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See detailSuitability of soils and river deposits from Marrakech for the manufacturing of earthenware
El Boudour El Idrissi, Hicham ULg; Daoudi, Lahcen; El Ouahabi, Meriam ULg et al

in Applied Clay Science (in press)

This paper investigates the suitability of clayey materials originating from semi-arid soil and river sediments, used by potters in the Agafay region for the manufacture of ceramic products. The clay ... [more ▼]

This paper investigates the suitability of clayey materials originating from semi-arid soil and river sediments, used by potters in the Agafay region for the manufacture of ceramic products. The clay samples were subjected to particle-size analysis, X-ray diffraction and X-ray fluorescence to investigate their physical, mineralogical and chemical characteristics respectively. The physical behaviour of the intermediate products was studied at the shaping and drying stages of the ceramics manufacturing process through the Atterberg limits and the plot of the Bigot curve respectively. The final product characteristics were determined through porosity tests, flexural and compressive strengths tests. Based on results obtained, the raw materials turn out to be suitable characteristics for the manufacture of earthenware products. The application of the suggested recommendations is worthy for the improvement of the products based on such raw materials. [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 ▲]

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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 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 ▲]

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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 ▲]

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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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See detailDistribution of heavy and clay minerals in coastal sediment of jijel, East of Algeria: indicators of sediment sources and transport and deposition environments
KERMANI, S.; BOUTIBA, M.; BOUTALEB, A. et al

in Arabian Journal of Geosciences (2016)

Detailed reference viewed: 109 (29 ULg)
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See detailTransformed mineral phases during clay ceramic firing
El Ouahabi, Meriam ULg; Daoudi, Lachen; Hatert, Frédéric ULg et al

in Clays and Clay Minerals (2015), 62(6), 470478

Ceramic clays are one of the most complicated ceramic systems because of the very complex relationship between the behavior of minerals during the ceramic processing and the transformations during heating ... [more ▼]

Ceramic clays are one of the most complicated ceramic systems because of the very complex relationship between the behavior of minerals during the ceramic processing and the transformations during heating. A major challenge is to predict the phase transformations in clay ceramics. The aims are to establish reference data of ceramics products that can be formed based on the mineralogical composition of the local raw materials. These data, in turn, can be compared with the archaeological ceramics in order to study their origins. The mineralogical compositions and transformations during the firing (550 to 1100ºC under oxidizing conditions) of seven clayey materials sampled from the main clay deposits of Northern Morocco were evaluated by X-ray powder diffraction. Two groups of clays were evidenced according to the type of neoformed high-temperature minerals: non-calcareous clays and calcareous clays. For the non-calcareous raw materials, spinel is produced at 950°C. Cristobalite and mullite were formed above 1000ºC from clays that contain illite, kaolinite and chlorite. In clays containing vermiculite and high amount of chlorite, hematite was formed from 950°C. Firing of calcareous clays at temperatures > 950ºC yielded Ca-silicates (diopside, gehlenite and wollastonite), spinel, cristobalite, hematite and feldspars. Mullite may also form in the calcareous clay products, when the carbonates content exceeds 10%. [less ▲]

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See detailPALEO-DELTA: Palaeoenvironment and geoarchaeology of the Medjerda delta (Tunisia)
Pleuger, Elisa ULg; Abichou, Hakim; Gadhoum, Ahmed et al

Poster (2015, October)

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 ▲]

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See detailWhere is the ancient harbour of Utica ? Geoarchaeology and palaeoenvironment of the Medjerda delta (Tunisia)
Pleuger, Elisa ULg; Abichou, Hakim; Gadhoum, Ahmed et al

Poster (2015, October)

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. 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. First results permitted to draw an hypothesis of the coastline during Antiquity and to bring out the evidence of an intense sedimentation event post 10th c. BC. 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 ▲]

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See detailAtmospheric metal pollution over the last 250 years inferred from speleothem geochemistry
Allan, Mohammed ULg; Fagel, Nathalie ULg; Verheyden, Sophie

Conference (2015, August 17)

Lead concentrations and isotope ratios from two speleothems from the Han-sur-Lesse cave in southern Belgium were measured in order to study the ability of speleothems to act as archives of atmospheric ... [more ▼]

Lead concentrations and isotope ratios from two speleothems from the Han-sur-Lesse cave in southern Belgium were measured in order to study the ability of speleothems to act as archives of atmospheric pollution. To address this aim we analyzed trace elemental Al and Pb compositions by LA-ICP-MS and ICP-MS as well as Pb isotopes by MC-ICP-MS. The results help to identify three Pb-enriched intervals: from 1880 to 1905 AD, from 1945 to 1965 AD, and from 1975 to 1990 AD. The speleothem record is consistent with the evolution of atmospheric pollution in Belgium. Lead isotope ratios confirm that coal and gasoline combustion, combined with regional metallurgical activities, were the predominant Pb pollution sources in the stalagmites during the last 250 years. This research underscores the importance of speleothems as a valuable tool for the discrimination between anthropogenic and natural lead contributions in the environment and consequently for quantifying the anthropogenic contribution or determining natural background values in continental settings. [less ▲]

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See detailLand erosion and associated evolution of clay minerals assemblages in Mediterranean region (Southern Turkey): Amik Lake
El Ouahabi, Meriam ULg; Hubert, Aurelia ULg; Lebeau, Helene et al

Poster (2015, July)

