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See detailLitholog generation with the StratigrapheR package and signal decomposition for cyclostratigraphic purposes
Wouters, Sébastien ULiege; Da Silva, Anne-Christine ULiege; Crucifix, Michel et al

Conference (2019, April 10)

To establish an astronomical time scale, it is useful to perform a visual inspection of the lithological evolution, together with proxies record. It allows to have a clear understanding of the expression ... [more ▼]

To establish an astronomical time scale, it is useful to perform a visual inspection of the lithological evolution, together with proxies record. It allows to have a clear understanding of the expression of Milankovitch cyclicity. However, performing such an inspection can be challenging due to the large amount of data and high spatial resolution required to perform a sound cyclostratigraphic analysis. To address this problem we present the StratigrapheR package in the free software environment R (https://CRAN.R-project.org/package=StratigrapheR). This package is designed to generate lithologs and to deal with stratigraphical information. StratigrapheR takes advantage of the repetitive nature of sections used for cyclostratigraphic purposes to automate as much as possible the litholog generation while still allowing the visualisation of discrepancies (e.g. lateral variations of thickness and irregular stratification boundaries) and of any particular features (e.g. fossil content, sedimentary structures, stratigraphical intervals, etc.). The package furthermore allows to import vector graphics as SVG files, to export the lithologs in PDF and SVG form, to manipulate stratigraphic interval data and to visualise oriented palaeomagnetic data. The lithologs made in StratigrapheR can be plotted at high resolution directly along the results of time series filtering and/or decomposition methods. This is particularly useful for high-frequency components inspection. Empirical Mode Decomposition (EMD) in particular can be used for visual inspection. It allows to compute different components -also called modes- by iteratively subtracting from the signal the mean envelope curves, defined by local minima and maxima. In the isolated modes, each contiguous local extrema are separated by a zero-crossing. This property furthermore allows the determination of instantaneous frequency and amplitude, using for instance the Hilbert transform. EMD typically decomposes standard cyclostratigraphic time series in maximum 15 modes, which allows all the instantaneous ratios of the modes frequencies - taken two by two- to be calculated in a realistic computational time. These instantaneous ratios of frequencies can then be used to find the signature of Milankovitch cycles by identifying relatively higher ratios distributions at values characteristic of the orbital cycles. Specific ratios intervals can then be isolated and linked back to the parts of the signal that are at their source. [less ▲]

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See detailSilurian Succession from North Africa (Algeria) – A Review for a New Era of Hydrocarbon Exploration
Djouder, Hocine ULiege; Uysal, Tonguç; Boulvain, Frédéric ULiege et al

Conference (2018, December 07)

The diagenetic grade and thermal history of the widespread graptolitic Silurian Oued Imihrou black shales (Llandoverian in age) and the overlying sandstone levels of the Atafaïtafa Formation (late ... [more ▼]

The diagenetic grade and thermal history of the widespread graptolitic Silurian Oued Imihrou black shales (Llandoverian in age) and the overlying sandstone levels of the Atafaïtafa Formation (late Llandoverian to Wenlockian) from the Tassili n'Ajjer plateau have been investigated by integrating a variety datasets, such as illite crystallinity, graptolite-derived organic matter reflectance, source-rock maturity and illite K–Ar ages. Combination of X-ray diffraction and petrographic examinations allowed to confirm the occurrence of three distinct minerals of authigenic origin, i.e. kaolinite, illite, and iron-rich chlorite, within the Silurian succession. These clay minerals, as well as pyrite and quartz overgrowths, were neoformed at different times during diagenetic-to-hydrothermal conditions and conversion-precipitation reactions. Furthermore, formation processes of these minerals are found to be broadly controlled by the stratigraphical level, lithology of the host rocks and the paleogeographical location of the studied outcrop sections from the eastern- and western-Tassili n'Ajjer plateau (Djouder et al., 2018). The illite crystallinity (i.e. Crystallinity index standards or CIS-calibrated IC values range between 1.58 to 0.38 Δ°2θ), paleotemperature estimates (~113–190°C) and graptolite reflectance (vitrinite reflectance equivalent, 0.65–1.5% VReqv) correspond to low grade diagenesis/anchi-metamorphic illite crystallization conditions and the oil-to-wet gas hydrocarbon generation zone. A paleothermal gradient towards the West is clearly present. This higher thermal maturity of the most western part of the Tassili (Tmax=466–483°C) is intimately linked to the migration of hot fluids, notably along N-S lineaments mega-shear zones in the Hoggar Shield. The latter were repeatedly reactivated during the Phanerozoic orogenies and rifting phases. K−Ar dating results indicate at least two generations of authigenic micrometric illite crystals, which are interpreted to reflect the timing of fluid flow events in association with fault reactivations within the Tassili n'Ajjer plateau at the northern Hoggar Shield. The older illite of 335 ± 8 Ma is consistent with the timing of the early Hercynian tectono-thermal activity in the region, accompanied probably by the first hydrocarbon generation, i.e. Carboniferous age ‘Visean’. While, the younger illite precipitations at 238 ± 11 Ma (Mid–Upper Triassic) and at 204 ± 6 to 179 ± 4 Ma (Triassic–Jurassic transition) can be attributed to high temperature fluid flow and kerogen maturation of the Early Silurian black shales, following Tethys rifting and the later development of the Central Atlantic Magmatic Province, respectively. [less ▲]

