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Volume 25 (1991)
- Issue 2 Pages 69-
- Issue 1 Pages 1-
Volume 25, Issue 2
Displaying 1-6 of 6 articles from this issue
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Special Issues: Geochemical map and its significance
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Masami ICHIKUNI1992 Volume 25 Issue 2 Pages 69-71
Published: April 27, 1992
Released on J-STAGE: December 08, 2016
JOURNAL FREE ACCESSGeochemical map represents the concentration pattern for different elements in the surface media, for example, rocks and soils. Stream sediments are considered to be complementary to soils. The sediments are a composite sample of weathered material upstream from the sampling site. Sampling density varies from 1 sample per 1km2 (stream sediment in Japan) to 1 per 320km2 (till in Finland). A wider spaced sampling has been accepted in some cases. Geochemical map is expected to provide useful information on mineral exploration, environmental pollution as well as agricultural applications.View full abstractDownload PDF (351K) -
Shiro ITOH1992 Volume 25 Issue 2 Pages 73-80
Published: April 27, 1992
Released on J-STAGE: December 08, 2016
JOURNAL FREE ACCESSSeveral countries of Europe and United State of America have issued the regional geochemical atlas of their full territory or a part of the territory. Progress in making the atlas is reviewed. It is noticed that somewhat different methods were employed according to the topography, climate and the extent of land to be surveyed. Whatever the methods were different the usefulness of the atlas has been cleared.View full abstractDownload PDF (858K) -
Hikari KAMIOKA, Tsuyoshi TANAKA, Shiro ITOH, Noboru IMAI1992 Volume 25 Issue 2 Pages 81-99
Published: April 27, 1992
Released on J-STAGE: December 08, 2016
JOURNAL FREE ACCESSThe geochemical map shows regional distribution patterns of elements and provides basic information on land. The Geological Survey of Japan has recently completed geochemical maps for the area of 4000km2 in the northeastern Kanto District. Stream sediments chosen as sample, may represent chemical compositions of their upstream areas. They were collected at every exit of drainage basins to cover the wide area efficiently. About 4000 samples were collected from the mapped area and were analyzed by ICP-AES and INAA for 53 elements in total. An engineering work station was used for the data processing. The data base of samples was constructed for the analytical results etc. The upstream area of each sample was input as a polygon using a digitizer. The polygon date were then combined with the chemical data and converted into mesh data. They were processed further to give contour map etc. Distribution patterns of elements shown on geochemical maps are closly related with the geology of the mapped area clearly. For example, the regions rich in REE, Hf, U, Th etc. coincide with the distribution of granitic rocks. Some Kieslager and vein type ore deposits are also detected as distinct chemical haloes of Cu, W, Pb, F and so on. Furthermore the distribution of several elements such as P and heavy metals are found to be affected by human activities.View full abstractDownload PDF (3251K) -
Makoto SHIIKAWA1992 Volume 25 Issue 2 Pages 101-125
Published: April 27, 1992
Released on J-STAGE: December 08, 2016
JOURNAL FREE ACCESSIn our country, a project of geochemical mapping was begun and carried out by the Committee for Applied Geochemical Research, attached to the Mining and Metallurgical Institute of Japan. The project was started in 1970 and continued until 1987. The first three years of the project were devoted to the basic research in elucidation and establishment of various methodologies, e.g., sampling, chemical analysis, data processing and visualization of processed data. In the remaining period of the project, the geochemical maps of different areas of Japan were constructed from the point of view of the exploration of mineral resources and geothermal energy. The maps were also useful for environmental studies. The geochemical map of the northern part of Akita Prefecture clearly shows a characteristic distribution of the Kuroko Deposits. Geochemical map of Inabe area, Mie Prefecture, provides information on the mineralization.View full abstractDownload PDF (2518K) -
Takashi NISHIYAMA1992 Volume 25 Issue 2 Pages 127-143
Published: April 27, 1992
Released on J-STAGE: December 08, 2016
JOURNAL FREE ACCESSGeochemical exploration has become increasingly attractive as a new technique of detecting ore concealed beneath a mantle of organic debris, soils, or barren rock, and of mapping geological structures. Geochemical prospecting for minerals is based on systematic measurements of chemical properties of naturally occurring materials such as water, stream or lake sediment, soil, vegetation, rock, and soil-gas. This technique is available for use in both reconnaissance surveys and detailed ones. Some element or a group of elememts in a low concentration is commonly involved in the technique, and sometimes stable isotopes or fluid inclusions are done. Some basic principles and concepts useful for the discovery of abnormal chemical patterns related with mineralization are discussed in this paper. In addition, new techniques using sulfide minerals and a soil-gas called "Fingerprint" are described.View full abstractDownload PDF (1361K) -
Yoji SEKI, Masatsugu OGASAWARA, Satoshi MURAO, Terumasa NAKAJIMA1992 Volume 25 Issue 2 Pages 145-160
Published: April 27, 1992
Released on J-STAGE: December 08, 2016
JOURNAL FREE ACCESSGeochemical exploration using bedrocks, stream waters and drill core samples has been carried out around the Takatori Sn-W vein type deposit, hosted in Mesozoic marine sediments. The halo of high anomalies of F, Li and Rb in bedrocks, ranging over 1.5×3.5km, was recognized around the Takatori deposit. These elements are thought to have been derived from granitic intrusions related to the Sn-W mineralization. The halo of high anomalies of F- in stream waters, which coincides with the halo on bedrocks, was also recognized. Leaching experiments using the bedrocks revealed that fluorite (CaF2) is a major source of disolved fluoride. Distribution profiles of elements that form geochemical halo in bedrock survey, which were drawn based on chemical analysis of drill cores, showed that the distribution patterns are closely related to aplite dykes intruding below the Sn-W deposit. The aplites as well as surrounding wall rocks suffered greisen alteration that is characterized by muscovite and fluorite. These facts indicate that the aplite dykes have genetically close relationship to the Sn-W mineralization. In addition to the aplite dykes, sheared zone below the aplite is thought to have had an important act as a pathway of ore fluid and a post-ore stage dislocation.View full abstractDownload PDF (1479K)
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