Neoproterozoic Seismic Catastrophic Events in Dalongkou Formation of Central Yunnan and Their Geological Significance
滇中中元古界大龙口组地震灾变事件及地质意义

Soft sediment deformation is one of the key indicators identifying the existence of paleo-earthquake. Based on detailed section researches on the Dalongkou Formation in central Yunnan Province, the authors recognized three horizons of earthquake-driven events with abundant soft sediment deformation and liquefied structures such as micro-rumple laminae, soft sediment folding related to liquefied dikes, soft sediment folding related to liquefied beds, interbedded slumping caused by lateral stress, dish/escape structures, liquefied dikes, mushroom- like liquefied beds and hydraulic shattering structures. Besides, molar-tooth structures, whose change in shape, size and dominated orientation of distribution shows similarity with the change of distribution, style of folding and intensity in the above structures, were also found in the three event horizons. Evidence in the modality, special characteristics and properties of event horizons of the soft sediment deformation and molar-tooth structures indi-cates that earthquake was the driven force. All the seismites found were distributed on the east side of the Luoci-Ganzhuang fault, suggesting a close relationship between the basin-controlling fault and some certain de-formation, such as soft-sediment deformation and molar-tooth structure.