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See detailThe Silurian graptolitic black shales of the Tassili n'Ajjer plateau (Algeria): Thermal maturity evolution and origin-timing of late diagenetic illite
Djouder, Hocine ULiege; Uysal, Tonguç; Bourdet, Julien et al

Conference (2018, September 14)

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See detailWeathering pattern of Messinian lithothamnium limestones: implication about paleoclimatic conditions
Moulana, Meriem Lina ULiege; El Ouahabi, Meriam ULiege; Boulvain, Frédéric ULiege et al

Conference (2018, September 14)

Limestones are prevalent in Algeria. These formations since their deposition have been affected by a range of weathering, dissolution and recrystallization processes dependant of the paleoclimatic ... [more ▼]

Limestones are prevalent in Algeria. These formations since their deposition have been affected by a range of weathering, dissolution and recrystallization processes dependant of the paleoclimatic conditions they sustained. These transformations also affect the potential hazard that these karstic terrains represent. We focus here on the Boukadir Region situated at the foot of the Ouarsenis Mountain (Fig. 1). The region comprises the Ouarsenis northern piedmont composed of ~15o north dipping lithothamnium limestones of the Messinian period that rest unconformably upon blue marls of the upper Miocene, and to the south the E-W striking lower Chlef Basin filled by Plio-Quaternary sediments and flooded by the Chlef River. The lithothamnium carbonates rocks form a major deep aquifer in the Basin. The Basin is crossed along its southern edge by the Relizane strike-slip fault. In June 1988, there was a large collapse sinkhole of 60 m in diameter and 35 m of deep that occurred along the national road RN4 near the southern edge of the basin (LCTP, 1989). Drilling shows that sinkhole can be associated to lithothamnium limestones that were covered by more than 61 m of sediments at that location. No other sinkhole formed since this accident. In this study we investigate the weathering pattern of the lithothamnium limestones to unravel the likelihood of formation of large sinkholes in this formation. Boreholes and quarries show that the Messinian Calcareous limestones of the Boukadir region are deeply weathered and partly recrystallized calcareous rocks; the weathering affects its entire thickness reaching a maximum of 200 m. This weathering pattern is not visible a few kilometres more to the east, in limestones having a similar origin. To unravel the specific paleoclimatic conditions that these limestones sustained, we combine field work and on selected samples, petrographic thin section and mineralogical (XRD) analysis and SEM observations. Field work in quarries and in the wadi shows that the lithothamnium limestones are composed of altering sandstone rich beds with a calcareous cement and bioconstructions rich beds. .. [less ▲]

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See detailProgressive increase in organic-matter burial and preservation from the “Weissert” event to the Faraoni event in Umbria-Marche (central Italy)
Wouters, Sébastien ULiege; Schnyder, Johann; Satolli, Sara et al

Conference (2018, September 13)

