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Deze samenvatting is niet beschikbaar in het Nederlands. Abstract New Campanian to Danian dinoflagellate cyst zonation in the North and East of Belgiurn and the South-East of the Netherlands. The palynological study of 75 samples from Campanian to Danian chalks in the Hallembaye quarry, the Turnhout borehole (Belgium), and in the Beutenaken quarry (the Netherlands) shows that the material is weIl preserved and exceptionally rich in species and specimens, and provides a high biostratigraphic resolution. These deposits were subdivided in nine interval-zones, eleven subzones and four zonules. Among them eight zones, ten subzones and two zonules are newly defined below the Danea californica Zone. In stratigraphical ascending order are found: the Zone A of the Lower Campanian, followed by the Xenascus wetzelii, Areoligera coronata and Samlandia mayii zones of the Upper Campanian, the Membranilarnacia liradiscoides, Pervosphaeridium tubuloaculeatum, Deflandrea galeata and Hystrichostrogylon coninckii zones of the Maastrichtian and the Danea californica Zone of the Danian. The X. wetzelii Zone is subdivided in the Exochosphaeridium? masurii and Hystrichokolpoma gamospina subzones. The E? masurii Zone it self is subdivided in two zonules (a and b). The Membranilarnacia liradiscoides Zone is subdivided in the Alterbidinium varium and Cladopyxidium paucireticulatum subzones. The P. tubuloaculeatum, D. galeata and H. coninckii zones both are subdivided in two subzones a and b. Résumé Nouvelle zonation aux kystes de dinoflagellés du Campanien au Danien dans le nord et l'est de la Belgique et dans le sud-est des Pays-Bas. L'étude palynologique de 75 échantillons de la Craie du Campanien au Danien dans la carrière de Hallembaye et dans le sondage de Turnhout (Belgique), ainsi que dans la carrière de Beutenaken (Pays-Bas), montre que le matériel est généralement bien conservé et exceptionnellement riche en espèces et individus permettant une haute résolution biostratigraphique. Nous avons subdivisé ces dépôts en neuf interval-zones, onze subzones et quatre zonules. Parmi elles huit zones, dix subzones et deux zonules sont nouvelles et définies au-dessous de la Zone à Danea californica. Dans l'ordre stratigraphique ascendant on trouve: la Zone A du Campanien inférieur, suivie des zones à Xenascu wetzelii, à Areoligera coronata et à Samlandia mayii du Campanien supérieur, des zones à Membranilarnacia liradiscoides, à Pervosphaeridium tubuloaculeatum, à Deflandrea galeata et à Hystrichostrogylon coninckii du Maastrichtien et de la Zone à Danea californica du Danien. La Zone à X. wetzelii est subdivisée en subzones à Exochosphaeridium ? masurii et à Hystrichokolpoma gamospina. La Subzone à E. ? masurii est subdivisée à son tour en deux zonules (a et b). La Zone à M. liradiscoides est subdivisée en subzones à Alterbidinium varium et à Cladopyxidium paucireticulatum. Chacune des trois zones à P. tubuloaculeatum, à D. galeata et à H. coninckii est subdivisée en deux subzones a et b.

