritime Alps, is entirely covered by the fresco cycle of the Passion (15th century) that depicts the last days of Jesus from the Last Supper to the Resurrection. Under a small window, there is the brutal representation of the suicide of Judas Iscariot, hanging from a tree, with the abdomen quartered from which his soul, represented by a small man, is kidnapped by a devil. The author, Giovanni Canavesio, represented the traitor's death with very detailed anatomical structures, differently thus from other paintings of the same subject; it is therefore possible to assume that the artist had become familiar with the human anatomy. In particular, the realism of the hanged man's posture, neck bent in an unnatural way, allows us to hypothesize that it probably comes from direct observation of the executions of capital punishment, not infrequently imposed by the public authorities in low medieval Italy.

The Role of Microbial Activity In the Generation of Lower Cretaceous Mixed FE-Oxide-phosphate Ooids from the Provencal Domain, French Maritime Alps

Abstract Early Hauterivian mixed Fe-oxide–phosphate ooids from the Lower Cretaceous condensed succession of the Alpine Provencal Domain are ellipsoidal, 200–2000 µm in diameter, and the main component of a sedimentary body, 0–100 cm thick, that can be traced laterally for tens of kilometers. Cathodoluminescence, EDS microprobe, backscattered electron imaging, epifluorescence, XRD, and micro Raman spectroscopy reveal that ooid cortices consist of variable proportions of Fe-oxide-rich and Ca-phosphate-rich layers. SEM observations show that phosphate-rich layers are composed of a dense matrix of micrometer-size, rod-shaped, commonly curved phosphate grains, whose size and shape strongly suggest a microbial origin. Conversely, Fe-oxide-rich ooid cortical layers consist of aggregates of micrometer-size, plate-like crystals of hematite that point to an inorganic precipitation. We suggest that the ooidal condensed interval records a long sedimentary history in an open shelf environment subject to a background accumulation of organic-rich, fine-grained sediments. It was periodically interrupted by high-energy, storm-related events that resulted in winnowing, reworking, and oxygenation that favored precipitation of Fe-oxides around nuclei of biogenic origin. Such precipitation was not uniform on the outer surface of ooids and influenced their ellipsoidal shape. After the return to background conditions, Fe-ooids were buried and driven from an oxic to a post-oxic subbottom geochemical environment where rod-shaped Fe-reducing bacteria colonized Fe-ooid outer surfaces. Decomposition of organic matter and release of P bound on Fe-oxides increased pore-water concentration of phosphate, which precipitated at the outer surfaces of the ooids, thus preserving the microbial community. The bimineralic composition of these ooids discloses a complex and prolonged history of cyclic alternations of oxic and post-oxic geochemical conditions, which are in turn related to alternating sediment accumulation and winnowing phases with exposure at the seafloor.

Field expressions of the transformation of debris flows into turbidity currents, with examples from the Polish Carpathians and the French Maritime Alps

Various transformation mechanisms can generate turbidity currents from subaqueous debris flows. Different transformation mechanisms have been described and interpreted in the past from laboratory experiments and from deposits, but the two approaches have not generally been linked. This has made the genetic interpretation and comparison of deposits difficult. In this paper a generic classification scheme of debrite–turbidite couplets is proposed based on transformation mechanisms inferred from laboratory experiments. Five different flow types (called A–E herein) and their resulting deposits are detailed, but they are all part of a continuous spectrum, and a mixture of types is likely to be found in the field. Type A flows are strong, dense debris flows that undergo little transformation. Their deposit will be a debrite overlain by a thin turbidite, which is separated from it by a clear grain size break. Type B flows are weaker and can develop waves at the debris flow-turbidity current interface. The deposit will be a debrite with a wavy top overlain by a turbidite that is thicker than for type A flows. For type C flows, the interfacial waves will grow so much that the debris flow disintegrates into separate parts. The deposit will consist of debrite lenses encased in a turbidite. Type D flows will undergo even more mixing than type C flows so that the debrite parts will be mixed. Their deposit will be a turbidite with laterally varying areas of debrite characteristics near the bed. Type E flows will be so transformed that the debris flow character has disappeared and the flow is a turbidity current with high sediment concentration. The deposit will be largely turbiditic. The flow types and deposits will be illustrated with some examples from two field areas: the Polish Carpathians and the French Maritime Alps.

