摘要:震积岩是地层中记录古地震事件的关键岩石记录,通过震积岩的识别和发育序列的研究有助于认识盆地形成的构造背景和区域大地构造过程。在塔里木盆地西北缘的乌什南部地区新元古界中识别出臼齿构造、微同沉积断裂和液化卷曲变形等古地震引起的软沉积变形构造,发育典型的震积岩(震裂岩和震褶岩)以及震浊积岩、冰碛岩和薄层状钙质泥岩等沉积单元,并在南华系上部形成了深水浊流沉积—冰水混积—地震活动和背景沉积—地震活动等两期震积作用序列。塔里木西北缘南华系震积岩与同时期正断层紧密伴生,共同指示区域构造伸展背景,可能与新元古代罗迪尼亚超大陆裂解、大规模裂谷作用有关。
关键词: 塔里木盆地/
新元古代/
震积岩/
裂谷作用/
超大陆裂解
Abstract:Seismite is the key rock record to record palaeo-seismic events in the strata. The identification and analysis of seismite can help us to understand the tectonic background of sedimentary basin. In the southern Wushen area of NW Tarim Basin, soft sedimentary deformation structures caused by palaeo-earthquakes, such as molar tooth structure, microsynsedimentary fault and liquefaction crimp-deformation, are recognized in the Neoproterozoic in the southern Wushi area in the northwestern margin of the Tarim Basin. Typical sedimentary units, such as seismite(seismicity fissure and seismicity fold), seismicity turbidite, moraine and thin-bedded calcous mudstone, are developed. In the upper part of Nanhua System, there are two periods of seismicity sequence, namely, deep-water turbidity sedimentation, ice-water mixed deposition and seismicity, and background sedimentation and seismicity. The Nanhua seismites are closely associated with contemporaneous sedimentary normal faults in the northwestern margin of Tarim Basin, indicating the regional tectonic extensional setting, which was possibly related to the breakup of the Neoproterozoic Rodinia supercontinent and large-scale rifting.
Key words:Tarim Basin/
Neoproterozoic/
Seismite/
Rifting/
Supercontinent breakup
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