References of "Fagel, Nathalie"
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See detailTechnological behaviour of Cretaceous and Pliocene clays of northern Morocco used in fired brick manufacturing
El Ouahabi, Meriam ULg; Daoudi, Lahcen; Fagel, Nathalie ULg

in Journal of Materials and Environmental Science (in press)

Northern Morocco has an important local ceramic industry. Twenty-three Craterous and Pliocene clays from Tangier area (Northern Morocco) were studied to test their suitability as raw material for fired ... [more ▼]

Northern Morocco has an important local ceramic industry. Twenty-three Craterous and Pliocene clays from Tangier area (Northern Morocco) were studied to test their suitability as raw material for fired brick production. To assess their behaviour, the chemical composition, specific surface area (SSA), cation exchange capacity (CEC), and apparent density of clays were determined. The chemical composition consisted mainly of SiO2 (32 – 60%), Al2O3 (7 – 30%), and CaO (0.5 – 32%). SSA and CEC values of all the samples were low. The apparent density, pore volume, and micropore values were almost similar. Clay bricks were prepared by forming and shaping, and then fired in the range of 800 – 1100°C. Firing shrinkage, loss on mass and water absorption capacity were done in order to characterize clays after firing. Most of the clay samples have the necessary properties for the manufacturing of brick products. However, some clay samples were above the norm of loss on weight, due mainly to their high amount of carbonates. Furthermore, some kaolinitic samples from Pliocene blue marls and Cretaceous marls are inappropriate for building-related brick fabrication, because of the development of portlandite in brick, when in contact with moisture of the air. However, it will be necessary to mix them with other clays with little or no carbonate to dilute their carbonates content and then enhance their workability. [less ▲]

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See detailLacustrine clay mineral assemblages as a proxy for land-use and climate changes over the last 4 kyr: The Amik Lake case study, Southern Turkey
El Ouahabi, Meriam ULg; Hubert, Aurelia ULg; Fagel, Nathalie ULg

in Quaternary International (in press)

Lake sediments are sensitive to landscape changes and most of these changes seem to be modulated by land-use (anthropogenic factors) coupled to palaeoenvironmental/palaeoclimatic changes. In its detrital ... [more ▼]

Lake sediments are sensitive to landscape changes and most of these changes seem to be modulated by land-use (anthropogenic factors) coupled to palaeoenvironmental/palaeoclimatic changes. In its detrital fraction, the lacustrine sediments record the history of soil erosion within its catchment via the inputs of clays and others detrital products. Within a Mediterranean context, the study investigates the upper sediments infilling the central part of the Amik basin in southern Turkey. This tectonic basin was occupied and exploited by modern human at least since 6000-7000 BC. We focus on the clay mineralogy (x-ray diffraction on oriented aggregates) and magnetic susceptibility measurements (Bartington) of the sedimentary record in the area over the last 4000 years, to assess environmental changes in relation with the different land uses and/or weathering during the successive Bronze, Iron, Roman, Islamic/Ottoman and Modern civilizations. The clay fraction of Amik Lake sediments comprises smectite, kaolinite, illite, chlorite and chlorite/smectite mixed layers that are the inherited clay phases. A relative change in abundance and crystallinity and chemistry of illite attests that environmental conditions evolved in the Amik Plain from the Bronze to Modern Age in relation with climates and/or land-use changes. The history of the Amik Lake reveals different soil erosion episode. The most intense erosion phase occurred during the Bronze/Iron Ages as indicated by the clay and magnetic susceptibility proxies. The Roman period was an exceptional period with soil erosion products arriving from the watershed, probably due the water channelization. A reduction of soil erosion occurred during the post Roman period until nowadays. Significant pedogenesis transformations are evidenced, especially during the Islamic/Ottoman periods suggesting intense chemical weathering conditions related to climate change. [less ▲]

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See detailReconstitution des paléoenvironnements et des activités humaines à partir de l’étude de sédiments prélevés dans le Cap Corse (Corse, France)
Fagel, Nathalie ULg; Fontaine, François ULg; Pleuger, Elisa ULg et al

in Ghilardi, Mathieu (Ed.) La géoarchéologie des îles de Méditerranée (in press)

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See detailBelgian speleothem records Holocene cold events?
Allan, Mohammed ULg; Deliège, Adrien ULg; Nicolay, Samuel ULg et al

Poster (2017, May 12)

Speleothem is now regarded as valuable archive of climatic conditions on the continents, offering a number of advantages relative to other continental climate proxy recorders such as lake sediments and ... [more ▼]

