The earliest reference to "regional contact metamorphism" I have come across is
Kays MA (1970) GSA Bulletin 81, 2743-2758.
My primary misgiving about introducing this term is that it may discourage
people from trying to distinguish the separate effects of regional and
contact metamorphism in regions where they overprint one another in space
and time. To illustrate, consider Japan's Ryoke Belt, 1000 km long and 50
km wide, where according to Turner (1981 p.371-2), "the dominant facies is
amphibolite and the characteristic indices of low pressure - andalusite and
cordierite - are widely distributed... The field distribution of [numerous
synmetamorphic granodiorite plutons] correlates broadly but not in precise
detail with the higher grades of regional metamorphism." Sounds like a
prime candidate for "regional contact metamorphism", eh? But mapping and
petrography in a 12x10 km area (Miyake et al 1992, J Mineralogy Petrology
and Economic Geology 87, 475-480) reveals, in splendid fashion, that the
low-P regional metamorphism was followed by an episode of deformation and
then locally overprinted by contact metamorphism at distinctly lower P.
Check it out!
Dugald M. Carmichael Phone/V-mail: 613-533-6182
Geological Sciences, Queen's University FAX: 613-533-6592
Kingston ON K7L3N6 E-mail: [log in to unmask]
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