'an affective, psychophysiologic and behavioural syndrome developing in reaction to alienation from aboriginal culture under Westernizing influence.'

I have seen the term "coca colanization" used to describe this force, for that is what it is, a "force".

Another metaphor derives from plate tectonics. The dominant [Western] culture 'grinds' out the cultural identity of everything in its path.

It is a grinding down to a cullet, a pulverization of identity. What would you call that, Aorto?

What you have in the end is not a people or an identity, but a cullet. Hence, a culletizing force or influence.

I assume the word you are looking for would come from the studies of plate tectonics. Those grinding, scraping, crushing, pulverizing forces must have a name.

Perhaps "shearing". The shearing away of a cultural identity as in:

cataclastic metamorphism: Takes place in an environment where intense pressure due to shearing is common, as in a major fault zone.