北海道鴻之舞・沼の上地域における流紋岩中の元素分布について
1970 年 20 巻 100 号 p. 166-175
詳細
1970 年 20 巻 100 号 p. 166-175
The Konomai-Numanoue district, Hokkaido, Northern Japan, is one of the most important producers of gold and silver, in which so many hydrothermal deposits of Au-Ag bearing quartz veins in Neogenè age have been discovered and developed.
In order to obtain the basic data of primary dispersion of elements due to Au-Ag mineralization, and at the same time, to divide the huge body of the rhyolites in, upper parts of the Konomai formation into some units to understand the geologic structure of the rhyolite body, about 380 specimens of the rhyolites were collected and analyzed spectrochemically.
Following geochemical features of the rhyolites were deduced from the results of the investigation:
(1) The known Au-Ag deposits are surrounded by the halos in which some concentrations of Ag are recognized.
(2) The known Au-Ag deposits are situated in the Na-decreased zones which show the presence of hydrothermal alteration aureoles.
(3) The western part of the rhyolite body, can be devided into three units by the concentration characteristics of basic elements, such as Ni, Cr, Cu, etc.
(4) The known Au-Ag deposits except the Numanoue vein group are in the areas in which the basic elements are relatively concentrated.
