The Centennial Geologic Map of Vermont (1961; C.G. Doll, W.M. Cady, J.B.
Thompson, & M.P. Billings: Compilers) prepared under the direction of C.G.
Doll, State Geologist, illustrates regionally the transition from north to
south in the state the kinds of metamorphic zoning associated with
intrusion of syntectonic peraluminous granites from depths shallower than
that (i.e. pressure below that) corresponding to the Kya-And-Sil triple
point - where, because of the greater thermal contrast, the successively
lower-grade zones of the aureoles are sharply defined - to those deeper
than, because of the lower thermal contrast - where they aren't. In the
south the extra heat liberated by a cooling pluton is reflected in the
higher grade of metamorphism (kyanite zone) associated with the area of a
post-nappe dome centrally intruded by a pluton, the Black Mountain Granite.
Immediately adjacent to the Black Mountain Granite one can find in
meta-pelites rod-shaped "schimmer aggregate" probably indicative of former
existence as sillimanite that was later metasomatized to fine-grain
muscovite. Outboard of that immediate contact the aluminum silicate is
kyanite. Discussion of the chronological relationship of intrusion and
metamorphism to tectonism, taking advantage of regional variation in the
character of included fabrics - snowball to unrotated - in garnets, is
discussed (p. 119-120) in: Hepburn, J. C., N. J. Trask, J. L. Rosenfeld and
J. B. Thompson Jr. (1984). Bedrock Geology of the Brattleboro Quadrangle,
Vermont-New Hampshire. Agency of Environmental Conservation, Dept. of Water
Resources and Environmental Engineering, Montpelier, Vermont, Vermont
Geological Survey Bull. 32: 162 pp. + colored geologic map and cross
sections.
The above deals only with the phenomenon you are concerned with. The zoning
was described in Barrovian terminology. Facies terminology is also adequate
to describe, but certainly inadequate to expression of process history.
I hope this helps.
Cheers,
John Rosenfeld
>When plutons intrude regions already undergoing regional metamorphism they
>produce a broad aureole of higher grade rocks around the pluton. This sort
>of deep seated contact metamorphism is clearly different from the high
>level, hornfels producing contact metamorphism, but the former is really a
>hybrid between contact and regional. It really ought ot have a name, but
>I've scoured the texts at hand for one anc come up empty handed.
>
>Can anyone out there help? Has a name been suggested? If so do you have
>the original reference? nyone care to suggest a name?
>
>
>Gren Draper
>
>
>**************************************************************************
>
> Grenville Draper
>
> Feb 1999 to June 1999 on sabbatical leave at:
> Area Geodinámica
> Departamento de Geología
> Universidad de Salamanca
> 37008 Salamanca
> SPAIN
>
> Tel (34) - 932-294482
> Fax (34) - 932-294540
>
>
>**************************************************************************
John L. Rosenfeld
Department of Earth and Space Sciences
University of California
Los Angeles, California 90095-1567
Phone: (310) 825-1505 (4 rings>msg)
FAX: (310) 825-2779
E-mail: <[log in to unmask]>
WWW:<http://www.ess.ucla.edu/facpages/rosenfel.html>
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