Geologica Belgica 

About: Geologica Belgica is an academic journal published by University of Liège. The journal publishes majorly in the area(s): Devonian & Carboniferous. It has an ISSN identifier of 1374-8505. Over the lifetime, 509 publications have been published receiving 5822 citations.

Distribution and contamination status of heavy metals in estuarine sediments near cua ong harbor, ha long bay, vietnam

Abstract: The distribution, controlling geochemical factors and contamination status of heavy metals in estuarine sediments near Cua Ong Habor, Ha Long Bay (Vietnam) were investigated. 36 surface sediment samples were collected and analyzed for major elements (Al, Ca, Fe, K, Mg, S), heavy metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn), organic matter, loss on ignition (LOI), grain size composition and pH. Spatial distribution patterns of heavy metals as well as their controlling factors were elucidated based on geochemical mapping and statistical methods such as the Pearson Product- Moment linear correlation and Factor Analysis. The results illustrated that the distribution patterns of As, Cd, Cr, Cu, Ni, Pb and Zn are mainly controlled by organic matter and clay minerals and determined by the distribution of the fine- grained fraction (Φ < 63 µm) in the sediments. In contrast, Fe and Mn compounds seem to exert some control on the distribution of Co. Carbonates partly control the distribution of Mn, but are not important with respect to the other studied heavy metals. The contamination status by heavy metals was assessed based on comparison with Canadian, Wisconsin- United States and Flemish numerical Sediment Quality Guidelines, and calculation of Geo-accumulation Index (Igeo) and Enrichment Factor (EF). The results indicated that natural processes such as weathering and erosion of bedrock are the main supply sources of heavy metals in sediments near Cua Ong Harbor. Among the studied heavy metals, only As is of concern whereas Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn seem to reflect their background concentrations in sediments of Ha Long Bay.

Devonian lithostratigraphic units (Belgium)

Abstract: This contribution briefly describes seventy Devonian formations from the Dinant and Namur Synclinoria, the Vesdre Nappe and the Theux Window, that were revised or introduced during the previous two decades. The descriptions of the formations are organized in four parts, Lower Devonian, Middle Devonian, Frasnian and Famennian, corresponding to major and minor transgressive and regressive events and demonstrating each typical lithological characteristics. In each part, the following presentation has been adopted: the formations occurring in the Southern part of the Dinant Synclinorium are first described from base upwards, followed by a description of the formations restricted to the central and/or northern part of the Dinant Synclinorium, the Namur Synclinorium, the Vesdre Nappe and the Theux Window.

Paleogene and Neogene lithostratigraphic units (Belgium)

Abstract: The presented lithostratigraphy of the Paleogene and Neogene deals only with the formal lithostratigraphic units of formation rank or higher (groups). The names of the lower rank units (members and beds) are just mentioned without description or other information. This lithostratigraphy corresponds largely with the legend of the new series of geological maps of Belgium - Flanders Region on scale 1:50.000, edited since 1993.

Cambrian-Ordovician-Silurian lithostratigraphic units (Belgium)

Abstract: The National Subcommission on the Stratigraphy of the Lower Palaeozoic of Belgium has evaluated the previous and present definitions of the Cambrian, Ordovician and Silurian lithostratigraphical units (groups, formations and members) and presents in this paper the results of this evaluation. Some of these units described in published or unpublished documents are considered to be junior synonyms of previously described units. Other units were given a higher or lower ranking. Units that are too thin or too thick were abandoned. The Subcommission reached agreement on the validity and usefulness of all the units that are described below. For each of them, a lithological and sedimentological description is given, the area of distribution and possible facies changes, the thickness of the unit, the arguments for the age determination, some remarks about the history of the definitions, and the names of units considered to be junior synonyms. In the Brabant Massif 32 formations are (re) defined and described, in the Condroz inlier 18 formations, in the Stavelot Massif 3 groups, 8 formations and 8 members, with an additional formation with an unspecified Mid Ordovician-earliest Devonian age, in the Rocroi Massif 3 groups, 7 formations and 2 members, in the Givonne Inlier 4 formations and in the Serpont Inlier 2 formations. The formations are shown in chronostratigraphical tables with a colour encoding the dominant lithology or sedimentology.

Rietveld refinement strategy for quantitative phase analysis of partially amorphous zeolitized tuffaceous rocks

Abstract: The Rietveld method has become one of the most popular methods in quantitative mineralogical analysis based on X-ray powder diffraction. An estimate of the amorphous phase content can be made by introducing a known amount of an appropriate internal standard. This method was applied to a selected set of zeolitized tuffaceous rocks to develop guidelines for Rietveld quantitative phase analysis in complex mixtures. A local sensitivity analysis of selected refinable parameters was performed and phase abundance results for synchrotron and laboratory based X-ray diffraction data collection were compared. The calculated amorphous phase fraction showed a very high sensitivity towards the refined amount of internal standard, in particular when small amounts of amorphous phase were encountered in the samples. Optimal reproducibility of phase abundance results was obtained when a sufficient number of background polynomials was employed and the internal standard thermal parameters were not refined. A very good correlation between laboratory and synchrotron data was achieved when the communicated refinement strategy was followed, supporting the use of laboratory equipment for routine quantitative mineralogical analysis.