References of "Yans, J"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailErosion surfaces in the Ardenne-Oesling and their associated kaolinic weathering mantle
Demoulin, Alain ULiege; Barbier, F.; Deconinck, A. et al

in Landscapes and landforms of Belgium and Luxembourg (2018)

Detailed reference viewed: 28 (4 ULiège)
See detailSevere and rapid sea level changes affecting Devonian mud mounds from Belgium.
Da Silva, Anne-Christine ULiege; Yans, J.; Boulvain, Frédéric ULiege

in International Association of Sedimentologists Meeting, 22-25th June 2015, Krakow, Abstract book. (2015)

Detailed reference viewed: 21 (1 ULiège)
Full Text
Peer Reviewed
See detailFirst Clarkforkian equivalent land mammal age in the latest Paleocene basal Sparnacian facies of Europe: Fauna, flora, paleoenvironment and (bio)stratigraphy
Smith, T.; Quesnel, F.; De Plöeg, G. et al

in PLoS ONE (2014), 9(1),

The Paleocene-Eocene Thermal Maximum (PETM) is correlated with the first occurrences of earliest modern mammals in the Northern Hemisphere. The latest Paleocene Clarkforkian North American Land Mammal Age ... [more ▼]

The Paleocene-Eocene Thermal Maximum (PETM) is correlated with the first occurrences of earliest modern mammals in the Northern Hemisphere. The latest Paleocene Clarkforkian North American Land Mammal Age, that has yielded rodents and carnivorans, is the only exception to this rule. However, until now no pre-PETM localities have yielded modern mammals in Europe or Asia. We report the first Clarkforkian equivalent Land Mammal Age in the latest Paleocene deposits of the basal Sparnacian facies at Rivecourt, in the north-central part of the Paris Basin. The new terrestrial vertebrate and macroflora assemblages are analyzed through a multidisciplinary study including sedimentologic, stratigraphic, isotopic, and palynological aspects in order to reconstruct the paleoenvironment and to evaluate biochronologic and paleogeographic implications. The mammals are moderately diverse and not abundant, contrary to turtles and champsosaurs. The macroflora is exceptional in preservation and diversity with numerous angiosperms represented by flowers, fruits, seeds and wood preserved as lignite material, revealing an abundance of Arecaceae, Betulaceae, Icacinaceae, Menispermaceae, Vitaceae and probably Cornaceae. Results indicate a Late Paleocene age based on carbon isotope data, palynology and vertebrate occurrences such as the choristoderan Champsosaurus, the arctocyonid Arctocyon , and the plesiadapid Plesiadapis tricuspidens. However, several mammal species compare better with the earliest Eocene. Among these, the particular louisinid Teilhardimys musculus, also recorded from the latest Paleocene of the Spanish Pyrenees, suggests a younger age than the typical MP6 reference level. Nevertheless, the most important aspect of the Rivecourt fauna is the presence of dental remains of a rodent and a "miacid" carnivoran, attesting to the presence of two modern mammalian orders in the latest Paleocene of Europe. Interestingly, these two groups are also the only modern groups recorded from the latest Paleocene of North America, making Rivecourt the first direct equivalent to the Clarkforkian Land Mammal Age outside of North America. © 2014 Smith et al. [less ▲]

Detailed reference viewed: 20 (5 ULiège)
Full Text
Peer Reviewed
See detailFirst carbon isotope chemostratigraphy of the Ouled Abdoun phosphate Basin, Morocco; implications for dating and evolution of earliest African placental mammals
Yans, J.; Amaghzaz, M.; Bouya, B. et al

in Gondwana Research (2014), 25(1), 257-269

The well-known Maastrichtian-Ypresian vertebrate-bearing phosphate series, in the Ouled Abdoun Basin, Morocco, is classically dated using regional selachian biostratigraphic zonation. These marine ... [more ▼]

