Econ. Environ. Geol. 2001; 34(6): 555-571

Published online December 31, 2001

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

The Geodynamic Evolution of the Chugaryeong Fault Valley in a View Point of Paleomagnetism

Youn Soo Lee1*, Kyung Duck Min2 and Jae Ha Hwang1

1Korea Institute of Geoscience and Mineral Resources, Daejon 305-350, Korea
2Yonsei University, Department of Earth System Sciences, Seoul 120-749, Korea

Correspondence to :

Youn Soo Lee

leeys@ysgeo.yonsei.ac.kr

Received: August 30, 2001; Accepted: December 19, 2001

Abstract

The dynamic evolution of the Chugaryeong fault valley is studied by paleomagnetic works on 163 samples at 16 sites from Late Cretaceous and Quaternary volcanic rocks in the valley. Conglomerate test and stepwised thermal/alternating field demagnetization indicate that all the characteristic directions are of primary origin. Paleomagnetic pole position (216.8oE/71.6oN; dp=7.1o, dm=10.0o) for the upper part of the Jijangbong Volcanic Complex is indistinguishable from the coeval reference pole position from the Gyeongsang Basin, which further substanciates the reliability of the paleomagnetic data. This indicates the study area has not undergone any tectonic rotation since Late Cretaceous by any significant reactivation of the Chugaryeong fault valley. The Quaternary pole position (134.2oE/86.5oN; A95=7.1o) from the Jeongog Basalt reflects the present geocentric axial dipole field for the area, supporting the above conclusion. Unlike the upper part, paleomagnetic directions of the lower part of the Jijangbong Volcanic Complex show random
distrinution between sites. We interpret that the early stage of the volcanic activity was created by sinistral strikeslip motion of the Chugaryeong fault during early Late Cretaceous. The creation and evolution of the Chugaryeong fault valley emphasize the significance of the kinematic FR (folding ruler) model in East Asia.

Keywords chugaryeong, paleomagnetism, strike-slip fault, rejuvenation

Article

Econ. Environ. Geol. 2001; 34(6): 555-571

Published online December 31, 2001

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

The Geodynamic Evolution of the Chugaryeong Fault Valley in a View Point of Paleomagnetism

Youn Soo Lee1*, Kyung Duck Min2 and Jae Ha Hwang1

1Korea Institute of Geoscience and Mineral Resources, Daejon 305-350, Korea
2Yonsei University, Department of Earth System Sciences, Seoul 120-749, Korea

Correspondence to:

Youn Soo Lee

leeys@ysgeo.yonsei.ac.kr

Received: August 30, 2001; Accepted: December 19, 2001

Abstract

The dynamic evolution of the Chugaryeong fault valley is studied by paleomagnetic works on 163 samples at 16 sites from Late Cretaceous and Quaternary volcanic rocks in the valley. Conglomerate test and stepwised thermal/alternating field demagnetization indicate that all the characteristic directions are of primary origin. Paleomagnetic pole position (216.8oE/71.6oN; dp=7.1o, dm=10.0o) for the upper part of the Jijangbong Volcanic Complex is indistinguishable from the coeval reference pole position from the Gyeongsang Basin, which further substanciates the reliability of the paleomagnetic data. This indicates the study area has not undergone any tectonic rotation since Late Cretaceous by any significant reactivation of the Chugaryeong fault valley. The Quaternary pole position (134.2oE/86.5oN; A95=7.1o) from the Jeongog Basalt reflects the present geocentric axial dipole field for the area, supporting the above conclusion. Unlike the upper part, paleomagnetic directions of the lower part of the Jijangbong Volcanic Complex show random
distrinution between sites. We interpret that the early stage of the volcanic activity was created by sinistral strikeslip motion of the Chugaryeong fault during early Late Cretaceous. The creation and evolution of the Chugaryeong fault valley emphasize the significance of the kinematic FR (folding ruler) model in East Asia.

Keywords chugaryeong, paleomagnetism, strike-slip fault, rejuvenation

    KSEEG
    Jun 30, 2024 Vol.57 No.3, pp. 281~352

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