jeanflop/post_ocr_correction2 huggingface dataset:
datations des rythmites glacio-lacustres de Llestui ont été présentées par Vilaplana [15], avec les résultats suivants : égaux ou plus anciens que 34 000 (Ly-3045), 31 500 (Ly-3046) et 33 000 ans BP (Ly-2942 et Ly-2943). D'après ces dates, deux hypothèses ont été formulées pour la chronologie du paléolac de Llestui : entre 65 000 et 31 500 ans BP [15] et entre 45 000 et 34 000 ans BP [6]. La présence de graphite dans les argiles de Llestui, provenant des ardoises graphiteuses du Silurien qui affleurent dans le bassin de ce paléolac, a cependant pu modifier l'âge de ces sédiments [19]. Pour le prouver, trois nouveaux échantillons ont été prélevés et analysés (fig. 2). Les datations obtenues avec une combustion des échantillons à 400°C sont les suivantes : Llestui A : 21 650±900 ans BP; avec δ13C: -20.42 °/oo (Gif-8778 bis). — Llestui B : Insuffisante quantité de gaz (Gif-8779 bis). CORRECTION ### SPOSITO, The chemistry of soils, Oxford University Press, Inc., 1985, 277 L'estimation C : 18 240 ±600 ans BP; avec δ13C: -21.68 °/oo (Gif-8780 bis). Par contre, l'âge des échantillons obtenus à partir d'une combustion du résidu à 900°C est plus ancien que 40 000 ans BP. Ces résultats nous indiquent le vieillissement, dû au graphite, des rythmites glacio-lacustres de Llestui. CONCLUSIONS. — Les nouvelles datations du complexe de Llestui nous permettent de dater ce paléolac entre 18 000 et 20 000 ans BP. Les âges qui avaient été proposés antérieurement [6], [7], [15] doivent être considérés comme trop anciens, à cause de la contamination des sédiments glacio-lacustres par du graphite silurien. La nouvelle chronologie du complexe de Llestui nous indique clairement que la dernière extension maximale glaciaire des Pyrénées est antérieure au Dernier Maximum Glaciaire Global. Pendant la période 18 000-20 000 ans BP, les glaciers pyrénéens avaient subi un important rétrait par rapport à leur extension durant la phase maximale régionale. La dynamique du glacier de Llauset, pendant la mise en place du paléolac juxtaglaciaire de Llestui, se caractérise par une réavancée. Cette récurrence glaciaire pourrait être interprétée comme une réponse locale dans
ans BP. Ces résultats nous indiquent le vieillissement, dû au graphite, des rythmites glacio-lacustres de Llestui. CONCLUSIONS. — Les nouvelles datations du complexe de Llestui nous permettent de dater ce paléolac entre 18 000 et 20 000 ans BP. Les âges qui avaient été proposés antérieurement [6], [7], [15] doivent être considérés comme trop anciens, à cause de la contamination des sédiments glacio-lacustres par du graphite silurien. La nouvelle chronologie du complexe de Llestui nous indique clairement que la dernière extension maximale glaciaire des Pyrénées est antérieure au Dernier Maximum Glaciaire Global. Pendant la période 18 000-20 000 ans BP, les glaciers pyrénéens avaient subi un important rétrait par rapport à leur extension durant la phase maximale régionale. La dynamique du glacier de Llauset, pendant la mise en place du paléolac juxtaglaciaire de Llestui, se caractérise par une réavancée. Cette récurrence glaciaire pourrait être interprétée comme une réponse locale dans les Pyrénées au refroidissement global qui a eu lieu pendant le Dernier Maximum Glaciaire. INTRODUCTION. — The maximum expansion of ice sheets in northern Europe during the last glacial cycle is established between 18,000 and 20,000 years before present (BP) [1], [2]. However, Seret et al. [3] demonstrated that in the French Vosges, at approximately 48°N, both the ice volume and extent were considerably larger between 50,000 and 30,000 years BP than during the Last Glacial Maximum. Thus, the glacial maximum may not have occurred at the same time around the world. According to Seret et al. [3] and Guiot et al. [4], the coldest phase was dry (700 mm less than modern values) and the maximum growth of the Vosges ice sheet occurred in an early phase of the last glacial cycle as a result of a large snow supply in a somewhat warmer climate. In the same way, the last glacial maximum in the Pyrenees, at a latitude between 42°43’N, is also previous to 18,000-20,000 years BP. In the southern Pyrenees, on the basis of available modern data arising from both regional geomorphological studies and detailed analysis of glacial and glaciolacustrine sequences, a glacial maximum and several deglaciation
