Abstract

The hydrothermal vein-type deposits which comprise the Sambong, Samsan, and Seongji mines are primarily copper deposits, but they have associated lead, zinc, and silver mineralization. The deposits occur within Upper Cretaceous volcanic rocks of the Gyeongsang basin of the southern Korean peninsula. Mineralization can be separated into three distinct stages (I, II, and III) which fill preexisting fault breccia zones. Each stage is terminated by an onset of fracturing and brecciation events. Fluid inclusion data suggest that stages I and II each evolved from initial high temperatures (near 350 degrees C) to later lower temperatures (near 200 degrees C). Each stage represents a separate mineralizing system which cooled and largely abated prior to the onset of the next stage. Fluid inclusion data from stage III, a postore, carbonate stage of mineralization, indicate a much cooler (190 degrees -120 degrees C), more dilute hydrothermal system which was probably the result of increasing influx of meteoric waters.Sulfur isotope and fluid inclusion evidence suggests that ore minerals were deposited at temperatures between 350 degrees and 250 degrees C from fluids with salinities ranging from 3 to 17 equivalent weight percent NaCl. Fluid inclusion evidence of boiling suggests pressures of less than 100 bars during portions of stage I and II mineralization. This pressure corresponds to depths at the time of mineralization between 500 and 1,250 m.Sulfur isotope compositions of sulfide minerals are consistent with an igneous source of sulfur with a delta 34 S (sub Sigma S) value near 4.0 per mil. Carbon and oxygen isotope compositions of carbonate-stage calcites suggest that meteoric water dominated the hydrothermal system at temperatures below 200 degrees C.The similarity of the features of the Sambong, Samsan, and Seongji mines to those of other copper-bearing hydrothermal deposits in Korea and elsewhere suggests a genetic tie between granitic magmatism and the development of the observed Cu-Pb-Zn-Ag mineralization and parageneses.

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