Lu-Hf and Sm-Nd evolution in lunar mare basalts

Journal Article · Wed Feb 15 04:00:00 EST 1984 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB089iS02p0B459· OSTI ID:6741932

Unruh, D M; Stille, P; Patchett, P J; Tatsumoto, M

Lu-Hf and Sm-Nd data for mare basalts combined with Rb-Sr and total REE data taken from the literature suggest that the mare basalts were derived by small (< or =10%) degrees of partial melting of cumulate sources, but that the magma ocean from which these sources formed was light REE and Hf-enriched. Calculated source compositions range fromm lherzolite to olivine websterite. Nonmodal melting of small amounts of ilmenite (< or =3%) in the sources seems to be required by the Lu/Hf data. A comparison of the Hf and Nd isotopic characteristics between the mare basalts and terrestrial oceanic basalts reveals that the epsilonHf/epsilonNd ratios of low-Ti mare basalts are much higher than in terrestrial oceanic basalts. The results are qualitatively consistent with the hypothesis that terrestrial basalt sources are partial melt residues whereas mare basalt sources are cumulates. Alternatively, the results may imply that the terrestrial mantle has evolved in two (or more) stages of evolution, and that the net effect was depletion of the mantle during the first approx.1-3 b.y. followed by enrichment during the last 1-2 b.y.; or simply that there is a difference in Lu-Hf crystal-liquid partitioning (relative to Sm-Nd) between the lunar and terrestrial mantles.

• Research Organization: U.S. Geological Survey
• OSTI ID: 6741932
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 89:S1; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics &amp; Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BASALT
ELEMENTS
FRACTIONATION
GEOLOGY
HAFNIUM
IGNEOUS ROCKS
LUNAR MATERIALS
LUTETIUM
MAGMA
MATERIALS
MELTING
METALS
MOON
NEODYMIUM
PETROLOGY
PHASE TRANSFORMATIONS
RARE EARTHS
ROCKS
SAMARIUM
SATELLITES
SEPARATION PROCESSES
TRANSITION ELEMENTS
VOLCANIC ROCKS