the French Vosges, at approximately 48°N, both the ice volume and extent were considerably larger between 50,000 and 30,000 years BP than during the Last Glacial Maximum. Thus, the glacial maximum may not have occurred at the same time around the world. According to Seret et al. [3] and Guiot et al. [4], the coldest phase was dry (700 mm less than modern values) and the maximum growth of the Vosges ice sheet occurred in an early phase of the last glacial cycle as a result of a large snow supply in a somewhat warmer climate. In the same way, the last glacial maximum in the Pyrenees, at a latitude between 42°43’N, is also previous to 18,000-20,000 years BP. In the southern Pyrenees, on the basis of available modern data arising from both regional geomorphological studies and detailed analysis of glacial and glaciolacustrine sequences, a glacial maximum and several deglaciation phases being characterized by glacial pulsations have been defined [5] to [8]. The last glacial maximum in the northern Pyrenees is observed to have occurred before 38,400 years BP [9], [10]. Well before 20,000 years BP, Pyrenean glaciers had retreated upstream of the limits achieved during their phase of maximum development [11], [12] without any significant glacier readvance being recorded at around 20,000 years BP [10]. In this paper, new radiocarbon dates of glaciolacustrine rhythmites from the juxtaglacial complex of Llestui, a key locality for the last glacial cycle in the Pyrenees, will be presented and discussed. THE LLESTUI GLACIOLACUSTRINE COMPLEX. — Ice-marginal till complexes, mainly those in an ice-lateral (juxtaglacial) position in relation to the main valley glacier, are quite common in the Southern Pyrenees [13]. These complexes are related to a major phase of deposition that took place shortly after the last glacial maximum during the so-called Post-maximum stabilization phase [6] to [8]. Several ice-lateral till complexes have been recognized and studied in the Noguera Pallaresa, Noguera Ribagorçana, Esera and Ara basins [14] to [17], [6]. Ice-lateral till complexes were formed when the glacial tongues flowing down the main valleys blocked up the drainage of either ice-free or
development [11], [12] without any significant glacier readvance being recorded at around 20,000 years BP [10]. In this paper, new radiocarbon dates of glaciolacustrine rhythmites from the juxtaglacial complex of Llestui, a key locality for the last glacial cycle in the Pyrenees, will be presented and discussed. THE LLESTUI GLACIOLACUSTRINE COMPLEX. — Ice-marginal till complexes, mainly those in an ice-lateral (juxtaglacial) position in relation to the main valley glacier, are quite common in the Southern Pyrenees [13]. These complexes are related to a major phase of deposition that took place shortly after the last glacial maximum during the so-called Post-maximum stabilization phase [6] to [8]. Several ice-lateral till complexes have been recognized and studied in the Noguera Pallaresa, Noguera Ribagorçana, Esera and Ara basins [14] to [17], [6]. Ice-lateral till complexes were formed when the glacial tongues flowing down the main valleys blocked up the drainage of either ice-free or glacial tributary valleys. Thus, several sedimentary environments and their related deposits can be distinguished: glacial, glaciolacustrine, fluvio-torrential and slope deposits. All these formations are useful in order to reconstruct both the extension and the dynamics of Pleistocene glaciers. Moreover, they serve to define and characterize the different glacial phases within the Pyrenean deglaciation. One of the best examples of these complexes hitherto studied in the Pyrenees is the Llestui glaciolacustrine complex in the Llauset valley, a tributary of the Noguera Ribagorçana river (fig. 1). A glacial tongue about 10 kilometres long flowed through Llauset valley to join onto the main glacier in the Noguera Ribagorçana valley. The ice-lateral till complex of Llestui was formed on the left margin of Llauset glacier as a result of the drainage obstruction of two small fluviotorrential basins devoid of glaciers, giving way to the formation of a small juxtaglacial lake [14], [15]. Three sedimentary units have been distinguished in the Llestui complex [14], [15] (fig. 2) : — Glacial deposits: They are constituted by a lower subglacial till and an upper supraglacial till. These tills constitute the left lateral moraine of the Llauset glacier which blocked up the glaciolacustrine environment. Glaciolacustrine deposits: They are
