Does the moon have a crust like the Earth?
Danilo Anton
It seems that the phase change that happened in
the upper mantle of the Earth, happened with much less frequency in the moon.
There are few lunar granites and they include diorites, monzodiorites, and granophyres. Mineralogically they are composed of quartz,
plagioclase, orthoclase or alkali feldspar, rare mafics (pyroxene), and rare
zircon.
There is very little quartz in the moon surface showing that the original composition of the moon interior is not identical to the one we found on Earth.
The alkali feldspar may have
unusual compositions unlike any terrestrial feldspar, and they are often
Ba-rich. These rocks apparently form by the extreme fractional crystallization
of magnesian suite or alkali suite magmas, although liquid immiscibility may
also play a role. U-Pb date of zircons from these rocks
and from lunar soils have ages of 4.1-4.4 Ga, more or less the same as the magnesian
suite and alkali suite rocks. In the 1960s, NASA researcher John A. O'Keefe and
others linked lunar granites with tektites found on Earth although many
researchers refuted these claims. According to one study, a portion of lunar
sample 12013 has a chemistry that closely resembles javanite tektites found on
Earth.
(partially taken from
wikipedia)
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