A group of asteropygine trilobites with 10 thoracic segments from the lower Emsian to lowermost Eifelian of western Europe and northwest Africa is deemed monophyletic. Available names for this clade are Hollardops Morzadec, 1997, Philipsmithiana Lieberman & Kloc, 1997, Modellops Lieberman & Kloc, 1997 and Pennarbedops Bignon & Crônier, 2013, the first of which has priority. Well-preserved Hollardops specimens from southern Morocco have revealed previously undescribed details of the mineralised exoskeleton that are interpreted here as coaptative and sensory devices. It is proposed that Hollardops, like many other asteropygines, practised a dual mode of coaptation: fully locked enrolment was alternated with a retracted pygidium, allowing temporary influx of oxygenated seawater and excretion through slits between the pygidial lappets. This putative ‘breathing device’ enabled the trilobite to remain enrolled for a longer period of time while maintaining vital body functions. A poor understanding of the problematic type species of Hollardops, H. mesocristatus (Le Maître, 1952), has clouded actual diversity in Algeria and Morocco. Hollardops klugi sp. nov. is the oldest known member of the genus and extends its confirmed stratigraphic range into the lower Emsian. Two species, H. kyriarchos sp. nov. and H. multatuli sp. nov., are recorded from just above the base of the upper Emsian. Additionally, H. angustifrons sp. nov., H. luscus sp. nov. and the first well-preserved specimens of H. boudibensis Morzadec, 2001 are recorded from the upper Emsian. The types of H. hyfinkeli (Lieberman & Kloc, 1997) and H. burtandmimiae (Lieberman & Kloc, 1997) are refigured and original species concepts reiterated. Feruminops Haas, 1968, including its junior subjective synonym Morzadecops Bignon & Crônier, 2013, from the lower Emsian of Morocco and Türkiye, may comprise the sister group of Hollardops. Additionally, the enrolment strategies and systematics of several other members of Asteropyginae are discussed. Platykardiapyge gen. nov. (type species: Metacanthina maderensis Morzadec, 2001) is erected for a group of Pragian–early Emsian asteropygines from Morocco, Spain and Türkiye with a widely heart-shaped pygidium and comparatively many pygidial pleurae, among other features. Bignonops gen. nov. (type species: Kayserops tamnrhertus Chatterton et al., 2006) is erected for some species previously included in Gandlops Bignon & Crônier, 2013. Minicryphaeus suavius sp. nov. is described from the lower Emsian of Morocco. The identity and generic affinity of the oldest known asteropygine, Ganetops gdoumontensis (Asselberghs, 1930) from the Pridolian of Belgium, are discussed.
{"title":"Functional morphology, coaptation and palaeoecology of Hollardops (Trilobita, Acastidae), with descriptions of new species and two new genera from the Devonian of Morocco","authors":"Allart P. VAN VIERSEN, Gerald J. Kloc","doi":"10.20341/gb.2022.005","DOIUrl":"https://doi.org/10.20341/gb.2022.005","url":null,"abstract":"A group of asteropygine trilobites with 10 thoracic segments from the lower Emsian to lowermost Eifelian of western Europe and northwest Africa is deemed monophyletic. Available names for this clade are Hollardops Morzadec, 1997, Philipsmithiana Lieberman & Kloc, 1997, Modellops Lieberman & Kloc, 1997 and Pennarbedops Bignon & Crônier, 2013, the first of which has priority. Well-preserved Hollardops specimens from southern Morocco have revealed previously undescribed details of the mineralised exoskeleton that are interpreted here as coaptative and sensory devices. It is proposed that Hollardops, like many other asteropygines, practised a dual mode of coaptation: fully locked enrolment was alternated with a retracted pygidium, allowing temporary influx of oxygenated seawater and excretion through slits between the pygidial lappets. This putative ‘breathing device’ enabled the trilobite to remain enrolled for a longer period of time while maintaining vital body functions. A poor understanding of the problematic type species of Hollardops, H. mesocristatus (Le Maître, 1952), has clouded actual diversity in Algeria and Morocco. Hollardops klugi sp. nov. is the oldest known member of the genus and extends its confirmed stratigraphic range into the lower Emsian. Two species, H. kyriarchos sp. nov. and H. multatuli sp. nov., are recorded from just above the base of the upper Emsian. Additionally, H. angustifrons sp. nov., H. luscus sp. nov. and the first well-preserved specimens of H. boudibensis Morzadec, 2001 are recorded from the upper Emsian. The types of H. hyfinkeli (Lieberman & Kloc, 1997) and H. burtandmimiae (Lieberman & Kloc, 1997) are refigured and original species concepts reiterated. Feruminops Haas, 1968, including its junior subjective synonym Morzadecops Bignon & Crônier, 2013, from the lower Emsian of Morocco and Türkiye, may comprise the sister group of Hollardops. Additionally, the enrolment strategies and systematics of several other members of Asteropyginae are discussed. Platykardiapyge gen. nov. (type species: Metacanthina maderensis Morzadec, 2001) is erected for a group of Pragian–early