Dating and Isotopic Characterisation for Decarbonisation, Energy, Environment (DICharDEE)

Lead Research Organisation: NERC British Geological Survey
Department Name: NERC Isotope Geosciences Laboratory

Abstract

After a volume of rock forms its chemistry can be altered by geologic events, that move fluids through fractures in the rock. These fluids leach elements from the rocks, can transport them over significant distances, and potentially form enrichments of the elements we need for green technology.

In pursuit of Net Zero carbon emissions, we need to use the properties of the volumes of rock beneath the ground. For example, to efficiently extract green geothermal heat energy, fluids need to efficiently flow through rock fractures. Yet we don't want to store clean energy (e.g. hydrogen) or waste energy products (e.g. CO2 and radioactive waste) deep within the ground if fluids can escape. We also need to better understand the processes and events that concentrate the metals within rocks, that we need for modern society.

To use our subsurface resources appropriately and decarbonise our energy and resource intensive activities, we need to investigate fluid movement through rocks. For example, we need to understand how carbon dioxide and hydrogen move through volumes of rock and over what timescales? Which geological events form key metal resources and how can this knowledge be used to reduce the impact of their exploration? We also need to understand what will occur once humans have interacted with the rock by injecting, extracting and storing resources there.

The spatial scale of many of these rock-fluid reactions requires that we can investigate extremely small chemical variations (isotopes) of specific elements in minerals at spatial scales 10s to 1000s times smaller than a millimetre and do this within the context of the surrounding mineral chemistries and structures. This is much smaller than we can achieve by the typical methods scientists use where rocks are broken-up and the elements of interest are purified from mineral grains in a laboratory. Instead, we need to use lasers to target and sample these extremely small amounts of sample, directly into an instrument (mass spectrometer). However, clashes or 'interferences' then occur between the isotopes we want to analyse and those we do not, because they behave similarly in the mass spectrometer. This limits our potential to answer important questions about the rocks, fluids and alterations.

This bid requests funds to purchase new instrument technology - a collision and reaction cell, multi-collector plasma mass spectrometer (CRC-MC-ICP-MS) with MS/MS capability - that will be coupled to a large-array of existing laser technology already at the host institute.

This instrument uses gasses to react with and purify specific elements, removing the interferences in seconds that would normally takes days in a laboratory, and can decipher mineral reactions at the necessary micro-scale. In this way we can contribute to the UK becoming a world-leader in using the subsurface to achieve Net Zero, whilst still providing the raw materials our economy requires.

Publications

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