Neoproterozoic Stratigraphic Sequence and Sedimentary Evolution at Qinglinkou Section,East Yangtze Gorges Area
An Zhihui
Tong Jinnan
Ye Qin
Tian Li
Song Huyue
Zhao Xiaoming
Abstract：The Yangtze Gorges area is one of the hot spots for the investigation of the Neoproterozoic in the world because of its well-preserved stratigraphic sequences recording the “Snowball Earth”,“Cap Carbonate”,and the “Miaohe Biota”.The Qinglinkou section presented in this paper is one of the typical best-outcropped Neoproterozoic sequences in the area,providing good condition for the study of the significant biotic evolution and environmental changes during the critical time.The sequence is in lithostratigraphy composed of the Liantuo,Nantuo,Doushantuo and Dengying formations.The Liantuo Formation includes two sedimentary cycles of purple sand-stones intercalated by some thin-bedded shale beds.The Nantuo Formation,uncomfortably overlying on the Liantuo Fm.,is character-istic of grayish green diamictites but a member of shale with a few“drop stones”intercalated in the middle part of the formation.The Doushantuo Formation can be well subdivided into four members,among which the first one is“Cap Carbonate”,the second dark dolo-mite interbedded with black shale,the third grey dolomite,and the last member black siliceous shale.The Dengying Formation is fea-tured by the “two white clipping one dark unit”and they correspond with the Hamaj ing,Shibantan and Baimatuo members respective-ly.The study of the sedimentary sequence and environmental markers at the Qinglinkou section indicates that the sedimentation in the area started in the Middle Neoproterozoic time and the early sediments were terrestrial facies while the marine facies did not occur until the end of the glaciation of the “Snowball Earth”represented by the Nantuo diamictites.The Ediacaran Doushantuo and Dengying for-mations are either shallow-sea carbonate or districted shale facies,which became the innovation base for the origin of metazoans and the diversification of macroalgae.
Keywords：Neoproterozoicstratigraphic sequencesedimentary environmentQinglinkouYangtze Gorges
Publication Date：2014-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：12( 795-806 )