Earth's dynamic forces (or tectonics) didn't
stand still at the southeastern side of Nain Province, either. Here
the Makkovik Orogen was formed about 1,800 Ma.
Have a look at the heavy, serrated lines on this map. They show
the contacts along which one geologic unit was thrust against the
other. Thus, they denote regions of gigantic thrust faults. The
notches point into the direction whence the thrust came. Actually,
that isn't quite precise to say. The notches are on the side of
those rock formations which were thrust on top of the formations
on the other side. Now, where these lines of thrust, or thrust faults,
meet, there is only one survivor — namely the last one, which
overrides all the imprints which had been left before.
We can see this on the map, where the later Labrador Orogen thrust
cuts across the former New Quebec and Torngat Orogens (or mountain
ranges), as well as the central core of the Rae (Churchill) Province
between them. The thrust of the Labrador Orogen occurred at about
1,700 to 1,650 Ma, or 100 to 150 Ma after the Makkovik thrust. The
reason for the seemingly imprecise figures is that these processes
don't happen in one bang, but proceed over a longish geological
time period. Continents and ocean plates don't move as fast as an
express train, but they are even harder to stop. Some 600 Ma after
the Labrador Orogen had been pushed together another, and much stronger,
push from approximately the same direction created the mighty Grenville
Orogen, reworking the eroded remnants of the Labrador Orogen in
the process.
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