The Cretaceous experienced several Oceanic Anoxic Events (or OAEs). Anoxia in these events is indicated by deposits of black shales, enriched in organic matter (OM) compared to the layers below and above ... [more ▼]

The Cretaceous experienced several Oceanic Anoxic Events (or OAEs). Anoxia in these events is indicated by deposits of black shales, enriched in organic matter (OM) compared to the layers below and above, strong carbon isotope perturbations, often with a negative excursion at the onset of the OAEs followed by a positive excursion, and concentration of redox-sensitive trace-elements (RSTE) (Baudin & Riquier 2014). Considered to be the earliest Cretaceous OAE (Baudin & Riquier, 2014), the Faraoni level is a short event first defined in the late Hauterivian sections of the Umbria-Marche Apennines (Cecca et al. 1994). It presents black shales enriched in OM with high concentrations of RSTE but lacks an important positive δ13C excursion (Baudin & Riquier, 2014). This event follows the “Weissert” event, a ca. 2.3 million year carbon isotope perturbation event taking place during the late Valanginian-early Hauterivian (Sprovieri et al. 2006). This latter event is not considered to be an OAE, as anoxia indicators such as RSTE high concentrations or OM-rich layers are not observed at least in the western Tethys (Westermann et al. 2010). In order to link those two seemingly opposite events, sections of Late Valanginian to Early Barremian age were studied in the Umbria-Marche Apennines, Italy. Lesser magnitude black shales preceding the Faraoni level were identified. They were correlated in two sections using magnetostratigraphy (Fig. 1). Rock-Eval and palynofacies analyses reveal that they are part of a longer-term trend of increased organic matter preservation and burial. In the black shales this is hinted by a progressive increase of total organic carbon (TOC) content, of the hydrogen index (HI), and by increasingly better preserved amorphous organic matter (AOM) towards the Faraoni level (Fig.1). This increase starts in the upper part of the M5n magnetochron. This is coeval with an increase in mercury concentration interpreted to be due to volcanic activity that was measured among others in the Bosso section (Charbonnier et al., 2018). Palaeoenvironmental differences between the Bosso and Frontone sections are shown by differences in palynomorphs and in organic matter preservation, and by the presence of slumps found in Frontone only. [less ▲]

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See detailThe Hondelange Formation and the sequence stratigraphic model of Belgian Lorraine
Boulvain, Frédéric ULiege; Belanger, Isabelle

in Geologica Belgica (2018), 21(1-2), 59-71

A detailed survey of the Sinemurian-Pliensbachian Hondelange Formation in southern Belgium led to propose a new lithostratigraphic status for this unit. Important lateral variations together with a 10° ... [more ▼]

A detailed survey of the Sinemurian-Pliensbachian Hondelange Formation in southern Belgium led to propose a new lithostratigraphic status for this unit. Important lateral variations together with a 10° angular unconformity with respect to underlying formations suggest that the Hondelange Formation is a prominent element of the transgressive prism in Belgian Lorraine. This study also offers a sequence stratigraphic model for this area with precise description and location of transgressive and maximum flooding surfaces. These results are compared with previous models. A comparison of the magnetic susceptibility data (MS) with sequence stratigraphic units shows that no special effect of the system tract nature is observed. Depositional sequences however are characterized by different mean MS values according to their general sedimentary settings. [less ▲]

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See detailRefining lithostratigraphy, cyclostratigraphy and magnetostratigraphy in Italian reference sections of Hauterivian age (Bosso, Monte Acuto and Frontone) for future comparison of cyclostratigraphic results
Wouters, Sébastien ULiege; Satolli, Sara; Martinez, Mathieu et al

Poster (2018, April)

Astrochronology has proven to be a powerful method to constrain the duration of geological periods. However in some geological periods, cyclostratigraphic studies give diverging results. For instance the ... [more ▼]