Emsian asteropygines from Morocco, Spain and Türkiye with a widely heart-shaped pygidium and comparatively many pygidial pleurae, among other features. Bignonops gen. nov. (type species: Kayserops tamnrhertus Chatterton et al., 2006) is erected for some species previously included in Gandlops Bignon & Crônier, 2013. Minicryphaeus suavius sp. nov. is described from the lower Emsian of Morocco. The identity and generic affinity of the oldest known asteropygine, Ganetops gdoumontensis (Asselberghs, 1930) from the Pridolian of Belgium, are discussed.","PeriodicalId":12812,"journal":{"name":"Geologica Belgica","volume":"30 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82705197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently published multidisciplinary studies discussed the glauconiferous sand units of the Berchem and Diest formations in large temporary outcrops near the Antwerp International Airport, east of the City of Antwerp, northern Belgium. At this location, the upper Miocene Diest Formation was subdivided into an upper Deurne Member and a lower, recently introduced, Borsbeek Member. In the current study, Cone Penetration Tests performed near the outcrops were used to geotechnically characterize the exposed units for regional correlations. For the Kiel and Antwerpen members of the middle Miocene Berchem Formation, the geotechnical expressions are nearly identical to those recently described further west in the City of Antwerp area. Contrary to the latter area, however, the upper part of the Antwerpen Member is missing, due to erosion below the Borsbeek Member. This erosion reached up to the level of a regionally occurring, compact shell bed in the middle of the Antwerpen Member, which may have protected the underlying sand from further erosion. Throughout the study area, the Borsbeek and Deurne members each show a consistent geotechnical facies, allowing for them to be distinguished on electric CPTs and thus for more reliable predictions of their areas of occurrence.
{"title":"Cone Penetration Test characterization of middle and upper Miocene lithostratigraphic units near Antwerp International Airport","authors":"J. Deckers, Stijn Goolaerts","doi":"10.20341/gb.2022.002","DOIUrl":"https://doi.org/10.20341/gb.2022.002","url":null,"abstract":"Recently published multidisciplinary studies discussed the glauconiferous sand units of the Berchem and Diest formations in large temporary outcrops near the Antwerp International Airport, east of the City of Antwerp, northern Belgium. At this location, the upper Miocene Diest Formation was subdivided into an upper Deurne Member and a lower, recently introduced, Borsbeek Member. In the current study, Cone Penetration Tests performed near the outcrops were used to geotechnically characterize the exposed units for regional correlations. For the Kiel and Antwerpen members of the middle Miocene Berchem Formation, the geotechnical expressions are nearly identical to those recently described further west in the City of Antwerp area. Contrary to the latter area, however, the upper part of the Antwerpen Member is missing, due to erosion below the Borsbeek Member. This erosion reached up to the level of a regionally occurring, compact shell bed in the middle of the Antwerpen Member, which may have protected the underlying sand from further erosion. Throughout the study area, the Borsbeek and Deurne members each show a consistent geotechnical facies, allowing for them to be distinguished on electric CPTs and thus for more reliable predictions of their areas of occurrence.","PeriodicalId":12812,"journal":{"name":"Geologica Belgica","volume":"40 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82426591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Twenty taxa of Lower Givetian rugose corals have been investigated in the Dreimühlen Formation from the Meerbüsch quarry, in the Eifel Hills. The fauna consists mostly of solitary coralla associated with some fasciculate specimens of Disphyllum caespitosum (Goldfuss, 1826) and with large massive colonies of Argutastrea briceae (Rohart, 1988). The genus Marennophyllum n. gen. is introduced with Cystiphylloides marennense Coen-Aubert, 2019 as type species to include the solitary species previously assigned to the fasciculate genus Cystiphylloides Chapman, 1893. Three species are new: Marennophyllum wenningi n. sp., Grypophyllum schroederi n. sp. and Macgeea mistiaeni n.sp. The stratigraphic distribution of the material observed in Meerbüsch quarry is compared with that of the Middle Devonian in the Eifel Hills as a whole, the southern part of Belgium, and other countries of Western Europe. Some species such as Acanthophyllum heterophyllum (Milne-Edwards & Haime, 1851), A. vermiculare (Goldfuss, 1826), Grypophyllum convolutum (Wedekind, 1925), Stringophyllum acanthicum (Frech, 1885) and Aristophyllum luetti Coen-Aubert, 1997 are also present at the northern margin of Gondwana (Ma’der in Morocco, Zemmour in Mauritania, and Alborz Mountains in Iran). The occurrence of Heliophyllum cf. cribellum Oliver & Sorauf, 2002 in Meerbüsch quarry suggests an Eastern North American influence.
