Project description
Innovative techniques for the study of Earth's history
The principle of uniformitarianism suggests that Earth has always changed in uniform ways. However, other hypotheses, non-uniformitarian ones for instance, also aim to explain Earth’s evolution. The EU-funded NONUNE project will apply innovative techniques to study the two major events that preceded the principle of uniformitarianism. The project will search for crystallised remnants of the primordial terrestrial magma ocean that explain the early evolution of terrestrial planets. It will also consider mantle dynamics, which studies the evolution of Earth and solid planets under the action of thermal convection. NONUNE project will apply pioneering methods using the tribrid mass-spectrometer Proteus to perform coupled first-principles calculations and petrological experiments and date the global beginning of plate tectonics.
Objective
The project will use a set of innovative techniques to study the two major events that precede classical, uniformitarian geology. We will search for crystallised remnants of the primordial terrestrial magma ocean and examine the consequences of our observations for mantle dynamics. Crystallisation of the dominant lower mantle phase, bridgmanite, imparts a Mg and Si isotopic fingerprint to cumulates and evolving liquid of the magma ocean. Identifying the relicts of these small but distinctive fractionations requires application of our bespoke, high precision analytical protocols. As an integral part of this work, we will undertake coupled first principles calculations and petrological experiments to provide a benchmark documentation of the isotopic fractionations experienced by these two most abundant cation-forming elements in the silicate Earth. We will also date the global onset of plate tectonics from complementary geochemical signatures in two little-studied detrital minerals; Pb enrichment in continental K-feldspars and Mo depletion in rutiles from exhumed fragments of subducted crust. This work uses ground-breaking methodologies made possible by our unique, tribrid (mass-filter:collision-cell:multicollector) mass-spectrometer, Proteus. We will further develop this technology in collaboration with Thermo Fisher to produce a yet more capable next generation instrument. Our tribrid mass-spectrometer allows us to date single, detrital K-feldspars by laser ablation, using Rb-Sr internal isochrons constructed with analyses of host feldspar and sodic perthite exsolutions. Coupled with in situ Pb isotope analysis, we can calculate the U/Pb of the feldspar’s crustal protolith, which diagnostically tracks contributions from subduction.
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Funding Scheme
ERC-ADG - Advanced GrantHost institution
BS8 1QU Bristol
United Kingdom