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Sturctural Geometry of the Pyeongchang-Jeongseon Area of the Northwestern Taebaeksan Zone, Okcheon Belt
옥천대 북서부 태백산지역 평창-정선일대 지질구조의 기하학적 형태 해석
Econ. Environ. Geol. 2019 Dec;52(6):541-54
Published online December 31, 2019;  https://doi.org/10.9719/EEG.2019.52.6.541
Copyright © 2019 the Korean society of economic and environmental gelology.

Yirang Jang1* and Hee Jun Cheong2
장이랑1* · 정희준2

1Geology Division, Korea Institute of Geosciences and Mineral Resources, Daejeon 34132, Republic of Korea
2Department of Earth system sciences, Yonsei University, Seoul 03722, Republic of Korea
1한국지질자원연구원 국토지질연구본부, 2연세대학교 지구시스템과학과
Received December 21, 2019; Revised December 24, 2019; Accepted December 25, 2019.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
 Abstract
The Taebaeksan Zone of the Okcheon Belt is a prominent fold-thrust belt, preserving evidence for overlapped polyphase and diachronous orogenic events during crustal evolution of the Korean Peninsula. The Pyeongchang-Jeongseon area of the northwestern Taebaeksan Zone is fault-bounded on the western Jucheon and southern Yeongwol areas, showing lateral variations in stratigraphy and structural geometries. For better understanding these geological characteristics of the northwestern Taebaeksan Zone, we have studied the structural geometry of the Pyeongchang-Jeongseon area. For this, we have firstly carried out the SHRIMP U-Pb age analysis of the ageunknown sedimentary rock to clarify stratigraphy for structural interpretation. The results show the late Carboniferous to middle Permian dates, indicating that it is correlated to the Upper Paleozoic Pyeongan Supergroup. In addition to this, we interpreted the geometric relationships between structural elements from the detailed field investigation of the study area. The major structure of the northwestern Taebaeksan Zone is the regional-scale Jeongseon Great syncline, having NE-trending hinge with second-order folds such as the Jidongri and Imhari anticlines and the Nambyeongsan syncline. Based on the stereographic and down-plunge projections of the structureal elements, the structural geometry of the Jeongseon Great syncline can be interpreted as a synformal culmination, plunging slightly to the south at its southern area, and north at the northern area. The different map patterns of the northern and southern parts of the study area should be resulted in different erosion levels caused by the plunging hinges. Considering the Jeongseon Great syncline is the major structure that constrains the distribution of the Paleozoic strata of the Pyeongchang and Jeongseon areas, the symmetric repetition of the lower Paleozoic Joseon Supergroup in both limbs should be re-examined by structural mapping of the Hangmae and Hoedongri formations in the Pyeongchang and Jeongseon areas.
Keywords : structural geometry, Jeongseon Great syncline, Hangmae Formation, Hoedongri Formation, Pyeongchang area

 

December 2019, 52 (6)