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Article Reference The complexity of 3D stress-state changes during compressional tectonic inversion at the onset of orogeny
Compressional tectonic inversions are classically represented in 2D brittle failure mode (BFM) plots that illustrate the change in differential stress (σ1−σ3) versus the pore-fluid pressure during orogenic shortening. In these BFM plots, the tectonic switch between extension and compression occurs at a differential stress state of zero. However, mostly anisotropic conditions are present in the Earth's crust, making isotropic stress conditions highly questionable. In this study, theoretical 3D stress-state reconstructions are proposed to illustrate the complexity of triaxial stress transitions during compressional inversion of Andersonian stress regimes. These reconstructions are based on successive late burial and early tectonic quartz veins which reflect early Variscan tectonic inversion in the Rhenohercynian foreland fold-and-thrust belt (High-Ardenne Slate Belt, Belgium, Germany). This theoretical exercise predicts that, no matter the geometry of the basin or the orientation of shortening, a transitional ‘wrench’ tectonic regime should always occur between extension and compression. To date, this intermediate regime has never been observed in structures in a shortened basin affected by tectonic inversion. Our study implies that stress transitions are therefore more complex than classically represented in 2D. Ideally, a transitional ‘wrench’ regime should be implemented in BFM plots at the switch between the extensional and compressional regimes.
Located in Library / No RBINS Staff publications
Article Reference The composite Kortrijk section (W Belgium): a key reference for mid-Ypresian (Early Eocene) stratigraphy in the southern North Sea Basin
The upper part of the Kortrijk Clay Formation (the Roubaix Clay and Aalbeke Clay Members of mid-Ypresian age) has been exposed in road and canal cuttings and clay quarries in the Kortrijk area (western Belgium), and penetrated by several cored boreholes. It is overlain disconformably by the Mont-Panisel Sand Member of the Hyon Sand Formation (upper middle Ypresian). The Roubaix Clay Member contains diverse and well-preserved calcareous nannofossils, dinoflagellate cysts, foraminifera, ostracods and other calcitic microfossils, and less well-preserved mollusc assemblages, while the Aalbeke Clay Member is secondarily decalcified. The calcareous nannofossil subdivision of upper NP11 and lower NP12 has been recognised in the Kortrijk area, and calibrated with the NW European mid-Ypresian dinoflagellate cyst, ostracod and planktonic foraminiferal zones and datums (e.g. Subbotina influx). Several medium-scale depositional sequences, with an estimated duration of 400 kyr or less, have been recorded. Their respective boundaries coincide with the resistivity maxima identified on the majority of the wireline log profiles of the Belgian Ypresian. Integrated biostratigraphic, magnetostratigraphic and sequence stratigraphic analysis enables correlation with other areas in Belgium, with the London Clay Formation of southern England, and with the standard chronostratigraphic scale. A marine erosion surface has been identified at the base of Unit 20 in the Kortrijk area (mid-Ypresian, early Biochron NP12, middle C24n.1n, ~ 52.8 Ma), corresponding to the first occurrence of estuarine channel-fill units in southern England. This indicates a brief but profound sea-level fall, either eustatically or tectonically controlled. The composite Kortrijk section is proposed as a reference section for the middle Ypresian in the southern North Sea Basin, and for similar settings in mid- to high-latitudes of the Northern Hemisphere (e.g. Kazakhstan and Crimea).
Located in Library / RBINS Staff Publications 2017
Article Reference The composite Kortrijk section (W Belgium): a key reference for mid-Ypresian (Early Eocene) stratigraphy in the southern North Sea Basin.
