辽西凌源地区雾迷山组沉积特征与层序地层

依据野外露头等资料,对辽西凌源地区雾迷山组地层进行了详细的沉积相分析,按陆表海潮汐作用将雾迷山组沉积环境分为潮上、潮间和潮下3个相带,建立了雾迷山组的沉积模式。在沉积相研究的基础上,结合层序界面特征,对雾迷山组层序进行了探讨,划分出4个二级层序和22个三级层序,系统地阐述了每个层序的岩石、构造及体系域等特征。层序界面主要以浅水环境(特别是含暴露标志)的沉积物及沉积构造作为识别标志,其中SQ1为Ⅰ型层序,Ⅱ型层序则较为发育,SQ2-SQ22都为Ⅱ型层序。研究区雾迷山期处于浅水陆表海沉积环境,沉积体系域以海进体系域和高水位体系域为主,普遍缺少低水位体系域或陆棚边缘体系域,同时,也不具备形成凝缩层的环境,以最大海泛面沉积物与深海中的凝缩层相对应。

Sedimentary characteristics and sequence stratigraphy of Wumishan Formation in Lingyuan area, western Liaoning Province

Based on outcrop information, the authors made a detailed analysis of stratigraphic sedimentary fades of the Wumishan Formation in Lingyuan area of western Liaoning Province. Depositional environment of Wumishan Formation was divided into supratidal, intertidal and subtidal zones in accordance with the regularity of epicontinental sea tides, and the Wumishan deposition model was established. On the basis of sedimentary fades, combined with sequence characteristics of the interface, the Wumishan sequence was studied, four second- order sequences and twenty-two third-order sequences were recognized, and rock, structure and characteristics of systems tract of each sequence were described systematically. Sequence boundaries were mainly indicated by sediments and sedimentary structures, especially by exposed symptoms, of the shallow water environment. SQ1 is sequence type Ⅰ,Ⅱ-type sequence is more well developed, and SQ2-SQ22 is sequence type Ⅱ. Wumishan deposition in this area belongs to a shallow continental sea sedimentary environment, so that the depositional systems tracts belong mainly to transgressive systems tract and highstand systems tract, commonly with the lack of lowstand systems tract or shelf marginal sysrems tract. It does not have the environment for the formation of condense section either, which makes the maximum flooding surface and deep -sea condense section correspondingly.