Astrochronology has proven to be a powerful method to constrain the duration of geological periods. However in some geological periods, cyclostratigraphic studies give diverging results. For instance the duration of the Hauterivian Stage was estimated as 3.5 myr in central Italy, and 5.9 ± 0.4 myr in South-Eastern France and South-Eastern Spain (Martinez et al., 2015, Sprovieri et al., 2006). However the comparison of the cyclostratigraphic results of different sections requires to have an independent stratigraphic framework. For future comparison we are refining the lithostratigraphy, cyclostratigraphy and magnetostratigraphy of Italian sections by high resolution logging and sampling. This has already led to identify thin shale beds sequences that can be correlated between sections. These sequences can be useful for further study of the Maoilica Formation. Indeed such marker beds are the only stratigraphic markers that can be directly observed on the field. Their identification could therefore help to define the age of new sections. [less ▲]

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See detailSilurian deltaic progradation, Tassili n’Ajjer plateau, south-eastern Algeria: Sedimentology, ichnology and sequence stratigraphy
Djouder, Hocine ULiege; Lüning, Sebastian; Da Silva, Anne-Christine ULiege et al

in Journal of African Earth Sciences (2018), 142

The economic potential for unconventional shale oil and gas production in the Silurian of the Berkine – Ghadames and Illizi basins (BGI) in south-eastern Algeria has been recently confirmed through ... [more ▼]

The economic potential for unconventional shale oil and gas production in the Silurian of the Berkine – Ghadames and Illizi basins (BGI) in south-eastern Algeria has been recently confirmed through exploration drilling. The aim of the present paper attempts a better understanding of the Intra-Tassilian depression within the entire Silurian of the Tassili n’Ajjer plateau. The continuous deposits of the Silurian are exposed at the southern margin of the prolific BGI basins, in the Tassili n’Ajjer plateau, offering the chance to understand the sedimentology, ichnology, and to present a detailed sequence stratigraphy framework for the region. The 410 m-thick clastic Silurian sedimentary strata are subdivided into three formations in the context of sequence stratigraphy, namely: (i) the Oued Imihrou Fm. (Llandoverian) overlain by (ii) the Atafaïtafa Fm. (late Llandoverian to Wenlockian), and (iii) the Oued Tifernine Fm. (late Wenlockian to Pridolian). These can be also distinguished across the entire investigated area and laterally traceable over kilometers. Clear cyclic stacking patterns are identified within the four studied sections showing progressively a general trend of thickening- and coarsening-upward, over a complete 2nd-order megasequence (SIL-1 MS). This transgressive-regressive succession suggests deltaic progradation, shallowing and basin infilling as evidenced by numerous diagnostic sedimentary features and trace fossils, largely from eastern- to western-Tassili plateau. Indeed, the wealth of outcrop data in the Silurian siliciclastic succession enables us to distinct thirteen facies (facies A-M), ranging from shallow- to marginal-marine facies, and in turn, grouped into six facies associations (FA1-FA6). The lowermost part of the succession, which is the most prolific sources of hydrocarbons in North Africa, consists of thick organic-rich graptolite-yielding black ‘hot’ shales and ‘lean’ shales with sparse bioturbation with small Thalassinoides belonging to the distal Cruziana ichnofacies. In contrast, the uppermost part of the Silurian deposits becomes progressively coarser and fluvial in response to the progradation of the North African Akakus deltaic system, during regional sea level fall and uplifting of the region. These progradational deposits exhibit well-preserved trace fossils with moderate to high degree of bioturbation, such as Skolithos or the so-called "Tigillites" pipe-rock, Cruziana isp., Rusophycus isp., Monocraterion isp., and Syringomorpha. The SIL-1 MS is bounded by a post-glacial latest Hirnantian unconformity on the basal (SB1), as confirmed by the moderately diverse early Silurian graptolite faunas, and by the Caledonian unconformity on the top (SB7). Each of the three formations of SIL-1 MS reveals two major 3rd-order progradational sequences, commonly delineated by discontinuity surfaces (in ascending order, SB1 to SB7), and in turn, these six sequences (i.e. Si-1 to Si-6) are subdivided into at least ten shorter-term cycles. The regional extent of each unconformity is directly linked to significant facies changes and to inflection points on the global sea level curve. [less ▲]

