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Volume 14, Issue 1
Displaying 1-10 of 10 articles from this issue
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Hiroshi Nagasawa, Kazuo Yamakoshi, Hideo Higuchi1980 Volume 14 Issue 1 Pages 1-10
Published: 1980
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSA technique of neutron activation analysis was developed for nondestructive analysis of small extraterrestrial grain samples of less than 1 mg. The features of the technique are (1) use of glass standards made from geochemical standard rocks (JB-1 and BHVO-1) and (2) use of a small aluminum plate on which samples and standards are precisely mounted for gamma-ray counting. Twelve silicate spherules obtained from dredged deep-sea sediments were analyzed for trace and major elements by applying the above method of neutron activation and electron microprobe analysis. The results show that most of the silicate sphemles analyzed have marine origin except for a 0.7mm glassy spherule of meteoritic origin reported in the previous paper (NAGASAWA et al., 1979).View full abstractDownload PDF (2191K) -
Ken'ichi Nogami, Tadashi Shimamura, Yuji Tazawa, Kazuo Yamakoshi1980 Volume 14 Issue 1 Pages 11-18
Published: 1980
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSFor the purpose of deciding the extraterrestrial origin of the magnetic spherules found in deep sea sediments, the siderophile elements Co, Ni, Ir and/or Au etc., were measured by instrumental neutron activation analysis. Spherules were collected from red clay samples which were dredged from Mid Pacific Ocean. Only spherules which had smooth surfaces and relatively high specific gravities were chosen for analysis. Existence of Co, Ni and It in most spherules suggests the possibility of an extraterrestrial origin for these spherules. It is not clear whether these spherules are droplets ablated from iron meteorites entering into the Earth's atmosphere or they are cosmic iron grains themselves. X-ray diffraction analysis suggested that these spherules are the products of rapid cooling materials.View full abstractDownload PDF (1665K) -
Shizuo Tsunogai, Masatoshi Yamada1980 Volume 14 Issue 1 Pages 19-26
Published: 1980
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSA sediment core obtained from the northeastern Philippine Sea Basin was analyzed for 232Th, 230Th, 226Ra and 210Pb. Three sheets of Ferro-manganese oxide in a matrix of red clay were included in the 73 m core. Although the concentration of 232Th of land origin is normal as compared with that of the usual red clay or of the sediment obtained at the neighboring station, the concentration of radiogenic 230Th is extremely low and does not decrease with increasing depth. The radioactivity of rather soluble 226Ra at the station is not less than that of 230Th in the surface sediment, showing a tendency different from that observed in usual cores. Some enrichment in the comparatively short-lived 210Pb activity relative to 226Ra activity was found in the top sediment and in the first ferro-manganese sheet at the station. If the excess 210Pb in the ferro-manganese sheet is not due to contamination of the surface sediment, lead should migrate through the sheet. These facts suggest that the core has not been accumulating during the past few hundred thousand years or more.View full abstractDownload PDF (1704K) -
J. W. Smith, K. W. Gould1980 Volume 14 Issue 1 Pages 27-32
Published: 1980
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSThe occurrence of instantaneous outbursting in the Bulli coal seam at the West Cliff Colliery, Appin, NSW can be correlated directly with an increase in concentration (0.5 to 75%) and a related decrease in the 13C content (δ13C +16 to -8‰ PDB) of the CO2 in the seam gas. Two sources of CO2 are required. The greater incidence of outbursting in CO2-rich zones is explained by the conversion to bicarbonate of cleat and fracture filling calcite deep within the coal and the transport of this bicarbonate in water to mine openings. The weakening of the resistance of the coal to shear by this removal of carbonate is an additional factor to be considered in assessing outbursting situations.View full abstractDownload PDF (1416K) -
Lawrence M. Barron1980 Volume 14 Issue 1 Pages 33-40
Published: 1980
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSA scheme for converting the output from a CIPW norm to compositions of coexisting feldspars is described. The scheme, empirically calibrated on suites of plutonic rocks, has three modes of output: -coexisting alkali feldspar and plagioclase -two coexisting alkali feldspars -only one feldspar The scheme has been tested on a gabbro-diorite-tonalite-trondhjemite suite (Finland), a granodiorite suite (Sierra Nevada) and an adamellite-granite suite (N.S.W.). Compositions and relative amounts of the various feldspars are calculated from the norm and they show good agreement with modal ratios and feldspar compositions from the rocks, except when modal biotite exceeds 18%. The scheme is less successful when applied to rocks from an alkaline complex (Monchique) probably because of high sodium partitioning into alkali amphiboles and pyroxenes. While the scheme yields useful information about volcanics it cannot mimic the phenocrystic character of porphyritic rocks as is indicated on some basalts and talc-alkaline volcanics (Utah).View full abstractDownload PDF (1566K) -
Jun-ichi Matsuda1980 Volume 14 Issue 1 Pages 41-46
Published: 1980
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSThe initial (87Sr/86Sr) ratios of alkali rocks from the Line chain (Line Islands) in the Pacific Ocean are variable, but may be divided into three groups; (1) The low (87Sr/86Sr) ratios of the main chain (∼0.7031). (2) The high (87Sr/86Sr) ratios for the site located off the main chain (∼0.7043). (3) The low (87Sr/86Sr) ratios of the Line Cross chain (∼0.7034), which is not clearly discriminated from the main chain. The low (87Sr/86Sr) ratios of alkali basalts seem to suggest that the magma sources of hot spots are in the ‘depleted’ upper portion of the mantle, in spite of the fact that the hot spots should be situated in the deep position of the mantle.View full abstractDownload PDF (1337K) -
Ricardo M. Pytkowicz1980 Volume 14 Issue 1 Pages 47-50
Published: 1980
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSTwo topics are examined in this work; the similar relative compositions of the sedimentary lithosphere and of crustal igneous rocks and the problem of the excess crustal calcium. The latter is shown to be due primarily to the biologically mediated conversion of plagioclase feldspars which has been accelerated since the Cambrian and to the trapping of the resultant CaCO3 on continental shelves.View full abstractDownload PDF (820K) -
Surinder Singh, H. S. Virk1980 Volume 14 Issue 1 Pages 51-55
Published: 1980
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSFrom the fission track age determination of garnet occurring in copper ore deposits of Khetri copper belt, Rajasthan, it has been possible to reveal the metamorphism of copper ore formations of the area. The fission track age of 831 ± 132m.y. for garnet suggests that the copper ore formations in the region were subjected to a metamorphic episode which coincides with the Delhi Cycle.View full abstractDownload PDF (964K) -
Akimasa Masuda, Yoshiteru Dohmoto1980 Volume 14 Issue 1 Pages 57-61
Published: 1980
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSWhen 193Nd/144Nd ratios of oceanic basalts are plotted against the observed Sm/Nd ratios, the points appear widely scattered. But when a reduction procedure is applied on the basis of a model for development of oceanic basalt REE patterns with DSm/DNd = 1.32, one can obtain a linear correlation between 143Nd/144Nd and 147Sm/144Nd, with two subparallel alignments. Ages (∼730 and 1600-1900Myr) deduced therefrom can be consistent with those presented for development of continental crust.View full abstractDownload PDF (1202K) -
1980 Volume 14 Issue 1 Pages e1
Published: 1980
Released on J-STAGE: February 06, 2009
JOURNAL FREE ACCESSDownload PDF (45K)
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