OCCURRENCE OF PSEUDOGLYPTAGNOSTUS (CAMBRIAN TRILOBITA)IN SOUTH KOREA AND THE SIGNIFICANCE OFTHE SLOPE BIOFACIES OF KOREA
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Abstract:
Agnostus （Ptychagnostus？） orientalis Kobayashi 1935from the Olenoides Zone of the Machari Formationof South Korea is a species of Agnostotes （Pseudoglyptagnostus） Lu 1964 which is an agnostoid trilobite of medial Late Cambrian age rather than early Middle Cambrian．Kobayashi used the Olenoides to denominate a mixed zone of trilobites of Middle and Late Cambrian ages and his5biozonations for the Machari Formation are incorrect．The occurrence of Coreolenus Cheiruroides Oryctocephalus Pagetia Tonkinella Glyptagnostus Pseudoglyptagnostus and Hedinaspis of Early to Late Cambrian age in Chunghwa North Korea and in Neietsu and Bunkei South Korea shows the presence of a slopebiofacies which should be affiliated with the North China Platform as the side facing the Pacific Ocean．This slope biofaciesin Korea was the northeast extension of the Chiangnan Belt of South China where a continuous belt of slope biofacies withsouthwest-northeast direction existed from North Vietnam via southwest Guangxi eastern Guizhou western Hunan northern Jiangxi southern Anhui western Zhejiang southern Jiangsu （including Shanghai） to Korea．This belt is continu-ous without any serious geographical displacement．It clearly shows that the North China （or Sino-Korean） and Yangtze Platforms or “Blocks” of some authors have kept their northern and southern geographical positions as shown on the presentgeographical map they probably belonged to one larger platformal area and there is no separation of the North and SouthChina Blocks during the Cambrian as many authors have indicated in different reconstruction maps for Cambrian paleogeography （e．g．Lin Fuller and Zhang 1985 Zhao and Robert 1987）． Agnostus （ Ptychagnostus？） orientalis kobayashi and its associated species of Irvingella and Pseudagnostus are redescribed and refigured．Komaspis Kobayashi 1935may be a junior synonym of Irvingella Ulrich and Resser in Walcott 1924．Komaspis and Eochuangia are of LateCambrian Changshanian age rather than Middle Cambrian as suggested by Kobayashi in1935．
