Search results for "Global change"
showing 9 items of 639 documents
Caractérisation et diagenèse thermique des roches mères pétrolières de la série des Schistes d'âge néocomien moyen-barrémien dans le bassin intérieur…
2006
8 pages; International audience
Un bassin extensif formé pendant la fonte de la calotte glaciaire hirnantienne : le bassin ordovico-silurien de Kandi (Nord Bénin, Sud Niger)
2006
Le long de la bordure occidentale du bassin de Kandi, la sédimentation détritique continentale de base, correspondant à la formation de Wéré, est préservée dans des paléovallées limitées par des failles d'orientation moyenne N20°E, héritées de l'orogenèse panafricaine. Le remplissage sédimentaire de ces paléovallées est représenté par des dépôts conglomératiques et bréchiques de tills glaciaires marquant la base de la série, évoluant verticalement et latéralement vers l'Est à des grès fluviatiles. Ces dépôts continentaux, d'âge supposé ordovicien supérieur, passent verticalement à des grès tidaux et des grès et siltites subtidaux de la Formation de Kandi, d'âge ordovicien terminal à silurie…
Compte-rendu de l'atelier de lancement de la Phase 1 du programme "Trames noires du Massif central" (IPAMAC)
2022
Phase 2 du programme "Trames noires du Massif central" (IPAMAC, 2020). Compte-rendu intermédiaire. Visite du Parc naturel régional de Millevaches en …
2020
Experimental Constraints on the Deep Magma Feeding System at StromboliVolcano, Italy
2009
International audience; New experiments have been performed on a high-K basalt (PST-9) from Stromboli volcano, Italy, to constrain the physical conditions of golden pumice magmas at their storage level and discuss their petrogenesis. Fluid-present, H2O- and CO2-bearing, near-liquidus experiments were performed at 11508C between 100 and 400MPa and under oxidizing conditions. Glasses were analyzed by Fourier transform IR spectroscopy and their H2O and CO2 concentrations compared with those in glass inclusions.Most glass inclusions cluster near the 200MPa isobar, suggesting entrapment at a depth of ~8 km. Golden pumice magmas have viscosities of 7.9 Pa s and densities of 2.48-2.57 g/cm3. Compo…
The influence of ENSO on South Africa winter rainfall
2011
International audience; We analysed the relationship between El Niño Southern Oscillation (ENSO) and South Africa austral winter rainfall using a 682 raingauges daily rainfall database documenting the period 1950-1999. The May, June and July (MJJ) seasonal rainfall amount shows a positive correlation with the Niño3.4 index that becomes significant since the mid 70's. Wet spells properties (length, frequency and intensity) at the raingauge scale indicate that high (low) MJJ seasonal rainfall amounts recorded during El Niño (La Niña) events are the result of longer (shorter) wet spells in the Cape Town area and more (less) frequent wet spells north of 33°S. Wet spells with daily rainfall amou…
Doctoral studies in global time and change - female doctoral student and individual lifecourse in Finland
2013
Multiple global changes in the form of knowledge and the change in the doctoral education create the need to examine the current practices of doctoral degree. The change forces discussion about the future of doctoral education and the future of the prospective doctors. The doctoral education has to answer the demands set for it. Forming a comprehensive understanding requires an examination at the micro and macro level. In this article I examine the lifecourse of the under 40-year-old female doctoral student with a family and the significance of doctoral studies at the individual level. I concentrate on the personal lifecourse experiences of the women and on the chronological stories which a…
Unraveling environmental histories from skeletal diaries — Advances in sclerochronology
2013
High-resolution proxy archives from aquatic settings are essential to better understand processes and mechanisms of global change. During the last decade, it has become increasingly evident that calcified tissues of bivalve mollusks and cold-water corals, in particular, can significantly increase our knowledge of seasonal to multi-decadal paleoclimate and paleoenvironmental variability in the extratropical oceans and coastal marine settings. Daily, tidal, fortnightly and annual growth patterns of periodically formed skeletal hard parts provide a means to place the proxy record in a precise temporal context. Their extreme longevity coupled with the running similarity between growth increment…
Carbon cycle and sea-water palaeotemperature evolution at the Middle-Late Jurassic transition, eastern Paris Basin (France).
2014
14 pages; International audience; A very high-resolution carbon and oxygen stable isotope analysis (bulk-carbonate) of a biostratigraphically well-constrained Callovian-Oxfordian series is provided here for the first time. The homogeneity of the clayey series and the weak diagenetic alteration allow the isotopic signal variations to be considered as primary in origin. A prominent and brief negative excursion in the δ13C curve (−2‰), occurring at the start of the Middle Callovian (Jason Zone - Obductum Subzone) and correlated regionally, suggests a possible methane release. The increasing δ13C values thereafter up to the Early Oxfordian, concomitant with a warming episode, highlight the buri…