paleomagnetism" /> Mutaek Lim" /> Mutaek Lim, Youn Soo Lee, Hee-Cheol Kang, Ju-Yong Kim and In-Hwa Park

" /> Mutaek Lim, Youn Soo Lee, Hee-Cheol Kang, Ju-Yong Kim and In-Hwa Park

. Econ. Environ. Geol. 2001;34:119-31. https://doi.org/">

Econ. Environ. Geol. 2001; 34(1): 119-131

Published online February 28, 2001

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Pleomagnetic Study on Cretaceous Rocks in Haenam Area

Mutaek Lim1*, Youn Soo Lee1, Hee-Cheol Kang2, Ju-Yong Kim1 and In-Hwa Park1

1Korea Institute of Geoscience and Mineral Resources, Daejeon, 305-350, Korea

2Department of Geology, Pusan National University, Pusan, 609-735, Korea

Correspondence to :

Mutaek Lim

limmt@rock25t.kigam.re.kr

Received: March 23, 1999; Accepted: February 9, 2001

Abstract

<p class="바탕글">A mean characteristic remanent magnetization was obtained for the first time in Korea from volcanic and pyroclastic sedimentary rocks distributed in Haenam Area, located in southwestern part of the Korean Peninsula. The age of the prevailing rocks in this area belongs mostly to Late Cretaceous, with a few exceptions of Early Cretaceous, mainly based on K/Ar whole rock age dating. Characteristic remanent magnetizations of these have both normal and reverse polarities with antipodal directions, which were interpreted to be the primary remanent magnetizations obtained by the ambinent Earth's magnetic field at the time of formation of the concerned rocks. The source magnetic minerals of the remanent magnetization has been identified as magnetite. The mean direction of characteristic remanent magnetization obtained from the Late Cretaceous rocks in this study is Dm/Im=21.4°/57.1°(?95= 13.4°, k=350.0). The paleomagnetic pole position calculated from this result for the Late Cretaceous, is 72.5°N/199.9°E (dp/dm=14.2°/19.5°), which matches well with those of 80 Ma (76.2°N/198.9°E) and 90 Ma (76.7°N/200.1°E) of the Eurasian Continent's APWP (Apparent Polar Wander Path). This result strongly indicates that the studied area, belonging to the Eurasian Continent, have suffered very little geotectonic movement after the Late Cretaceous. The deflection of declination of remanence from Early Cretaceous rocks in the study area may indicate that the micro-block was counterclockwisely rotated with vertical axis between the late of Early Cretaceous.

Keywords

paleomagnetism, Haenam, Cretaceous, characteristic remanent magnetization, volcanic rock

Article

Econ. Environ. Geol. 2001; 34(1): 119-131

Published online February 28, 2001

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Pleomagnetic Study on Cretaceous Rocks in Haenam Area

Mutaek Lim1*, Youn Soo Lee1, Hee-Cheol Kang2, Ju-Yong Kim1 and In-Hwa Park1

1Korea Institute of Geoscience and Mineral Resources, Daejeon, 305-350, Korea

2Department of Geology, Pusan National University, Pusan, 609-735, Korea

Correspondence to:

Mutaek Lim

limmt@rock25t.kigam.re.kr

Received: March 23, 1999; Accepted: February 9, 2001

Abstract

A mean characteristic remanent magnetization was obtained for the first time in Korea from volcanic and pyroclastic sedimentary rocks distributed in Haenam Area, located in southwestern part of the Korean Peninsula. The age of the prevailing rocks in this area belongs mostly to Late Cretaceous, with a few exceptions of Early Cretaceous, mainly based on K/Ar whole rock age dating. Characteristic remanent magnetizations of these have both normal and reverse polarities with antipodal directions, which were interpreted to be the primary remanent magnetizations obtained by the ambinent Earth's magnetic field at the time of formation of the concerned rocks. The source magnetic minerals of the remanent magnetization has been identified as magnetite. The mean direction of characteristic remanent magnetization obtained from the Late Cretaceous rocks in this study is Dm/Im=21.4°/57.1°(?95= 13.4°, k=350.0). The paleomagnetic pole position calculated from this result for the Late Cretaceous, is 72.5°N/199.9°E (dp/dm=14.2°/19.5°), which matches well with those of 80 Ma (76.2°N/198.9°E) and 90 Ma (76.7°N/200.1°E) of the Eurasian Continent's APWP (Apparent Polar Wander Path). This result strongly indicates that the studied area, belonging to the Eurasian Continent, have suffered very little geotectonic movement after the Late Cretaceous. The deflection of declination of remanence from Early Cretaceous rocks in the study area may indicate that the micro-block was counterclockwisely rotated with vertical axis between the late of Early Cretaceous.

Keywords

paleomagnetism, Haenam, Cretaceous, characteristic remanent magnetization, volcanic rock

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

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