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See detailGeochemical characterization of “Lorraine limestones” from the SaintPaul Cathedral of Liège (Belgium): assumptions for the true provenance of the building stones
Lecuit, Marie-Xavier ULiege; Fronteau, Gilles; Boulvain, Frédéric ULiege et al

in Environmental Earth Sciences (2018), 77

We investigate the provenance of the ochre building stones called “Lorraine limestones” used for architectural specifc elements of the Saint-Paul Cathedral in Liège (Belgium) between the thirteenth and ... [more ▼]

We investigate the provenance of the ochre building stones called “Lorraine limestones” used for architectural specifc elements of the Saint-Paul Cathedral in Liège (Belgium) between the thirteenth and ffteenth century. A multi-analytical approach, including archives study, petrography and Rare Earth Elements geochemistry, has been performed to characterize the stones used in the church and to compare them with ochre limestones outcropping in the north-east of the Paris Basin. Our study suggests that a very restricted geographical area near the ancient port of Donchery (Ardennes, France) including Dom-le-Mesnil and Hannogne ancient quarries of Bajocian limestones (Middle Jurassic) should clearly be regarded as the potential origin location for the stones used in the Saint-Paul Cathedral. [less ▲]

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See detailMultiple dating approach (14C, 230Th/U and 36Cl) of tsunami-transported reef-top boulders on Bonaire (Leeward Antilles) – Current achievements and challenges
RIXHON, G.; MAY, S.M.; ENGEL, M. et al

in Marine Geology (2018)

Dating the transport/deposition time of supratidal coarse-clast deposits is difficult, limiting their value for inferring frequency-magnitude patterns of high-energy wave events. On Bonaire (Leeward ... [more ▼]

Dating the transport/deposition time of supratidal coarse-clast deposits is difficult, limiting their value for inferring frequency-magnitude patterns of high-energy wave events. On Bonaire (Leeward Antilles, Caribbean), these deposits form prominent landforms, and transport by one or several Holocene tsunamis is assumed at least for the largest clasts. Although a large dataset of 14C and electron spin resonance (ESR) ages is available for major coral rubble ridges and ramparts, it is still debated whether these data reflect the timing of major events, and how these datasets are biased by the reworking of coral fragments. As an attempt to overcome the current challenges for dating the dislocation of singular boulders, three distinct dating methods are implemented and compared: (i) 14C dating of boring bivalves attached to the boulders; (ii) 230Th/U dating of post-depositional, secondary calcite flowstone and subaerial microbialites at the underside of the boulders; and (iii) surface exposure dating of overturned boulders via 36Cl concentration measurements in corals. Approaches (ii) and (iii) have never been applied to coastal boulder deposits so far. The three 14C age estimates are older than 40 ka, i.e. most probably beyond the applicability of the method, which is attributed to post-depositional diagenetic processes, shedding doubt on the usefulness of this method in the local context. The remarkably convergent 230Th/U ages, all pointing to the Late Holocene period (1.0–1.6 ka), are minimum ages for the transport event(s). The microbialite sample yields an age of 1.23 ± 0.23 ka and both flowstone samples are in stratigraphic order: the older (onset of carbonate precipitation) and younger flowstone layers yield ages of 1.59 ± 0.03 and 1.23 ± 0.03 ka, respectively. Four coral samples collected from the topside of overturned boulders yielded similar 36Cl concentration measurements. However, the computed ages are affected by large uncertainties, mostly due to the high natural chlorine concentration. After correction for the inherited component and chemical denudation since platform emergence (inducing additional uncertainty), the calculated 36Cl ages cluster between 2.5 ± 1.3 and 3.0 ± 1.4 ka for three of four boulders whilst the fourth one yields an age of 6.1 ± 1.8 ka, probably related to a higher inheritance. These 230Th/U and 36Cl age estimates are coherent with a suggested tsunami age of < 3.3 ka obtained from the investigation of allochthonous shell horizons in sediment cores of northwestern Bonaire. Whilst 230Th/U dating of post-depositional calcite flowstone appears to be the most robust and/or accurate approach, these results illustrate the potential and current limitations of the applied methods for dating the dislocation of supralittoral boulders in carbonate-reef settings. [less ▲]

