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Alain Préat - One of the best experts on this subject based on the ideXlab platform.
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ostracods and rock facies across the emsian Eifelian boundary at couvin dinant synclinorium belgium
Palaeobiodiversity and Palaeoenvironments, 2017Co-Authors: Jean-georges Casier, Sébastien Maillet, Alain PréatAbstract:A moderately rich ostracod fauna is reported from the upper part of the St. Joseph Formation (Fm), the Eau Noire Fm and the lower part of the Couvin Fm in the Eau Noire section located nearby Couvin. The section that crosses the Emsian/Eifelian boundary belongs entirely to the Couvinian historical stage. The ostracod fauna observed appertains to the Eifelian Mega-Assemblage and is indicative, in the Eau Noire Fm and in the Couvin Fm, of continuous shallow open-marine environments close to the fair-weather wave-base. The sampling and the number of ostracods extracted from the St. Joseph Fm are not sufficient to make environmental inferences and the study does not demonstrate an abnormal change in the ostracod fauna neither in relation with the Eau Noire Fm/Couvin Fm boundary, nor in relation with the Emsian/Eifelian boundary. The ostracods present near the Emsian/Eifelian boundary are mentioned for the first time in the southern border of the Dinant Synclinorium and they display close relations with the Eifel Mountains (Germany) and the Holy Cross Mountains (Poland).
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Ostracods and rock facies across the Emsian/Eifelian boundary at Couvin (Dinant Synclinorium, Belgium)
Palaeobiodiversity and Palaeoenvironments, 2016Co-Authors: Jean-georges Casier, Sébastien Maillet, Alain PréatAbstract:A moderately rich ostracod fauna is reported from the upper part of the St. Joseph Formation (Fm), the Eau Noire Fm and the lower part of the Couvin Fm in the Eau Noire section located nearby Couvin. The section that crosses the Emsian/Eifelian boundary belongs entirely to the Couvinian historical stage. The ostracod fauna observed appertains to the Eifelian Mega-Assemblage and is indicative, in the Eau Noire Fm and in the Couvin Fm, of continuous shallow open-marine environments close to the fair-weather wave-base. The sampling and the number of ostracods extracted from the St. Joseph Fm are not sufficient to make environmental inferences and the study does not demonstrate an abnormal change in the ostracod fauna neither in relation with the Eau Noire Fm/Couvin Fm boundary, nor in relation with the Emsian/Eifelian boundary. The ostracods present near the Emsian/Eifelian boundary are mentioned for the first time in the southern border of the Dinant Synclinorium and they display close relations with the Eifel Mountains (Germany) and the Holy Cross Mountains (Poland).
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Late Eifelian and Early Givetian ostracod assemblages from Wellin, Hotton and On-Jemelle (Ardenne, Dinant Synclinorium, Belgium). Paleoenvironmental implications
Revue de Micropaléontologie, 2015Co-Authors: Jean-georges Casier, Sébastien Maillet, Rachida Kasimi, Alain PréatAbstract:The study of 3430 ostracods collected in the Lomme, Hanonet and Trois-Fontaines formations (Late Eifelian/Early Givetian) in four sections of the Dinant Synclinorium (Ardenne) allowed the recognition of more than 75 taxa. Their study displays the progressive evolution from an external mixed siliciclastic-carbonate ramp to a carbonate platform around the Eifelian/Givetian boundary. Ostracods from the Lomme Fm are published here for the first time. The leperditicopid ostracods are probably indicative of brackish water environments during the deposition of the Trois-Fontaines Fm, and consequently point to wet and warm climatic conditions during Early Givetian times in the Dinant Synclinorium. Their absence in widespread lagoonal environments in the upper part of the Givetian may be on the contrary related to very arid climate conditions. That important climatic change is probably in relation with the Taghanic Biocrisis.
