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
Citations
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Journal ArticleDOI
Cryptic climatic signatures and tectonic controls on Cryogenian diamictites in the NW Tarim Craton, China
TL;DR: In this paper, the authors present new sedimentological and geochemical data for the Cryogenian sedimentary rocks from the Tarim Craton, NW China, and suggest that both the Qiaoenbrak Group and Yuermeinak Formation were deposited during the Marinoan glaciation, in a longlasting cold and dry interval.
Book ChapterDOI
Chemostratigraphy and Chemofacies of Source Rock Analogues: A High-Resolution Analysis of Black Shale Successions from the Lower Silurian Formigoso Formation (Cantabrian Mountains, NW Spain)
T. Ferriday,Michael Montenari +1 more
TL;DR: In this paper, high-resolution whole rock geochemical data obtained from an early Silurian black shale source rock analogue (Formigoso Formation, Cantabrian Mountains, NW, Spain) are used to develop a chemostratigraphic framework and to reconstruct and further constrain the paleoenvironmental conditions that prevailed at the time of deposition.
Journal ArticleDOI
Provenance of the Walash-Naopurdan back-arc–arc clastic sequences in the Iraqi Zagros Suture Zone
TL;DR: In this article, the authors classified the Eocene Walash and Oligocene Naopurdan clastic rocks and showed that they were mainly derived from associated sub-alkaline basalt and andesitic basalt in back-arc and island arc tectonic settings.
Journal ArticleDOI
Provenance analysis and tectonic setting of the Upper Jurassic Series in Mohe Basin, northeast China: Implication for the closure of Mongol–Okhotsk Ocean
Qian Zhang,Chenyue Liang,Chenyue Liang,Yongjiang Liu,Changqing Zheng,Changqing Zheng,Weimin Li,Weimin Li +7 more
Journal ArticleDOI
Geochemical and textural investigations of the Eoarchean Ukaliq supracrustals, Northern Québec (Canada)
Wriju Chowdhury,Dustin Trail,Martin Guitreau,Elizabeth A. Bell,Jacob Buettner,Stephen J. Mojzsis,Stephen J. Mojzsis +6 more
TL;DR: In this article, textural and geochemical studies for a suite of rocks from the Ukaliq Supracrustal Belt (USB), located approximately 3 km northeast of the NSB, were performed.
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