An ERC (European Research Council) Synergy grant of €12.8 million over six years (2020-2026) has been awarded to Alexander Sobolev (IsTerre, Grenoble), Stephan Sobolev (GFZ Potsdam, Germany) and John Valley (University of Wisconsin, Madison, USA) to study the evolution of Earth's chemical composition and the underlying physical processes from 4.4 billion years ago to present in a project entitled "Monitoring Earth Evolution through Time" (MEET).
The Earth is a unique planet. No other body in our Solar System has all three phases of water: solid, liquid and gas. And no other planet has plate tectonics. Why is this? And what is the relation of plate tectonics to water? To answer these questions, it is necessary to understand the movement of mass and energy between Earth's deep mantle, surface and back again - which geologists call recycling.
Geological recycling has been responsible for dramatic changes of the Earth's crust and mantle over 4500 million years since the planet's formation, for the continents staying above sea level and for the resources that people are using now. The evolution of Earth has profound implications for questions in other disciplines such as the origin of life and the conditions on exoplanets. In spite of the obvious importance, the evolution of Earth is still poorly understood.
This project will investigate two main questions: How has Earth's chemical composition evolved over time? And what physical processes are responsible for these changes? Previous attempts to understand the early Earth have been stymied because rocks that are archives from this time are either destroyed or altered so that the original chemical information is gone. However, there is a unique possibility to retrieve the chemical tracers most sensitive to changes of Earth's mantle and crust. This information is preserved as melt inclusions in crystals of the refractory minerals olivine and zircon. These are tiny drops of melt that were trapped when the mineral crystallized. They typically measure less than 15 microns and weigh just a few nanograms. The Grenoble and Madison teams will examine millions of grains and study thousands of melt inclusions in olivine and zircon for major, trace and volatile elements and isotopes. This will provide new information on the recycling of chemical elements in the Earth and on formation of its crust since about 4.4 billion years ago to present day.
The Potsdam team will employ physics-based modelling to quantify the exchange and recycling from the deep-Earth to the surface. Stephan Sobolev and his team will use new geochemical and petrological data provided by Grenoble and Madison teams to test new ideas for how the Earth's tectonic processes have evolved over 4400 million years.
In particular, the GFZ team in cooperation with the neighbouring Potsdam Institute for Climate Impact Research PIK will develop a new class of Earth System models that will combine models of mantle convection, plate tectonics, surface erosion and climate to test their hypothesis about important role of surface processes in controlling the emergence and evolution of plate tectonics, recently published in the scientific journal Nature.