Study On Ichnofossil Zoophycos And Geomicrobiology Of The Lower Permian Taiyuan Formation, Western Henan And Southeastern Qinshui Basin

The ichnofossil Zoophycos with high abundance are discovered in carbonate rocks from the Lower Permian Taiyuan Formation, which can be divided into four types-Zoophycos with red, off-white, grey and black fillings based on the different colors of burrow fillings. In this paper, geomicrobiology research is based on Zoophycos in four colors from three Taiyuan Formation sections, including Fucheng(southeastern Qinshui basin, Shanxi province), Jiaozuo and Yuzhou(western Henan province). On the basis of detailed field work, microscopic characteristics analysis, observation by SEM and determination by EDS, some progresses obtained as follows:(1) Distribution characteristics of four-color Zoophycos in each limestone bed of three sections are ascertained.(2) The characteristics of grain size, particles type and their abundance, biological assemblages between the burrow fillings and surrounding rocks are observed contrastively.(3) Carbonate micro-shapes found in Zoophycos burrow fillings are observed, their element composition are tested, and the formation of spheroid-like, filiform and rhabditiform micro-shapes are explored. In red fillings, three kinds and seven types of micro-shapes are recognized, which are carbonate spheroids(including spheroid with smooth surface, spheroid with flocculent surface, spheroid with vermiform surface, framboid monomer, and framboid colonies), branched rhabditiform micro-shapes and areatus aggregates. In off-white fillings, two kinds of micro-shapes are recognized, which are spheroids with unshaped surface and fine grain structure, and wormlike micro-shapes preserved in the holes. In grey fillings, only framboid colonies are recognized for the moment. In black fillings, two kinds and ten types of micro-shapes are recognized, which are carbonate spheroids(including spheroid with smooth surface, spheroid with unshaped surface and fine grain structure, spheroid with thorn surface and fine grain structure, framboid monomer, and framboid colonies) and rhabditiform micro-shapes(including rhabditiform in a straight line with smooth surface, rhabditiform with spiral form, rhabditiform with biserial form, rhabditiform with smooth surface and expanding tail end, rhabditiform with thorn surface).(4) Based on the research above, this paper explores the cause of formation and sedimentary environment of Zoophycos four-color fillings. After analyzing, Zoophycos with red fillings deposited in restricted platform or lagoon environment, Zoophycos with off-white fillings deposited in restricted platform or open platform environment, Zoophycos with grey fillings deposited in open platform, platform-inter shoal or restricted platform environment, and Zoophycos with black fillings deposited in open platform, or lagoon environment.