Spectacular New Sidewalks in Siem Reap with mariotitic cavities

Siem Reap has 98km of new roads  and new sidewalks much of which has been paved with interesting felsic intrusive rocks from quarries in Shandong Province in China.  The composition ranges from granodiorite to tonalite and is locally granophyric and pegmatitic.  The intrusive consists dominantly of plagioclase, quartz, pyroxene and hornblende. Ovoid structures known as Miarolitic Cavities are evident in the sidewalks to the observant and indicates that the parental magma was hydrous. While no cavities have been observed in the sidewalks of Siem Reap it is quite possible that miarolitic cavities which retained cavities were not processed into saleable dimension stone. When the location of the quarry in Shandon Province is identified maybe a field trip is warranted.

The term miarolitic comes from the Italian miarole in reference to the mineral-rich pegmatite region of Baveno and Cuasso al Monte in northern Italy.

There are two types of miarolitic cavities observed. One has a coarsely pegmatitic core of intergrown quartz and plagioclase surrounded by a conspicuous pyroxene rim and the core may contain coarse tourmaline. The second type has a conspicuous leucocratic zone and a complex core of intergrown quartz and tourmaline.  Where there are sufficient sections these features have a  long axis that  that is maybe 5 times the sectional axis.

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