{"title":"The highly diversified rugose coral fauna from the Lower Givetian Meerbüsch quarry in the Eifel Hills (Germany)","authors":"M. Coen-Aubert","doi":"10.20341/gb.2022.003","DOIUrl":"https://doi.org/10.20341/gb.2022.003","url":null,"abstract":"Twenty taxa of Lower Givetian rugose corals have been investigated in the Dreimühlen Formation from the Meerbüsch quarry, in the Eifel Hills. The fauna consists mostly of solitary coralla associated with some fasciculate specimens of Disphyllum caespitosum (Goldfuss, 1826) and with large massive colonies of Argutastrea briceae (Rohart, 1988). The genus Marennophyllum n. gen. is introduced with Cystiphylloides marennense Coen-Aubert, 2019 as type species to include the solitary species previously assigned to the fasciculate genus Cystiphylloides Chapman, 1893. Three species are new: Marennophyllum wenningi n. sp., Grypophyllum schroederi n. sp. and Macgeea mistiaeni n.sp. The stratigraphic distribution of the material observed in Meerbüsch quarry is compared with that of the Middle Devonian in the Eifel Hills as a whole, the southern part of Belgium, and other countries of Western Europe. Some species such as Acanthophyllum heterophyllum (Milne-Edwards & Haime, 1851), A. vermiculare (Goldfuss, 1826), Grypophyllum convolutum (Wedekind, 1925), Stringophyllum acanthicum (Frech, 1885) and Aristophyllum luetti Coen-Aubert, 1997 are also present at the northern margin of Gondwana (Ma’der in Morocco, Zemmour in Mauritania, and Alborz Mountains in Iran). The occurrence of Heliophyllum cf. cribellum Oliver & Sorauf, 2002 in Meerbüsch quarry suggests an Eastern North American influence.","PeriodicalId":12812,"journal":{"name":"Geologica Belgica","volume":"8 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90725474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mustelus is a problematic genus in palaeoichthyology. Due to the scarcity of fossil teeth, relative homogeneity in tooth morphology and the lack of published extant dentitions, the early history of smooth-hound sharks remains poorly understood. Recently, two teeth were collected in the Tortonian Deurne Member (Diest Formation) near Antwerp (Belgium). Surprisingly, a detailed SEM-based comparison with the extant North-Eastern Atlantic species (Mustelus mustelus, Mustelus asterias, Mustelus punctulatus) allowed assigning the fossil teeth to Mustelus aff. punctulatus. Today, this species is largely restricted to the Mediterranean and lies at the very base of the placental Mustelus clade evolution. Until now, this species remained unrecognized in the existing fossil record. By (re)evaluating isolated teeth from other upper Miocene localities in the southern North Sea Basin, the existence of a widely distributed population of Mustelus aff. punctulatus for the late Serravallian and the Tortonian can now be postulated. Thereafter, the species disappeared from the North Sea. Until today, no single record of Mustelus punctulatus is known from the Mediterranean predating the Messinian Salinity Crisis. Therefore, it is hypothesized that the current populations have their origin in southward migration from northern, Atlantic populations, and this probably after the “Zanclean Flooding”.
{"title":"First fossil record of Mustelus aff. punctulatus Risso, 1826: new evidence for a smooth-hound shark population in the Late Miocene North Sea Basin","authors":"Jeroen VAN BOECKEL, Stijn Everaert","doi":"10.20341/gb.2022.001","DOIUrl":"https://doi.org/10.20341/gb.2022.001","url":null,"abstract":"Mustelus is a problematic genus in palaeoichthyology. Due to the scarcity of fossil teeth, relative homogeneity in tooth morphology and the lack of published extant dentitions, the early history of smooth-hound sharks remains poorly understood. Recently, two teeth were collected in the Tortonian Deurne Member (Diest Formation) near Antwerp (Belgium). Surprisingly, a detailed SEM-based comparison with the extant North-Eastern Atlantic species (Mustelus mustelus, Mustelus asterias, Mustelus punctulatus) allowed assigning the fossil teeth to Mustelus aff. punctulatus. Today, this species is largely restricted to the Mediterranean and lies at the very base of the placental Mustelus clade evolution. Until now, this species remained unrecognized in the existing fossil record. By (re)evaluating isolated teeth from other upper Miocene localities in the southern North Sea Basin, the existence of a widely distributed population of Mustelus aff. punctulatus for the late Serravallian and the Tortonian can now be postulated. Thereafter, the species disappeared from the North Sea. Until today, no single record of Mustelus punctulatus is known from the Mediterranean predating the Messinian Salinity Crisis. Therefore, it is hypothesized that the current populations have their origin in southward migration from northern, Atlantic populations, and this probably after the “Zanclean Flooding”.","PeriodicalId":12812,"journal":{"name":"Geologica Belgica","volume":"49 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74260429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Boulvain, Nicolas Demaude, Fanny Toussaint, M. Coen-Aubert
This paper focuses on the Frasnian reefal development in the eastern border of the Dinant Synclinorium. Classical sections from the Durbuy–Bomal area were reevaluated for lithostratigraphy, microfacies, magnetic susceptibility (MS) and diagenesis. As regards the middle Frasnian succession, the studied area is located in a transitional zone between the Pont de la Folle/Philippeville Formations and the Moulin Liénaux/Grand Breux Formations. This succession is topped by Petit-Mont Member reef mounds. Massive mound microfacies are characteristic of the Petit-Mont and Lion Members, with fossil associations respectively dominated (from deepest to shallowest) by sponges; sponges, crinoids and corals; corals, crinoids, stromatoporoids and cyanobacteria; and microbes. Flank and off-mound microfacies consist of microbioclastic, bioclastic, crinoidal or lithoclastic bedded limestones. MS values are related to the depositional environment and regularly decrease from the off-mound to the reef mound microfacies. The reef mound diagenetic sequence is similar to that identified in other Petit-Mont buildups: cementation in the marine phreatic zone preliminary to drowning, then the development of a meteoric lens at the time of a marine regression, with dysoxic facies in the distal zones of the aquifer and, finally burial cementation and dolomitization during the Variscan tectonism.
