둔전금광산 북광상에서 산출되는 다상포유물내의 고상

Solid phases in polyphase inclusions from north ore deposits, Dunjeon gold mine

North ore deposits of the Dunjeon gold mine is disseminated-stockworks deposits emplaced in Ordovician Dongjeom quartzite. Six types of fluid inclusions are recongnized in the stage Ⅰ quartz. Among them polyphase inclusions(type-Ⅳ-A, B) are predominent in the lower part of stage Ⅰ quartz crystals whereas liquid and gas inclusions(type Ⅰ, Ⅱ) are abundant in the upper part of the same quartz crystals. Liquid CO₂-bearing inclusions(type Ⅲ-A, B) occur as pseudosecondary inclusions. Solid phases in polyphase inclusions are identified by using scanning electron microscopy combined with energy dispersive x-ray spectroscopy. The solid phases are as follows ; halite, sylvite, hydrophyllite, quartz, muscovite, calcite, ankerite, K-Mg-Fe-Al-Si mineral, Ca-Fe-Si mineral, Mg-AI-Si mineral, two kinds of Fe-mineral and Cu-Fe mineral. Results of freezing and heating experiments of fluid inclusions and identification of daughter minerals in polyphase inclusions in the stage Ⅰ quartz reveal that ore fluids were high saline system NaCl-KCl-CaCl₂-H₂O in the earier stage and then evolved to rather simple system NaCl-H₂O in the later stage, and temporally fluid mixing occured with system CO₂-H₂O Homogenization temperatures and salinity of fluid inclusions in the stage Ⅰ range from 290 to 454℃ and from 0.2 to 54.2 wt. % equivalent to NaCl.