Search publications of the members of the Royal Belgian institute of natural Sciences
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The Tachakoucht–Iriri–Tourtit arc complex (Moroccan Anti-Atlas): Neoproterozoic records of polyphased subduction-accretion dynamics during the Pan-African orogeny
- We report new mapping, tectonic, metamorphic and U–Pb zircon dating data on the polyphased Tachakoucht–Iriri and Tourtit arc-related units within the Moroccan Pan-African belt (Sirwa window, Anti-Atlas). The studied area contains four different sub-units, from south to north: (1) the Tachakoucht gneisses intruded to its northern part by (2) Iriri intrusions. To the north, the Tachakoucht–Iriri massif is thrusted by (3) the south-verging 760 Ma Khzama ophiolitic sequence intruded by (4) the Tourtit meta-granitic complex. The Tachakoucht gneiss represents former andesitic to dacitic porphyritic rocks crystallized around 740–720 Ma in an intra-oceanic arc setting (IOAS). Subsequently, it has been buried and metamorphosed to 700 °C, 8 kbar in response to early accretion of the arc onto the West African Craton (WAC). This tectono-metamorphic event also led to the dismembering and stacking of back-arc ophiolite onto the arc unit. Subsequently, the Iriri intrusions, a suite of hydrous mafic dykes (hornblende gabbro and fine-grained basalt) and ultramafic (hornblendite) plutons showing subduction zone affinities, intruded the Tachakoucht gneiss under P–T conditions of 750–800 °C and 2–5 kbar. Emplacement of Iriri intrusions led locally to pronounced partial melting of the Tachakoucht gneiss and to the production of leucogranitic melts. These melts crop out into the Iriri–Tachakoucht gneiss contacts as leucogneissic bands (former leucosomes, dated at 651 ± 5 Ma) but also intruded the Khzama ophiolite to form the Tourtit granite (dated at 651 ± 3 Ma). These ages (651–641 Ma) also constrain the timing of Iriri intrusion emplacement. The entire complex has been overprinted by a second deformation event under greenschist to amphibolite facies conditions marked by transposition of primary structures and a development of mylonitic shear zones. These results and those published on the Bou Azzer window show that two phases of subduction-related magmatism occurred in the Anti-Atlas belt and that they were separated by an early accretion of the intra-oceanic arc system (IOAS) onto the West African craton passive margin. Our interpretations also validate thermo-mechanical models predicting an intense perturbation of subduction dynamics during arc-continent collision (i.e. composite subductions, polarity reversal) which can expand the production of typical hydrous arc magma and induces a late magmatic phase after partial or total accretion of the IOAS.
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The mitochondrial cytochrome <i>c</i> oxidase I gene reveals phylogeographic structure in the African Goshawk <i>Accipiter tachiro</i> (Accipitridae)
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Second Record and DNA Barcode of the Ant Tyrannomyrmex rex Fernández (Hymenoptera: Formicidae: Myrmicinae)
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The Lahonry quarry at Lompret, Belgium: an extraordinary new site to study Upper Frasnian cephalopods during the onset of anoxia in the Dinant Basin
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Upper Frasnian deposits at the Lahonry quarry (Lompret, Belgium): conodont biostratigraphy, microvertebrates and bentonites
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Blood, sweat, tears and … fun! Gladiator and animals fights in Pisidia
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The link between microbial diversity and nitrogen cycling in marine sediments is modulated by macrofaunal bioturbation
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Two new species of <i>Leptanilloides</i> Mann, 1823 (Formicidae: Dorylinae) from the Andes of southern Ecuador
- Two new species of Leptanilloides are described: L. copalinga Delsinne & Donoso sp. nov., and L. prometea Delsinne & Donoso sp. nov., based on workers collected in the leaf litter and soil of the Andes of southern Ecuador. Both species belong to the L. biconstricta species-group (formally diagnosed here). The metatibial gland, considered a synapomorphy for Dorylinae, is observed in L. prometea sp. nov. but seems absent in L. copalinga sp. nov. We provide a COI DNA barcode for both species and a revised key for the worker caste of all known species in the genus. We also describe a single male identified as a potential new Leptanilloides species on the basis of morphology. Furthermore, its mitochondrial COI gene sequence does not match any previously barcoded species. However, we refrain from giving it a specific name because of our lack of knowledge about the worker caste. So far, half of the 14 Leptanilloides species have been discovered above 1500 m in the mountain forests or páramos of the Ecuadorian Andes, confirming, if needed, the biological significance of these threatened habitats.
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Daily temperature fluctuations alter interactions between closely related species of marine nematodes
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Intraspecific functional trait variability does not result in higher fitness under thermal stress in a free-living marine nematode
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Effects of the feral goat population explosion on Alcedo Volcano Isabela, Galapagos between 1986 and 1996.
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Arabel, son histoire.
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Arabel, de geschiedenis
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Evaluation of recent nature development measures in the river IJzer estuary and long-term ground beetle and spider monitoring (Coleoptera, Carabidae: Araneida)
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The impact of spontaneous and induced afforestation on spider diversity in the "Voeren"region
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Two new Neotropical genera of the spider family Zodariidae (Araneae)
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Les araignées du Ru de Targnon (comme de Theux, Province de Liège, Belgique)
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Evaluation of the effects of recent nature development measures in the Yser Estuary on ground beetle and spider assemblages.
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Integrated monitoring of nature restoration along ecotones, the example of the year Estuary
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