References of "Da Silva, Anne-Christine"
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See detailMagnetic susceptibility application: A window onto ancient environments and climatic variations: Foreword
Da Silva, Anne-Christine ULg; Whalen; Hladil et al

in Geological Society Special Publication (2015), 414

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See detailThe astronomical calibration of the Givetian (Middle Devonian) timescale (Dinant Synclinorium, Belgium)
De Vleeschouwer, David; Boulvain, Frédéric ULg; Da Silva, Anne-Christine ULg et al

in Geological Society Special Publication (2015), 414

Recent advances in radiometric dating result in significant improvements in the geological timescale and provide better insight into the timing of various processes and evolutions within the Earth’s ... [more ▼]

Recent advances in radiometric dating result in significant improvements in the geological timescale and provide better insight into the timing of various processes and evolutions within the Earth’s system. However, no radiometric ages are contained within the Givetian. Consequently, the absolute ages of the Givetian Stage boundaries, as well as the stage’s duration, remain poorly constrained. As an alternative, the analysis of sedimentary cycles allows for the estimation of the duration of this stage. We examined the high-resolution magnetic susceptibility signals of four Givetian outcrops in the Givet area for a possible astronomical imprint, to fully understand the rates of evolutionary and environmental change. All four sections are firmly correlated and wavelet analyses of the magnetic susceptibility signals reveal the imprint of astronomical eccentricity forcing. The highly stable 405 kyr cycles constrain the duration of the Givetian Stage at 4.35+0.45 Myr, which is in good agreement with the International Chronostratigraphic Chart (5.0 Myr). The studied sections also exhibit an imprint of obliquity, suggesting a climatic teleconnection between low and high latitudes. The corresponding microfacies curves demonstrate similar astronomical imprint, and thereby indicate that the observed 10 5year-scale cyclicity is the result of climatic and environmental change [less ▲]

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See detailMagnetic susceptibility application – a window onto ancient environments and climatic variations
Da Silva, Anne-Christine ULg; Whalen; Hladil et al

Book published by geological Society of London (2015)

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See detailLower Carboniferous ramp sedimentation of the Central Alborz Basin, northern Iran: Integrated sedimentological and rock-magnetic studies
Sardar Abadi, Mehrdad ULg; Da Silva, Anne-Christine ULg; Mosaddegh, hossein et al

in Geological Society Special Publication (2015), 414

The Lower Carboniferous Mobarak Formation in the Alborz Basin (northern Iran) was deposited along the northeastern margin of Gondwana in a carbonate ramp setting. This paper focuses on the Tournaisian ... [more ▼]

The Lower Carboniferous Mobarak Formation in the Alborz Basin (northern Iran) was deposited along the northeastern margin of Gondwana in a carbonate ramp setting. This paper focuses on the Tournaisian stratigraphic interval of this formation that crops out at the Jaban section in the southwestern Central Alborz Basin. The following facies associations, representing different ramp palaeoenvironments, have been identified: (1) mudstone–wackestone outer-ramp facies; (2) crinoidal to skeletal grainstone–packstone mid-ramp facies; (3) peloidal to crinoidal grainstone–packstone inner-ramp facies; and (4) coastal facies, which include a variety of microbial laminated to oncoidal grainstones and mudstones with evaporitic pseudomorphs. This ramp profile was affected by frequent storms that were responsible for the formation of several skeletal to non-skeletal shoals in the distal mid-ramp to the most proximal inner-ramp areas. The development of the skeletal to non-skeletal shoals along the sea side of the ramp formed a semi-enclosed lagoon sensitive to the influence of both high tides and storm surges.The magnetic susceptibility (xin) of all the samples was measured and compared with that of the facies from which the sample was taken. There is a clear link between xin and the facies; the average xin values were higher for the distal facies than for the proximal facies. The xin profile of this Lower Carboniferous carbonate sequence reflects stratigraphic variations in response to relative changes in sea level and the input of detrital materials. In the context of the sequence stratigraphic framework, the average xin values for lowstand and transgressive systems tract deposits are higher than for the highstand systems tract deposits. The clear link between xin and facies indicates at least a partly preserved primary xin signal related to the detrital inputs. However, to obtain a better understanding of the nature and origin of the minerals carrying the xin, we performed hysteresis measurements on selected samples. It appears that the xin signal is mainly carried by lowcoercivity ferromagnetic minerals such as magnetite, with a mixture of relatively coarse grains (detrital fraction) and ultra-fine grains (probably formed during diagenesis). [less ▲]

