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V Debacker L S Schiettecatte T Jauniaux J M Bouquegneau 《Marine environmental research》2001,52(5):427-444
The common guillemots, Uria aalge, found stranded at the Belgian coast, display high levels of Cu in both liver and kidneys. The condition index of the animals, defined as the ratio of liver to kidneys mass (Wenzel & Adelung, 1996, The suitability of oiled Guillemots (Uria aalge) as monitoring organisms for geographical comparisons of trace element contaminants. Archives of Environmental Contamination and Toxicology, 31, 368-377), influences both the metal concentration and its binding to metallothioneins (MT): the lower the condition index, the more emaciated the animals, and the higher the total Cu concentration and the concentration of Cu bound to MT. In less robust individuals, our results suggest that Cu could displace Zn from MT, rendering the Zn ions available to induce a new MT synthesis. Sex-related effects also emerged as significantly higher hepatic MT as well as Cu- and Zn-MT concentrations were found in emaciated male guillemots compared to females. In both organs, Cd concentrations remained low and typically demonstrated an age-dependent renal accumulation, with no noticeable effect of the condition index. As a whole, these results suggest that, for guillemots found stranded at the Belgian coast. Cu binding to hepatic and renal MT could function as a protective mechanism, rendering the metal ions unavailable to exert any cytotoxic activity. 相似文献
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The presence of convergent cleavage fans in folded Silurian pelitic deposits along the southern extremity of the Brabant Massif has commonly been considered as an indication for a polyphase deformation history. Recent field work on the classic section at Ronquières shows, however, that all the structural elements can be explained by a single progressive deformation, taking place at gradually higher structural levels. This deformation is considered to have occurred at the time of the Acadian orogeny. The section under study contains a fold train of five gentle to open first-order folds, unconformably overlain by gently S-dipping Givetian rocks. Although the Silurian turbidite deposits are predominantly pelitic, the folds are characterized by convergent cleavage fans. The trend of the cleavage fan axes remains constant in the various folds throughout the section. In contrast, the trend of the folds hinge lines gradually changes along the section from a clockwise relation with the cleavage fan axis in the northern part (anticlockwise cleavage transection) towards an anticlockwise relation in the southern part (clockwise cleavage transection). Individual fault/fault intersections have a constant trend throughout the section, parallel to the cleavage fan axes and the mean fold hinge line. Small kink bands and small transverse joints reflect the same structural trend. The coaxial disposition of the structural elements seems at first sight incompatible with the presence of both clockwise and anticlockwise cleavage-transected folds. This disposition may, however, be explained by an en-echelon periclinal nature of the fold train, possibly formed in a slightly constrictional deformation environment. 相似文献
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K. Piessens Muchez S. Dewaele A. Boyce W. De Vos M. Sintubin T. N. Debacker E. A. J. Burke W. Viaene 《Tectonophysics》2002,348(1-3)
In the Lower Palaeozoic rocks of the Brabant Massif (Belgium), a recently discovered polysulphide mineralisation is related to a low-angle reverse shear zone. This shear zone has been attributed to the main early Devonian deformation event. Data from boreholes and outcrops allow a detailed investigation of the alteration pattern and palaeofluid flow along this shear zone. Macroscopic observations of the mineralogy and quantitative changes in the phyllosilicate mineralogy indicate that this shear zone is characterised by an envelope of intense sericitisation and silicification. In addition, chloritisation is associated with this alteration. The alteration zone may reach a thickness of 250 m. Ore mineralisation occurred synkinematically and is spatially related to the shear zone. The mineralisation consists of pyrite, marcasite, arsenopyrite, pyrrhotite, chalcopyrite, sphalerite, galena, stibnite and smaller amounts of tetrahedrite and other sulphosalts. It is concentrated in quartz–sulphide veins or occurs diffusely in the host rock. The mineralising fluids have a low-salinity H2O–CO2–CH4–NaCl–(KCl) composition and a minimum temperature of 250–320 °C. The δ18O values of quartz vary between +12.3‰ and +14.5‰ SMOW, and δD compositions of the fluid inclusions in the quartz crystals range from −65‰ to −35‰ V-SMOW. The δD and the calculated δ18O values of the mineralising fluids fall in the range typical for metamorphic fluids and partly overlap with that for primary magmatic fluids. The δ34S values, between +4.7‰ and +10.6‰ CDT, fall outside the interval typical for I-type magmas. Important migration of likely metamorphic fluids, causing a widespread alteration and a polysulphide mineralisation along a low-angle shear zone, has, thus, been identified for the first time in the Caledonian Anglo-Brabant fold belt. 相似文献
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Manuel Sintubin Timothy Nick Debacker Hervé Van Baelen 《Comptes Rendus Geoscience》2009,341(2-3):156-173
The Lower Palaeozoic rocks exposed in the Brabant-Ardenne region (Belgium, France) recorded the Early Palaeozoic history on the southern margin of the perigondwanan microcontinent of Avalonia, north of the Rheic suture. These rocks crop out in the Brabant basement and in the Ardenne basement inliers within the Variscan Ardenne allochthon. The two main unconformities are classically associated with distinct orogenic episodes, the Late Ordovician “Ardennian” event and the Early Devonian “Brabantian” event. A review of the current state-of-knowledge with respect to the reconstruction of Early Palaeozoic geodynamics in the Brabant-Ardenne region is presented. It is demonstrated that an unconformity does not necessarily represent an orogenic event, and that the hiatus related to an unconformity does not necessarily coincide with tectonic activity, especially when tectonism is diachronous in nature. The former applies to the Ardennian unconformity, while the latter applies to the Brabantian unconformity. Finally, the well-constrained Brabantian orogeny, as well as the Ardenne-Eifel basin development, is tentatively framed within the Early Palaeozoic geodynamic context of the northern margin of the Rheic realm. By doing so, it is shown that the Brabant-Ardenne region links, both in space and time, the Rheic and Rhenohercynian ocean. 相似文献
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