• Geosciences Journal
• /
• v.23 no.4
• /
• pp.547-556
• /
• 2019

A new species of the most primitive rosenellid stromatoporoid Cystostroma, C. primordia sp. nov. is reported from the Hunghuayuan Formation (Lower Ordovician, Floian) of Guizhou Province in the South China Block and the Duwibong Formation (Middle Ordovician, Darriwilian) of the Taebaeksan Basin in mid-eastern Korea (North China Block). This species is the first representative of the genus found in both the North and South China blocks. Cystostroma primordia sp. nov. is characterized by the absence of denticles and distinctively smaller cyst plates (height 0.04-0.20 mm, length 0.09-0.39 mm) than any other known species of Cystostroma. The presence of C. primordia sp. nov. in Lower to Middle Ordovician strata of western Gondwana challenges the long-held view of the late Middle Ordovician emergence of Paleozoic stromatoporoids. The simple internal morphological features of this new species and its occurrence in the Lower Ordovician of South China strongly indicate that an Early Ordovician Cystostroma-type precursor from western Gondwana is located near the base of the stromatoporoid stock. This occurrence greatly preceded the late Middle Ordovician (late Darriwilian) stromatoporoid diversification in circum-equatorial regions worldwide.

• Journal of the Korean earth science society
• /
• v.27 no.7
• /
• pp.745-756
• /
• 2006

Early Ordovician graptolites from the Mungok Formation of Yeongwol area, Korea comprise seven species belonging to six genera: Callograptus curvithecalis, Callograptus sinicus, Aspidograptus lotolatzensis, Dendrograptus suni, Dictyonema uniforme, Adelograptus cf. tenellus, and Psigraptus jacksoni. Two graptolite zones with three subzones are recognized in the eight sections of the Mungok Formation. The Adelograptus Zone is correlated with (1) La 1b of the Lancefield Formation of Victoria, Australia, (2) the Adelograptus-Clonograptus Zone of the Yehli Formation of Jilin, China, and (3) the Adelograptus Zone of the Road River Formation of Yukon, Canada. It suggests that the upper part of the Mungok Formation corresponds to early Late Tremadocian of Early Ordovician.

• Journal of the Korean earth science society
• /
• v.28 no.5
• /
• pp.603-612
• /
• 2007

Lower Ordovician (Upper Tremadoc) graptolites were found for the first time at the two sections of the Mungok Formation in Danyang area: the Seokgyori and Daejeonri sections. The graptolites from these sections comprise two species of two genera: Adelograptus brevibrachiatus and Psigraptus jacksoni. The graptolite faunas of the sections in the area show simple composition relative to Yeongwol area; they appear to be correlated to: (1) the Adelograptus cf tenellus Zone of Yeongwol area, (2) the Adelograptus cf. tenellus Zone of Yukon, Canada, (3) the Psigraptus Zone of Tasmania, Australia, and (4) the Psigraptus jacksoni Zone of Jilin, China. The age of graptolite beds of the Mungok Formation at Danyang appears to be early Upper Tremadoc of the Lower Ordovician.

• Economic and Environmental Geology
• /
• v.3 no.1
• /
• pp.9-15
• /
• 1970

This paper describes the definition of the Ogcheon Group and its characters, and indicates that it is neither the Precambrian nor metamorphosed Cambro-Ordovician sediments, and its geological age might fall in Post-Ordovician on the bases of lithostratigraphy, correlation and geological structures.

• Journal of the Korean earth science society
• /
• v.30 no.5
• /
• pp.646-659
• /
• 2009

The early Ordovician graptolites from the upper part (Tumok Member) of the Mungok Formation of the Namaeri and Baeiljae sections at Yeongwol consist of five species belonging to five genera. They are Adelograptus cf. tenellus, Callograptus sp., Dendrograptus suni, Dictyonema sp., and Psigraptus jacksoni. Of these 5 species, Psigraptus is the most excellent index fossil for international correlation with the early Ordovician strata. Adelograptus cf. tenellus from the Mungok Formation of the Namaeri and Baeiljae sections is also recognized with especially short stipe relative to Adelograptus tenellus. Three graptolite zones (such as Adelograptus, Psigraptus, and Dendroid type zones) are correlated with those of Canada, Australia, and China, respectively. The upper part of the Mungok Formation is assigned to the late Tremadocian.

• 한국지구과학회:학술대회논문집
• /
• 2004.02a
• /
• pp.58-58
• /
• 2004

• 한국지구과학회:학술대회논문집
• /
• 2005.09a
• /
• pp.159-160
• /
• 2005

• 한국지구과학회:학술대회논문집
• /
• 2005.09a
• /
• pp.451-451
• /
• 2005

• 한국지구과학회:학술대회논문집
• /
• 2006.02a
• /
• pp.116-117
• /
• 2006

• 한국석유지질학회:학술대회논문집
• /
• autumn
• /
• pp.51-51
• /
• 2000