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ostracods and lithofacies close to the Eifelian givetian boundary devonian at aisemont namur synclinorium belgium
Bulletin - Institut royal des sciences naturelles de Belgique. Sciences de la terre, 2006Co-Authors: Jean-georges Casier, Alain PréatAbstract:The paper presents the sedimentological analysis and the ostracod study of the upper part of the Riviere Fm. and of the stratotype of the Nevremont Fm. in the Aisemont section, the reference section for the Eifelian-Givetian boundary (Devonian) in the southern border of the Namur Synclinorium, Belgium. Thirteen major microfacies types are defined. Their stratigraphic succession records the transition from a mixed siliciclastic-carbonate ramp (upper Eifelian) to a carbonate platform (lower Givetian). About 6,350 ostracods were extracted. Forty species (19 in open nomenclature) are recognized in the Riviere Fm. and 48 species (27 in open nomenclature) in the Nevremont Fm. They belong exclusively to the Eifelian Mega-Assemblage and their distribution is controlled mainly by water energy and salinity variations. The sedimentological analysis and the study of ostracods are in good agreement with recent conodont study of Gouwy & Bultynck (2003). Our work confirms the position of the Riviere and Nevremont formations boundary and highlights a gap of the major part of the Hanonet and Trois-Fontaines formations of the southern Dinant Synclinorium. This hiatus is probably associated with the lowstand systems tract at the Eifelian-Givetian boundary interval in northern France and southern Belgium (Preat, 2004). The presence of Quassilites fromelennensis and Jenningsina heddebauti, indicates that a great part of the transitional zone of Gouwy & Bultynck (2003) is of Givetian age.
Jean-georges Casier - One of the best experts on this subject based on the ideXlab platform.
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ostracods and rock facies across the emsian Eifelian boundary at couvin dinant synclinorium belgium
Palaeobiodiversity and Palaeoenvironments, 2017Co-Authors: Jean-georges Casier, Sébastien Maillet, Alain PréatAbstract:A moderately rich ostracod fauna is reported from the upper part of the St. Joseph Formation (Fm), the Eau Noire Fm and the lower part of the Couvin Fm in the Eau Noire section located nearby Couvin. The section that crosses the Emsian/Eifelian boundary belongs entirely to the Couvinian historical stage. The ostracod fauna observed appertains to the Eifelian Mega-Assemblage and is indicative, in the Eau Noire Fm and in the Couvin Fm, of continuous shallow open-marine environments close to the fair-weather wave-base. The sampling and the number of ostracods extracted from the St. Joseph Fm are not sufficient to make environmental inferences and the study does not demonstrate an abnormal change in the ostracod fauna neither in relation with the Eau Noire Fm/Couvin Fm boundary, nor in relation with the Emsian/Eifelian boundary. The ostracods present near the Emsian/Eifelian boundary are mentioned for the first time in the southern border of the Dinant Synclinorium and they display close relations with the Eifel Mountains (Germany) and the Holy Cross Mountains (Poland).
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Ostracods and rock facies across the Emsian/Eifelian boundary at Couvin (Dinant Synclinorium, Belgium)
Palaeobiodiversity and Palaeoenvironments, 2016Co-Authors: Jean-georges Casier, Sébastien Maillet, Alain PréatAbstract:A moderately rich ostracod fauna is reported from the upper part of the St. Joseph Formation (Fm), the Eau Noire Fm and the lower part of the Couvin Fm in the Eau Noire section located nearby Couvin. The section that crosses the Emsian/Eifelian boundary belongs entirely to the Couvinian historical stage. The ostracod fauna observed appertains to the Eifelian Mega-Assemblage and is indicative, in the Eau Noire Fm and in the Couvin Fm, of continuous shallow open-marine environments close to the fair-weather wave-base. The sampling and the number of ostracods extracted from the St. Joseph Fm are not sufficient to make environmental inferences and the study does not demonstrate an abnormal change in the ostracod fauna neither in relation with the Eau Noire Fm/Couvin Fm boundary, nor in relation with the Emsian/Eifelian boundary. The ostracods present near the Emsian/Eifelian boundary are mentioned for the first time in the southern border of the Dinant Synclinorium and they display close relations with the Eifel Mountains (Germany) and the Holy Cross Mountains (Poland).
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Late Eifelian and Early Givetian ostracod assemblages from Wellin, Hotton and On-Jemelle (Ardenne, Dinant Synclinorium, Belgium). Paleoenvironmental implications
Revue de Micropaléontologie, 2015Co-Authors: Jean-georges Casier, Sébastien Maillet, Rachida Kasimi, Alain PréatAbstract:The study of 3430 ostracods collected in the Lomme, Hanonet and Trois-Fontaines formations (Late Eifelian/Early Givetian) in four sections of the Dinant Synclinorium (Ardenne) allowed the recognition of more than 75 taxa. Their study displays the progressive evolution from an external mixed siliciclastic-carbonate ramp to a carbonate platform around the Eifelian/Givetian boundary. Ostracods from the Lomme Fm are published here for the first time. The leperditicopid ostracods are probably indicative of brackish water environments during the deposition of the Trois-Fontaines Fm, and consequently point to wet and warm climatic conditions during Early Givetian times in the Dinant Synclinorium. Their absence in widespread lagoonal environments in the upper part of the Givetian may be on the contrary related to very arid climate conditions. That important climatic change is probably in relation with the Taghanic Biocrisis.
