• 责任者：Li Xiangdong (School of Geoscience ; Yangtze University ; Jingzhou 434023 ; China) ; He Youbin
• 刊名：Acta Geologica Sinica
• 出版年：2011
• 卷期：85(4)
• 关键词：沉积序列 ; sedimentary sequence ; 宁夏 ; Ningxia
• 页码：p.516-525
• 图表：6 illus., 1 table, 34 refs.
• 分类号：0803
• issnNo：ISSN0001-5717
• isbnNo：CN11-1951/P

This paper reports the basic unit of Xujiajuan Formation of the Xiangshan Group, Ningxia, China. This unit is divided into a lower dense flow deposit division(Ⅰ), an intermediate traction flow deposit division(Ⅱ), and an upper suspension deposit division(Ⅲ). The results show that:  1) divisionⅠis composed of fine-grained sandstone and silty sandstone with no obvious separation of grain-size in different bed thickness; 2) fine-grained sandy siltstone is very poorly developed, thus, the grain-size break between divisionⅠand divisionⅡwas occurred; 3)  perfect divisionⅡincludes two series of cross beddings, one is parallel and quasi-planar and combined-flow-ripple lamination and small-scale hummocky cross stratification, the other is unidirectional and bi-directional cross lamination and parallel lamination; and 4) micrites in division Ⅲ exhibit lenticular thin bedding with irregular surface at the bottom.