Search results for "ORC"
showing 10 items of 4623 documents
High-resolution 40Ar/39Ar chronostratigraphy of the post-caldera (<20 ka) volcanic activity at Pantelleria, Sicily Strait
2011
Abstract The island of Pantelleria (Sicily Strait), the type locality for pantellerite, has been the locus of major caldera-forming eruptions that culminated, ca. 50 ka ago, in the formation of the Cinque Denti caldera produced by the Green Tuff eruption. The post-caldera silicic activity since that time has been mostly confined inside the caldera and consists of smaller-energy eruptions represented by more than twenty coalescing pantelleritic centers structurally controlled by resurgence and trapdoor faulting of the caldera floor. A high-resolution 40Ar/39Ar study was conducted on key units spanning the recent (post-20 ka) intracaldera activity to better characterize the present-day status…
Models and data analysis tools for the Solar Orbiter mission
2020
All authors: Rouillard, A. P.; Pinto, R. F.; Vourlidas, A.; De Groof, A.; Thompson, W. T.; Bemporad, A.; Dolei, S.; Indurain, M.; Buchlin, E.; Sasso, C.; Spadaro, D.; Dalmasse, K.; Hirzberger, J.; Zouganelis, I.; Strugarek, A.; Brun, A. S.; Alexandre, M.; Berghmans, D.; Raouafi, N. E.; Wiegelmann, T.; Pagano, P.; Arge, C. N.; Nieves-Chinchilla, T.; Lavarra, M.; Poirier, N.; Amari, T.; Aran, A.; Andretta, V.; Antonucci, E.; Anastasiadis, A.; Auchère, F.; Bellot Rubio, L.; Nicula, B.; Bonnin, X.; Bouchemit, M.; Budnik, E.; Caminade, S.; Cecconi, B.; Carlyle, J.; Cernuda, I.; Davila, J. M.; Etesi, L.; Espinosa Lara, F.; Fedorov, A.; Fineschi, S.; Fludra, A.; Génot, V.; Georgoulis, M. K.; Gilbe…
Effect of the Ordovician paleogeography on the (in)stability of the climate.
2014
The Ordovician Period (485–443 Ma) is characterized by abundant evidence for continental-sized ice sheets. Modeling studies published so far require a sharp CO2 drawdown to initiate this glaciation. They mostly used non-dynamic slab mixed-layer ocean models. Here, we use a general circulation model with coupled components for ocean, atmosphere, and sea ice to examine the response of Ordovician climate to changes in CO2 and paleogeography. We conduct experiments for a wide range of CO2 (from 16 to 2 times the preindustrial atmospheric CO2 level (PAL)) and for two continental configurations (at 470 and at 450 Ma) mimicking the Middle and the Late Ordovician conditions. We find that the temper…
Insolation cycles as a major control equatorial Indian Ocean primary production
1997
Analysis of a continuous sedimentary record taken in the Maldives indicates that strong primary production fluctuations (70 to 390 grams of carbon per square meter per year) have occurred in the equatorial Indian Ocean during the past 910,000 years. The record of primary production is coherent and in phase with the February equatorial insolation, whereas it shows diverse phase behavior with δ 18 O, depending on the orbital frequency (eccentricity, obliquity, or precession) examined. These observations imply a direct control of productivity in the equatorial oceanic system by insolation. In the equatorial Indian Ocean, productivity is driven by the wind intensity of westerlies, which is rel…
Orbital forcing of tree-ring data
2012
Based on an analysis of maximum latewood density data from northern Scandinavia, along with published dendrochronological records, this study finds evidence that previous tree-ring-reliant reconstructions of large-scale near-surface air temperature underestimated long-term pre-industrial warmth during Medieval and Roman times. Solar insolation changes, resulting from long-term oscillations of orbital configurations1, are an important driver of Holocene climate2,3. The forcing is substantial over the past 2,000 years, up to four times as large as the 1.6 W m−2 net anthropogenic forcing since 1750 (ref. 4), but the trend varies considerably over time, space and with season5. Using numerous hi…
Winter climate signal in boreal clastic-biogenic varves : a comprehensive analysis of three varved records from 1890 to 1990 AD with meteorological a…
2017
Clastic-biogenic varves are widely used for reconstructing past climate: in boreal environments, the accumulation of minerogenic clasts on the lake floor is generally considered a proxy for past variations in spring floods reflecting previous winter conditions. However, the physical mechanisms behind this winter climate sensitivity and the influence of catchment type on the varve formation are not fully investigated. Here, we present a winter climate record inferred from the clastic laminae of three lakes located on the region of fine-grained tills in Eastern Finland spanning from AD 1890 to 1990. The minerogenic varve data are compared with instrumental meteorological and hydrological time…
Volcanic climate forcing preceding the inception of the Younger Dryas: Implications for tracing the Laacher See eruption
2021
Climatic warming from the last glacial maximum to the current interglacial period was punctuated by a similar to 1300 years long cold period, commonly referred to as the Younger Dryas (YD). Several hypotheses have been proposed for the mechanism triggering the abrupt inception of the YD, including freshwater forcing, an extra-terrestrial impact, and aerosols from volcanic eruptions. Here, we use synchronised sulphate and sulphur records from both Greenland and Antarctic ice cores to reconstruct volcanic forcing between 13,200-12,800 a BPGICC05 (years before 1950 CE on the Greenland Ice Core Chronology 2005; GICC05). This continuous reconstruction of stratospheric sulphur injections highligh…
Les offrandes animales de la nécropole celtique de Ludas-Varjù Dulo (Hongrie)
2006
International audience; Des restes animaux ont été recueillis dans trente six sépultures (dont une inhumation) de la nécropole du troisième siècle avant notre ère de Ludas-Varjù. Ces restes présentent des états de conservation assez contrastés : certains sont très altérés, alors que d'autres sont très bien préservés. Ces différences semblent dues à des circonstances locales (profondeur, nature du terrain ?). Ces restes, comme l'ensemble du mobilier, ont fait l'objet de relevés graphiques et photographiques. Tout cela constitue des conditions favorables à leur étude. Cette présentation ne concerne que les restes animaux déposés directement dans les sépultures. En effet, seule une petite part…
Effects of cooking on mollusk shell structure and chemistry: Implications for archeology and paleoenvironmental reconstruction
2016
Mollusk shells excavated from archeological sites have been used to reconstruct paleoenvironment, human foraging, and migratory patterns. To retrieve information on past environment or human behavior, chemical signatures such as oxygen stable isotopes (δ18Oshell) are analyzed. Shell archeological remains usually represent food waste. Thermal treatments such as boiling and roasting may influence shell structure and biochemical composition. However, little is known about the relationship between changes at macro-, microstructural and chemical levels. This work is a calibration study on modern Phorcus (Osilinus) turbinatus shells. A simulation of two different cooking methods (boiling and roas…
New data about the landscape of the first occupation of Mallorca: Coval Simó (Escorca, Mallorca)
2020
The Coval Simó shelter provides some of the oldest evidence for settlement on the island of Mallorca and the Balearic archipelago. It also has the peculiarity of being a habitat in a mountain area, so that the human groups that settled there had to adapt their agricultural and farming system to this environment. The plant remains (wood charcoal and seeds) recovered in the occupation levels allow us to address these issues, since they are the result of the different activities developed in this cavity: fuel for domestic activities, food for livestock, etc. The results of this study show that between the III and II millennium cal BC, an agricultural system based on livestock and cereal farmi…