摘要
据遗迹化石新资料 ,将内蒙古桌子山地区中奥陶世公乌素组遗迹化石自下而上划分为 8个组合 :Taenidium组合、Zoophycos组合、Volkichnium组合、H elminthopsis-Paleodictyon组合、Granularia组合、 Circulichnus组合、 Chondrites组合及 H elminthopsis组合。其中 ,H elminthopsis-Paleodictyon与 H elminthopsis两组合属于 N ereites遗迹相 ,并分别出现于陆隆 -深海盆地浊积扇与陆隆浊积扇环境 ;其余 6个组合与 Seilacher( 1 967)的 Zoophycos遗迹相相当 ,代表有机质丰富、平静而贫氧的大陆斜坡环境。遗迹组合序列和遗迹相的递变表明 ,本区在公乌素组沉积期经历了两次由陆棚边缘盆地—大陆斜坡—陆隆 -深海盆地浊积扇 (或陆隆浊积扇 )的环境演变。指出了本组遗迹化石与波兰喀尔巴阡山复理石相遗迹化石在分布上的相似性。认为 Zoophycos相各遗迹组合所赋存的泥灰岩等是很好的生油岩。
Based on the new data,the trace fossils in Middle Ordovician Gongwusu Formation,Zhuozishan,Inner Mongolia are grouped into eight trace fossil assemblages from bottom to top,i.e., Taenidium,Zoophycos, Volkichnium,Helminthopsis Paleodictyon,Granularia,Circulichnus,Chondrites and Helminthoposis assemblages.Among them, Helminthopsis Paleodictyon and Helminthopsis assemblages are referred to Nereites ichnofacies and occur respectively in turbidite fans either of continental rise deep sea basin or of continental rise.Corresponding to the Zoophycos ichnofacies proposed by Seilacher(1967),other six assemblages indicate the organic matter rich and oxygen poor stagnant continental slope environment.It is suggested that this region had experienced two enviromnental changes from borderbasin of continental shelf via continental slope to continental rise deep sea basin and from borderbasin of continental shelf via continental slope to continental rise during the sedimentary period of the Gongwusu Formation.It is found that the distribution of trace fossils in the Gongwusu Formation is obviously similar to that of the flysch trace fossils in the Polish Carpathians(Ksiazkiewicz,1977)and the marls containing the trace fossil assemblages of Zoophycos ichnofacies are probably potential source rocks for petroleum.
出处
《现代地质》
CAS
CSCD
北大核心
2000年第3期366-372,共7页
Geoscience
基金
中国石油天然气总公司勘探研究项目
关键词
遗迹化石组合
古地理演化
中奥陶世
公乌素组
trace fossil assemblage
ichnofacies
depositional environment
paleogeographic evolution
Middle Ordovician
the Gongwusu Formation
Inner Mongolia
