Stenen immigranten in de Zwinstreek. Natuursteen in de Onze-Lieve-Vrouwhemelvaartkerk in Damme

Uit recent onderzoek blijkt de geologische rijkdom in tal van historische gebouwen in Vlaanderen. De variatie aan natuursteen die in de pre-industriële periode als bouwmateriaal werd verwerkt, is groter dan lang werd aangenomen. In de middeleeuwen was natuursteen als vanzelf een importproduct in natuursteenarme gebieden. De Onze-Lieve-Vrouwhemelvaartkerk in Damme, het grootste en best bewaarde middeleeuwse kerkgebouw van de Zwinstreek, toont duidelijk de problematiek van de import van natuursteen in de Vlaamse kustvlakte aan. Hoewel vooral bekend als een exemplarisch gebouw van de baksteenarchitectuur in de kuststreek, bevat de OLV-kerk heel wat natuursteen. Een geologische identificatie en herkomstbepaling van de verschillende steensoorten leverde heel wat nieuwe inzichten op. Daarnaast werden de toeleveringsgebieden van bouwstenen in kaart gebracht, een relevant aandachtspunt gezien de functie van Damme als voorhaven van Brugge in de 13de en 14de eeuw. De precieze geologische identificatie van de steensoorten dient bovendien ook het hedendaagse materiële beheer van het kerkgebouw. Enkel met een accurate geologische identificatie kan de gezondheid en de levensduur van een steen worden geëvalueerd en kunnen onderbouwde keuzes voor restauratie en eventuele vervangmaterialen worden gemaakt

Late Frasnian mass extinction: Conodont event stratigraphy, global changes, and possible causes

Several abrupt changes in conodont biofacies are documented to occur synchronously at six primary control sections across the Frasnian-Famennian boundary in Euramerica. These changes occurred within a time-span of only about 100,000 years near the end of the latest Frasnian linguiformis Zone, which is formally named to replace the Uppermost gigas Zone. The conodont-biofacies changes are interpreted to reflect a eustatic rise followed by an abrupt eustatic fall immediately preceding the late Frasnian mass extinction. Two new conodont species are named and described. Ancyrognathus ubiquitus n.sp. is recorded only just below and above the level of late Frasnian extinction and hence is a global marker for that event. Palmatolepispraetriangularis n.sp. is the long-sought Frasnian ancestor of the formerly cryptogenic species, Pa. triangularis, indicator of the earliest Famennian Lower triangularis Zone. The actual extinction event occurred entirely within the Frasnian and is interpreted to have been of brief duration-from as long as 20,000 years to as short as several days. The eustatic rise-and-fall couplet associated with the late Frasnian mass extinction is similar to eustatic couplets associated with the demise of most Frasnian (F2h) reefs worldwide about 1 m.y. earlier and with a latest Famennian mass extinction about 9.5 m.y. later. All these events may be directly or indirectly attributable to extraterrestrial triggering mechanisms. An impact of a small bolide or a near miss of a larger bolide may have caused the earlier demise of Frasnian reefs. An impact of possibly the same larger bolide in the Southern Hemisphere would explain the late Frasnian mass extinction. Global regression during the Famennian probably resulted from Southern-Hemisphere glaciation triggered by the latest Frasnian impact. Glaciation probably was the indirect cause of the latest Famennian mass extinction

The red crinoidal limestone of Baelen (late Upper Devonian), a particular historical building stone with an unusual depositional setting, global geological importance and local use

Peer reviewe

New data on the incertae sedis biota and foraminifera of the mid-Famennian Baelen Member (Late Devonian, eastern Belgium)

The Baelen mud mounds in eastern Belgium represent a local member of the mid-Famennian Souverain-Pré Formation (an important carbonate interval within the Condroz Sandstone Group). The lower part of this member contains silty bioclastic wackestones and packstones that are particularly rich in the problematical algae Serrisinella and Dreesenullella. Plurilocular foraminifera (Septabrunsiina and Baelenia) and rare solitary rugose corals (Neaxon? sp.) occur within crinoidal grainstones (tempestites) interfingering with the latter bioclastic wacke-/packstones and red-stained stromatactoid spiculitic mudstones (carbonate mound core facies). Although Serrisinella is quite common in other mid- and late Famennian limestones, of Belgium, Dreesenulella is almost endemic of the Baelen Member. Both genera apparently inhabited the muddy sediment-water interface, constituting meadows probably in zones of intermittently strong bottom currents. The taxonomic similarities between Dreesenulella and Saccamminopsis are discussed, as well as their possible affinities with the Xenophophyrea and Kokomiacea. Moreover, the first stages of the Septabrunsiina–Baelenia foraminiferal lineage are analysed in detail. The taxonomic and palaoecological positioning of Serrissinella and Dreesenulella adds to the discussion about the palaeobathymetry of the Baelen mud mounds and corroborates sedimentological evidence for their relatively shallow carbonate ramp depositional setting

The Macquenoise sandstone : a suitable Lochkovian raw material for ancient millstones : quarries, properties, manufacture and distribution (Belgium-France)

