摘要
滇西奥陶系潞西组顶部发现丰富的以Hirnantia magna为代表的"赫南特贝动物群",可作为奥陶系-志留系界线的划分标志。Hirnantia-Kinnella组合标志着冰川作用处于高潮期,海退显著,而仁和桥组笔石页岩相则是冰川消融、海平面快速上升后海侵作用所致,这一转换面上下岩性野外易识别,可近似代表滇西奥陶系-志留系界线野外填图划分界面。仁和桥组底部含Parakidograptus acuminatus,Neodiplograptus shanchongensis等化石,其时代为志留系兰多维列统。潞西地层小区与施甸地层小区的志留系研究对比表明,它们的沉积相特征差异明显,前者以碎屑岩为主,而后者碎屑岩与碳酸盐岩各占约1/2且岩石地层较连续,化石丰富。综上所述,滇西地区志留系的地层划分对比还有许多工作可做。
The Hirnantiafauna has been found in the Ordovician Luxi Formation for the first time in western Yunnan,with abundant specimens of Hirnantia magna that indicates a Hirnantian Stage（Upper Ordovician）.The Silurian Renheqiao Formation contains Parakidograptus acuminatus and Neodiplograptus shanchongensis,suggesting a Rhuddanian age（Early Siliurian）.The demise of the shallow and cool/cold water Hirnantiafauna coincides with the start of the continental glaciation in the Upper Ordovician,and the Renheqiao Fomation black graptolite shale facies indicates a deep-water,anoxic,and restricted sedimentary environment,caused by glacial retreat and sea level rise.The transition between these two facies represents the Ordovician-Silurian boundary.Comparison of strata in the Luxi and Shidian stratigraphic areas shows that there are significant differences in sedimentary-facies,with the former dominated by clastic facies and the latter by clastic and carbonate facies.
出处
《地层学杂志》
CSCD
北大核心
2014年第2期161-169,共9页
Journal of Stratigraphy
基金
中国地质调查局地质调查项目(1212010784008,1212011220390)联合资助
关键词
生物地层
赫南特贝动物群
奥陶系
志留系
保山
潞西(芒市)地区
滇西
biostratigraphy, Hirnantia fauna, Renheqiao Formation, Ordovician, Silurian, Baoshan,Luxi （Mangshi）, western Yunnan
