Factors governing abundance of hydrolyzable amino acids in the sediments from the N.W. European Continental Margin (47–50°N)

Boski, Tomász; Pessoa, João Costa; Pedro, Paulo; Thorez, Jacques; Dias, João Alveirinho; Hall, Ian Robert

doi:10.1016/s0079-6611(98)00032-9

Cited by 65 publications

(35 citation statements)

References 21 publications

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“…Following the procedures of Fagel et al (2003), the intensity of the reflections was measured and the correction factors for the semi-quantitative analysis were determined; the results are listed in Table 1. Boski et al (1998) claimed that any abnormal increase in background around 4.04 Å can be regarded as opal. Typically, the normal background level is averaged by using samples from adjacent diatom-barren intervals.…”

Section: Methodsmentioning

confidence: 99%

Mineralogical and geochemical changes in the sediments of the Okhotsk Sea during deglacial periods in the past 500 kyrs

Liu

Song

Lee

et al. 2006

Global and Planetary Change

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Section: Methodsmentioning

confidence: 99%

Mineralogical and geochemical changes in the sediments of the Okhotsk Sea during deglacial periods in the past 500 kyrs

Liu

Song

Lee

et al. 2006

Global and Planetary Change

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“…In the bulk sample, the semi-quantitative relative abundance of minerals was estimated using the height of a diagnostic peak multiplied by a corrective factor [13,14,15] together with the socalled 100% approach (the term 100% approach connotes that the sum of all phase quantities identified in a sample is 100%). The common reflection of clays at 4.47Å is multiplied by a corrective factor of 20 to give estimate of the total clays in the bulk sample ( Table 2).…”

Section: Analytical Techniquesmentioning

confidence: 99%

The Ndop plain clayey materials (Bamenda area – NW Cameroon): Mineralogical, geochemical, physical characteristics and properties of their fired products

Yongue-Fouateu

Ndimukong

Njoya

et al. 2016

Journal of Asian Ceramic Societies

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a b s t r a c tThe physicochemical, mineralogical and technological properties of clayey materials from the Ndop plain (NW Cameroon) have been investigated, for their ceramic applications. The clayey materials have mixed facies with colour ranging from brown, grey, mottled and yellowish brown. The thickness of the exploitable clay layer is more than 5 m. Their mineralogical constituents are quartz, kaolinite, illite and feldspars, with kaolinite as major clay mineral. Based on the geochemistry, their source rocks might be felsic, with a mafic rock inference. These materials display high percentage in fine particles and high Atterberg limits. For all the firing temperatures, flexural strength (1.2-11 MPa), water absorption (8.03-24.27%), linear shrinkage (2.10%), weight loss (4.88-16.54%) and bulk density (1.57-2.03 g/cm 3 ) indicate good ceramic properties for firing samples between 900 and 1100 • C. Most of the fired test bricks show a brick red colour with good to very good cohesion. The studied clays were thus, suitable as raw materials for roof tiles, light weight blocks and hollow bricks; however, mixing of high clayey and highly silty materials could improve the quality of the products.

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“…The powder was placed in an Al sample holder, using gentle pressure to limit any clay mineral orientation. Semi-quantitative estimation was obtained by applying to the measured intensity of the reflections the correction factors determined by Cook et al (1975) and modified by Boski et al (1998) (Fig. 3).…”

Section: Bulk Fractionmentioning

confidence: 99%

“…The usual background level has been averaged by using samples from adjacent diatom-barren intervals. Biogenic opal abundance has been determined by multiplying by 20 the height of the 4.04 Å reflection above the reconstructed background (Boski et al, 1998). The accuracy of the XRD opal content estimation has been tested by comparing those values with direct opal measurement by spectrophotometry after Na 2 CO 3 leachings (see Section 3).…”

Section: Bulk Fractionmentioning

confidence: 99%

Late Quaternary clay mineral record in Central Lake Baikal (Academician Ridge, Siberia)

Fagel

Boski

Likhoshway

et al. 2003

Palaeogeography, Palaeoclimatology, Palaeoecology

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We investigated the mineralogical composition of two cores recovered on the Academician Ridge (Central Lake Baikal, Siberia). Sedimentological features show that the cores are unaffected by turbidity currents. However, hemipelagic deposition is not continuous, but intermittently disturbed by syn-or post-sediment reworking (e.g., bioturbation, slumps, faulting). Such modes of deposition are consistent with the complex uplift history of the ridge. Bulk mineralogy suggests that terrigenous sediment supplies are constant through glacial/interglacial stages, and diluted by diatom-rich intervals related to warmer interglacial stages. The core stratigraphy is based on the correlation of the diatom zonation and opal abundance with the marine oxygen isotope reference curve SPECMAP. The ~ 8-m cores partly recover the last four interglacial/glacial cycles, i.e., since oxygen isotope stage 8. We test the use of clay minerals as a proxy for paleoclimatic reconstruction. The clays are more weathered during the diatom-rich intervals in agreement with warmer climate conditions. However, the mean clay composition does not change significantly through glacial/interglacial stages. This observation implies that, in the Academician Ridge sediments, a simple smectite/illite ratio (S/I) does not alone provide a reliable indicator of climatic variation. It reflects the complex clay assemblages, especially the smectite group, delivered to Central Lake Baikal. Smectites include primarily illitesmectite mixed layers, made of a mixture of montmorillonite and beidellite. According to their behavior after cation saturation, the illite-smectite mixed layers are primarily transformed smectites, with some neoformed smectites intermittently observed. In addition, Al-smectites occur in minor proportions. We conclude that the S/I ratio has a climatic significance only if it evolves in parallel with the weathering stage of the clays and is confirmed by a change in the composition of the smectites.

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Factors governing abundance of hydrolyzable amino acids in the sediments from the N.W. European Continental Margin (47–50°N)

Cited by 65 publications

References 21 publications

Mineralogical and geochemical changes in the sediments of the Okhotsk Sea during deglacial periods in the past 500 kyrs

Mineralogical and geochemical changes in the sediments of the Okhotsk Sea during deglacial periods in the past 500 kyrs

The Ndop plain clayey materials (Bamenda area – NW Cameroon): Mineralogical, geochemical, physical characteristics and properties of their fired products

Late Quaternary clay mineral record in Central Lake Baikal (Academician Ridge, Siberia)

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