INVESTIGATING THE INFLUENCE OF THE ORGANIC-WATER INTERFACE ON SILICATE MINERAL AUTHIGENESIS

It is relatively common for some fraction of organic material to be preserved in the sedimentary rock record as disseminated molecular fragments. The survival of wholly coherent tissues from primarily soft-bodied organisms is far more unusual. However, the literature is now well- populated with spectacular examples of soft-tissue preservation ranging from a 2,600 year old human brain to the external molds and casts of the Ediacaran biota that have survived nearly 600 million years. Some of the most exceptional examples of soft tissue preservation are from the Proterozoic-Cambrian transition, however, nearly all modes of fossil preservation during this time are debated. Silicate mineral templates have been implicated as playing a role in several types of soft tissue preservation, including Burgess Shale-type preservation, Bitter Springs-type silicification, as well as with microfossils preserved in phosphate (e.g., Wacey et al., 2014 Scientific Reports). Yet, there is still much debate over whether these mineral coatings form during early stage burial and diagenesis, or later stage metamorphism. This research addresses this question by using in situ fluid cell Atomic Force Microscopy (AFM) to investigate the nucleation and growth of silicate minerals on model biological surfaces. Herein we present results on the deposition of hydrous magnesium silicates on self-assembled monolayers (-OH, -COOH, -CH₃, and –H₂PO₃ terminated surfaces) at ambient conditions.