Oxygen Isotopes and the Moon-Forming Giant Impact

✍ Scribed by Wiechert, U.

• Book ID: 121347360
• Publisher: American Association for the Advancement of Science
• Year: 2001
• Tongue: English
• Weight: 217 KB
• Volume: 294
• Category: Article
• ISSN: 0036-8075
• DOI: 10.1126/science.1063037

✦ Synopsis

We have determined the abundances of
^16^
O,
^17^
O, and
^18^
O in 31 lunar samples from Apollo missions 11, 12, 15, 16, and 17 using a high-precision laser fluorination technique. All oxygen isotope compositions plot within ±0.016 per mil (2 standard deviations) on a single mass-dependent fractionation line that is identical to the terrestrial fractionation line within uncertainties. This observation is consistent with the Giant Impact model, provided that the proto-Earth and the smaller impactor planet (named Theia) formed from an identical mix of components. The similarity between the proto-Earth and Theia is consistent with formation at about the same heliocentric distance. The three oxygen isotopes (Δ
^17^
O) provide no evidence that isotopic heterogeneity on the Moon was created by lunar impacts.