A Study of Paleoseismic Causes of Neoproterozoic Soft-Sediments Liquefaction Deformation and Slump Composite Structures in Northern Anhui Province
详细信息
- 责任者：Wang Xi (Geological Science and Engineering College ; Shandong University of Science and Technology ; Qingdao 266590 ; China) ; Wang Mingzhen
- 刊名：Acta Geoscientica Sinica
- 出版年：2013
- 卷期：14(3)
- 关键词：震积岩 ; seismites ; 古地震 ; paleoearthquakes ; 安徽 ; Anhui Province
- 页码：p.318-324
- 图表：illus., 30 refs.
- 分类号：0803
- issnNo：ISSN1006-3021
- isbnNo：CN11-3474/P
摘要
Liquefaction deformation-slump composite structures of soft-sediments are developed in the bottom siltstone layer of Neoproterozoic Sishilichangshan Formation in northern Anhui Province. Detailed observation reveals that this section can be divided into three parts. The lower part is a tsunamite layer with no deformation, the middle part is a composite structure which includes liquefaction homogeneous layer, ball-pillow-like layer and slump composite layer, and the upper part is a seismic unconformity layer covered with tsunamite undeformed layer. These parts form a complete earthquake-tsunami seismites sequence, with the middle composite structure being the main cycle layer in this seismites event. Based on an analysis of section characteristics and formation mechanism, the authors found that the section is located in the shallow continental shelf margin of the slope facies. In the paleoseismic multicycle and pulsed tremor, the liquefied homogeneous deformation, load stem subsidence and caprock collapse experienced multiple superimposition, and all these factors ultimately formed a composite structure with soft-sediment deformation features. The powder sandy soft sediments in the shallow continental shelf margin of the slope zone provided the material foundation for tremor deformation energy conversion in Sishilichangshan Formation sediment period. The multicycle pulse of a strong earthquake provided the drivingforce for the soft sediment liquefaction uniform deformation, load stem subsidence, caprock collapse and superimposition.