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
Geochemistry of Devonian–Carboniferous clastic sediments of the Tsetserleg terrane, Hangay Basin, Central Mongolia: Provenance, source weathering, and tectonic setting
Narantuya Purevjav,Barry Roser +1 more
TL;DR: A suite of 94 Tsetserleg sandstones and mudrocks was collected with the aim of constraining provenance, source weathering, and depositional setting, using established petrographic and whole-rock geochemical parameters as discussed by the authors.
Journal ArticleDOI
Provenance and Source Area Weathering Derived from the Geochemistry of Pre-Cenomanian Sandstones, East Sinai, Egypt
Journal ArticleDOI
Separating regional metamorphic and metasomatic assemblages and events in the northern Khetri complex, NW India: Evidence from mineralogy, whole-rock geochemistry and U-Pb monazite chronology
Parampreet Kaur,Parampreet Kaur,Armin Zeh,Armin Zeh,Martin Okrusch,Naveen Chaudhri,Axel Gerdes,Helene Brätz +7 more
TL;DR: The distinction between regional metamorphic and metasomatic mineral assemblages may be occasionally challenging when the two phenomena show a very close spatial and temporal association as mentioned in this paper, and the distinction between local metamorphism and global metasomatism may also be difficult when two phenomena are associated.
Journal ArticleDOI
Provenance and tectonic setting of the supra-crustal succession of the Qinling Complex: Implications for the tectonic affinity of the North Qinling Belt, Central China
TL;DR: The Qinling Complex as mentioned in this paper comprises a basement complex composed of amphibolite and ecologite, overlain by a supra-crustal succession that has been metamorphosed to the upper greenschist facies at approximately 516-509 Ma.
Journal ArticleDOI
From Cadomian magmatic arc to Rheic ocean closure: The geochronological-geochemical record of nappe protoliths of the Münchberg Massif, NE Bavaria (Germany)
Nikola Koglin,Armin Zeh,Gerhard Franz,Ulrich Schüssler,Johannes Glodny,Axel Gerdes,Helene Brätz +6 more
TL;DR: The Munchberg Massif as discussed by the authors is an allochthonous metamorphic nappe complex within the Saxothuringian Zone of the Variscan orogen.
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