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Separation of Uranium and Thorium for 230Th-U Dating of Submarine Hydrothermal Sulfides
Published on: May 20, 2019
Uranium-thorium-lead isotope relations in lunar materials
Science (New York, N.Y.)
|January 30, 1970
Summary
Lunar rock and dust samples reveal ancient origins, with ages up to 4.63 billion years. Uranium-lead dating shows concordant results, but a discrepancy between rock and dust ages raises questions about lunar rock genesis.
Area of Science:
- Geochemistry
- Cosmochemistry
- Planetary Science
Background:
- The Sea of Tranquillity, a significant lunar mare, holds crucial clues to the Moon's geological history.
- Understanding the age and formation of lunar materials is vital for reconstructing the early solar system.
Purpose of the Study:
- To determine the lead isotopic compositions and uranium, thorium, and lead concentrations in lunar samples.
- To calculate the apparent ages of lunar rocks and dust to understand their formation timelines.
- To investigate the discrepancy between rock and dust ages and its implications for lunar genesis.
Main Methods:
- Analysis of lead isotopic compositions.
- Measurement of uranium, thorium, and lead concentrations using parts per million (ppm) quantification.
- Calculation of apparent ages using uranium-lead dating.
Main Results:
- Samples from the Sea of Tranquillity exhibit moderately to very radiogenic lead with low initial lead concentrations.
- Uranium and thorium levels range from 0.26-0.88 ppm and 0.87-3.35 ppm, respectively, with Th/U ratios clustering around 3.6.
- Apparent ages for rocks are 4.1-4.2 billion years, while dust and breccia yield ages of 4.60-4.63 billion years.
- Uranium-lead ages are concordant, indicating reliable dating.
Conclusions:
- The lunar surface is an ancient region preserving early solar system events.
- A significant age discrepancy exists between lunar rocks and dust/breccia.
- This age difference poses fundamental questions regarding the processes of rock genesis on the Moon.
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