Correlation of Middle Pleistocene crystal-rich tephra layers from Daisen Volcano, southwest Japan, based on the chemical composition and refractive index of mafic minerals

2011 ◽  
Vol 246 (1-2) ◽  
pp. 105-117 ◽  
Author(s):  
Atsuo Kotaki ◽  
Shigehiro Katoh ◽  
Kanichi Kitani
Keyword(s):  
Refractive Index ◽  
Chemical Composition ◽  
Middle Pleistocene ◽  
Southwest Japan ◽  
Tephra Layers

Chemical Composition of Ice Containing Tephra Layers in the Byrd Station Ice Core, Antarctica

1988 ◽  
Vol 30 (3) ◽  
pp. 315-330 ◽  
Author(s):  
Julie M. Palais ◽  
Philip R. Kyle
Keyword(s):  
Chemical Composition ◽  
Silicate Glass ◽  
Residence Time ◽  
Volcanic Ash ◽  
Global Climate ◽  
Ice Core ◽  
Volcanic Eruptions ◽  
Tephra Layers ◽  
The Antarctic ◽  
Hydrolysis Of

The chemical composition of ice containing tephra (volcanic ash) layers in 22 sections of the Byrd Station ice core was examined to determine if the volcanic eruptions affected the chemical composition of the atmosphere and precipitation in the vicinity of Byrd Station. The liquid conductivity, acidity, sulfate, nitrate, aluminum, and sodium concentrations of ice samples deposited before, during, and after the deposition of the tephra layers were analyzed. Ice samples that contain tephra layers have, on average, about two times more sulfate and three to four times more aluminum than nonvolcanic ice samples. The acidity of ice samples associated with tephra layers is lowered by hydrolysis of silicate glass and minerals. Average nitrate, sodium, and conductivity are the same in all samples. Because much of the sulfur and chlorine originally associated with these eruptions may have been scavenged by ash particles, the atmospheric residence time of these volatiles would have been minimized. Therefore the eruptions probably had only a small effect on the composition of the Antarctic atmosphere and a negligible effect on local or global climate.

scholarly journals Discovery of an early Middle Pleistocene marker tephra around the Ariake Bay area, Southwest Japan

2012 ◽  
Vol 118 (11) ◽  
pp. 709-722 ◽  
Author(s):  
Shoichi Shimoyama ◽  
Hirohisa Matsuura ◽  
Kiyohide Mizuno ◽  
Masakazu Kubota ◽  
Takenori Hino ◽  
...  
Keyword(s):  
Middle Pleistocene ◽  
Ariake Bay ◽  
Southwest Japan ◽  
Bay Area

scholarly journals One year of aerosol refractive index measurement from a coastal Antarctic site

2019 ◽  
Vol 19 (22) ◽  
pp. 14417-14430
Author(s):  
Zsófia Jurányi ◽  
Rolf Weller
Keyword(s):  
Climate Change ◽  
Refractive Index ◽  
Optical Properties ◽  
Chemical Composition ◽  
Seasonal Pattern ◽  
Particle Diameter ◽  
Weddell Sea ◽  
Aerosol Sampling ◽  
Electrical Mobility ◽  
Weather Situation

