Wildfire in the geological record: Application of Quaternary methods to deep time studies

For hundreds of millions of years wildfire has influenced, and been influenced by, plant evolution, biogeochemical cycling, and climate. Wildfire has even been implicated as one of the causative agents of mass extinctions. The deep time geologic record offers demonstrated, but underdeveloped, potential to advance knowledge on the role of wildfire in the Earth system. Herein, we present and discuss the geologic history of wildfire and methods for its reconstruction. We argue that application of the numeric approaches to wildfire reconstruction often used in Quaternary studies would advance understanding of deep time wildfire. Application of numeric methods increases statistical rigour, with the intent of reducing bias and increasing accuracy. For example, numeric methods offer a means to robustly calibrate the provenance and taphonomy of particles used to reconstruct wildfire, and to quantify uncertainties. Statistical methods should be used to assess the fidelity of new chemical proxies of wildfire, such as the types, amounts, distributions, and isotope signatures of polycyclic aromatic hydrocarbons, to represent source area and fuel type.