Deze samenvatting is niet beschikbaar in het Nederlands. Abstract A new microvertebrate fauna from the Middle Hettangian (early Jurassic) of Fontenoille (Province of Luxembourg, south Belgium). A Lower Jurassic horizon from Fontenoille yielding fossil fish remains can be dated to the Middle Hettangian Liasicus zone on the basis of the early belemnite Schwegleria and the ammonite Alsatites laqueus francus. Hybodontiform sharks are represented by Hybodus reticulatus Lissodus sp., Polyacrodus sp, and Neoselachians by Synechodus paludinensis nov. sp. and Synechodus streitzi, nov. sp. Earlier reports of a scyliorhinid are not confirmed: teeth of similar morphology to scyliorhinids seem to be juvenile variants of S. paludinensis. Chimaeriform remains include Squaloraja sp., the earliest occurrence of the genus. The Actinopterygian fauna is introduced, comprising a palaeonisciform cf. Ptycholepis, a possible late perleidiform cf. Platysiagum, the dapediid semionotiforms Dapedium and cf. Tetragonolepis, the pycnodontiform Eomesodon, halecomorphs cf. Furidae or Ophiopsidae, pholidophoriforms and/or Leptolepididae, and actinistians. Lepidosaur remains are also present. Résumé Une nouvelle faune de microvertébrés de l'Hettangien moyen (Jurassique inférieur) de Fontenoille (Province de Luxembourg, Belgique méridionale). Le gisement hettangien de Fontenoille a fourni les bélemnites précoces Schwegleria et l'ammonite Alsatites laqueus francus, permettant de l'attribuer à la zone à Liasicus de l'Hettangien moyen. Les Hybodontiformes sont représentés par Hybodus cf. reticulatus, Lissodus sp, Polyacrodus sp, les Néosélaciens Synechodus paludinensis nov. sp. et Synechodus streitzi nov. sp. ; les Scyliorhinidae originellement signalés ne sont pas confirmés, mais on considère la morphologie scyliorhinide comme une variante juvénile possible de l'espèce S. paludinensis. Les chimères sont également présentes avec Squaloraja sp, l'occurrence la plus ancienne du genre. La faune d'Actinoptérygiens est brièvement présentée, comprenant un palaeonisciforme cf. Ptycholepis, un possible perléidiforme tardif cf. Platysiagum, des sémionotiformes Dapediidae Dapedium et cf. Tetragonolepis, le pycnodontiforme Eomesodon, des Halecomorphi cf. Furidae ou Ophiopsidae, des pholidophoriformes et/ou des Leptolepididae, ainsi qu' un Actinistia. On relève également la présence d'un reptile lépidosaure.

Ce résumé n'est disponible qu'en anglais. Deze samenvatting is alleen beschikbaar in het Engels. Abstract The Brabant Massif is the largest Lower Palaeozoic unit of Belgium, only exposed at its southern part along a few river incisions. The outcrops at Halle-Lembeek, located 20 km SW of Brussels, form the northern part of the Zenne outcrop area. Widening of the railway track Lille-Brussels offered a rare opportunity to study this area in more detail. Temporary outcrops and cored drillings provided a discontinuous lithostratigraphic log of the middle part of the Lower Cambrian Tubize Formation. Lithology and analysis of turbidite sequences show the transition of the relatively well-known Rogissart Member, characterised by proximal and thick turbidites, to the poorly documented lowermost and currently unnamed member of the Tubize Formation, which is characterised by a more distal facies. A magmatic body in one of the permanent outcrops crosscuts the host-rock and is therefore of intrusive nature. Amygdules and vesicles in nearby decimetric magmatic interstratifications indicate volcanic activity in the Lower Cambrian. The intrusive and volcanic rocks have a similar chemistry, suggesting a relation to one episode of, previously unrecognised, Lower Cambrian magmatism. Logging with a magnetic pendulum shows that younger rocks in the southern outcrops are more magnetic than older rocks in the northern outcrops. This trend corresponds to an increase in aeromagnetic field values from north to south. Outcrops of the non-magnetic rocks of the Blanmont Formation, northeast of Halle-Lembeek, correspond to well delimited aeromagnetic trough anomalies. Folds occur at two locations in Halle-Lembeek. Near Lembeek a fold train of three steeply plunging anticlines and three synclines with divergent cleavage fans, is found. North and south of this fold train, non-folded, steeply dipping beds are found that are younging towards the SW and WSW respectively, and show a counterclockwise cleavage to bedding relation. In the northern outcrops near Halle, tight, gently plunging folds and open, steeply plunging folds are found. The relation between lithostratigraphy and aeromagnetism allows defining the distribution of lithostratigraphic units around Halle-Lembeek. However, several interpretations are possible of the nature of the contacts between different lithostratigraphic units and of aeromagnetic anomalies. Three models are therefore proposed, assuming respectively isoclinal folding, steep shear zones, and absence of folds or shear zones. Also combinations of the three models are possible.

