Original Article

Econ. Environ. Geol. 2015; 48(1): 41-49

Published online February 28, 2015

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Reactivated Timings of Inje Fault since the Mesozoic Era

Chuluunbaatar Khulganakhuu1, Yungoo Song1*, Donghoon Chung1, Changyun Park1, Sung-Ja Choi2, Il-Mo Kang2, and Keewook Yi3

1Department of Earth System Sciences, Yonsei University, Seoul 120-749, Korea
2Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Korea
3Korea Basic Science Institute, Ochang Center, Ochang 363-883, Korea

Correspondence to : yungoo@yonsei.ac.kr

Received: February 16, 2015; Revised: February 25, 2015; Accepted: February 25, 2015

Abstract

Recently developed illite-age-analysis(IAA) approach was applied to determine the fault-reactivated events for the Inje fault that cut through Precambrian biotite granitic gneiss with NNE-SSW trend in the middle of Korean peninsula. Three distinct fault-reactivated events of shallow crustal regime were recognized using the combined approach of optimized illite-polytype quantification and K-Ar age-dating of clay fractions separated from 4 fault clay samples: 87.0±0.12 Ma, 65.5±0.05 and 66.6±1.38 Ma, 45.6±0.15 Ma, respectively. As well, 2M1 illite ages of 193~196 Ma and 254.3±6.96 were discernible, which may be related to the fault-activated time in the relatively deep crust. The study results suggest that the Inje fault would be firstly formed at 254.3°æ6.96 Ma and sporadically reactivated in shallow regime since about 87 Ma. These reactivation events in shallow regime might be due to the Bulguksa orogeny that would be strongly influenced in Korean peninsula at that time.

Keywords Inje fault, K-Ar age-dating, fault clay, illite-age-analysis(IAA), Bulguksa orogeny

Article

Original Article

Econ. Environ. Geol. 2015; 48(1): 41-49

Published online February 28, 2015

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Reactivated Timings of Inje Fault since the Mesozoic Era

Chuluunbaatar Khulganakhuu1, Yungoo Song1*, Donghoon Chung1, Changyun Park1, Sung-Ja Choi2, Il-Mo Kang2, and Keewook Yi3

1Department of Earth System Sciences, Yonsei University, Seoul 120-749, Korea
2Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Korea
3Korea Basic Science Institute, Ochang Center, Ochang 363-883, Korea

Correspondence to:yungoo@yonsei.ac.kr

Received: February 16, 2015; Revised: February 25, 2015; Accepted: February 25, 2015

Abstract

Recently developed illite-age-analysis(IAA) approach was applied to determine the fault-reactivated events for the Inje fault that cut through Precambrian biotite granitic gneiss with NNE-SSW trend in the middle of Korean peninsula. Three distinct fault-reactivated events of shallow crustal regime were recognized using the combined approach of optimized illite-polytype quantification and K-Ar age-dating of clay fractions separated from 4 fault clay samples: 87.0±0.12 Ma, 65.5±0.05 and 66.6±1.38 Ma, 45.6±0.15 Ma, respectively. As well, 2M1 illite ages of 193~196 Ma and 254.3±6.96 were discernible, which may be related to the fault-activated time in the relatively deep crust. The study results suggest that the Inje fault would be firstly formed at 254.3°æ6.96 Ma and sporadically reactivated in shallow regime since about 87 Ma. These reactivation events in shallow regime might be due to the Bulguksa orogeny that would be strongly influenced in Korean peninsula at that time.

Keywords Inje fault, K-Ar age-dating, fault clay, illite-age-analysis(IAA), Bulguksa orogeny

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

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