Dong Chan Lee

Early Ordovician reefs from the Taebaek Group, Korea: constituents, types, and geological implications

The Early Ordovician (early to middle Floian) bioherms of the Dumugol Formation, Korea, are compiled and their paleoenvironmental and paleogeographic implications are discussed. These reefs are mostly made up of microbialite (stromatolite and thrombolite) and lithistid sponge Archaeoscyphia, with subordinate “receptaculitid” calathids. Three types of reefs are identified based on biotic association and texture: 1) lithistid sponge-microbialite, 2) microbialite (thrombolite) with minor lithistid sponge, and 3) lithistid sponge-microbialite-calathid. The first and third type reefs are surrounded by intraclastic-skeletal packstone to grainstone and overlain by lime mudstone, whereas the second type reefs are surrounded and overlain by bioturbated wackestone and nodulebearing shale. These relationships appear to reflect varying depositional conditions during development of the reefs. The constituents of the Dumugol reefs are roughly comparable to coeval structures of Laurentia and South China with the exception of the absence of incorporated sessile organisms (i.e., Lichenaria, Pulchrilamina, and bryozoan) and delayed arrival (more than 10 myr) of calathids in the Sino-Korean Craton. This temporal disparity of biotic appearance is probably related to differential dispersal rates and patterns of sessile organisms which are largely controlled by the relative position of landmasses, epicontinental seas and major oceans. Further discovery and study of the Early Ordovician reefs from the Sino-Korean Craton will provide crucial information for understanding migration pathways of sessile organisms and paleogeographic reconstruction of the western margin of Gondwana in the Early Paleozoic.

Where art thou “the great hiatus?” — review of Late Ordovician to Devonian fossil-bearing strata in the Korean Peninsula and its tectonostratigraphic implications

We review paleontologic evidence from the Upper Ordovician to Devonian strata in the Korean Peninsula and discuss their tectonostratigraphic origin. The Upper Ordovician–Devonian fossil-bearing strata are largely distributed in North Korea, and tectonostratigraphically in the southern margin of the Pyeongnam Basin and in the northern part of the Imjingang Belt. The fossils have been regarded as evidence that the “great hiatus” of the middle Paleozoic is not a prevalent phenomenon across the Sino-Korean Block. Examination of selected fossils with stratigraphic and paleogeographic significance reveals that the fossils from the Sangsori, Koksan and Wolyangri series and the Rimjin System are of the Late Ordovician to Devonian and display affinity to those of the coeval strata of South China. In addition, the fossils included within clasts of the Songrim Conglomerate, the basal unit of the Jurassic Taedong System, are of the Silurian to Devonian, which also display affinity to South China. The faunal and floral affinity suggests that the Upper Ordovician to Devonian strata in North Korea most likely formed in a basin(s) of or peripheral to the South China Block, which indicates that the strata are allochthonous, contrary to the traditional interpretation of their autochthonous origin by North Korean geologists. The Permo-Triassic collision between the two Chinese cratons which resulted in the amalgamation of three massifs of the Korean Peninsula is considered to be responsible for the accretion and juxtaposition of the Upper Ordovician to Devonian strata onto the Sino-Korean Block. The autochthonous origin of the strata suggests the absence of the “great hiatus” at least in North Korea, whereas the allochthonous origin its presence across the Sino-Korean Block.

Morphometrics and palaeoecology of the coral Agetolites from the Xiazhen Formation (Upper Ordovician), Zhuzhai, South China

