The chlorine isotope fingerprint of the lunar magma ocean

Jeremy W. Boyce, Allan H. Treiman, Yunbin Guan, Chi Ma, John M. Eiler, Juliane Gross, James P. Greenwood, Edward M. Stolper

Research output: Contribution to journalArticlepeer-review

74 Scopus citations

Abstract

The Moon contains chlorine that is isotopically unlike that of any other body yet studied in the Solar System, an observation that has been interpreted to support traditional models of the formation of a nominally hydrogen-free (“dry”) Moon. We have analyzed abundances and isotopic compositions of Cl and H in lunar mare basalts, and find little evidence that anhydrous lava outgassing was important in generating chlorine isotope anomalies, because 37Cl/35Cl ratios are not related to Cl abundance, H abundance, or D/H ratios in a manner consistent with the lava-outgassing hypothesis. Instead, 37Cl/35Cl correlates positively with Cl abundance in apatite, as well as with whole-rock Th abundances and La/Lu ratios, suggesting that the high 37Cl/35Cl in lunar basalts is inherited from urKREEP, the last dregs of the lunar magma ocean. These new data suggest that the high chlorine isotope ratios of lunar basalts result not from the degassing of their lavas but from degassing of the lunar magma ocean early in the Moon’s history. Chlorine isotope variability is therefore an indicator of planetary magma ocean degassing, an important stage in the formation of terrestrial planets.

Original languageEnglish (US)
Article number1500380
JournalScience Advances
Volume1
Issue number8
DOIs
StatePublished - 2015

All Science Journal Classification (ASJC) codes

  • General

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