Discovery of the Jurassic seismic liquefaction sandstone pipes in the Yungang Grottoes, Shanxi province and its tectonic significance
Author:
Affiliation:

Clc Number:

Fund Project:

  • Article
  • |
  • Figures
  • |
  • Metrics
  • |
  • Reference
  • |
  • Related
  • |
  • Cited by
  • |
  • Materials
  • |
  • Comments
    Abstract:

    This paper mainly reports on the discovery of more than 20 earthquake- induced liquefaction sandstone pipes in the Jurassic strata in the Yungang Grottoes in the northern margin of the North China Craton. The liquefaction of sand caused by earthquakes is a very common natural phenomenon. The vibration of seismic waves causes the unconsolidated saturated sandy sediments buried in the ground to quickly become fluid and spew to the surface under great pressure to form sand volcanoes or mud volcanoes. In 2008, the Wenchuan M8. 0 Earthquake and the 2012 New Zealand M6.2 Earthquake caused severe liquefaction, forming a series of liquefaction mounds and well- shaped sand volcanoes on the surface. After the ancient earthquakes, liquefied sandy deposits often consolidate in the upwelling channel to form rock pillars or rock pipes, distributed through multiple strata. In recent years, hundreds of large Mesozoic earthquake- induced clastic pipes have been discovered in the Grand Canyon of the United States. In 2018, the authors disovered more than 20 similar meter- scale sandstone pipes with diameters of 15~20 cm and heights of more than 2 m in the Jurassic Yungang Formation in the Yungang Grottoes. Some pipes occur in a beaded shape in the longitudinal direction. Some pipes extend and stretch from bottom to top in irregular branches with distinct phenomena of expansion or contraction and branching or compounding. The internal structure of the sandstone pipe is uniform without any layering signs. Obvious traces of upward traction and dragging in the surrounding mudstones can be observed. These sandstone pipes, which show neither characteristics of silicified wood nor nodules formed by ordinary diagenesis, have no any relation to heavy rain, debris flow, or gravity collapse, but are the remains of earthquake- induced liquefication sandstones pipes which are preserved within strata. Earthquake- induced liquefication sandstones pipes occur mainly 40 m below the 160 Ma tuffaceous micritic carbonate at the top of Jurassic Yungang Formation in the Ningwu- Jingle Basin (Li et al. , 2014). It can be preliminarily concluded that the ancient earthquakes forming these liquefied sandstone pipes occurred in the Late Jurassic between 160.75 Ma and 160 Ma. Formation process of the ancient earthquakes was closely related to te crust movement caused by the Yanshanian movement. These sandstone pipes are the most direct evidence preserved in the strata by the ancient earthquake associated with the Yanshanian movement in the North China Craton.

    Reference
    Related
    Cited by
Get Citation

SU Dechen, YANG Zhanbing, SUN Aiping, QIAO Xiufu.2019. Discovery of the Jurassic seismic liquefaction sandstone pipes in the Yungang Grottoes, Shanxi province and its tectonic significance[J]. Acta Geologica Sinica,93(8):1814-1830

Copy
Share
Article Metrics
  • Abstract:
  • PDF:
  • HTML:
  • Cited by:
History
  • Received:March 24,2019
  • Revised:April 22,2019
  • Adopted:June 03,2019
  • Online: June 03,2019
  • Published: