The superparamagnetism of Yucca Mountain Tuff

Worm, Horst-Ulrich; Jackson, Mike

doi:10.1029/1999jb900285

Cited by 133 publications

(181 citation statements)

References 24 publications

Supporting

Mentioning

169

Contrasting

Order By: Relevance

“…Recent studies show that higher χ fd (%) is associated with the narrower size distributions of SP+SD particles, i.e. χ fd (%) is inversely related to the width of grain size distribution [26,27] . Notably, recent mineral magnetic results by Liu et al [10,11] by using a series of measurements on magnetic extracts clearly indicate that in the western CLP: 1) ARM is dominantly carried by SD grains; 2) with moderate degree of pedogenesis (χ < 10×10 −7 m 3 /kg), χ is enhanced more by increasing concentration of SSD magnetic grains than by viscous SP grains; 3) for more mature paleosols (χ > 10-12×10 −7 m 3 /kg), contribution of pedogenically related fine-grained PSD grains becomes significant.…”

Section: Discussionmentioning

confidence: 97%

Environmental magnetism and paleoclimatic interpretation of the Sanmenxia loess-paleosol sequence in the southeastern extremity of the Chinese Loess Plateau

et al. 2006

View full text Add to dashboard Cite

This is a report of multi-parameter mineral magnetic results of the Sanmenxia loess-paleosol couplets in the SE extremity of the Chinese Loess Plateau (CLP) over the interval of L1-L13 spanning the last 1 Ma. These results show that mass-specific magnetic susceptibility (χ), χ ARM and SIRM and their ratios exhibit parallel stratigraphic variations. Since superparamagnetic (SP) particles have significant contribution to χ but no contribution to remanence, e.g., ARM and SIRM, the strong linear correlations between χ and remanence (e.g., ARM and SIRM) suggest that the pedogenesis-produced magnetic grains are predominantly in small single domain range. Consequently, the significant contribution of SP particles to the bulk χ as supposed in previous studies has been obviously overestimated.χ ARM /χ data in Sanmenxia and median grain size records of typical loess sections from the hinterland of the CLP display a strong resemblance, implying that χ ARM /χ may be regarded as a reliable indicator for monitoring the variations of ferrimagnetic grain sizes. The results of S-ratio and HIRM ((SIRM+IRM −0.3T )/2) measurements indicate that there is significant enhancement of both soft magnetite/maghemite and hard hematite/goethite in paleosols associated with pedogenesis.Presently it is widely accepted that the enhancement of magnetic susceptibility for the Chinese loess-paleosol sequences is primarily due to the formation of ultrafine magnetic particles through pedogenesis [1] . However, there still exist controversies on both the actual contribution of pedogenesis-produced superparamagnetic (SP) particles to the total magnetic susceptibility and the process whereby climate change is encoded in magnetic susceptibility signals [ ] 2-5 . Relying on a specific multiple regression technique to fit the experimental isothermal and anhysteretic remanent magnetization data to corresponding data for synthetic analogues, Maher and Thompson [6] demonstrate that the contribution of magnetite in soils is twice as much as in loess, and over 90% of the susceptibility contrast between soil and loess is due to magnetic grains lying near the SP threshold. Based on low-temperature saturation remanence magnetization analysis, Banerjee and Hunt [7] suggest that the ratios of SP/total saturation remanence at 15 K are as high as about 0.75 in soil but only 0.2 in loess. Results of detailed magnetic susceptibility measurements and grain size analysis by Han and Jiang [8] suggest that the very fine-grained particles (<0.3 μm), which are considered to be of pedogenic origin, contribute little to the bulk magnetic susceptibility, no more than 3%. Recently, Liu et al. [9 11] report thorough enquiries into the grain-size distribution, concentration and enhancement mechanisms of magnetic minerals in Chinese loess by a series of fruitful rock magnetic measurements. These detailed mineral magnetic results from the western Chinese Loess Plateau (CLP) suggest that: 1) single-domain (SD) magnetic particles contribute more than half of the magnetic susceptibi...

show abstract

Section: Discussionmentioning

confidence: 97%

Environmental magnetism and paleoclimatic interpretation of the Sanmenxia loess-paleosol sequence in the southeastern extremity of the Chinese Loess Plateau

et al. 2006

View full text Add to dashboard Cite

show abstract

“…Only one regression line is shown because those for the two soils were not significantly different. fine ferrimagnets around the SP/SD boundary is inversely related to χ FD % (Worm, 1998;Worm and Jackson, 1999).…”

Section: Grain Size Distribution Of Maghemitementioning

confidence: 97%

“…χ FD % is known to depend mainly on the GSD of nanosized magnetic particles (Worm, 1998;Worm and Jackson, 1999), so only particles around the SP/SD threshold are in a viscous SP (VSP) state which is seemingly sensitive to the experimental frequency. As a corollary, if the GSD is similar for a set of samples, then the absolute value of the frequency-dependent χ, χ FD , can be used as a proxy for the concentration of ferrimagnets.…”

Section: Grain Size Distribution Of Maghemitementioning

confidence: 99%

Magnetic minerals in Calcic Luvisols (Chromic) developed in a warm Mediterranean region of Spain: Origin and paleoenvironmental significance

2010

View full text Add to dashboard Cite

“…are 17.31 and 21.99 × 10 − 8 m 3 kg − 1 , respectively. χ FD % (defined as (χ LF -χ HF )/χ LF × 100%) is controlled by both the grain size distribution (GSD) of the superparamagnetic (SP) + single domain (SD) particles (Eyre, 1997;Worm, 1998;Worm and Jackson, 1999), and the relative concentration of SP + SD and pseudo-single domain (PSD) particles. For a soil profile, the linear fitting slope of χ-χ FD scatter plot is a good indicator of the average grain size of this profile without the effect of MD (multi-domain) particles.…”

Section: Magnetic Properties Of the Loess Sequences (L1-s5)mentioning

confidence: 99%

Quantifying paleoprecipitation of the Luochuan and Sanmenxia Loess on the Chinese Loess Plateau

Liu

Wei

Wang

et al. 2016

Palaeogeography, Palaeoclimatology, Palaeoecology

View full text Add to dashboard Cite

The superparamagnetism of Yucca Mountain Tuff

Cited by 133 publications

References 24 publications

Environmental magnetism and paleoclimatic interpretation of the Sanmenxia loess-paleosol sequence in the southeastern extremity of the Chinese Loess Plateau

Environmental magnetism and paleoclimatic interpretation of the Sanmenxia loess-paleosol sequence in the southeastern extremity of the Chinese Loess Plateau

Magnetic minerals in Calcic Luvisols (Chromic) developed in a warm Mediterranean region of Spain: Origin and paleoenvironmental significance

Quantifying paleoprecipitation of the Luochuan and Sanmenxia Loess on the Chinese Loess Plateau

Contact Info

Product

Resources

About