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See detailPalynologie et environnements des sédiments du Dévonien de Saïda (Algérie nord occidentale)
Bougara, M; Steemans, Philippe ULiege; Le Hérissé, A. et al

in Carnets de Géologie (2017), 17(10), 191-219

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See detailCyclostratigraphy in the Hauterivian-Barremian Frielingen core (lower Saxony Basin, Germany)
Wouters, Sébastien ULiege; Bornemann, André; Erbacher, Jochen et al

Poster (2017, October)

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See detailInsights into a million-year-scale Rhenohercynian carbonate platform evolution through a multi-disciplinary approach: example of a GIvetian carbonate record from Belgium
Pas, Damien ULiege; Da Silva, Anne-Christine ULiege; Devleeschouwer, Xavier et al

in Geological Magazine (2017), 154(4), 707-739

In this paper we formulate answers to three important questions related to Givetian carbonate records and their use for reconstructing million-year past palaeoenvironmental changes. First, we provide ... [more ▼]

In this paper we formulate answers to three important questions related to Givetian carbonate records and their use for reconstructing million-year past palaeoenvironmental changes. First, we provide detailed illustrations of the fascinating diversity that shaped a significant shallow reefal platform during the early- to late-Givetian in the Rhenohercynian Ocean; secondly we improve the sedimentological model of the extensive Givetian carbonate platform in the Dinant Basin and thirdly we evaluate the application of magnetic susceptibility (MS) as a tool for long-term trend correlations and palaeoenvironmental reconstructions. These goals are reached by making sedimentological, geophysical and geochemical study of the La Thure section. Through the early-late Givetian interval we discerned eighteen microfacies ranging from a homoclinal ramp to a discontinuously rimmed shelf and then a drowning shelf. The comparison of these sedimentological results with those published in the south of the Dinant Syncline allowed us to provide an up to date model of the vertical and lateral environmental development for one of the largest Givetian carbonate platforms in Europe. This comparison also increased the knowledge on the facies belts distribution into the Dinant Basin and allowed us to highlight the Taghanic Event. Palaeo-redox proxies reveal a substantial change in the oxygenation level, from oxygen-depleted to more oxic condition, between middle and late Givetian. We demonstrated the relationship between variation in MS values and proxies for siliciclastic input (such as Si, Al). The La Thure is considered as a key section for the understanding of internal shelf settings bordering Laurussia’s south-eastern margin. [less ▲]

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See detailSedimentologic and paleoclimatic reconstructions of carbonate factory evolution in the Alborz Basin (northern Iran) indicate a global response to Early Carboniferous (Tournaisian) glaciations
Sardar Abadi, Mehrdad; Kulagina, E.; Voeten, D.F.A.E. et al

in Sedimentary Geology (2017), 348

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See detailFlow dynamics at the origin of thin clayey sand lacustrine turbidites: Examples from Lake Hazar, Turkey
Hage, Sophie; Hubert, Aurelia ULiege; Lamair, Laura ULiege et al

in Sedimentology (2017), 64

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See detailMagnetic susceptibility records for global stratigraphic correlations? New constraint in the context of carbonate platform reconstruction (Middle Devonian, Ardennes)
Pas, Damien ULiege; Da Silva, Anne-Christine ULiege; Poulain, Geoffrey et al

in 33 rd INTERNATIONAL MEETING OF SEDIMENTOLOGY, 16ème CONGRÈS FRANÇAIS DE SÉDIMENTOLOGIE (2017)

This study undertakes a multi-disciplinary approach (sedimentology, magnetic susceptibility, geochemistry and hysteresis magnetic measurement) to increase our understanding of the Ardennes Givetian ... [more ▼]