The well-known Maastrichtian-Ypresian vertebrate-bearing phosphate series, in the Ouled Abdoun Basin, Morocco, is classically dated using regional selachian biostratigraphic zonation. These marine sediments yielded Paleocene and Eocene mammals comprising the earliest known placentals from Africa. This study provides the first insight into the organic carbon isotope chemostratigraphy (δ13Corg) of the Moroccan phosphate series and a refined dating of its vertebrate-bearing levels. Four Paleocene-Eocene sections in the NE Ouled Abdoun quarries show consistent δ13Corg long term evolutions, from the base to the top: 1) positive trend in phosphorite Bed IIa, beginning with the lower Bone Bed yielding mammals such as Eritherium, Ocepeia, Abdounodus, Lahimia, of early Thanetian and Selandian age; 2) transitional negative trend in the Intercalary phosphorite Beds II/I that includes the Otodus obliquus and Phosphatherium escuilliei Bone Bed of earliest Ypresian age; 3) negative trend to the lowermost δ13Corg values that are correlative to the early-middle Ypresian interval including ETM 2 and ETM 3 hyperthermal events in the global record; 4) positive trend in chert-enriched facies containing the middle Ypresian EECO global climatic event. Our chemostratigraphic study of the Ouled Abdoun phosphate series provides a new chronostratigraphic framework for calibrating the beginning of the evolution of placental mammals in Africa. The lower Bone Bed level from the Paleocene phosphorite Bed IIa yielding Eritherium is not younger than early Thanetian, and is most likely Selandian. The Phosphatherium Bone Bed in the Intercalary Beds II/I is earliest Ypresian. The phosphorite Bed 0, from which Daouitherium probably came, is early-middle Ypresian, just below the EECO. This suggests that the first large proboscideans evolved after the PETM, during mid-Ypresian warming events. The δ13Corg study does not support the presence of Lutetian in the NE Ouled Abdoun phosphate series and suggests that a noticeable part of the upper Thanetian is absent. © 2013 International Association for Gondwana Research. [less ▲]

Detailed reference viewed: 85 (2 ULiège)
Full Text
Peer Reviewed
See detailPaleohydrological and paleoenvironmental changes recorded in terrestrial sediments of the Paleocene-Eocene boundary (Normandy, France)
Garel, S.; Schnyder, J.; Jacob, J. et al

in Palaeogeography, Palaeoclimatology, Palaeoecology (2013), 376

The Paleocene-Eocene boundary (55.8. Ma) is associated with the Paleocene-Eocene Thermal Maximum (PETM), which is characterized by a negative Carbon Isotope Excursion (CIE), reflecting a major ... [more ▼]

The Paleocene-Eocene boundary (55.8. Ma) is associated with the Paleocene-Eocene Thermal Maximum (PETM), which is characterized by a negative Carbon Isotope Excursion (CIE), reflecting a major perturbation of the carbon cycle, and by an extreme and rapid global warming. The Cap d'Ailly area (Upper Normandy, France), in which previous studies have revealed the Paleocene-Eocene transition, is a reference locality for organic-rich terrestrial and lagoonal deposits of the "Sparnacian" stage, widespread in Northwestern Europe. In this study, we focus on the organic matter content of the Vasterival section. Organic data (Rock-Eval, palynofacies, biomarker analyses and compound specific isotope analyses) were acquired in order to constrain the paleoenvironmental and paleohydrological changes that occurred at the Paleocene-Eocene boundary. Stable carbon isotope compositions of higher plant leaf wax n-alkanes reveal a CIE of - 4.5‰, extending throughout the second half of the studied section. Palynofacies observations reveal: (i) an abrupt shift from a closed, quiescent marsh pond to an open eutrophic swamp subjected to algal blooms, concomitant with the onset of the CIE; and (ii) the evolution from a swamp to a tidal flat due to the marine transgression that occurred during the PETM. Higher plant biomarkers and their hydrogen isotopic composition compared to nitrogen analyses suggest: (i) dry episodes just before the PETM that may help to understand the triggering of this hyperthermal event; and (ii) a moister climate associated with a stronger seasonality during the early PETM.© 2013 ElsevierB.V. [less ▲]

Detailed reference viewed: 14 (0 ULiège)
Full Text
Peer Reviewed
See detailUnraveling the Paleocene-Eocene thermal maximum in shallow marine tethyan environments: The tunisian stratigraphic record
Stassen, P.; Dupuis, C.; Steurbaut, E. et al

in Newsletters on Stratigraphy (2013), 46(1), 69-91

Despite the increasing understanding of the Paleocene-Eocene thermal maximum (PETM) in open marine environments, shallow marine settings remain relatively unexplored. We investigated an upper Paleocene to ... [more ▼]

