Journal ArticleDOI
Geochemical classification of terrigenous sands and shales from core or log data
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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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Petrological, whole–rock geochemical, geochronological, and Lu–Hf isotope constraints on the regional tectonic evolution of the Laoling Group in northeastern Jiao–Liao–Ji Belt, North China Craton
TL;DR: This article examined the original nature, tectonic setting, and evolution of Paleoproterozoic metasedimentary rocks in the Laoling Group of northern Jiao-Liao-Ji Belt (JLJB), in the northeastern margin of the Eastern Block of the North China Craton (NCC), using new petrological, whole-rock geochemical, geochronological, and Lu-Hf isotope data.
Journal ArticleDOI
Detrital zircon age constraints for Late Permian to Late Triassic clastic sedimentation in the northern-western Sakar-Strandzha Zone, SE Bulgaria
TL;DR: In this article, the authors presented new geochemical data and U-Pb detrital zircon geochronology for ten samples from these clastic units, which revealed the presence of arkoses-subarkoses, which have similar trace element and REE characteristics when compared to the Late Carboniferous-Permian and Middle Triassic magmatic bodies in the SASTZ.
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Geology and Geochemistry of Sediments from Lewumeji and Idogun Wells, Eastern Dahomey Basin Southwestern Nigeria
O. C. Adeigbe,C. B. Oyekola +1 more
TL;DR: In this paper, the core samples from Lewumeji and Idogun (0-111m) and the Abeokuta Group, Eastern Dahomey Basin, were subjected to detailed lithologic and geochemical studies.
Journal ArticleDOI
Sedimentary geochemistry of Late Cretaceous-Paleocene deposits at the southwestern margin of the Anambra Basin (Nigeria): Implications for paleoenvironmental reconstructions
TL;DR: In this article , a detailed geochemical analysis was performed using major elements, trace elements and rare earth element data, as well as the mineralogical characterization of 20 samples from two wells.
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