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U-Th-Pb measurements of Luna 20 soil

Geochimica et Cosmochimica Acta

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Abstract

The concentrations of uranium, thorium and lead and the lead isotopic composition of Luna 20 soil were determined. The data indicate that the Luna 20 soil is mainly a mixture of highland anorthosites and low-K basalt, but little KREEP basalt. The U-Th-Pb systematics are discussed in comparison with other lunar soils, especially with Apollo 16 soils which were collected from a 'typical' highland region. The data fit well in the Apollo 16 soil array on a U-Pb evolution diagram, and they exhibit excess lead relative to uranium. This relationship appears to be a characteristic of highland localities. Considering the previous observations of lunar samples, we infer that lead enrichment in the soil relative to uranium occurred between 3.2 and 3.9 b.y. ago and that the soil was disturbed by 'third events' about 2.0 b.y. ago. A lunar evolution model is discussed. ?? 1973.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
U-Th-Pb measurements of Luna 20 soil
Series title:
Geochimica et Cosmochimica Acta
Volume
37
Issue:
4
Year Published:
1973
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1079
Last page:
1086
Number of Pages:
8