Journal of the Geological Society of Korea (지질학회지)

The Geological Society of Korea (대한지질학회)
권호 표지

Shear Criteria in Mylonites from the Soonchang Shear Zone, the Hwasun Coalfield, Korea

순창전단대에 발달된 전단지시자에 대한 고찰

Kee, Weon-Seo;Kim, Jeong-Hwan
기원서;김정환

  • Published : 19920800

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Abstract

The Soonchang Shear Zone (SSZ) is the one of the major ductile shear zones in the Korean Peninsula. The mylonites from the shear zone in the Hwasun Coalfield area have been derived from the Precambrian granitic gneisses, late Paleozoic metasediments and metaporphyries, and contain a distinctive assemblages of mesoscopic and microscopic asymmetric structures which are genetically related to the shearing processes. These structures, used to deduce the sense of shear in the shear zone, include the trajectories of generated mylonitic foliations in granitic gneisses, porphyroclast systems, asymmetric pressure fringes, composite fabrics, oblique shape fabrics of elongated recrystallized grains, displaced broken grains, asymmetric inclusion trails and intrafolial microfolds. These are reliable for the determination of the sense of shear in the study area where no displaced marker horizon can be found. All of these structures with asymmetric textural features reflect the non-coaxial deformation history, and indicate a consistent dextral shearing along the Soonchang Shear Zone.

순창전단대는 한반도 남부에 발달되어 있는 주요 연성전단대 중의 하나로서, 그 연장의 일부지역인 화순탄전지역에는 선캠브리아기의 화강암질 편마암, 고생대 후기의 변성퇴적암 및 변성반암에서 유래된 압쇄암류가 전단대를 따라 잘 발달되어 있다. 이 압쇄암류내에는 전단작용에 수반되어 발달한 여러 형태의 비대칭구조들이 함유되어 있어, 뚜렷한 변위층준이 존재하지 않는 연구지역에서의 전단대의 운동방향을 결정하는데 유용하게 이용되었다. 전단지시자로 이용된 구조들의 비대칭적인 기하학적 형태 및 미구조적 특징들은 이축성의 연성변형작용을 반영하고 있으며, 일정하게 우수향의 운동방향을 기록하고 있다.

Keywords

References

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