Advances in Earth Science ›› 2019, Vol. 34 ›› Issue (12): 1301-1315. doi: 10.11867/j.issn.1001-8166.2019.12.1301

Previous Articles     Next Articles

Deep-water Combined-flow Deposits of the Upper Ordovician Lashenzhong Formation in Zhuozishan Area, Western Margin of Ordos Basin

Xiangdong Li( ),Haiyan Chen,Hongda Chen   

  1. School of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China
  • Received:2019-09-29 Revised:2019-11-18 Online:2019-12-10 Published:2020-02-12
  • About author:Li Xiangdong (1973-), male, Lantian County, Shaanxi Province, Associate professor. Research areas include marine sedimentology. E-mail:
  • Supported by:
    the National Natural Science Foundation of China “Study of the evolution of turbidity currents and its interaction with internal waves of Middle and Upper Ordovician on the southeastern margin of Alxa Block and western margin of Ordos Basin”(41272119);The Science Foundation of Yunnan Provincial Department of Education “Sedimentary hydrodynamics for preservation of soft impression fossil in Chengjiang Fauna”(2015Z030)

Xiangdong Li,Haiyan Chen,Hongda Chen. Deep-water Combined-flow Deposits of the Upper Ordovician Lashenzhong Formation in Zhuozishan Area, Western Margin of Ordos Basin[J]. Advances in Earth Science, 2019, 34(12): 1301-1315.

The research of deep-water combined-flow deposits is still in its infancy at present, which has great significance for discovering new case study and discussing the indication effects of combined-flow sedimentary structures on depositional environment. The Upper Ordovician Lashenzhong Formation in Zhuozishan area, Inner Mongolia, in the north of western Ordos Basin, is mainly deposited by turbidity currents concomitant with contour currents as well as internal-waves and internal-tides in deep-water slope and basin floor environment which display typical complex hydrodynamic conditions. Here we studied the deep-water combined-flow sedimentary structures of Lashenzhong Formation in detail based on careful field work, combined with the results of flume experiments and other related case studies in literatures. Several combined-flow sedimentary structures were found in deep-water environment, which include combined-flow-ripple lamination, quasi-planar lamination and small-scale hummocky cross-stratification-like structures. These sedimentary structures can be summarized vertically as 6 sedimentary structure successions: normal graded layer through wave-ripple lamination to combined-flow-ripple lamination (a), quasi-planar lamination through normal graded layer to combined- flow-ripple lamination (b), amphibolous normal graded layer overlaying by quasi-planar lamination (c), quasi-planar lamination through bi-directional cross-lamination to small-scale hummocky cross-stratification-like structures (d), amalgamated small-scale hummocky cross-stratification-like structures enveloped claystone (e) and combined- flow-ripple lamination enveloped claystone (f). The origin of deep-water combined-flow deposits perhaps is the interactions of turbidity currents, contour currents and internal-wave currents according to the sedimentary types and environment in Lashenzhong Formation. Based on the interactions between sedimentary currents and sea floor topography, four sedimentation zones were suggested: turbidity currents restrained zone (succession a and b), strong interaction zone (succession c), internal-wave action zone (succession d) and weak interaction zone (succession e and f). This study will be helpful for the study of interactions of internal-waves and internal-tides with sea floor topography, and related sedimentation zone division in geological records.

No related articles found!
Full text