the Pyrenean deglaciation. One of the best examples of these complexes hitherto studied in the Pyrenees is the Llestui glaciolacustrine complex in the Llauset valley, a tributary of the Noguera Ribagorçana river (fig. 1). A glacial tongue about 10 kilometres long flowed through Llauset valley to join onto the main glacier in the Noguera Ribagorçana valley. The ice-lateral till complex of Llestui was formed on the left margin of Llauset glacier as a result of the drainage obstruction of two small fluviotorrential basins devoid of glaciers, giving way to the formation of a small juxtaglacial lake [14], [15]. Three sedimentary units have been distinguished in the Llestui complex [14], [15] (fig. 2) : — Glacial deposits: They are constituted by a lower subglacial till and an upper supraglacial till. These tills constitute the left lateral moraine of the Llauset glacier which blocked up the glaciolacustrine environment. Glaciolacustrine deposits: They are mainly constituted by rhythmites consisting of millimetric to centimetric laminae of clays and sands, with common dropstones. However, gravels and diamictons are also interlayered in this unit. — Alluvial fan deposits: They consist of gravels and pebbles corresponding to two coalescent alluvial fans that were once functioning as a delta. These deposits cover the top of the glaciolacustrine unit and even lean on the lateral moraine. Vilaplana and Bordonau [18] and Bordonau [6] have described the sedimentary processes which can be recognized from the study of the glaciolacustrine sequence. CORRECTION ### L'estimation C : 18 240 ±600 ans BP; avec δ13C: -21.68 °/00 (Gif-8780 bis). Par contre, l'âge des échantillons obtenus à partir d'une combustion du résidu à 900°C est plus ancien que 40 000 ans BP. Ces résultats nous indiquent le vieillissement, dû au graphite, des rythmites glacio-lacustres de Llestui. CONCLUSIONS. — Les nouvelles datations du complexe de Llestui nous permettent de dater ce paléolac entre 18 000 et 20 000 ans BP. Les âges qui avaient été proposés antérieurement [6], [7], [15] doivent être considérés comme trop anciens, à cause de la contamination des sédiments glacio-lacustres par du graphite silurien. La nouvelle chronologie du complexe de Llestui nous
These deposits cover the top of the glaciolacustrine unit and even lean on the lateral moraine. Vilaplana and Bordonau [18] and Bordonau [6] have described the sedimentary processes which can be recognized from the study of the glaciolacustrine sequence. CORRECTION ### L'estimation C : 18 240 ±600 ans BP; avec δ13C: -21.68 °/00 (Gif-8780 bis). Par contre, l'âge des échantillons obtenus à partir d'une combustion du résidu à 900°C est plus ancien que 40 000 ans BP. Ces résultats nous indiquent le vieillissement, dû au graphite, des rythmites glacio-lacustres de Llestui. CONCLUSIONS. — Les nouvelles datations du complexe de Llestui nous permettent de dater ce paléolac entre 18 000 et 20 000 ans BP. Les âges qui avaient été proposés antérieurement [6], [7], [15] doivent être considérés comme trop anciens, à cause de la contamination des sédiments glacio-lacustres par du graphite silurien. La nouvelle chronologie du complexe de Llestui nous indique clairement que la dernière extension maximale glaciaire des Pyrénées est antérieure au Dernier Maximum Glaciaire Global. Pendant la période 18 000-20 000 ans BP, les glaciers pyrénéens avaient subi un important rétrait par rapport à leur extension durant la phase maximale régionale. La dynamique du glacier de Llauset, pendant la mise en place du paléolac juxtaglaciaire de Llestui, se caractérise par une réavancée. Cette récurrence glaciaire pourrait être interprétée comme une réponse locale dans les Pyrénées au refroidissement global qui a eu lieu pendant le Dernier Maximum Glaciaire. INTRODUCTION. — The maximum expansion of ice sheets in northern Europe during the last glacial cycle is established between 18,000 and 20,000 years before present (BP) [1], [2]. However, Seret et al. [3] demonstrated that in the French Vosges, at approximately 48°N, both the ice volume and extent were considerably larger between 50,000 and 30,000 years BP than during the Last Glacial Maximum. Thus, the glacial maximum may not have occurred at the same time around the world. According to Seret et al. [3] and Guiot et al. [4], the coldest phase was dry (700 mm less than modern values) and the maximum growth of the Vosges ice sheet occurred in