本文重点研究了迪南特向斜东缘的弗拉斯尼礁发育。对Durbuy-Bomal地区的经典剖面进行了岩石地层、微相、磁化率和成岩作用的重新评价。关于中弗拉斯纪演替，所研究的地区位于Pont de la Folle/Philippeville组和Moulin limassnaux组/Grand Breux组之间的过渡地带。这个演替序列的顶端是小蒙特·梅伯尔礁丘。块状丘微相以小山段和狮子段为特征，化石组合从最深到最浅分别以海绵为主;海绵、海百合及珊瑚;珊瑚、海百合、层孔虫和蓝藻;和微生物。坡侧微相和坡下微相由微生物碎屑岩、生物碎屑岩、海泥岩或岩屑层状灰岩组成。MS值与沉积环境有关，从下坡微相到礁丘微相有规律地递减。该礁丘的成岩序列与其他小山构造相似:在海洋潜水带早期发生胶结作用，然后在海洋退缩时形成一个大气透镜体，在含水层的远端发育欠氧相，最后在瓦利斯卡构造运动期间发生埋藏胶结作用和白云化作用。
{"title":"Frasnian reef mounds in the Durbuy–Bomal area (eastern border of the Dinant Synclinorium, Belgium)","authors":"F. Boulvain, Nicolas Demaude, Fanny Toussaint, M. Coen-Aubert","doi":"10.20341/gb.2021.008","DOIUrl":"https://doi.org/10.20341/gb.2021.008","url":null,"abstract":"This paper focuses on the Frasnian reefal development in the eastern border of the Dinant Synclinorium. Classical sections from the Durbuy–Bomal area were reevaluated for lithostratigraphy, microfacies, magnetic susceptibility (MS) and diagenesis. As regards the middle Frasnian succession, the studied area is located in a transitional zone between the Pont de la Folle/Philippeville Formations and the Moulin Liénaux/Grand Breux Formations. This succession is topped by Petit-Mont Member reef mounds. Massive mound microfacies are characteristic of the Petit-Mont and Lion Members, with fossil associations respectively dominated (from deepest to shallowest) by sponges; sponges, crinoids and corals; corals, crinoids, stromatoporoids and cyanobacteria; and microbes. Flank and off-mound microfacies consist of microbioclastic, bioclastic, crinoidal or lithoclastic bedded limestones. MS values are related to the depositional environment and regularly decrease from the off-mound to the reef mound microfacies. The reef mound diagenetic sequence is similar to that identified in other Petit-Mont buildups: cementation in the marine phreatic zone preliminary to drowning, then the development of a meteoric lens at the time of a marine regression, with dysoxic facies in the distal zones of the aquifer and, finally burial cementation and dolomitization during the Variscan tectonism.","PeriodicalId":12812,"journal":{"name":"Geologica Belgica","volume":"55 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90951147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lower Ordovician linguliformean brachiopods from the Stavelot–Venn Massif (Belgium and Germany) are described systematically for the first time. The material comprises specimens from the Jalhay (Solwaster Member) and Ottré (Les Plattes Member) formations of Tremadocian and Floian ages, respectively. The Solwaster Member yielded a relatively diverse assemblage of nine species of lingulide (e.g. Lingulella lata, Lithobolus sp., Broeggeria sp.) and acrotretide (Acrotreta? sp.) whereas only one siphonotretide species (Celdobolus sp.) is recognised from the base of the Les Plattes Member where it is associated with conodonts of the Paroistodus proteus Zone. The assemblage from the Solwaster Member, although not abundant, is much more diverse than that of the contemporaneous Chevlipont Formation in the Brabant Massif (Thyle Valley, Belgium). Some of the taxa identified in the Stavelot–Venn Massif represent some of the youngest occurrences and first occurrences documented in Avalonia.