This summary is not available in Dutch. Abstract Tectonics of the variscan front in the provinces of Hainaut and Namur (South Belgium). The coal fields of the Hainaut and Namur Provinces are made up of 2 distinctive tectonic units. The upper unit stretches from Douai in the West to Huy in the East and comprises the Denain massifs, which stretch from France into Belgium and become the massif of Masse, followed by the massifs of Chamborgneau, Ormont and Malonne. It is shown that these massifs, though slightly separated one from the other, form actually one big massif, which was named "Great Superficial Massif". It lies on a parautochtonous unit made up of an imbricate fan, which is separated by inverse faults of easily determinable throws. The sole fault that separates those 2 units was called "Great Hainaut fault". It passes over a footwall of cataclastic rocks. For a long time, it has been called "faulted zone" or even "overthrust sheet". However, in our opinion this zone represents the surface of a fossil peneplain. Indeed, no Westphalian C is known in the parautochtonous massifs. Therefore, erosion and peneplanation must have taken place before the emplacement of the "Great superficial massif". The "Great superficial massif" is made up of Westphalian C, B and A, of Namurian, Dinantian, upper and middle Devonian, Silurian and Ordovician formations. This "Great superficial massif" originated from the North and was originally deposited on the Brabant massif. From there, it underwent a gravitational slip into the "Flenu trough" and covered the parautochtonous unit. It was then in turn partly overthrusted by the Midi massif set in motion towards the North. This slip into the Flenu trough is caused, on the one hand by the uplift of the Brabant massif and on the other hand by the dissolution of evaporites in the deeply buried Dinantian. The latter must have contained halite as shown by the brecciated anhydrite, indicative for early collapse. This explains why the "Great superficial massif" does not include lower Devonian formations and that the coals have not evolved much as they have not undergone any deep burial. The sole fault of the "Great superficial massif" seems linked to the Midi fault. One must write "seems" since the intersection between both faults is not exposed as the coal mining kept a distance from this intersection. However, one can reasonably locate it between the overturned strata, which characterise the southern front of the "Great superficial massif" and the moderately dipping strata of the parautochtonous massifs. Résumé Les bassins houillers du Hainaut et du Namurois sont constitués par deux entités tectoniques bien distinctes. L'entité supérieure s'étend de Douai à Huy; elle comprend les massifs dits de Denain (lequel se poursuit en Belgique par le massif de Masse), le massif de Chamborgneau, le massif d'Ormont et le massif de Malonne. Ces massifs légèrement déboîtés l'un par rapport à l'autre n'en font, en réalité, qu'un seul que j'ai nommé "Grand massif superficiel". Ce massif repose sur la seconde entité tectonique parautochtone constitué d'une série d'écailles tectoniques séparées par des failles inverses de rejets connus. La faille qui sépare ces deux entités et qu'on pourrait appeler "Grande faille du Hainaut" correspond à un horizon intensément tectonisé. Celui-ci, connu depuis longtemps sous le nom de "zone failleuse" ou, mieux, sous le nom de "nappe faillée", représente la surface d'une pénéplaine fossile. En effet, le Westphalien C n'a pas été observé au sein des massifs parautochtones. Par conséquence, la mise en place du "Grand massif superficiel" a eu lieu après l'érosion et la pénéplanation. Le "Grand massif superficiel" est constitué de Westphalien C, B et A, de Namurien, de Dinantien, de Dévonien supérieur et moyen, de Silurien et d'Ordovicien. Ce "Grand massif superficiel" provient du nord, c'est-à-dire du massif du Brabant, sur lequel il s'était déposé; de là, il a glissé gravitairement dans l'auge du Flénu en couvrant l'entité parautochtone, puis a été recouvert à son tour et en partie par le massif du Midi mis en mouvement vers le nord. Ce glissement dans l'auge du Flénu est dû, d'une part au relèvement du massif du Brabant, et d'autre part à la dissolution en profondeur des évaporites du Dinantien, lequel devait comporter de la halite, puisque actuellement l'anhydrite se trouve en brèche, indiquant un premier effondrement (collapse). C'est ainsi que le "Grand massif superficiel" ne renferme pas de Dévonien inférieur et que les houilles y sont peu évoluées, puisque n'ayant subi aucun enfouissement. La faille sous-jacente du "Grand massif superficiel" semble joindre la faille du Midi vers le Sud. S'il faut écrire "semble", c'est parce que l'intersection entre les deux n'est pas connue car éloignée de toute exploitation minière. On peut cependant la situer raisonnablement entre les dressants renversés et les plateures qui caractérisent respectivement le sud du "Grand massif superficiel" et les massifs subautochtones.

