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Seismotectonic significance of the 2008-2010 Walloon Brabant seismic swarm in the Brabant Massif (Belgium)
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Between 12 July 2008 and 18 January 2010 a seismic swarm occurred close to the town of Court-Saint-Etienne, 20 km SE of Brussels (Belgium). The Belgian network and a temporary seismic network covering the epicentral area established a seismic catalogue in which magnitude varies between ML -0.7 and ML 3.2. Based on waveform cross-correlation of co-located earthquakes, the spatial distribution of the hypocentre locations was improved considerably and shows a dense cluster displaying a 200 m-wide, 1.5-km long, NW-SE oriented fault structure at a depth range between 5 and 7 km, located in the Cambrian basement rocks of the Lower Palaeozoic Anglo-Brabant Massif. Waveform comparison of the largest events of the 2008–2010 swarm with an ML 4.0 event that occurred during swarm activity between 1953 and 1957 in the same region shows similar P- and S-wave arrivals at the Belgian Uccle seismic station. The geometry depicted by the hypocentral distribution is consistent with a nearly vertical, left-lateral strike-slip fault taking place in a current local WNW–ESE oriented local maximum horizontal stress field. To determine a relevant tectonic structure, a systematic matched filtering approach of aeromagnetic data, which can approximately locate isolated anomalies associated with hypocentral depths, has been applied. Matched filtering shows that the 2008–2010 seismic swarm occurred along a limited-sized fault which is situated in slaty, low-magnetic rocks of the Mousty Formation. The fault is bordered at both ends with obliquely oriented magnetic gradients. Whereas the NW end of the fault is structurally controlled, its SE end is controlled by a magnetic gradient representing an early-orogenic detachment fault separating the low-magnetic slaty Mousty Formation from the high-magnetic Tubize Formation. The seismic swarm is therefore interpreted as a sinistral reactivation of an inherited NW–SE oriented isolated fault in a weakened crust within the Cambrian core of the Brabant Massif.
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3D geobody reconstruction and CO2-origin of Pleistocene travertine deposits in the Ballık area (SW Turkey)
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The Denizli Basin in the West Anatolian Extensional Province in western Turkey is well-known for its numerous travertine occurrences. A combined sedimentological, diagenetic and geochemical investigation is executed on the Ece and Faber travertines of the Ballık area, the largest travertine site in the Denizli Basin. The first aim of this study is the reconstruction of a three-dimensional geo-model in combination with a detailed sedimentological description from fabric to lithotype, lithofacies and geobody scale, with a focus on integrating pore-typing. The second aim involves the delineation of the CO2-origin of ancient travertine precipitating waters. Peloidal, phyto and dendritic lithotypes dominate the studied travertines and honeycomb and bacteriform shapes and encrusted bacterial or fungal filaments related to their fabrics suggest a microbial influence. The environment of travertine precipitation evolved from dominantly sub-aqueous, as represented by the sub-horizontal and biostromal reed travertine facies, to dominantly sub-aerial in a thin water film, resulting in the cascade, waterfall and biohermal reed travertine facies. A general progradation of the travertine mound is indicated by the occurrence of stacked waterfall travertines. This results in sigmoidal clinoforms inside a general mound boundary configuration. Strontium and oxygen-carbon isotope signatures of the travertines point to a mixing mechanism of palaeofluids with deeply originated, heavy carbon CO2 with lighter carbon CO2 of shallow origin. These deposits can thus be considered as endogenic travertines. Carbonates of the Lycian Nappes acted as main parent carbon source rocks. The relative contribution of the lighter carbon isotopes is most likely to have originated from organic matter or soil CO2. This study provides a unique three-dimensional insight into the Ballık travertine architecture that potentially can be used as an analogue for subsurface travertine reservoirs worldwide and illustrates the importance of the combined use of δ13C and 87Sr/86Sr signatures in the delineation of the CO2-origin of travertine precipitating waters.
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Fracture networks and strike-slip deformation along reactivated normal faults in Quaternary travertine deposits, Denizli Basin, Western Turkey
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The Denizli Basin in the West Anatolian Extensional Province in western Turkey is known for its numerous Quaternary travertine occurrences. Travertine morphology is often dependant on the relative position of the deposition with respect to basin-bounding faults. The travertine occurrences examined in this study are situated at the intersection of the locally E–W oriented Denizli Basin and the adjacent NE–SW oriented Baklan Graben in the NE. Based on an extensive field campaign, including LIDAR scanning, several high-resolution fault/fracture maps of five large quarries (> 300 m in length and > 60 m in height) are constructed in which this world-class travertine deposit is currently excavated. A structural analysis is performed in order to determine the tectonic overprinting of the travertine body and to derive the stress states of the basin after travertine deposition. The mostly open, non-stratabound joints are several tens of metres long and often bifurcate creating a dense fracture network. Minor infill of the joints resulted in the presence of a few colour-banded calcite veins. Based on the E–W, NE–SW and NW–SE orientation of three dominant joint sets it is concluded that the joint network is caused by local N-S extension, alternated by NW–SE and NE–SW extension exemplifying the presence of stress permutations in the Quaternary. High angle E–W to WNW–ESE faults cross-cut the quarries. Faults are filled with travertine debris and clastic infill of above lying sedimentary units indicative of the open nature of the faults. The specific E–W fault orientation in the locally E–W trending Denizli Basin indicates that they initiated as normal faults. A paleostress inversion analysis performed on kinematic indicators such as striations on the clayey fault infill and the sinistral displacement of paleosols shows that some of the normal faults were reactivated causing left-lateral deformation in a transient strike–slip stress field with a NE–SW oriented σ1.