la mise en place du paléolac juxtaglaciaire de Llestui, se caractérise par une réavancée. Cette récurrence glaciaire pourrait être interprétée comme une réponse locale dans les Pyrénées au refroidissement global qui a eu lieu pendant le Dernier Maximum Glaciaire. INTRODUCTION. — The maximum expansion of ice sheets in northern Europe during the last glacial cycle is established between 18,000 and 20,000 years before present (BP) [1], [2]. However, Seret et al. [3] demonstrated that in the French Vosges, at approximately 48°N, both the ice volume and extent were considerably larger between 50,000 and 30,000 years BP than during the Last Glacial Maximum. Thus, the glacial maximum may not have occurred at the same time around the world. According to Seret et al. [3] and Guiot et al. [4], the coldest phase was dry (700 mm less than modern values) and the maximum growth of the Vosges ice sheet occurred in an early phase of the last glacial cycle as a result of a large snow supply in a somewhat warmer climate. In the same way, the last glacial maximum in the Pyrenees, at a latitude between 42°43’N, is also previous to 18,000-20,000 years BP. In the southern Pyrenees, on the basis of available modern data arising from both regional geomorphological studies and detailed analysis of glacial and glaciolacustrine sequences, a glacial maximum and several deglaciation phases being characterized by glacial pulsations have been defined [5] to [8]. The last glacial maximum in the northern Pyrenees is observed to have occurred before 38,400 years BP [9], [10]. Well before 20,000 years BP, Pyrenean glaciers had retreated upstream of the limits achieved during their phase of maximum development [11], [12] without any significant glacier readvance being recorded at around 20,000 years BP [10]. In this paper, new radiocarbon dates of glaciolacustrine rhythmites from the juxtaglacial complex of Llestui, a key locality for the last glacial cycle in the Pyrenees, will be presented and discussed. THE LLESTUI GLACIOLACUSTRINE COMPLEX. — Ice-marginal till complexes, mainly those in an ice-lateral (juxtaglacial) position in relation to the main valley glacier, are quite common in the Southern
basis of available modern data arising from both regional geomorphological studies and detailed analysis of glacial and glaciolacustrine sequences, a glacial maximum and several deglaciation phases being characterized by glacial pulsations have been defined [5] to [8]. The last glacial maximum in the northern Pyrenees is observed to have occurred before 38,400 years BP [9], [10]. Well before 20,000 years BP, Pyrenean glaciers had retreated upstream of the limits achieved during their phase of maximum development [11], [12] without any significant glacier readvance being recorded at around 20,000 years BP [10]. In this paper, new radiocarbon dates of glaciolacustrine rhythmites from the juxtaglacial complex of Llestui, a key locality for the last glacial cycle in the Pyrenees, will be presented and discussed. THE LLESTUI GLACIOLACUSTRINE COMPLEX. — Ice-marginal till complexes, mainly those in an ice-lateral (juxtaglacial) position in relation to the main valley glacier, are quite common in the Southern Pyrenees [13]. These complexes are related to a major phase of deposition that took place shortly after the last glacial maximum during the so-called Post-maximum stabilization phase [6] to [8]. Several ice-lateral till complexes have been recognized and studied in the Noguera Pallaresa, Noguera Ribagorçana, Esera and Ara basins [14] to [17], [6]. Ice-lateral till complexes were formed when the glacial tongues flowing down the main valleys blocked up the drainage of either ice-free or glacial tributary valleys. Thus, several sedimentary environments and their related deposits can be distinguished: glacial, glaciolacustrine, fluvio-torrential and slope deposits. All these formations are useful in order to reconstruct both the extension and the dynamics of Pleistocene glaciers. Moreover, they serve to define and characterize the different glacial phases within the Pyrenean deglaciation. One of the best examples of these complexes hitherto studied in the Pyrenees is the Llestui glaciolacustrine complex in the Llauset valley, a tributary of the Noguera Ribagorçana river (fig. 1). A glacial tongue about 10 kilometres long flowed through Llauset valley to join onto the main glacier in the Noguera Ribagorçana valley. The ice-lateral till complex of Llestui was formed on the left margin of Llauset glacier as a result of
