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Archive 1 |
The intro to this article bugs me. Anyone any comment on my changing it from
to
Moriori 21:12, August 6, 2005 (UTC)
I think that this article is a very nice start, and have a few comments on how it could be improved to good article status.
Lunokhod 14:41, 24 November 2006 (UTC)
The article states that:
"In general the rocks collected from the Moon are extremely old compared to rocks found on the Earth. The youngest of the rocks is older than the oldest rocks seen on Earth. They range in age from 3.2 billion years from the basalt samples from the lunar mares, up to 4.6 billion years in the highlands. As such they represent samples from a very early period in the formation of the Solar System."
But how on earth (or on the moon) does anyone know the age of the rocks? It's not like anyone can carbon date them or anything. If the article's gonna talk about their age, then it should at least say something about how we know (or at least guess) how old they are!
Further to age of the moon rocks - the highlands! The article purports them to be up to 4.6 billion years old, whilst the wiki on the solar system states that the solar system is 4.567 billion years old (by dating meteorites). I guess that the former figure has suffered from rounding because the rocks cannot be older then the solar system. Has anyone a more accurate figure for this?
Moon rocks are dated using a variety of techniques, most commonly Sm-Nd isochrons (works well for old rocks with plag and pyroxene) and various U-Pb methods. K-Ar and Ar-Ar are commonly used for mare basalts (don't work well on highland rocks). Also zircons are dated using U-Pb methods; zircons are found in the granitoid clasts (rare) and also in the regolith. It is also possible with several of these methods to determine model ages, which date age of separation of the source or sample from a pre-existing uniform source - commonly taken to be same as chondritic meteorites in isotopic composition. The 4.6 Ga age is rounded up from age for condensation of solar nebula based on Pb isotopes. There is a formation interval that can be estimated using short-lived Xe and Al isotopes. This is all discussed in some detail in Brent Dalrymple's book "The Age of the Earth" Geodoc ( talk) 05:00, 16 February 2009 (UTC)
There's a problem with the table showing basalt composition. The row with high titanium content basalt adds up to more than 100 %, which is absurd. Could someone knowledgeable, please, correct that? Thanks. (4:34, 21 March 2009) —Preceding unsigned comment added by 94.253.144.191 ( talk)
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 |
The intro to this article bugs me. Anyone any comment on my changing it from
to
Moriori 21:12, August 6, 2005 (UTC)
I think that this article is a very nice start, and have a few comments on how it could be improved to good article status.
Lunokhod 14:41, 24 November 2006 (UTC)
The article states that:
"In general the rocks collected from the Moon are extremely old compared to rocks found on the Earth. The youngest of the rocks is older than the oldest rocks seen on Earth. They range in age from 3.2 billion years from the basalt samples from the lunar mares, up to 4.6 billion years in the highlands. As such they represent samples from a very early period in the formation of the Solar System."
But how on earth (or on the moon) does anyone know the age of the rocks? It's not like anyone can carbon date them or anything. If the article's gonna talk about their age, then it should at least say something about how we know (or at least guess) how old they are!
Further to age of the moon rocks - the highlands! The article purports them to be up to 4.6 billion years old, whilst the wiki on the solar system states that the solar system is 4.567 billion years old (by dating meteorites). I guess that the former figure has suffered from rounding because the rocks cannot be older then the solar system. Has anyone a more accurate figure for this?
Moon rocks are dated using a variety of techniques, most commonly Sm-Nd isochrons (works well for old rocks with plag and pyroxene) and various U-Pb methods. K-Ar and Ar-Ar are commonly used for mare basalts (don't work well on highland rocks). Also zircons are dated using U-Pb methods; zircons are found in the granitoid clasts (rare) and also in the regolith. It is also possible with several of these methods to determine model ages, which date age of separation of the source or sample from a pre-existing uniform source - commonly taken to be same as chondritic meteorites in isotopic composition. The 4.6 Ga age is rounded up from age for condensation of solar nebula based on Pb isotopes. There is a formation interval that can be estimated using short-lived Xe and Al isotopes. This is all discussed in some detail in Brent Dalrymple's book "The Age of the Earth" Geodoc ( talk) 05:00, 16 February 2009 (UTC)
There's a problem with the table showing basalt composition. The row with high titanium content basalt adds up to more than 100 %, which is absurd. Could someone knowledgeable, please, correct that? Thanks. (4:34, 21 March 2009) —Preceding unsigned comment added by 94.253.144.191 ( talk)