International audienceSince a few years a French-Belgian team of archeologists and geologists work on the characterization of ancient quern stones and millstones (mainly from the Antique period) linked with the identification of their stratigraphical and geographical provenances.This fruitful collaboration aims at reconstructing the ancient commercial roads and economic organization of territories during that period.In addition to the better-known volcanic rocks from the Eifel area, our study revealed the frequent occurrence of particular Devonian conglomerates and sandstones from the Ardenne area, as raw materials for the manufacturing of querns and millstones. The latter sandstones as well as the related antique millstone quarries, form an important and until now undervalued geological and cultural heritage in Belgium.Near the Ardenne border between France and Belgium, the earliest Devonian (Lochkovian) sediments deposited on the Caledonian substrate are conglomerates, which are interpreted as continental alluvial fans. The first marine sediments are littoral sandstones/quartzites or shales/slates. A sandstone formation, formally defined as the “Arkose d’Haybes” is closely linked to the former Lochkovian conglomerates (called also the “Poudingue de Fépin”). The outcrops of this particular formation around the reference localities of Haybes, Fépin and Hargnies (Ardennes, France), show a partly recrystallized, well-sorted grey to greenish sandstone (turbidite facies) with wine-red coloured joints. Another important area displaying old quarries in the same formation is located between Hirson (Aisne, France) and Macquenoise (Hainaut, Belgium): here, a more homogenous grey coarse sandstone facies occurs, with a better consistency and small amounts of dark green tourmaline crystals.These detrital formations were locally quarried, not only for building stones but also for the production of querns and millstones. The huge Proto-historical and Roman millstone quarries in Lochkovian conglomerates and sandstones from Macquenoise are known since the 19th century. Even if the lack of recent archeological excavations do not allow yet to precise the exact age of their quarrying, the dating of the various products derived from these quarries allow to consider the duration of the active extraction and how far the millstones from Macquenoise area were transported into the northern Gallo-Roman provinces

The red marble from Baelen, a geological misfit

peer reviewedHet Rode Marmer van Baelen is een crinoïdenrijke kalksteen uit het jongste Devoon (Boven-Famenniaan) van België, die dagzoomt niet al te ver onder de grens van Nederlands Zuid-Limburg. Deze bouwsteen is geologisch uniek omdat het gesteente waaruit hij werd gewonnen allicht wereldwijd het best gedocumenteerde (en misschien het enige) voorbeeld is van een z.g. bioherm of kalkslibheuvel (“mud mound”) tijdens het Famenniaan. Het calciumcarbonaat in dergelijke kalkslibheuvels is grotendeels van microbiële oorsprong, evenals het ijzerrijke pigment (hematiet) dat de vaak opvallende roze en rode kleuren veroorzaakt

An Exceptional Lower Carboniferous Historical Heritage Stone from Belgium, the ‘Pierre de Meuse’

peer reviewe

The macquenoise sandstone (Devonian – Lochkovian), a suitable raw material for ancient querns and millstones : quarries, properties, manufacture and distribution in France and Belgium

For some years, a French-Belgian team of archaeologists and geologists is investigating the provenance of ancient quern-stones and millstones. Their study revealed the frequent occurrence of particular coarse sandstones derived from Lower Devonian strata in the Ardenne region, known as either the “Arkose of Haybes” by geologists or the “Arkose of Macquenoise” by archaeologists. Material for Late Iron Age and Roman quern-stones and millstones was quarried from open pits located west of the border between France and Belgium, between the Belgian village of Macquenoise (Commune of Momignies, Province of Hainaut) and the French town of Hirson (Aisne Department, Hauts-de-France region). This paper describes the raw materials, presents the different types of grindstones produced through historical times and provides a detailed diffusion map of the millstones

Querns and mills during Roman times at the northern frontier of the Roman Empire (Belgium, Northern France, Southern Netherlands, Western Germany): Unraveling geological and geographical provenances, a multidisciplinary research project

This paper presents the results of a multi-disciplinary provenance study of querns and millstones during the Roman period (1st-4th century CE) in the northern part of the Roman Empire (provinces of Gallia Belgica and Germania Inferior). Comparative petrographical, mineralogical and geochemical analysis allowed an international team of archaeologists and geologists to identify the different raw materials used for the manufacturing of querns and millstones. As a result, (litho-) stratigraphic assignments as well as geological-geographical provenances are suggested or corroborated for the broad spectrum of these natural geo-materials. We give evidence for the exploitation of at least seven different rock types. They include sedimentary rocks (fine- to coarse-grained quartzitic and arkosic sandstones, conglomerates, limestones) and volcanic rocks (vesicular lavas) derived from different geological strata in the following geological-geographical settings: the volcanic Eifel area (Pleistocene lava), the Ardennes Massif (Palaeozoic sedimentary rocks) and the Paris and Northern Sea Basin (Cenozoic sedimentary rocks). Furthermore we show that a large diversity existed within different productions (different types of hand-mills and mechanical powered mills) and distribution patterns. This paper provides new data which will lead to new insights into the socio-economics of the local “Gallo-Roman” communities and into their networks within the northern Roman Empire