| タイトル | Evolution of mare basalts - The complexity of the U-Th-Pb system |
| 著者（英） | Unruh, D. M.; Tatsumoto, M. |
| 著者所属（英） | Geological Survey |
| 発行日 | 1977-01-01 |
| 言語 | eng |
| 内容記述 | An attempt has been made to gain more insight into mare-basalt evolution by performing a very detailed leaching and mineral-separation U-Th-Pb systematics study on mare basalt 15085. It is found that about 20-50% of the U, Th, and Pb reside on the grain boundaries or in the mesostasis and that the Pb-207/Pb-206 ratios of the grain boundaries and crystal interiors are distinctly different. These distinct trends appear to represent either continuous or episodic postcrystallizational disturbances to the U-Th-Pb system of this rock. Using U and Pb partition coefficients, it is concluded that existing two- and three-stage U-Pb evolution models do not accurately describe mare-basalt genesis. An alternative two-stage + KREEP mixing model is proposed as a simple approximation to U-Pb evolution in lunar rocks. Most Rb-Sr and Sm-Nd data are compatible with this model. |
| NASA分類 | LUNAR AND PLANETARY EXPLORATION |
| レポートNO | 78A41656 |
| 権利 | Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/432183 |
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