Speleothem is now regarded as valuable archive of climatic conditions on the continents, offering a number of advantages relative to other continental climate proxy recorders such as lake sediments and peat cores. High spatial resolution measurements of Mg, Al, Sr, Ba were realized by using laser-ablation inductively coupled plasma mass spectrometry in the Belgian Pere Noel cave. A stalagmite from the Pere Noel (PN) cave representing 12000 years dated by U/Th method. Trace element variations in speleothem are a reflection of hydrochemical conditions. These changes were interpreted as indications of changes in climate in the Han-sur-Lesse region. The similar patterns found in δ 18O, δ 13C and chemical composition along the Pere Noel stalagmite suggests that trace elements in speleothems have the potential to provide high resolution insights into palaeoclimatic variability during the Holocene. A deeper analysis reveals several periods of significant rapid climate change during the Holocene (at 10.7-9.2 ka, 8.2-7.9 ka, 7.2-6.2 ka, 4.8-4.5 ka, and 3-2.4 ka BP), which are similar to the cold events detected from different natural paleoclimate archivers. A comparison between the geochemical analysis of Père Noël speleothem and solar activity (sunspot number) reveals a significant correlation. Spectral analysis methods reveal common solar periodicities (Gleissberg cycle, de Vries cycle, unnamed 500 year, Eddy cycles, and Hallstatt cycle). The geochemical analyses have the potential to prove that PN speleothem is sensitive to changes in solar activity on centennial and millennial timescales during the Holocene. [less ▲]

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See detailImplication for the use of benthic foraminifera as bio-indicators of pollution: The case study of the Northern coast of Sfax (South eastern Tunisia)
Lamourou, Ali ULg; Touir, Jamel; Fagel, Nathalie ULg

in YNHM 4TH YOUNG NATURAL HISTORY SCIENTISTS' MEETING (2017, February 12)

The use of foraminifers as bioindicators of pollution in coastal and paralic environments has undergone a very fast development. Among various criteria, morphological anomalies are sometimes considered as ... [more ▼]

The use of foraminifers as bioindicators of pollution in coastal and paralic environments has undergone a very fast development. Among various criteria, morphological anomalies are sometimes considered as pollution indicators. This paper presents a synthesis of the studies correlating foraminiferal assemblages and environmental concerns. Sediment cores retrieved along the northern coast of Sfax (Tunisia) are used to monitor the response of benthic foraminifera to modern pollution and environmental stress. Sediment samples were separated immediately after collection for benthic foraminifera analysis. Binocular microscope and the Scanning Electron Microscope (SEM) were carried out to identify the most significant, normal or deformed, specimens. All observations confirmed that foraminifera may be used as indicators of pollution after deconvoluting from natural impacts. The most sensitive foraminifera identified in the study area are Ammonia tepida, Ammonia beccarii, Elphidium crispum, Peneroplis pertususles Miliolidae, Peneroplis pertusus et Rosalina sp and Peneroplis planatus. The morphological study of benthic foraminifera from surface sediments attests for the pollution of the actual coast. This pollution is recorded in the benthic foraminifera tests mainly as shell deformations, chambers or streaks or abnormal colors. [less ▲]

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See detailReconstructing the Holocene depositional environments along the northern coast of Sfax (Tunisia): Mineralogical and sedimentological approaches
Lamourou, Ali ULg; Touir, Jamel; Fagel, Nathalie ULg

in Journal of African Earth Sciences (2017), 129C

A sedimentological and mineralogical study of sedimentary cores allows reconstructing the evolution of depositional environments along the Northern coast of Sfax (Tunisia). The aim is identifying the ... [more ▼]

A sedimentological and mineralogical study of sedimentary cores allows reconstructing the evolution of depositional environments along the Northern coast of Sfax (Tunisia). The aim is identifying the factors controlling the sedimentation from the Holocene to the Present. Three 30-m sediment cores collected by drilling at 30 meter water depth were analyzed for their color, magnetic susceptibility signal, grain size by laser diffraction, organic matter content by loss of ignition, carbonate content by calcimetry and mineralogy by X-ray diffraction on bulk powder and clay < 2 m. The three cores broadly present the same sedimentological and mineralogical features. Microscopical observations of petrographic slides allow to identifying six main sedimentary facies. Bulk mineralogical assemblages comprise clay minerals, quartz, calcite, gypsum and K-feldspars. The main change concerns the carbonate content that mimics the bioclaste abundance and dilute the detrital minerals (clay minerals, quartz and feldspars). The gypsum mainly occurs in the lower sedimentary columns (SC12 and SC9) and in the upper/middle of core SC6. The clay fraction is made of a mixture of kaolinite, illite, smectite and palygorskite with no clear variation through core depth. Both grain-size parameters and magnetic susceptibility profile indicates a sharp transition in the upper 2 to 5 m of the sedimentological columns. Coarse, sandy to gravely, sediments characterized by a low magnetic susceptibility signal are replaced by fine bioclastic-rich clayey sediments. The analysis of vertical succession of depositional facies showed a fluvial depositional environment (coastal plain) basically marked by fluvial channels and inundation plains at the bottom of all cores. Core-top sediments, however, record a littoral marine environment characterized by sand depositions rich in gastropods, lamellibranches and algæ. Depositional facies, sedimentological and mineralogical parameters are consistent with a transition from a continental, fluviatile, depositional environment, with some emersion phases marked by the gypsum precipitation to a marine littoral environment. Such evolution is consistent with a relative sea-level rise which flooded the fluvial system at the coastal plain during the Holocene, in agreement with sea-level fluctuations in southeast Tunisia during the Holocene. [less ▲]