A 302 m deep, cored reconnaissance well was drilled in 1980, at Jagersborg to the northwest of Maaseik (49W0220). The borehole is located north of the Feldbiss fault system, in the Rur Valley Graben. The top of the section consists of Saalian to Pleni-Weichselian Meuse gravels capped by loam. The section between 22 and 193 m is identified as the Kieseloolith Formation, consisting mainly of quartzic sands with the intercalation of four lignite and clay intervals. Lithological characteristics and geophysical well logs allow the traditional identification of the Waubach sands and gravels at the base of the Kieseloolith Formation, overlain by the Pey sands between two lignite and clay levels which are interpreted as Brunssum clay; using the same approach, the sands above the upper Brunssum clay are interpreted as the Schinveld/Jagersborg sands. The palynology, however, suggests a Pliocene age, Reuverian, for the entire quartz sand unit although also a Brunssum age could be accorded to the quartz sand below 90 m depth. Two palynozones occur with a boundary around 57.6 m. The top of the lower palynozone A, between 57.6 and 87.5 m, has a similar composition as the Mol sand lignites occurring to the west, outside the Rur Valley Graben. The upper palynozone B between 57.6 m and the top of the sands characterizes the Reuverian C and the clay layers present in this section are consequently interpreted as Reuver clay. The palynozone A represents a landscape covered by dense forest in contrast to the upper palynozone B during which the clearance of the woods had already started, the forest became less dense and enclosed mires more extensive. The top of the Kieseloolith Formation marks the transition to the Praetiglian. All lignites show a rank between the brown coals in the Lower-Rhine exploitations and peats. The interval between 193 and 198 m is a yellow quartzic, mica-containing marine sand of uncertain stratigraphic position; it might correspond to the Syltian, an uppermost Miocene regional North-Sea stage. The green glauconitic sands between 198 and 302 m are identified as the Breda Formation and can be further subdivided based on grain size and glauconite content. Dinofl agellates and mollusc fragments allow the identification of a lower part between 302 and about 273 m that is biostratigraphically similar to the upper part of the Antwerpen Member and Zonderschot Member of the Berchem Formation to the west. It is considered as Middle Serravallian in age based on dinofl agellates. An upper part between about 235 and 198 m is biostratigraphically equivalent to the Deurne and Dessel Members of the Diest Formation, based on dinofl agellates, molluscs, benthic foraminifera and ostracods. The age of this upper part is Tortonian. The interval between these lower and upper parts of the Breda Formation has no facies equivalents in the Campine basin to the west.

