Biostratigraphic distribution of orbitolinids in the ammonite biozones (Urgonian platform of southeastern France). Part 2: Barremian p.p.

The biostratigraphic distribution of orbitolinids for the Barremian of SE France proposed hereafter is calibrated on the ammonite biozonation. This work is based on the study of eleven sections with orbitolinids associated to macrofossils (ammonites and/or echinids) significant in terms of biostratigraphy or overlain with levels bearing the above macrofossils.

Sediment export in marly badland catchments modulated by frost-cracking intensity, Draix-Bléone Critical Zone Observatory, SE France

At the interface between the lithosphere and the atmosphere, the critical zone records the complex interactions between erosion, climate, geologic substrate and life, and can be directly monitored. Long data records collected in the sparsely vegetated, steep marly badland catchments of the Draix-Bléone Critical Zone Observatory (CZO), SE France, allow analysing potential climatic controls on long-term regolith dynamics and sediment export. Although widely accepted as a first-order control, rainfall variability does not fully explain the observed inter-annual variability in sediment export, suggesting that regolith production and its controls may modulate the observed pattern of sediment export. Here, we define sediment-export anomalies as the residuals from a predictive model with annual rainfall intensity above a threshold as the control. We then use continuous soil-temperature data, recorded at different locations over multiple years, to highlight the role of frost weathering in regolith production. Several proxies for different frost-weathering processes have been calculated from these data and compared to the sediment-export anomalies, with careful consideration of field data quality. Our results suggest that frost-cracking intensity (linked to ice segregation) can explain about half (47–64 %) of the sediment-export anomalies. In contrast, the number of freeze-thaw cycles (linked to volumetric expansion) has only a minor impact on catchment sediment response. The time spent below 0 °C also correlates well with the sediment-export anomalies and requires fewer field data to be calculated than the frost-cracking intensity. Thus, frost-weathering processes modulate sediment export by controlling regolith production in these catchments and should be taken into account when building a predictive model of sediment export from these badlands under a changing climate.

Sediment export in marly badland catchments controlled by frost cracking intensity, Draix-Bléone CZO, SE France

<p>At the interface between the lithosphere and the atmosphere, the critical zone records the complex interactions between erosion, climate, geologic substrate and life, and can be directly monitored. The sparsely vegetated, steep marly badland catchments of the Draix-Bléone Critical Zone Observatory (CZO), SE France are characterised by high quantities of exported sediment and rapid morphologic changes. Characterizing and understanding the physical weathering processes in this area are key to predict the temporal variability of regolith production and sediment flux, as well as their evolution under changing climate conditions.</p><p>Long data records collected in the Draix-Bléone CZO allow analysing long-term regolith dynamics and climatic control on sediment export. Although widely accepted as the first order control, rainfall variability does not fully explain the observed yearly variability in sediment export, suggesting that regolith production and its controls may contribute to the observed pattern of sediment export. Within the several factors that can influence marls weathering (soil moisture, density, chemical weathering), this study focuses on continuous temperature data, recorded at different locations over multiple years, and aims to highlight the role of frost cracking in regolith production. Several proxies for frost cracking intensity have been calculated from these data and compared to the sediment export anomalies, with careful consideration of field data quality. Our initial results suggest that frost-cracking processes have a significant impact on catchment sediment response and should be taken into account when building a predictive model of sediment export from these catchments under a changing climate.</p>

Geobotanical characterisation of the Trifolion squamosi nom. corr. alliance (class. Juncetea maritimi) in Catalonia and the Western Mediterranean

We present a summary of part of the phytogeographic results described in the author’s PhD thesis. In this case, we characterise and validate several syntaxa of subsaline meadows in the Trifolion squamosi nom. corr. alliance (class. Juncetea maritimi) in Catalonia (incl. NE Spain and SE France) and in other regions of the Western Mediterranean (N Algeria, Languedoc and Provence). In total, we study six syntaxa in geobotanical terms, based on synthetic tables and factor analyses of correspondence published previously in the thesis: one alliance (Trifolion squamosi), two associations and three subassociations (Agropyro-Trifolietum subass. typicum, subass. festucetosum comb. nova, subass. brachypodietosum nova; Festucetum arundinaceae).

Global Processes, Regional Dynamics?

The goal of this paper is to discuss the validity of radiocarbon dates as a source of knowledge for explaining social dynamics over a large region and a long period of time. We have carefully selected c. 1000 14C dates for the time interval 8000–4000 cal BC within the northwestern Mediterranean area (NE Iberian Peninsula, SE France, N Italy) and Switzerland. Using statistical analysis, we have modelled the summed probability distribution of those dates for each of the analysed ecoregion and discussed the rhythms of neolithisation in these regions and the probability of social contact between previous Mesolithic and new Neolithic populations.