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ostracods and lithofacies close to the Eifelian givetian boundary devonian at aisemont namur synclinorium belgium
Bulletin - Institut royal des sciences naturelles de Belgique. Sciences de la terre, 2006Co-Authors: Jean-georges Casier, Alain PréatAbstract:The paper presents the sedimentological analysis and the ostracod study of the upper part of the Riviere Fm. and of the stratotype of the Nevremont Fm. in the Aisemont section, the reference section for the Eifelian-Givetian boundary (Devonian) in the southern border of the Namur Synclinorium, Belgium. Thirteen major microfacies types are defined. Their stratigraphic succession records the transition from a mixed siliciclastic-carbonate ramp (upper Eifelian) to a carbonate platform (lower Givetian). About 6,350 ostracods were extracted. Forty species (19 in open nomenclature) are recognized in the Riviere Fm. and 48 species (27 in open nomenclature) in the Nevremont Fm. They belong exclusively to the Eifelian Mega-Assemblage and their distribution is controlled mainly by water energy and salinity variations. The sedimentological analysis and the study of ostracods are in good agreement with recent conodont study of Gouwy & Bultynck (2003). Our work confirms the position of the Riviere and Nevremont formations boundary and highlights a gap of the major part of the Hanonet and Trois-Fontaines formations of the southern Dinant Synclinorium. This hiatus is probably associated with the lowstand systems tract at the Eifelian-Givetian boundary interval in northern France and southern Belgium (Preat, 2004). The presence of Quassilites fromelennensis and Jenningsina heddebauti, indicates that a great part of the transitional zone of Gouwy & Bultynck (2003) is of Givetian age.
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Ostracods Late Devonian mass extinction: the Schmidt quarry parastratotype (Kellerwald, Germany)
Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science, 1998Co-Authors: Jean-georges Casier, Francis LethiersAbstract:Abstract Sixty-eight ostracod species have been recognized (the benthonic one for the first time) close to the Frasnian/Famennian boundary in the Schmidt quarry parastratotype. In the Late Frasnian, ostracods belong to an assemblage of the Eifelian ecotype and to the Myodocopid ecotype. In the base of the Famennian, they belong exclusively to the Eifelian ecotype. The oxygen content of the bottom waters during the deposition of the Upper Kellwasser horizon was highly unstable whereas this horizon was known to be anoxic. The Late Devonian mass extinction, probably the second in order of magnitude during the Phanerozoic, took place in the last 5 cm of the Upper Kellwasser horizon. Twelve ostracod species recognized in the Schmidt quarry survived this exvent.
I V Vikentyev - One of the best experts on this subject based on the ideXlab platform.
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subvolcanic gabbro porphyrite and intrusive diorite and sulfide mineralization of the dzhusa volcanogenic massive sulfide deposit southern urals
Doklady Earth Sciences, 2017Co-Authors: E I Yartsev, N I Eremin, I V VikentyevAbstract:Two sequentially formed groups of dikes in the gabbro–porphyrite complex have been distinguished, the ages of which are early Eifelian (early dikes) and early Givetian (late dikes). We have estimated the temperature impact of ore contact metamorphism, which is related to dikes of the Lower Carboniferous Magnitogorsk intrusive complex. A hidden zonality of microimpurities in the ore-forming minerals has been established for the first time by the LA-ICP-MS method. The ore formation age has been determined as early Eifelian–early Givetian.
Bernd Kaufmann - One of the best experts on this subject based on the ideXlab platform.
