Details

Autor(en) / Beteiligte

• Spear, F. S.

Titel

The duration of near-peak metamorphism from diffusion modelling of garnet zoning

Ist Teil von

• Journal of metamorphic geology, 2014-10, Vol.32 (8), p.903-914

Ort / Verlag

Oxford: Blackwell Publishing Ltd

Erscheinungsjahr

2014

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• Garnet in a staurolite–kyanite zone sample from central Vermont displays a bell‐shaped Mn growth zoning with diffusional modification over the outer 100 μm. The diffusion is driven by the prograde net transfer reaction garnet + chlorite = kyanite + biotite as is evidenced by a well‐defined resorption zone on the rim. Analysis of the reaction history and resorbed garnet composition suggests that the peak temperature attained was 620–660 °C. Diffusional modelling of the rim diffusion provides an estimate of the duration of the metamorphic episode over which significant garnet diffusion occurs. The duration is a function of the assumed peak temperature and garnet diffusivities and range from a few hundred thousand years to a few million years. Such short durations require rapid tectonic burial and exhumation of relatively thin tectonic slices.