Bob Tacy writes:
"Given Bas Hensen' Geophysical Lab connection, I wouldn't be
surprised if that's where the concept first implanted itself on him".
I would like to point out that in August 1971, when the "concept" (
1971 paper) was submitted, I was yet to set foot on American soil. A
look at the acknowledgements, and references in the paper shows which
influences I thought to be most important in working out how to make
sense of my experiments on a series of bulk compositions. Contrary to
what one might expect, I completed the theory after doing the
experiments, but of course put it in the introduction of my thesis.
The idea to look at the compositional controls on garnet and
cordierite stability, using experimental work in conjunction with the
electron microprobe, came from my supervisor David Green at the
Australian National University, Canberra,in 1967.
The 1971 paper (submitted August 1971) corresponds almost exactly to
chapter 3 ("Theoretical Phase relations in the System
MgO-FeO-Al2O3-SiO2") of my PhD thesis submitted to ANU in November
As for P-X and T-X sections, Ramberg used these in his 1952 book :the
origin of metamorphic and metasomatic rocks !
So if any concepts "implanted themselves" on me,the Geophysical Lab,
with its emphasis on simple (mostly Mg-endmember) systems, did not
have much to do with it. It was in fact not the Americans, but the
Russians which had come pretty close to figuring it all out before
me, as acknowledged in the paper !
That leaves Eric Essene, who was also acknowledged. I learned a lot
from Eric, but he remained highly sceptical of my early (and later !)
attempts at P-X loops, and left ANU well before I finally got on top
of the P-T-X story.
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