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Volume 18 (1984)
- Issue 6 Pages 269-
- Issue 5 Pages 217-
- Issue 4 Pages 167-
- Issue 3 Pages 101-
- Issue 2 Pages 45-
- Issue 1 Pages 1-
Volume 18, Issue 2
Displaying 1-6 of 6 articles from this issue
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Chihiro Sakai, Toshio Higashino, Masaki Enami1984 Volume 18 Issue 2 Pages 45-53
Published: April 20, 1984
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSEpidote, which contains significant amounts of rare earth elements and thorium, and allanite occur in the Sanbagawa pelitic schists of central Shikoku at all the metamorphic grades. Petrographical and chemical studies suggest a metamorphic origin of the REE-bearing epidote and a detrital origin of the allanite. The detrital allanite is the major source of REE and Th in the metamorphic epidote.View full abstractDownload PDF (3111K) -
P. K. Kuroda, John C. H. Liou, Ashok D. Banavali, John D. Akridge, Lar ...1984 Volume 18 Issue 2 Pages 55-60
Published: April 20, 1984
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSThe amount of excess 210Po activity injected into the atmosphere by the 18 May 1980 eruption of Mount St. Helens was greater than that of 90Sr released by the 16 October 1980 Chinese test explosion of a 0.2 to 1 megaton nuclear device. The occurrence of a ‘mystery’ cloud prior to the 28 March 1982 eruption of El Chichón volcano was accompanied by an increase in the 210Po/210Pb ratio in rain samples collected at Fayetteville, Arkansas, during the months of January and February, 1982.View full abstractDownload PDF (1291K) -
Hideki Wada, Masaki Enami, Takeru Yanagi1984 Volume 18 Issue 2 Pages 61-73
Published: April 20, 1984
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSCarbon, oxygen and strontium isotopic studies were carried out on marbles occurring in crystalline schists and epidote amphibolites of the Sanbagawa metamorphic terrain, central Shikoku, Japan, in order to estimate metamorphic temperatures and to elucidate their origin. Carbon isotopic fractionation between calcite and graphite shows the metamorphic temperature of 460°C at the transitional part between the garnet and albite-biotite zones. Marbles are isotopically classified into two groups. (1) some marbles in epidote amphibolite masses show characteristically negative δ13C values and low 87Sr/86Sr ratios. These marbles are interpreted as have been derived from magmatic or deep-seated carbonates. (2) marbles collected from the crystalline schists and from the marginal part of epidote amphibolite masses, have high 87Sr/86Sr ratios and δ13C values similar to those of typical sedimentary carbonates. They were probably derived from sedimentary carbonates and/or carbonates re-equilibrated with metamorphic fluid segregated from crystalline schists during the Sanbagawa metamorphism.View full abstractDownload PDF (4337K) -
Tadashi Miyoshi, Hitoshi Sakai, Hitoshi Chiba1984 Volume 18 Issue 2 Pages 75-84
Published: April 20, 1984
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSSulfur isotope fractionation factors between sulfate and sulfide at 600 to 1, 000°C were experimentally determined by decomposing anhydrous Na2SO3 in melts of NaCl and LiCl-KCl mixture (6 : 4 molar ratio). Sulfur isotope exchange equilibrium was attained between sulfate and sulfide formed by decomposition of sodium sulfite within 120 minutes at 600°C in the LiCl-KCl melt and within 30 minutes at 810°C in the NaCl melt. The observed fractionation factors (α) obey the relationship in the experimental temperature range: 1000 lnαsulfate-sulfide = 7.4 × 106/T2 − 0.19. In alkali chloride melts, sulfide would exist as HS-, S2-, NaHS and NaS-, and sulfate as SO42- and NaSO4-, respectively, in an analogy with aqueous sodium chloride solution. The observed fractionation factors are considered to represent those between bulk sulfate and sulfide ions. The fractionation factor between gaseous H2S and dissolved sulfate in melt at 600 and 700°C is about 1 and 0.7‰ smaller than those between dissolved sulfide and sulfate in melt, respectively, and may be approximated by the following equation in the experimental temperature range: 1000 lnαsulfate-H2S = (6.5 ± 0.3) × 106/T2.View full abstractDownload PDF (2576K) -
Hisayoshi Yurimoto, Shigeho Sueno1984 Volume 18 Issue 2 Pages 85-94
Published: April 20, 1984
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSPartition coefficients for -1, -2, -3, +1, +2, +3, +4 and +5 valent ions between the groundmass of tholeiite basalt and coexisting olivine and plagioclase phenocrysts from the Mid-Atlantic Ridge have been determined by secondary ion mass spectrometry. The present cation partitioning strongly supports the “crystal structure control” mechanism. The partition coefficient for an anion is also under control of the crystal structure, so that each of the cation and anion positions in the crystal structure gives rise to a parabola-shaped peak on the partition coefficient vs. ionic radius diagram.View full abstractDownload PDF (2671K) -
Ken-ichiro Aoki, Hajime Kurasawa1984 Volume 18 Issue 2 Pages 95-100
Published: April 20, 1984
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSThe 87Sr/86Sr ratios of six representative tephrite series rocks, including 1981–1982 lavas, from Nyamuragira volcano, Western Rift have been determined. The range and average of the ratios are from 0.70543 to 0.70587 and 0.70572, and agree well with those of ugandite from the Western Rift (0.7054–0.7059 and 0.7056) reported by BELL and POWELL (1969) and POWELL and BELL (1974). Petrological and geochemical data suggest that the tephrite series, olivine basanite–tephrite–phonolitic tephrite–tephritic phonolite are products of successive fractionation of a parental ugandite magma (AOKI et al., 1984). These isotopic results support strongly this conclusion.View full abstractDownload PDF (1535K)
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