石浦-德邱間에 分布하는 所謂 洪濟寺花崗岩의 地質年代와 生成過程에 對한 硏究

• 영문명: Geochronology and Petrogenetic processes of the so-called Hongjesa granite in the Seogpo-Deogku Area
• 발행기관: 대한자원환경지질학회
• 저자명: Yong Jun Kim(金勇俊) Dai Sung Lee(李大聲)
• 간행물 정보: 『자원환경지질』16권 3호, 163~221쪽, 전체 59쪽
• 주제분류: 자연과학 > 지질학
• 파일형태: PDF
• 발행일자: 1983.09.30

영문 초록

Main aspects of this study are to clarify geochronology and petrogenetic processes of the so-called Hongjesa granite, which is a member of various intrusive rocks exposed in the northeastern part of the Ryongnam Massif, one of the Precambrian basements of South Korea. In this study, the Hongjesa grainte is divided into four rock units based on the geologic age, mineralogical and chemical constituents, and texture: the Precambrian Hongjesa granite gneiss (Hongjesa granite Proper) and leucogranite gneiss, the Paleozoic gnessic two mica granite, and the Jurassic muscovite granite. The Hongjesa granite gneiss is identified by its grayish color, slight foliation, and porphyroblastic texture. The leucogranite gneiss is distinct by its light gray color, sand medium to coarse grained texture. The gneissic two mica granite is distinguished from others by its strong foliation, containing gray-colored feldspar phenocrysts with biotite and muscovite in varying amounts. The muscovite granite occurs as a small stock containing feldspar phenocrysts along margin of the stock. These granitic rocks vary widely in composition, reflecting the facts that they partly include highly metamorphosed xenolith and schlierens as relics of magmatic and anatectic processes. In particular, grayish porphyroblasts of microcline perthite is characteristic of the Hongjesa granite gneiss, whereas epidote and garnet occur in both the Hongjesa granite gneiss and leucogranite gneiss. These minerals are considered to be formed by potassic metasomatism and contamination of highly metamorphosed rocks deeply buried under the level of the Hongjesa granite emplacement. The individual synchronous granitic rocks plotted on Harker diagram show mostly similar trends to the Daly’s values. The plots of the Hongjesa granite gneiss and gneissic two mica granite concentrate near the end part of the calc-alkalic rock series on the AMF diagrams, whereas those of the leucogranite gneiss and muscovite granite indicate the trend of the Skaergaard pluton. These granitic rocks plotted on a Q-Ab-Or diagram (petrogeny’s residua system) fall well outside the trough of the system. This can be attributed to the potassic matasomatism of these rocks. On the ACF diagram, these rocks appear to be dominantly I-type prevailing over S-type. The K-Ar ages, obtained from a total of 7 samples of the leucogranite gneiss, gneissic two mica granite, muscovite granite, porphyritic alkali granite, and rhyolitic rock, in addition to the Rb/Sr ages of the Hongjesa granite gneiss by previous workers, permit the rock units to be arranged in the following chronological order: The middle Proterozoic Hongjesa granite gneiss (1714-1825 m.y.), the upper proterozoic leucogranite gneiss (875-880 m. y.), the middle Paleozoic gneissic two mica granite (384 m. y.) the upper Jurassic muscovite granite (147 m. y.), the Eocene alkali granite (52 m. y.), and the Eocene rhyolitic rock (45 m. y.). From the facts and data mentioned above, it is concluded that the so-called Hongjesa granite is not a single granitic mass but is further subdivided into the four rock units. The Hongjesa granite gneis, leucogranite gneiss, and gneissic two mica granite are postulated to be either magmatic or parautochtonous, intrusive, and the later muscovite granite is to be magmatic in origion.

목차

ABSTRACT

1. 序言

2. 謝辭

3. 廣城地質

4. 石浦-第二蓮花鑛山 地域과 蔚珍鑛山 附近의 火成岩類

5. 所謂 洪濟寺花崗岩類의 鑛物組成과 化學成分

6. 構造運動 및 變成作用과 所謂 洪濟寺花崗岩類와의 關係

7. 火成岩類의 地質年代

8. 深成 火成岩類의 生成過程

9. 地質構造와 地史

10. 結論

參考文獻