Sedimentary environment and geological significance of the Upper Devonian Wutong Formation in Northern Yangtze Plateau, China

Abstract

There is an ongoing debate about the evolution and geological significance of sediments deposited during the Upper Devonian period in the Wutong Formation on the northern margin of Yangtze Plate. Although the deposition of the Wutong Formation is reported to have coincided with the period of global sea-level changes, the sedimentary record has not been clearly interpreted. We utilise the lithofacies, sedimentary petrology and paleogeography of the Wutong Formation to determine the sedimentary environment and its significance in relation to the northern Yangtze Plate and global sea-level fluctuations. Detailed sedimentary petrology shows that the Wutong Formation was deposited in the barrier-free coastal environment, and stratigraphic analyses indicate the presence of two intervals of transgressions. Lithofacies and paleontological records found in the Wutong Formation show that the two transgressive events correspond to periods of global sea-level rise and allow new insights into impacts of the Frasnian global sea-level changes. KEY POINTS Six lithofacies and five lithofacies assemblages can be identified from the Devonian Wutong Formation in the Chaohu area. We find that the Wutong Formation in the Chaohu area is formed in a coastal sedimentary environment. The transgression and regression of the late Devonian in the Chaohu area correspond to the sea-level changes of global Frasnian–Famennian events.