Closure of a hyperextended system in an orogenic lithospheric pop‐up,Western Pyrenees: The role of mantle buttressing and rift structural inheritance

The Early Cretaceous hyperextended Mauléon rift is localized in the north‐western Pyrenean orogen. We infer the Tertiary evolution of the Mauléon basin through the restoration of a 153‐km‐long crustal‐scale balanced cross‐section of the Pyrenean belt, which documents at least 67 km (31%) of orogenic shortening in the Western Pyrenees. Initial shortening, accommodated through inversion of inherited crustal structures, led to formation of a pop‐up structure, in which the opposite edges underwent similar shortening with different tectonic reactivation styles, localized versus. distributed. Underthrusting of the Iberian margin accommodated further convergence, forming the Axial Zone antiformal stack of crustal nappes within a lithospheric pop‐up. Thin‐skinned and thick‐skinned structures propagated outward from the heart of this pop‐up, a block of strong mantle acting as a buttress inhibiting complete inversion of the Mauléon rift basin.     

Environmental conservation and the production of new territories: the example of French départements

Very important initiatives have been taken and policies have been adopted in the European Union to protect areas of great importance for threatened species and habitats. Protected areas differ broadly in terms of category, natural conditions and administrative organisation, from international initiative such as Biosphere Reserves, European ones with Natura 2000 network until the institution of national and regional protected areas. In France, the administrative subdivisions known as “départements” were created with the French Revolution in the end of the eighteenth century; in 1985 an original and autonomous procedure to establish special protected areas, called “Sensitive Natural Spaces” (SNS) was devolved to them. The scope of this paper is to present an overview of these devolved powers which enable French départements to create protected areas and to levy a departmental tax on sensitive natural spaces (DTSNS). We statistically studied some parameters by multivariate methods in order to explain the choices of this policy by the départements. The huge variations in the way these powers are implemented prove the development of new environmental territories.     

Oxygen isotope compositions of phosphate from arvicoline teeth and Quaternary climatic changes, Gigny, French Jura

Oxygen isotope compositions of biogenic phosphates from mammals are widely used as proxies of the isotopic compositions of meteoric waters that are roughly linearly related to the air temperature at high- and mid-latitudes. An oxygen isotope fractionation equation was determined by using present-day European arvicoline (rodents) tooth phosphate: δ¹⁸O_p = 20.98(±0.59) + 0.572(±0.065) δ¹⁸O_w. This fractionation equation was applied to the Late Pleistocene karstic sequence of Gigny, French Jura. Comparison between the oxygen isotope compositions of arvicoline tooth phosphate and Greenland ice core records suggests to reconsider the previously established hypothetical chronology of the sequence. According to the δ¹⁸O value of meteoric water-mean air temperature relationships, the δ¹⁸O value of arvicoline teeth records variations in mean air temperatures that range from 0° to 15°C.     

Vertical Structure of the Urban Boundary Layer over Marseille Under Sea-Breeze Conditions

During the UBL-ESCOMPTE program (June–July 2001), intensive observations were performed in Marseille (France). In particular, a Doppler lidar, located in the north of the city, provided radial velocity measurements on a 6-km radius area in the lowest 3 km of the troposphere. Thus, it is well adapted to document the vertical structure of the atmosphere above complex terrain, notably in Marseille, which is bordered by the Mediterranean sea and framed by numerous massifs. The present study focuses on the last day of the intensive observation period 2 (26 June 2001), which is characterized by a weak synoptic pressure gradient favouring the development of thermal circulations. Under such conditions, a complex stratification of the atmosphere is observed. Three-dimensional numerical simulations, with the Méso-NH atmospheric model including the town energy balance (TEB) urban parameterization, are conducted over south-eastern France. A complete evaluation of the model outputs was already performed at both regional and city scales. Here, the 250-m resolution outputs describing the vertical structure of the atmosphere above the Marseille area are compared to the Doppler lidar data, for which the spatial resolution is comparable. This joint analysis underscores the consistency between the atmospheric boundary layer (ABL) observed by the Doppler lidar and that modelled by Méso-NH. The observations and simulations reveal the presence of a shallow sea breeze (SSB) superimposed on a deep sea breeze (DSB) above Marseille during daytime. Because of the step-like shape of the Marseille coastline, the SSB is organized in two branches of different directions, which converge above the city centre. The analysis of the 250-m wind fields shows evidence of the role of the local topography on the local dynamics. Indeed, the topography tends to reinforce the SSB while it weakens the DSB. The ABL is directly affected by the different sea-breeze circulations, while the urban effects appear to be negligible.