Geosciences Journal
Vol. 9, No. 2, p. 73−74, June 2005
Cambrian in the Land of Morning Calm
1. INTRODUCTION
The International Subcommission on Cambrian Stratig- raphy (ISCS) is a branch organization of the International Commission on Stratigraphy (ICS) and aims to complete and publish regional correlation charts for the Cambrian System and to establish a global stage-level chronostrati- graphic classification of the Cambrian System. As part of the activities, the ISCS arranged international field confer- ences of the Cambrian Stage Subdivision Working Group since 1995. To date, eight field conferences had been held in Morocco (1995), Spain (1996), Canada (1997), Sweden (1998), the Great Basin, USA (1999), Argentina (2000), South China (2001), and France (2002). These conferences certainly encouraged communications among the Cambrian specialists and helped understanding the Cambrian sequences around the world.
The 9th International Field Conference of the Cambrian Stage Subdivision Working Group was held at Taebaek- Yeongwol-Suanbo of Korea on September 15–22, 2004.
The conference consists of four-day field trip (Choi et al., 2004b) and five scientific sessions including oral and poster presentations (Choi, 2004). About 30 foreign participants from eight countries (China, Australia, United Kingdom, France, Germany, Sweden, Poland, and USA) and more than 20 Korean geologists were attending the meeting.
2. GUIDE TO THE TAEBAEKSAN BASIN
This four-day field trip introduced the Cambrian and Ordovician rocks and fossils of the Taebaeksan Basin, Korea, with emphasis on trilobites and sedimentological features. The Taebaeksan Basin was a low-relief shallow marine platform on which the Cambrian-Ordovician Joseon Supergroup was deposited.
On September 17, the Seokgaejae section, where a nearly complete succession of the Cambrian-Ordovician Taebaek Group is exposed, was examined (Choi et al., 2004a). Tri- lobites are commonly observed in some fossiliferous hori- zons. In the rainy morning of September 18, participants visited the Cambrian-Ordovician Taebaek Group in the Dongjeom section, which displays a lithologic succession different slightly from that of the Seokgaejae section. Day 3 (September 19) was a highlight of the trip in focusing on
the Upper Cambrian trilobites of the deeper water facies of the Machari Formation in Yeongwol. In addition, we briefly stopped the Deokpori thrust, which is one of the important faults within the Taebaeksan basin and separates the shal- low water Taebaek Group from the deep-water Yeongwol Group, and also one of the Cambrian-Ordovician boundaries in the Yeongwol Group exposed at the Garam section. Sep- tember 20 was a moving day from the Taebaeksan Basin to the southwest to the exotic terrane, Okcheon Belt, whose age and origins are controversial. On the way to Suanbo, we crossed a putatively very important tectonic feature in Korea, South Korean Tectonic Line (Chough et al., 2000), which has been suggested to represent the collisional suture between the two Precambrian massifs in the Permo-Triassic times.
3. CONTRIBUTIONS TO THE ISSUE
The scientific sessions include 17 oral presentations and 15 poster presentations (Choi, 2004). The current issue comprises eleven papers collected from the contributions for the conference. The first two papers (Palmer, 2005;
Geyer, 2005) discuss some philosophical aspects in apply- ing the current knowledge on the trilobite taxonomy and stratigraphy. Babcock et al. (2005) summarizes the current progress of the subdivision of the Cambrian System and proposes the Cambrian to be subdivided into four series and ten stages. Peng and Babcock (2005) reviewed two impor- tant agnostoid species, Agnostotes orientalis and Lotagnos- tus americanus, which can be utilized for establishing the uppermost two stages of the Cambrian.
The next three papers deal with regional aspects:
Paczes´ na and Poprawa (2005) explores the eustatic and tec- tonic controls of the Neoproterozoic to Cambrian sequences of Baltica based on sequence stratigraphic analysis; Holl- ingsworth (2005) describes a Lower Cambrian event bed composed almost exclusively of trilobites; and Álvaro and Clausen (2005) attempt to elucidate the relationships between the event stratigraphy, relative sea-level changes, stratigraphic discontinuities, and faunal replacements in the western Gondwana across the boundary interval of the conventional Lower-Middle Cambrian series. Elicki (2005) and Wotte (2005) describe in detail the small shelly fossil assemblages from the western Mediterranean regions and emphasize their utility in discussing the stratigraphy, paleogeography and paleoecology.
Duck K. Choi* School of Earth and Environmental Sciences, Seoul National University, Seoul 151-747, Korea
*Corresponding author: [email protected]
74 Duck K. Choi
The final two papers are contributions from Korea: Choi and Chough (2005) reviewed the up-to-date information on the Cambrian-Ordovician stratigraphy of the Taebaeksan Basin including the litho-, bio- and chrono-stratigraphy; and Hwang and Choi (2005) analyzed the heterochronic rela- tionship of two olenid trilobites from the Machari Forma- tion and its application for stratigraphic correlation.