Under Mediterranean context, continuous human occupation is attested in the Amik Basin (southern Turkey) since 6000-7000 BC. The Basin also is crossed by The Dead Sea Fault (DSF), a major neotectonic ... [more ▼]

Under Mediterranean context, continuous human occupation is attested in the Amik Basin (southern Turkey) since 6000-7000 BC. The Basin also is crossed by The Dead Sea Fault (DSF), a major neotectonic structure in the Middle East extending from the Red Sea in the south to the East Anatolian Fault Zone in the north. The study focuses on the mineralogy and clay mineralogy record of the Amik Lake occupying the central part of the Basin. Our objective is to constrain major mineralogical and clay minerals evolution in the area over the last 4000 years and assess changes that would be related to the different land uses during the different Bronze, Roman, Ottoman and Modern civilizations. Sediments were collected at 1 to 2 cm intervals in core sediments up to a depth of 6 meters in the clay deposits. Geochemistry (XRF), mineralogy (XRD) and clay mineralogy are applied to study the sediment records. The age of the record is constrained combining radionuclide and radiocarbon dating. Chemical and mineralogical composition of sediments is quite diversified reflecting the significant geological variation of drainage basins. Abundant mixed-layer and partly disordered minerals characterize the different sedimentary levels recorded in those cores. Levels relatively rich in chlorite, illite and quartz are interpreted as corresponding to relatively dry periods, while more humid periods lead to more intensive weathering and consequently to the dominance of clay minerals more advanced in the relative stability scale, such as kaolinite. Smectite is taken to indicate a climate with contrasting seasons and a pronounced dry season. The sedimentary record clearly shows two periods indicating strong soil erosion in the Lake catchment. The most recent erosion phase is modern. The oldest one would have started during the late Bronze period and lasted until the late Roman Period. The first and older period is attributed to a strong aggradation linked to major increase in erosion. Our study shows that this episode has specific characteristics: mixed-layer clay mineral, high percent in Ni, Cr and Mg coupled with significant amount of organic matter of terrestrial origin. Ni and Mg most probably come from the Amanos Mountains an ophiolitic belt indicating an intensive upland cultivation and possible exploitation of its mineral resource. The second period is attributed to the modern period. The signature of the increase in erosion is different, because most of the soil cover has already been eroded. Only a patchy thin and unmature soil cover exists since the Late Roman time. Erosion is associated with a marked increase of smectite-illite interstratified clay, goethite and hematite found in deep soil horizons. Moreover, a marked increase in Cr is showed and is probably related to an enhanced exploitation of its mineral resource and to a renew land exploitation of the Amanos Mountain Range. [less ▲]

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See detailLANDSLIDES IN CENTRAL AFRICA: FROM DEFORMATION MECHANISMS TO EVOLUTION PROCESSES – CASES STUDIES FROM RWANDA AND BURUNDI
Draidia, Salah ULg; Ndahimana, Hamuli; Habimana, Christophe et al

Scientific conference (2015, July)

Detailed reference viewed: 38 (9 ULg)
Peer Reviewed
See detailIdentification of the main parameters controlling the plasticity of ceramic pastes: The case study of the Marrakech region (Morocco)
El Boudour El Idrissi, Hicham ULg; Daoudi, Lahcen; Fontaine, François ULg et al

Poster (2015, June 07)

Numerous traditional ceramic workshops occur within a range of 10 to 80 km around the city of Marrakech. Our study aims to identify the main parameters controlling the plasticity of pastes used by the ... [more ▼]

Numerous traditional ceramic workshops occur within a range of 10 to 80 km around the city of Marrakech. Our study aims to identify the main parameters controlling the plasticity of pastes used by the artisans. To reach this goal, we characterize by X-ray diffraction, granulometry and plasticity index (PI) the local raw clayey material. The investigation of 26 whole pastes shows the dominance of quartz (20 to 50%) and clay minerals (25 to 60%) with K-feldspar (2 to 17%), plagioclase (2 to 25%), calcite (0 to 18%), dolomite (0 to 15%), goethite (0 to7%) and trace of hematite and anhydrite (< 3%). Amphibole occurs in trace (< 5%) but only in some samples. The clay minerals are diversified, including illite (10 to 40%), kaolinite (2 to 15%), mixed-layer (ML) (0 to 10%), smectite, vermiculite and chlorite (0 to 5%), and pyrophyllite-talc association (0 to 8%). Sepiolite (12%) is only present in one paste. The grain size is made by variable proportions of sand (5 to 65%), silt (12 to 53%) and clayey fraction (18 to 66%). The Plasticity index (PI) indicates the presence of two principals groups of pastes. (1) The first group is characterized by PI values ranging between 15 to 18. Their moderate plasticity behavior is related either to the low rate of clayey fraction and/or to the absence of plastic clays like smectites and mixed layer with smectitic sheets. (2) The PI of second group ranges between 20 to 32. The high plasticity values are influenced by the presence of specific clayey minerals like talc-pyrophyllite or sepiolite, or by the high content of smectite plus smectitic mixed-layers within the clayey (< 2 micron) fraction. Only one sample without any of these plastic minerals but with a high content of clayey fraction is characterized by a high PI value (24). We concluded that the workability of ceramic paste in Marrakech region is controlled by a combination of factors, dominated by the grain size distribution and the content in plastic clay minerals within the fine fraction. [less ▲]

Detailed reference viewed: 36 (11 ULg)