Increasing terrigenous input into the continental margin seawater during the late Ediacaran, North China

Abstract

The late Ediacaran period encompasses widespread glacial deposits and early animal radiation. The temporal and spatial context of these events is not well established. The possible links between the glacial deposits and late Ediacaran fossils are critical for understanding the co-evolution of early animals and marine environments. This study presents a detailed geochemical reconstruction from the Tuerkeng Formation on the western margin and the Dongpo Formation on the southern margin along the North China Craton (NCC). The two fossiliferous late Ediacaran formations cover a critical interval between the end of the Zhengmuguan-Luoquan glaciation and the occurrence of late Ediacaran tubular fossils (e.g., Shaanxilithes). The two formations' similar and intermediate CIA values indicate moderate weathering under a warm and humid climate. Stratigraphic covariation of water-insoluble elements in samples from Tuerkeng and Dongpo formations suggest a rapid input of terrestrial materials at the beginning of deglaciation, and these terrestrial materials continued to be input into the shallow marine environment along the western and southern margins of NCC during the deposition of the two formations. Accompanied by the continental weathering and erosion of fresh rocks during the postglacial period of late Ediacaran, abundant nutrients as well as the terrigenous materials would be continuously transported into the continental margin seawater, which may ultimately lead to the rise of the Ediacaran biota. Our results provide new insights into paleoenvironment conditions along the continental margin of NCC and highlight the critical role of the postglacial terrigenous input in the evolution of early animals.