Sun, N., Elias, R.J., Choh, S.-J., Lee, D.-C., Wang, X.-L. & Lee, D.-J., February 2016. Morphometrics and palaeoecology of the coral Agetolites from the Xiazhen Formation (Upper Ordovician), Zhuzhai, South China. Alcheringa 40, xxx–xxx. ISSN 0311-5518. Agetolites is a peculiar cerioid coral possessing traits of both tabulates and rugosans. The presence of numerous mural pores has been considered by some workers to indicate a relation to tabulates, although an affinity to rugosans has also been proposed based mainly on well-developed septa that alternate in length. Agetolites is by far the most common colonial coral in the Upper Ordovician Xiazhen Formation at Zhuzhai, in the JCY (Jiangshan–Changshan–Yushan) triangle region of South China. It occurs in various lithofacies representing a wide range of depositional environments. Five species are recognized and verified by cluster analysis, discriminant analysis, descriptive statistics and bivariate plots: A. yushanensis Lin, 1960, A. raritabulatus Lin, 1960, A. waicunensis (Lin & Chow, 1977), A. oculiporoides Lin, 1960 (including A. huangi Lin, 1960 as a junior synonym) and A. maxima (Lin & Chow, 1977). Agetolitids from the JCY triangle described previously under the generic name Agetolitella are herein transferred to Agetolites. In the Xiazhen Formation at Zhuzhai, A. waicunensis and A. maxima are restricted to the lower part of the formation, whereas A. yushanensis occurs in the upper part. Agetolites raritabulatus and A. oculiporoides have greater stratigraphic ranges in the lower and upper parts of the formation. The size and shape of Agetolites coralla at Zhuzhai are considered primarily to be intrinsic characteristics of the species but in some cases also seem to be related to lithofacies; large and domical coralla are dominant in calcareous mudstone facies, whereas small coralla with various forms are commonly found in reef or reef-related facies. In the latter facies, spatial competition is indicated by common occurrences of both Agetolites encrusting stromatoporoids and stromatoporoids encrusting Agetolites. Ning Sun [nsun@cugb.edu.cn], School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, PR China; Robert J. Elias [eliasrj@cc.umanitoba.ca], Department of Geological Sciences, The University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada; Suk-Joo Choh [sjchoh@korea.ac.kr], Department of Earth and Environmental Sciences, Korea University, Seoul 136-701, Korea; Dong-Chan Lee [dclee@chungbuk.ac.kr], Department of Earth and Environmental Sciences, Chungbuk National University, Cheongju, 361-763, Korea; Xun-Lian Wang [wxl@cugb.edu.cn], School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, PR China; Dong-Jin Lee* [djlee@andong.ac.kr], Department of Earth and Environmental Sciences, Andong National University, Andong 760-747, Korea. *Also affiliated with College of Earth Science, Jilin University, Changchun 130061, PR China.

Morphometrics and paleoecology of Catenipora (Tabulata) from the Xiazhen Formation (Upper Ordovician), Zhuzhai, South China

Abstract Catenipora is one of the most common tabulate coral genera occurring in various lithofacies in the Upper Ordovician Xiazhen Formation at Zhuzhai in South China. A combination of traditional multivariate analysis and geometric morphometrics is applied to a large number of specimens to distinguish and identify species. Based on three major principal components extracted from 11 morphological characters, three major groups as determined by the cluster-analysis dendrogram are considered to be morphospecies. Their validity and distinctiveness are confirmed by discriminant analysis, descriptive statistics, and bivariate plots. Tabularium area and common wall thickness are the most meaningful characters to distinguish the three morphospecies. Geometric morphometrics is adopted to compare the morphospecies with types and/or figured specimens of species previously reported from the vicinity of Zhuzhai. Despite discrepancies in corallite size, principal component analysis and discriminant analysis, as well as consideration of overall morphological characteristics, indicate that the morphospecies represent C. zhejiangensis Yu in Yu et al., 1963, C. shiyangensis Lin and Chow, 1977, and C. dianbiancunensis Lin and Chow, 1977. Catenipora occurs in seven stratigraphic intervals in the Xiazhen Formation at Zhuzhai, representing a variety of heterogeneous environments. The coralla preservation is variable due to differential compaction; coralla preserved in limestones are commonly intact and in growth position, whereas those in shales are mostly crushed or fragmentary. The size and shape of corallites are considered primarily to be species-specific characters, but are also related to the depositional environments. In all species, morphological characters, including corallite size, septal development, and shape and size of lacunae, show high variability in accordance with lithofacies and stratigraphic position. The intraspecific differences in corallite size at various localities in the Zhuzhai area may indicate responses to local environmental factors, but may also reflect genetic differences if there was limited connection among populations.

