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- Title
Mineral composition of sediments underlying the Velenje lignite seam in the P-9k/92 borehole (Slovenia).
- Authors
ČERU, Teja; DOLENEC, Matej; MARKIČ, Miloš
- Abstract
The paper presents the results of granulometrical, geochemical and mineralogical characterisation of sediments underlying the Velenje lignite seam as drilled through the P-9k/92 borehole in the central part of the Pliocene intermontane Velenje Basin. This study of differently lithified sediments/sedimentary rocks is based on analyses of 32 samples from 21 core intervals at the depth of 562.6-580.0 m (end of the borehole). Grain size was analysed on 12 samples, 24 samples were investigated geochemically, while mineral composition was obtained with X-ray diffraction (XRD) on 23 samples, and optical microscopy was performed on 7 samples. Granulometry of very low lithified samples revealed that they are mostly clayey silts (>85 % of the silt fraction), only two are silty sands and one is pebbly/rubbly sandstone. Well-lithified clastics are all sandstones cemented by calcite, siderite and/or marcasite. Geochemical analysis indicated that most samples are SiO2 + Al2O3 rich (>60-80 %). Some sediments, mostly at the base of the profile, are enriched in Fe2O3 and inorganic C both indicating the presence of siderite. At the top of the profile, thin limestone and gravelly sandstone beds contain a high c aO content and have high loss on ignition (LOI). Qualitative X r D analysis and microscopy showed that all clastic sediments consist of quartz, kaolinite and muscovite/illite. Feldspars occur sporadically, mainly in sands and sandstones. Gypsum was found in some samples of siltstones. Pyrite occurs only in a sample of limestone at the top of the profile. Also marcasite was found only in one sample.
- Subjects
VELENJE (Slovenia); SEDIMENTS; LIGNITE; BOREHOLES; X-ray diffraction; ANALYTICAL geochemistry
- Publication
Geologija (0016-7789), 2015, Vol 58, Issue 1, p7
- ISSN
0016-7789
- Publication type
Article
- DOI
10.5474/geologija.2015.001