Journal ArticleDOI
Geochemical classification of terrigenous sands and shales from core or log data
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TLDR
In this article, a means of relating geochemical concentrations to existing sandstone classification schemes is proposed based on three chemical parameters: the SiO2/Al2O3 ratio, the Fe 2O3/K2O ratio, and the Ca content.Abstract:
A means of relating geochemical concentrations to existing sandstone classification schemes is based on three chemical parameters: the SiO2/Al2O3 ratio, the Fe2O3/K2O ratio, and the Ca content. In terrigenous sands and shales, the SiO2/Al2O3 ratio separates Si-rich quartzarenites from Al-rich shales, with other sand types showing intermediate values. The ratio of total iron (as Fe2O3) to K2O separates lithic sands (litharenites and sublitharenites) from feldspathic sands (arkoses and subarkoses). In addition, very high Fe2O3/K2O ratios indicate Fe-rich shales (e.g., pyritic, sideritic, hematitic) or Fe-rich sands (e.g., gl uconitic) depending on the silica/alumina ratio. The Ca content is used to differentiate noncalcareous from calcareous sandstones and shales and to separate siliciclastic from carbonate rocks. Sandstones are classified the same by this scheme as by petrographic analysis about 84% of the time, and shales are effectively discriminated from sandstones. The requisite input data can be accurately supplied by geochemical well-logging measurements, enabling unbiased sandstone classification to be displayed on a continuous basis with depth.read more
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Journal ArticleDOI
Origin of Neoproterozoic metamorphic suites along the Western Segment of Allaqi Shear Zone, Southern Egyptian Nubian Shield
Abdelhamid El Fakharani,Abdelhamid El Fakharani,Abdelhady Radwan,Mohammed Hassan Younis,Ashraf Emam,Sherif Fawzy +5 more
TL;DR: In this paper, the Neoproterozoic basement complex of the western segment of the Allaqi Shear Zone (ASZ) in the extreme southern part of the Egyptian Nubian Shield comprises four main lithologic units: gneisses, amphibolites, island arc metasediments, and intrusives.
Journal ArticleDOI
Age and Depositional Settings of the Ordovician Chalovskaya Group in the Argun Massif, Eastern Part of the Central Asian Fold Belt
Yu. N. Smirnova,A. A. Sorokin +1 more
TL;DR: The results of mineralogical and geochemical studies of the metaclastic rocks of the Grebnev and Magdagachi sequences of the Chalovskaya Group, one of the key lithostratigraphic units of the Argun continental massif in the eastern part of the Central Asian Fold Belt, as well as the results of the U-Pb dating of detrital zircons from these rocks by the LA-ICP-MS method, are presented as discussed by the authors.
Journal ArticleDOI
Mineralogy and geochemistry of oil shale in Azerbaijan: classification, palaeoweathering and maturity features
TL;DR: In this article, the authors investigated the chemical classifications, provenience, palaeoweathering and maturity characteristics of oil shale in Shamakhi-Gobustan and Absheron regions (Azerbaijan).
Journal ArticleDOI
Whole-rock geochemistry and Sr-Nd isotopic composition of the pre-rift sequence of the Camamu Basin, northeastern Brazil
Diogo Rodrigues Andrade da Silva,Ana Maria Pimentel Mizusaki,Edison J. Milani,Márcio Martins Pimentel,Koji Kawashita +4 more
TL;DR: In this article, the major and trace element contents as well as Sr-Nd isotopic compositions of whole-rock shale samples from five outcrops attributed to the pre-rift supersequence of the Camamu Basin were analyzed with the purpose of characterizing and obtaining further information that would allow a better correlation between the sites studied.
Journal ArticleDOI
Late Vendian unfolded Molasse in the northeastern, eastern, and southwestern peripheries of the east European platform: Distinctive lithogeochemical features
A. V. Maslov,V. P. Podkovyrov +1 more
TL;DR: In this article, the authors report data on the lithogeochemistry of sandstones and silty mudstones from Upper Vendian sedimentary sequences in the northeastern, eastern, and southwestern peripheries of the East European Platform belonging to the so-called unfolded molasse.
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