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 detailHigh-resolution reconstruction of 8.2 ka event recorded in Belgian Holocene speleothems
Allan, Mohammed ULg; verhyden, sophie; Fagel, Nathalie ULg

Scientific conference (2017, August 24)

Two abrupt shifts in d18O and trace element contents of a stalagmite from the northwestern European continent (southern Belgium) suggest that two cold anomalies occurred beginning at 8.4±0.04 and ending ... [more ▼]

Two abrupt shifts in d18O and trace element contents of a stalagmite from the northwestern European continent (southern Belgium) suggest that two cold anomalies occurred beginning at 8.4±0.04 and ending at 8.15±0.03, possibly reflecting climatic effects associated with the 8.2 ka event. The younger of the two anomalies lasted about 30 years, from 8.18 to 8.15±0.03 ka, with a maximum d18O amplitude of 1.4‰. Trace element (Sr, Ba and Mg) peaks coincide with this second drop of d18O. The anomaly initiation is marked by Sr, Ba and Mg concentration peaks suggesting drier conditions during the coldest years, consistent with previous research in the North Atlantic. The earlier anomaly in trace element, d18O records is associated with generally cold but wet conditions at 8.4 ka, lasted 50 years, and ended abruptly. The interval from 8.4 ka to 8.15 ka was less favorable for speleothem deposition, with denser speleothem calcite deposition and lower growth rate, consistent with a cold, dry climate. The clear recovery in both temperature and rainfall between after both anomalies (8.2 and 8.4 ka), suggests that these anomalies are distinct, and may represent two episodes of AMOC weaking related to the drainage of proglacial lakes Agassiz and Ojibway. [less ▲]

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See detailConstruction of high-resolution trace element time-series in Belgian speleothems by LA-ICP-MS
Allan, Mohammed ULg; verheyden, sophie; crucifix, michel et al

Conference (2017, August 17)

Speleothems, presented in Belgium, are now regarded as valuable archive of paelenvirenmental variations on the continents, offering a number of advantages relative to other continental climate proxy ... [more ▼]

Speleothems, presented in Belgium, are now regarded as valuable archive of paelenvirenmental variations on the continents, offering a number of advantages relative to other continental climate proxy recorders such as lake sediments. They are reliable continental archives of high interest due to their dating possibilities and their possibility to preserve multi-proxy records of environmental and climatic dynamics. Establishing high-resolution trace element time series in speleothems requires analytical techniques capable of representative sampling at sub-annual spatial resolution (on order of 22 µm in this study). In the Belgian Pere Noel cave (PN), high spatial resolution measurements of trace elements (e.g., Mg, Sr, Ba) were realized by using LA-ICP-MS and compared with results from lower resolution techniques (ICP-MS). The results from both techniques have been analysed in order to assess the capability of each technique to reconstruct climate changes at high resolution from PN stalagmite. Results showed that LA-ICP-MS technique allows a rapid analysis of multiple elemental concentrations, and uses minimal sample volume allowing for replicate sampling and availability of almost the entire original sample for other analyses. [less ▲]

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See detailDoes Belgian Holocene speleothem record solar forcing and cold events?
Allan, Mohammed ULg; Deliège, Adrien ULg; Nicolay, Samuel ULg et al

in Climate of the Past Discussions (2017)

We present a decadal-centennial scale Holocene climate record based on trace elements contents from a 65 cm stalagmite (Père Noël) from Belgian Père Noël cave. Père Noël (PN) stalagmite covers the last 12 ... [more ▼]

We present a decadal-centennial scale Holocene climate record based on trace elements contents from a 65 cm stalagmite (Père Noël) from Belgian Père Noël cave. Père Noël (PN) stalagmite covers the last 12.7 ka according to U/Th dating. High spatial resolution measurements of trace elements (Sr, Ba, Mg and Al) were done by Laser-Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Trace elements profiles were interpreted as environmental and climate changes in the Han-sur-Lesse region. Power spectrum estimators and continuous wavelet transform were applied on trace elements time series to detect any statistically significant periodicities in the PN stalagmite. Spectral analyses reveal decadal to millennial periodicities (i.e., 68–75, 133–136, 198–209, 291–358, 404–602, 912–1029 and 2365–2670 yr) in the speleothem record. Results were compared to reconstructed sunspot number data to determine whether solar signal is presents in PN speleothem. The occurrence of significant solar periodicities (i.e., cycles of Gleissberg, de Vries, unnamed 500 years, Eddy and Hallstat) supports for an impact of solar forcing on PN speleothem trace elements contents. Moreover, several intervals of significant rapid climate change were detected during the Holocene at 10.3, 9.3–9.5, around 8.2, 6.4–6.2, 4.7–4.5, and around 2.7 ka BP. Those intervals are similar to the cold events evidenced in different natural paleoclimate archivers, suggesting common climate forcing mechanisms related to changes in solar irradiance. [less ▲]

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See detailDoes Belgian Holocene speleothem record solar forcing and cold events?
Allan, Mohammed ULg; Deliège, Adrien ULg; Nicolay, Samuel ULg et al

in Climate of the Past Discussions (2017)

