EXPLORING REDOX EVOLUTION PRESERVED IN THE MINERAL RECORD WITH DRAGON

The flow of energy and elements between the geosphere and biosphere can be traced through changing redox chemistry of Earth’s surface. Deep-time trends in the mineral record, including mineral age and elemental composition, reveal a dynamic history of changing redox states and chemical speciation. Additionally, the mineral record contains geochemical signatures that reveal trends in bioavailability of life's critical elements, in particular shifting redox states of metal co-factors used by enzymes across all domains of life. We present a user-friendly exploratory network analysis platform called dragon (Deep-time Redox Analysis of the Geobiology Ontology Network) to facilitate investigation of the expanding redox chemical network preserved in the mineral record throughout Earth's history and beyond. dragon is a browser-based open-source software written in R that, given a user-indicated element or set of focal elements, generates and analyzes interactive bipartite networks of minerals and their constituent elements over a specified range in geologic-time using information from the Mineral Evolution Database (http://rruff.info/evolution/). We apply dragon to investigate the mineral chemistry for iron (Fe) over deep-time and identify the increasing importance of oxygen in the emergence of new Fe minerals from the Paleoarchean to Mesoproterozoic eras, as well as the influence of element electronegativity in Fe mineral formation and electron transfer processes. dragon can be applied to any combination of chemical elements to interrogate the evolving redox chemistry of the mineral record in geologic-time and is freely available from CRAN under a GPL-3 License, with source code and usage instructions hosted at https://github.com/spielmanlab/dragon.