{"title":"Tremadocian and Floian (Ordovician) linguliformean brachiopods from the Stavelot–Venn Massif (Avalonia; Belgium and Germany)","authors":"Y. Candela, Bernard Mottequin","doi":"10.20341/gb.2021.007","DOIUrl":"https://doi.org/10.20341/gb.2021.007","url":null,"abstract":"Lower Ordovician linguliformean brachiopods from the Stavelot–Venn Massif (Belgium and Germany) are described systematically for the first time. The material comprises specimens from the Jalhay (Solwaster Member) and Ottré (Les Plattes Member) formations of Tremadocian and Floian ages, respectively. The Solwaster Member yielded a relatively diverse assemblage of nine species of lingulide (e.g. Lingulella lata, Lithobolus sp., Broeggeria sp.) and acrotretide (Acrotreta? sp.) whereas only one siphonotretide species (Celdobolus sp.) is recognised from the base of the Les Plattes Member where it is associated with conodonts of the Paroistodus proteus Zone. The assemblage from the Solwaster Member, although not abundant, is much more diverse than that of the contemporaneous Chevlipont Formation in the Brabant Massif (Thyle Valley, Belgium). Some of the taxa identified in the Stavelot–Venn Massif represent some of the youngest occurrences and first occurrences documented in Avalonia.","PeriodicalId":12812,"journal":{"name":"Geologica Belgica","volume":"8 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89520469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Lorette Cave contains a wide variety of deposits within various stratigraphical contexts. This cave is a part of the complex underground meander cut-off of the Wamme and Lomme rivers, between some swallow-holes along their two talwegs near On, Jemelle and Rochefort, and the general resurgence at Eprave. The Lorette Cave is embedded within the Givetian limestone formations of the Calestienne. This cave displays the first part with a labyrinthic structure. Some parts of the cave galleries are affected by recent tectonic activity, which dislocates some galleries and provokes collapses. The second part of the cave comprises the West Gallery, which contains the most complete sedimentary series. The “gours suspendus” (hanging gours) section is located at the western end of the gallery. The cave contains numerous and rich detrital deposits. The oldest sedimentary unit is a diamictite found in several galleries (e.g. Galerie Fontaine-Bagdad, Salle du Cataclysme). It is composed of large decametric-sized quartz and sandstone pebbles coming from the erosion of the Lower Devonian formations of the Ardenne. This deposit is older than the U/Th dating limit, i.e. 350 ka. The West Gallery exposes an area of collapsed blocks and ends in a vast room. This gallery is filled with a thick fluvial series of upper Pleistocene age and capped by speleothems of Tardiglacial to Holocene age. The large terminal chamber is clogged by flooded pits. A tributary gallery shows a sedimentary series in a subsiding pit, the “Fosse aux Lions” (Lions’ Pit). These deposits are interstratified diamictite interbedded between two fluvial units, the upper part of which displays oblique stratifications. The dating of a summit stalagmite places this set at 120 ka. The present paper analyses a section made in the southern flank of the terminal room, close to the junction with the West Gallery: the “gours suspendus” section. A large part of this section consists of a complex fluvial deposit disconformably resting on top of a compact lower clay formation. This fluvial deposit is stratified, comprising mostly diamictites interstratified with thin levels of gravel and clay. It is capped by an upper clay unit and sealed by a flowstone. Thin strata of finer-grained size sediments (coarse sand), as well as clay lenses, occur within the lower clay. The diamictites indicate a torrential origin of the sediment. At the base, just above the lower clay, some sandy channelling strata testify that one or several fluvial deposition episodes occurred. Then, torrential and probably very short-living events are separated by decantation phases. The pebbles and smaller particles are made of quartz, sandstone and muscovite that most probably originated in the Lower Devonian formations. The “gours suspendus” section provides a new illustration of the succession of sedimentation and erosion phases in Belgian caves. It is now well demonstrated that speleothems grow mainly during temperate to hot and humid clima
洛雷特洞穴在不同的地层背景下包含了各种各样的沉积物。这个洞穴是瓦姆河和洛姆河交界的复杂地下曲流的一部分，位于靠近昂河、耶梅勒河和罗什福尔河的两条支流上的一些燕子洞和埃普拉夫河的普遍回潮之间。洛雷特洞穴嵌在卡莱斯蒂安的吉田石灰岩地层中。这个洞穴展示了迷宫结构的第一部分。洞廊的某些部分受到近期构造活动的影响，使一些洞廊错位并引发崩塌。洞穴的第二部分包括西画廊，其中包含最完整的沉积系列。“挂酒”(gours suspendus)部分位于画廊的西端。洞穴中含有大量丰富的碎屑沉积物。最古老的沉积单元是在几个画廊(如Galerie fontaine - baghdad, Salle du Cataclysme)中发现的二晶岩。它由巨大的十公尺大小的石英和砂岩鹅卵石组成，这些鹅卵石来自阿登山脉下泥盆世地层的侵蚀。该矿床年龄超过U/Th定年极限，即350 ka。西画廊展示了一个倒塌的街区，并在一个巨大的房间结束。这个画廊充满了上更新世时代的厚厚的河流系列，并被缓步期至全新世的洞穴覆盖。大的终端室被淹没的水坑堵塞了。一个支流画廊展示了一个下沉坑中的沉积系列，“狮子坑”(狮子坑)。该矿床为层间杂晶岩，位于两个河流单元之间，河流单元上部呈斜层状。峰顶石笋的年代测定表明，这一组石笋的年代为120ka。本文分析了终点站南侧靠近西画廊连接处的部分:“gours suspension”部分。该剖面的大部分由不整合的复杂河流沉积组成，位于致密的下粘土地层之上。该河流沉积是层状的，主要由层间薄层砾石和粘土组成。它由上部粘土单元覆盖，并由流石密封。细粒度沉积物(粗砂)的薄层，以及粘土透镜，出现在较低的粘土中。二晶岩表明沉积物的起源是剧烈的。在底部，就在较低的粘土之上，一些砂质河道地层证明发生过一次或几次河流沉积。然后，猛烈的事件和可能非常短暂的事件被滗析阶段分开。鹅卵石和更小的颗粒是由石英、砂岩和白云母组成的，它们很可能起源于下泥盆世地层。“gours悬浮”部分为比利时洞穴的沉积和侵蚀阶段的演替提供了新的例证。现在已经充分证明，洞穴石主要生长在温带至湿热气候阶段，而碎屑填充物在寒冷/冰期沉积在洞穴中。具有沟壑形成的沉积物的物理侵蚀应放在该地区的气候历史中。像新剖面那样由粗糙碎屑形成的沟壑是由于强大的重载电流造成的。因此，洞穴内的沉积物是可用的，这只能发生在寒冷的阶段，因为没有连续的植被覆盖。在卵石层之间的沙和粘土层表明了不同的流动状态。然而，在新的部分，这种急流熔岩似乎不同于旧的二晶岩。西画廊沉积单元的沉积似乎发生在冰期-间冰期过渡时期。这项沉积学研究为确定沉积层顶部或嵌入层中的流石和石笋的年代设定了一个未来的视角，以便为Lorette洞穴填充的演化动力学与该地区气候历史的关系提出一个更可靠的时间框架。
