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
Geochemistry of Miocene sedimentary rocks from offshore West Baram Delta, Sarawak Basin, Malaysia, South China Sea: implications for weathering, provenance, tectonic setting, paleoclimate and paleoenvironment of deposition
TL;DR: In this paper, the authors examined the deposition of offshore Miocene sedimentary rocks in the West Baram Delta through multi-element geochemistry and mineralogy using XRF, thin sections and FESEM.
A Bodai Aleurolit Formáció törmelékes kőzettípusainak ásványtani, kőzettani és geokémiai jellemzői | Mineralogical, petrological and geochemical characteristics of thesiliciclastic rock types of Boda Siltstone Formation
Abstract: Munkankban a felső-permi Bodai Aleurolit Formacio (BAF, Del-Dunantul, Mecsek) sziliciklasztos
kőzettipusainak (agyagkő, aleurolit, homokkő es albitolit) asvanytani, kőzettani es geokemiai jellemzeset
vegeztuk el. Az agyagkovekben az illit±muszkovit, a hematit es a klorit mennyisege altalaban nagyobb,
mint az albitolitokban, az aleurolitokban es a homokkovekben. Ezzel ellentetben a BAF durvabb
szemcsemeretű kőzettipusainak albit-, kvarc- es karbonattartalma jelentősen meghaladja az
agyagkovekre jellemző ertekeket. A nagyobb elsődleges porozitasnak megfelelően a homokkovekben es
az aleurolitokban a tormelekes foldpatok diagenetikus albitosodasa es a karbonatcementacio merteke nagyobb, mint az agyagkovekben. A vizsgalt kőzettipusok kemiai osszetetele szinten a diagenetikus
albitosodashoz kapcsolodo folyamatok hatasat tukrozi. Az aleurolitok es a homokkovek SiO(2)-, Na(2)O-,
CaO-, MnO-, Sr- es Ba-tartalma viszonylag nagy. Masreszt az Al(2)O(3), a Fe(2)O(3), a MgO, a K(2)O es a Rb
mennyisege az agyagkovekben jelentős, amely a retegszilikatok es a hematit nagyobb aranyat tukrozi.
A BAF homokkoveinek tormelekanyagaban a jelentos mennyisegu savanyu vulkani kőzetanyag a
permi Gyűrűfűi Riolit Formacio lepusztulasabol szarmazik. A metamorf eredetű tormelekanyagot a
kristalyos aljzat lepusztulasa szolgaltatta. A felzikus atlagos osszetetelű lehordasi teruletet erősiti meg az
agyag- es homokkovek ritkafoldfem (RFF)-eloszlasa is, amely a felső kontinentalis kereg eredetű
tormelekes kőzetek RFF-eloszlasanak felel meg. A neutralis–bazisos jellegű tormelekszemcsek a BAF
lehordasi teruleten – alarendelt mennyisegben – mafikus osszetetelű kőzetek jelenletere utalnak. | In this paper, results of mineralogical, petrological and geochemical studies of siliciclastic sedimentary
rock types (claystone, siltstone, sandstone and albitolite) of the Upper Permian Boda Siltstone Formation
(BSF) from southern Transdanubia (Mecsek Mountains, SW Hungary) are presented. The claystone
samples generally have higher illite±muscovite, hematite and chlorite contents relative to the albitolite,
siltstone and sandstone samples. In contrast, the BSF rock types with coarser grain-size have higher
albite, quarz and carbonate contents relative to the claystone samples. Degree of the diagenetic
albitisation of the detrital feldspars and carbonate cementation rate are higher in the siltstone and
sandstone samples, corresponding to their higher primary porosity, than those in the claystone samples.
Additionally, geochemistry of the studied BSF lithotypes also reflects the effect of the diagenetic
processes during albitisation. The siltstone and sandstone samples have relatively high SiO(2), Na(2)O, CaO,
MnO, Sr and Ba contents. On the other hand, the claystone samples have high Al(2)O(3), Fe(2)O(3), MgO, K(2)O
and Rb contents reflecting their higher phyllosilicate and hematite contents.
In the sandstone samples of the BSF, the presence of abundant felsic volcanic rock fragments suggests
a provenance from the Permian Gyűrűfű Rhyolite Formation. Metamorphic source components might
have been derived from the uplifted basement rocks. A relatively felsic provenance area is also
supported by the rare earth element (REE) contents of the claystone and sandstone samples showing
REE patterns typical of continentally-derived sediments. The presence of intermediate–basic volcanic
rock fragments suggests a mafic source component of the provenance area of the BSF in inconsiderable
amounts.
OtherDOI
The Pan-African nappe tectonics in the Shackleton Range
TL;DR: Buggisch et al. as discussed by the authors presented a review of the nappe tectonics of the Shackleton Range, its history and its plate tectonic consequences, including the Pan-African nappes with south-directed transport in the southern Shackleton range and west transport with north-directed transportation in the north.
Journal ArticleDOI
Geochemical characteristics of Late Triassic sandstones in the western part of Bayan Har Basin, Northern Tibetan Plateau, Western China: Constraints on provenance, source weathering, tectonic setting, and palaeoenvironment
Xinwang Lin,Zhenkai Zhang,Xiangdong Liu,Ning Chen,Tong Wu,Yafeng Zhang,Pengbin Zhao,Xinqi Ma,Zhenzhu Zhou +8 more
Journal ArticleDOI
Tectonostratigraphy and depositional history of the Neoproterozoic volcano-sedimentary sequences in Kid area, southeastern Sinai, Egypt: Implications for intra-arc to foreland basin in the northern Arabian–Nubian Shield
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