The famous "boudins" from the Ardenne and Eifel regions (Belgium, Germany) occur as regularly-spaced segments of Lower Devonian (meta-)sandstones separated by lens-shaped quartz veins. The whole is embedded in thick siltstone or shale horizons. Structural evidence throughout the Ardenne-Eifel region reveals a two-stage deformation sequence composed of a layer-parallel extension followed by a layer-parallel shortening. The latter results from the development of the Rhenohercynian fold-and-thrust belt during the Variscan orogeny (Carboniferous). During that period, the boudins inherited from the layer-parallel extension were strongly reworked and acquired their current extreme convex geometry, in parallel to a reduction of the aspect ratio (width/height) to ~0.5. We consider therefore that these structures should be named as ‘narrow reworked boudins’. The prefix ‘narrow’ indicates that before the reworking period the boudin aspect ratio was already small (~ 1.0). In this memoir, evidences of unquestionable narrow boudins are illustrated. Their formation results from the opening of a joint set at a fracture saturation stage, in which any additional layer-parallel extension is accommodated by the opening of the existing joints instead of the development of new joints. We present a new model including all these aspects for the formation and reworking of boudins as those from the Ardenne-Eifel region. The Lower Devonian formations from the Ardenne-Eifel region include not only thick siltstone or shale horizons with isolated sandstone layers that were boudinaged and then reworked, but also sandstone-dominant to massive sandstone units, where fine materials represent only cm- to mm-interlayers. Their deformation patterns differ from those richer in fine materials. During the period of layer-parallel extension, both sandstone-dominant and massive sandstone successions were affected by the growth of complex arrays of single- and multi-layered quartz veins. Single-layered veins correspond to pure open-mode fractures, while multi-layered veins frequently represent a hybrid-shear fracturation mode. During the layer-parallel shortening period, small-scale folds were developed in the sandstone-dominant units in close association with the occurrence of multi-layered quartz veins. By contrast, the quartz veins in massive sandstone units seem to have no influence during the layer-parallel shortening period. In this case, the shortening was accommodated by common structures, such as large-scale folds and reverse faulting (ramp).

The present memoir has two main aims: to document the work done in gravimetric data acquisition in Belgium, going back to the nineteenth century, and to calculate and discuss a new Bouguer anomaly map based on a novel approach with a varying reduction density. Gravity measurements have three main applications: metrology (to locally calibrate instruments such as balances), geology (to understand the local subsoil at varying depths), and geodesy. The first heading of the memoir places the Belgian part of the geoid in the framework of a general presentation of the world geoid. It is used to locate oneself with GPS in altitude with a precision of 2 cm, the Belgian geoid being one of the most detailed in the world because of the very high gravity coverage. Some theoretical considerations concerning gravity measurement, and the realisation of modern networks, are presented in the second and third headings respectively. Since geological interpretation of the Bouguer anomaly map is the main concern of the geological community, the fourth heading gives an overview of the history of gravity acquisition in Belgium and the related evolution of the Bouguer map, giving some short biographical notes about scientists who intensively participated in the gravity acquisition. The fifth heading discusses the development of a new Bouguer map calculated with varying reduction density, adapted to the Belgian subsoil. To reach this goal it was necessary to make use of the bathymetric map of the Palaeozoic and the topographic map of the younger unconsolidated cover rocks. The last heading is concerned with the geological interpretation of the spatial variation of gravity in Belgium, and discusses both the existing scientific literature and the peculiarities of the new Bouguer anomaly map produced in 2011 (this work). Résumé Ce mémoire a deux objectifs principaux: d’une part documenter le travail réalisé pour l’acquisition des données gravimétriques belges de terrain depuis le XIXe siècle, et d’autre part la réalisation d’une nouvelle carte de Bouguer calculée avec une densité de réduction variable. La gravimétrie a trois principaux domaines d’application : la métrologie (pour la calibration locale d’appareils tels que des balances), la géologie (pour comprendre le sous-sol local