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Volume 29 (1995)
- Issue 6 Pages 337-
- Issue 5 Pages 277-
- Issue 4 Pages 213-
- Issue 3 Pages 163-
- Issue 2 Pages 97-
- Issue 1 Pages 1-
Volume 29, Issue 3
Displaying 1-5 of 5 articles from this issue
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Jean-paul Toutain, Jean-paul Quisefit, Pierre Briole, Panaliotis Aloup ...1995 Volume 29 Issue 3 Pages 163-173
Published: June 20, 1995
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSAerosols were sampled at Mount Etna over a five-month period in 1985, enclosing the March-July south upper flank eruption. Collection was performed both at effusive vents by manual sampling during the eruption, and in the summit plume by means of an automatic collector during and after the eruption. The automatic collector allows a regular sampling in the difficult-to-reach summit area. Aerosols were analysed for S, Cl, and some metallic elements by 3 complementary analytical techniques (XRF, PIXE and AAS). Aerosol mineralogy has also been investigated by means of SEM. The analysed elements are emitted with enrichments coherent with the known models dealing with their degree of volatility in magmatic conditions. Sulfuric acid-particle reactions in the summit plume and high-temperature fractionation phenomena cause large discrepancies in the mineralogy and chemistry of particles emitted from the summit craters and lateral vents.View full abstractDownload PDF (2893K) -
Etsuo Uchida, Yuichi Goryozono, Masahiro Naito, Masahito Yamagami1995 Volume 29 Issue 3 Pages 175-188
Published: June 20, 1995
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSAqueous speciation of iron and manganese chlorides in supercritical hydrothermal solutions was determined by monitoring the effects of NaCl and KCl on the Ca/(Ca+Fe) and Ca/(Ca+Mn) ratios of aqueous chloride solutions in equilibrium with scheelite and ferberite and with scheelite and huebnerite, respectively. The experiments were carried out under supercritical conditions of 400 and 600°C, and 1 kbar. The ratios decrease significantly with increasing NaCl and KCl concentrations at both 400°C and 600°C. This is attributable to the formation of higher-order aqueous chloride complexes of Fe and Mn, presumably FeCl3-aq and MnCl3-aq. Based on the thermodynamic analysis of the experimental results using published dissociation constants for NaClaq, KClaq and CaCl2aq, logarithms of the formation constants for FeCl3-aq were obtained to be 0.2(NaCl) and 1.2(KCl) for 400°C, and 1.9(NaCl) and 1.9(KCl) for 600°C, and those for MnCl3-aq to be 0.4(NaCl) and 1.1(KCl) for 400°C and 2.3(NaCl) and 2.3(KCl) for 600°C. This means that the supposition of m(MeCl2aq)=ΣmMe for supercritical hydrothermal solutions is invalid.View full abstractDownload PDF (3293K) -
Hiroshi Naraoka, Keita Yamada, Ryoshi Ishiwatari1995 Volume 29 Issue 3 Pages 189-195
Published: June 20, 1995
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSStable carbon isotopic compositions of individual n-fatty acids ranging from C20 to C30 in a terrestrial (riverine) and a marine (pelagic) sediment were determined using gas chromatography/isotope ratio monitoring mass spectrometry (GC/IRMS). These fatty acids in a terrestrial sediment at the Ohtsuchi river in northern Honshu Island, Japan, showed δ13C values (from -35 to -32‰ relative to PDB) lighter than that of the total organic carbon (TOC; -26.4‰) by about 6 to 9‰. The δ13C values from a marine sediment in the Pacific Ocean ca. 500 km off the coast of Honshu Island varied from -31 to -26‰, which were also lighter than that of the TOC (-20.5‰) by 6 to 9‰. The δ13C values of n-fatty acids ranging from C20 to C30 in the marine sediment were heavier by about 5 to 6‰ than those at the corresponding carbon numbers in the terrestrial one. Isotopically, the marine n-fatty acids were clearly distinguished from the terrestrial ones. These results suggest that long-chain n-fatty acids in marine sediment were not derived from land higher plant but from marine organisms, although long-chain n-fatty acids (≥C20) in marine sediments have often been used to assess terrestrial material contribution to the ocean.View full abstractDownload PDF (2160K) -
Toshiaki Tsunogae, Hisayoshi Yurimoto1995 Volume 29 Issue 3 Pages 197-205
Published: June 20, 1995
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSSingle zircon U-Pb chronology was applied to help understanding the evolution of the Limpopo Belt in southern Africa. High mass resolution (M/ΔM=ca. 6000) obtained by a CAMECA IMS-3F ion microprobe was sufficient to determine Pb/U ratios of zircon crystals without any significant mass interferences. U-Pb ages of euhedral zircons from the belt cluster at around 3.2 Ga for the Central Zone and 2.8 Ga for the Northern Marginal Zone. The difference in age between the two zones can be explained by difference in protolith age. Timing of metamorphism was identified for the Northern Marginal Zone as 2 to 1.7 Ga which is younger than previously reported metamorphic ages of the Limpopo Belt.View full abstractDownload PDF (2427K) -
Takahiro Tagami, Kozo Uto, Takaaki Matsuda, Noriko Hasebe, Akikazu Mat ...1995 Volume 29 Issue 3 Pages 207-211
Published: June 20, 1995
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSK-Ar biotite and fission-track (FT) zircon ages were determined on the Nisatai Dacite (ND), Iwate Prefecture, Japan, to assess its suitability for a geologic age standard. The concentration of potassium and argon isotope ratios were determined on a biotite sample twice and three times, respectively, and yielded reproducible results within analytical errors. A K-Ar age was given as 21.0±0.3 (2 sigma) Ma. FT zircon ages were determined on two samples from different localities as 21.8±1.4 (2 sigma) and 23.9±1.4 Ma. The K-Ar age was obtained from an outcrop adjacent to that for the former FT age, with a good agreement between the two methods. The concordance in age, in conjunction with previous zircon FT length data, suggests a potential applicability of the ND to both the K-Ar and FT system calibration in Cenozoic time.View full abstractDownload PDF (1369K)
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