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The Pleistocene alluvial conglomerates of the Verdouble River valley, close to the famous Palaeolithic site of Tautavel, were the object of lithologic determinations including microtextural analysis intended to define their provenance, their sedimentary facies and their calcite cement.
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They testify to a rather late karst-induced excavation of the Gouleyrous Gorge and consequently to the relatively recent connection between the upstream and downstream basins of the Verdouble River. Lateral erosion by floods of the Verdouble probably destroyed ceoc Palaeolithic soils and settlements downstream of the Gouleyrous Gorges: Gary Fowler is acknowledged for checking the English and Thibaud Saos for technical help.
Thoughtful editings by D. Bridgland and two anonymous reviewers have improved the manuscript and are gratefully appreciated. Perched halfway up of a steep Urgonian limestone slope, this cave constituted a ideal observationary point from which to watch the movements of the herds of wild animals.
Facing southward and shielded from prevailing wind, this site is also situated near the water source of the Verdouble, a necessity for both man and animal. The deposits of the plain of Paziols and those of the Vingrau-Tautavel Depression will be described in succession fig.
Numbers 2a and 2b refer to following maps. In the upstream of Gouleyrous Gorge Paziols plain according to the geologic map of Rivesalte Berger et al.
Only the Pleistocene fluviatile deposits are exactly reproduced; the pebble accumulation inner delta fan in the upstream of Gouleyrous Gorge was added by the authors. River losses are indicated by arrows. In the downstream of Gouleyrous Gorge depression of Vingrau-Tautavel according to the geologic map of Tuchan Berger et al. Only the Pleiostocene fluviatile deposits are exactly reproduced. The location and nature of clastic sediment and the dating of its cements may provide constraints on the timing of calcrete formation and of aggradation and incision of the alluvial deposits.
These accumulations and their cements involve a combination of a rather warm and wet environment. The cements are thought to have developed during very early diagenesis allowing the consolidation and the preservation of the deposit. Fifteen new AMS dates from these cements will lead us to propose a Late Pleistocene geomorphic and processes history for the Verdouble Valley, and for the Tautavel region, that is slightly different from that of a widespread assumption that Verdouble alluvium are mid-Pleistocene or older ages Berger et al.
For absolute age dating of inorganic carbon, thin sections of the crystal fabrics and textures preserved provided the preliminary documentation. Therefore, various examples of the 14 C and Th dating of carbonate cements were provided through conglomerates of the proglacial valley fills of Austria Ostermann et al.
Various calcareous cement dates have also been undertaken for marine sediment, especially Holocene beach-rocks, and reconstituted sea level changes Ramsay and Cooper, ; Desruelles et al. Although the cement can be contaminated by carbonate particles other than the calcite cement, radiocarbon 14 C dating is still the most appropriate method for dating various Mediterranean beachrocks.
The bedrock is Silurian and Devonian in the north of the catchment, Jurassic for uplands bounding the catchment in the south and finally Jurassic and Cretaceous for the downstream course of the Verdouble and the Vingrau-Tautavel plain. The depth of karstification, several hundred metres below sea level, especially in the Opoul area and in Lower Agly, is mainly linked to: The second, downstream, leads up to the main Agly River: The origin of the pebbles of Fya mostly calcareous is the western part of the Verdouble catchment main course of the Verdoublewhereas the pebbles of Fyb mostly siliceous may come from the eastern part of the basin Donneuve and Tarassac tributaries.
Near Paziols, a cave-in allows observation of the subterranean flow of the Verdouble. This karst is an allogenic system, recharged by both precipitation and river water infiltration through swallow holes. These limestones are the sites of temporary emergences, but long-lasting springs remain rare. To the South of Paziols, a hot and sulphated spring indicates an inflow of deep water. The two main springs of this karst system emerge a few kilometers from each other.
Three historical floods during the last century are noteworthy and both involve the Tautavel-Vingrau Depression site.
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In period of low water level, the bed of the Verdouble River is generally dry at the confluence with the Agly River. On the map of Rivesaltes Berger et al. It is necessary to specify that peemis notion of terraces is used here only in reference of the geological maps of both Tuchan and Rivesaltes.
It does not involve the existence of a topographic shoulder on which deposits permie overlaid. Pebbles are cemented by several generations of sparites, sometimes partly dissolved and rubefied which testify to a long pedogenetic history.
These outcrops disappear downstream of Paziols and this level is unknown in the Tautavel-Vingrau Depression where some small residual hills Fx are mapped.
The pebbles are very heterometric and testify to the high flood discharges. Calcite cementation has allowed the fossilization of some deposits, pedmis accumulations of largely scattered pebbles are even more frequent.
Very curiously, of 36 inventoried deposits, only one is attributable to the Lower Palaeolithic fig. With dark grey colour, calcareous uplands and cliffs above the Depression. Broken line bounds the Upper Palaeolithic artefacts area. Site de la Teulera. The location and the good preservation of flint tools rule out an origin from a rock shelter deposit dismantled by erosion.
All the finds belong to the Mediterranean Acheulean of the Middle Pleistocene, in its ” Tautavelian ” facies Martzluff, Rare evidence concerns the end of the Old Palaeolithic and the Middle Palaeolithic periods, it has been well attested in the filling of the Caune de l’Arago by some Levalloisian artefacts.
These artefacts are composed of quartz or brown jaspers and, more rarely, in the case of two examples, they are significantly rolled as a result of transport. These extremely rare records are always associated with other more recent archaeological remains.
