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See detailA 17,900-year multi-proxy lacustrine record of Lago Puyehue (Chilean Lake District): introduction
De Batist, Marc; Fagel, Nathalie ULg; Loutre, Marie-France et al

in Journal of Paleolimnology (2008), 39(2), 151-161

This paper introduces the background and main results of a research project aimed at unravelling the paleolimnological and paleoclimatological history of Lago Puyehue (40 degrees S, Lake District, Chile ... [more ▼]

This paper introduces the background and main results of a research project aimed at unravelling the paleolimnological and paleoclimatological history of Lago Puyehue (40 degrees S, Lake District, Chile) since the Last Glacial Maximum (LGM), based on the study of several sediment cores from the lake and on extensive fieldwork in the lake catchment. The longest record was obtained in an 11-m-long piston core. An age-depth model was established by AMS C-14 dating, Pb-210 and Cs-237 measurements, identification of event-deposits, and varve-counting for the past 600 years. The core extends back to 17,915 cal. yr. BP, and the seismic data indicate that an open-lake sedimentary environment already existed several thousands of years before that. The core was submitted to a multi-proxy analysis, including sedimentology, mineralogy, grain-size, major geochemistry and organic geochemistry (C/N ratio, delta C-13), loss-on-ignition, magnetic susceptibility, diatom analysis and palynology. Along-core variations in sediment composition reveal that the area of Lago Puyehue was characterized since the LGM by a series of rapid climate fluctuations superimposed on a long-term warming trend. Identified climate fluctuations confirm a.o. the existence of a Late-Glacial cold reversal predating the northern-hemisphere Younger Dryas cold period by 500-1,000 years, as well as the existence of an early southern-hemisphere Holocene climatic optimum. Varve-thickness analyses over the past 600 years reveal periodicities similar to those associated with the El Nino Southern Oscillation and the Pacific Decadal Oscillation, as well as intervals with increased precipitation, related to an intensification of the El Nino impact during the southern-hemisphere equivalent of the Little Ice Age. [less ▲]

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See detailGeochemical and Pb isotopic signature of peaty sediments from central-south Chile: Identification of particle supplies over the Holocene
De Vleeschouwer, François ULg; Ibanez, Maud; Mattielli, Nadine et al

in Journal of the Chilean Chemical Society [=JCCS] (2008), 53(3), 1640-1649

Two cores from tephra rich peat soils of the Chilean Lake District were investigated for mineral source and potential anthropogenic impact using elemental geochemistry, including rare earth elements, and ... [more ▼]

Two cores from tephra rich peat soils of the Chilean Lake District were investigated for mineral source and potential anthropogenic impact using elemental geochemistry, including rare earth elements, and lead isotopes. The dominant particle source to the area are the Trumaos which are the local ando soils derived from the weathering of volcanic deposits. In Galletue, although short term events of enhanced particle inputs occur, elemental and isotopic signatures show that the Trumaos are the only particle source to the area. In San Pablo de Tregua, punctual events of crustal particle inputs are recorded in Pb enrichment factors and isotopic profiles, reflecting a long range crustal involvement. This site also records the inception of the anthropogenic in the area in recent samples of which Pb enrichment factors and lead isotopic signatures shift drastically. [less ▲]

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See detailLong term mobilisation of chemical elements in tephra-rich peat (NE Iceland)
De Vleeschouwer, François ULg; Lanoe, Brigitte Van Vliet; Fagel, Nathalie ULg

in Applied Geochemistry (2008), 23(12), 3819-3839

This paper presents geochemical profiles of a tephra-bearing minerotrophic peat column from NE-Iceland obtained using various elemental analyses of the solid phase and the pore water. The influence of ... [more ▼]

This paper presents geochemical profiles of a tephra-bearing minerotrophic peat column from NE-Iceland obtained using various elemental analyses of the solid phase and the pore water. The influence of tephra grain size, thickness and composition of each tephra on the peat geochemistry was investigated. Interpretations are supported by a statistical approach, in particular by autocorrelation, and by microscopy observations. Minerotrophic peat geochemistry may be strongly dependent upon post-depositional mobilization and possible leaching of elements as demonstrated by Fe and trace metal concentration profiles. Chemical elements, and more specifically potentially harmful metals, can be slowly leached out of volcanic falls during their weathering and re-accumulate downwards. It is emphasised that a tephra deposit can act as an active geochemical barrier, blocking downward elemental movements and leading to the formation of enriched layers. In this study, the formation of poorly amorphous Fe phases above the Hekla 3 tephra is shown. These poorly crystalline Fe phases scavenged Ni. (c) 2008 Elsevier Ltd. All rights reserved. [less ▲]

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See detailRoman road pollution assessed by elemental and lead isotope geochemistry in East Belgium
Renson, Virginie; Fagel, Nathalie ULg; Mattielli, Nadine et al

in Applied Geochemistry (2008), 23(12), 3253-3266

The ability of inorganic geochemistry to record environmental change and especially human impact has been evidenced by several studies across Europe, especially in peat, where it is possible to record the ... [more ▼]