Revised conodont and fusuline biostratigraphy of the Bamchi Formation (Pyongan Supergroup) at the Bamchi section, Yeongwol and the Carboniferous–Permian boundary in South Korea

Wang, Q., Wang, Y., Qi, Y., Wang, X., Choh, S.J., Lee, D.C. & Lee, D.J., November 2017. Yeongwol and the Carboniferous–Permian boundary in South Korea. Alcheringa 42, 245–258. ISSN 0311-5518 Six conodont and one fusuline zones are recognized on basis of a total of 25 conodont and 13 fusuline species (including seven unidentified species or species given with cf. or aff. in total) from the Bamchi Formation, Yeongwol, Korea. The conodont zones include the Streptognathodus bellus, S. isolatus, S. cristellaris, S. sigmoidalis, S. fusus and S. barskovi zones in ascending order, which can be correlated with the conodont zones spanning the uppermost Gzhelian to Asselian Age of the Permian globally. The fusuline zone is named the Rugosofusulina complicata–Pseudoschwagerina paraborealis zone. The co-occurrence of the conodont Streptognathodus isolatus (the Global Boundary Stratotype Section and Point index for the base of Permian) and Pseudoschwagerina (a Permian inflated fusuline) indicates that the Carboniferous–Permian boundary can be placed in the lower part of the Bamchi Formation in South Korea. Qiulai Wang* [qlwang@nigpas.ac.cn] CAS Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, East Beijing Road 39, Nanjing 210008, PR China; Yue Wang* [yuewang@nigpas.ac.cn] LPS, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, East Beijing Road 39, Nanjing 210008, PR China; Yuping Qi* [ypqi@nigpas.ac.cn] Xiangdong Wang* [xdwang@nigpas.ac.cn] CAS Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, East Beijing Road 39, Nanjing 210008, PR China; Suk-Joo Choh [sjchoh@korea.ac.kr] Department of Earth and Environmental Sciences, Korea University, Seoul 02841, Republic of Korea; Dong-Chan Lee [dclee@chungbuk.ac.kr] Department of Earth Sciences Education, Chungbuk National University, Cheongju 28644, Republic of Korea; Dong-Jin Lee [djlee@andong.ac.kr] Department of Earth and Environmental Sciences, Andong National University, Andong 36729, Republic of Korea. *Also affiliated with: University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, PR China.

Systematic Revision of Trilobites from the Middle Ordovician (Darriwilian) Klimoli Formation of the Zhuozishan Area, Inner Mongolia, China

New morphologic information permits systematic revision of trilobites from the Middle Ordovician Klimoli Formation of the Zhuozishan area, Ordos Basin, Inner Mongolia. The new assemblage is composed of 10 species of the Raphiophoridae, Nileidae, Asaphidae, and Telephinidae. An asaphid, aff. Mioptychopyge lashachungensis (previously Paraptychopyge lashachungensis) displays an intermediate morphology between the Chinese nobiliasaphine genera Mioptychopyge and Zhenganites. The pygidial doublure is regarded as the most significant character to differentiate Symphysurus klimoliensis (previously Nileus klimoliensis) of the Nileidae from such closely allied taxa as Poronileus. A nileid, cf. Peraspis kujandensis displays typical nileid morphology, unlike the type species, Peraspis lineolata, which might turn out to be an asaphid. Ampyx gongwusuensis sp. nov. of the Raphiophoridae is the first record of the genus in the Zhuozishan area and reveals morphologic details that might be employed to resolve Ampyx taxonomy in China. Morphologic differences between A. gongwusuensis and Abulbaspis ordosensis might represent a case of sexual dimorphism.