Chronology of Lunar Granite 12033,576: Resetting of Rb-Sr and K-Ca Isochrons
Abstract
Lunar granite 12033,576 is a subsample of the 'large' (approximately 1 g) felsite 12033,507 which was identified from a collection of 4-10 mm particles from the 12033 soil sampled from the north rim of Head Crater in the eastern part of Oceanus Procellarum. Discordant ages of approximately 3.6, approximately 0.8, approximately 3.9, and approximately 2.2 Ga for this lunar granite were obtained, respectively, by the K-Ca, Ar-39/Ar-40, and U-Pb zircon methods in previous studies and by the Rb-Sr method is this study. Assuming the granite crystallized approximately 3.9 Ga ago (zircon age) and was shocked by meteoritic impacts at 0.8 Ga ago (Ar-39-Ar-40 age), the intermediate apparent ages by the Rb-Sr and K-Ca methods can be interpreted as reset by diffusion of the parent and daughter nuclides. The Rb-Sr age is less resistant to resetting than the K-Ca age, but more resistant that the Ar-39/Ar-40 age.
- Publication:
-
Lunar and Planetary Science Conference
- Pub Date:
- March 1993
- Bibcode:
- 1993LPI....24.1295S
- Keywords:
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- Chronology;
- Diffusion;
- Felsite;
- Granite;
- Lunar Craters;
- Lunar Maria;
- Meteorite Collisions;
- Crystallization;
- Hypervelocity Impact;
- Lunar Soil;
- Minerals;
- Nuclides;
- Lunar and Planetary Exploration