The Ordovician of the Korean Peninsula: a synthesis

Abstract

The Ordovician succession of the Korean Peninsula is part of the Cambro-Ordovician Joseon Supergroup exposed in the Taebaeksan Basin of South Korea and the Pyeongnam Basin of North Korea. This review summarises the advances made on these successions during the past two decades, focusing on the Taebaeksan Basin. The Ordovician succession in the Taebaeksan Basin comprises the Taebaek, Yeongwol, Yongtan, Pyeongchang, and Mungyeong groups, of which the Taebaek and Yeongwol groups have been studied in detail. These strata are mixed carbonate-siliciclastic deposits formed in peritidal to deep-subtidal environments. Sedimentological and palaeontological studies show that the Korean Ordovician succession represents local variations of the Great Ordovician Biodiversification Event, exemplified by reef evolution, changes in sedimentary systems, and changes in invertebrate fossil assemblages. Recent studies on the Yongtan, Pyeongchang, and Mungyeong groups have demonstrated that these units are important for understanding the tectonic evolution of the Taebaeksan Basin. The Ordovician strata in the Taebaek Group are generally similar to those of the Pyeongnam Basin and North China; however, the Upper Ordovician to Devonian strata between the two Korean basins show palaeontological affinities to those of South China, perhaps recording the Permo-Triassic collision between the Sino-Korean (North China) and South China blocks.

Goryeocrinus pentagrammos n. gen. n. sp. (Rhodocrinitidae; Diplobathrida), the first record of camerate crinoid from the Middle Ordovician (Darriwilian) of South Korea (East Gondwana)

“…The slab containing Goryeocrinus pentagrammos n. gen. n. sp. was found in an outcrop of the Middle Ordovician Jigunsan Formation, part of the Cambro-Ordovician Joseon Supergroup (Lee et al, 2022; Park et al, 2022). The formation mainly consists of mudstone with limestone layers in the upper part.…”

“…The formation mainly consists of mudstone with limestone layers in the upper part. The mudstone, which is dark gray and laminated, is interpreted to have been deposited in a low-energy, oxygen-restricted, clastic outer shelf and basin environment developed by rapid transgression (Woo and Chough, 2007; Byun et al, 2018; Lee et al, 2022). Specimens of G .…”

“…The Jigunsan Formation is the most fossiliferous Ordovician unit of the Joseon Supergroup, yielding various invertebrate fossils including trilobites, brachiopods, and cephalopods as major components (Lee et al, 2022). Minor components, such as echinoderms including Ohiocrinus (Park et al, 2022) and Goryeocrinus n. gen. described in this study, machaeridians, and possible soft-bodied fossils suggest that the Jigunsan fauna may have significant potential for understanding the East Gondwanan and Darriwilian aspect of the Great Ordovician Biodiversification Event, including early crinoid diversification.…”

Lithostratigraphic revision of the siliciclastic-dominated basal Taebaek Group (lower–middle Cambrian), Eastern Korea

“…Choi, 1998;see D.K. Choi, 2019 andJ.-H. Lee et al, 2023 for further discussion). The Taebaek Group has widely been regarded as the eastern end of the Sino-Korean Block on the basis of its palaeobiogeography (e.g., Jeong and Y.I.…”

“…Choi et al (2004) nominated the Seokgaejae section, which contains all the formations Lee et al, 2017). (B) Geological map of the Taebaeksan Basin (modified from J.-H. Lee et al, 2023).…”