• Economic and Environmental Geology
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• v.11 no.4
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• pp.127-141
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• 1978

The major structures characteristic of the Taebaegsan sedimentary basin were regionally analyzed with special reference to its southeastern extension to the Yeonhwa-Ulchin district of economic interest in zinc-lead mineralization. The basin geometry, basement setting, sedimentary components, and the characteristics of deformation and igneous activity of the Taebaegsan basin differ basically from those of the adjacent mobile belt of the Ogcheon geosyncline, although the latter affected the basin's western side considerably. The subrectangular shape of the Taebaegsan basin reflects the checkered pattern of basement-block arrangement, and the carbonate-dominated lithologic components of the basin-fill indicate a cratonic depositional setting, which is comparable to some of the North American mid-continental craton. The Taebaegsan basin, however, has somewhat been less stable than the North American megacraton that is reflected in the former's thicker sedimentary fill and steeper faults of later deformation, showing a tendency to increase in thickness close to the basement-block boundaries, which may indicate contacts of possibly detached cratonic blocks of Precambrian age; these weak zones of block boundaries have been the loci of repeated sedimentation, deformation and related igneous intrusions. A series of downthrown or uplifted tilted blocks, in which the Cambro-Ordovician sedimentary wedges and the late Cretaceous to early Tertiary igneous intrusives are involved, occurs intermittently across the Yeonhwa-Ulchin district in a noticeable pattern of en echelon type. These sedimentary wedges are correlated to the Cambro-Ordovician section of the Hambaeg syncline to the west in stratigraphy and lithology, and are considered to have resulted from the northeastern and/or northwestern cross-faulting of the pre-existing syncline belt of easterly trend, extended from the main portion of the Hambaeg syncline. These structural junctions (or intersections) of the earlier syncline belt and the later cross-faults have been acted as a guide to ascending igneous materials and hydrothermal ore-forming fluids to form a zone of zinc-lead skarn deposits across the Yeonhwa-Ulchin district showing a stepwise recurrence of these deposits toward the east.