강원도 태백시 일대에 분포하는 풍촌층 돌로마이트의 성인 = The origin of the dolomite of the Pungchon Formation near Taebaeg City, Kangwondo, Korea

다국어 초록 (Multilingual Abstract)

The objective of this study is to investigate the origin of the dolomite in the Pungchon Formation of the Choseon Supergroup near Taebaeg City, Kangwondo, Korea. The Pungchon Formation is composed of limestone, dolomitic limestone, and dolomite with thin beds of flat pebble conglomerate (FPC) and mudrock. Texturally, the dolomite in the Pungchon Formation can be divided into four types; 1) coarse-sized, xenotopic dolomite in massive dolomite, 2) medium-siEed, idiotopic dolomite in flat pebble conglomerate, 3) xenotopic dolomite replacing ooids, algalnodules, and echinoderms, and 4) the dolomite in mottled fabric. The dolomite in mottled fabric can be subdivided into three types; a) coarse-sized, xenotopic saddle dolomite cement, b) medium-sized, idiotopic, cloudy-centered, clear-rimmed (CCCR) dolomite, and c) coarse-sized, idiotopic dolomite. The carbon isotopic composition of the Pungchon dolomite is in the range of $-2.8-1.4\%_{\circ}(PBD)$, suggesting that the carbon isotopic composition was buffered by the preexisting marine carbonates. Lighter oxygen isotopic values ($\delta^{18}O-15.7-8.7\%_{\circ}, PBD$) indicate that the Pungchon dolomite may have formed under high temperature in a burial diagenetic environment. The higher initial $^{87}Sr/^{86}Sr$ ratio of the Pungchon dolomite (0.7010-0.7161) than that of the coeval Cambrian seawater (0.7088-0.7092) indicates that dolomitizing fluids had been modified from the isotopic exchange with continental crust. Low Sr and Na contents(<200 ppm) of dolomite agree well with previously reported data for burial dolomite. Hifh Fe and Mn contents of the dolomite support the idea that the Pungchon dolomite may have formed in a deep burial diagenetic environment.