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Econ. Environ. Geol. 2024; 57(1): 73-81

Published online February 29, 2024

https://doi.org/10.9719/EEG.2024.57.1.73

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Displacement of Dongducheon and Wangsukcheon Fault Observed by Gravity Field Interpretation

Sungchan Choi1, Sung-Wook Kim1,*, Eun-Kyeong Choi1, Younghong Shin2

1Geo-information Institute, GI Co. Ltd., Busan, 47598, Korea
2Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Republic of Korea

Correspondence to : *suwokim@chol.com

Received: December 21, 2023; Revised: February 22, 2024; Accepted: February 23, 2024

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 original work is properly cited.

Abstract

To estimate the tectonic displacement of the Chugaryeong Fault System (CFS), gravity surveys were conducted along the Dongducheon fault (DF) and the Wangsukcheon fault (WF). A total of 1,100 stations for the DF and WF regions have been added to the current gravity database. The results of the gravity interpretation indicate that (1) the dextral displacement of the DF is about 3,000 m, similar to the tectonic displacement (2,900-3,100 m) shown in the geological map. (2) The dextral displacement of the WF is about 3,200 m. (3) Taken together, the tectonic displacement of the CFS is estimated to be about 3,000 m on average. To investigate more accurate tectonic displacement of the CFS, further gravity surveys is planned for the Pocheon fault, Gyeonggang fault, and Inje fault.

Keywords gravity interpretation, tectonic displacement, Chugaryeong Fault System, Dongducheon fault, Wangsukcheon fault

중력장 해석으로 관측된 동두천 및 왕숙천 단층의 변위

최승찬1 · 김성욱1,* · 최은경1 · 신영홍2

1지아이 지반정보연구소
2한국지질자원연구원

요 약

추가령 단층대의 지구조적인 이동을 확인하기 위해 경기 북부와 양주 및 서울 지역을 통과하는 동두천 단층과 서울 동쪽 지역에서 북동-남서 방향으로 발달한 왕숙천 단층을 따라서 중력장을 측정하였으며 두 지역에서 약 1,100여 점의 중력 자료를 획득하였다. 두 단층대의 중력장 해석 결과는 다음과 같다. (1) 동두천 단층이 우향으로 약 3,000 m 정도 이동하였으며 이는 지질도에서 관찰되는 동두천 단층 일원 암석의 우향 이동 규모(2,900-3,100 m)와 일치한다. (2) 왕숙천 단층의 우향 변위는 약 3,200 m이다. (3) 이를 종합하면, 추가령 단층대의 우향 변위는 평균 약 3,000 m 정도로 판단된다. 추가령 단층대의 변위를 좀 더 정확히 확인하기 위해서, 포천 단층, 경강 단층 및 인제 단층의 변위 정도를 파악하기 위한 중력 측정과 해석이 추가로 필요하다.

주요어 중력장 해석, 지구조적 변위, 추가령 단층대, 동두천 단층, 왕숙천 단층

Article

Research Paper

Econ. Environ. Geol. 2024; 57(1): 73-81

Published online February 29, 2024 https://doi.org/10.9719/EEG.2024.57.1.73

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Displacement of Dongducheon and Wangsukcheon Fault Observed by Gravity Field Interpretation

Sungchan Choi1, Sung-Wook Kim1,*, Eun-Kyeong Choi1, Younghong Shin2

1Geo-information Institute, GI Co. Ltd., Busan, 47598, Korea
2Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Republic of Korea

Correspondence to:*suwokim@chol.com

Received: December 21, 2023; Revised: February 22, 2024; Accepted: February 23, 2024

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 original work is properly cited.

Abstract

To estimate the tectonic displacement of the Chugaryeong Fault System (CFS), gravity surveys were conducted along the Dongducheon fault (DF) and the Wangsukcheon fault (WF). A total of 1,100 stations for the DF and WF regions have been added to the current gravity database. The results of the gravity interpretation indicate that (1) the dextral displacement of the DF is about 3,000 m, similar to the tectonic displacement (2,900-3,100 m) shown in the geological map. (2) The dextral displacement of the WF is about 3,200 m. (3) Taken together, the tectonic displacement of the CFS is estimated to be about 3,000 m on average. To investigate more accurate tectonic displacement of the CFS, further gravity surveys is planned for the Pocheon fault, Gyeonggang fault, and Inje fault.