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See detailFreikofel Formation
Pondrelli, Monica; Pas, Damien ULg; Spalletta, Claudia et al

in Abhandlungen der Geologischen Bundesanstalt (2015), 69

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See detailDiversity and correlation of Givetian records in southern Belgium
Pas, Damien ULg; Poulain, Geoffrey; Labaye, Corentin et al

in Berichte des Institutes für Erdwissenschaften der Karl-Franzens-Universität Graz (2014, August), 19

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See detailTassili n’Ajjer (Sahara Oriental Algérien) – Résultats préliminaires sur le Silurien-Dévonien
Djouder, Hocine ULg; Boulvain, Frédéric ULg; Da Silva, Anne-Christine ULg et al

in Journée Thématique de l’Association des Sédimentologistes Français (ASF) « Diagenèse : avancées récentes et perspectives » (2014, July)

Les gisements atypiques non-conventionnels, à roches sédimentaires faiblement perméables, ainsi que les « sources rocks » constituent une source pétrolière majeure, attirant de plus en plus l’industrie ... [more ▼]

Les gisements atypiques non-conventionnels, à roches sédimentaires faiblement perméables, ainsi que les « sources rocks » constituent une source pétrolière majeure, attirant de plus en plus l’industrie pétrolière, d’où un regain d’intérêt potentiel au sein du Bassin de Berkine. En effet, rien que les argiles radioactives (‘hot’) shales du Silurien sont à l’origine de 80 à 90% des hydrocarbures de la plaque Nord-africaine, et les argiles radioactives du Frasnien (source secondaire) avec des valeurs de TOC allant jusqu’à 14% (Lüning et al., 2000). L'objectif de la thèse s’agira dans un premier temps de l’analyse des diagraphies de forages (Berkine ‘subsurface’) conditionnée aux données de terrain (Tassili n’Ajjer sur affleurements) et de sismique réflexion. Ceci afin de réaliser la modélisation 2D et 3-D des corps réservoirs et de la roche mère, à l’aide du logiciel Petrel©. Et au final, la cartographie des unités de la série Silurien-Dévonien dans le but de définir les « Plays » potentielles aux futures plans d’exploration. Au second volet, la mise au point d’une méthodologie rigoureuse, permettant l’étude minéralogique et l’évolution diagénétique des faciès, sous différents aspect ; la quantification de la porosité, la définition des relations entre porosité et minéralogie. Ensuite caractériser les argiles radioactives du Llandoverien-Frasnien respectivement Silurien, Dévonien et minéraux associés (Lüning et al., 2004). Plus précisément les processus et mécanismes qui contrôlent les transformations des minéraux argileux (minéralogies et cristallochimies) en composante latérale mais aussi en fonction de la profondeur. Dans ce contexte, des missions de terrains seront entreprises dans les massifs du Fadnoun (Tassili Central), Oued Taïni, Oued Khabkhab ainsi que dans l’Oued Amassine (Tassili Occidental) qui nous permettront de décrire en surface les formations du Siluro-Dévonien (profondément étudiées par : Asses, A., 1987 - Massa, D., 1988 - Bekkouche, D., 1992 – IFP, Sonatrach, Beicip., 1999) qui renferment les argiles radioactives (‘hot’) shales et les niveaux réservoirs, situées à quelques centaines de kilomètres au Nord (Bassin de Berkine), sous 2500 à 3000 m de sédiments. Une première mission de terrain est déjà réalisée, ayant reçu un support financier de la R&D (Séjour de Recherche à l’étranger), ainsi que des facilitées administratives et logistiques respectivement du Ministère de la Culture et de l’office national du parc culturel du Tassili n’Ajjer (patrimoine mondial de l’UNESCO depuis 1982). D’autres missions ultérieures seront à organiser en fonction du planning du déroulement de la thèse. La première mission géologique de terrain a duré un mois sur le Plateau de Fadnoun (Tassili n’Ajjer central). Ceci dans différentes coupes géologique-type des affleurements du Silurien-Dévonien : l’Oued Imihrou, l’Oued Farzal, Gara Tihouririne (sur la route Illizi-Fort Tarat) et Isoutar (Djouder et al., 2014). Durant cette mission terrain nous avons pu assurer la concordance entre les thématiques et objectifs de départ et les réalisés sur terrain, entre autre : 1) la meilleure compréhension de la géométrie des corps sédimentaires, au sein du Plateau de Fadnoun et donc par extension dans le bassin ; 2) la description et l’analyse des faciès, grâce aux affleurements peu connus dans les oueds. Ils permettront une analyse, notamment en termes d’environnements sédimentaires, des formations du Silurien-Dévonien ; 3) application première dans son genre de la susceptibilité magnétique comme nouvel proxy, pour les corrélations lithostratigraphiques des unités du Silurien-Dévonien aux Tassilis. 4) réalisation d’un échantillonnage serré à différents niveaux pour couvrir tout l’intervalle de la dépression intra-Tassilienne et des Grès du Tassili Externe, et puis l’expédition du matériel, nécessaire aux analyses de laboratoires notamment à Liège, et collaborateurs. La confection de lames-minces (en cours) permettra l’étude de la minéralogie et de la pétrographie, et donc une meilleure compréhension des faciès et microfaciès, c’est à dire de leurs propriétés intrinsèques (systèmes hétérogènes et complexes). Les lames palynologiques permettront des datations précises de chaque niveau. Enfin, différentes analyses sur roche (minéraux argileux dans un Laboratoire partenaire de l’Université de Poitiers en France, susceptibilité magnétique, cathodoluminescence, analyses géochimiques des majeurs et des traces à l’ULg) permettront d’affiner les paramètres du paléoenvironnement (Da Silva et al., 2013). [less ▲]