à différentes profondeurs) et la géodésie. Dans le premier chapitre de ce mémoire, nous présentons le géoïde de Belgique dans le cadre du géoïde mondial. Celui-ci est utilisé pour se positionner en altitude avec les GPS avec une précision de 2 cm ; en Belgique, il est un des meilleurs du monde grâce à la grande densité de la couverture gravimétrique belge. Les deuxième et troisième chapitres présentent des considérations théoriques sur la gravimétrie et la manière de réaliser des réseaux modernes. Comme l’interprétation géologique de la carte de Bouguer est une préoccupation majeure de la communauté géologique, nous présentons dans le quatrième chapitre un historique des mesures gravimétriques en Belgique, l’évolution de la carte de Bouguer dans le temps, ainsi que des courtes notes biographiques sur les personnes intensivement impliquées dans l’acquisition des données de terrain. Le cinquième chapitre expose ce qui a été mis en oeuvre pour réaliser une carte de Bouguer avec une densité de réduction variable. Pour atteindre ce but, il a été nécessaire d’impliquer dans les calculs la carte bathymétrique du Paléozoïque et la carte topographique de la couverture plus jeune. Le dernier chapitre est consacré à l’interprétation géologique de la carte de Bouguer belge, et inclut une revue de la littérature scientifique ainsi que l’interprétation des caractéristiques de la nouvelle carte de 2011 (ce travail). Samenvatting In deze verhandeling worden twee hoofddoelstellingen gesteld: enerzijds het documenteren van het geleverde werk op het gebied van gravimetrische data-acquisitie in België sinds de 19e eeuw, en anderzijds het maken van een nieuwe Bouguer-kaart met een variabele reductiedichtheid. Metingen van de zwaartekracht hebben drie toepassingsdomeinen: de metrologie (voor het lokaal ijken van toestellen zoals weegschalen), de geologie (voor het begrijpen van de lokale ondergrond op verschillende diepte) en de geodesie. Onder de eerste hoofding van deze verhandeling wordt het Belgische deel van de geoïde geplaatst binnen een algemene voorstelling van de globale geoïde. Deze wordt gebruikt om zich met GPS met een precisie van 2 cm te positioneren in de hoogte. Dit is één van de meest gedetailleerde modellen ter wereld gezien de zeer hoge densiteit van de gravimetrische bedekking van België. De tweede en derde hoofdstukken handelen over theoretische overwegingen betreffende zwaartekrachtmetingen, en over de wijze waarop moderne netwerken gerealiseerd worden. Aangezien de geologische interpretatie van de Bouguer-kaart steeds de belangrijkste bekommernis is van de geologische gemeenschap, wordt in het vierde hoofdstuk een overzicht gegeven van de geschiedenis van de gravimetrische metingen in België, en de daaraan gekoppelde evolutie van de Bouguer-kaart, met enkele korte biografische nota’s over personen die intensief deelgenomen hebben aan acquisitie van terreingegevens. Het vijfde hoofdstuk behandelt het opstellen van een nieuwe Bouguer-kaart met variabele reductiedichtheid, aangepast aan de specifieke Belgische ondergrond. Hiervoor was het noodzakelijk om een bathymetrische kaart van het Paleozoïcum en een topografische kaart van de jongere afdekkende lagen te betrekken bij de berekeningen. Het laatste hoofdstuk is gewijd aan de geologische interpretatie van de ruimtelijke variatie van de zwaartekracht in België, en behandelt zowel de bestaande wetenschappelijke literatuur als de kenmerken zichtbaar op de nieuwe kaart van de Bouguer-anomalie anno 2011 (dit werk).

This field guide gives an insight into the Lower Palaeozoic geology of the Geete outcrop area in the surroundings of Jodoigne. Five selected outcrops or groups of outcrops are visited. These are the northern Dongelberg Quarry at Dongelberg, the Les Fosses Quarry at Opprebais (Incourt), outcrops along the Rue du Maka at Jauchelette, outcrops along the Rue du Vieux Moulin at Jodoigne and the outcrop below the town hall at Jodoigne. In each case, a detailed description is provided of the lithology, lithostratigraphy and structural architecture, followed by remarks and interpretation. The geological observations from these field trip stops are used to illustrate lithological differences between the Blanmont Formation and the different facies of the Jodoigne Formation, to demonstrate the presence of steeply plunging and gently plunging folds, to illustrate the common occurrence of pre-cleavage folds, interpreted as slump folds, and to outline our arguments for the newly proposed stratigraphic position of the Jodoigne Formation. The cartographic proximity of the Lower Cambrian Blanmont Formation and the Middle to Upper Cambrian Jodoigne Formation is explained by means of the Asquempont Detachment System. The observations and their implications are placed in the broader context of the Belgian Lower Palaeozoic.