The upper part of the Kortrijk Clay Formation (the Roubaix Clay and Aalbeke Clay Members of mid-Ypresian age) has been exposed in road and canal cuttings and clay quarries in the Kortrijk area (western Belgium), and penetrated by several cored boreholes. It is overlain disconformably by the Mont-Panisel Sand Member of the Hyon Sand Formation (upper middle Ypresian). The Roubaix Clay Member contains diverse and well-preserved calcareous nannofossils, dinoflagellate cysts, foraminifera, ostracods and other calcitic microfossils, and less well-preserved mollusc assemblages, while the Aalbeke Clay Member is secondarily decalcified. The calcareous nannofossil subdivision of upper NP11 and lower NP12 has been recognised in the Kortrijk area, and calibrated with the NW European mid-Ypresian dinoflagellate cyst, ostracod and planktonic foraminiferal zones and datums (e.g. Subbotina influx). Several medium-scale depositional sequences, with an estimated duration of 400 kyr or less, have been recorded. Their respective boundaries coincide with the resistivity maxima identified on the majority of the wireline log profiles of the Belgian Ypresian. Integrated biostratigraphic, magnetostratigraphic and sequence stratigraphic analysis enables correlation with other areas in Belgium, with the London Clay Formation of southern England, and with the standard chronostratigraphic scale. A marine erosion surface has been identified at the base of Unit 20 in the Kortrijk area (mid-Ypresian, early Biochron NP12, middle C24n.1n, ~ 52.8 Ma), corresponding to the first occurrence of estuarine channel-fill units in southern England. This indicates a brief but profound sea-level fall, either eustatically or tectonically controlled. The composite Kortrijk section is proposed as a reference section for the middle Ypresian in the southern North Sea Basin, and for similar settings in mid- to high-latitudes of the Northern Hemisphere (e.g. Kazakhstan and Crimea).
Located in Library / RBINS Staff Publications 2017
Article Reference The contribution if Jan H. Stock to the origin and biodiversity of subterranean aquatic crustaceans (an introduction to the Jan H. Stock memorial Syposium's theme)
Located in Library / RBINS Staff Publications
Article Reference The Cordex.be initiative as a foundation for climate services in Belgium
Located in Library / RBINS Staff Publications 2018
Article Reference The creodonts (mammalia, Ferae) from the Paleocene-Eocene transition in Belgium (Tienen Formation, MP7)
Study of the dental remains of creodont mammals from the Paleocene-Eocene transition in Belgium (Tienen Formation, reference-level MP7) allows seven species to be recognized, four of which belong to the family Hyaenodontidae and three to the Oxyaenidae. The four hyaenodontid species, which are new to science, present numerous symplesiomorphic characteristics. They represent the oldest hyaenodontids of northern Europe and are shown to be the most primitive representatives of the sub-family Hyaenodontinae known so far. They are closely related to the oldest North American species but the morphological differences between them demonstrate that they are not vicariant species. Thus, the Belgian species could be at the origin of the American hyaenodontid lineages or belong to lineages already distinct but recently differentiated from common ancestors slightly older than both of these species groups. As for oxyaenids, their dental morphology shows that they could originate from the North American Paleocene lineages, although their small size does not support this hypothesis. The smallest Belgian creodont, Prototomus minimus n. sp. is remarkable in that it may present sexual dimorphism in mandibular morphology.
Located in Library / RBINS Staff Publications
Article Reference The Dababiya Corehole, Upper Nile Valley, Egypt: Preliminary results.