{"title":"Stratigraphy of the Lorette Cave (Rochefort, Belgium): Study of the “gours suspendus” section","authors":"Y. Quinif, M. Legros","doi":"10.20341/gb.2021.005","DOIUrl":"https://doi.org/10.20341/gb.2021.005","url":null,"abstract":"The Lorette Cave contains a wide variety of deposits within various stratigraphical contexts. This cave is a part of the complex underground meander cut-off of the Wamme and Lomme rivers, between some swallow-holes along their two talwegs near On, Jemelle and Rochefort, and the general resurgence at Eprave. The Lorette Cave is embedded within the Givetian limestone formations of the Calestienne. This cave displays the first part with a labyrinthic structure. Some parts of the cave galleries are affected by recent tectonic activity, which dislocates some galleries and provokes collapses. The second part of the cave comprises the West Gallery, which contains the most complete sedimentary series. The “gours suspendus” (hanging gours) section is located at the western end of the gallery.\u0000The cave contains numerous and rich detrital deposits. The oldest sedimentary unit is a diamictite found in several galleries (e.g. Galerie Fontaine-Bagdad, Salle du Cataclysme). It is composed of large decametric-sized quartz and sandstone pebbles coming from the erosion of the Lower Devonian formations of the Ardenne. This deposit is older than the U/Th dating limit, i.e. 350 ka. The West Gallery exposes an area of collapsed blocks and ends in a vast room. This gallery is filled with a thick fluvial series of upper Pleistocene age and capped by speleothems of Tardiglacial to Holocene age. The large terminal chamber is clogged by flooded pits. A tributary gallery shows a sedimentary series in a subsiding pit, the “Fosse aux Lions” (Lions’ Pit). These deposits are interstratified diamictite interbedded between two fluvial units, the upper part of which displays oblique stratifications. The dating of a summit stalagmite places this set at 120 ka.\u0000The present paper analyses a section made in the southern flank of the terminal room, close to the junction with the West Gallery: the “gours suspendus” section. A large part of this section consists of a complex fluvial deposit disconformably resting on top of a compact lower clay formation. This fluvial deposit is stratified, comprising mostly diamictites interstratified with thin levels of gravel and clay. It is capped by an upper clay unit and sealed by a flowstone. Thin strata of finer-grained size sediments (coarse sand), as well as clay lenses, occur within the lower clay.\u0000The diamictites indicate a torrential origin of the sediment. At the base, just above the lower clay, some sandy channelling strata testify that one or several fluvial deposition episodes occurred. Then, torrential and probably very short-living events are separated by decantation phases. The pebbles and smaller particles are made of quartz, sandstone and muscovite that most probably originated in the Lower Devonian formations.\u0000The “gours suspendus” section provides a new illustration of the succession of sedimentation and erosion phases in Belgian caves. It is now well demonstrated that speleothems grow mainly during temperate to hot and humid clima","PeriodicalId":12812,"journal":{"name":"Geologica Belgica","volume":"31 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2021-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74101066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The sandy Zandvliet Member represents a particular, decalcified facies in the top of the Pliocene Lillo Formation in northern Belgium. Based on the correlation with nearby boreholes at the type locality of the Zandvliet Member, we were able to characterize this unit on Cone Penetration Tests. Compared to the underlying Merksem Member, the Zandvliet Member generally shows markedly lower cone resistance values. Since besides the decalcification, the Zandvliet Member is lithologically nearly identical to the underlying Merksem Member, the lower cone resistance values in the Zandvliet Member compared to the Merksem Member can only be the result of the decalcification of the Zandvliet Member. Indeed, the partly decalcified top of the Merksem Member also gives similar cone resistance values as the Zandvliet Member. Decalcification of the Eocene Brussel Sand in central Belgium is also known to have resulted in lower cone resistance values. Our Cone Penetration Test interpretations show that the thickness of the Zandvliet Member strongly varies across short distances (>10 m across 1 km). As the Zandvliet Member thickens, the underlying Merksem Member thins and vice versa. This trend is not in line with that of the under- and overlying strata, i.e. intraformational, nor with the depositional environment of these units. The thickness changes of the Zandvliet Member therefore purely reflect changes in depth of the post-depositional decalcification into the original shell-bearing sand (i.e. original Merksem Member). This confirms the existing hypothesis that the Zandvliet Member actually represents the decalcified part of the Merksem Member. The anomalous heavy mineralogy of the Zandvliet Member compared to the other members of the Lillo Formation cannot be readily explained by the acid chemical weathering which caused the decalcification. This may rather be related to a change in the primary heavy mineral signal of the upper part of the Merksem Member and equivalent Zandvliet Member compared to the underlying sequences of the Lillo Formation. The reason for the post-depositional decalcification could be similar to the Pleistocene changes in soil acidity invoked for decalcification of time-equivalent Red Crag sand in England.
