Conodonts from the Sesong Slate and Hwajeol Formation(Guzhangian to Furongian) in the Taebaeksan Basin, Korea

Abundant conodont elements have been recovered from the Hwajeol Formation, to allow five zones to be erected： Proconodontus, Eoconodontus notchpeakensis, Cambrooistodus minutus, Cordylodus proavus, and Fryxellodontus inornatus-Monocostodus sevierensis-Semiacontiodus lavadamensis zones, in ascending order. More confident biozones are recognized in the Sesong Slate and lower Hwajeol Formation in the Makgol section, a part of the southern limb of the Baekunsan syncline, Taebaeksan Basin, Korea, especially focusing on the conodont biostratigraphic boundary of two units, and the subdivision potential of the previous ＂Proconodontus Zone＂, lowermost biozone of the Hwajeol Formation. Similarly, only a few conodont elements recovered from upper 14.5 m interval, namely the Furongian portion of the Sesong Slate, in the Makgol section did not allow erection of a biozone. Nevertheless, this part of the unit plus the basal 2.5 m interval of the Hwajeol Formation is characterized by the occurrence of Prooneotodus rotundatus（Druce and Jones）, Teridontus nakamurai（Nogami）, Phakelodus elongatus（An） and Phakelodus tenuis Müller. This interval marks the early Furongian ＂Prooneotodus rotundatus Zone＂. The rest of the measured section yielded relatively abundant conodonts, so three conodont biozones are proposed, based on the successive appearance of key species： Proconodontus tenuiserratus, Proconodontus posterocostatus, and Proconodontus muelleri zones, in ascending order, and thus allowing subdivision of the previous ＂Proconodontus Zone＂. The four conodont biozones are correlated with the relevant biozones of North and South China, and North America.

Stratigraphic Implications of Skeletal Microfossils from the Cambrian of Korea:A Preliminary Report

Diverse small shelly fossils and other associated fossils were recently recovered from the Cambrian Hanaeri section, southwestern Mungyeong, Korea. The fauna includes conoidal problematica, poriferans （sponge spicules）, coeloscleritophorans （chancelioriids）, brachiopods, monoplacophorans, trilobite （？） fragments, echinoderms, and conodonts. A preliminary assessment of faunal associations, stratigraphic implications, and the correlation of these skeletal fossils is given, based on occurrences of Actinotheca cf. mira （He）, Microcornus sp., Torellela laevigata （Linnarsson）, Torellela sp., Archiasterella quadratina Lee, Chancelloria sp., LinguleUa sp., Prototreta sp., Phakelodus tenuis （Miiller）, Phakelodus elongates （An）, Hertzina sp., and Furnishina sp.

Middle Cambrian (Upper Series 3)Protoconodonts and Paraconodonts from the Machari Formation at Eodungol Section,Yeongwol,Korea

The Machari Formation ranges from the ＂upper Series 3＂ （Middle Cambrian） to Furongian （Upper Cambrian） in the Yeongwol area, Korea. It has been known to yield relatively diverse invertebrate fossils. Particularly, the trilobite biozones of the formation have been well defined. On the other hand, little has hitherto been studied on conodont microfossils for the formation. This paper reports a diverse and well-preserved protoconodonts and paraconodonts of Series 3 from the formation in the Eodungol Section, exposed along a southern mountain trail of Mt. Sambangsan, Yeongwol, Korea. Five of the 13 samples collected for conodont contain a rich protoconodont and paraconodont assemblage and numerous shelly fossils including trilobites, brachiopods, sponge spicules, hyolithids, and incertae sedis. Sample Eo 5 is extremely fossiliferous （465 elements, 96.5% of total collection）, and the most abundant species was Phakelodus elongatus （236 elements, 62% of the Eo 5 collection）. The preservation is relatively good, but some specimens are corroded and fragmentary. Some of the protoconodonts are exfoliated. Relatively larger ones were commonly preserved as phosphatized internal molds, particularly in specimens of Furnishina bigeminata, Furnishina leei n. sp., Muellerodus pomeranensis, Nogamiconus sinensis, and westergaardodids. Phakelodids were commonly preserved as clusters. Among 20 species referable to nine genera, Furnishina bigeminata, Furnishina leei n. sp., Nogamiconus sinensis, Huayuanodontus tricornis, Proscandodus obliquus, and Westergaardodina grandidens were previously undescribed species in Korea. This assemblage is named herein as the Westergaardodina matsushitai Zone, which is a new biozonal name replacing the old one, i.e., Gapparodus bisulcatus-Westergaardodina matsushitai-Westergaardodina moessebergensis Assemblage. The W. matsushitai Zone corresponds to the Lejopyge armata trilobite Zone and is well correlated with the upper Series 3 conodont biozones of the Westergaardodina matsushitai-Westergaardodina grandidens Zone of South China and the Westergaardodina matsushitai Zone of North China, respectively. The present data allow a useful correlation to China and Baltica in relation to new subdivision of the Cambrian. Furnishina leei n. sp. is newly described.