Geology of the 2018 Winter Olympic site, Pyeongchang, Korea

ABSTRACT

We review the geology of the Gyeonggi Massif, Gyeonggi Marginal Belt, and Taebaeksan Basin of the Korean Peninsula, which are relevant to the 2018 Winter Olympic sites. Neoarchaean–Palaeoproterozoic gneisses and schists of the Gyeonggi Massif underwent two distinct collisional orogenies at the Palaeoproterozoic (1.88–1.85 Ga) and Triassic (245–230 Ma). These basement rocks are structurally overlain by a suite of Mesoproterozoic to Early Permian supracrustal rocks of the Gyeonggi Marginal Belt, consisting primarily of medium-pressure schists and amphibolites metamorphosed at ~270–250 Ma. In contrast, sedimentary successions in the Taebaeksan Basin, commonly fossiliferous, consist primarily of Early Cambrian–Middle Ordovician Joseon Supergroup and Late Carboniferous–Early Triassic Pyeongan Supergroup. The ‘Great Hiatus’ between the two supergroups is characteristic for the North China Craton. The marked contrast in tectonometamorphic evolution between the Taebaeksan Basin and Gyeonggi Marginal Belt suggests an existence of major suture in-between, which is most likely produced by the Permian–Triassic continental collision between the North and South China cratons. Finally, recent tectonics of the Korean Peninsula is governed by the opening of East Sea/Sea of Japan during the Late Oligocene–Early Miocene. This back-arc rifting event has resulted in an exhumation of the Taebaek Mountain Range, estimated to be 22 ± 3 Ma on the basis of apatite (U–Th)/He ages. Thus, high topography in the 2018 Winter Olympic sites is the consequence of Tertiary tectonics associated with the opening of a back-arc basin.

KEYWORDS:

• Pyeongchang
• 2018 Winter Olympic
• Permian–Triassic orogeny
• Oligocene–Miocene uplift
• Gyeonggi Massif
• Gyeonggi Marginal Belt
• Taebaeksan Basin
• Korean Peninsula
• North China Craton

Acknowledgements

We thank Wonseok Cheong for his tremendous help with the artwork drafting all the figures. We also acknowledge the insightful and constructive comments of journal reviewers, Peter Cawood and Tatsuki Tsujimori, as well as the editor-in-chief, Bob Stern. In particular, we thank Bob Stern for his genuine interest in the Korean geology and continuous support for writing up this paper. Without his help, this paper could not be completed.

Disclosure statement

No potential conflict of interest was reported by the authors.