All issues
Volume 15, Issue 1
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
-
Kimitaka Kawamura, Ryoshi Ishiwatari1981 Volume 15 Issue 1 Pages 1-8
Published: 1981
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSHeating experiments of a lacustrine sediment were conducted at 120, 150 and 198°C for 48hrs each for better understanding the behavior of fatty acids (FA's) in a sediment during early diagenesis. Two forms of FA's, “unbound FA's” extracted with organic solvents and “bound FA's” recovered by saponification of the pre-extracted sediments, were determined on unheated and heated sediments, with the following results: (1) The concentration of total (unbound + bound) lower molecular weight fatty acids (LFA's: C12 to C19) increased from 81μg/g dry sediment (unheated) to 95μg/g dry sediment at 198°C. The concentration of total higher molecular weight fatty acids (HFA's: C20 to C30) also increased from 36μg/g dry sediment (unheated) to 51μg/g dry sediment at 198°C. This fact suggests the presence of “tightly bound form” of FA's, i.e. FA's which can be recovered only after the thermal treatments of sediments. (2) Bound LFA's decreased rapidly on heating while unbound LFA's increased gradually. On the other hand, bound HFA's first decreased at 120°C and then increased at higher temperatures. Unbound HFA's show a similar changing pattern. The difference in the behavior on heating between bound LFA's and bound HFA's was interpreted in terms of their existence state which may be closely related with their origins.View full abstractDownload PDF (2178K) -
P. Hahn-Weinheimer, A. Hirner1981 Volume 15 Issue 1 Pages 9-15
Published: 1981
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSThe stable isotopic composition of carbon in graphites from various localities is in general informative for the genesis of graphite. A differentiation between the origin from carbonates, igneous or biogenic carbon can be established by stable carbon isotope determinations in many cases. On the other hand, it is indispensable to know the influence of various events causing shift of the isotopic ratio. After discussion of origin and stable isotopic composition of graphites, five typical case studies are presented.View full abstractDownload PDF (1950K) -
Hideo Tsunakawa, Masahisa Yanagisawa1981 Volume 15 Issue 1 Pages 17-23
Published: 1981
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSSome granitic rocks and basaltic dikes of the Minnesota River Valley were dated by Rb-Sr and 40Ar-39Ar methods. The obtained Rb-Sr mineral isochron ages are as follows: Morton gneiss 2.55 ± 0.06 (1σ)b.y. and its biotite ages 2.38b.y., Sacred Heart granite 2.37 ± 0.05 (1σ)b.y., Montevideo gneiss 1.82 ± 0.09 (1σ)b.y. Each age may be corresponding to the respective geological event. Whole rock samples of the Morton and Montevideo gneisses, however, do not define a Rb-Sr isochron age. From 40Ar-39Ar dating results, a mild geological disturbance which might have occurred about 1.0b.y. ago was inferred. These results imply a complex history of the gneisses and a metamorphism in this region.View full abstractDownload PDF (1874K) -
A. Thus, G. De Roy, E. F. Vansant, G. P. Glasby, T. Thijssen1981 Volume 15 Issue 1 Pages 25-37
Published: 1981
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSMössbauer spectra have been obtained for a limited number of manganese nodules and associated sediments from five areas in the equatorial Pacific high productivity zone and in the S.W. Pacific. The results offer strong evidence that the form of iron in deep-sea manganese nodules is identical and independent of the environment of deposition. Iron occurs in deep-sea nodules as a mixture of α-FeOOH and β-, γ-FeOOH or poorly crystallised Fe oxides. In the associated sediments, iron in the equatorial Pacific sediments appears to be entirely in the ferric state whereas in S.W. Pacific sediments about 15% of the iron is present in the ferrous form. It has not proved possible, using Mössbauer spectra alone, to establish unambiguously whether the iron in the sediments occurs as iron oxidehydroxides or as clay minerals. The data, however, do place boundary conditions on the formation of iron in these sediments.View full abstractDownload PDF (3349K) -
Shigeru Ohde, Yasushi Kitano1981 Volume 15 Issue 1 Pages 39-45
Published: 1981
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSIn order to elucidate the transformation of natural magnesian calcite to a more stable carbonate mineral, the present authors have studied the influence of magnesium ions in solution on the transformation through the dissolution experiment in the laboratory. Magnesian calcite in biological systems such as calcareous algae transforms into low-magnesian calcite in solutions containing no magnesium ions. In solution with magnesium ions, however, the transformation of magnesian calcite is inhibited and its magnesium carbonate content is increased owing to the dissolution of calcium carbonate portion. These results are useful or understanding the mineralogical change of carbonates in aquatic environment.View full abstractDownload PDF (1708K) -
Gy. Jakli, W. Alexander Van Hook1981 Volume 15 Issue 1 Pages 47-50
Published: 1981
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSAnalysis of the data of KAKIUCHI and MATASUO (1979) and other work on H/D fractionation factors for water(liq)↔water(vapor) verifies earlier observations of the ratio, lnRDOD/lnRHOD = γ = 1.91 ± 0.02, (lnRDOD = ln(PHOH/PDOD), lnRHOD = ln(PHOH/PHOD)). Analysis of KM's data on 18O/ 16O fractionation according to the method of JANCSO and VAN HOOK (1978a) shows good agreement between fractionation factors and measurements of vapor pressures of separated isotopes. A significant volume dependence for the high frequency OH stetching motions in water is verified.View full abstractDownload PDF (1200K)
- |<
- <
- 1
- >
- >|