The Dababiya corehole was drilled in the Dababiya Quarry (Upper Nile Valley, Egypt), adjacent to the GSSP for the Paleocene/ Eocene boundary, to a total depth of 140 m and bottomed in the lower Maastrichtian Globotruncana aegyptiaca Zone of the Dakhla Shale Formation. Preliminary integrated studies on calcareous plankton (foraminifera, nannoplankton), benthic foraminifera, dinoflagellates, ammonites, geochemistry, clay mineralogy and geophysical logging indicate that: 1) The K/P boundary lies between 80.4 and 80.2 m, the Danian/Selandian boundary between ~ 41 and 43 m, the Selandian/Thanetian boundary at ~ 30 m (within the mid-part of the Tarawan Chalk) and the Paleocene/Eocene boundary at 11.75 m (base [planktonic foraminifera] Zone E1 and [calcareous nannoplankton] Zone NP9b); 2) the Dababiya Quarry Member (=Paleocene/Eocene Thermal Maximum interval) extends from 11.75 to 9.5 m, which is ~1 m less than in the adjacent GSSP outcrop.; 3) the Late Cretaceous (Maastrichtian) depositional environment was nearshore, tropical-sub tropical and nutrient rich; the latest Maastrichtian somewhat more restricted (coastal); and the early Danian cooler, low(er) salinity with increasing warmth and depth of water (i.e., more open water); 4) the Paleocene is further characterized by outer shelf (~ 200 m), warm water environments as supported by foraminifera P/B ratios > 85% (~79-28 m), whereas benthic foraminifera dominate (>70%) from ~27-12 m (Tarawan Chalk and Hanadi Member) due, perhaps, in part to increased dissolution (as observed in nearby outcrop samples over this interval); 5) during the PETM, enhanced hydrodynamic conditions are inferred to have occurred on the sea-floor with increased river discharge (in agreement with sedimentologic evidence), itself a likely cause for very high enhanced biological productivity on the epicontinental shelf of Egypt; 6) correlation of in situ measured geophysical logs of Natural Gamma Ray (GR), Single-Point Resistance (PR), Self-Potential (SP), magnetic susceptibility(MS), and Resistivity, and Short Normal (SN) and Long Normal (LN) showed correspondence to the lithologic units. The Dababiya Quarry Member, in particular, is characterized by very high Gamma Ray and Resistivity Short Normal values.
Located in Library / RBINS Staff Publications
Article Reference The Dababiya Quarry section: lithostratigraphy, clay mineralogy, geochemistry and paleontology.
Located in Library / RBINS Staff Publications
Article Reference The DeepMIP contribution to PMIP4: methodologies for selection, compilation and analysis of latest Paleocene and early Eocene climate proxy data, incorporating version 0.1 of the DeepMIP database.
Located in Library / RBINS Staff Publications 2019
Article Reference The delusion of stripes: A century-old mystery of five-lined sun skinks (Reptilia: Scincidae: Eutropis) of Peninsular India elucidated
We re-evaluate the taxonomic identities of five-lined skinks of the genus Eutropis (E. trivittata, E. beddomei, E. nagarjunensis, and E. bibronii) inhabiting the Indian subcontinent. Previously it has been considered that E. trivittata is distributed in the western India and E. dissimilis in the northern India (from north-eastern India up to Pakistan). Based on our analysis, we revealed that the illustration (iconotype) of the untraceable type specimen of E. trivittata depicted by Hardwicke in Gray (1834) from “Dumdum” near Kolkata, West Bengal matches the typical E. dissimilis, also described from “Bengal”. The senior synonym, E. trivittata is a morphologically unique species, which is also supported by divergence in the mitochondrial 12S and 16S regions. E. trivittata is clearly separated with divergences of 5–7% from E. beddomei, E. vertebralis and E. nagarjunensis for 16S rRNA. After placing E. dissimilis with the synonymy of E. trivittata, the taxonomic status of the western Indian ‘E. trivittata’ required to be clarified. Therefore, we resurrect Mabuia vertebralis Boulenger, 1887, a junior synonym of western Indian E. trivittata, and redescribe its holotype collected from “Belgaum”, Karnataka. Although, morphologically closest to E. beddomei, Eutropis vertebralis comb. nov. is sister to E. nagarjunensis with divergence of 4% in the same mitochondrial regions. Based on our update of the currently confirmed localities for E. vertebralis comb. nov. and E. trivittata, we conducted Species Distribution Modelling (SDM) using the Maximum Entropy algorithm to predict its distribution range, and we discuss its conservation status.
Located in Library / RBINS Staff Publications 2021