Colloque sur l'hydrogéologie karstique du Massif du Vercors - Grenoble 16 novembre 1968.

Travaux du Laboratoire de géologie de la Faculté des Sciences de Grenoble - Mémoires n° 8 188 p.Les contributions sur l'hydrogéologie karstique du Vercors sont rassemblées dans ce mémoire : hydrogéologie du synclinal de Villars de Lans, lac de Bouvante etc ... karst du Vercors ( la Luire etc..

Apport de la géologie, de l'hydrogéologie et des isotopes de l'environnement à la connaissance des “nappes en creux” du Grand Yaéré (Nord Cameroun)

International audiencePiezometric depressions, common in sub-Saharan Africa, are major hydrogeological anomalies manifested by closed curves, pronounced hollows and dips attaining several tens of meters below the regional water table level. The Logone- Chari-Chad piezometric map reveals piezometric anomalies that have been interpreted as depressed aquifers. The depth of the water table is 60 m in the Tagawa-Am Talia axis, 40 m between Louba-Louba and Andirni and 30 m around Yagoua. Factors linked to evaporation are generally thought to be responsible for these depressed zones. The objective of this study (based on the saturated zone) was: 1) to place the Logone-Chari-Chad piezometric anomalies in their hydrogeological settings, and 2) to evaluate the use of environmental isotopes to explain their formation processes. To achieve our goal, 27 water supply points (8 boreholes and 19 wells) were selected from the borders and centre of the Logone-Chari-Chad depression. Samples were collected between 1989 and 1991. Measurements performed in the field involved static water levels, whereas the laboratory analyses 18O, ²H and 3H were performed at the International Atomic Energy Agency (IAEA) laboratory in Vienna, within the framework of the project RAF/8/012 funded by IAEA. The new geological and hydrogeological data demonstrate that in the depressed zone of the piezometric surface, the aquifer has two layers. In contrast, the Logone-Chari-Chad piezometric map was previously drawn considering the aquifer as a single-layer. From a hydrochemical point of view, the groundwater in the Logone-Chari-Chad aquifer is stratified: calcium bicarbonate type water was found at the surface (shallow groundwater), whereas sodium carbonate type water was found at depth (deeper groundwater). Seasonal piezometric fluctuations of 1.5 to 3 m have been observed in the shallow groundwater. In the deeper groundwater, they range from 0.20 to 0.30 m. The difference in the values of water table fluctuation leads not only to variations in the mode of groundwater circulation, but also to variations in the hydrodynamic properties of aquifers, such as transmissivity. The distribution in stable isotope contents (18O, ²H and 3H) confirmed the compartmentalization of aquifers. The correlation between 3H and 18O showed that there are two water types, with different recharge modes and episodes. On the border of the depression, shallow groundwater pinches out on the semi-permeable substratum, resulting in a tritium content greater than 4 UT. In the depression axis, there is deeper groundwater with a tritium content below 4 UT. The relationship between ²H and 18O shows that the enrichment effects of evaporation at the time of recharge are very pronounced only in the shallow groundwater, where the static level does not exceed 20 m below the soil surface. The closed piezometric depressions, whose deepest point attains 60 m below the soil surface, cannot be explained by the presence of intense evaporation. The variation in tritium content with respect to the static level shows that in the depressed zone, the first 20 m are characterized by a tritium content greater than 4 UT, whereas at depths of 30 m or more, tritium contents are lower than 4 UT. The absence of dependence between shallow and deep piezometric levels invalidates the interpretation of great water depths proposed in previous studies of the piezometric depression of the Logone-Chari-Chad water table. Thus, the hypothesis that the Logone-Chari-Chad is a single-layer system should be abandoned. The future construction of the piezometric map of the Logone-Chari-Chad water table should take into account the structure and lithology of the two superimposed layers

Étude géologique de la couverture mésozoïque du dôme de la Mure (Isère) et des régions annexes

Ce travail concerne le Dôme de La Mure et sa couverture mésozoïque: situation dans les Alpes occidentales :Trias, Lias et Dogger .Cette étude permet de mettre en évidence la continuité du style tectonique de la zone au cours des époques géologiques successives.Pas de résum

Analysis of risk factors for complications and adverse obstetrical outcomes in women with Takayasu arteritis: a French retrospective study and literature review

International audienceObjective Takayasu arteritis (TAK) is a large vessel vasculitis affecting young women of childbearing age. The outcome of pregnancies in TAK patients, factors associated with maternal and foetal complications and adverse outcomes were analysed. Methods All pregnancies in women with a TAK diagnosis were retrospectively included from 20 French hospitals providing care for TAK, until August 2015. Results The study consisted of 43 pregnancies in 33 women, including 29 with a pre-existing TAK diagnosis and 4 diagnosed during pregnancy. Complications were observed in 20 pregnancies (47%), including 35% with arterial hypertension (n = 15), 9% with pre-eclampsia (n = 4), 2% with HELLP syndrome (n = 1) and 14% with intrauterine growth restriction (IUGR, n = 6, leading in one case to a medically indicated termination of pregnancy). There were 42 live births (98%) at a median term of 38 [27-42] weeks gestation including 9 before 37 weeks (21%). The median birth weight was 2940 [610-4310] grams. Five children (12%) required transfer to a neonatal intensive care unit. One premature boy (27 weeks gestation) died after 2 days. Treatment during pregnancy included steroids (n = 25/43; 58%), azathioprine (n = 9/43; 21%) and infliximab (n = 1/43; 2%). The risk of developing arterial hypertension during pregnancy was associated with previous chronic arterial hypertension and with an infra-diaphragmatic vasculitis injury (P = 0.01 and P = 0.04, respectively). No correlation was reported between TAK activity and any of the obstetrical complications described in the study. Conclusion This study showed a high rate of adverse obstetrical complications without significant impact on live birth rates. Pregnancy did not appear to influence TAK disease activity..Pregnancy did not appear to influence TA disease activity