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See detailLa pollution atmosphérique enregistrée dans les stalagmites de Han-sur-Lesse
Allan, Mohammed ULg; Fagel, Nathalie ULg; Verheyden, sophie

Conference (2016, November 12)

Les spéléothèmes sont maintenant considérées comme précieuses archives climatiques et environnementales sur les continents, offrant un certain nombre d'avantages par rapport à d'autres archives ... [more ▼]

Les spéléothèmes sont maintenant considérées comme précieuses archives climatiques et environnementales sur les continents, offrant un certain nombre d'avantages par rapport à d'autres archives continentales (les sédiments lacustres, les carottes de glace….). Cette archive peut être aisément datables (U/Th, comptage de lamines et 14C), et présentent une haute résolution temporelle (décennale à saisonnière). Cependant, leur potentiel pour l'enregistrement de la pollution de l'environnement est largement inexploré et principalement axé sur la quantification des contributions d'aérosols dans des grottes touristiques. Cette étude est un des premières études qui utilise les spéléothèmes pour retracer la pollution atmosphérique. Basé sur deux spéléothèmes collectées dans la grotte de Han-sur-Lesse (S-Belgique), ce travail a deux objectifs : 1) le premier est de quantifier la concentration du Pb pour la dernière 250 ans, 2) le second objectif est de définir les sources anthropiques prédominantes de Pb en utilisant les rapports isotopiques du Pb et en basant sur les comparaisons avec les données historiques des activités anthropogéniques en Europe et la Belgique. Les concentrations en éléments traces (Al et Pb) (mesurées par LA-ICP-MS et ICP-MS) et les rapports isotopiques du Pb (mesurées par MC-ICP-MS) permettent d'identifier trois intervalles caractérisés par un enrichissement particulier en Pb : de 1880 à 1905 AD, de 1945 à 1965 AD, et de 1975 à 1990 AD. Les spéléothèmes montrent des changements similaires au niveau historique de la pollution atmosphérique connu en Belgique. Les rapports isotopiques du Pb distinguent clairement les sources de Pb et confirment que le charbon et la combustion de l'essence combinée avec des activités métallurgiques régionales étaient les sources prédominantes de la pollution au cours des 250 dernières années. Cette étude met l'accent sur la capacité des spéléothèmes d’enregistrer la pollution atmosphérique. [less ▲]

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See detailHigh-temperature and quantitative XRD study of typical Westerwald clays (Germany)
Fontaine, François ULg; Fagel, Nathalie ULg

Poster (2016, July 05)

The Westerwald is one of the largest and oldest clay mining area of Germany. Those deposits were formed during the Eocene and Oligocene as a result of the weathering, erosion and redeposition of Devonian ... [more ▼]

The Westerwald is one of the largest and oldest clay mining area of Germany. Those deposits were formed during the Eocene and Oligocene as a result of the weathering, erosion and redeposition of Devonian rocks. During the Miocene, intense volcanic activities led to a large basalt cover, protecting the clays from the erosion. The fine fraction is mainly composed of kaolinite and illite, with the possible presence of interstratified I S. Other minerals such as quartz, feldspars, hematite, goethite or anatase are present in variable concentrations. Four typical Westerwald clays were chosen for this study: kaolinite-rich clay, kaolinite-illite clay, a red and a yellow firing clays. The first goal is to perform quantitative XRD using two different methods and to compare them: reference intensity ratio (RIR) and Rietveld (using Topas and BGMN). The second goal is the study of those samples using high-temperature XRD (HTXRD). The samples were heated up to 1250°C and a XRD pattern was obtained in situ every 100°C. The results show the temperatures of vitrification and formation of mullite and cristobalite varying from one sample to another, which is mainly linked to their flux concentration. [less ▲]

