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Wyszukujesz frazę "Sandstone Petrography" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Provenance of the Malužiná Formation sandstones (Western Carpathians, Slovakia): constraints from standard petrography, cathodoluminescence imaging, and mineral chemistry of feldspars
Autorzy:
Vdacny, M.
Powiązania:
https://bibliotekanauki.pl/articles/2060008.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Sandstone Petrography
Cathodoluminescence
Mineral Chemistry
provenance
Opis:
Petrographic, cathodoluminescence, and phase chemistry studies of detrital grains were carried out on sandstones from the Permian Malužiná Formation in the Malé Karpaty Mts. (Hronic Unit, Western Carpathians, Slovakia) to determine their provenance and tectonic setting during the Permian. The results of the present study suggest derivation of the Malužiná Formation sandstones from multiple source areas. Major source lithologies were acid (felsic) plutonic rocks and low- to high-grade metamorphic rocks (probably metamorphosed igneous rocks and metasedimentary rocks), but notable amounts of detritus were also derived from felsic and mafic volcanic rocks. There was only a minor contribution from sedimentary rocks. Detritus was stripped rapidly from broken, high-relief source areas before weathering processes could destroy unstable framework constituents, as documented by the relatively high content of unstable rock fragments and the high feldspar content in the sandstones investigated. The provenance characteristics indicate that deposition of the sandstones of the Malužiná Formation occurred in a rifted continental margin environment supplied from an uplifted area on a thick continental crust composed of rocks of older fold belts.
Źródło:
Geological Quarterly; 2013, 57, 1; 61--72
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Petrographic and geochemical study of the Maastrichtian Ajali Sandstone, North Central Nigeria
Autorzy:
Ogala, J. E.
Olobaniyi, S. B.
Omo-Irabor, O. O.
Adaikpoh, E. O.
Powiązania:
https://bibliotekanauki.pl/articles/2059843.pdf
Data publikacji:
2015
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
petrography
geochemistry
Ajali Sandstone
provenance
tectonic setting
Opis:
he Upper Cretaceous Ajali Sandstone is an extensive stratigraphic unit of the Anambra Basin in southern Nigeria. It consists of friable, white cross-bedded sandstones exhibiting a fining upward sequence. Structures such as bioturbation, planar and herringbone cross beds indicate variability in depositional environment ranging from fluviatile to deltaic. Petrographic and geochemical compositions (major and trace elements) of these sandstones have been investigated to determine their provenance, tectonic setting and weathering conditions. Fifteen sandstone samples examined are rich in quartz but poor in feldspar and lithic fragments. Texturally, the framework grains of the sandstones are fine- to medium-grained, sub-angular to sub-rounded, moderately sorted to poorly sorted, positively skewed and leptokurtic. The sandstones are texturally immature as depicted by their sub-angular edges of grains, but mineralogically mature in terms of high percentage of quartz. The high chemical index of alteration (CIA) values (71.0–99.2%) for these sandstones suggests that they were derived from highly weathered rocks in the source area. The composition of the major oxides in the sandstones revealed that SiO2 (49.1–99.7%), Al2O3 (0.2–30.3%), Fe2O3 (0.4–1.8%) and TiO2 (0.06–3.2%) were the most abundant elements in all sandstone samples indicating a high detrital quartz and clay mineral content. The Al2O3/TiO2 ratios (1.47 to 12.48), Ti/Zr (6.48–18.63) and Zr/Cr (2.24–22.36) suggest that the sandstones were derived from variable basement complex rocks, including some contribution from mafic or ultramafic components. Inferences from the plots of K2O/Na2O versus SiO2 indicated a passive margin tectonic setting for the sandstones. The high loading of CaO and Na2O in more than 50% of the samples is indicative of terrigenous input, mainly in the form of carbonates and silicates. These results are generally consistent with a derivation of the sandstones from adjacent igneous and metamorphic basement complexes (Cameroon–Adamawa highlands and Oban Massif) while the extensive and blanket-like geometry of the Ajali Sandstone is indicative of an excellent reservoir for groundwater in the Anambra Basin.
Źródło:
Geological Quarterly; 2015, 59, 1; 79--90
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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