Extreme precipitation over the Maritime Alps and associated weather regimes simulated by a regional climate model: Present-day and future climate scenarios

We use the regional climate model RegCM nested within time-slice atmospheric general circulation model experiments to investigate the possible changes of intense and extreme precipitation over the French Maritime Alps in response to global climate change. This is a region with complex orography where heavy and/or extended precipitation episodes induced catastrophic floods during the last decades. Output from a 30-year simulation of present-day climate (1961–1990) is first analysed and compared with NCEP reanalysed 700 hPa geopotential heights (Z700) and daily precipitation observations from the Alpine Precipitation Climatology (1966–1999). Two simulations under forcing from the A2 and B2 IPCC emission scenarios for the period 2071–2100 are used to investigate projected changes in extreme precipitation for our region of interest. In general, the model overestimates the annual cycle of precipitation. The climate change projections show some increase of precipitation, mostly outside the warm period for the B2 scenario, and some increase in the variability of the annual precipitation totals for the A2 scenario. The model reproduces the main observed patterns of the spatial leading EOFs in the Z700 field over the Atlantic-European domain. The simulated large scale circulation (LSC) variability does not differ significantly from that of the reanalysis data provided the EOFs are computed on the same domain. Two similar clusters of LSC corresponding to heavy precipitation days were identified for both simulated and observed data and their patterns do not change significantly in the climate change scenarios. The analysis of frequency histograms of extreme indices shows that the control simulation systematically underestimates the observed heavy precipitation expressed as the 90th percentile of rainday amounts in all seasons except summer and better reproduces the greatest 5-day precipitation accumulation. The main hydrological changes projected for the Maritime Alps consist of an increase of most intense wet spell precipitation during winters for both scenarios and during autumn for the B2 scenario. Case studies of heavy precipitation events show that the RegCM is capable to reproduce the physical mechanisms responsible for heavy precipitation over our region of interest.

The Bouma Sequence (1962) and the resurgence of geological interest in the French Maritime Alps (1980s): the influence of the Grès d’Annot in developing ideas of turbidite systems

Abstract The two authors explain how and why the Grès d’Annot successions were chosen for their influential studies in the context of the 1960s and the 1980s. Arnold Bouma explains the origin of the Bouma Sequence in the 1960s, while Christian Ravenne focuses on the significance of the area as analogues of deep-sea fans and seismic stratigraphy in the 1980s. Ravenne recalls the main results obtained at that time: palaeogeographical maps, interpretative and synthetic sections, the spectacular onlap relationships at Chalufy, the strong interaction between seismic interpretation and field data, and the importance of large failures/collapses on the continental slope for the initiation of density surges.

Remembrance of things past: a hike along the Grès d’Annot research trail

Abstract This brief aperçu recalls some keynote studies on the Grés d’Annot in the French Maritime Alps that paved the way for my involvement with these rocks in the late 1950s. At that time, the topic of gravitative flows was gaining momentum, and various theories on underwater avalanches, including turbidity currents capable of carrying coarse sand to the deep sea, had already been proposed. However, these transport processes still needed considerable clarification. Discoveries, including the identification of the sandstones as turbidites by Faure-Muret and others in 1956, were not conceived in a vacuum, but rested on many years of previous research by numerous geologists. Some of the key earlier findings are cited here. My interests then, and for several decades afterward, were focused on the broader context of sedimentary petrology, downslope-to-deep marine deposition, palaeogeography and regional structural geology pertaining to these spectacular Tertiary sequences. Now that more than 40 years have passed, I look back and can better appreciate the role of others and their influence serving as a base for my modest effort. The ‘cutting of teeth’ experiences on the Grés d’Annot were truly fortunate, not only for my early formation as a sedimentologist, but also as I have continued to pursue related and progressively more diverse activities.

Contexte lithostructural, âges 40K40Ar et géochimie du volcanisme calco-alcalin tertiaire de Cap-d'Ail dans le tunnel ferroviaire de Monaco

Lithostratigraphic and structural framework, chronology and geochemistry of the Tertiary calc-alkaline volcanism of Cap-d'Ail (French Maritime Alps) are specified according to the new data collected during the earthworks of the recent railway tunnel built between Cap-d'Ail and Monaco. Two different magmatic events were dated: the first one, to Palaeogene, the other one, to Neogene. To cite this article: J.-P. Ivaldi et al., C. R. Geoscience 335 (2003).

Model for turbidite-to-contourite continuum and multiple process transport in deep marine settings: examples in the rock record

