TECTONICS AND PALAEOGEOGRAPHY OF SOUTHERN ANHUI DURING THE CARBONIFEROUS

The Carboniferous sediments in southern Anhui were controlled by "three rises and two depressions", synsedimentary faults along the Yangtze River and the Jiangnan fault, The Chaoxian—Lu-jiang and Xuancheng—Jingxian bays were created during the Early Carboniferous, and the differentiation of sedimentary facies belts occurred during the Late Carboniferous. The study of seven time-equivalent sedimentary facies indicates that the sea level changes and distribution of the sedimentary facies belts were closely related to synsedimentary faulting. The above-mentioned bays were of shallow-water type during the early Datangian, but during the late Datangian, the deposition took place only in the Chaoxian—Lujiang bay. Meanwhile, synsedimentary faulting operating intermediate between southern and northern Chaoxian—Lujiang bay was responsible for the differences in the two facies belts: shelf facies in the northern part and tidal flat-lagoon facies in the southern part. By the end of the Carboniferous, structural activities had led to the formation of land, marginal bank and intraplatform shoal.
Two sporo-pollen assemblages have been distinguished in the Tongling peninsula with the aid of biostratigraphic analysis: (1) Retispora lepidophyta vat. minor-Apiculiretusispora nunanensis-Cymbosporites assemblage zone and (2) Dibolisporites distinctus-Auroraspora macra-Scnopfites claviger assemblage zone. This strongly supports the evidence that the Gaolishan Formation in the Tongling region would be ascribed to the early Yanguanian strata. The study of sedimentary facies also shows that there is no marginal facies around the Tongling peninsula, the existence of which may be confirmed by the diachronous cover dolostones.