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Bistability in the redox chemistry of sediments and oceans
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For most of Earth’s history, the ocean’s interior was pervasively anoxic and showed occasional shifts in ocean redox chemistry between iron-buffered and sulfide-buffered states. These redox transitions are most often explained by large changes in external inputs, such as a strongly altered delivery of iron and sulfate to the ocean, or major shifts in marine productivity. Here, we propose that redox shifts can also arise from small perturbations that are amplified by nonlinear positive feedbacks within the internal iron and sulfur cycling of the ocean. Combining observational evidence with biogeochemical modeling, we show that both sedimentary and aquatic systems display intrinsic iron–sulfur bistability, which is tightly linked to the formation of reduced iron–sulfide minerals. The possibility of tipping points in the redox state of sediments and oceans, which allow large and nonreversible geochemical shifts to arise from relatively small changes in organic carbon input, has important implications for the interpretation of the geological rock record and the causes and consequences of major evolutionary transitions in the history of Earth’s biosphere
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RBINS Staff Publications 2020
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Cryptophyllium, the hidden leaf insects – descriptions of a new leaf insect genus and thirteen species from the former celebicum species group (Phasmatodea, Phylliidae)
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RBINS Staff Publications 2021
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Are petrous bones just a repository of ancient biomolecules? Investigating biosystematic signals in sheep petrous bones using 3D geometric morphometrics
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Over the last decade, the petrous bone (petrosum) has become the ultimate repository of ancient biomolecules, leading to a plea for a more ethical curation preventing the systematic destruction of this bioarchaeological archive. Here, we propose to explore the biosystematic signal encompassed in the biological form of 152 petrosa from modern populations of wild and domestic sheep landraces/breeds across Western Europe, South-Western Asia and Africa, using high resolution geometric morphometrics (GMM) and the latest development in 3D virtual morphology. We assessed the taxonomic signals among wild and domestic caprine species and sheep landraces. We also explored the effect of sexual dimorphism and ageing at the population scale. Finally, we assessed the influence of climatic factors across the geographic distribution of our dataset using Köppen-Geiger climate categories. We found that the 3D form of petrous bones can accurately separate wild and domestic caprine taxa and that it is not influenced by sexual dimorphism, post-natal ageing or horn bearing. Recent selective breeding has not induced sufficient diversification to allow accurate identification of the different landraces/breeds in sheep; however, both genetic distance and climatic differences across the current distribution in sheep landraces/breeds strongly contribute to petrosum intraspecific variation. Finally, human mediated dispersal of domestic sheep outside their Near Eastern cradle, especially towards Africa, have greatly contributed to the diversification of sheep petrous bone form and shape. We therefore highly recommend systematic 3D surface modelling of archaeological petrosa with preliminary GMM studies to help target and reduce destructive biomolecular studies.
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RBINS Staff Publications 2022
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Mitogenomic characterization and systematic placement of the Congo blind barb Caecobarbus geertsii (Cypriniformes: Cyprinidae)
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This study presents the first complete mitochondrial genome (mitogenome) of Caecobarbus geertsii, the Congo blind barb, a cave-dwelling, CITES-protected, cyprinid fish endemic to the Lower Congo basin (DRC). The length of the circular mitogenome is 16,565 base pairs. The 13 protein coding genes, 2 ribosomal RNA genes and 22 transfer RNA genes are similar in position and direction to those of other members of the family Cyprinidae. Phylogenetic analyses including 28 complete mitogenomes from representatives of the subfamily Smiliogastrinae (Cyprinidae), showed that Caecobarbus was nested within a clade including representatives of the genus Enteromius. The data presented in this study provide information on the molecular identification and classification of this threatened species. The results further suggest the need for a taxonomic revision of the genus Enteromius.
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RBINS Staff Publications 2020
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The introduction of the European fallow deer to the northern provinces of the Roman Empire: a multi-proxy approach to the Herstal skeleton (Belgium)
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Many exotic animal species were introduced to Northern Europe during the Roman period, including fallow deer (Dama dama). To date, however, finds of fallow deer bones at archaeological sites in this region have been sporadic and disarticulated, leaving uncertainty over their origins. This article presents the first known articulated fallow deer skeleton from Roman North-western Europe. Osteological, ancient DNA, radiocarbon dating and stable isotope analyses confirm that the species was established in this region by the Roman period, probably originating from translocated, rather than native, Mediterranean populations. Clarifying the origins of fallow deer in North-western Europe is critical for understanding the dynamics of species exchange around the Roman Empire.
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RBINS Staff Publications 2020
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Benchtop μXRF as a tool for speleothem trace elemental analysis: Validation, limitations and application on an Eemian to early Weichselian (125–97 ka) stalagmite from Belgium
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RBINS Staff Publications 2020
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Reconstructing seasonality through stable-isotope and trace-element analyses of the Proserpine stalagmite, Han-sur-Lesse cave, Belgium: indications for climate-driven changes during the last 400 years
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RBINS Staff Publications 2020