This study undertakes a multi-disciplinary approach (sedimentology, magnetic susceptibility, geochemistry and hysteresis magnetic measurement) to increase our understanding of the Ardennes Givetian platform (Belgium and France) and to address a major question on the reliability of the magnetic susceptibility (MS) records for global correlations of marine carbonate records. Sedimentological analyses on two successions lasting millions of years, reveal an extended diversity of shallow- to off-reef palaeoenvironmental settings across the platform and allow to constrain the main sea-level fluctuations and associated environmental changes throughout the Givetian in Ardennes. The comparison of the two MS profiles allows to provide correlations, despite the long distance between the sections and their different sedimentological background. However, the comparison of the MS profiles from the Ardennes with contemporaneous data from the Rhenische Schiefergebirge (Germany) does not show any evidences of correlation, challenging studies that present the MS signal as a global correlation tool. These outcomes are crucial because they have repercussions on future global and regional stratigraphic issues as well as for paleoclimatic reconstructions. Here, we provide new evidences outlining that autogenic processes, which operate at long time scale, modulate the MS signal and have a strong influence over the magnetic susceptibility records that can leads to the absence of correlation within long-term MS trends. [less ▲]

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See detailGeochemistry of Lower Devonian terrigenous sedimentary rocks from the Belgian Ardenne: Source proxy and paleogeographic reconstruction
Duchesne, Jean-Clair ULiege; Meus, Philippe ULiege; Boulvain, Frédéric ULiege

in Sedimentary Geology (2017)

Major and trace element (Rb, Sr, Ba, Zr, Ni, V, Zn, Cr, Y, Ce) compositions are studied in Lower Devonian terrigenous sediments from the Dinant Synclinorium and Ardenne Anticline (Belgian Ardenne). Five ... [more ▼]

Major and trace element (Rb, Sr, Ba, Zr, Ni, V, Zn, Cr, Y, Ce) compositions are studied in Lower Devonian terrigenous sediments from the Dinant Synclinorium and Ardenne Anticline (Belgian Ardenne). Five cross sections encompassing 148 samples in 19 formations have been studied. In the conventional [Al2O3+Fe2O3-K2O-Na2O]–[K2O]–[FeO+MgO] triangle, the rock compositions plot on the illite – chlorite tie line. This suggests that (1) the mineral association has reached equilibrium in the pressure and temperature range of the postdepositional evolution of the sediments; (2) the chemical system was open and K was a mobile component. Although the original composition of the sediment was modified, the AAFM = Al2O3/Al2O3+FeOt+MgO parameter that reflects the illite - chlorite proportions can be used as a proxy of the source composition. A principal component analysis of the major and trace element compositions permits to define the behaviour of various elements currently used as proxies of various processes. Noteworthy it is shown that Ti, V and part of Cr are correlated with the illite proportion, and part of Cr, together with Zr, with resistate minerals such as quartz, chromite and zircon. The evolution with stratigraphic age in the 5 cross sections of the AAFM proxy reveals that there is a major change in the northern part of the Ardenne Anticline at the limit between the Mirwart Formation and younger formations, corresponding approximately to the Lochkovian to Pragian transition. There is a clear shift from an aluminium-rich source to a more conventional chlorite-rich source. In the paleogeographic evolution of this region the only possible source of the aluminium-rich sediment is the Rocroi Massif. Our results confirm sedimentological and palynological evidence that a “Rocroi Island” existed in the Lochkovian Sea. A decrease in Zr concentrations with distance to the Rocroi Massif also supports this hypothesis. The stratigraphic evolution of several parameters shows local variations that can be attributed to variable streams and depositional conditions in an alluvial deltaic or shallow sea environment. [less ▲]

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See detailNEW SEDIMENTOLOGICAL DATA FROM TRIASSIC TO JURASSIC BOREHOLES (BONNERT, HAEBICHT, GROUFT, GRUND, CONSDORF) AND SECTIONS (TONTELANGE, DIFFERDANGE, RUMELANGE) FROM SOUTHERN BELGIUM AND LUXEMBOURG
Boulvain, Frédéric ULiege; Belanger, Isabelle; Colbach, Robert et al

in Professional Papers of the Geological Survey of Belgium (2017), 319

This study offers a detailed description of a series of Triassic to Jurassic representative boreholes (Bonnert, Haebicht, Grouft, Grund, Consdorf) and sections (Tontelange, Differdange, Rumelange) from ... [more ▼]

