LINKING SEDIMENTARY TEXTURES TO NEOPROTEROZOIC CLIMATE DYNAMICS

The surface textures of siliciclastic grains, or “microtextures”, reflect the transport history and depositional environment of sedimentary grains, which in turn reflects the climate history during active sediment transport. Recently, Smith (2016) demonstrated that the physical and chemical quartz microtextures found in modern humid, arid, and glacial fluvial systems can serve as paleoclimate indicators. This result, when invoked alongside Walker et al.’s (1981) model of silicate weathering as a long-term control for Earth’s global climate, suggests that global climatic events like the Cryogenian “Snowball Earth” events may leave microtextural signatures in preserved sediments. This study examined the surface microtextures and elemental compositions of lithified Cryogenian and Ediacaran sediments using a combination of petrography, semi-quantitative energy dispersive spectrometry (EDS), and scanning electron microscopy (SEM), in order to explore potential relationships between siliciclastic microtextures and global climate states. During this process, we also tested existing sample preparation methods (acidification, SelFrag, mechanical disaggregation, citrate-bicarbonate-dithionite (CBD)) to assess the types of lithified samples that are amenable to microtextural analysis.