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Article Reference Unexpected fish diversity gradients in the Amazon basin
Using the most comprehensive fish occurrence database, we evaluated the importance of ecological and historical drivers in diversity patterns of subdrainage basins across the Amazon system. Linear models reveal the influence of climatic conditions, habitat size and sub-basin isolation on species diversity. Unexpectedly, the species richness model also highlighted a negative upriver-downriver gradient, contrary to predictions of increasing richness at more downriver locations along fluvial gradients. This reverse gradient may be linked to the history of the Amazon drainage network, which, after isolation as western and eastern basins throughout the Miocene, only began flowing eastward 1–9 million years (Ma) ago. Our results suggest that the main center of fish diversity was located westward, with fish dispersal progressing eastward after the basins were united and the Amazon River assumed its modern course toward the Atlantic. This dispersal process seems not yet achieved, suggesting a recent formation of the current Amazon system.
Located in Library / RBINS Staff Publications 2019
Article Reference Unfolding veined fold limbs to deduce a basin’s prefolding stress state
Tectonic structures that developed prior to folding, such as pre- and early-kinematic veins, hold valuable information on the stress state of the paleobasin in which these early structures formed. To derive the parental orientation of these prefolding brittle structures, folds need to be ‘unfold’. A fold restoration methodology is presented in which fold limbs, and structures they contain, are rotated back to their depositional horizontal position by removing the tilt of the fold hinge line and the dip of individual fold limbs. The method is applied on quartz veins emplaced in folded Lower Devonian sandstones from the High-Ardenne slate belt (Belgium, Germany) and allowed deducing NW-SE opening when the Ardenne-Eifel Basin was at maximum burial depth (early Carboniferous). This exercise can be used in structural geology classes to teach how to rotate data using stereonet techniques hereby encouraging students in applying an unfolding strategy to derive information from prefolding structures.
Located in Library / RBINS Staff Publications 2018
Article Reference Unraveling geological and geographical provenances of querns and mills during Roman times at the northern frontier of the Roman Empire (Belgium, Northern France, Southern Netherlands, Western germany): a multidisciplinary research project.
Located in Library / RBINS Staff Publications 2016
Article Reference Unraveling the goblin spiders puzzle: rDNA phylogeny of the family Oonopidae (Araneae)
Located in Library / RBINS Staff Publications
Article Reference Unraveling the PETM in shallow marine Tethyan environments: the Tunisian stratigraphic record.
Despite the increasing understanding of the Paleocene-Eocene thermal maximum (PETM) in open marine environments, shallow marine settings remain relatively unexplored. We investigated an upper Paleocene to lower Eocene shallow-water sequence near Kalaat Senan in Tunisia (Sidi Nasseur and Wadi Mezaz sections)in order to generate a stratigraphic framework of the PETM in shallow marine fine-grained siliciclastic setting on the Southern Tethys. These sections expose the top part of the El Haria Formation (Fm.), the Chouabine Fm. and the lower part of the limestone bearing El Garia Fm., covering the upper Paleocene - lower Eocene (NP9a to NP11). The PETM interval is situated near the top of the El Haria Fm. and the regional stratigraphy is compared to the well-known Egyptian setting. The isotope record of total organic carbon (δ13Corg)reveals the characteristic negative carbon isotope excursion(CIE), comparable to the δ13Corg record of the Global Boundary Stratotype Section and Point of the Eocene at Dababiya (Egypt). Although the Tunesian PETM interval is quite expanded, no anomalous beds are observed and only the "CIE" core is partly represented as the top part of the PETM is truncated. In addition to a well-expressed CIE, the position of the Paleocene-Eocene boundary is supported by the appearance of nannoplankton (Discoaster araneus)and foraminiferal (e.g. Acarinina multicamerata)marker taxa. Furthermore, ostracode and benthic foraminiferal turnovers coincide with the onset of the PETM and are characterized by the disappearance of many common Paleocene taxa (e.g. Frondicularia aff. phosphatica) in this area. The lowest occurrences of Alocopocythere attitogonensis and Buntonia ? tunisiensis (ostracodes), Reophax sp. 1 (benthic foraminifera) and Fasciculithus tonii (calcareous nannplankton) may be applicable for regional correlation. These results indicate that characteristic PETM taxa evolved and/or dispersed immediately after the main δ13Corg shift.
