I think this discussion on the definition and origin of the word nappe is
very enlightening. In particular, it reminds us that, for the early
Alpine geoscientists, the allochthonous (or "para-allochthonous") nature
of many of the rock sequences was clear, while the tectonic mechanism was
not, and discussions continued (and continue) over the contribution from
large scale (km to 10's km) folding versus thrusting. There is perhaps a
note of caution (or "reservation") in here for all of us who are modern
day "thrusters" (as John Ramsay so wonderfully termed) as we geometrically
tightly interpret and line-balance orogens (even down to 10's of km
depth!) from around the globe.
Mike (Andy) Edwards
**********************************
M. A. Edwards ([log in to unmask])
Structural Processes Group
Dept. of Geological Sciences
University of Vienna
Althanstrasse 14
Vienna A-1090
Austria
office +43-1-4277-53446
lab +43-676-620-1998
fax +43-1-4277-9534
http://mailbox.univie.ac.at/Michael.Edwards/
Structural Processes Group web page...
http://www.univie.ac.at/Geologie/strucproc/
|