塔里木盆地北缘阿克苏地区震旦系露头层序地层研究

Sequence stratigraphic analysis of the Sinian strata in the Aksu region,Xinjiang

本文对塔里木盆地北缘阿克苏地区磷矿沟震旦系剖面进行了详细的沉积体系研究。结果表明,该剖面主要发育滨岸沉积体系、碎屑岩潮坪沉积体系和碳酸盐潮坪沉积体系,这几种沉积体系的组合反映了震旦纪阿克苏地区由碎屑岩体系向碳酸盐岩体系的演化过程。在野外露头中共识别出4种不同类型的层序界面:(1)海侵上超层序不整合界面;(2)水进侵蚀冲刷面;(3)岩性、岩相转换面;(4)暴露溶蚀面。在识别出层序界面的基础上对震旦系划分出2个二级层序和5个三级层序。第一超层序SS1包含3个三级层序:SQ1、SQ2和SQ3。第二超层序SS2包含2个三级层序组:SQ4和SQ5。

The depositional systems in the Sinian Linkuanggou section in the Aksu region, Xinjiang may fall into the littoral, siliciclastic tidal-fiat and carbonate tidal-flat depositional systems. These depositional systems have recorded the evolution from the siliciclastic rock systems to the carbonate rock systems of the Sinian strata in the Aksu region. Four types of sequence boundaries are recognized for the field outcrops, including the transgressive onlap unconformity, transgressive erosional scour surface, lithologic-lithofacies transitional surface and exposure erosional surface. Two second-order sequences and five third-order sequences are also discriminated for the Sinian strata. The supersequence I represented by the Sugaitebulake Formation comprises the sequences SQ1, SQ2 and SQ3, and the supersequence II represented by the Qigebulake Formation comprises the sequences SQ4 and SQ5. The multiphase tectonic movements are interpreted as the major controlling factor for the formation, development and evolution of the sequence stratigraphy.