Dear Aydin,
On reflection, although there are the mini-exceptions, a good general
rule is that basalts come out of the mantle by the partial melting of
lherzolites, and granite originates in the continental crust as melts
and partial melts (the Chappell and White restite model) and simply
redistribute material within the continental crust. The Archaean,
continent-forming TTG (tonalite/trondjemite /granodiorite) question
is another ball-game for which, in my view nobody has provided a
cohesive and satisfactory explanation. Aydin, you have raised some
fascinating and difficult problems. How wonderful is the WWW in which
we can communicate and discuss such things. When I was a student in
the 1950's, we had to write letters that would take days/weeks to
exchange data and ideas, and that was only between two people!!
Best wishes,
John Dewey
--
Please note that my email address has changed to: [log in to unmask]
Prof. John F. Dewey FRS, M.R.I.A., FAA, Mem. Acad. Eur., Mem.
US Nat. Acad. Sci., Distinguished Emeritus Professor University of
California, Emeritus Professor and Supernumerary Fellow, University
College Oxford.
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