Ichnofabrics And Their Sedimentary Environments In Carbonate Rocks Of The Upper Carboniferous- Lower Permian Taiyuan Formation In Middle South Shanxi Province

The Upper Carboniferous-Lower Permian Taiyuan Formation in middle-south Shanxi Province is a set of coal-bearing formation with marine-terrigenous facies. Abundance ichnofossils are discovered in carbonate rocks of this formation.10 ichnogena and 14 ichnospecies has been recognized and described from the observation of the outcrop sections in Xishan area of Taiyuan city and near Fucheng of Lingchuan county, which include Fodinichnia(10 ichnospecies), Pascichnia(2 ichnospecies) and Domichnia(2 ichnospecies) according to the ethological classification. Based on the composition, occurrence and size of ichnofossils as well as the components and color of burrow filling,and combined with lithologic characteristics of host rock, four types of ichnofabrics and their sedimentary environment model can be established,i.e., Type A, the large-sized Zoophycos —Thalassinoides ichnofabric, which is formed in restricted bay or lagoon sedimentary environment; Type B, the large-sized Zoophycos—Planolites ichnofabric, which is occurred in the upper shallow marine environment between sea level and fair-weather wave base or restricted carbonate platforms environment with shallow and relatively calm water body; Type C, medium-sized Zoophycos — Teichichnus ichnofabric, which is generated in middle shallow sea between fair-weather wave base and storm wave base; Type D, small sized Zoophycos —Chondrites ichnofabric, which is developed in the lower zone of shallow sea below the storm wave base, showing the low oxygen and deeper water environment. The result will provide biologic information in order for the detailed studies on sedimentary environmental evolution of the Taiyuan Formation and can also provide scientific evidence for the study of coal and coalbed gas formation palaeoenvironment in this area.