Closure temperatures

The table below is not exhaustive but lists the main systems in use today. The closure concept relies on there being a lower temperature limit to effective diffusion of particular atoms in and out of particular mineral lattices. Consequently different minerals (with different lattice structures) behave differently for the diffusion of the same element AND different elements diffuse through the same mineral lattice at different rates.

Closure temperatures
System/mineral Temperature °C

K-Ar (Ar-Ar)

Hornblende 53040
Biotite 28040
Muscovite ~350
K-feldspar ~130 (but very "leaky")
Zircon >750
Sphene >650
Biotite 320
Muscovite 500
Fission tracks
Zircon 175-225
Apatite 10510

n.b. fission tracks are "burn holes" in mineral lattices formed by principally spontaneous fission of uranium. The creation of these tracks follows radioactive decay principles but they represent the ghosts of daughters. However, they are very sensitive to being healed as mineral lattices adjust - even at quite low temperatures. Consequently they give rather low "closure" temperatures (strictly called annealing temperatures).

Closure temperature concept

Dating rocks

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