Lakes are threatened by contemporary climate change and human activities. Paleohydrological records provide important evidence for developing scenarios for future changes in the availability of freshwater resources. This study presents a synthesis of a sedimentological, archeological, and chronological dataset collected from Lake Annecy (eastern France) to reconstruct a lake-level record documenting the whole Holocene. This dataset shows a pronounced minimum in the lake level during the Holocene thermal maximum (HTM) (ca. 9000–7000 cal BP), preceded by a general lowering trend (early Holocene), and followed by a general rising trend (Neoglacial). On both the millennial and centennial scales, the Lake Annecy record appears to match the regional pattern of Holocene lake-level fluctuations established for West-Central Europe. In agreement with other extra-regional paleoclimatic records, it shows the dominant influence of orbital forcing. The high magnitude of the lake-level lowering (more than 5 m) during the HTM, with a 2–2.5 °C difference between the HTM and the pre-industrial mean summer temperatures, suggests possible drastic lake-level lowering phases in the near future depending on the IPCC scenarios following climate change. This would mean dramatic impacts on human activities and the preservation of exceptional archeological remains in regional lake basins.

The composition of bioactive polyphenols from grape canes, an important viticultural byproduct, was shown to be varietal-dependent; however, the influence of soil-related terroir factors remains unexplored. Using spatial metabolomics and correlation-based networks, we investigated how continuous changes in soil features and topography may impact the polyphenol composition in grape canes. Soil properties, topography, and grape cane extracts were analyzed at georeferenced points over 3 consecutive years, followed by UPLC-DAD-MS-based metabolomic analysis targeting 42 metabolites. Principal component analyses on intra-vintage metabolomic data presented a good reproducibility in relation to geographic coordinates. A correlation-driven approach was used to explore the combined influence of soil and topographic variables on metabolomic responses. As a result, a metabolic cluster including flavonoids was correlated with elevation and curvature. Spatial metabolomics driven by correlation-based networks represents a powerful approach to spatialize field-omics data and may serve as new field-phenotyping tool in precision agriculture.

A set of sedimentological, archaeological and chronological data from littoral sites of Lake Annecy (Savoie, France) is used to reconstruct a Holocene lake-level record. It combines studies (i) of sediment sequences observed on the northern shore and (ii) of sediment cores from littoral mires and plateform on (or close to) archaeological sites of the western shore. On a multimillennial scale, the results give evidence of three major phases characterized by a general trend to lowering until ca 9000 cal BP, a lowest lake-level until ca 7000 cal BP and a general trend to rise until the present. It also gives evidence of multicentennial fluctuations superimposed on the plurimillennial phases. Taken together, the Lake Annecy record shows a pattern of lake-level changes similar to the regional one reconstructed for west-central Europe. In agreement with other Alpine and extra-regional palaeoclimatic records, it supports the hypothesis of different climate forcing factors with (i) a dominating impact of orbitally driven summer insolation, (ii) an influence of deglacial outbursts in the North Atlantic Ocean, and (iii) a possible impact of variations in solar activity.

Un corpus de données sédimentologiques, archéologiques et chronologiques collectées sur des sites au bord du lac d'Annecy (Haute‑Savoie, France) est utilisé pour reconstruire les variations du plan d'eau au cours de l'Holocène. Il combine l'étude de séquences sédimentaires reconnues sur la rive nord du lac et celle de carottes sédimentaires extraites sur ou à proximité de sites archéologiques localisés dans les marais littoraux ou sur la plateforme littorale de la rive ouest du lac. À une échelle plurimillénaire, les résultats font apparaître trois phases majeures caractérisées, la première par une tendance à la baisse au cours de l'Holocène ancien jusque vers 9000 cal BP, la seconde par une succession d'étiages prononcés du plan d'eau jusque vers 7000 cal BP, et la troisième par une tendance générale à la hausse jusqu'à l'actuel. Surimposées sur ces phases plurimillénaires, sont également mises en évidence des fluctuations d'ordre pluriséculaire du niveau du lac. L'ensemble s'inscrit dans le schéma régional des variations holocènes du niveau des lacs établi pour le centre‑ouest de l'Europe. En accord avec d'autres enregistrements paléoclimatiques régionaux et extra‑régionaux, il conforte encore l'hypothèse de différents forçages climatiques avec une influence dominante des variations orbitales de l'insolation ainsi que l'impact des épisodes successifs de vidange des grands lacs proglaciaires qui ont ponctué la déglaciation dans l'Atlantique Nord, et celui possible des variations de l'activité solaire. A set of sedimentological, archaeological and chronological data from littoral sites of Lake Annecy (Savoie, France) is used to reconstruct a Holocene lake‑level record. It combines studies (i) of sediment sequences observed on the northern shore and (ii) of sediment cores from littoral mires and plateform on (or close to) archaeological sites of the western shore. On a multimillennial scale, the results give evidence of three major phases characterized by a general trend to lowering until ca 9000 cal BP, a lowest lake‑level until ca 7000 cal BP and a general trend to rise until the present. It also gives evidence of multicentennial fluctuations superimposed on the plurimillennial phases. Taken together, the Lake Annecy record shows a pattern of lake‑level changes similar to the regional one reconstructed for west‑central Europe. In agreement with other Alpine and extra‑regional palaeoclimatic records, it supports the hypothesis of different climate forcing factors with (i) a dominating impact of orbitally driven summer insolation, (ii) an influence of deglacial outbursts in the North Atlantic Ocean, and (iii) a possible impact of variations in solar activity.

