关于纽芬兰寒武系-奥陶系界线层型候选剖面

<正> (一) 近几年来,加拿大纽芬兰西部寒武系-奥陶系界线剖面经过不少人的调查研究,可能作为国际寒武系-奥陶系界线层型的呼声很高。目前看来,只有中国吉林浑江大阳岔的寒武系-奥陶系界线剖面可以与之抗衡。 1986年7月下旬在吉林省浑江市召开了寒武系-奥陶系界线国际会议,各国代表对浑江大阳岔的小阳桥等几个寒武系-奥陶系剖面进行了仔细的观察和认真的讨论。几个剖面中以小阳桥剖面最为杰出,不仅地层出露良好,而且化石多,保存佳,尤其是笔石丰富多彩。深为国际同行所称道。冶里组底部一层新笔石的发现,更引入注目。林尧坤

Candidate for the Cambrian-Ordovician boundary stratotype of Newfoundland

Recently, at the Dayangcha Cambrian-Ordoviciar, boundary conference Dr. C. R. Barnes formally recommended the Broom Point North section of western Newfoundland as the candidate for the Cambrian-Ordovician boundary stratotype with the point defined at the first appearance of Cordylodus lindstromi Druce and Jones which is 1.6m above the base of Bed 17. This level lies just below the first appearance of nrmatophorous eraptolites in the section. Unfortunately the Broom Point North section is discontinuous in sedimentation and without earliest nematophorous graptolite Assemblage 1 as pointed out once more by Dr. B. D. Erdtmann based on his new investigation of the Cambrian-Ordovician boundary sections in western Newfoundland. The strikingly different views on the Broom Point North section ought to attract the attention of the International C-0 Boundary Working Group. This serious problem should be clarified.