All issues
Volume 24 (1990)
- Issue 2 Pages 79-
- Issue 1 Pages 1-
Volume 24, Issue 1
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
Two Achievements for Geochemical Society Award
-
Tasuku AKAGI1990 Volume 24 Issue 1 Pages 1-11
Published: September 29, 1990
Released on J-STAGE: December 05, 2016
JOURNAL FREE ACCESSThis review deals with two separate geochemical subjects; diamonds and seawater. The work on diamonds concentrates on the cubic type, which are characterised by numerous micro-inclusions. Chemical studies have concluded that these inclusions are fluid rich in carbonates and incompatible elements. Other studies, including work by this author, have suggested that the fluid inclusions originate in the upper mantle. I present a model as to the genesis of both cubic and octahedral dianonds. Secondly, the behavior of trace elements in seawater is reviewed. Emphasis is placed upon estuarine and coastal waters where the behavior of the trace elements is the most complicated. In particular, understanding the reactions between suspended particles and dissolved species is important inorder to interpret the behavior of the trace elements. It was found that the adsorption of trace elements onto the surface of humicacid-coated particles takes place at an urbanized estuarine area. In the Seto Inland Sea the trace elements were much more conservative than in the estuarine area. Finally, some recent studies implying that seawater and diamond are linked through subducting ocean floor are reviewed.View full abstractDownload PDF (1141K) -
Keiji MISAWA1990 Volume 24 Issue 1 Pages 13-25
Published: September 29, 1990
Released on J-STAGE: December 05, 2016
JOURNAL FREE ACCESSTrace element abundances, especially rare earth elements (REE) abundances, have been used to constrain high temperature processes, such as gas/solid or liquid/solid fractionations and redox conditions in the early solar system. I review some recent studies on trace element abundances in chondrules from unequilibrated chondritic meteorites and briefly describe a procedure for direct-loading isotope dilution mass spectrometry. Recently obtained precise REE data on chondrules in carbonaceous chondritic meteorites (CV3 Allende and CO3 Felix) clearly demonstrate the existence of REE fractionation among chondrules, suggesting that very high temperature gas/solid (or gas /liquid) processing must have occurred prior to chondrule-formation melting event in the early solar nebula. Based on trace element abundances in chondrules, chemical features of precursor material and their melting processes are discussed.View full abstractDownload PDF (1286K)
Original Papers
-
Hiroshi OGAWA, Norio OGURA1990 Volume 24 Issue 1 Pages 27-41
Published: September 29, 1990
Released on J-STAGE: December 05, 2016
JOURNAL FREE ACCESSThe data of organic carbon observed in seawater of northwestern part of Tokyo Bay during 1980-1988 (except 1985) were arranged, and its source and behavior were discussed. It was observed that dissolved organic carbon (DOC) tended to decrease with increase of salinity in Tokyo Bay and riverine DOC was conservative in the Tamagawa Estuary. A linear relationship was observed between DOC and chlorophyll a (Chl. a) concentrations. The source of DOC in Tokyo Bay was estimated by multiple regression analysis between DOC, Chl. a and salinity. At St. 8 locating in estuary of the Arakawa River, the relative abundances of DOC derived from phytoplankton, terrestrial and oceanic waters were estimated to be 15%, 53% and 32%, respectively. On the other hand, at St. 35 near the center of the bay, DOC of respective origin was estimated to be 27%, 16% and 57%. Particulate organic carbon (POC) was positively correlated with Chi. a, but was not correlated with salinity. The source of POC in Tokyo Bay was estimated by the relationship between POC and Chi. a concentrations. The mean proportion of POC derived phytoplankton and non-phytoplankton origin was estimated to be 43% and 57% respectively at St. 8, and 69% and 31% at St. 35. The estimated origin of DOC and POC showed wide spatial and seasonal fluctuations.View full abstractDownload PDF (1211K) -
Hiroshi OGAWA, Norio OGURA1990 Volume 24 Issue 1 Pages 43-54
Published: September 29, 1990
Released on J-STAGE: December 05, 2016
JOURNAL FREE ACCESSThe data of chemical components observed in seawater of the northwestern part of Tokyo Bay during 1980-1988 (except 1985) were arranged and their fluctuations were discussed. In surface water at the station locating off the coast of Haneda, the conentrations of phosphate and total inorganic nitrogen showed seasonal fluctuations in the range of n.d.-8.7μg at-P•1-1 and 0.8-310 μg at-N•1-1. Those of dissolved organic carbon, particulate organic carbon and chlorophyll a varied also seasonally in the range of 0.9-5.8mg-C•1-1, 0.1-18mg-C•1-1 and 0.7-750μg•1-1, respectively. From the station locating in estuary of the Arakawa River to that near the center of the bay, the concentrations of inorganic nutrients decreased remarkably than organic components. The atomic ratio of N/P ranged from 17 to 380 in surface layer at the station off Haneda and showed a trend to increase gradually during 1980 to 1988, indicating that nitrogen excess in the nutritional condition was proceeding.View full abstractDownload PDF (1047K) -
Reiko SUZUKI, Yukiko SAKAI1990 Volume 24 Issue 1 Pages 55-64
Published: September 29, 1990
Released on J-STAGE: December 05, 2016
JOURNAL FREE ACCESSThe occurrence of Mn deposits formed from hot-spring waters has been described together with the chemical and mineralogical compositions of the deposits. Most of the deposits so far studied contain as much as 1 % of Ba. The deposites from Kita- Karuizawa, Shimabara and Akan hot-springs are mineralogically 10 Å manganite, as evidenced by the presence of considerable amounts of Ca and Mn (II). The deposit from Yunokoya is also high in these elements, but they are associated with calcite. The manganoan material in the deposit is X-ray amorphous. The Co content of the deposits probably depends on the Co content of the basement rock through which the hot-spring waters discharge: The Mn deposits from andesitic rock area are high in Co compared to those from granitic rock area. Differential thermal analysis and thermogravimetry of the Mn deposits have also been presented.View full abstractDownload PDF (751K) -
Yutaka YOSHIDA1990 Volume 24 Issue 1 Pages 65-77
Published: September 29, 1990
Released on J-STAGE: December 05, 2016
JOURNAL FREE ACCESSChemical and isotopic compositions of hot spring waters and well discharges of the Nigorikawa geothermal area were examined. On the basis of SO4/Cl ratios, geothermal waters can be classified into four groups from high to low value as follows; (1)Hot springs located at outside the Basin, (2)Hot water discharged from wells drilled into the pre-Tertiary formation of outside the Nigorikawa caldera, (3)Hot water discharged from wells drilled into a fracture zone of caldera wall, (4)Hot springs in the Nigorikawa Basin. Such a classification coincides with the geological conditions of reservoir. Although four types of hot water exist, almost all SO4 ion are supplied from anhydrite contained in formations, and the SO4 concentration is controlled by an anhydrite solubility. Anhydrite, Cl and Br are derived from sea water. Geothermal water is basically mixture of sea water and meteoric water. But, hot waters show very high enrichment of 18O (δ18O= 23‰ at δD=0‰ extrapolation), and the relation between Cl and δD of hot waters are different from that of simple mixture of surface water and sea water. It suggests that seawater is altered in the penetrating process.View full abstractDownload PDF (1064K)
- |<
- <
- 1
- >
- >|