La Reserve Naturelle Regionale Geologique (RNRG) de Pontlevoy inauguree en 2018 comprend deux anciennes carrieres (carriere du Four a Chaux et carriere du Haut de la Plaine Saint-Gilles). On peut y observer en superposition stratigraphique les principales formations miocenes du secteur situe entre Loire et Cher au sud de Blois : Calcaire de Beauce de l’Aquitanien, Sables et marnes du Blesois du Burdigalien et Faluns du Blesois du Langhien, les deux dernieres etant fossiliferes. Apres une breve synthese sur les formations miocenes de la region, sont presentees ici des donnees sedimentologiques sur les formations visibles dans la RNRG et les resultats de nouvelles fouilles paleontologiques dans les Sables et marnes du Blesois de la reserve. La prospection geophysique par conductivite electrique, ainsi que les sondages et forages carottes effectues entre les deux carrieres avant l’amenagement de la reserve, ont revele (1) la presence d’une nouvelle formation fluviatile comblant un profond chenal incise dans le falun langhien ; cette formation peut etre rapportee au Serravallien ou au Miocene superieur et (2) la presence d’une faille a regard est et decrochement senestre affectant l’ensemble des formations miocenes.

Accumulation of organic matter in fens of fluvial valleys is often related to a low terrigenous matter delivery and to palaeoenvironmental conditions inducing low mechanical erosion. These assumptions come from the interpretation of contents in organic (MO) and mineral (MM) matters in sediments, expressed in percents, and then exactly anticorrelated. Calculation of mass accumulation rates of MO ( T aMO ) and MM ( T aMM ), expressed in g m − 2 yr − 1 , shows that T aMO and T aMM generally are not anticorrelated and that high values of T aMO and T aMM could appear simultaneously.

A new high-resolution bathymetric map combined with a regional Digital Elevation Model (DEM) analysis reveal the modalities of occurrence and emplacement of post-spreading magmatism along the NNE-SSW oriented, 1000 km long Tore-Madeira Rise (TMR) as well as its relationship with the activity of major fault systems including the Estremadura Fault System (ESF) and the Azores-Gibraltar Fracture Zone (AGFZ). Morphological and structural analysis of the bathymetric map were performed to map volcanic features such as eruptive cones, vents and fissures together with faults along the TMR. The new bathymetric map shows that the main NNW-SSE seamount alignment is formed by three structurally distinct volcanic massifs, the Tore, the Josephine and the Southern Volcanic Groups. The majority of the volcanoes of each group emplaced within or along specific portion of pre-existing faults (ESF and AGFZ) including splay fault, releasing bend, fault tips and interaction zones between different segments. Magmas were channelled into sub-vertical pre-existing lithospheric faults that acted as preferential pathways for the vertical magma ascent. Migration and final eruption of magma are controlled by the local stress variation induced by complex fault geometries, change in plate kinematics as well as strong shear zone anisotropy as suggested by the emplacement within localised areas of transtension. We conclude that post-spreading magma emplacement in the southern part of the Iberia margin was related to the development of a transtensional plate boundary between the Iberian and African Plate during the Late Cretaceous. More generally, our findings emphasize that the distribution of volcanism as the expression of the interaction between shallow plate tectonic and mantle processes should be included in plate kinematic reconstruction. This study also demonstrates that the accurate mapping of oceanic seafloor is pivotal to better understand tectono-magmatic evolution of volcanic seamount chains and geological processes in oceanic domains.

