Characteristics of Ordovician sedimentary evolution in Hunan Province

Abstract: Based on field survey, laboratory analysis of sedimentary strata and summarization of previous research results in Hunan Province, the authors divided the Ordovician tectonic and sedimentary evolution into four stages, i.e., rimmed carbonate platform-shelf-deep water basin in the Early Ordovician, carbonate ramp-shelf-deep basin in the Middle Ordovician, carbonate ramp-shelf-deep water basin-shelf margin at the early age of Late Ordovician, and confined shallow marine-deep water basin-shelf margin in the late period of the Late Ordovician. The northwestern Hunan in Yangtze craton experienced the evolution from the rimmed carbonate platform to carbonate ramp, and finally became a confined shallow sea, with the black shale gradually replacing carbonates in lithology. The central and southern Hunan located at the edge of the craton and the Cathaysia Block was always in a clastic shallow marine environment, and the center of the basin migrated constantly from southeast to northwest.