| Autor: |
L. E. Nyquist, B. M. Bansal, C.-Y. Shih, H. Wiesmann |
| Rok vydání: |
1992 |
| Předmět: |
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| Zdroj: |
Earth and Planetary Science Letters. 108:203-215 |
| ISSN: |
0012-821X |
| Popis: |
The paper determines Sm-Nd and Rb-Sr mineral isochrons for an Apollo 17 KREEP (pigeonite) basalt clast from breccia 72275 collected from Boulder 1, Station 2 in the Valley of Taurus-Littrow. Sm-Nd analyses of the basalt yield a precise mineral isochron age of 4.08 +/-0.07 Ga for lambda(Sm-147) = 0.00654/Ga. The concordancy of Sm-Nd and Rb-Sr ages for the basalt suggests that it crystallized about 4.08 Ga ago. Distinct ages and initial Sr isotopic ratios for Apollo 17 KREEP basalts and Apollo 14 and 15 KREEP suggest that these two types of KREEP basalts were not derived from the same source. Apollo 17 KREEP basalts are contemporaneous with some Apollo 14 aluminous mare basalts. The ages and Sr and Nd isotopic data suggest that these two different types of basalts were produced from sources having similar Rb/Sr ratios but different Sm/Nd ratios. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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