We present a decadal-centennial scale Holocene climate record based on trace elements contents from a 65 cm stalagmite (Père Noël) from Belgian Père Noël cave. Père Noël (PN) stalagmite covers the last 12 ... [more ▼]

We present a decadal-centennial scale Holocene climate record based on trace elements contents from a 65 cm stalagmite (Père Noël) from Belgian Père Noël cave. Père Noël (PN) stalagmite covers the last 12.7 ka according to U/Th dating. High spatial resolution measurements of trace elements (Sr, Ba, Mg and Al) were done by Laser-Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Trace elements profiles were interpreted as environmental and climate changes in the Han-sur-Lesse region. Power spectrum estimators and continuous wavelet transform were applied on trace elements time series to detect any statistically significant periodicities in the PN stalagmite. Spectral analyses reveal decadal to millennial periodicities (i.e., 68–75, 133–136, 198–209, 291–358, 404–602, 912–1029 and 2365–2670 yr) in the speleothem record. Results were compared to reconstructed sunspot number data to determine whether solar signal is presents in PN speleothem. The occurrence of significant solar periodicities (i.e., cycles of Gleissberg, de Vries, unnamed 500 years, Eddy and Hallstat) supports for an impact of solar forcing on PN speleothem trace elements contents. Moreover, several intervals of significant rapid climate change were detected during the Holocene at 10.3, 9.3–9.5, around 8.2, 6.4–6.2, 4.7–4.5, and around 2.7 ka BP. Those intervals are similar to the cold events evidenced in different natural paleoclimate archivers, suggesting common climate forcing mechanisms related to changes in solar irradiance. [less ▲]

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See detailDoes Belgian Holocene speleothem record solar forcing and cold events?
Allan, Mohammed ULg; Deliège, Adrien ULg; Nicolay, Samuel ULg et al

in Climate of the Past Discussions (2017)

We present a decadal-centennial scale Holocene climate record based on trace elements contents from a 65 cm stalagmite (Père Noël) from Belgian Père Noël cave. Père Noël (PN) stalagmite covers the last 12 ... [more ▼]

We present a decadal-centennial scale Holocene climate record based on trace elements contents from a 65 cm stalagmite (Père Noël) from Belgian Père Noël cave. Père Noël (PN) stalagmite covers the last 12.7 ka according to U/Th dating. High spatial resolution measurements of trace elements (Sr, Ba, Mg and Al) were done by Laser-Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Trace elements profiles were interpreted as environmental and climate changes in the Han-sur-Lesse region. Power spectrum estimators and continuous wavelet transform were applied on trace elements time series to detect any statistically significant periodicities in the PN stalagmite. Spectral analyses reveal decadal to millennial periodicities (i.e., 68–75, 133–136, 198–209, 291–358, 404–602, 912–1029 and 2365–2670 yr) in the speleothem record. Results were compared to reconstructed sunspot number data to determine whether solar signal is presents in PN speleothem. The occurrence of significant solar periodicities (i.e., cycles of Gleissberg, de Vries, unnamed 500 years, Eddy and Hallstat) supports for an impact of solar forcing on PN speleothem trace elements contents. Moreover, several intervals of significant rapid climate change were detected during the Holocene at 10.3, 9.3–9.5, around 8.2, 6.4–6.2, 4.7–4.5, and around 2.7 ka BP. Those intervals are similar to the cold events evidenced in different natural paleoclimate archivers, suggesting common climate forcing mechanisms related to changes in solar irradiance. [less ▲]

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See detailDoes Belgian Holocene speleothem record solar forcing and cold events?
Allan, Mohammed ULg; Deliège, Adrien ULg; Nicolay, Samuel ULg et al

in Climate of the Past Discussions (2017)

We present a decadal-centennial scale Holocene climate record based on trace elements contents from a 65 cm stalagmite (Père Noël) from Belgian Père Noël cave. Père Noël (PN) stalagmite covers the last 12 ... [more ▼]

We present a decadal-centennial scale Holocene climate record based on trace elements contents from a 65 cm stalagmite (Père Noël) from Belgian Père Noël cave. Père Noël (PN) stalagmite covers the last 12.7 ka according to U/Th dating. High spatial resolution measurements of trace elements (Sr, Ba, Mg and Al) were done by Laser-Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Trace elements profiles were interpreted as environmental and climate changes in the Han-sur-Lesse region. Power spectrum estimators and continuous wavelet transform were applied on trace elements time series to detect any statistically significant periodicities in the PN stalagmite. Spectral analyses reveal decadal to millennial periodicities (i.e., 68–75, 133–136, 198–209, 291–358, 404–602, 912–1029 and 2365–2670 yr) in the speleothem record. Results were compared to reconstructed sunspot number data to determine whether solar signal is presents in PN speleothem. The occurrence of significant solar periodicities (i.e., cycles of Gleissberg, de Vries, unnamed 500 years, Eddy and Hallstat) supports for an impact of solar forcing on PN speleothem trace elements contents. Moreover, several intervals of significant rapid climate change were detected during the Holocene at 10.3, 9.3–9.5, around 8.2, 6.4–6.2, 4.7–4.5, and around 2.7 ka BP. Those intervals are similar to the cold events evidenced in different natural paleoclimate archivers, suggesting common climate forcing mechanisms related to changes in solar irradiance. [less ▲]