to [17], [6]. Ice-lateral till complexes were formed when the glacial tongues flowing down the main valleys blocked up the drainage of either ice-free or glacial tributary valleys. Thus, several sedimentary environments and their related deposits can be distinguished: glacial, glaciolacustrine, fluvio-torrential and slope deposits. All these formations are useful in order to reconstruct both the extension and the dynamics of Pleistocene glaciers. Moreover, they serve to define and characterize the different glacial phases within the Pyrenean deglaciation. One of the best examples of these complexes hitherto studied in the Pyrenees is the Llestui glaciolacustrine complex in the Llauset valley, a tributary of the Noguera Ribagorçana river (fig. 1). A glacial tongue about 10 kilometres long flowed through Llauset valley to join onto the main glacier in the Noguera Ribagorçana valley. The ice-lateral till complex of Llestui was formed on the left margin of Llauset glacier as a result of the drainage obstruction of two small fluviotorrential basins devoid of glaciers, giving way to the formation of a small juxtaglacial lake [14], [15]. Three sedimentary units have been distinguished in the Llestui complex [14], [15] (fig. 2) : — Glacial deposits: They are constituted by a lower subglacial till and an upper supraglacial till. These tills constitute the left lateral moraine of the Llauset glacier which blocked up the glaciolacustrine environment. Glaciolacustrine deposits: They are mainly constituted by rhythmites consisting of millimetric to centimetric laminae of clays and sands, with common dropstones. However, gravels and diamictons are also interlayered in this unit. — Alluvial fan deposits: They consist of gravels and pebbles corresponding to two coalescent alluvial fans that were once functioning as a delta. These deposits cover the top of the glaciolacustrine unit and even lean on the lateral moraine. Vilaplana and Bordonau [18] and Bordonau [6] have described the sedimentary processes which can be recognized from the study of the glaciolacustrine sequence. The dominant processes responsible for the high rate of detritical sedimentation in paleolake Llestui were: — Processes related with instabilities (mass movements) in the subaerial or subaquatic slopes of the glaciolacustrine basin. — Processes related both
an upper supraglacial till. These tills constitute the left lateral moraine of the Llauset glacier which blocked up the glaciolacustrine environment. Glaciolacustrine deposits: They are mainly constituted by rhythmites consisting of millimetric to centimetric laminae of clays and sands, with common dropstones. However, gravels and diamictons are also interlayered in this unit. — Alluvial fan deposits: They consist of gravels and pebbles corresponding to two coalescent alluvial fans that were once functioning as a delta. These deposits cover the top of the glaciolacustrine unit and even lean on the lateral moraine. Vilaplana and Bordonau [18] and Bordonau [6] have described the sedimentary processes which can be recognized from the study of the glaciolacustrine sequence. The dominant processes responsible for the high rate of detritical sedimentation in paleolake Llestui were: — Processes related with instabilities (mass movements) in the subaerial or subaquatic slopes of the glaciolacustrine basin. — Processes related both with supraglacial and subglacial meltwater streams and mainly with inflowing streams coming from the two small tributary torrential basins. — Processes related with the seasonal existence of an ice-layer in the surface of lake Llestui. Fig. 2. — Geological cross-section of the glaciolacustrine complex of Llestui. Legend: 1. Alluvial-fan deposits; 2. Glaciolacustrine deposits; 3. Supraglacial till; 4. Subglacial till; 5. Paleozoic bedrock. Location of 14C samples in the glaciolacustrine unit. White dots correspond to radiocarbon dates presented by Vilaplana [15]: ≧ 34,000 yr BP (Ly-3045); ≧31,500 yr BP (Ly-3046); ≧33,000 yr BP (Ly-2942) and ≧ 33,000 yr BP (Ly-2943). Black dots correspond to radiocarbon dates presented in this paper: Llestui A, 21,650 ±900 yr BP (Gif-8778 bis); Llestui B, Not enough gas obtained (Gif-8779 bis) and Llestui C, 18,240 ±600 yr BP (Gif-8780 bis). Fig. 2. — Coupe géologique du complexe glacio-lacustre de Llestui. Légende: 1. Dépôts de cône de déjection; 2. Dépôts glacio-lacustres; 3. Till supra-glaciaire; 4. Till sous-glaciaire; 5. Substrat paléozoïque. Situation des échantillons datés dans l'unité glacio-lacustre. Les points blancs correspondent aux datations présentées par Vilaplana [15]: ≧ 34 000 ans BP (Ly-3045); ≧ 31 500 ans BP (Ly-3046); ≧ 33 000 ans BP (Ly-2942) et ≧