A new study has introduced a new methodology to decipher past temperatures of rocks over unprecedentedly short timescales of high societal importance
The study led by ETH-Zürich in collaboration with international colleagues, including Prof. emeritus Reuven Chen of the School of Physics and Astronomy at the Tel Aviv University
A new study led by ETH-Zürich in collaboration with international colleagues, including Prof. emeritus Reuven Chen of the School of Physics and Astronomy at the Tel Aviv University, has introduced a new methodology to decipher past temperatures of rocks over unprecedentedly short timescales of high societal importance (10,000-100,000 years). The novel method is expected to provide uniquely recent “thermal snapshots” of both surficial and underground rocks, where the current knowledge gap in regard to their recent thermal past often prevents an adequate evaluation of their suitability and sustainability for geothermal energy production, storage of radioactive waste, or utilization as tunnels.
The new method is based on the counter-balancing effects of radiation and heat in natural crystals of feldspar (the most common mineral in the Earth’s crust). Ionising radiation produces free electrons which become trapped in the crystal’s defects and impurities; heat, on the other hand, remobilizes trapped electrons enabling them to return to their original atomic binding sites. In a narrow range where the effects of radiation and heat on free electrons are comparable, the electrons’ concentration in the crystal renders a sensitive thermometer, carrying a time-averaged “memory” of recently experienced temperatures.
The development builds on Prof. Chen’s earlier study carried out during the NASA Apollo mission, which utilised a similar approach to reconstruct the prevailing environmental temperatures on the moon, but until now has not been translated into a routine characterisation of palaeo-temperatures in Earthly materials.