Despite the increasing understanding of the Paleocene-Eocene thermal maximum (PETM) in open marine environments, shallow marine settings remain relatively unexplored. We investigated an upper Paleocene to lower Eocene shallow-water sequence near Kalaat Senan in Tunisia (Sidi Nasseur and Wadi Mezaz sections) in order to generate a stratigraphic framework of the PETM in a shallow marine fine-grained siliciclastic setting of the Southern Tethys. These sections expose the top part of the El Haria Formation (Fm.), the Chouabine Fm. and the lower part of the limestone bearing El Garia Fm., covering the upper Paleocenelower Eocene (NP9a to NP11). The PETM interval is situated near the top of the El Haria Fm. and the regional stratigraphy is compared to the well-known Egyptian setting. The isotope record of total organic carbon (δ13Corg) reveals the characteristic negative carbon isotope excursion (CIE), comparable to the δ13Corg record of the Global Boundary Stratotype Section and Point of the Eocene at Dababiya (Egypt). Although the Tunisian PETM interval is quite expanded, no anomalous beds are observed and only the CIE "core" is partly represented as the top part of the PETM is truncated. In addition to a well-expressed CIE, the position of the Paleocene-Eocene boundary is supported by the appearance of nannoplankton (Discoaster araneus) and foraminiferal (e. g. Acarinina multicamerata) marker taxa. Furthermore, ostracode and benthic foraminiferal turnovers coincide with the onset of the PETM and are characterized by the disappearance of many common Paleocene taxa (e. g. Frondicularia aff. phosphatica) in this area. The lowest occurrences of Alocopocythere attitogonensis and Buntonia? tunisiensis (ostracodes), Reophax sp. 1 (benthic foraminifera) and Fasciculithus tonii (calcareous nannoplankton) may be applicable for regional correlation. These results indicate that characteristic PETM taxa evolved and/or dispersed immediately after the main δ13Corg shift. © 2013 Gebrüder Borntraeger, Stuttgart, Germany. [less ▲]

Detailed reference viewed: 31 (2 ULiège)
Full Text
Peer Reviewed
See detailThe Palaeocene/Eocene boundary section at Zumaia (Basque-Cantabric Basin) revisited: New insights from high-resolution magnetic susceptibility and carbon isotope chemostratigraphy on organic matter (δ 13C org)
Storme, Jean-Yves ULiege; Devleeschouwer, X.; Schnyder, J. et al

in Terra Nova (2012), 24(4), 310-317

The Zumaia section, the most complete and representative section of the early Palaeogene (hemi)-pelagic succession of the Pyrenees, is widely acknowledged as a key reference for the Palaeocene-Eocene ... [more ▼]

The Zumaia section, the most complete and representative section of the early Palaeogene (hemi)-pelagic succession of the Pyrenees, is widely acknowledged as a key reference for the Palaeocene-Eocene boundary. New high-resolution δ 13C org of the Zumaia section (-23.8 to -28.8‰) confirms the position of the Carbon Isotope Excursion and enhances the distinction between the different steps of the CIE/PETM event. According to new magnetic susceptibility data and detailed cycle counting, the entire duration of the CIE/PETM in Zumaia is estimated in ∼168±16ka. Moreover, the investigation of palynofacies and low-field magnetic susceptibility reveal significant detrital influx during the interval. Several magnetic susceptibility phases and trends are recognised and are interpreted in terms of sea-level fluctuations before, during and after the PETM. Coupled with results from other sections, our data reveal the presence of an unconformity followed by an eustatic sea-level rise (TST) in the latest Palaeocene. © 2012 Blackwell Publishing Ltd. [less ▲]

Detailed reference viewed: 36 (0 ULiège)
Full Text
Peer Reviewed
See detailCycles of humid-dry climate conditions around the P/E boundary: New stable isotope data from terrestrial organic matter in Vasterival section (NW France)
Storme, Jean-Yves ULiege; Dupuis, C.; Schnyder, J. et al

in Terra Nova (2012), 24(2), 114-122

The Palaeocene/Eocene boundary (P/EB) and the Palaeocene-Eocene Thermal Maximum (55.8Ma) are defined stratigraphically based on carbon isotope ratios of various materials. Here, the position of the P/EB ... [more ▼]

The Palaeocene/Eocene boundary (P/EB) and the Palaeocene-Eocene Thermal Maximum (55.8Ma) are defined stratigraphically based on carbon isotope ratios of various materials. Here, the position of the P/EB is refined in the terrestrial-lacustrine and swampy Vasterival section (Upper Normandy coast, France) by using carbon isotopes measured on dispersed organic matter (δ 13C org). Moreover, nitrogen isotopes on dispersed organic matter (δ 15N org) are, for the first time in the Palaeogene record, associated with carbon isotope and lithological data to constrain palaeoclimatic and environmental changes around the P/EB in a terrestrial environment. Humid-dry fluctuations before and during this key interval in Earth history are suggested. © 2012 Blackwell Publishing Ltd. [less ▲]

Detailed reference viewed: 17 (1 ULiège)
Full Text
Peer Reviewed
See detailUn nouveau site à vertébrés terrestres juste après la limite Paléocène-Eocène, dans la Formation de Mortemer en Haute-Normandie, France
Smith, T.; Dupuis, C.; Folie, A. et al

in Comptes Rendus Palevol (2011), 10(1), 11-20

European terrestrial vertebrate sites of the Upper Paleocene-Lower Eocene deposits are predominantly known from the central and eastern parts of the Paris Basin. However, several outcrops covering this ... [more ▼]

