Extended Data Fig. 6: Chondrite-normalized REE patterns and REE modelling for various degrees of partial melting of the mantle sources.
From: Ultra-depleted mantle source of basalts from the South Pole–Aitken basin
a, REE modelling using the LMO model from ref. 26. b, REE modelling using the LMO model from ref. 27. c, REE modelling using the LMO model from ref. 28. d, REE modelling using the LMO model from ref. 29. The earliest LMO cumulates that underwent plagioclase separation in each model are taken as the source of the CE6 basalt. Small amounts (0.3–1.0%) of trapped instantaneous residual liquid (TIRL) were added to reproduce the measured source 147Sm/144Nd ratio of 0.262–0.272. As the CE6 basalts have a similar source as Apollo 12 basalts, we adopt the modal mineralogy calculated for Apollo 12 (52% olivine, 23% orthopyroxene, 23% pigeonite, 2% augite; ref. 25). The melts are produced after 0.1–5% partial melting of the mantle sources. Model parameters are listed in Supplementary Tables 6, 7. Detailed description of batch melting and fractional crystallization modeling is provided in the Methods. Normalization values are from ref. 46. Data of the Apollo basalts (A12051 and A15545) are from the mare basalt database of Clive Neal (https://www3.nd.edu/~cneal/Lunar-L/). The modelling results indicate that partial melting of these mantle sources is unable to reproduce the REE composition of the CE6 basalt, particularly the steep heavy-REE pattern. The REE abundances of the CE6 basalt are the average composition of the three fragments (CE6C0000YJYX48501, CE6C0000YJYX48901, and CE6C0000YJYX56201). The error bars are one standard deviation.