Located in Library / RBINS Staff Publications
Article Reference Unravelling the evolution of Africa’s drainage basins through a widespread freshwater fish, the African sharptooth catfish Clarias gariepinus
Located in Library / RBINS Staff Publications 2020
Article Reference Unravelling the high-altitude Nansen blue ice field meteorite trap (East Antarctica) and implications for regional palaeo-conditions
Antarctic blue ice zones, the most productive locations for meteorite recovery on Earth, contain old ice that is easily accessible and available in large quantities. However, the mechanisms behind these meteorite traps remain a topic of ongoing debate. Here, we propose an interdisciplinary approach to improve our understanding of a meteorite trap in Dronning Maud Land (East Antarctica) on the Nansen blue ice field meteorite trap (2600–3100 m above sea level), where more than half of the Asuka meteorites have been collected. Based on 185 surface blue ice samples, one of the largest observed spatial patterns in oxygen isotopic variation to date is found. Relying on meteorites for which the terrestrial ages are determined using 14C and 36Cl, this surface ice is interpreted to date from the Last Interglacial up to the present-day. By combining state-of-the-art satellite derived surface velocities, surface mass balance modelling and ice flow modelling, we estimate that about 75–85% of the meteorites found on the ice field were supplied by ice flow after entering the ice sheet in an accumulation area of a few hundred square kilometres located south (upstream) of the ice field. Less than 0.4 new meteorites per year are supplied to the ice field through ice flow, suggesting that the hundreds of meteorites found 25 years after the first visit to this ice field mostly represent meteorites that were previously not found, rather than newly supplied meteorites. By combining these findings, the infall rate of meteorites from space is estimated, which is in line with values from the literature, but situated at the higher end of the range. A comparison of the oxygen isotopic variation of the surface blue ice to that of the European Project for Ice Coring in Antarctica (EPICA), Dronning Maud Land (EDML) ice core (located 750 km to the west, at the same elevation), suggests that the regional changes in topography have been relatively limited since the Last Interglacial, supporting theories of an overall stable East Antarctic Ice Sheet (EAIS) over this time period.
Located in Library / RBINS Staff Publications 2019
Article Reference Unravelling the processes controlling apatite formation in the Phalaborwa Complex (South Africa) based on combined cathodoluminescence, LA-ICPMS and in-situ O and Sr isotope analyses.
Located in Library / RBINS Staff Publications 2020
Article Reference Untangling a mess of worms: Species delimitations reveal morphological crypsis and variability in Southeast Asian semi-aquatic earthworms (Almidae, Glyphidrilus)
Located in Library / RBINS Staff Publications 2019
Article Reference Untangling the waterfall damsels: a review of the Mesoamerican genus Paraphlebia Selys in Hagen, 1861 (Odonata: Thaumatoneuridae) with descriptions of 11 new species.
A review of the Mesoamerican genus Paraphlebia Selys in Hagen, 1861 is presented, including diagnoses, illustrations of diagnostic characters, and distribution maps for all species. A key to the known males and females is provided. Eleven new species are described: P. akan Ortega-Salas & González-Soriano. sp. nov., P. chaak Ortega-Salas & González-Soriano sp. nov., P. chiarae Ortega-Salas sp. nov., P. esperanza Ortega-Salas & González-Soriano sp. nov., P. flinti Ortega-Salas & González-Soriano sp. nov., P. hunnal Ortega-Salas & González-Soriano sp. nov., P. itzamna Ortega-Salas, Jocque & González-Soriano sp. nov., P. ixchel Ortega-Salas & González-Soriano sp. nov., P. kauil Ortega-Salas & González-Soriano sp. nov., P. kinich Ortega-Salas & González-Soriano sp. nov., and P. kukulkan Jocque & Ortega-Salas sp. nov.
Located in Library / RBINS Staff Publications 2022