To best utilize the electrical'resistivity data and slope intensity derived from a Digital Elevation Model, the kriging spatial components technique was applied to separate the nuggets and small- and large-scale structures for both resistivity and slope intensity data. The spatial structures in the resistivity and slope intensity data, which are poorly correlated with soil thickness (ST), are then filtered out prior to integrating the resistivity data and slope intensity into soil thickness estimation over a 12 ha area located in the south-western Parisian Basin (France). ST was measured at 650 locations over the study area by manual augering. Twenty percent of the observations (131 points) were randomly selected to constitute the validation dataset The remaining 80% of the dataset (519 points) was used as the prediction dataset The resistivity data represent a set of 7394 measurement points for each of the three investigated depths over the study area. The methodology involves successively (1) a principal component analysis (PCA) on the electrical measurements and (2) a geostatistical filtering of the small-scale component and noise in the first component (PC1) of the PCA. The results show that the correlation between ST and PC1 is greatly improved when the small-scale component and noise are filtered out, and similarly, the correlation between ST and slope intensity is greatly improved once the geostatistical filtering is carried out on the slope data. Thus, the large scales of both slope intensity and the electrical resistivity's PC1 were used as external drifts to predict ST over the entire study area. This prediction was compared with ordinary kriging and kriging either with a large scale of slope intensity or with a large scale of the electrical resistivity's PC1 taken as an external drift. The first prediction of ST by ordinary kriging, which was considered as our reference, was also compared to those achieved by kriging using the raw secondary variables: PC1 and slope intensity as external drifts; slope intensity as an external drift; and PC1 as an external drift. The results indicate a reasonably low bias of prediction for all of the methods, in particular in the case of kriging using the large scales of both slope intensity and PC1 as external drifts. The root mean square error shows that kriging accounting for the large scales of two secondary exhaustive variables is the most accurate prediction method. The relative improvement of the accuracy is at least equal to 29% between the approach accounting for both large scale components of secondary attributes in the spatial estimates of ST and the other approaches of estimates considered in this study. (C) 2017 Elsevier B.V. All rights reserved.

Ce travail examine : (i) comment les correlations spatiales entre une variable du sol et les attributs topographiques peuvent etre ameliorees en mettant l'accent sur les relations entre ces deux types d'information a des echelles spatiales specifiques ; (ii) l'effet des sources des attributs topographiques utilisees comme variables explicatives pour la modelisation de la variable consideree ; (iii) la possibilite de l'extrapolation du modele pour la cartographie au-dela de la zone ou il a ete etabli.

This paper investigates how the spatial correlations between topographic attributes and a soil thickness can be improved by focusing on the relationships between them at specific spatial scales. In addition, this paper examines the effects of the topographic attribute data sources that are used as explanatory variables for modeling the response variable, and considers the possibility of model extrapolation for mapping beyond the area where the model was established. Here, factorial kriging analysis (FKA) and partial least square regression (PLSR) analysis are used to separate nuggets and small- and large-scale structures in data including four topographic attributes and soil thickness (ST). These analyses were conducted at different scales to analyze the relationships between ST and the selected topographic attributes in the southwest region of the Parisian Basin. The structural correlation coefficients from the FKA show strong correlations between the variables. These correlations, which change as a function of spatial scale, are not revealed by the linear correlation coefficients. The Eigen vectors from the principal component analysis that was performed on the small-scale and large-scale structures of the linear co-regionalization model are used to obtain ST and the topographic attributes at both spatial scales over the study area. The ST models are built as a function of topographic attributes using PLSR. Results have shown that the models built using variables that were assessed at a specific scale are better at predicting the target variable than models that were built using raw data. Regarding the models that were built using raw data, the structural correlations that occur at different spatial scales are merged together and the variance–covariance matrix of the nugget that represents data noise is not filtered out. Measures of model performance that are based on a validation data set have shown that the model based on small-scale structure (Model-S) is better for predicting soil thickness than the model based on large-scale structure (Model-L). The effects of topographic attribute data sources as explanatory variables for modeling ST are less significant than the effects of the two models for mapping. Moreover, extrapolation of the model-S beyond the area where it was generated is appropriate. The decomposition process is associated with a modeling approach, such as the PLSR, which accounts for the collinearity between predictor variables and leads to an efficient prediction model. These results are important for modeling soil properties based on topographic attributes and for spatially generalizing models that have been established over small to large areas. Thus, in the presence of nested variogram models, the correlations between variables of interest and auxiliary information should be improved by filtering out some of the spatial structures by factorial kriging. The information filtered is associated with an appropriate approach for modeling when collinearity occurs between the predictor variables and provides a suitable model for predicting and spatially generalizing a locally established model.

