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Peer Reviewed
See detailHolocene dust record in a NW European peat bog: A multiproxy approach
Allan, Mohammed ULg; Le Roux, Gael; Verheyden, Sophie et al

Conference (2013, August 28)

Dust deposition in southern Belgium is estimated from the geochemical signature of an ombrotrophic bog. The analyses of Rare Earth Elements (REE) and lithogenic element concentrations as well as Nd ... [more ▼]

Dust deposition in southern Belgium is estimated from the geochemical signature of an ombrotrophic bog. The analyses of Rare Earth Elements (REE) and lithogenic element concentrations as well as Nd isotopes were performed by HR-ICP-MS and MC-ICP-MS respectively, in a  6 m peat section representing 5300 years, from 30 BC to 5300 BC dated by the 14C method. REE concentration variations in peat samples were used as a dust proxy and the Nd isotopes to trace the sources. Peat humification and testate amoebae were used to evaluate hydroclimatic conditions. The range of dust deposition varied from 0.03 to 4 g m-2 yr-1. The highest dust fluxes were observed from 800 to 600 BC, and from 3200 to 2800 BC and correspond to cold periods. The Nd values show large variability, between -5 and –13, identifying three major sources of dust: local soils, distal volcanic and desert particles. By comparing our results with the dust recorded in other peat bogs and ice cores from different latitudes, we evidence that the Misten peat is a valid archive for dust deposition. [less ▲]

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See detailHolocene environmental changes in lake sediments from Northern Chilean Patagonia
Nuttin; Fagel, Nathalie ULg; Brogniet et al

Poster (2009)

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See detailHolocene environmental changes in lake sediments from Northern Chilean Patagonia (45-48°S)
Nuttin, L.; Fagel, Nathalie ULg; Bertrand, S. et al

Poster (2009)

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See detailHolocene evolution of deep circulation in the northern North Atlantic traced by Sm, Nd and Pb isotopes and bulk sediment mineralogy
Fagel, Nathalie ULg; Mattielli, Nadine ULg

in Paleoceanography (2011), 26

Bulk mineralogy, Sm, Nd and Pb elemental and isotopic compositions of the clay-size fraction of Holocene sediments were analysed in 3 deep North Atlantic cores to trace the particle provenance. The aims ... [more ▼]

Bulk mineralogy, Sm, Nd and Pb elemental and isotopic compositions of the clay-size fraction of Holocene sediments were analysed in 3 deep North Atlantic cores to trace the particle provenance. The aims of the present paper are to identify the origin of the particles driven by deep currents and to reconstruct deep circulation changes over the Holocene in the North Atlantic. The three cores are retrieved in fracture zones; two of them are located in the Island Basin along the gyre of North Atlantic Deep Water, and the third core is located off the present deep circulation gyre in the Labrador Sea. Whereas sedimentary supplies in the Labrador Sea were constantly derived from proximal sources, the geochemical mixing trends in the Iceland Basin samples indicate pronounced changes in the relative contribution of continental margin inputs over the past 6 kyr. Supplies from Western European margin that sharply increased at 6 kyr were progressively diluted by a larger contribution of Scandinavian margins over the last 3 kyr. Changes in composition of the particles imply significant reorganisation of paleocirculation of the deep North Atlantic components in the Eastern basins: mainly reorganisations for both Iceland-Scotland Overflow Water (ISOW) and Norwegian Sea Overflow Water (NSOW). Moreover the unusual Bulk mineralogy, Sm, Nd and Pb elemental and isotopic compositions of the clay-size fraction of Holocene sediments were analysed in 3 deep North Atlantic cores to trace the particle provenance. The aims of the present paper are to identify the origin of the particles driven by deep currents and to reconstruct deep circulation changes over the Holocene in the North Atlantic. The three cores are retrieved in fracture zones; two of them are located in the Island Basin along the gyre of North Atlantic Deep Water, and the third core is located off the present deep circulation gyre in the Labrador Sea. Whereas sedimentary supplies in the Labrador Sea were constantly derived from proximal sources, the geochemical mixing trends in the Iceland Basin samples indicate pronounced changes in the relative contribution of continental margin inputs over the past 6 kyr. Supplies from western European margin that sharply increased at 6 kyr were progressively diluted by a larger contribution of Scandinavian margins over the last 3 kyr. Changes in composition of the particles imply significant reorganisation of paleocirculation of the deep North Atlantic components in the eastern basins: mainly reorganisations for both Iceland-Scotland Overflow Water (ISOW) and Norwegian Sea Overflow Water (NSOW). Moreover the unusual Pb isotopic composition of the oldest sediments from the southern Iceland Basin indicates that distal supplies from Greenland margin were driven into the Iceland Basin, supporting a deep connection between Labrador Sea and Iceland Basin through the Charlie Gibbs Fracture Zone prior the Holocene Transition period. [less ▲]

