Category: metamorphism

Timescales in Geology are rather variable, to say the least. The earth has been around for billions of years so things can go sloooow and still be significant, like the build-up of oxygen produced by life. On the other hand, some things happen quick, like the hour it takes diamond-bearing kimberlite magma to get from… Continue reading Geospeedometry – how fast is metamorphism?

Thermobarometry is the art of inferring Pressure and Temperature conditions by relating the composition of a metamorphic rock to a thermodynamic model, assuming chemical equilibrium was achieved. That’s the single sentence summary, but as usual, things are more complicated if you look in more detail. I’ve discussed elsewhere reasons why chemical equilibrium may not be… Continue reading Metamorphism: open or closed?

‘Ontogeny recapitulates phylogeny’ is such a lovely phrase. It was coined as a biological concept, and is now somewhat discredited. The idea was that as an organism develops as an embryo it passes through stages of growth corresponding to stages of its evolution as an species. My excuse for typing ‘ontogeny recapitulates phylogeny’ (twice!) is… Continue reading Metamorphism: evolving ideas