{"title":"Characterization by Cone Penetration Tests of the decalcified Zandvliet Sand (Lillo Formation, North Belgium)","authors":"J. Deckers, J. Verhaegen, I. Vergauwen","doi":"10.20341/gb.2021.006","DOIUrl":"https://doi.org/10.20341/gb.2021.006","url":null,"abstract":"The sandy Zandvliet Member represents a particular, decalcified facies in the top of the Pliocene Lillo Formation in northern Belgium. Based on the correlation with nearby boreholes at the type locality of the Zandvliet Member, we were able to characterize this unit on Cone Penetration Tests. Compared to the underlying Merksem Member, the Zandvliet Member generally shows markedly lower cone resistance values. Since besides the decalcification, the Zandvliet Member is lithologically nearly identical to the underlying Merksem Member, the lower cone resistance values in the Zandvliet Member compared to the Merksem Member can only be the result of the decalcification of the Zandvliet Member. Indeed, the partly decalcified top of the Merksem Member also gives similar cone resistance values as the Zandvliet Member. Decalcification of the Eocene Brussel Sand in central Belgium is also known to have resulted in lower cone resistance values.\u0000Our Cone Penetration Test interpretations show that the thickness of the Zandvliet Member strongly varies across short distances (>10 m across 1 km). As the Zandvliet Member thickens, the underlying Merksem Member thins and vice versa. This trend is not in line with that of the under- and overlying strata, i.e. intraformational, nor with the depositional environment of these units. The thickness changes of the Zandvliet Member therefore purely reflect changes in depth of the post-depositional decalcification into the original shell-bearing sand (i.e. original Merksem Member). This confirms the existing hypothesis that the Zandvliet Member actually represents the decalcified part of the Merksem Member. The anomalous heavy mineralogy of the Zandvliet Member compared to the other members of the Lillo Formation cannot be readily explained by the acid chemical weathering which caused the decalcification. This may rather be related to a change in the primary heavy mineral signal of the upper part of the Merksem Member and equivalent Zandvliet Member compared to the underlying sequences of the Lillo Formation.\u0000The reason for the post-depositional decalcification could be similar to the Pleistocene changes in soil acidity invoked for decalcification of time-equivalent Red Crag sand in England.","PeriodicalId":12812,"journal":{"name":"Geologica Belgica","volume":"2 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87950232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Caledonian basement crops out in the middle and southern part of Belgium in two major tectonic units: the Brabant Massif in the Brabant Parautochthon and the Stavelot-Venn, Rocroi, Givonne and Serpont inliers in the Ardenne Allochthon. The main aim of this work is to achieve a chronostratigraphic correlation between the Brabant Massif and the Ardenne inliers, from the lower Cambrian to the Middle Ordovician. Throughout his career, Michel Vanguestaine established an informal acritarch biozonation for this basement, which is only linked to the international stratigraphic scale in vigour at that time. Our first step was to correlate these informal biozones with the trilobite (Cambrian) and graptolite (Ordovician) biozonations which are currently well correlated with the chronostratigraphy. Then, compilation of the literature concerning each of these sedimentary units makes it possible to assign a chronostratigraphic position to their constituent formations. This work has permitted the establishment of a complete chart of the stratigraphic correlations between the Brabant Massif and the three main Ardenne inliers (Stavelot-Venn, Rocroi and Givonne). Geological implications are discussed: the Brabant Massif and the Ardenne inliers formed a single sedimentation basin with different and rheologically contrasting basements (rift and shoulder). New arguments confirm the presence of a Caledonian orogeny in the Ardenne.