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See detailGeochemistry and mineralogy approaches to characterize brick and its lake sediments sources: Antioch Roman City (Southern Turkey)
El Ouahabi, Meriam ULg; Hubert, Aurelia ULg; Benjelloun, Yacine et al

Poster (2016, July)

The Roman aqueduct of Antioch-on-the-Orontes (Southern Turkey) is situated close to the Antioch city. This last is located near the Amik Lake (Lake of Antioch) and close to the junction between the active ... [more ▼]

The Roman aqueduct of Antioch-on-the-Orontes (Southern Turkey) is situated close to the Antioch city. This last is located near the Amik Lake (Lake of Antioch) and close to the junction between the active Dead Sea fault and the East Anatolian fault. During the Roman period, the Amik Plain was more densely occupied than at any time in its history [1]. The study focuses on the bricks and the lake sediments characterization in order to determine the source area as well as the technical production used at this period. For this purpose, several bricks were sampled on different parts of the city's aqueducts. Furthermore, a core of about 6 m of sediments was also collected from the dried Amik Lake. The bricks were characterized through a mineralogical (XRD) and chemical (PIXE-PIGE) approaches. Unfired clay fraction remained as inclusion in the brick was separated and then analysed using XRD. Geochemical composition and clay mineralogy were performed on the raw sediments from the Amik Lake in order to compare the source area. Technological test will be performed on the raw clay sediments from the Amik Lake in the purpose to understand the production techniques used at this time. The age of the brick production was previously dated to the Roman Period [2]. The synthesis of all the data attested the Amik Lake sediment as the raw material for the bricks of the aqueduct. Clay mineral composition from the Roman period deposited in the lake is smectite, illite, kaolinite and small amount of mixed-layer clays. The similar clays composition is found in the remained clays on the brick used for the aqueduct construction. Fast and heterogeneous firing practice characterized the manufacturing of these materials due to the rapid need for the materials during the post-seismic repairs after earthquakes that are mentioned in historical written works. [1] J. Casana, Geomorphology, 101, 429-442 (2008) [2] Y. Benjelloun, J. de Sigoyer, J. Carlut, A. Hubert-Ferrari, H. Dessales, H. Pamir, V. Karabacak, Comptes Rendus Geoscience, 347, 170-180 (2015) [less ▲]

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See detailPaleoenvironmental implications in the dried lake sediments (Amik Lake, Southern Turkey)
El Ouahabi, Meriam ULg; Hubert, Aurelia ULg; Vander Auwera, Jacqueline ULg et al

Poster (2016, July)

The Amik Basin in the Eastern Mediterranean region has been continuously inhabited since 6000 – 7000 BC. The study focuses on the sedimentary record of the Amik Lake located in the central part of the ... [more ▼]

The Amik Basin in the Eastern Mediterranean region has been continuously inhabited since 6000 – 7000 BC. The study focuses on the sedimentary record of the Amik Lake located in the central part of the basin. Our objective is to constrain major paleo-environmental changes in the area over the last 4000 years and to unravel possible human impacts on the sedimentation. A diverse array of complementary methods was applied on the 6 m long record. Mineralogical (XRD), and geochemical (XRF) analyses were performed. The age of the record is constrained combining radionuclide and radiocarbon dating. A high sedimentation rate of 0.12 cm/yr was inferred at the studied site. The 4000 years (since ~1800 BC) long record shows that significant fluctuations of the lake level and the riverine system inflow into the Amik Lake occurred. The Late Bronze lowstand led to punctual dryings of the lake at the end of the Bronze/Iron Age transition. At that time, the rivers yielded a large terrigenous input linked to strong soil erosion related mainly to deforestation and exploitation of mineral resources. During the Roman and later periods, upland soils were partly depleted and the riverine system completely transformed by channelization (anthropic) that led to a marshification of the Amik Basin [1]. Chemical and mineralogical composition of sediments is quite diversified reflecting the significant geological variation of drainage basins. Periods with strong aggradation linked to major increase in erosion were identified and characterized by high amount of Cr, Ni and Zr. Levels relatively rich in fluorite, richterite, enstatite, hornblende and chrysotile are a result of the erosion of the ophiolitic rocks from the surrounding Amanos Mountains. These levels are interpreted as periods of relatively high physical erosion, while more humid periods led to more intensive weathering. Consequently, the dominance of kaolinite, muscovite/illite and talc indicates a climate with contrasting seasons. During the most recent period a marked increase in terrigenous minerals associated with a rise in dolomite indicates ungoing erosion as well as the drying-out of the lake. [1] T.J. Wilkinson, L. Rayne, Water History, 2, 115-144 (2010). [less ▲]

