Study of colors and degrees of weathering of granitic rocks by visible diffuse reflectance spectroscopy.

Nagano, Tetsushi; Nakashima, Satoru

doi:10.2343/geochemj.23.75

Cited by 57 publications

(28 citation statements)

References 7 publications

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“…Iron oxide minerals can be both pedogenic (i.e., a product of soil formation) and lithogenic (i.e., unweathered minerals from the parent material) in origin (Cornell & Schwertmann, 2003;van Dam et al, 2006;Lu et al, 2008). Magnetic susceptibility gives an approximate indicator of concentration of the ferrimagnetic minerals in the soil, thus a close relationship between iron content, soil colour and magnetic susceptibility is observed/expected (e.g., Nagano & Nakashima, 1989;Hanesch & Scholger, 2005). For example, Allan (1986) found a close relation between soil colour and magnetization for samples from mafic rocks but not for those from other rocks.…”

Section: Soil Colour Determinationmentioning

confidence: 99%

Magnetic Susceptibility of Soils from Eastern Botswana: A Reconnaissance Survey and Potential Applications

Ranganai¹,

Moidaki²,

King³

2015

JGG

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Soil magnetic properties measurements are relatively fast and inexpensive but have been proved to be sufficient for preliminary investigations in diverse socio-developmental issues. This paper presents results of a reconnaissance study of soil colour and magnetic susceptibility (χ) in eastern Botswana, where ~80% of the population resides. The work is a first step to creating a database of rock and soil magnetic properties and to document spatial variations in magnetic properties in the country. These measurements are important as constraints for interpretation of available aeromagnetic data and can also be exploited for environmental soil research (pollution) and land-use planning (agriculture). The soils sampled include derivatives of varying types and provenance such as Archean gneissic granitoids, metamorphosed rocks (granulites), volcano-sedimentary assemblages, Karoo basalts, and alluvial sediments. A soil colour chart was used since soil colours and magnetic properties are diagnostic of its parent rock sources and weathering profiles. Soil magnetic susceptibilities were measured at both low frequency (0.46 MHz, χlf) and high frequency (4.6 MHz, χhf), thus allowing calculation of frequency-dependent susceptibility (χfd, χfd%) for detecting ultra-fine ferromagnetic minerals.It was found that soils with Hues ranging from 7.5YR to 10YR have appreciable amount of magnetic materials and soils with Hues of 2.5YR are generally nonmagnetic. The results of soil magnetic susceptibility profiles show spatial variation closely related to the variation in basement rocks, which provides excellent evidence that the magnetic susceptibility variation reflects basement rocks or bedrock composition (soil parent material). In relation to the Botswana physiographic units, soils from the hardveld (Precambrian) show the highest susceptibilities, followed by those from the sandveld, with the lowest values being from the alluvial. The frequency dependent magnetic susceptibilities indicate the presence of ultra-fine super-paramagnetic minerals such as magnetite/maghemite. It is suggested that a systematic and continuous programme of rock and soil magnetic measurements would benefit various socio-economic and development priority sectors of Botswana. This also applies to many developing countries in Africa where soil physics and measurement of soil susceptibility in particular, is generally still at an embryonic stage.

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Section: Soil Colour Determinationmentioning

confidence: 99%

Magnetic Susceptibility of Soils from Eastern Botswana: A Reconnaissance Survey and Potential Applications

Ranganai¹,

Moidaki²,

King³

2015

JGG

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“…Spectroscopy can be used for studying these variations in colour of stones. It is also a useful tool to measure the differences by before-after tests and as well as the grade of weathering (Nagano and Nakashima, 1989).…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Discoloration Generated by a CI ICE's Exhaust Gas on Various Stone Types

Farkas

Szabados

Antal

et al. 2018

Period. Polytech. Transp. Eng.

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“…Plus b* values corresponds to yellow, minus ones to blue (Hunt, 1980). This representa tion has already been proven useful for the color determination of powdered rock samples (Nagano and Nakashima, 1989). …”

Section: Methodsmentioning

confidence: 99%

“…kind of instrument is generally used in color quality control operations of wide range of in dustrial products. Nagano and Nakashima (1989) have already pointed out the validity of this colorimeter in quantifying the weathering degrees of powdered granitic rocks having slight yellowish color differences. The present work aims to establish a color measurement method …”

Section: Introductionmentioning

confidence: 99%

A convenient method of color measurement of marine sediments by colorimeter.

Nagao

Nakashima²

1991

Geochem. J.

Self Cite

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A convenient method has been developed for the determination of colors of wet and powdered marine sediments. The colors of the sediments are determined with a simple colorimeter and described in the second CIE 1976 color space (L*a*b* color space) . This method can sensitively detect color differences impossible to detect by the naked eye for wet and powdered sediment samples . It generally gives standard deviations of about 3% for replicate determinations of L*a*b* values for powdered samples of brown, dark brown, and greenish gray sediments , and less than 8% for wet black sediments. The color measurement of wet core samples on board the ship can be rapidly performed by this method , which is much more convenient and quantitative than the conventional visual color description using rock color chart. The effects of water content, grain size and oxidation artifact on color of sediments are also discussed.

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Study of colors and degrees of weathering of granitic rocks by visible diffuse reflectance spectroscopy.

Cited by 57 publications

References 7 publications

Magnetic Susceptibility of Soils from Eastern Botswana: A Reconnaissance Survey and Potential Applications

Magnetic Susceptibility of Soils from Eastern Botswana: A Reconnaissance Survey and Potential Applications

Experimental Investigation of Discoloration Generated by a CI ICE's Exhaust Gas on Various Stone Types

A convenient method of color measurement of marine sediments by colorimeter.

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