This study monitors regional changes in the
crystallinity of carbonaceous matter (CM) by applying
Micro-Raman spectroscopy to a total of 214 metasediment
samples (largely so-called Bu¨ndnerschiefer) dominantly
metamorphosed under blueschist- to amphibolite-facies
conditions. They were collected within the northeastern
margin of the Lepontine dome and easterly adjacent areas
of the Swiss Central Alps. Three-dimensional mapping of
isotemperature contours in map and profile views shows
that the isotemperature contours associated with the Miocene
Barrow-type Lepontine metamorphic event cut across
refolded nappe contacts, both along and across strike
within the northeastern margin of the Lepontine dome and
adjacent areas. Further to the northeast, the isotemperature
contours reflect temperatures reached during the Late
Eocene subduction-related blueschist-facies event and/or
during subsequent near-isothermal decompression; these
contours appear folded by younger, large-scale post-nappestacking
folds. A substantial jump in the recorded maximum
temperatures across the tectonic contact between the
frontal Adula nappe complex and surrounding metasediments
indicates that this contact accommodated differential
tectonic movement of the Adula nappe with respect to the
enveloping Bu¨ndnerschiefer after maximum temperatures
were reached within the northern Adula nappe, i.e. after
Late Eocene time.