Georg-August-Universität Göttingen, Geowissenschaftliches Zentrum, Abteilung Isotopengeologie, Goldschmidtstraße 1, 37073 Göttingen, Germany. Universität zu Köln, Institut für Geologie und Mineralogie, Zülpicher Straße 49a, 50674 Köln, Germany.
Georg-August-Universität Göttingen, Geowissenschaftliches Zentrum, Abteilung Isotopengeologie, Goldschmidtstraße 1, 37073 Göttingen, Germany.
Science. 2014 Jun 6;344(6188):1146-50. doi: 10.1126/science.1251117.
The Moon was probably formed by a catastrophic collision of the proto-Earth with a planetesimal named Theia. Most numerical models of this collision imply a higher portion of Theia in the Moon than in Earth. Because of the isotope heterogeneity among solar system bodies, the isotopic composition of Earth and the Moon should thus be distinct. So far, however, all attempts to identify the isotopic component of Theia in lunar rocks have failed. Our triple oxygen isotope data reveal a 12 ± 3 parts per million difference in Δ(17)O between Earth and the Moon, which supports the giant impact hypothesis of Moon formation. We also show that enstatite chondrites and Earth have different Δ(17)O values, and we speculate on an enstatite chondrite-like composition of Theia. The observed small compositional difference could alternatively be explained by a carbonaceous chondrite-dominated late veneer.
月球可能是由原始地球与名为忒亚的微行星灾难性碰撞形成的。这一碰撞的大多数数值模型都表明，月球中忒亚的比例高于地球。由于太阳系天体之间的同位素异质性，地球和月球的同位素组成应该是不同的。然而，迄今为止，所有试图在月球岩石中识别忒亚同位素成分的尝试都失败了。我们的三重氧同位素数据显示，地球和月球之间的Δ(17)O 存在 12±3 百万分比的差异，这支持了月球形成的大碰撞假说。我们还表明顽辉石球粒陨石和地球具有不同的Δ(17)O 值，并且我们推测忒亚具有类似顽辉石球粒陨石的组成。观测到的小成分差异也可以用富含碳质球粒陨石的晚期覆盖层来解释。