{"title":"Stratigraphic correlations between the Brabant Massif and the Stavelot, Rocroi and Givonne inliers (Belgium) and geological implications","authors":"A. Herbosch","doi":"10.20341/gb.2021.004","DOIUrl":"https://doi.org/10.20341/gb.2021.004","url":null,"abstract":"The Caledonian basement crops out in the middle and southern part of Belgium in two major tectonic units: the Brabant Massif in the Brabant Parautochthon and the Stavelot-Venn, Rocroi, Givonne and Serpont inliers in the Ardenne Allochthon. The main aim of this work is to achieve a chronostratigraphic correlation between the Brabant Massif and the Ardenne inliers, from the lower Cambrian to the Middle Ordovician. Throughout his career, Michel Vanguestaine established an informal acritarch biozonation for this basement, which is only linked to the international stratigraphic scale in vigour at that time. Our first step was to correlate these informal biozones with the trilobite (Cambrian) and graptolite (Ordovician) biozonations which are currently well correlated with the chronostratigraphy. Then, compilation of the literature concerning each of these sedimentary units makes it possible to assign a chronostratigraphic position to their constituent formations. This work has permitted the establishment of a complete chart of the stratigraphic correlations between the Brabant Massif and the three main Ardenne inliers (Stavelot-Venn, Rocroi and Givonne). Geological implications are discussed: the Brabant Massif and the Ardenne inliers formed a single sedimentation basin with different and rheologically contrasting basements (rift and shoulder). New arguments confirm the presence of a Caledonian orogeny in the Ardenne.","PeriodicalId":12812,"journal":{"name":"Geologica Belgica","volume":"62 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2021-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78742634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Baele, H. Bouzahzah, S. Papier, S. Decrée, S. Verheyden, C. Burlet, E. Pirard, Guy Franceschi, L. Dejonghe
Laser-Induced Breakdown Spectroscopy (LIBS) is a fast in-situ analytical technique based on spectroscopic analysis of atomic emission in laser-induced plasmas. Geochemical mapping at macroscopic scale using LIBS was applied to a decimetric Zn-Pb ore sample from east Belgium, which consists of alternating sphalerite and galena bands. A range of elements was detected with no or minimal spectral correction, including elements of interest for beneficiation such as Ge, Ag and Ga (although the detection of gallium could not be confirmed), and remediation, especially As and Tl. The comparison between LIBS and Energy Dispersive Spectroscopy (EDS) analyses showed that LIBS intensities reliably relate to elemental concentration although differences in spot size and detection limits exist between both techniques. The elemental images of minor and trace elements (Fe, Cu, Ag, Cd, Sb, As, Tl, Ge, Ni and Ba) obtained with LIBS revealed with great detail the compositional heterogeneity of the ore, including growth zones that were not visible on the specimen. In addition, each mineral generation has a distinct trace-element composition, reflecting a geochemical sequence whose potential metallogenic significance at the district scale should be addressed in further work. Although qualitative and preliminary, the obtained LIBS dataset already produced a wealth of information that allowed to initiate discussion on some genetical and crystallochemical aspects. Above all, LIBS appears as a powerful tool for screening geochemically large samples for the selection of zones of particular interest for further analysis.
{"title":"Trace-element imaging at macroscopic scale in a Belgian sphalerite-galena ore using Laser-Induced Breakdown Spectroscopy (LIBS)","authors":"J. Baele, H. Bouzahzah, S. Papier, S. Decrée, S. Verheyden, C. Burlet, E. Pirard, Guy Franceschi, L. Dejonghe","doi":"10.20341/gb.2021.003","DOIUrl":"https://doi.org/10.20341/gb.2021.003","url":null,"abstract":"Laser-Induced Breakdown Spectroscopy (LIBS) is a fast in-situ analytical technique based on spectroscopic analysis of atomic emission in laser-induced plasmas. Geochemical mapping at macroscopic scale using LIBS was applied to a decimetric Zn-Pb ore sample from east Belgium, which consists of alternating sphalerite and galena bands. A range of elements was detected with no or minimal spectral correction, including elements of interest for beneficiation such as Ge, Ag and Ga (although the detection of gallium could not be confirmed), and remediation, especially As and Tl. The comparison between LIBS and Energy Dispersive Spectroscopy (EDS) analyses showed that LIBS intensities reliably relate to elemental concentration although differences in spot size and detection limits exist between both techniques. The elemental images of minor and trace elements (Fe, Cu, Ag, Cd, Sb, As, Tl, Ge, Ni and Ba) obtained with LIBS revealed with great detail the compositional heterogeneity of the ore, including growth zones that were not visible on the specimen. In addition, each mineral generation has a distinct trace-element composition, reflecting a geochemical sequence whose potential metallogenic significance at the district scale should be addressed in further work. Although qualitative and preliminary, the obtained LIBS dataset already produced a wealth of information that allowed to initiate discussion on some genetical and crystallochemical aspects. Above all, LIBS appears as a powerful tool for screening geochemically large samples for the selection of zones of particular interest for further analysis.","PeriodicalId":12812,"journal":{"name":"Geologica Belgica","volume":"11 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2021-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88843117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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