Dear Ronan (et al.),
You asked in early October about examples of
contact metam. overprinting regional metam. in
metabasites. Catching up with my e-mail I realise
you've had very few replies, so here's an offering.
The phenomenon is in fact very common in the
Scottish Highlands. Here Precambrian and Lower
Palaeozoic regional metamorphic rocks of the
Dalradian and Moine series, were subjected to
contact metamorphism in the aureoles of diorite-
granite bodies with ages near 400Ma. Thus there
are good examples of greenschist and amphibolite
facies regional metabasites being converted to
amphibole-hornfels and pyroxene-hornfels rocks
with granoblastic textures.
Unfortunately I can't think of recent work (with analyses etc)
that has been done on these rock types. But there
are some classic petrographic references e.g.
Tilley (1924) on 'Contact metamorphism in the
Comrie area' in Quarterley Journal of the
Geological Society vol 80, p. 22-71.
Harker 1939, 'Metamorphism' p. 331 and Fig. 174.
Dept Geology & Geophysics,
University of Edinburgh, King's Buildings,
Edinburgh EH9 3JW,
(FAX 44 131 668 3184)
FAX:  (0)131 668 3184