Ichnofossils and ichnofabrics in the Lower Permian Taiyuan Formation of North China Basin

Thirteen ichnogenera and seventeen ichnospecies were recognised in carbonate rocks from the Lower Permian Taiyuan Formation in North China Basin. Based on the composition, occurrence and diversity of ichnofossils, intensity of bioturbation, lithologic characteristics, especially on the variation of individual size and the filling colour diversities of the Zoophycos burrows, four types of ichnofabrics were recognised, that is (1) epigenic tiering ichnofabric - mainly appeared on or near the bedding plane and formed in restricted bay or lagoon sedimentary environments; (2) shallow tiering ichnofabric - developed less than 15 cm under the bedding plane and occurred in the upper shallow-marine environment; (3) medium tiering ichnofabric - mainly distributed from 15 to 20 cm under the bedding plane and generated in the mid-upper shallow sea (restricted-open platform); (4) deep tiering ichnofabric - distributed from 25 to 30 cm under the bedding plane and occurred in lower shallow sea (open platform) far from shore. Based on ichnological and sedimentological analyses above four types of ichnofabrics, the sedimentary environment model of the ichnofabrics in carbonate rocks from the Taiyuan Formation in North China Basin is proposed in this paper.