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USGS CMG InfoBank: San Gabriel Anorthosite

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Comment: 24:21 - 24:56 (00:35)
Source: Annenberg/CPB Resources - Earth Revealed - 14. Intrusive Igneous Rocks
Keywords: "San Gabriel Mountains", differentiation, crystal, anorthosite, "David Sigurdson"

Our transcription: I have another example here also from the San Gabriel Mountains that shows or gives us an idea of how this differentiation may have proceeded.
The crystals grew large.
We can almost imagine the magma surrounding them in this area here and the crystals settling down.
These are single large crystals.
You can tell by their uniform shape and the straight sides, large crystals growing in what was molten rock surrounding it, and these crystals then settled to the bottom of the chamber.
This sample is well over a billion years old, and all of the other known anorthosites are very old as well.

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Page Last Modified: Thu Oct 31 04:26:47 PDT 2013  (chd)