元素の地表分布パターンとその解析 : 北関東の地球化学図(<特集>地球化学図)

概要

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The 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 4000km^2 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.
日本地球化学会の論文
1992-04-27