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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Journal ArticleDOI
Evolution of the paleogeodynamic settings of the formation of the Lower and Middle Riphean sedimentary sequences of the Uchur-Maya region and the Bashkir meganticlinorium
TL;DR: In this article, the possibility to use standard discrimination diagrams such as K2O/Na2O-SiO2/Al2O3, SiO2-K2O+MgO)-TiO2, F1-F2, Th-La-Sc, Sc-Th-Zr/10, and Sc/Cr-La/Y for deciphering the paleogeodynamic settings of sedimentary sequences is considered with reference to the Lower and Middle Riphean (Mesoproterozoic) deposits of the Uchur
Journal ArticleDOI
Petrological features of a Numidian section in the Lucanian Apennine (southern Italy)
TL;DR: A continuous section of Numidian sandstones cropping out along the eastern margin of the Lucanian Apennine (southern Italy) has been studied in relation to its petrographic and geochemical aspects as mentioned in this paper.
Journal ArticleDOI
Geology and geochemistry of Kurkur bentonites, southern Egypt: provenance, depositional environment, and compositional implication of Paleocene–Eocene thermal maximum
TL;DR: A large lower Eocene bentonite deposit at the top of the Sinn El-Kaddab plateau, southern Egypt, is investigated in this article, where Clay and silt fractions constitute up to 95% of the bentonite and calcium montmorillonite is the predominant phase.
Journal ArticleDOI
Geochemical and organic petrological study of bituminous sediments from Dahomey Basin, SW Nigeria
J. E. Ogala,Stavros Kalaitzidis,Kimon Christanis,Omoleomo Olutoyin Omo-Irabor,Adewale Akinmosin,Caleb Ugbede Yusuf,Nikos Pasadakis,Miltiadis Constantinopoulos,H. Papaefthymiou +8 more
TL;DR: In this article, the authors examined the turbonian-Maastrichtian Afowo Formation in the Dahomey Basin, SW Nigeria, using sedimentological, mineralogical, petrographical, geochemical, and radiological techniques with the aim of assessing the origin and the thermal maturity of the organic facies.
Journal Article
The Difunta Correa metasedimentary sequence (NW Argentina): relict of a Neoproterozoic platform? — elemental and Sr-Nd isotope evidence
TL;DR: La Sierra de Pie de Palo (Sierras Pampeanas Occidentales, Argentina) is a region of Gondwana in el Cambrico inferior, situada en el antepais Andino, formed by un basamento mesoproterozoico and una cubierta metasedimentaria ediacarense.
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