This work aimed to evaluate whether different types of landscape structures (undulations, lynchets and undisturbed surfaces) can be discriminated by their morphometric attributes and the soil thickness. Three models based on the factorial discriminant analysis (FDA), the multinomial logistic regression (MLR) and the classification and regression trees (CART), respectively, were developed to classify different types of landscape structures. All these statistical techniques were performed using a training sample of 586 individuals over a 17ha area located in the south-western Parisian Basin. The models developed by the CART and FDA revealed that in addition to soil thickness, the morphometric attributes slope and profile curvature significantly influence the spatial distribution of landscape structures. In addition to the variables selected by CART and FDA models, MLR model included elevation. An external validation of the classification models based on a validation sample of 148 individuals, revealed an overall well classification by CART model of 85% while those achieved with MLR and FDA models were 72% and 77%, respectively. As the predictor variables are known at all the nodes of a regular grid covering the study area; the three models developed were then used to map the landscape structures all over the 17ha area. Resulting maps revealed a total disagreement between the three models for only 3% of the study area. For more than 50% of the study area the three models predicted a similar landscape structure. For the remaining surface, at least two of the three models predicted a similar landscape structure.

Soil erosion plays an important role in sediment and carbon storage within, and exports from, catchments. In cultivated landscapes, field borders can improve the temporary storage of eroded soil particles and associated carbon, by impeding lateral soil fluxes. These local soil accumulations can lead to the development of linear landforms (such as headlands and lynchets) which will keep evolving after field border removal. A recent study performed in a representative cultivated hillslope of the SW Parisian Basin showed that 39% of the area corresponds to landforms resulting from soil accumulation induced by former and present field borders. This study demonstrated that field borders influence greatly the landscape morphology, but also the spatial distribution of soil thickness, and locally the A-horizon thickness, which are essential parameters for the prediction of SOC stocks. This study aims at characterizing and quantifying the effect of field borders and their removal on medium term topsoil erosion and deposition rates in a cultivated hillslope of the SW Parisian Basin, consolidated in 1967. Here, we used the Cs-137 technique to assess recent patterns of soil redistribution. We measured the Cs-137 inventories of 68 soil cores sampled along transects covering the area and, more specifically, linear landforms identified along present and past field borders (i.e. lynchet and undulation landforms, respectively). Then, we used a spatially-distributed Cs-137 conversion model that simulates and discriminates soil redistribution induced by water and tillage erosion processes over the last fifty years. Finally, observations and model outputs were confronted. Our results show that tillage erosion dominate the soil redistribution in the study area for the 1954-2009 period and generated about 95% (i.e. 4.50 Mg.ha􀀀1.yr􀀀1) of the total gross erosion. Soil redistribution was largely affected by the presence of current and former field borders, where hotspots areas of deposition and erosion (>20 Mg.ha􀀀1.yr􀀀1), respectively, were observed. Land consolidation contributed to the local acceleration of topsoil erosion through the conversion of storing areas into sediment generating areas. Though the general patterns of Cs-137 inventories in the area were correctly reproduced by the model, this latter performed weakly with a r2 of 0.20. Important discrepancies were associated with sampling points located along current field borders where data suggests that tillage erosion processes cannot be described as elsewhere, i.e. as a diffusive process. These specific processes implied here should be characterised and implemented into erosion models for simulating rates and patterns of topsoil redistribution in fragmented cultivated landscapes. In addition, the use of a DEM of the present-day morphology leads to the underestimation of soil erosion and storing within linear landforms which morphology seems to have greatly evolved since 1967. This study highlights the importance of present and former field borders on the patterns and intensities of topsoil erosion and deposition processes at landscape scale. This is of particular interest concerning the improvement of our knowledge on soil organic carbon patterns and on estimation of SOC stocks.

