Fig. 3: REE modelling of the origin of the CE6 basalt.
From: Ultra-depleted mantle source of basalts from the South Pole–Aitken basin
a, REE modelling of deviation from a garnet-bearing mantle source. The mantle source was assumed to be 78 PCS cumulate + 0.6% TIRL from the LMO model from ref. 29, with 0.8% garnet in the residue. A small degree (1–1.5%) of partial melting with moderate (32–45%) fractional crystallization is required to produce the Apollo 15 basalt 15445, with more extensive (66–75%) fractional crystallization needed to generate the CE6 basalt. b, REE modelling of the deviation from a high-Sm/Yb mantle source. The mantle source was assumed to be 78 PCS cumulate from the LMO model of ref. 27 with a contribution of 0.8% high-Ti component, which is represented by an Apollo 11 high-Ti basalt (10050) from ref. 25. A small degree (0.7–1.0%) of partial melting with moderate (0–40%) fractional crystallization can reproduce the REE pattern of the CE6 basalt. The normalization values are from ref. 46. Because the CE6 basalts may have a similar source to the Apollo 12 basalts, we adopted the modal mineralogy calculated for the Apollo 12 basalts (52% olivine, 23% orthopyroxene, 23% pigeonite, 2% augite)25. The model parameters are listed in Supplementary Tables 6 and 7, and details of the batch melting and fractional crystallization model are provided in the Methods. The REE abundances of the CE6 basalt are the average composition of the three fragments CE6C0000YJYX48501, CE6C0000YJYX48901 and CE6C0000YJYX56201. The error bars are 1 s.d. CI chondrite, Ivuna-type carbonaceous chondrite.