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See detailIGCP-596 & IGCP 580 Join meeting and field-workshop. International Symposium in Mongolia, Ulaanbaatar, Mongolia, 5-18th August 2014, Abstract Volume
Kido, E.; Waters, J.; Ariunchimeg, Y. et al

Book published by Berichte des Institutes für Erdwissenschaften, , Karl-Franzens-Universität Graz (2014)

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See detailMIDDLE DEVONIAN SCOLECODONTS OF THE EIFEL AREA, GERMANY
Tonarova, Petra; Hints, Olle; Königshof, Peter et al

in Cerdeno, Esperanza (Ed.) The history of life: a view from the Southern Hemisphere (2014)

Scolecodonts (polychaete jaws) are common and diverse microfossils in many types of Palaeozoic marine sediments. They bring useful information on phylogeny of polychaete annelids and can be used as ... [more ▼]

Scolecodonts (polychaete jaws) are common and diverse microfossils in many types of Palaeozoic marine sediments. They bring useful information on phylogeny of polychaete annelids and can be used as palaeoenvironmental indicators, and to a lesser degree in biostratigraphy. The number of studies on Devonian scolecodonts is, however, rather limited and in most cases single-element-based classification (parataxonomy) has been used. Here we report a well preserved assemblage of scolecodonts from the type Eifel area, Germany. The studied section lies within the Blankenheim syncline, between the villages of Blankenheim and Blankenheimerdorf. It comprises shallow shelf mixed carbonate and siliciclastic deposits of Eifelian age (kockelianus and ensensis conodont Biozones, beginning of the Kačák Event Interval) that were accumulated in near shore settings on the southern margin of the former Avalonia microcontinent. The family-level composition of the recovered Eifelian polychaete fauna is generally similar to the Silurian associations known from Baltica, Laurentia and Perunica, predominated by polychaetaspids, particularly of the genus Oenonites, mochtyellids (Mochtyella) and paulinitids (Kettnerites). However, characteristic of the Eifelian fauna is the occurrence of kielanoprionids (Kielanoprion), a family that is unknown from the pre-Devonian. In the studied samples kielanoprionids reach up to 20% of the assemblage. Representatives of atraktoprionids, skalenoprionids and tetraprionids are much less common. Comparison with contemporaneous polychaete faunas from other regions is complicated due to limited number of studies. However, the Eifelian assemblage seems to be very similar to those described previously from the Middle Devonian of North America and Upper Devonian of Poland. This suggests that many Devonian polychaetes were both long-ranging and geographically widespread. Good preservation of specimens at hand brings also new information on poorly known jawed polychaete taxa and helps to elucidate some aspects of the phylogeny of the group. The research was supported by the Czech Science Foundation (project P210/12/2018), the European Union through the European Social Fund (Mobilitas grant MJD407) and FWF P 23775-B17 (Austrian Science Fund). [less ▲]

