Mineralogical and geochemical studies of glacial sediments from Schirmacher Oasis, East Antarctica

Srivastava, Ashok; Randive, Kirtikumar; Khare, Neloy

doi:10.1016/j.quaint.2012.07.028

Cited by 34 publications

(12 citation statements)

References 21 publications

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“…The intensity and duration of weathering in clastic sediments can also be evaluated by examining the relationship between alkali and alkaline earth elements (Nesbitt and Young, 1982). The chemical index of alteration is one of the most widely used index [CIA = (Al 2 O /Al 2 O 3 + CaO * + Na 2 O + K 2 O)  100, using molecular proportions] with higher values suggesting more intense chemical weathering (Fadipe et al, 2011;Jayaprakash et al, 2012;Srivastava et al, 2012;Újvári et al, 2012). The CaO * represents CaO from the silicate fraction.…”

Section: Weathering and Sediment Recyclingmentioning

confidence: 99%

Geochemistry of the Jurassic and Upper Cretaceous shales from the Molango Region, Hidalgo, eastern Mexico: Implications for source-area weathering, provenance, and tectonic setting

Armstrong‐Altrin

Nagarajan

Madhavaraju

et al. 2013

Comptes Rendus. Géoscience

172

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The weathering conditions, provenance, and tectonic setting of shales from the Pimienta (PF; upper Jurassic), Huayacocotla (HF; lower Jurassic), and Méndez Formations (MF; upper Cretaceous) of the Molango Region, Hidalgo, Mexico have been studied for the first time using mineralogy, major, and trace element data. The X-ray diffraction (XRD) data reveals that the shales consist mostly of illite and muscovite clay minerals. The SEM-EDS study indicates that the PF and HF shales are rich in phosphate minerals and MF shales are abundant in zircon mineral. The chemical index of alteration (CIA  59 to 93) and their position in the A-CN-K (Al 2 O 3-CaO + Na 2 O-K 2 O) ternary diagram point to moderate to intense weathering in the source region. The La/Sc, Th/Sc, and La/Co ratios are more enriched and the Cr/Th and Eu/Eu * ratios are more depleted in MF shales than in the PF and HF shales, indicating derivation from a more felsic source than the PF and HF shales. Similarly, the average Zr content in MF shales (475 ± 185) is higher than in PF (133.9 ± 9.3) and HF shales (139.6 ± 18.2), which suggests a more enriched concentration of zircon mineral among the MF than the other shales (F calc = 32.9820669 and (F crit) 99% = 6.48949, where F calc > (F crit) 99% indicates that data populations are significantly different at 99% confidence level). The LREE enrichment, flat HREE, and negative Eu anomalies in chondrite-normalized plots are attributed to felsic source rock characteristics for the three groups of shales. The trace element concentrations point to an extensional setting (passive margin) for the Jurassic shales (PF and HF) and an active margin setting for the Cretaceous shales (MF).

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Section: Weathering and Sediment Recyclingmentioning

confidence: 99%

Geochemistry of the Jurassic and Upper Cretaceous shales from the Molango Region, Hidalgo, eastern Mexico: Implications for source-area weathering, provenance, and tectonic setting

Armstrong‐Altrin

Nagarajan

Madhavaraju

et al. 2013

Comptes Rendus. Géoscience

172

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“…The CaO* content was calculated using following methods: a) if the content of CaO was less or equal to the Na 2 O content, then we use the CaO value for further calculation, b) if the CaO content was higher than Na 2 O, then Na 2 O value was considered as CaO* value (Bock et al, 1998;Gallet et al, 1998;Roddaz et al, 2006;Újv ari et al, 2008). The higher CIA values (76e100) in the sedimentary rocks suggest the intense chemical weathering in the source region (Fadipe et al, 2011;Srivastava et al, 2013;Ujvari et al, 2013), whereas low values (50 or less) indicate the near absence of chemical weathering and also reflect cool and arid conditions (Fedo et al, 1995).…”

Section: Source-area Weatheringmentioning

confidence: 99%

Provenance and tectonic settings of sands from Puerto Peñasco, Desemboque and Bahia Kino beaches, Gulf of California, Sonora, México

Madhavaraju

Tom

Lee

et al. 2016

Journal of South American Earth Sciences

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“…Hitherto, surface sediments from different lakes in Schirmacher Oasis (SO) have been analyzed for particle size, mineralogy, the morphological features of quartz grains, and elemental geochemistry (Shrivastava et al 2012;Srivastava et al 2013 and references therein; Ravindra 2020). These techniques were employed to understand sediment provenance and the sedimentary processes that were taking place within the lake system and in its catchment.…”

Section: Introductionmentioning

confidence: 99%

Magnetic properties of surface sediments in Schirmacher Oasis, East Antarctica: spatial distribution and controlling factors

et al. 2020

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Purpose We investigated the magnetic properties (abundance, grain size, and mineralogy) of iron oxides present in Lake L-55 sediments, Schirmacher Oasis, East Antarctica, with an aim to understand their spatial distribution and the underlying mechanisms that control their formation and distribution. Methods Twenty-five surficial sediments retrieved from different parts of Lake L-55 were subjected to the entire range of environmental magnetic (magnetic susceptibility, anhysteretic remanent magnetization (ARM), isothermal remanent magnetization (IRM)) measurements (at different field strengths). Inter-parametric ratios (χARM/SIRM, χARM/χlf, χARM/χfd, IRM20 mT/SIRM, IRM20 mT/ARM, S-ratio, L-ratio) provided insights into the magnetic properties (abundance, grain size, and mineralogy of iron oxides). Scanning electron microscopic-energy dispersive X-ray spectroscopic (SEM-EDS) analysis was performed on magnetic extracts from a few sediments. Besides, organic matter (%) was also calculated for the sediment samples. Principal component analysis was performed to gain information on the presence of different components and their relative dominance. Results The iron oxides are strongly magnetic (high values of concentration-dependent parameters). The principal iron oxide is magnetite (S-ratio > 0.90) which is coarse-grained (multi-domain (MD) and stable single-domain (SSD) grains), and there is no influence of authigenic greigite, bacterial magnetite, and anthropogenic magnetite. The mineralogy is confirmed by SEM-EDS data. The iron oxides are of different grain sizes, and their contribution is in the order of MD > SSD > SP as shown by the principal component analysis. Pedogenic iron oxide minerals seem to be present in the samples whose formation is due to the oxidation of magnetite into hematite. However, they are of SSD size and not SP, suggesting that the intensity of pedogenesis is not sufficient to form SP grains. Conclusion The iron oxide minerals are mainly terrigenous, and the biogenic activity within the lake is not sufficient to modify the ferrimagnetic minerals. Spatial distribution patterns suggest the non-uniform distribution of magnetite/titanomagnetite of varying sizes in the lake basin which is transported by both melt water streams and winds.

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Mineralogical and geochemical studies of glacial sediments from Schirmacher Oasis, East Antarctica

Cited by 34 publications

References 21 publications

Geochemistry of the Jurassic and Upper Cretaceous shales from the Molango Region, Hidalgo, eastern Mexico: Implications for source-area weathering, provenance, and tectonic setting

Geochemistry of the Jurassic and Upper Cretaceous shales from the Molango Region, Hidalgo, eastern Mexico: Implications for source-area weathering, provenance, and tectonic setting

Provenance and tectonic settings of sands from Puerto Peñasco, Desemboque and Bahia Kino beaches, Gulf of California, Sonora, México

Magnetic properties of surface sediments in Schirmacher Oasis, East Antarctica: spatial distribution and controlling factors

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