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ANSMET), with most of the remainder having been discovered by collectors in the desert regions of northern Africa and Oman.Rocks from the Moon have been measured by radiometric dating techniques.Most were photographed prior to collection to record the condition in which they were found.They were placed inside sample bags and then a Special Environmental Sample Container for return to the Earth to protect them from contamination.A combined total of less than one kilogram of material was returned.In 1993, three small fragments from Luna 16, weighing 200 mg, were sold for US$ 442,500.
The ferroan anorthosite suite is the most common group in the highlands, and is inferred to represent plagioclase flotation cumulates of the lunar magma ocean, with interstitial mafic phases formed from trapped interstitial melt or rafted upwards with the more abundant plagioclase framework.
Primary igneous rocks in the lunar highlands compose three distinct groups: the ferroan anorthosite suite, the magnesian suite, and the alkali suite.
Lunar breccias, formed largely by the immense basin-forming impacts, are dominantly composed of highland lithologies because most mare basalts post-date basin formation (and largely fill these impact basins).
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. O'Keefe and others linked lunar granites with tektites found on Earth although many researchers refuted these claims.
Moon rocks on Earth come from three sources: those collected by the US Apollo manned lunar landings from 1969 to 1972; samples returned by three Soviet Luna unmanned probes in the 1970s; and rocks that were ejected naturally from the lunar surface by cratering events and subsequently fell to Earth as lunar meteorites.