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See detailHolocene paleoclimate reconstructions from belgian continental archives
Allan, Mohammed ULg; VERHEYDEN, sophie; CRUCIFIX, Michel et al

Poster (2016, June 28)

Speleothems and peatbogs presented in Belgium are interesting archives for atmospheric pollution record and climate variability. Both archives are reliable continental environmental archives of high ... [more ▼]

Speleothems and peatbogs presented in Belgium are interesting archives for atmospheric pollution record and climate variability. Both archives are reliable continental environmental archives of high interest due to their dating possibilities and their possibility to preserve multi-proxy records of environmental and climatic dynamics. Combining studies on speleothems and peatbogs from the same area will provide an age-constrained reconstruction of climatic variability at annual resolution for key intervals of the Holocene. The reconstructed precipitation and temperature curves in NW European settings, as proposed in HOPES, are essential to better constrain the Northern Hemisphere climatic record and to test climate models. Our strategy is derived from a comparative study of two continental archives speleothems and peatbogs. Time series of elemental and stable isotope geochemistry will be established for the 2 archives. For peatbog, the reconstructions of temperature (derived from stable C and O isotope), precipitation (derived from humification) and dust flux (from elementary geochemical signature) would track climate changes with subdecadal resolution. As an innovative part, Laser Ablation analyse of elemental geochemistry on impregnated peat section will allow to reach an annual resolution in the dust flux. For speleothems, records of temperature (derived from oxygen and carbon isotopic composition of calcite) and effective rainfall (derived from geochemical ratios) would reach a seasonal resolution. [less ▲]

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See detailReconstructing the Holocene depositional environments along the northern coast of Sfax (Tunisia): mineralogical and sedimentological approaches
Lamourou, Ali ULg; Touir, Jamel; Fagel, Nathalie ULg

Conference (2016, May 20)

This study aims to reconstruct the Holocene to modern depositional environments and the evolution over the main controls of the sedimentation along the northern coast of Sfax (Tunisia) using three ... [more ▼]

This study aims to reconstruct the Holocene to modern depositional environments and the evolution over the main controls of the sedimentation along the northern coast of Sfax (Tunisia) using three sediment cores retrieved at 30 meters water depth by SEACNVS (Société d'Étude et d'Aménagement des Côtes Nord de la Ville de Sfax). The identification of different types of depositional environments was mainly based on field work,mineralogical and sedimentological analyses of core sediments. Mineralogical analysis by X-ray diffraction have been done on bulk powder and on oriented aggregate of the clay < 2 microns fraction,particle size distribution,magnetic susceptibility was measured on opened cores with a Bartington MS2Epoint sensor and Loss-On-Ignition (LOI) was measured after 24h at 105°C (water content, density), after 4h at 550°C (organic matter content) and after 2h at 950°C (inorganic carbonate).The mineralogical composition is made by clay minerals, quartz, calcite, gypsum and K-feldspar.The mineralogy of <2μm clay fraction show a mixture of kaolinite,illite, smectite and palygorskite. As harp change in the magnetic susceptibility profiles records the transition from a marine to a continental depositional environment. The marine domain is characterized by lower magnetic susceptibility values and coarser sedimentary grain than the continental domain. The vertical succession of depositional facies is made by two contrasted environments: a fluvial depositional environment (coastal plain) marked by channels and inundation plains at the in the lower section of all cores; a littoral marine environment characterized by fossil sand depositions in the upper section. The sand is rich in gastropods, lamellibranches, algæ and benthic fauna (Ammonia tepida, Ammonia beccarii, Elphidium crispum, Peneroplis pertususles Miliolidae, Peneroplis pertusus , Rosalina sp and Peneroplis planatus). This facies evolution indicates a relative sea-level rise which flooded the fluvial system at the coastal plain during the late Holocene. Results allowed the reconstruction of the Holocene shoreline variations along the northern coast of Sfax and complete the established records of sea-level fluctuations in southeast Tunisia during the last 10 000 years. [less ▲]

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See detailDepositional Sequences of the Late Pleistocene Shoreline System, Bor Basin, Southern-Central Anatolia: Implications for Reconstructing Lake Level Changes
Bayer Altın, Türkan; El Ouahabi, Meriam ULg; Fagel, Nathalie ULg

Conference (2016, May 08)

