朝日山地南西域と栗子地域の花崗岩類のRb-Sr含有量 : 棚倉構造線の北方延長(1)

概要

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Pre-Tertiary rocks are sporadically distributed as the basement complex of the Neogene and/or Paleogene formations in the "Green tuff region" of Northeast Honshu. These pre-Tertiary rocks are mainly composed of Cretaceous granitic rocks and area ssociated with some metamorphic rocks. The authors study magnetic susceptibility, facies change, Rubidium and Strontioum contents, and Rb^<87>/Sr^<86> ratio of the granitic rocks of the southwestern area of the Asahi Mountainland and the Kuriko area. As the result, the following facts are shown: (1) Granitic rocks of the both areas, except massive adamellite of the southwestern area of the Asahi Mountainland, belong to "ilmenite series" according to the classification by KANAYA and ISHIHARA (1973). (2) There is a strong correlation between facies change and inner structure within the granitic rocks which are not subjceted to secondary deformation or metamorphism. (3) Rb and Sr contents are different between the both areas. This difference may show that the source materials of the granitic rocks are different between the both areas. (4) Judging from the histogram of the Rb^<87>/Sr^<86> ratio, the granitic rocks of the Kuriko area and the older-type granitic rocks of the southwestern area of the Asahi Mountainland are similar to those of the Abukuma plutonic rocks, but the younger-type granitic rocks of the latter area are similar to those of the Ryoke plutonic belt.
日本地質学会の論文
1979-09-20