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Volume 38 (1990)
- Issue 6 Pages 269-
- Issue 5 Pages 241-
- Issue 4 Pages 151-
- Issue 3 Pages 95-
- Issue 2 Pages 65-
- Issue 1 Pages 1-
Volume 38, Issue 3
Displaying 1-7 of 7 articles from this issue
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REGULAR PAPERS
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Masao Nomura, Yasuhiko Fujii, Makoto Okamoto1990 Volume 38 Issue 3 Pages 95-100
Published: 1990
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSIsotopic ratios of boron in typical 5 coals from Japan, Canada, China, South Africa and the U.S.A. have been measured with surface ionization mass spectrometry. The work was performed by obtaining the information about the origin of coals, e.g., marin or non-marin.
The results indicated that the 11B/10B ratio in Taiheiyo Coal (Japan) was a high value of 4.177 which was similar to that in sea water, while the ratios in other 4 coals were lower values of 3.966~4.013. These facts suggest that Taiheiyo Coal deposited through contact with sea water, but others were not, probably contacted with ground water.
As a simulation for the equilibrium between sea water and coal, using activated charcoal, the isotopic fractionation factor was determined to be 1.022.
In the present work the gain of secondary electron mutiplier for the ion beam Na2BO2+ was cofirmed to be inversely proportional to the root of the ion mass.View full abstractDownload PDF (429K) -
Kazuya Takahashi, Akimasa Masuda1990 Volume 38 Issue 3 Pages 101-105
Published: 1990
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSThe 147Sm-143Nd isotopic system has been used as a powerful geochronological tool. Usually the 143Nd abundances has been obtained as the 143Nd/144Nd ratio. In this report, we will propose a new technique to measure 143Nd. In this new method, the amount of 143Nd is measured as the 143Nd/145Nd ratio and the 146Nd/145Nd ratio is used for the correction of mass fractionation. The normalizing value for 146Nd/145Nd ratio has been determined to be 2.07199. This technique will require no separation of Nd from other rare earth elements, since the stable nuclides with mass numbers of 143, 145, and 146 exist only in Nd. Furthermore, it seems that this new technique would be compatible with the old technique, where the data have been obtained as 143Nd/144Nd and normalized to 146Nd/144Nd=0.7219 after complete separation of Nd from mass-spectrometrically interfering REE.View full abstractDownload PDF (365K) -
Hiroshi Shimizu, Hiroshi Amakawa, Hideyuki Sawatari, Akimasa Masuda1990 Volume 38 Issue 3 Pages 107-113
Published: 1990
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSCe and Nd isotopic data of rocks could give information on light-REE patterns of original sources of the rocks. In this paper, mathematical procedures of estimation of chondrite-normalized (La/Ce)N and (Nd/Sm)N values for the sources are presented in detail. Particularly, changes of (138La/142Ce)CHUR and (147Sm/144Nd)CHUR ratios with time are noted.View full abstractDownload PDF (437K) -
Yoshiyuki Nishikawa, Noboru Nakamura, Keiji Misawa, Osamu Okano, Hiroo ...1990 Volume 38 Issue 3 Pages 115-123
Published: 1990
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSIn order to examine weathering effects on chondritic meteorites in Antarctic and non-Antarctic environments, the Rb-Sr isotopic ratios and abundances of REE, Ba, Sr, Rb, and K were determined for 8H-group chondrites (Yamato-790986 [H3], Yamato-74492 [H3], Grady [H3], Brownfield [H3], Clovis (No. 1) [H3], Yamato-74155 [H4], Allegan [H5] [one whole-rock and two chondrules], and Yamato-74371 [H5]), and partly for the Etter (L5) chondrite.
The Allegan whole-rock shows a flat REE pattern with a large negative Eu anomaly and Sr depletion. Analyses of Rb-Sr systematics of one whole-rock and two chondrules show somewhat younger age 4.38±0.12 b.y. It is suggested that REE and Rb-Sr were redistributed during the early thermal metamorphism.
