豫西济源地区下三叠统陆相碎屑岩中的肯尼亚构造

    The Kinneyia structure in the Lower Triassic nonmarine siliciclastics from Jiyuan area, Western Henan, China

    • 摘要:
      研究目的 肯尼亚构造作为微生物席成因沉积构造(MISS)的典型代表之一,其形成机制引发学界广泛关注和热议。以往该构造多发现于海相或海陆交互相碳酸盐岩—碎屑岩沉积环境中,本文针对豫西济源地区二叠纪—三叠纪之交陆相粉—细砂岩层面上的肯尼亚构造展开研究,旨在补充陆相环境该类构造的地质记录,厘清其成因机制,为进一步理解其地质意义提供新证据。
      研究方法 在详细剖面观察与标本描述的基础上,结合前人研究成果,对该构造的识别标志、形成机制、时间和空间分布特征及古环境指示意义展开讨论。
      研究结果 该构造呈毫米尺度不规则弯曲的波痕形态,波脊的宽度和高度较稳定,以平行分布为主,边缘向外突出成指状,表面披覆富含铁离子的 “泥皮”,常伴生多种 MISS 类型。
      结论 对发育于二叠纪—三叠纪之交陆相环境中的肯尼亚构造的研究,丰富了该构造的沉积环境类型记录,为深入认识古生代—中生代转折期的古环境演变特征提供了新的材料。

       

      Abstract:
      Objective Kinneyia structure, as one of the classic types of microbially induced sedimentary structures (MISS), have attracted extensive attention due to their enigmatic formation mechanisms. Previously documented predominantly in marine to marginal−marine carbonate–clastic successions, this study focuses on the Kinneyia structure specimen developed on bedding surfaces of continental siltstone–fine sandstone across the Permian–Triassic transition in the Jiyuan area, western Henan Province, with the aim of supplementing the geological record of this structure in terrestrial environments and providing new evidence for elucidating its formation mechanism and broader geological significance.
      Methods Based on detailed outcrop section observations and specimen description, combined with previous research findings, the diagnostic features, formation mechanisms, spatio−temporal distribution characteristics, and paleoenvironmental implications of these structures are discussed.
      Results The Kinneyia structure exhibit millimeter−scale, irregularly sinuous ripple−like morphology with relatively stable ridge width and height. The ridges are predominantly parallel−oriented, with margins protruding outward into finger−like extensions. The structure is typically coated with an iron−rich “mudskin” and is commonly associated with various other types of MISS.
      Conclusions This study documents Kinneyia structure developed in continental depositional environments during the Permian–Triassic transition, enriching the known range of sedimentary environments for this structure and offering new insights into paleoenvironmental evolution across the Paleozoic–Mesozoic transition.

       

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