The Bor Basin is located in the east part of the Konya-Ereğli Plain occupied by Pleistocene lake (Fig. 1). Paleo-shoreline deposits rising western margins of the basin marked the former extent of a now ... [more ▼]

The Bor Basin is located in the east part of the Konya-Ereğli Plain occupied by Pleistocene lake (Fig. 1). Paleo-shoreline deposits rising western margins of the basin marked the former extent of a now desiccated Late Pleistocene Lake. This study evaluates the former lake level changes and the sequential evolution of a shoreline system that developed at the western margin with lacustrine fills of the Bor paleolake near Zengen settlement. The fills belongs to alluvial fans formed by streams coming from the high volcanic mountains located within the northern part of the basin. The sediment sequence of the fan reflects receded and extended levels of the former lake. 23 samples were obtained at the sand-quarry representing of various facies of the lacustrine fills. These samples were analyzed for mineralogical characterization, using XRD and their CaCO3 values were quantified. According to analysis, three evident different phases of weathering were distinguished in this deposit (Fig. 2). Weathering conditions occurred at the bottom of the profile (level 7) with the appearance of the vermiculite and illite/smectite mixed layer clays. Aridification phases occurred at the level of sample 16 with the appearance of the palygorskite. At the shallow levels from the samples 21 to 22, another aridification phase occurred attested by the appearance of the palygorskite, the mixed layers clays (illite/smectite) and the neoformation of the chlorite by weathering. The palygorskite occurrence showed only in the clay fraction (<2µm) associated with dolomite levels which support its secondary formation during dry periods and pedogenetic transformation. Pedogenesis conditions were attested also by the presence of the mixed layers clays at those levels. [less ▲]

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See detailThe last millenia sedimentary record of Lago Esponja from Northern Chilean Patagonia
Fagel, Nathalie ULg; Alvarez, Denisse; Araneda, Alberto et al

Poster (2016, April 20)

We evaluate the climate and environmental variability of Northern Chilean Patagonia during the Last Millennia, using a multi-proxy analysis of a sediment core from Lago Esponja (45°09’S, 72°08’W). The ... [more ▼]

We evaluate the climate and environmental variability of Northern Chilean Patagonia during the Last Millennia, using a multi-proxy analysis of a sediment core from Lago Esponja (45°09’S, 72°08’W). The lake is located in the region of Aysen del General Carlos Ibanez del Campo, in NW Patagonia. The study focuses on a multiproxy analysis of sedimentary records. The longest core (150 cm long) was collected in 2014 at 40 m depth. The sediment, which is composed of light brown organic-rich clayey silt, was analyzed for sedimentology (grain size, magnetic susceptibility organic matter and biogenic silica content), mineralogy (X-ray diffraction) and geochemistry (elemental and isotopic analyses of C and N, XRF core-scaner at 1 mm resolution). The radiocarbon ages, measured on 3 macro-remains, demonstrate that the core covers the last 6.700 years. The sedimentation rate ranges between 0.1 mm/yr in the lower section (100-150 cm) and 0.4 mm/yr in the upper meter. Visual descriptions and Scopix radiographies show that the sediment record is finely laminated except a massive decimetric coarser and darker layer corresponding to a tephra (estimated age 700AD±50). Magnetic susceptibility (confirmed by scopix radiographies) highlights the presence of 8 additional millimetric tephra layers. The biogenic silica content of the sediment is low (mean 5%). Diatom assemblage is dominated by benthic and acidophilous species, with high saprobic values. None marked changes were observed regarding the dynamic of the lake. The high organic matter content (mean 15%) and its high C/N ratio (12.7) throughout the core indicate inputs of allochtonous and terrestrial organic matter. Such parameters present high sediment variability also marked by changes in the chemical composition. The laminations reflect changes in the allochtonous sedimentary inputs, with high terrestrial inputs during wetter conditions in relation with the Westerlies. The sedimentary records of Lago Esponja will be compared with Eastern lacustrine record from the same latitude in order to confirm the climate-driven record. [less ▲]

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See detailChemical and mineralogical proxies of erosion episodes in the dried lake sediments (Amik Lake, Southern Turkey): paleoenvironmental implications
El Ouahabi, Meriam ULg; Hubert, Aurelia ULg; Lebeau, Héléne et al

Poster (2016, April 17)

The Amik Basin in the Eastern Mediterranean region has been continuously occupied since 6000-7000 BC. The landscape has sustained with highly variable anthropic pressure culminating during the Late Roman ... [more ▼]