European terrestrial vertebrate sites of the Upper Paleocene-Lower Eocene deposits are predominantly known from the central and eastern parts of the Paris Basin. However, several outcrops covering this interval are scattered along the Upper Normandy coast, in the western part of the Paris Basin. Here we report the discovery of a new terrestrial vertebrate site in the Mortemer Formation, at the top of the cliffs of Sotteville-sur-Mer in Upper Normandy, France. The vertebrate level is situated about 1.5. m above the onset of the Paleocene-Eocene Carbon Isotope Excursion (CIE) based on dispersed organic carbon and is therefore Earliest Eocene in age. The vertebrate fauna is composed of fish, amphibians, lizards and mammals, including the earliest peradectid marsupials and paromomyid plesiadapiform of Europe. A diverse and rich charophyte flora is well represented throughout the lower part of the outcrop and allows the conclusion that the CIE falls in the Peckichara disermas biozone. La plupart des sites à vertébrés terrestres du Paléocène supérieur-Eocène inférieur d'Europe sont connus du Centre et de l'Est du Bassin de Paris. Cependant, plusieurs affleurements de cet intervalle de temps sont éparpillés le long de la côte en Haute-Normandie dans l'Ouest du Bassin de Paris. Dans cet article, nous faisons état de la découverte d'un nouveau site à vertébrés terrestres dans la Formation de Mortemer, au sommet des falaises de Sotteville-sur-Mer en Haute-Normandie, France. Le niveau à vertébrés est situé environ 1,5. m au-dessus du point initial de l'Excursion Isotopique du Carbone de la limite Paléocène-Eocène (CIE), mise en évidence à partir du carbone organique dispersé. Il est donc daté de l'Eocène basal. La faune de vertébrés comprend des poissons, des amphibiens, des lézards et des mammifères dont les plus anciens marsupiaux peradectidés et le plus ancien plésiadapiforme paromomyidé d'Europe. Une flore riche et variée de charophytes, bien distribuée le long de la partie inférieure de l'affleurement permet de préciser que la CIE est située dans la biozone à Peckichara disermas. © 2010 Académie des sciences. [less ▲]

Detailed reference viewed: 16 (0 ULiège)
Full Text
Peer Reviewed
See detailRecognition and implication of tectonic loading-induced reheating in the northern Variscan front (Belgium and northern France), based on an illite Kubler index and oxygen isotope study
Han, G.; Yans, J.; Goudalier, M. et al

in International Journal of Earth Sciences (2003), 92(3), 348-363

Illite Kubler index (KI) and oxygen isotope (brachiopods and micrites) investigations have been performed on more than 300 Frasnian limestones sampled in one borehole and numerous outcrops in the Dinant ... [more ▼]

Illite Kubler index (KI) and oxygen isotope (brachiopods and micrites) investigations have been performed on more than 300 Frasnian limestones sampled in one borehole and numerous outcrops in the Dinant Synclinorium (Belgium, northern France) of the northern Variscan front. The illite Kubler index and delta(18)O data of a 3-km-thick, tectonically repeated Frasnian series from the Focant borehole are compared with their surrounding surface correspondents and document in-situ reheating induced by Variscan tectonic loading, which post-dated sedimentary burial alteration. The boundary between these two thermal processes (sedimentary burial and tectonic loading) on the Focant profile corresponds to an important location where the heat induced by the tectonic loading was equivalent to that Frasnian strata suffered during maximum sedimentary burial. Mainly based on this knowledge and on a former conodont colour alteration index study, the thickness of the eroded thrust sheet in the Focant area is estimated to be around 3,000 m. Oxygen isotopic exchange in these Frasnian closed carbonate systems, occurring under highest-grade diagenesis and anchimetamorphism, records two events. Brachiopods present a quite different and more homogeneous pattern, due to their higher resistance to heat alteration. These thermal events caused both delta(18)O records to become increasingly lighter than the presumed original seawater signature. The comparison between KI and delta(18)O profiles indicates that illite KI analysis is more appropriate than delta(18)O in highlighting the temperature variations in the burial metamorphism at the periphery of orogenic belts. [less ▲]

Detailed reference viewed: 36 (1 ULiège)
Full Text
Peer Reviewed
See detailMultidisciplinary study of the Wealden deposits in the Mons Basin (Belgium): a progress report.
Yans, J; Spagna, P; Foucher, JC et al

in Aardkundige Mededelingen (2002), 12

Detailed reference viewed: 28 (2 ULiège)