This study offers a detailed description of a series of Triassic to Jurassic representative boreholes (Bonnert, Haebicht, Grouft, Grund, Consdorf) and sections (Tontelange, Differdange, Rumelange) from southern Belgium and the Grand-Duchy of Luxembourg. Investigations provide information about microfacies, paleoenvironments and magnetic susceptibility (MS). Three sets of microfacies, corresponding to three different sedimentary systems were needed in order to address the complexity of the paleoenvironments: a transgressive mixed siliciclastic-carbonate ramp system for the Triassic to Lower Jurassic (Toarcian) interval (microfacies TT1-8), and, for the Middle Jurassic, an early transgressive low productivity mixed ramp system for the Aalenian (microfacies A1-2) and a transgressive carbonate ramp for the Lower Bajocian (microfacies B1-3). A comparison of the MS and microfacies curves shows a clear correlation between the two, suggesting that the MS signal is primary. Moreover, the MS values regularly decrease from the marine distal (TT1) to the marine proximal microfacies (TT5), with relatively weak mean MS values for sandstones and limestones, and high mean MS values for marls, argillites and ironstone. This relationship is interpreted as the consequence of local water agitation in the shallower parts of a ramp, preventing the detrital particles from settling down and to the higher sedimentation rate that dilutes the magnetic and/or paramagnetic minerals. [less ▲]

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See detailAn Introduction to the Geology of Belgium and Luxembourg
Boulvain, Frédéric ULiege; Vandenberghe, Noël

in Demoulin, Alain (Ed.) Landscapes and Landforms of Belgium and Luxembourg (2017)

Belgium and the Grand-Duchy of Luxembourg show surprising geological diversity over their small combined area of 33,114 km2. Almost all types of sedimentary rocks crop out and are generally preserved ... [more ▼]

Belgium and the Grand-Duchy of Luxembourg show surprising geological diversity over their small combined area of 33,114 km2. Almost all types of sedimentary rocks crop out and are generally preserved along well-described and easily accessible sections or in quarries. Several sections are known worldwide and are visited for stratigraphic or sedimentological purposes. Magmatic rocks are not abundant and metamorphic rocks are restricted to slates. The stratigraphic scale ranges from the Cambrian to the Quaternary, which translates to a half billion years of Earth history. This chapter provides a comprehensive overview of the different stratigraphic units, starting from the oldest and ending with the youngest. Modern stratigraphic schemes highlight formations’ geometries and interrelations. Some of the most remarkable units are further detailed. The two orogenic phases that shaped the Lower Paleozoic inliers and the Devonian-Carboniferous faulted and folded belt, i.e. the Caledonian and Variscan orogeny, are also addressed. [less ▲]

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See detailDetailed characterization of the Late Pleistocene loess sequence stratigraphy of Remicourt (Hesbaye region, Belgium) with cone penetration tests
Delvoie, Simon ULiege; Boulvain, Frédéric ULiege; Charlier, Robert ULiege et al

in Geologica Belgica (2016), 19(3-4), 281-289

Cone penetration tests (CPT) and drilling results are used to characterize the Middle Belgium loess sequence. A two scale study has been realized in the Hesbaye region (Belgium). The study on a regional ... [more ▼]

Cone penetration tests (CPT) and drilling results are used to characterize the Middle Belgium loess sequence. A two scale study has been realized in the Hesbaye region (Belgium). The study on a regional scale was performed along a 18 km long section of the high-speed railway Liège-Brussels. About 230 tests were compiled. Results show the loess thickness is very variable and can locally reach 20 m. Tertiary deposits become continuous and they rapidly thicken from Waremme to the West. The lower surface of the Tertiary deposits is characterized by a 0.3% apparent dipping to the NW. The dipping likely results from the Ardenne Massif uplift. The local scale study focuses on the site of Remicourt located along the high-speed railway. 24 CPT tests have been carried out very close to a series of archaeological trenches. The analysis shows penetrometers are able to define some stratigraphic markers within the loess layer. The most identifiable marker is stratigraphically located around the transition between the Humiferous Complex of Remicourt and the Rocourt Pedocomplex. The lens-shape of the loess ridge is also confirmed by the penetrometers’ interpretation. Furthermore, the 3D morphology of each stratigraphic marker can be estimated. These results offer interesting perspectives for the investigation of the loess sequence related to archaeological applications. [less ▲]

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