Except for Allegan, most other H-chondrites (finds) show the perturbation of the Rb-Sr systematics, indicating recent loss of Rb. It was found that the weathering degree is related with the Rb-Sr disturbance in Antarctic H-chondrite. In spite of different degrees of weathering, all the Antarctic H-chondrites studied (including heavily weathered ones) show flat REE patterns normal as H-chondrite with occasional occurrence of minor Eu anomalies, indicating the tough resistance of REE in H-chondrites to the Antarctic weathering. On the other hand, non-Antarctic finds (particularly the weathered chondrites) indicate light-REE enriched patterns with a large negative Ce anomaly and extreme enrichment of Ba, suggestive of terrestrial contaminations.View full abstractDownload PDF (688K) -
Role of the Subducting Slab for Magma-Genesis in Island ArcSusumu Nohda, Mitsuhiro Murasaki, Yoshiyuki Tatsumi1990 Volume 38 Issue 3 Pages 125-131
Published: 1990
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSIsotopic compositions of Sr and Nd were determined for the volcanic rocks from the Izu Islands Arc. The volcanic rocks from the volcanic front zone show variable Nd isotopes ranging from 0.513088 to 0.513125 of 143Nd/144Nd with an average εNd of 9.0±0.3, and 87Sr/86Sr from 0.70318 to 0.70355 with an average εSr of -16.1±0.7. The back arc side volcanics show slightly lower Nd and Sr isotopic ratios as 143Nd/144Nd from 0.512994 to 0.513066 with an average εNd of 7.8±0.4 and 87Sr/86Sr form 0.70299 to 0.70325 with average εSr of -19.9±0.4. Across arc isotopic variation of Sr and Nd from the volcanic front to the back-arc side is attributed to difference in the degree that the magmas of the subduction zones are generated by the addition of the fluid which is extracted from the hydrous minerals in the down-going slab. Magmas in the volcanic front are much more affected by the addition of the considerable amount of the fluid than the back-arc side magmas and altered Sr and Nd isotopic compositions from their original values of the mantle wedge. The role of the fluid from the down-going slab for magma generation is isotopically assessed in the intra-oceanic Izu arc, and the Nd and Sr isotopic compositions of the fluid extracted from the down-going slab is equivalent with those of the altered MORB.View full abstractDownload PDF (531K) -
Tsuyoshi Tanaka, Naoyuki Ando, Hikari Kamioka, Shigeko Togashi1990 Volume 38 Issue 3 Pages 133-141
Published: 1990
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSCerium, neodymium and strontium isotopes as well as 33 elements were analyzed for Takla Makan desert sand. The results are discussed in comparison with loess, North American Shale Composite and so-called average amounts of the elements in crustal rocks. Elemental abundances in the desert sand are within 0.3 to 2 times of the crustal values. Large Ion Lithophiles (LIL) like rare earth elements are poor in the desert sand, as compared with loess in China. Fine-grained mesostasis rich in LIL are considered to have been transported as loess from the desert sand. Strontium and neodymium isotopic compositions of the desert sand (εSr(0)=+160, εNd(0)=-12.1) are identical with those of loess in China and Hwang-He suspended particles. These values show continental nature of the sand. 138Ce/142Ce ratio, on the other hand, is smaller than that of chondrite. This suggests that the La/Ce ratio integrated into time and space of China is smaller than that of chondrite.View full abstractDownload PDF (633K) -
Fukue Shirane, Hiroshi Nozaki, Masaaki Ando, Susumu Ohira, Hiroshi Yam ...1990 Volume 38 Issue 3 Pages 143-149
Published: 1990
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSMass spectra of some benzyl methyl sulfones and benzyl methyl thioethers in electron ionization are measured. The mass spectra of two different groups revealed characteristic peaks at [M-79]+ and [M-47]+, respectively.
The compositions of the eliminated radicals were determined by the high resolution mass spectrometry and these fragmentations were discussed on the basis of the linked scan spectra.
It was found that these compounds show main fragmentation pathways by loss of sulfonylmethyl or thiomethyl group to give the corresponding tropylium ions.View full abstractDownload PDF (287K)
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