Petrological analysis of geological sections in St. Croix in the Caribbean, the Niesenflysch in Switzerland and the Annot Sandstone in the French Maritime Alps sheds light on multiple process transport in deep marine settings. A model depicting a turbidite-to-contourite continuum of stratal types is applied to these three rock units. Recognition of a diverse suite of bedforms, coupled with analysis of paleocurrents, helps to better interpret depositional origin and basin paleogeography. The St. Croix strata record emplacement by gravity flows and, subsequently, by bottom currents flowing parallel to the base of slope; these sediments accumulated on a lower slope apron. A Niesenflysch section in the Swiss Alps west of Adelboden includes turbidites which were deposited at fairly regular intervals beyond the base of slope, in a setting more distal than that of the St. Croix sequences. Most of these turbidites appear to have been partially reworked by bottom currents related to basin circulation or to density flows from the basin margins. In the Annot Sandstone, reworked turbidites (termed transitional variants) and packets of entirely rippled strata are observed in submarine fan and slope sequences in the Peira-Cava area. In contrast to those in St. Croix and the Niesenflysch, the current-emplaced deposits of the Annot Sandstone are directly associated with fan-valley deposits. Such rippled strata in channels are deposits of gravity flow origin which were subsequently reworked downslope by currents generated by successive gravity flows; they also occur on levees by overbank flow. Consideration of multiple process transport is of special help to interpret sections which are poorly exposed, or which can be examined in cores, or which are located in sequences that have been highly deformed structurally.

Migratory and Braided Channels in Eocene Submarine Fan Deposits in the French Maritime Alps: ABSTRACT

Migratory and Braided Channels in Eocene Submarine Fan Deposits in the French Maritime Alps: ABSTRACT

Passive rotation of hematite during deformation: a comparison of simulated and natural redbeds fabrics

A simulation model is used to generate pole figures assuming strain-induced passive rotation of hematite crystals. Comparison of simulated and natural hematite fabrics allows us to distinguish between dominant passive rotation and other grain-scale deformation mechanisms. Two natural examples are discussed: redbeds from the French Maritime Alps and Pyrenean redbeds. Fabrics indicate that passive rotation is the dominant reorientation mechanism of primary hematite grains during progressive deformation of redbeds.

Welded Slump-Graded Sand Couplets: Evidence for Slide-Generated Turbidity Currents (Gres D'Annot Submarine Fans, Maritime Alps): ABSTRACT

Most investigations that discuss the origin of turbidites state, or intimate, that turbidity currents are surges commonly initiated by catastrophic events related to submarine sliding on slopes. This concept is almost universally accepted by specialists although little hard observational data are available. In general theory, failure is triggered by stresses that can result from several factors (high sediment accumulation rate, slope oversteepening, earthquake, subsurface gas generation, etc) which give rise to excess pore pressure and a weakening of the sediment. Liquefaction and decrease in overall shear resistance are usually invoked as causes of sediment mobility. Increased mobility within the slab results in increased disorder of original sediment stratification an structure. Grain-to-grain structure is disrupted during acceleration, causing changes in pore pressure and allowing mixing with water that, in turn, results in further alteration of original structure. Metastable, high sensitivity, cohesionless sediments are most susceptible to mobility and, in turn, transformation from submarine sliding to turbidity current flow. Continuing sedimentologic studies of spectacularly exposed gres d'Annot deep-sea fan deposits (lowermost Oligocene) in the French Maritime Alps provide clues to resolve the problem of slide-to-turbidite transformation. Most noteworthy are massive channelized strata in upper and mid-fan sectors characterized by a lower slump member that evolves upward to a turbidite. This merging is indicative of probable generation of sediment gravity flows from submarine sliding. A proposed scheme suggests failure on a fan valley wall by submarine sliding that could entrain the flow of sand either from adjacent reaches of valley walls and/or from farther up-axis in the fan valley. In this manner, flow of some of the sand initiated by the sliding event would come to rest at nearly the same time and po ition as the slump mass near the base of the fan valley wall and in the axis proper. In some cases, the slump mass may bypass the base of the valley wall and, as it accelerates, transformation may be induced with resulting flow of sediment down-axis and basinward. The above phenomenon has a bearing on hydrocarbon exploration. Modern ocean floor surveys and regional field studies, such as those of the Annot Sandstone Formation, indicate that there is a nonrandom distribution of turbidites with respect to slumps deposited on marine margins and basins. Moreover, massive channelized submarine fan valleys may serve as ideal reservoirs for both oil and gas. Thus the model proposed here, if valid, clearly would be important in helping refine paleogeographic interpretation and in pinpointing potential hydrocarbon-bearing targets in the subsurface. End_of_Article - Last_Page 799------------

Comparing patterns of sedimentation in some modern and ancient submarine canyons

In this study, an attempt is made to compare probable submarine canyon deposits of Tertiary age well exposed in the French Maritime Alps with the Pleistocene-Holocene sediment fill of the Gully submarine canyon on the continental margin off Nova Scotia, Canada. Similarities in geometry, stratification, texture, and assemblages of sedimentary structures in these fossil and modern deposits are remarkable. A comparison of modern and fossil analogs provides marine geologists with an additional tool for better interpreting the mechanism of sediment dispersal in modern canyons which remain logistically difficult to study, and enables stratigraphers to recognize submarine valley deposits preserved in the fossil record.