Abstract. Though the environmental conditions of the Weddell Sea region and Dronning Maud Land are still relatively stable compared to the fast-changing Antarctic Peninsula, we may suspect pronounced effects of global climate change for the near future (Thompson et al., 2011). Reducing the uncertainties in climate change modeling requires a better understanding of the aerosol optical properties, and for this we need accurate data on the aerosol refractive index (RI). Due to the remoteness of Antarctica only very few RI data are available from this region (Hogan et al., 1979; Virkkula et al., 2006; Shepherd et al., 2018). We calculate the real refractive index of natural atmospheric aerosols from number size distribution measurements at the German coastal Antarctic station Neumayer III. Given the high average scattering albedo of 0.992 (Weller et al., 2013), we assumed that the imaginary part of the RI is zero. Our method uses the overlapping size range (particle diameter D between 120 and 340 nm) of a scanning mobility particle sizer (SMPS), which sizes the particles by their electrical mobility, and a laser aerosol spectrometer (LAS), which sizes the particles by their optical scattering signal at the 633 nm wavelength. Based on almost a complete year of measurement, the average effective refractive index (RIeff, as we call our retrieved RI because of the used assumptions) for the dry aerosol particles turned out to be 1.44 with a standard deviation of 0.08, in a good agreement with the RI value of 1.47, which we derived from the chemical composition of bulk aerosol sampling measurements. At Neumayer the aerosol shows a pronounced seasonal pattern in both number concentration and chemical composition. Despite this, the variability of the monthly averaged RIeff values remained between 1.40 and 1.50. Compared to the annual mean, two austral winter months (July and September) showed slightly but significantly increased values (1.50 and 1.47, respectively). The size dependency of the RIeff could be determined from time-averaged LAS and SMPS number size distributions measured between December 2017 and January 2018. Here we calculated RIeff for four different particle size ranges and observed a slight decrease from 1.47 (D range 116–168 nm) to 1.37 (D range 346–478 nm). We find no significant dependence of the derived RIeff values on the wind direction. Thus we conclude that RIeff is largely independent of the general weather situation, roughly classified as (i) advection of marine boundary layer air masses during easterly winds caused by passing cyclones in contrast to (ii) air mass transport from continental Antarctica under southern katabatic winds. Neumayer, the only relevant contamination source, is located 1.5 km north of the air chemistry observatory, where the measurements were performed. Given that northerly winds are almost absent, the potential impact of local contamination is minimized in general. Indeed our data show no impact of local contamination on RIeff. Just in one case a temporary high-contamination episode with diesel engines operating right next to the measurement site resulted in an unusual high RIeff of 1.59, probably caused by the high black carbon content of the exhaust fumes. To conclude, our study revealed largely constant RIeff values throughout the year without any sign of seasonality. Therefore, it seems reasonable to use a single, constant RIeff value of 1.44 for modeling optical properties of natural, coastal Antarctic sub-micrometer aerosol.

scholarly journals Two Contrasting Provenances of Prehistoric Obsidian Artifacts in South Korea: Mineralogical and Geochemical Characteristics

2019 ◽  
Vol 5 (1) ◽  
pp. 106-120 ◽  
Author(s):  
Yong-Joo Jwa ◽  
Seonbok Yi ◽  
Mi-Eun Jin ◽  
Ga-Hyun Hwang
Keyword(s):  
Rare Earth ◽  
Chemical Composition ◽  
Korean Peninsula ◽  
Parental Magma ◽  
Geochemical Characteristics ◽  
The Other ◽  
Southwest Japan ◽  
Glassy Material ◽  
Host Matrix ◽  
Fe Oxides

AbstractTwo provenances – Mount Baekdusan near Sino-Korean border and Kyushu of southwest Japan – are well known for Korean prehistoric obsidian artifacts. We examined the mineralogical and geochemical characteristics of the Baekdusan obsidians and the Kyushu obsidians. Though obsidians are of glassy material, microlites are easily found in the host matrix. Fe-oxides are the most abundant microlite phase, with a lesser amount of clinopyroxene, feldspar, and biotite. It is notable that the texture and chemical composition of the microlites in the Baekdusan obsidians are quite different from those in the Kyushu obsidians. Clinopyroxene in the Baekdusan obsidians occurs as oikocryst enclosing smaller Fe-oxides, and has the composition of hedenbergite to augite. On the other hand, clinopyroxene in the Kyushu obsidians is compositionally of clinoferrosilite, and shows intergrowth and/or overgrowth textures with Fe-oxides. Feldspar microlites in the Baekdusan obsidians are generally of sanidine to anorthoclase, whereas those in the Kyushu obsidians of oligoclase. Biotite microlites are often found in the Kyushu obsidians, but absent in the Baekdusan obsidians. Also, there exist prominent geochemical contrasts between the Baekdusan obsidians and the Kyushu obsidians. At the similar SiO2 range of 74 to 78 wt.% the host glasses of the Baekdusan obsidians have higher contents of TiO2, total FeO, K2O, Nb, Hf, Zr, Ta, Y and rare earth elements (REEs) than those of the Kyushu obsidians. The overall mineralogical and geochemical contrasts for the Baekdusan and Kyushu obsidians seem to reflect different parental magma composition and crystallization environment. This distinction can be used to establish the provenance of the obsidian artifacts from the prehistoric sites in the Korean Peninsula as well as contiguous areas such as China, Japan, and Russia.

