摘要
吉林辉南—和龙一线以南,龙岗背斜的两翼广泛出露华北型寒武纪和奥陶纪地层。背斜南翼为浑江流域(大阳岔、三道堡子、青沟子、木锨头沟等地)以大阳岔小杨桥寒武-奥陶系界线剖面最为完整。为寰球寒武-奥陶系界线层型的候选剖面之一(Kuo Hung-chun ＆others 1982;陈均远等 1985;Chen Jun-yuan ＆ others 1985,1986;Duan ＆ others1986;汪啸风、Erdtmann 1986;钱义元1987;赵祥麟等1988);北翼为三统河流域。
The Shansonggang Cambrian-Ordovician Boundary bed yields abundant graptolites,trilo-bites and ostracods, etc.. Four graptolite zones and subzones of the Cambrian-Ordovician Boundary bed (the basal part of Yehli Formation) may be recognized in descending order as follows: (2) Anisograptus richardsoni zone, (1)Dictyonema flabellijorme-Staurograptus dicho-omus zone, divided into two subzones, (b) Dictyonema flabelliiorme parabola and (a) Dictyonema proparabola. Dictyonema proparabola can be recognized as the earliest Ordovician floating graptolite. After studying the Dayangcha candidate international Cambrian-Ordovician Boundary Stratotype section, the writers think it better to put the Cambrian-Ordovician boundary just below the earliest appearence of nematophorous graptolite--Dictyonema fropara-bola.
出处
《地层学杂志》
CSCD
北大核心
1989年第2期138-143,共6页
Journal of Stratigraphy