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See detailHolocene floodplain deposition and scale effects in a typical European upland catchment : A case study from the Amblève catchment, Ardennes (Belgium)
Notebaert, Bastiaan; Verstraeten, Gert; Houbrechts, Geoffrey ULg et al

in Holocene (2013), 23(8), 1184-1197

This study quantifies Holocene alluvial sediment deposition in the Belgian Amblève catchment (1080 km2), situated in the Ardennes uplands. An extended coring data set is used for a quantitative ... [more ▼]

This study quantifies Holocene alluvial sediment deposition in the Belgian Amblève catchment (1080 km2), situated in the Ardennes uplands. An extended coring data set is used for a quantitative description and a quantification of the alluvial depositions. The floodplains fall into three main types: the upper and lower floodplains and the steep reaches. Total Holocene alluvial sediment deposition amounts to 32 Tg, or 0.029 Tg/km2. Dating of sediments using iron slag as tracer shows that on average 42% of contemporary storage was accumulated during the last 600 years. Radiocarbon dating of fluvial deposits at eight sites in the catchment confirms that the majority of the sediment is relatively recent. The increased sedimentation rates for this period are related to anthropogenic land use, possibly enhanced by climatic variations. A fluvial sediment budget was constructed for this 600 yr time period and shows that export from the catchment has about the same importance as storage in the floodplains, while lateral reworking of existing floodplain deposits only affects half the quantity of sediments. Overall, floodplain sediment storage in the Amblève catchment, comparable with other upland catchments, is of lesser importance compared with catchments dominated by loess. This can mainly be explained by lower sediment supply resulting from less intense anthropogenic land use, despite the higher sediment transport efficiency through the fluvial system. Floodplain sediment storage is scale-dependent, with initially a sharp increase in catchment area-specific sediment deposition, followed by a steady decrease with increasing catchment area. [less ▲]

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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; Mattielli et al

Conference (2007)

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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 detailHolocene palaoenvironmental records in PN speleothem (Han-sur-Lesse cave, southern Belgium
Allan, Mohammed ULg; Fagel, Nathalie ULg; Verheyden, Sophie

Conference (2015, April 16)

Detailed reference viewed: 23 (8 ULg)
See detailHolocene paleoenvironmental reconstructions from Belgian peatbog
Allan, Mohammed ULg; VERHEYDEN, sophie; Le roux, gael et al

Conference (2016, January 27)

Atmospheric deposition is an important part of the global climate system, and plays a key role in the marine and terrestrial biogeochemical cycles as a source for major and trace nutrient elements ... [more ▼]

Atmospheric deposition is an important part of the global climate system, and plays a key role in the marine and terrestrial biogeochemical cycles as a source for major and trace nutrient elements. Reconstruction of atmospheric deposition is crucial to understand the effects of the increased atmospheric depositions induced by humans on the environment and to help understanding Holocene climate variability. This study investigated potential paleoenvironmental proxies provided by major and trace elements and stable isotopes compositions of peat bogs. Peat bog cores were collected from Hautes-Fagnes plateau (Misten bog) (SE-Belgium). The analyses of Rare Earth Elements (REE) and lithogenic element concentrations as well as Nd isotopes were performed by HR-ICP-MS and MC-ICP-MS respectively, in a  7 m peat section representing 7300 years, dated by 210Pb and 14C methods. The Misten bog is highly affected by atmospheric supplies (natural and anthropogenic) and can be used to establish the changes in atmospheric dust during the Mid-Late Holocene. Dust fluxes show pronounced increase at 3200-2800BC, 600BC, AD600, 1000AD, 1200AD and from 1700 AD corresponding to local and regional human activities combined with climate change. Peat humification and testate amoebae were used to evaluate hydroclimatic conditions. The Nd values show large variability, between -5 and –13, identifying three major sources of dust: local soils, distal volcanic and desert particles. Our results provide evidence that climate forcing may be detected in ombrotrophic peat, even for the historical period that is characterised by a mixed climate-human control. [less ▲]

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Peer Reviewed
See detailHolocene paleoenvironmental reconstructions from speleothem and peat bog archives
Allan, Mohammed ULg; VERHEYDEN; CRUCIFIX, Michel et al

Poster (2016, January 28)

The geological materials (speleothems and peatbogs) presented in Belgium (Hautes-Fagnes Plateau, Ardennes caves) are interesting archives for atmospheric pollution record and climate variability. Both ... [more ▼]

