徐州—宿州地区滑脱构造的形成机制

    LATE TRIASSIC TRACE FOSSILS AND ICHNOFACIES IN THE BAXI-QOIJE AREA, ZOIGE, SICHUAN

    • 摘要: 徐宿地区平面上存在3个推覆构造带,剖面上有两个不同深度的滑脱层位。推覆构造受到两次构造运动的作用。早期滑脱为后缘推覆,前缘重力扩展、滑动;晚期滑脱为从东向西的推覆。构造变形机制表现为滑脱系统边缘为压剪、内部为挤压。

       

      Abstract: Very abundant and diverse trace fossils have been first discovered in Late Triassic strata in the Baxi Qoijê area, Zoigê, Sichuan. The author describes 22 ichnogenera and 34 ichnospecies. Based on the relative abundance of the ichnogenera in different horizons, 4 ichoassemblages may be distinguished: (1) Helminthopsis Phycosiphon ichnoassemblage, (2) Dendrotichnium Neonereites ichnoassembalge, (3) Paleodictyon ichnoassemblage,and (4) Taenidium Cosmorhaphe ichnoassembalge. The above ichnoassemblages are analogous to Zoophycos and Nereites ichnofaices of Seilacher. In terms of trace fossils, it is suggested that the Late Triassic depositional environment in the area experienced the evolution from the middle lower slope through lower slope to abyssal basin margins.

       

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