重庆綦江白垩系夹关组遗迹化石及其沉积环境

The trace fossils and their sedimentary environments in the Cretaceous Jiaguan Formation,Qijiang,Chongqing

遗迹化石大都是原地埋藏,研究遗迹化石在古环境、古气候、古海洋和古生态等方面的重建具有重要的意义。綦江国家地质公园老瀛山园区夹关组地层中已发现的无脊椎动物遗迹化石经鉴定包括1大类3属3种,分别为觅食迹Scoyenia gracilis(纤细斯柯茵迹)、Beconites antarcticus(南极似塔形迹)和Planolites beverleyensis(贝弗利漫游迹)。这些遗迹化石都属于Scoyenia遗迹相,代表了研究区在白垩纪夹关期为间断性暴露地表的河漫滩或者滨浅湖环境。

The trace fossils are mostly autochthonously buried,and so it is significant to study the trace fossils for the reconstruction of palaeoenvironments,palaeoclimatology,palaeoceanography and palaeoecology. The present paper gives a detailed description of the types and sedimentary environments of the trace fossils,and may provide new trace fossil evidence for the sedimentary evolution of the Jiaguan Formation in Qijiang,Chongqing. The trace fossils examined in this study occur in the strata of the Cretaceous Jiaguan Formation in the Laoyingshan scenic area of the Qijiang National Geological Park,Qijiang,Chongqing,and consist of one ichnofacies,three ichnogenus and three ichnospecies i. e.,Scoyenia gracilis,Beconites antarcticus and Planolites beverleyensis. These trace fossils are assigned to the Scoyenia ichnofacies and represent the flood plain or littoral-shallow lake environments which are intermittently exposed to the surface in the deposition of the the Jiaguan Formation during the Cretaceous.