The duration of near‐peak metamorphism from diffusion modelling of garnet zoning. (28th July 2014)

• Record Type: Journal Article
• Authors: Spear, F. S.
• Is Part Of: Journal of metamorphic geology. Volume 32:Number 8(2014:Oct.)
• Page Start: 903
• Page End: 914
• Publication Date: 2014-07-28
• Subjects: Metamorphism (Geology) -- Periodicals; 552.4
• DOI: 10.1111/jmg.12099
• Languages: English
• ISSNs: 0263-4929

Abstract

<abstract abstract-type="main" id="jmg12099-abs-0001"> <title>Abstract</title> <p>Garnet in a staurolite–kyanite zone sample from central Vermont displays a bell‐shaped Mn growth zoning with diffusional modification over the outer 100 <italic>μ</italic>m. 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.</p> </abstract>