Investigating Palaeoclimate Using Spherules in the Geological Column

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The geological record holds a record of the past climate conditions on Earth. The evidence in the rocksprovides the only reliable baseline by which models of extreme climate behaviour can be tested. Without thisevidenceclimate models cannot be extrapolated far beyond modern datasets with confidence. There are many forms that climatic indicators take in the geological record, but mostare indirect measures, requiring complex models and extrapolations to provide reliable constraints for climate models. This project proposes a new and novel form of palaeoenvironment indicator that could revolutionise the way we examine the ancient past. Hidden within rocks are tiny spherules, tens to hundreds of microns in diameter, that have been the subject of little study before now. Some of these particles are extraterrestrial dust, which equilibrated with the atmosphere during flash heating during atmospheric entry, and provide a direct samples of atmospheric gas. Some are lightning strike particulates, and record the prevalence of extreme climate events. Others are the products of forest fires, produced by the fusion of mineral inclusions and air-borne dust trapped within plant material and record the global occurrence of natural fires, directly linked to climate.Some are volcanic in originandrecord the global activity of volcanoes, which in pre-industrial epochs were major forcesof the climate system.Unlike proximal volcanic deposits they are widely distributed.Finally, a small number of particles may also be the result of the impact of larger extraterrestrial object with the Earth, generating extreme short-period events effecting global climate. To date there have been no systematic studies of the chemical, mineralogical and isotopic properties of small spherules within sedimentary rocks. Our groups previous research has, however, shown they are abundant and recoverable. The objective of this researchis to produce the primary criteria by which these materials can be related to source, generating the primary reference for this new field of study.