Extensional deformation along the southern boundary of the Gyeonggi Massif, South Korea: Structural characteristics, age constraints, and tectonic implications

Raehee Han, Kyoungwon Min, Jin-Han Lee, David A. Foster

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Abstract

The Permo-Triassic collision of the North and South China blocks caused the development of the Dabie-Sulu Orogen in China and Songrim Orogen in the Korean Peninsula. Extension after this collision is known from the Dabie-Sulu Orogen, but post-orogenic extension is not well defined in the Korean Peninsula. Extensional deformation along the southern boundary of the Gyeonggi Massif in Korea is characterized by top-down-to-the-south ductile shearing and subsequent brittle normal faulting, and was predated by regional metamorphism and north-vergent contractional deformation. Extension occurred between ~220 and 185 Ma based on the ages of pre-extensional regional metamorphism and post-extensional pluton emplacement. 40Ar/39Ar dating of syn-extensional muscovite in quartz-mica mylonite yields an age of 187.8 ± 5.6 (2σ) Ma, in agreement with constraints from structural relationships. Together with the extensional deformation identified along the northern boundary of the Gyeonggi Massif (~226 Ma), the extension along the southern boundary is probably related to the exhumation of the massif during late-orogenic or post-orogenic extension associated with the Songrim Orogeny of the Korean Peninsula and forms an important event in the Phanerozoic crustal evolution of East Asia.

Original languageEnglish
Pages (from-to)757-776
Number of pages20
JournalInternational Journal of Earth Sciences
Volume103
Issue number3
DOIs
Publication statusPublished - 2014 Jan 1

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ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

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