Sedimentary evolution from greenhouse to icehouse of Neoproterozoic and age constraints in the northern Yangtze Craton

Abstract

The late Tonian is a critical period of the global climate transition from greenhouse to icehouse. Systematic analysis of its sedimentary evolution is critical to properly understand the initiation of snowball Earth and the nature of Cryogenian glaciers. However, it is difficult to infer this continuous response to climate change from the perspective of studying the continuous sedimentary sequence and sedimentary evolution, because of the depositional hiatus between the Tonian and Snowball Earth strata in almost all cratons. A unique and continuous Neoproterozoic clastic rock succession developed well in the northern Yangtze Craton. This study analyzes the sedimentology, paleocurrent, major and trace elements, volcanic tuff geochronology, sedimentary sequences, and depositional environment of the Tonian Liantuo Formation to the Cryogenian Gucheng Formation in the Shennongjia area of the northern Yangtze Craton with a focus on sedimentary evolution. UPb zircon radiometric ages from interbedded tuffs obtained by LA-ICP–MS method allow constraining the age of the sedimentary evolution in the northern Yangtze Craton to the late Tonian-early Crygenian. The northern Yangtze Craton began deposition at 763.1 ± 6.2 Ma and the sedimentary environment was dominated by terrestrial fluvial action with a provenance from the continental magmatic arc on the South Qinling Belt. At 752.1 ± 6.5 Ma, a transition from the fluvial-dominated terrestrial system to the transgressive tidal-influenced marine system was coeval with the peak rifting related to the Rodinia breakup. After 722.5 ± 2.1 Ma, the northern Yangtze Craton entered the glaciomarine environment under the influence of a global cooling trend. Our analysis of the sedimentary evolution from the late Tonian to the Sturtian glaciation in the northern Yangtze Craton forced by tectonic- climate deepens our understanding of the paleoenvironment at the beginning of snowball Earth.