鄂西地区震旦系灯影组沉积环境及化石埋藏机制OA

The Ediacara biota are primarily preserved in siliciclastic rocks globally.However,the Sinian Dengying Formation in western Hubei,China,contains abundant Ediacaran metazoan fossils within carbonate rocks,making their preservation mechanism an interdisciplinary focus across sedimentology,stratigraphy,and paleontology.Based on field outcrop observations,thin-section petrography,and compositional analyses of the Dengying Formation in Zigui,western Hubei,this research identifies nine lithofacies types,reconstructs the depositional environment evolution,and explores taphonomy mechanisms by integrating fossil occurrences and mineral distribution patterns.The Dengying Formation exhibits well-developed storm-induced sedimentary structures,with an upward shallowing trend and a regional southwestward deepening pattern.In the study area,Ediacaran metazoan fossils from the Shibantan Member are typically associated with microbial mats and calcarenites in mid-ramp settings(below the fair-weather wave base but above the storm wave base),indicating that rapid burial by distal storm-derived sands in moderate water depths favored fossil preservation.This preservation model aligns closely with classic Ediacaran fossil occurrences in siliciclastic,volcaniclastic,contourite,and turbidite settings worldwide,highlighting that the in-situ rapid burial of fossils triggered by large-scale clastic flows constitutes a universal taphonomy window for the extensive preservation of the Ediacaran biotas.After the storm deposition,microbial mats rapidly colonized sediment surfaces,forming enclosed anoxic environments where microbial activity induced the precipitation of carbonate,phosphate,and silicate minerals,promoting the mineralization of Ediacaran metazoans.This study systematically reveals,for the first time,the synergistic role of microbial mats,storm deposits,and early diagenesis in fossil preservation within carbonate environments,offering novel insights into biotic-environmental coevolution during the Ediacaran Period.