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See detailInsight into the development of a carbonate platform through a multi-disciplinary approach - A case study from the Upper Devonian slope deposits of Mount Freikofel (Carnic Alps, Austria/Italy)
Pas, Damien ULg; Da Silva, Anne-Christine ULg; Suttner, Thomas et al

in International Journal of Earth Sciences (2014), 103

The development and behavior of Million year-scaled depositional sequences recorded within Palaeozoic carbonate platform has remained poorly examined. Therefore, the understanding of palaeoenvironmental ... [more ▼]

The development and behavior of Million year-scaled depositional sequences recorded within Palaeozoic carbonate platform has remained poorly examined. Therefore, the understanding of palaeoenvironmental changes that occur in geological past is still limited. We herein undertake a multi-disciplinary approach (sedimentology, conodont biostratigraphy, magnetic susceptibility and geochemistry) of a long-term succession in the Carnic Alps which offers new insights into the peculiar evolution of one of the best example of Palaeozoic carbonate platform in Europe. The Freikofel section, located in the central part of the Carnic Alps represents an outstanding succession in a fore-reef setting, extending from the latest Givetian (indet. falsiovalis conodont Zones) to the early Famennian (Lower crepida conodont Zone). Sedimentological analysis allowed to propose a sedimentary model dominated by distal slope and fore-reef slope deposits. The most distal setting is characterized by an autochthonous pelagic sedimentation showing local occurrence of thin-bedded turbiditic deposits. In the fore-reef slope, in a more proximal setting, there is an accumulation of various autochthonous and allochthonous fine- to coarse-grained sediments originated from the interplay of gravity-flow currents derived from the shallow-water and deeper-water area. The temporal evolution of microfacies in the Freikofel section evolves in two main steps corresponding to the Freikofel (Unit 1) and the Pal (Unit 2) Limestones. Distal slope to fore-reef lithologies and associate changes are from base to top of the section: (U1) thick bedded litho- and bioclastic breccia beds with local fining upward sequence and fine-grained mudstone intercalations corresponding, in the fore-reef setting, to the dismantlement of the Eifelian – Frasnian carbonate platform during the early to late Frasnian time (falsiovalis to rhenana superzones) with one of the causes being the Late Givetian major rift pulse; (U2) occurrence of thin-bedded red nodular and cephalopod-bearing limestones with local lithoclastic grainstone intercalations corresponding to a significant deepening of the area and the progressive withdrawal of sedimentary influxes toward the basin, in relation with late Frasnian sea-level rise. Magnetic susceptibility and geochemical analyses were also performed along the Freikofel section and demonstrate the inherent-parallel link existing between variation in magnetic susceptibility values and proxy for terrestrial input. Interpretation of magnetic susceptibility in term of palaeoenvironmental processes reflect that even though distality remains the major parameter influencing magnetic susceptibility values, carbonate production and water agitation also play an important role. [less ▲]

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See detailBelgian mud mounds, facies and structure and stromatoporoid fauna
Da Silva, Anne-Christine ULg; Kershaw, S.; Boulvain, Frédéric ULg et al

in Wesenberg Lauridsen, b.; Bjerager, M. (Eds.) Cold water carbonates at high paleolatitudes from the Palaeozoic to the Reent – combining outcrops studies with core studies and geophysical imaging. Programme and abstract book (2014)

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See detailCarbonate Mounds: from Paradox to World Heritage
Henriet, Jean-Pierre; Hamoumi, N.; Da Silva, Anne-Christine ULg et al

in Marine Geology (2014), 352

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See detailSEDIMENTARY DEVELOPMENT AND MAGNETIC SUSCEPTIBILITY OF THE FRASNIAN CARBONATE PLATFORM IN WESTERN BELGIUM (DINANT SYNCLINORIUM, LA THURE SECTION)
Pas, Damien ULg; Da Silva, Anne-Christine ULg; Labaye, Corentin et al

in 14 ième ASF 2013 (Association des Sédimentologistes Français) (2013, November 07)

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See detailDEPOSITIONAL ENVIRONMENT OF THE EARLY FRASNIAN TO EARLY FAMENNIAN SLOPE DEPOSITS OF MOUNT FREIKOFEL (CARNIC ALPS, AUSTRIA/ITALY)
Pas, Damien ULg; Da Silva, Anne-Christine ULg; suttner, Thomas et al

in 14 ième ASF 2013 (Association des Sédimentologistes Français) (2013, November)

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