Keywords gravity interpretation, tectonic displacement, Chugaryeong Fault System, Dongducheon fault, Wangsukcheon fault

중력장 해석으로 관측된 동두천 및 왕숙천 단층의 변위

최승찬1 · 김성욱1,* · 최은경1 · 신영홍2

1지아이 지반정보연구소
2한국지질자원연구원

Received: December 21, 2023; Revised: February 22, 2024; Accepted: February 23, 2024

요 약

추가령 단층대의 지구조적인 이동을 확인하기 위해 경기 북부와 양주 및 서울 지역을 통과하는 동두천 단층과 서울 동쪽 지역에서 북동-남서 방향으로 발달한 왕숙천 단층을 따라서 중력장을 측정하였으며 두 지역에서 약 1,100여 점의 중력 자료를 획득하였다. 두 단층대의 중력장 해석 결과는 다음과 같다. (1) 동두천 단층이 우향으로 약 3,000 m 정도 이동하였으며 이는 지질도에서 관찰되는 동두천 단층 일원 암석의 우향 이동 규모(2,900-3,100 m)와 일치한다. (2) 왕숙천 단층의 우향 변위는 약 3,200 m이다. (3) 이를 종합하면, 추가령 단층대의 우향 변위는 평균 약 3,000 m 정도로 판단된다. 추가령 단층대의 변위를 좀 더 정확히 확인하기 위해서, 포천 단층, 경강 단층 및 인제 단층의 변위 정도를 파악하기 위한 중력 측정과 해석이 추가로 필요하다.

주요어 중력장 해석, 지구조적 변위, 추가령 단층대, 동두천 단층, 왕숙천 단층

    Fig 1.

    Figure 1.(A) The Chugaryung Fault system (CFS) is located in the central part of the Korean Peninsula. The study area (red rectangle in Fig. 1B) is located in the Yangju area, north of Seoul, and is divided in half by the Dongducheon fault line(DF). Several faults belong to the CFS are numbered in Fig. 1B.
    Economic and Environmental Geology 2024; 57: 73-81https://doi.org/10.9719/EEG.2024.57.1.73

    Fig 2.

    Figure 2.Geological map (A) shows that the study area is divided in half by the NS-directing Dongducheon fault (DF), and its eastern part is characterized by a prominent ring-form structure composed of Garnet-bearing Biotite Granite (Jgbgr). Dextral displacement of the DF is approximated to be about 3,000 m by comparing locations of fault lines (e.g., Jeongok fault, Choseong Trust in B) and different rocks (e.g., Quartzite and Jgbgr in C) in western-and eastern DF. Bouguer anomaly map (D) shows NW-SE directing low anomalies, which are probably caused by NS striking dextral movement of the DF.
    Economic and Environmental Geology 2024; 57: 73-81https://doi.org/10.9719/EEG.2024.57.1.73

    Fig 3.

    Figure 3.The Bouguer anomaly map (A) and calculated Dip-curvature values (B) in the southern part of the study area show well a tectonic displacement of about 3,000 m, which is caused by dextral movement of the DF. C: The comparison of Bouguer anomaly field measured along the east-and the west side of the DF shows that the eastern side of the DF shifted 3,000 m south relative to the west. D: The comparison of Dip-Curvature value calculated along the east-and the west side of the DF shows also the tectonic displacement of about 3,000 m caused by the dextral movement of the DF.
    Economic and Environmental Geology 2024; 57: 73-81https://doi.org/10.9719/EEG.2024.57.1.73

    Fig 4.

    Figure 4.A shows that the NE-SW extending Wangsukcheon fault (WF) is located east of the Dongducheon fault (DF). The Bouguer anomaly map along the WF shown in B ranges from –8.0mGal to 1.0 mGal. The tectonic displacement of the WF is assumed to be about 3,200 m which is caused by the dextral movement of the WF (C).
    Economic and Environmental Geology 2024; 57: 73-81https://doi.org/10.9719/EEG.2024.57.1.73

    Table 1 . Densities of various rock types sampled from the middle part of the Korean Peninsula (Park et al., 2009).

    Rock TypeSampleDensity (g/cm3)
    RangeMeanSD
    Alluvium (Qa)< 2.30
    Basalt (Qba)32.62 ~ 2.832.720.10
    Seoul Biotite Granite (Jsgr)792.55 ~ 2.792.620.05
    Hornblende Granodiorite (Jhgd)82.55 ~ 2.762.660.07
    Garnet bearing Biotite Granite (Jgbgr)22.60 ~ 2.612.600.01
    Biotite Granite (Jbgr)1262.54 ~ 2.792.630.04
    Porphyritic Biotite Granite (Jpbgr)72.58 ~ 2.752.670.06
    Jeokseong Fm. (TRJjs)112.46 ~ 2.862.710.1
    Misan Fm. (DM, Sandstone)772.53 ~ 2.962.690.07
    Quartzite (Qz)292.53 ~ 2.972.630.09
    Gyeonggi Gneiss Complex (PEbgn)62.61 ~ 2.752.670.05

    KSEEG
    Apr 30, 2024 Vol.57 No.2, pp. 107~280

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