The Amik Basin in the Eastern Mediterranean region has been continuously occupied since 6000-7000 BC. The landscape has sustained with highly variable anthropic pressure culminating during the Late Roman Period when the Antioch city reached its golden age. The basin also sustained a high seismic activity (M≥7) as it is a releasing step-over along the Dead Sea Fault. The study focuses on the sedimentary record of the Amik Lake occupying the central part of the Basin. Our objective is to constrain major paleo-environmental changes in the area over the last 4000 years and to unravel possible human impacts on the sedimentation. A diverse array of complementary methods was applied on the 6 m long record. High resolution of mineralogical (XRD) and geochemical (XRF) analyses were performed. Quantitative mineralogical phases of sediments by the Rietveld method were computed using Topaz software. The age of the record is constrained combining radionuclide and radiocarbon dating, and checked using the correlation between the earthquake history and rapidly deposited layer identified. A high sedimentation rate of 0.12 cm/yr was inferred at the coring site. The 4000 years old record shows that significant fluctuations of the lake level and the riverine system inflow into the Amik Lake occurred. The Late Bronze lowstand leaded to punctual dryings of the lake at the end of the Bronze/Iron transition marked by the collapse of the Hittite Empire and during the Dark ages. At that time, the riverine was carrying a large terrigenous input linked to strong soil erosion related to deforestation, exploitation of mineral resources and the beginning of upland cultivation. During the Roman Period and in the later periods, upland soils were partly depleted and the riverine system completely transformed by channelization that leaded to a mashification of the Amik Basin. Chemical and mineralogical composition of sediments is quite diversified reflecting the significant geological variation of drainage basins. Abundant calcareous minerals, especially calcite, aragonite, dolomite and small amount of wollastonite characterize the different sedimentary levels recorded in the lake. Levels relatively rich in fluorite, richerite, enstatite, and wollastonite are a result of the erosion of the ophiolitic rocks from the surrounding Amanos Mountains. These levels are interpreted as corresponding to relatively high erosive periods, while more humid periods lead to more intensive weathering and consequently to the dominance of kaolinite, muscovite/illite and talc more advanced in the relative stability scale, indicating a climate with contrasting seasons. During the most recent Period a marked increase in terrigeneous minerals associated with a rise in dolomite indicates ungoing erosion as well as the drying-out of the lake. [less ▲]

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See detailGeoarchaeology of the Ancient Harbour of Utica in a Deltaic Context (2014 and 2015)
Pleuger, Elisa ULg; Gadhoum, Ahmed; Abichou, Hakim et al

Conference (2016, January 28)

Ancient authors mention Utica as a maritime and port city and estimate its origin around the 11th c. BC. However, in the present state of research, no archaeological evidence is earlier than the 9th c. BC ... [more ▼]

Ancient authors mention Utica as a maritime and port city and estimate its origin around the 11th c. BC. However, in the present state of research, no archaeological evidence is earlier than the 9th c. BC, and the location of the Phoenician and Roman port infrastructures remains unknown. Today, the ancient city is located on a promontory in the heart of the Medjerda delta, 10 km inland. Based on this observation, our geoarchaeological research focuses on two main issues: - Was there a marine environment around the promontory of Utica, which could shelter harbour structures? - Why the city, formerly a seaport city, is today located 10 km from the coast? Can the wadi be solely responsible of such an important sediment accumulation in a few millennia? Have any natural or anthropogenic factors influenced this deltaic progradation over the centuries? First results permitted drawing an hypothesis of the coastline during Antiquity to the effect that the Utica promontory was surrounded by the sea in an earlier era. (1) Effectively, the «North compartment» of the delta was covered by the sea at a given time, which will be determined by the next radiocarbon dating. But the sea still brushed the north side of the promontory during the Roman period, as evidenced by the potsherds found in one of the cores. This deep marine bay could be a potential location for harbour infrastructure prior to clogging of the bay by the sediments carried by the wadi. (2) The «corridor» area, materialised by the promontories of Utica and Kalâat el-Andalous, was also invaded by the sea at one time. The many artifacts found in this core attest the occupation of this area, outside of the maximal extension of the ancient city according to A. Lézine. Dating of the marine units in the two cores will bring essential data: * to establish the chronological framework of the retreat of the coastline and of the clogging of the bay; * to understand the passage of the Medjerda into the «North compartment» by the corridor Utica-Kalâat. The geoarchaeological results corroborate ancient sources. Utica was able to welcome important harbour structures, since the presence of a deep marine environment is attested around the promontory, but these remains are probably 5 m deep under the alluvium of the Wadi Medjerda. [less ▲]

Detailed reference viewed: 54 (7 ULg)
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 ▲]

