PALEOECOLOGY AND TAPHONOMY OF FOUR SEQUENTIAL EARLY PERMIAN FLORAS AND LANDSCAPES FROM INNER MONGOLIA, CHINA

Four different floras and landscapes are preserved in only 4.32m of geologic section in the Early Permian Shanxi Formation of the Wuda District of Inner Mongolia, northwestern China. These floras represent four different plant communities that followed each other closely in time. The earliest flora was rooted in sandy clay and initiated peat formation that lead to the formation of a lower coal seam. This seam is 230cm thick and overlain by a 66cm thick volcanic tuff that preserves a second distinct flora that grew on the peat at the time of the ash-fall. Standing stems and large plant parts are present. The upper part of the tuff is rooted by a single species of lycopsid (the third flora), again initiating peat formation. On top of the second seam of 120cm thickness rests a roof-shale. It was deposited as mud in a shallow lake, the formation of which was responsible for the cessation of peat deposition. This fourth flora represents the plants growing around the lake on clastic substrate. Four different environments followed each other in this locality over a geologically short time span and each time conditions prevailed to preserve plant macrofossils in four different taphonomic settings. Three of these floras represent peat-forming plant communities of essentially the same time interval. This occurrence demonstrates the great variability of plant communities, landscapes, and taphonomic processes in Early Permian time of the tropical Cathaysian realm.