The geological materials (speleothems and peatbogs) presented in Belgium (Hautes-Fagnes Plateau, Ardennes caves) are interesting archives for atmospheric pollution record and climate variability. Both archives are easily dated (U/Th and counting for laminated speleothems, 210Pb and 14C for peatbogs), have a high temporal resolution (decadal to seasonal), contain multiple measurable parameters (elemental geochemistry, stable isotopes, radiogenic Nd and Pb isotopes, pollens, rates of peat humification, luminescence and thickness of laminated speleothems) and depending on environmental conditions of temperature and / or humidity. The aim of this study is to determine the sensitivity of both archives (speleothems and peatbogs) to human perturbations and climate changes. Our ultimate goal is to contribute to a better understanding of natural interglacial climate variability by generating and confronting high resolution paleoclimate reconstructions from 2 continental archives. [less ▲]

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See detailHolocene record of atmospheric flux by geochemical and Pb isostopes signatures in a Belgian Hautes Fagnes peat bog: Preliminary results
Gerard; De Vleeschouwer, F.; Mattielli, N. et al

in Geochimica et Cosmochimica Acta (2004), 68(11), 485-485

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See detailHolocene record of atmospheric flux by geochemical and Pb isostopes signatures in a Belgian Hautes Fagnes peat bog: Preliminary results
Gerard; De Vleeschouwer, F.; Mattielli, N. et al

in Geochimica et Cosmochimica Acta (2004), 68(11), 485-485

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

in Geochimica et Cosmochimica Acta (2008), 72(12), 535-535

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Peer Reviewed
See detailHolocene sediment deposition in contrasting Belgian catchments
Notebaert, Batsiaan; Houbrechts, Geoffrey ULg; Verstraeten, Gert et al

in LUCIFS Workshop December 2008: Programme and Abstracts (2008)

Holocene alluvial sediment deposition was studied in several contrasting Belgian catchments: the Geul (380 km2) and its tributary the Gulp (47 km2), the Amblève (1070 km2) and its tributary the Lienne ... [more ▼]

Holocene alluvial sediment deposition was studied in several contrasting Belgian catchments: the Geul (380 km2) and its tributary the Gulp (47 km2), the Amblève (1070 km2) and its tributary the Lienne (148 km²), and the Dijle (750 km2). These catchments have a comparable Holocene climatic evolution, but they differ largely in land use history. Detailed total Holocene sediments deposition was assessed for each catchment using more then 1000 hand augerings. Detailed radiocarbon dating of fluvial deposits was performed in the Dijle catchment, while iron slag was used as a tracer for sediments deposited after 1350 AD in the Lienne catchment. For the Geul River the presence of lead contamination, originating from 19th century mining activities, were used as a tracer. Results show that sediment deposition is much largest in the Dijle catchment (4.6 Mg/ha catchment area) then in the Gulp catchment (1.3 Mg/ha catchment area), while the lowest deposition is found in the Amblève catchment (0.2 Mg/ha catchment area). It is clear that these differences are mainly due to historical land use differences, although it can not be excluded that part of these differences are due to physical factors, especially for the Amblève catchment. For the latter catchment, the distribution of iron slags in the floodplain sediments showed that large parts of the alluvial plane were eroded after 1350 AD, and thus that there is no net aggradation as for the Dijle and Gulp floodplain. Remobilization of floodplain sediment in the Amblève makes it also difficult to estimate Holocene erosion rates. Nevertheless it is clear that an important part of the sedimentation took place after the Middle Ages, and that during Medieval times the river changed from a system with two or more channels to a system with one single channel. This is probably related to increasing deforestation after 1350 AD. Dating results of the Dijle floodplain show that the sedimentation rates are largely influenced by land use with main deposition after the Middle Ages. There is a gradual increase in sedimentation rate since Neolithic times and each new cultural period is recognized by an increase in sedimentation rate related to the intensification of land use. Several sites show that sedimentation rates have recently decreased, probably due to a reduction in cropland area. 12 Dating of the Geul River floodplain suggests a high sedimentation rate during the 19th century and lower rates for more recent times, which can be related to the more intense 19th century land combined with mobilization of sediments by the mining activities, which ended at the end of that century. From the data collected in these catchments it is clear that land use changes are the main driving factors for accelerated alluvial sediment deposition rates, although climate fluctuations can have influenced the impact of land use changes. [less ▲]

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See detailThe holodisc distance transform and its applications in image analysis
Pirard, Eric ULg

in Microscopy, Microanalysis, Microstructures (1996), 7

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