The Lake Afourgagh sediment record and facies successions provide an outstanding example of environmentally controlled carbonate sedimentation. Afourgagh is a small, shallow permanent lake located in the Middle-Atlas Mountains in Morocco in a karstic context. It is fed by ground waters that are relatively enriched in Mg resulting from the leaching of the Jurassic dolomitic bedrock of the catchment. This eutrophic lake is episodically restricted and characterized by alkaline waters with a fluctuating high Mg/Ca ratio. The maximum extension of the Holocene shoreline coincides with evidence of a lake stabilization level corresponding to the outflow of the lake through a wadi. Lakeshore terrace sediments deposited on an alluvial fan siltstone during the past ca 2500cal yr bp comprise four main facies: a littoral crust, palaeosols, palustrine silts and charophyte tufas, which reflect different environments from the shoreline toward the deeper water. In the more distal parts, the charophyte tufas display a well-expressed lamination punctuated by the development of microstromatolites on algae thalli. The mineralogical composition of the carbonates is linked to the facies. While the charophyte tufas are characterized by a relatively high content in aragonite, in addition to low-Mg calcite, the littoral crust is mainly composed of magnesite. This pattern is related to the evolving chemistry of water due to the influence of charophyte proliferation during dry summers. Calcium-carbonate precipitation on algae thalli (both bioinduced and microbially mediated) progressively induces an increase in the Mg/Ca ratio of the lake water, while the capillary evaporation of shallow ground waters causes precipitation of a magnesite precursor on the shoreline, producing magnesite during early diagenesis. This effect is characteristic of two episodes: part of the Roman Warm Period and the beginning of the Dark Age Cold Period. The carbonate mineralogy of the different depositional sequences at Afourgagh indicates lake-level and water-chemistry fluctuations under a climatic influence. Therefore, among other regional records, the Lake Afourgagh sedimentary record provides useful evidence for reconstructing these environmental changes.

Soil erosion rates in cultivated areas have intensified during the last decades leading to both on and off-site problems for farmers and rural communities. Furthermore, soil redistribution processes play an important role in sediment and carbon storage within, and exports from, cultivated catchments. This study focuses on the impact of land consolidation and changes in landscape structure on medium term soil erosion and landscape morphology within a 3.7-ha field in France. The area was consolidated in 1967 and we used the 137Cs-technique to quantify soil erosion for the period (1954–2009). We measured the 137Cs inventories of 68 soil cores sampled along transects covering the entire area and especially specific linear landforms located along both present and past field borders (i.e., lynchets and undulations landforms, respectively). These results were then confronted with the outputs of a spatially-distributed 137Cs conversion model that simulates and discriminates soil redistribution induced by water and tillage erosion processes. Our results showed that tillage processes dominated the soil redistribution in our study area for the last 55years and generated about 95% (i.e., 4.50Mg·ha−1·yr−1) of the total gross erosion in the field. Furthermore, we demonstrated that soil redistribution was largely affected by the presence of current and also former field borders, where hotspots areas of erosion and deposition (>20Mg·ha−1·yr−1) were concentrated. Land consolidation contributed to the acceleration of soil erosion through the conversion of depositional areas into sediment generating areas. Although the conversion model was able to reproduce the general tendencies observed in the patterns of 137Cs inventories, the model performance was relatively poor with a r2 of 0.20. Discrepancies were identified and associated with sampling points located along the current field borders. Our data suggests that tillage erosion processes near field boundaries cannot be described as a typical diffusive process. These processes near field boundaries should be characterised and taken into account in a future version of the model to accurately simulate rates and patterns of past soil redistribution in fragmented cultivated hillslopes. We also showed that the use of an accurate DEM resulting from LIDAR data, based on present-day topography, leads to the underestimation of soil redistribution rates by the model, especially in this landscape submitted to recent and important morphological changes. Our results have important implications for the simulation of tillage erosion processes and our understanding of soil redistribution processes in complex cultivated areas. This is of particular interest to improve our knowledge and prediction of patterns of soil physical parameters, such as carbon storage or water content, particularly sensitive to surface erosion and landscape structuration.

Soils and landscapes evolve simultaneously. Soil evolution is controlled by redistribution and transformation processes influenced by topographic and climatic parameters, with also a major contribution of management strategies. The perennial landscape features have a strong influence on soil spatial distribution (geometry) and soil genesis. Building landscapes which enhance soil resilience to degradation processes and increase soil services appears as a promising way to adapt to forthcoming climatic and land use evolutions. The presentation aims to synthetize major results from a research program nicknamed Landsoil which focused on the evolution of agricultural soils over medium time scales (decades to centuries) in relation to changing conditions of land use and climate. Precise study of the soil 3D organization in three contrasted landscapes (Brittany, Touraine, Languedoc-Roussillon) enabled to link soil redistribution in space to landscape components (field geometry, hedges or ditches network) and their past evolution. A dynamic and high resolution spatial modeling approach was developed coupling erosion processes and soil organic matter evolution and was calibrated over past evolution using dating techniques (Cs137, C14, OSL). The resulting Landsoil model was afterwards applied in a prospective manner under different scenarios of land use and climate change over the 21th century. Indicators of soil vulnerability and soil resilience were defined and tested by the comparison of several prospective scenarios applied on a same landscape and by comparison of the contrasted landscapes