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The recalibrated Devonian time scale repres two aspects.AbstractCalibrating the
2016Co-Authors: Bernd KaufmannAbstract:ents an important improvement of Devonian chronology regarding-bracketed U–Pb ID–TIMS zircon and monazite ages constitutes th Pragian–Emsian 409.1±3.8 Ma Lochkovian–Pragian 412.3±3.5 Macontrast, the lowest resolution is shown in the early Emsian to mid-Eifelian interval with zonal durations of up to 5.5 Ma (serotinu
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calibrating the devonian time scale a synthesis of u pb id tims ages and conodont stratigraphy
Earth-Science Reviews, 2006Co-Authors: Bernd KaufmannAbstract:The recalibrated Devonian time scale represents an important improvement of Devonian chronology regarding two aspects. Firstly, a data set of 13 biostratigraphically well-bracketed U–Pb ID–TIMS zircon and monazite ages constitutes the framework of the scale. Secondly, approximately time-linear biostratigraphic scales have been used for the interpolation between the isotopic ages. The new construction thus represents a ‘biochronometric’ time scale, which allows the assignment of numeric ages not only to stage boundaries but also to each biozone boundary. The method of interpolation applied also enables the projection of the geochronological error onto the time scale. According to the newly calibrated scale, the Devonian lasted 57.4 ± 5.7 Ma from 418.1 ± 3.0 to 360.7 ± 2.7 Ma. This is, compared to previously published time scales, the longest time span ever calculated for this period. The age interpolations for the eight stage boundaries are: Famennian–Tournaisian (= Devonian–Carboniferous) 360.7 ± 2.7 Ma Frasnian–Famennian 376.1 ± 3.6 Ma Givetian–Frasnian 383.7 ± 3.1 Ma Eifelian–Givetian 388.1 ± 2.6 Ma Emsian–Eifelian 391.9 ± 3.4 Ma Pragian–Emsian 409.1 ± 3.8 Ma Lochkovian–Pragian 412.3 ± 3.5 Ma Pridolian–Lochkovian (= Silurian–Devonian) 418.1 ± 3.0 Ma Full-size table Table options View in workspace Download as CSV The duration of the Middle Devonian is calibrated here as quite short with 8.2 Ma and the Emsian and the Famennian are the longest stages with interpolated durations of 17.2 and 15.4 Ma, respectively. Together, all Devonian stages contain 57 conodont zones (including subzones, according to the standard conodont zonation) giving a mean duration of about 1 Ma. In the highly resolved part of the time scale (mid-Eifelian to the Devonian–Carboniferous boundary), zonal resolution averages 0.6 Ma. In contrast, the lowest resolution is shown in the early Emsian to mid-Eifelian interval with zonal durations of up to 5.5 Ma (serotinus Zone).
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Conodont-based quantitative biostratigraphy for the Eifelian of the eastern Anti-Atlas, Morocco
Geological Society of America Bulletin, 1997Co-Authors: Zdzislaw Belka, Bernd Kaufmann, Pierre BultynckAbstract:The measured ranges of 52 conodont taxa present in 7 Eifelian sections of the eastern Anti-Atlas in southern Morocco have been as- sembled by graphic correlation method into a chronostratigraphic framework. The Anti- Atlas regional composite developed in this study provides much higher stratigraphic res- olution than the traditionally used conodont zonation. It allows a subdivision of the Eifelian into 65.7 composite standard units, derived from the Jebel Ou Driss section, which was se- lected as the standard reference section. The framework appears to have a linear fit to time, giving the first image of the relative duration of the conodont zones in the upper Emsian to lower Givetian interval. The costatus, kockeli- anus, and Lower varcus chrons appear to have lasted more than two times longer than the partitus, australis, and/or hemiansatus chrons. An alternative upper Eifelian-lower Givetian conodont zonation with zones of more equal duration is proposed. Several conodont index taxa in the Anti-Atlas area display an almost synchronous appearance, independent of fa- cies conditions and shelf paleobathymetry. The analysis by graphic correlation reveals significant differences in rate of sediment accu- mulation between the Tafilalt Platform, which had condensed sedimentation (2.5 m/m.y.), and the Mader Basin, characterized by rates up to 40 m/m.y. area, the Devonian rocks offer excellent condi- tions for detailed biostratigraphical studies. Their depositional history reflects the process of disin- tegration of the northern margin of the Sahara cra- ton (Wendt, 1985, 1988). In contrast to the rather uniformly developed Upper Silurian and Lower Devonian sedimentary rocks, differential subsi- dence affected the area during Eifelian time, and thus a platform to basin topography of the shelf began to originate. This phase is biostratigraphi- cally relatively well constrained. Conodonts were found in many sections, providing a base for cor- relation of Eifelian rocks in the Anti-Atlas (Bul- tynck and Hollard, 1980; Bultynck and Jacobs, 1981; Bultynck, 1985, 1987, 1989, 1991). The fauna dominated by Polygnathus elements is lo- cally very abundant, but some stratigraphically important Eifelian index taxa are rare or absent, so that the position of some zonal boundaries (e.g., the base of the Eifelian) cannot be precisely rec- ognized. This is why Bultynck (1987) proposed two alternative conodont zonations for the upper Eifelian-lower Givetian interval. In order to provide a more accurate basis for correlation of Eifelian rocks and events in north- ern Africa, we used the graphic correlation method to develop a composite standard section based on conodont data from the eastern Anti-At- las. Our regional chronostratigraphic framework (Anti-Atlas regional composite) provides a much more linear biostratigraphic subdivision than any previously used conodont zonation. It offers, moreover, the best possible stratigraphic resolu- tion, useful for detailed analysis of the sedimen- tary evolution of the study area during the Middle Devonian. This contribution constitutes a first ap- proach in the construction of the Eifelian com- posite standard with worldwide applicability. In conventional biostratigraphy, fossil zones are used to achieve correlation. The graphic cor- relation technique, however, produces a frame- work that is founded on biostratigraphy, but inte- grates all the biostratigraphic events onto a composite standard. This method was developed by Shaw (1964), and was subsequently extended (e.g., Miller, 1977; Sweet, 1979; Edwards, 1984, 1989) to be applicable to nonpaleontologic and nonunique, but chronostratigraphically signifi- cant, events (including magnetic polarity data, key lithological marker beds, various geophysical log- type data, and stable isotope logs). It constitutes a powerful tool for the analysis of synchroneity or nonsynchroneity of geologic events. Integrated with sequence stratigraphy and sedimentological data, Shaw's method of graphic correlation is one of the standard techniques applied in modern basin analysis (e.g., Neal et al., 1994). GEOLOGIC SETTING
Allart P. Van Viersen - One of the best experts on this subject based on the ideXlab platform.
