沉积学报2018，Vol.36Issue(2)：280-290,11.DOI:10.14027/j.issn.1000-0550.2018.025
贺兰山中段长城系黄旗口组地震岩的发现及意义
Discovery and Significance of Seismites in Huangqikou Formation of Changcheng System, Middle Helan Mountain
摘要
Abstract
Through detailed field geological survey, various soft-sediment deformation structures are found in Huan-gqikou Formation in Changcheng System of the middle part of Helan Mountain, including liquefied sand dykes (veins), liquefied hydraulic fracture structures and liquefied breccias, load structures, ball-and-pillow structures, beaded structures,convolution lamination(liquefied curled deformation structures)and step microfaults.Relatively higher compositional maturity and lower texture maturity of quartz sandstones are observed under microscope.Sand-stone grains are mostly subround-round,with various sizes.Muddy sediments mix with clastic particles,or intersperse in sandstones in irregular vein-like form.Micro thrust faults are found cutting laminae under microscope.The sedimen-tary environment of Huangqikou Formation is identified as littoral-neritic sea by analyses of environment and observa-tion of sedimentary structures(such as ridged ripples, small cross-bedding, horizontal bedding and mud cracks). Soft-sediment deformation structures in Huangqikou Formation are most likely formed by seismic events, not gravita-tional load.Four seismic event layers are identified in middle-low part of the first member of Huangqikou Formation. We speculate that at early stage of deposition of Huangqikou Formation,crustal movement was relatively active,then gradually tended to a stable state,appearance of seismites may be related to tectonic setting of extension-rifting of He-lan aulacogen.关键词
贺兰山/长城系/地震岩/软沉积变形构造/黄旗口组Key words
Helan Mountain/Changcheng System/seismites/soft-sediment deformation structures/Huangqikou For-mation分类
天文与地球科学引用本文复制引用
杨宝忠,金巍,曾佐勋,吴海辉..贺兰山中段长城系黄旗口组地震岩的发现及意义[J].沉积学报,2018,36(2):280-290,11.基金项目
中国地质调查局项目(1212011120552) （1212011120552）
地调协作项目(2015010038)China Geological Survey Project,No.1212011120552 （2015010038）
Geological Survey Collaboration Project,No.2015010038 （）
