MORPHOLOGY AND FOSSILIZATION OF GAOJIASHANIA FROM THE UPPER EDIACARAN DUNFEE MEMBER, DEEP SPRINGS FORMATION, NEVADA, USA

The upper Ediacaran fossil record is characterized by abundant tubular fossils, including the enigmatic Gaojiashania which was first described from the Gaojiashan Lagerstätte of the Dengying Formation of South China. Recent studies have extended the range of Gaojiashania to include the Deep Springs and Wood Canyon formations in Nevada. Here we explore the occurrence of Gaojiashania in the Ediacaran Dunfee Member, Deep Springs Formation, and describe its taphonomic modes. Both body and trace fossil affinities have been proposed for Gaojiashania; we describe morphological and taphonomic evidence indicating a body fossil affinity for the Dunfee specimens. Previous studies have suggested a variety of taphonomic modes for Ediacaran tubular fossils, including association with pyrite, apatite, or clay minerals, as well as preservation as sandstone casts and molds or as carbonaceous compressions. Petrographic, SEM, and EDS data indicate that the Dunfee Gaojiashania specimens are preserved in association with clay minerals, some of which are aluminosilicates, in addition to non-aluminous Mg- and Fe-rich silicate minerals that we interpret as authigenic clays. Insight into the taphonomy of Gaojiashania in the Dunfee Member highlights the wide range of taphonomic modes characterizing Ediacaran fossil assemblages. Elucidation of the taphonomic pathways responsible for fossilization of the Dunfee assemblage provides critical information regarding the diversity, ecology, and environments inhabited by late Ediacaran communities of non-biomineralizing macroorganisms.