先캠브리아紀 汾川 및 洪濟寺花崗岩類의 黑雲母에 對한 K-Ar 年代測定

• 영문명: K-Ar Ages on Biotites of the Proterozoic Buncheon and Hongjesa Granitic Rocks in the northeastern Part of the Sobaegsan Massif
• 발행기관: 대한자원환경지질학회
• 저자명: Young Kook Hong(洪永國) Tae Yun Choi(崔泰玧)
• 간행물 정보: 『자원환경지질』19권 2호, 147~151쪽, 전체 5쪽
• 주제분류: 자연과학 > 지질학
• 파일형태: PDF
• 발행일자: 1986.04.30

영문 초록

K-Ar ages on biotites have been determined from the Proterozoic Buncheon and Hongjesa granitic rocks in comparison with the Rb-Sr whole-rock ages to investigate the ages of metamorphic events. The Rb-Sr whole-rock ages determinations on the Buncheon and Hongjesa granitoid rocks were previously reported as 2,100Ma and 1,700Ma, respectively. K-Ar ages on biotites separated from the studied rock have revealed three different age groups such as 1) 1,200~1,300Ma, 2) 600~700Ma and 3) 300~400Ma. The Rb-Sr whole-rock ages for the granitic rocks represent the time of emplacement, whereas the K-Ar ages on biotites generally indicate the time of metamorphism or alteration. The large discordance in the two age systems may not be explained as indicating the cooling period of the granitic batholiths. The K-Ar ages on biotites from the granitoid rocks might not be simply interpreted as the age of the last phase of metamorphism, since the granitic rocks had been undergone multistages of amphibolite facies-metamorphism in the Precambrian period. During the multistages of intermediate grade metamorphism, ⁴⁰Ar-loss could be inevitably taken place as the metamorphic temperatures went up above the blocking temperature of biotite (300±50℃). The results of the K-Ar dating on biotites from this study are probably minimum ages or hydrothermal alteration ages.

목차

Abstract

序論

一般地質

K-Ar 黑雲母 年代測定

測定結果 및 解析

結言

參考文獻