Chemical composition and fractionation of the continental crust

Wedepohl, K. H.

doi:10.1007/bf01829361

Cited by 161 publications

(70 citation statements)

References 46 publications

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“…Low Th/U ratios are rather common in mantle-derived volcanic rocks and reflect the geochemically depleted nature of such reservoirs [58]. Workers like Wedephol (1991) [59] have also shown that the whole rock Th/U ratio is a sensitive indicator of metamorphism in all types of rocks. The Th/U ratios may reach 8-10 in upper amphibolites facies and as high as 25 in the granulite facies.…”

Section: Th/u Ratiomentioning

confidence: 99%

Geochemistry of Palaeoproterozoic Rocks of Aravalli Supergroup: Implications for Weathering History and Depositional Sequence

Singh¹,

Khan²

2017

IJG

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The Paleoproterozoic Aravalli Supregroup of rocks, hosted in Aravalli Craton of NW shield, is deposited in shallow and deep water conditions. The major lithologies are phyllites and quartzites with significant components of greywacks and dolomite. Geochemical indices in particular, CIA (Chemical Index of Alteration) values (avg. phyllites: 51.6 -81.5, avg. quartzites: 57.4 -95.5) calculated from the data of clastic rocks of ASG suggest minimum to highly intense weathering in the source region. Other indices including PIA, CIW and ICV along with plot patterns on the A-CN-K diagram also nearly endorse CIA based interpretation. These rocks possess relatively high Th/U ratios compared to that found in fresh igneous rocks or their high grade metamorphic equivalents. This high Th/U ratio is neither a source inheritance nor a result of oxidation state rather a manifestation of Th hosting mineral accumulation through sorting. Viewed in the context of present stratigraphic succession, the weathering history adduced from geochemistry does not seem compatible but matches well with earlier classification scheme wherein the evolution of Aravalli Supergroup was considered episodic.

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Section: Th/u Ratiomentioning

confidence: 99%

Geochemistry of Palaeoproterozoic Rocks of Aravalli Supergroup: Implications for Weathering History and Depositional Sequence

Singh¹,

Khan²

2017

IJG

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“…The natural sources of arsenic compounds are mainly released from volcanic activity, since they are widely distributed in the earth's crust (2 mg/kg) (Wedepohl, 1991). Throughout the related high temperature processes, some arsenic compounds are adsorbed on volcanic ash and deposited to the ground, while the others remain in atmospheric aerosols, and these are then subject to longrange transportation in the troposphere (Thomaidis et al, 2003;Wang et al, 2010;Chen et al, 2012;Fang et al, 2012a).…”

Section: Introductionmentioning

confidence: 99%

Atmospheric Arsenic Deposition in Chiayi County in Southern Taiwan

Lin

et al. 2013

Aerosol Air Qual. Res.

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Although arsenic contamination of underground water in southern Taiwan is well known, few studies examine atmospheric arsenic deposition in this area, which might be the major source of such pollution to the soil, water, and even underground water. This research focused on the atmospheric arsenic concentration, dry and wet depositions, and the As distribution around Chiayi County, located in the south of Taiwan. Eight sampling sites are used, both upwind and downwind of an area with heavy industrial and human activities. All samples were collected by a PS-1 high volume sampler at each site, pretreated by a digestion process, and further analyzed with an ICP-MS. The results show that the arsenic deposition flux ranged from 65.0 to 473 μg/m 2 -month in Chiayi County. This deposition flux has no significant seasonal variation, based on the multiple trend results obtained from pooling the dry and wet deposition data. The average dry deposition flux of As ranged from 34 to 161 μg/m 2 -month during the sampling year, and had the opposite trend to the wind speed. Additionally, the correlations between atmospheric arsenic concentration and PM levels were significant, supported by the low p-value (< 0.01) at a 99% confidence level. Meanwhile, the highly linear correlation between As and PM concentrations was also evaluated. The amount of precipitation was statistically correlated to the wet deposition flux (11.3-414 μg/m 2 -month with a p-value = 2 × 10 -7 and r-value = 0.9306. Furthermore, the composition of the As mass concentrations in ambient air were dominated by As (V) in both fall (66.4%) and winter (68.9%). According to the GIS spatial analysis of the As concentration in the dry season, from October to March, the As contribution of local emissions were not significant. Consequently, this study indicates that the atmospheric As around Chiayi County might be sourced from the upwind northern area, and mainly deposited through wet scavenging.

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“…Contents of major, minor and trace elements in the studied material were compared to those in the standard sediments: Post-Archean Australian Shale (PAAS after Taylor & McLennan 1985), average shales (Wedepohl 1991) …”

Section: Samples and Methodsmentioning

confidence: 99%

Source areas of the Grybów sub-basin: micropaleontological, mineralogical and geochemical provenance analysis (Outer Western Carpathians, Poland)

Oszczypko-Clowes¹,

Wójcik-Tabol²,

Płoszaj³

2015

Geologica Carpathica

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Abstract:The Grybów Unit occurring in the Ropa tectonic window was the subject of micropaleontological and geochemical investigation. Studies, based on calcareous nannofossils, proved that the level of reworked microfossil is not higher than 22 % and it varies between two sections. Quantitative analyses of the reworked assemblages confirmed the domination of Cretaceous and Middle Eocene species. The Sub-Grybów Beds, Grybów Marl Formation and Krosno Beds were assigned to the Late Oligocene and represent the terminal flysch facies. Detrital material accumulated in the Oligocene sediments originated from the Marmarosh Massif, which is the eastern prolongation of the Fore-Magura Ridge

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Chemical composition and fractionation of the continental crust

Cited by 161 publications

References 46 publications

Geochemistry of Palaeoproterozoic Rocks of Aravalli Supergroup: Implications for Weathering History and Depositional Sequence

Geochemistry of Palaeoproterozoic Rocks of Aravalli Supergroup: Implications for Weathering History and Depositional Sequence

Atmospheric Arsenic Deposition in Chiayi County in Southern Taiwan

Source areas of the Grybów sub-basin: micropaleontological, mineralogical and geochemical provenance analysis (Outer Western Carpathians, Poland)

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