ACKNOWLEDGEMENTS: Financial support for the conference was provided by School of Earth and Environmental Sciences (BK21), Seoul National University, Korea Research Foundation, Korea Feder- ation of Science and Technology Societies, City of Taebaek, and Insti- tute for Cambrian Studies. Contributors of abstracts and manuscripts are gratefully acknowledged for their efforts. Thanks are extended to the reviewers for this issue: P. Ahlberg, J.J. Álvaro, L.E. Babcock, D.K. Choi, G. Geyer, J.B. Jago, P.A. Jell, E. Landing, D.C. Lee, D.-J.
Lee, L.B. McCollum, M. Moczyd owska-Vidal, A.R. Palmer, S. Peng, R.A. Robison, I.C. Ryu, J.H. Shergold, F.A. Sundberg, and K.S. Woo.
REFERENCES
Álvaro, J.J. and Clausen, S., 2005, Major geodynamic and sedimen- tary constraints on the chronostratigraphic correlation of the lower-middle Cambrian transition in the western Mediterranean region. Geosciences Journal, 9, 145–160.
Babcock, L.E., Peng, S., Geyer, G. and Shergold, J.H., 2005, Chang- ing perspectives on Cambrian chronostratigraphy and progress toward subdivision of the Cambrian System. Geosciences Jour- nal, 9, 101–106.
Choi, D.K., ed., 2004, Cambrian in the Land of Morning Calm. 9th International Conference of the Cambrian Stage Subdivision Working Group (Abstracts with Program), Taebaek, Korea, 71 p.
Choi, D.K. and Chough, S.K., 2005, The Cambrian-Ordovician stratig- raphy of the Taebaeksan Basin, Korea: a review. Geosciences Jour- nal, 9, 187–214.
Choi, D.K., Chough, S.K., Kwon, I.K., Lee, S.-B., Woo, J., Kang, I., Lee, H.S., Lee, S.M., Sohn, J.W., Shinn Y.J. and Lee, D.-J., 2004a, Taebaek Group (Cambrian-Ordovician) in the Seokgaejae
section, Taebaeksan Basin: a refined lower Paleozoic stratigraphy in Korea. Geosciences Journal, 8, 125–151.
Choi, D.K., Chough, S.K., Fitches,W.R., Kwon, Y.K., Lee, S.-B., Kang, I., Woo, J., Shinn, Y.J. and Sohn, J.W., 2004b, Field Trip Guide for Ninth International Conference of the Cambrian Stage Subdivision Working Group. Cambrian in the Land of Morning Calm, The Paleontological Society of Korea, Special Publication, 8, Daegu, September 15–22, 75 p.
Chough, S.K., Kwon, S.-T., Ree, J.-H. and Choi, D.K., 2000, Tec- tonic and sedimentary evolution of the Korean peninsula - a review and new view. Earth-Science Reviews, 52, 175–235.
Elicki, O., 2005, The utility of late Early to Middle Cambrian small shelly fossils from the western Mediterranean. Geosciences Jour- nal, 9, 161–171.
Geyer, G.., 2005, The base of a revised Middle Cambrian: Are suit- able concepts for a series boundary in reach? Geosciences Jour- nal, 9, 81–99.
Hollingsworth, J.S., 2005, A trilobite fauna in a storm bed in the Poleta Formation (Dyeran, Lower Cambrian), Western Nevada, U.S.A. Geosciences Journal, 9, 129–143.
Hwang, H.-A. and Choi, D.K., 2005, Heterochrony of the Late Cam- brian olenid trilobites from the Machari Formation, Yeongwol, Korea: implications for biostratigraphy and intercontinental cor- relation. Geosciences Journal, 9, 215–222.
Paczes´ na, J. and Poprawa, P., 2005, Eustatic versus tectonic control on the development of Neoproterozoic and Cambrian strati- graphic sequences of the Lublin-Podlasie Basin (SW margin of Baltica). Geosciences Journal, 9, 117–127.
Palmer, A.R., 2005, East-Gondwana/Laurentia trilobite connections – What do they tell us? Geosciences Journal, 9, 75–79.
Peng, S. and Babcock, L.E., 2005, Two Cambrian agnostoid trilobites, Agnostotes orientalis (Kobayashi, 1935) and Lotagnostus amer- icanus (Billings, 1860): Key species for defining global stages of the Cambrian System. Geosciences Journal, 9, 107–115.
Wotte, T., 2005, Facies distribution patterns and environment recon- struction of the upper member of the Láncara Formation in the Somiedo-Correcilla unit (Lower–Middle Cambrian, Cantabrian zone, NW Spain) with special respect to biofacial investigations.
Geosciences Journal, 9, 173–186.
l
