摘要
曲靖地区志留—泥盆纪地层连续沉积，生物门类丰富，长期以来倍受国内外地质学家关注。笔者根据层序地层学理论和研究方法，在关底组至翠峰山组西山村段之间确定了３个三级相对海平面变化旋回（层序），这些三级旋回（层序）和旋回边界（层序边界）与Ｖａｉｌ等（１９７７）确定的全球性相对海平面变化旋回有很好的可比性。据此，结合生物组合分析曲靖地区志留系的年代界线为：（１）ＳＤ界线在玉龙寺组第二段之底（上易剥页岩之底、最大海泛面），但有一枚卢德洛上带化石Ｏｚａｒｋｏｄｉｎａｃｒｉｓｐａ出现在于上易剥页岩的中部；（２）ＰｒｉｄｏｌｉａｎＬｕｄｌｏｖｉａｎ界线置于妙高组第二段之底（第三个层序边界）；（３）ＬｕｄｌｏｖｉａｎＷｅｎｌｏｃｋｉａｎ界线置于关底组第一段上部（第二个层序边界）。
Based on the theory and study method of sequence stratigraphy, we discovered three 3rd order relative sea level changes from the Xishancun Member of the Guandi Formation to the Cuifengshan Formation.The 3rd order cycels may be well correlated with the global cycles of relative sea level changes(Vail et al.,1977).Based on this correlation and the biologic assemblages,the Silurian chronostratigraphic boundaries are determined as follows:(1)Silurian Devonian boundary is placed at the base of the second member of the Yulongsi Formation (the base of the upper black shale,maximum marine flooding surface),but that there is a conodont fossil (Ozarkodina crispa)in the middle part of the upper black shale;(2)Pridolian Ludlovian boundary placed at the base of the second member of the Miaogao Formation (3rd sequence boundary);(3)Ludlovian Wenlockian boundary placed at the upper part of the first member of the Guandi Formation(2nd sequence boundary).
出处
《地层学杂志》
CSCD
北大核心
1997年第1期68-76,共9页
Journal of Stratigraphy
关键词
志留纪
年代地层界线
海平面变化
层序地层
Silurian, correlation, sea level change, sequence stratigraphy, Yunnan