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Early Middle Devonian trilobites and events in the Nismes – Vireux-Molhain area, southern border of the Dinant Synclinorium (Belgium, northern France)
Geologica Belgica, 2019Co-Authors: Allart P. Van Viersen, Peter Taghon, Benedikt MagreanAbstract:1. Introduction The Eifelian rocks that crop out in southern Belgium and northern France (Fig. 1) have long been known for their highly diversified trilobite assemblages (e.g. Gosselet, 1884; Maillieux, 1904, 1907a, 1919, 1933, 1938; Richter, 1914; Lecompte, 1962). Records in the old literature chiefly encompass lists of outdated trilobite names. These are typically grouped according to obsolete stratigraphic divisions and come without references to the specimens. The only published accounts to contain useful descriptions and illustrations are those of Maillieux (1904, 1907b, 1938). After decades of little to no trilobite research in Belgium, Struve (1982b, 1985) described several phacopids from Eifelian strata between Couvin and Vireux-Molhain. Since then, a number of papers have dealt with Eifelian trilobites in the area (e.g. Magrean, 2007; Taghon et al., 2012; van Viersen, 2015, and references therein). During field excursions over the past years in southern Belgium the authors of the present paper noticed that the early Eifelian trilobite fauna shows marked differences from that of the upper Emsian. Genera such as Acastoides and Basidechenella do not cross the Eifelian boundary. This loss is more than fully compensated by the introduction of genera not known from older strata in the region. This work is the first part in a series of descriptions of early Eifelian trilobites from the Jemelle Formation in southern Belgium and northern France. Figure 1. Geological map of t
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The ‘Mur des douaniers’, an exceptionally well-preserved Early Eifelian fossil site
Bulletin de la Société Géologique de France, 2008Co-Authors: Catherine Crônier, Allart P. Van ViersenAbstract:The ''Mur des douaniers'' biota at the former French/Belgian border contains a rich and diversified Lower Eifelian benthic fauna, and especially trilobites. Palaeobiodiversity and sedimentological analyses have led to the interpretation of the general palaeoenvironmental/palaeoecological context. This trilobite-rich locality is an exceptionally well-preserved Early Eifelian fossil site with regard to the regional scale. Unfortunately, its growing reputation led to fossil pillage and now this palaeontological site is protected as a Nature Reserve. From now on, no complementary observation of the palaeontological data, the taphonomic analysis, the ichnological, sedimentological and geochemical record can be made to provide a better palaeoecological synthesis.
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DohmiellaLütke 1990 (Trilobita) a valid proetid genus, with two new species from Belgium and Germany
Senckenbergiana Lethaea, 2006Co-Authors: Allart P. Van ViersenAbstract:Dohmiella is recorded from Belgium for the first time. The genus is represented here by at least three distinct species that occur in strata of early to latest Eifelian age, namelyDohmiella dewildei n. sp.,Dohmiella sp. 1 andDohmiella sp. 2.Dohmiella prescheri n. sp. is recorded from the lower Eifelian of the Eifel, Germany. Relationships ofGerastosGoldfuss,RhenocynproetusBasse andDohmiella are briefly discussed. Contrary to some previous studiesDohmiella is here retained as a distinct genus.