Outcrop at the shore line of Badplats Blankaholm. Approach via Blanka and Blankaholm. Excellent and interesting
outcrop, but be careful, cliffs are steep!
The exposed rocks at this location show a light gray to light brown matrix with reddish to orange colored
veins (cf. fig. 4.19a-c). These rocks are interpreted as migmatites from former volcano clastic sediments
of the Västervik Formation.
A close look is needed to recover the complex development of these migmatites. The reddish colored
veins are considered to represent the neosome (leucosome) though its color is darker than the one of
the matrix. The veins are surrounded by a fine rim of dark color, the melanosome. Here the questions,
how a red colored neosome can emerge from a host rock of this light color, is obvious. Parts of the
neosome was probably build on in-situ melting. It is assumed that some material must have come from
outside, e.g. a granite in the immediate vicinity, that intruded the metasediments concordant to their layering.
However, these rocks contain another special characteristic. On observation one can detect xenoliths of flecky
gneisses within the migmatites (cf. fig. 4.19a-c). They are considered as remnants of former contact metamorphism.
On these features a sequence for the development of these rock be: A volcano clastic sediment experienced
contact metamorphism due to an intruding granite in the vicinity which led to the formation of flecky gneisses
(cf. loc. 18). Then, however the surrounding of the former flecky gneisses was heated further on which yielded
in migmatization and development of what they are today.