The ability of inorganic geochemistry to record environmental change and especially human impact has been evidenced by several studies across Europe, especially in peat, where it is possible to record the impact of agriculture, mining and other industries. However, despite the numerous investigations on the impact of ancient human activities such as ore mining and smelting, little attention has been paid to geochemistry as a tool to solve problems of palaeopollution in the surroundings of archaeological sites. This paper presents geochemical evidence of the impact of a possible early Roman road built in SE Belgian peatland. Increased Zn and Pb concentrations suggest that Pb-Zn ores were transported on the road, Lead isotope analyses suggest that these ores are locally derived, being compatible with those found in the nearby Pb-Zn ore deposits from East Belgium. Present results provide direct evidence that East Belgian Pb-Zn ores were already being mined during Roman times, i.e. earlier than previously suspected (i.e. 14th century) and that Zn appears to be relatively immobile here. On a broader scale, it also demonstrates that such an early road already had an impact on the environment in terms of metal pollution. This paper enlarges on the range of possibilities offered by geochemistry in the field of geoarchaeology. (C) 2008 Elsevier Ltd. All rights reserved. [less ▲]

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See detailHolocene Records of Aerosols in Continental Environments (HoRACE)
Le Roux; De Vleeschouwer, F.; Cherbukin et al

Conference (2008)

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See detailDevelopment of a "pre-anthropogenic" peat standard for geochemical, paleo-environmental and archaeological investigations
Le Roux; De Vleeschouwer, F.; Cheburkin et al

Poster (2008)

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See detailRecent climatic instability in Poland and effect of Little Ice Age on human activities
De Vleeschouwer, F.; Lamentovicz, M.; Piotrowska, N. et al

Poster (2008)

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See detailDevelopment and application of high-resolution petrography on resin-impregnated Holocene peat columns to detect and analyse tephras, cryptotephras, and other materials
De Vleeschouwer, François ULg; van Vliet-Lanoe, Brigitte; Fagel, Nathalie ULg et al

in Quaternary International (2008), 178

We describe the potential for high-resolution detection, observation and chemical analysis of tephras and cryptotephras in freeze-dried and resin-impregnated peat sections. Special attention is drawn to ... [more ▼]

We describe the potential for high-resolution detection, observation and chemical analysis of tephras and cryptotephras in freeze-dried and resin-impregnated peat sections. Special attention is drawn to tephra grain alteration products, sensitive to standard lab treatment, but preserved using an impregnation technique developed here. Resulting blocks and thin sections provide a continuous archive of tephras that can be investigated through a wide range of non-destructive techniques encompassing polarising and fluorescence microscopy, scanning electron microscopy with/without elemental analysis, and XRF-based core scanning. (c) 2007 Elsevier Ltd and INQUA. All rights reserved. [less ▲]

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See detailTraces of the last earthquake sequence (1939-1944) along NAF from lacustrine sediments.
Avsar, U.; Boes, X.; Hubert-Ferrari, A. et al

Poster (2008)

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See detailSedimentological Fingerprints of Recent Earthquakes in Lake Sediments: A Case Study on the North Anatolian Fault (NAF), Turkey
Avsar, U.; Boes, X.; Hubert-Ferrari, A. et al

Poster (2008)

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See detailHolocene instabilities in GIN sea overflows based on mineralogical and Nd/Pb isotopic sedimentary records
Simon, Q.; Fagel, Nathalie ULg; Jennings, A. et al

Poster (2008)

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See detailLacustrine record of Late Pleistocene and Holocene climate evolution, volcanism and seismic activity in Lake Puyehue (Chilean Lake District)
De Batist, M.; Fagel, Nathalie ULg; Loutre, M. F. et al

Book published by Journal of Paleolimnology (2008)

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See detailHolocene records of regional dust deposition using peat bogs
Le Roux, G.; De Vleeschouwer, F.; Cheburkin, A. et al

Poster (2008)

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See detailNd and Pb isotopic signatures of detrital fractions from Labrador Sea and Iceland Basin sediments: Deep oceanic circulation changes over the Holocene
Fagel, Nathalie ULg; Brasseur; Mattielli, N. et al

in Geochimica et Cosmochimica Acta (2008), 72(12), 251-251

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See detailClay-mineral record in Lake Baikal sediments: The Holocene and Late Glacial transition
Fagel, Nathalie ULg; Boes, Xavier

in Palaeogeography, Palaeoclimatology, Palaeoecology (2008), 259(2-3), 230-243

We analyse the clay-mineralogical composition of two 1-m long cores from elevated plateaus in the southern and northern basins of Lake Baikal. Our aim is to test the limits of classically used clay ... [more ▼]

We analyse the clay-mineralogical composition of two 1-m long cores from elevated plateaus in the southern and northern basins of Lake Baikal. Our aim is to test the limits of classically used clay proxies for climate reconstructions. Mineralogical signature is determined by X-ray diffraction on oriented aggregates from Holocene and Late Glacial sediments. Mineralogical results are presented on a palaeomagnetic-derived time scale. Sampling at a centimeter resolution allows for a sub-millenial order reconstruction. The evolution of clay-derived climate proxies (smectite/illite peak intensity ratio, S/I) is compared between the two locations, with respect to other climate reconstructions for the Lake Baikal area and Siberia. During the Late Glacial punctual increases of S/I are related to changes of particle source rather than any climate change. At both sites the most intense chemical weathering conditions occured during the Subboreal, lagging the Eurasian middle Atlantic climate optimum. S/I follows a gradual but irregular increase through the Holocene, probably related to slow warming favourable to the development of the Siberian soils. The different sensitivity to hydrolysing conditions in northern and southern sites can be explained by a combination of local lithological and topographical parameters. (c) 2007 Elsevier B.V. All rights reserved. [less ▲]

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