However, the particular location of these deposits is remarkable. Nearby, two other concentrations of artefacts can relate to the end of the Palaeolithic, but also to the Epipalaeolithic. On the other hand, downstream of this confluence, we found only a few scattered and much eroded artefacts of possible Palaeolithic affinity in the fluvial deposit, while all the catalogued archeological sites belong to the Neolithic or to Antiquity.
According to the current state of the knowledge, human occupation of a large sector of the valley situated downstream of the Gouleirous Gorge is restricted to the Holocene. In each case, the altitude values correspond to the sampling point. Several samples were the object of more precise determination in the laboratory microscope examination, determination of carbonate content and X ray diffraction.
The parts related to the upstream and the downstream of the Gouleyrous Gorges are separated by an empty line. These observations permitted the characterization of the nature of the constituents of the cements and allowed us to select samples on which dating could be carried out. It also allowed us to choose the optimal method for the extraction of the cement.
Fringes of cement were sampled with a microdrill under the microscope or simply selected by hand-picking lightly crushed materials for clean, unaltered calcite. Only some deposits protected by cementation can be dated, the others now being more or less scattered on the surface. This method allowed the analysis of only one hundred milligrams of carefully selected calcite spars.
Measurements were carried out at Poznan Radiocarbon Laboratory. Dating from snail shells Berger et al. They comprise deposits formed from poorly-sorted clasts of variable size and variable petrographic composition, weakly stratified, generally sub-rounded to angular cobble gravel with a consequent sand matrix.
Some mainly sandy accumulations show well-preserved oblique stratifications. The cement fringes consist of scalenohedral calcite spars and generally, a only one-step cementation is observed. Most cemented beds are not laterally continuous for more than a few tens of metres. The exposures are currently dry and inactive. The lithologic composition of the pebbles indicates a clear dominance of Cenozoic calcareous pebbles red, beige, grey or dark grey over siliceous pebbles from the Palaeozoic dark grey or black or from the Trias reddish sandstones; tab.
More or less rubefied rind cement forms a continuous, isopachous and single-layer coating on lithoclasts fig.
Moulin, the skeleton of the conglomerate results from a single sparitic border sp linking the gravels of sandstones s and schists scthe void volumes v remain very important. Moulin, the first micritic cement mi developed preferentially cfpc the surface of a calcareous clast at the top rather than on that of a siliceous clast at the bottomsparites sp attain a size from 1 to 2 mm.
Upward Permls station, one single phase deposition of sparitic cement sp linking various gravels, frequent voids v. Elongated cavity c between pemris calcareous lithoclasts clthe cavity is fringed by a single prmis rim sp A, D: Mesozoic calcareous pebbles are dominant over Palaeozoic siliceous pebbles and Trias sandstones tab.
Homogeneous sparitic cements of the conglomerate fig. The lithologic assemblage is very different perkis that of nearby Fya, because it is dominated by silicified or siliceous elements of which nearly a third is shale-like and presumed to be Ordovician. Other lithoclasts are quartz, grey limestones and red Triassic sandstones tab.
Lower still, the pebbles of the present streambed have a lithologic cecp close to that of Fyb, with a very strong dominance of dark or grey-brown, more or perkis schistose siliceous rocks, some Triassic sandstones, quartz with black siliceous veins and limestones tab.
The surfaces of several pebbles have traces of cement or coating that provide evidence of Fyb reworking. A little before the entrance of Gouleyrous, the banks of the Verdouble and the nearby surfaces are covered with abundant non-cemented pebbles.
It is a deeply incised gorge with nearly vertical Urgonian calcareous cliff. At the exit of this gorge, large erratic calcareous boulders of several meters diameter are observed near the foot of the cliff or at a few hundred metre distance farther indicating important collapses as a consequence of the nearby karstic erosion and probably of the recurrent earthquakes of the area Gilli et al.
It contains bluish and light grey calcareous pebbles of Urgonian age, with the rest of the assemblage consisting of siliceous pebbles ochre or brown Albian siltstones, beige Triassic sandstones, Ordovician schists that are very widely scattered in the nearby area tab.
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A seismic study allowed us to observe the accumulation of one metre of gravel brought by the great flood of and covering the lower accumulation Giresse et al. The lithologic composition of the pebbles of this recent flood pedmis that one of the lower accumulation. Some residual microcliffs of conglomerate testify to a cemented deposit Fxb on the map, fig.
At the Seille locality fig. More commonly, the dated isopachous fringes of calcite cement directly overlie lithoclasts. The remnant pore space above the cements is open. Calcareous pebbles are dominant over siliceous pebbles especially sandstones and dark schistswhich is a composition similar to that of the Fyb conglomerate, in the neighbourhood of Paziols tab.
Generally, an isopachous single-layer phreatic cement was observed, but in contrast to the conglomerate further upstream, we note locally some multi-layer phreatic cement.
In this last case, two distinct stages were noted: A dating of the undifferentiated addition of these two cements would thus have supplied only an apparent age. The first cementation, pigmented by ferric iron, is micritic mi and develops especially on the surface of calcareous pebbles, the second cementation is sparitic sp and respects some voids v edged by big palissadic crystals.
On a white calcareous lithoclast clpassage red arrow from a first pink micritic cement mi to a white sparitic cement sp. Higher magnification view of a sector of A showing the succession of a calcareous clast with a dark cover of oxides of manganese mthe first red cementation compounds of micrites and microsparites, the second white cementation consisting of sparites spthe last 0.
cec This 2 m-thick deposit is almost continuous for 50 m, but is cut locally by a reddish periglacial solifluction that packs angular fragments of Urgonian limestone.