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
Citations
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Journal ArticleDOI
Early Paleozoic arc-accretion in the northern branch of the Proto-Tethys Ocean : New insights from detrital zircon U-Pb ages and geochemistry of paraschists from the Kuanping Complex, North Qinling Orogenic Belt, China
TL;DR: In this paper, the authors present a systematic study of the petrology, whole-rock geochemistry and geochronology of paraschists from the Kuanping-Kuanping complex.
Journal ArticleDOI
First palynostratigraphical evidence for a Late Eocene to Early Miocene age of the volcano-sedimentary series of Dschang, western part of Cameroon and its implications for the interpretation of palaeoenvironment
Bessong Moise,Hell Joseph Victor,Susanne Feist Burkhardt,Elias Samankassou,Mouloud Bennami,Nolla Junior Désiré,Mbesse Cecile Olive,Thierry Adatte,Rossana Martini,Michel Brunet,Michel Brunet +10 more
TL;DR: In this article, the authors provided the first biostratigraphical data of the volcano-sedimentary sequence and allowed constraining the age and the position of this basin within the regional context of Central Africa.
Journal ArticleDOI
Tectonically‐controlled Evolution of the Late Cenozoic Nihewan Basin, North China Craton: Constraints from Stratigraphy, Mineralogy, and Geochemistry
TL;DR: In this article, Chengqiang and Hongyanangou stratigraphic sections of the Nihewan Basin are divided into three evolutionary stages, such as alluvial fan-eolian red clay, fan delta, and fluvial, with boundaries at ~2.8 and ~1.8 Ma.
Journal ArticleDOI
Regional sediment sources versus the Indus River system: The Plio-Pleistocene of the Peshawar Basin (NW-Pakistan)
TL;DR: In this paper, the Peshawar Basin has been studied during the Plio-Pleistocene epoch and it is shown that detritus derivation from dominantly acidic igneous sources with contribution from medium-grade metamorphic rocks.
Journal ArticleDOI
Constraints on the age and geodynamic setting of the iron formations and anhydrite Fe-(Ba) deposits in the Bulunkuole Group of the Taxkorgan area, NW China
TL;DR: In this paper, the Bulunkuole Group (BG) is classified into three subgroups: the lowermost subgroup 1 is a bimodal volcanic suit (basalts and dacites) interbedded with IF layers; the overlying Subgroup 2 is a clastic sedimentary sequence hosting abundant anhydrite Fe-(Ba) mineralization; and the uppermost Subgroup 3 is dominated by carbonate rocks.
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