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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 detailLacustrine clay mineral assemblages as a proxy for land-use and climate changes over the last 4 kyr: The Amik Lake
El Ouahabi, Meriam ULg; Hubert, Aurelia ULg; Allan, Mohammed ULg et al

Poster (2017, May 10)

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 detailBenthic hypoxia and early diagenesis in the Black Sea shelf sediments
Plante, Audrey ULg; Roevros, Nathalie; Capet, Arthur ULg et al

Poster (2017, April)

Marine waters of semi-enclosed seas are affected by a major environmental issue which is oxygen depletion in bottom waters. Deoxygenation is one of the most widespread man-induced consequences which can ... [more ▼]

Marine waters of semi-enclosed seas are affected by a major environmental issue which is oxygen depletion in bottom waters. Deoxygenation is one of the most widespread man-induced consequences which can be catastrophic for living species. Between 1970 and 1990, the benthic compartment of the Black Sea underwent modifications due to the occurrence and increase of hypoxia. Indeed, these changes might cause a deterioration of the structure and functioning of the ecosystems. Nowadays, some regions, such as the north-western shelf, are still affected seasonally by this phenomenon.Within the framework of the BENTHOX project, a biogeochemical study focusing on the early diagenesis is conducted in the Black Sea. It aims (1) to obtain a better understanding of the impact of benthic hypoxia on the diagenetic pathways, (2) to contribute to a new dataset of biogeochemical measurements in the sediments including porewaters. During a cruise (Emblas II – May 2016), on board the RV Mare Nigrum, sediment cores were taken at 4 stations on the Ukrainian shelf. Porewaters were extracted on board the ship using Rhizon technique under N2 atmosphere and will be analyzed for dissolved nutrients and major ions. In addition, sediments were sliced and will be determined for major solid phases and trace element contents. A multi-proxies (biological, sedimentological, mineralogical and geochemical) approach will be used to identify the hypoxic events and to reconstruct the history of bottom hypoxia. The results obtained will be presented and discussed with emphasis on the first outcomes and the major biogeochemical processes involved in the early diagenesis. [less ▲]

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See detailTectonic, human and climate signal over the last 4000 years in the Lake Amik record (southern Turkey)
El Ouahabi, Meriam ULg; Hubert, Aurelia ULg; Vander Auwera, Jacqueline ULg et al

Poster (2017, April)

This study investigates the upper sediments infilling the central part of the Amik Basin in Southern Turkey. The Amik Basin is located in a tectonically active area: it is crossed by the Dead Sea Fault, a ... [more ▼]

This study investigates the upper sediments infilling the central part of the Amik Basin in Southern Turkey. The Amik Basin is located in a tectonically active area: it is crossed by the Dead Sea Fault, 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. Continuous human occupation is attested since 6000-7000 BC in the Amik Basin. The study focuses on the sedimentary record of the Lake Amik occupying the central part of the Basin. Our objective is to constrain major paleo-environmental changes over the last 4000 years. The lake has been drained and progressively dried up since the mid-50s. The absence of water column during the summer season allows to collect lacustrine samples along a 5 meter depth trench with a sampling resolution of 1 to 2 cm. Diverse complementary methods were applied to characterize the sedimentary record: i.e. magnetic susceptibility, grain size, organic and inorganic matter by loss-of-ignition, mineralogy by X-ray diffraction and core scanner X-ray fluorescence (XRF) geochemistry. The age of the record is constrained combining radionuclide and radiocarbon datings. Structural disturbances observed in the lacustrine sediments record are linked with major historical earthquakes from the 6th to the 9th century AD due to the Hasipasa Fault rupture. In addition to the tectonic influence, the sedimentary record clearly shows two periods indicating strong soil erosion in the lake catchment: (1) the most recent erosion phase occurs over the Roman period to Present; (2) the oldest one would have occurred during the Late Bronze period. Such changes are most probably related to change in land use. In term of climate influences, the mineralogical and geochemical results allow to evidence variations in chemical weathering conditions in the watershed and lake water level fluctuations, respectively. The clay mineral assemblages attest for significant pedogenesis transformations, especially during the Islamic/Ottoman period. Based on XRF results, an increase in potassium is attributed to a lake development phase during a wet phase An overflow of the Orontes River would be responsible for clay deposition. By contrast, increased calcium and strontium rather correspond to a low lacustrine level and a drier period. The Bronze and Iron/Hellenistic periods are both characterized by low lake level with limited contribution from the watershed. To conclude, our multiproxy study of the Lake Amik allows to decipher between tectonic, human and climate influences over the last 4000 years. Further step would be to compare the Amik record with other regional archives to evidence local and regional events. [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 (2017), 1/15

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 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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