The Colorants Effects of Fe2O3 on Borosilicate Glasses Prepared from Subbituminous Fly Ash

2015 ◽  
Vol 1119 ◽  
pp. 731-735
Author(s):  
W. Rachniyom ◽  
Y. Ruangtaweep ◽  
K. Boonin ◽  
K. Phachana ◽  
J. Kaewkhao
Keyword(s):  
Refractive Index ◽  
Fly Ash ◽  
Chemical Composition ◽  
Crystal Structures ◽  
Absorption Spectra ◽  
Borosilicate Glasses ◽  
Ferrous Ions ◽  
Melt Quenching ◽  
Hardness Values

In this work, the subbituminous fly ash (SFA) in Thailand has been investigated for their compositions and crystal structures. Borosilicate glasses were prepare from SFA , B2O3, Na2O and various concentration of Fe2O3 by melt quenching technique. The results have shown that the chemical composition comprised with SiO2, Al2O3 and Fe2O3. The crystal structures of SFA were raised of mullite and quartz phases. The density and refractive index values of glasses were found to increase with increasing of Fe2O3 concentrations. The hardness values have been decreased with increasing of Fe2O3 content. The absorption spectra are corresponding to ferric and ferrous ions in wavelength of 440 nm and 1,050 nm and the color of glasses are green to yellow.

Kingite, a new hydrated aluminium phosphate mineral from Robertstown, South Australia

1957 ◽  
Vol 31 (236) ◽  
pp. 351-357 ◽  
Author(s):  
K. Norrish ◽  
Lillian E. R. Rogers ◽  
R. E. Shapter
Keyword(s):  
Refractive Index ◽  
Chemical Composition ◽  
Specific Gravity ◽  
Diffraction Pattern ◽  
South Australia ◽  
X Ray Diffraction ◽  
Aluminium Phosphate ◽  
X Ray ◽  
Phosphate Mineral ◽  
Hydrated Aluminium

SummaryA new hydrated aluminium phosphate mineral, kingite, from phosphate workings near Robertstown, South Australia, has an idealized formula Al2O3.Al(OH)3.P2O5.9H2O, with some replacement of OH by F. The specific gravity is 2·2 to 2·3, refractive index 1·514, and percentage chemical composition Al2O3 31·92, P2O5 28·63, H2O 37·93. The three strongest lines on the X-ray diffraction pattern are 9·1, 3·45, and 3·48 Å. Kingite changes to a less hydrated phase between 154° C. and 163° C., which is also considered to be a new aluminium phosphate (meta-kingite) with idealized formula Al2O3.Al(OH)3.P2O5.4H2O. The strongest lines of its X-ray diffraction pattern are at 7·4, 5·02, and 37·19 Å.

Nigerite from Lixa, near Felgueiras, Douro Litoral province, Portugal

1965 ◽  
Vol 34 (268) ◽  
pp. 482-486 ◽  
Author(s):  
R. Van Tassel
Keyword(s):  
Refractive Index ◽  
Chemical Composition ◽  
X Ray ◽  
Optical Character ◽  
Hexagonal Crystals

SummaryNigerite occurs in pegmatite as hexagonal crystals enclosed in mica or in association with lithiophilite, apatite and vivianite. Absolute hexagonal parameters are a 5·67 and c 13·88 Å. Powder data are given. Forms and present besides the well-developed {0001}. Density 4·25. Refractive index 1·80, birefringence about 0·005, negative optical character. The chemical composition is studied by means of chemical, X-ray fluorescence and optical spectrography methods.

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