Detailed reference viewed: 68 (3 ULg)
See detailEvolution of the palaeoenvironment of the Medjerda delta (Tunisia) and geoarchaeology of the ancient city of Utica
Pleuger, Elisa ULg; Abichou, Hakim; Gadhoum, Ahmed et al

Conference (2016, January 27)

Phoenician Utica remains today largely unknown, as is its role in the Phoenician expansion in the western Mediterranean. Aristotle and Pliny the Elder mention Utica as a maritime and port city and ... [more ▼]

Phoenician Utica remains today largely unknown, as is its role in the Phoenician expansion in the western Mediterranean. Aristotle and Pliny the Elder mention Utica as a maritime and port city and estimate its origin around the 11th c. BC. However, in the present state of research, no archaeological evidence is earlier than the 9th c. BC, and the location of the Phoenician and Roman port infrastructures remains unknown. Today, the ancient city is located on a promontory in the heart of the Medjerda delta, 10 km inland. This project proposes an interdisciplinary effort to understand the Medjerda delta landscape changes during the Holocene. It starts from an archaeological problem and proposes the contribution of geoarchaeology to the understanding of the relationship between ancient societies and their environment. The fluvial palaeoenvironments and sedimentary processes are studied through the mechanical extraction of cores (15-20 m deep) to reach the early Holocene. Selected sediment samples are then studied in laboratory, using different and complementary approaches. The location of port infrastructures will bring initial answers to the question of the foundation of the city. The study of river palaeoenvironments of the Medjerda delta during the Holocene aim at a better understanding of the nature of the settlement, as well as the function of the city of Utica over time. This study will also assess the impact of the ancient city on the environment and understand how the city adapted to the mobility of this Mediterranean delta. Furthermore, the analysis of sedimentary processes causing the filling of the harbour basin will lead to speculation about the causes of the abandonment of the structures and more generally the decline of the city in favor of Carthage. It will also examine whether natural or anthropogenic factors have influenced this deltaic progradation over the centuries. [less ▲]

Detailed reference viewed: 51 (6 ULg)
See detailLandslides' mechanism and evolution in the western Rwanda
Draidia, Salah ULg; El Ouahabi, Meriam ULg; Dewitte, Olivier et al

Scientific conference (2016, January 27)

Landslides' mechanism and evolution in the western Rwanda Salah DRAIDIA1,*, Meriam EL OUAHABI1, Olivier DEWITTE2, Nathalie Fagel1, Hans Balder HAVENITH1 1 Institution 1 University of Liège Department of ... [more ▼]

Landslides' mechanism and evolution in the western Rwanda Salah DRAIDIA1,*, Meriam EL OUAHABI1, Olivier DEWITTE2, Nathalie Fagel1, Hans Balder HAVENITH1 1 Institution 1 University of Liège Department of Geology Street, n° 4000 Liège Belgium 2 Institution 2 Royal Museum of Central Africa Department of Geomogy Tervuren Belgium *Corresponding author: sdraidia@gmail.com, Département de Géologie, Quartier Agora, Allée du six Août, 14, B- 4000 LIEGE (Sart Tilman) Tel +32 0497351617 Keywords: mass movement, landslides, landscape evolution, geohazard,. Abstract The mass movement, and especially the instability of the soil and rocks, play a significant role in the changing aspect and the evolution of the landscape worldwide and particularly in tropical region. In Central Africa the landslides and others kind of instabilities are very frequent, important and represent a real threat for both population and economy. The case of Rwanda is remarkable, this country which is known as the country of thousand hills, is rich of various and very complex morphology caracterized by very steep slopes crossed by a dense network of watercourse, powered by a considerable amount of precipitation distributed in two wet seasons. The growing economy of the country brings a lot of project of infrastructures and mines and quarries exploitation (embankments and cuttings) which have a strong impact on the triggering of huge instabilities and so the modification of landscape. These instabilities and the intense activity of the rivers and streams could be considered as the engine who control the shaping and the remodeling of the landform. To understand the evolution process of these instabilities, and then the landscape change we started by the mapping of the instabilities using satellite images and then we went on the field to validate the inventory to identify the morphological aspect of the terrain, to refine our knowledge of the geological nature of the materials by sedimentological analyses on selected samples, and of course to try to better know the impact of the rock's weathering process leading to the constant modification of the landform. The computer-based quantitative analyses using GIS's data processing, were carried out to help to understand the distribution of the instabilities and the geomorphological phenomena observed to better connect and explain the whole information collected. The aim of the study is to bring in more than the mapping of instabilities a response about the process and the evolution of the instabilities and the factors impacting the phenomenon. [less ▲]

Detailed reference viewed: 84 (5 ULg)