Experiments on biomarker preservation

Abstract

Determining how fossils form, and the nature of organic matter that becomes fossilized and which persists through geologic time, are continuing challenges. This is because decay begins immediately after senescence and diagenetic transformations typically continue progressively over millions of years. To this end, in this dissertation, I utilize various biological and geochemical techniques to investigate processes associated with body fossil preservation in Holocene-age concretions that have encapsulated partially-to-fully decomposed fish (capelin - Mallotus villosus). Here I focus on two environments that have produced highly contrasting preservation endmembers that serve as approximate experiments on biomarker preservation. Furthermore, this dissertation includes a series of laboratory modeling experiments to determine the stability of ribonucleic acid (RNA) under early Mars-like conditions and groundtruthing experiments which complement ongoing analyses being conducted aboard the Sample Analysis at Mars (SAM) instrument in Gale Crater. The objective of this dissertation is to investigate the biological and early diagenetic transformation of organic matter within macrofossils and analog experiments to elucidate those processes, biotic or abiotic, which determine subsequent biomarker preservation. This dissertation consists of five research chapters that seek to elucidate: (I) preservation biases, (II) mechanisms of concretion formation, (III) microbial decay communities and the role of the environment on preservation, (IV) the role of metal-catalysis on RNA polymer stability, and (V) the analysis of carbonaceous chondrite meteorites as putative analogs for organics present on Mars today.