Ages of pristine noritic clasts from lunar breccias 15445 and 15455

Rb-Sr, Sm-Nd and Lu-Hf isotope systematics of the lunar Mg-suite: the age of the lunar crust and its relation to the time of Moon formation

“…Several Mg-suite samples have provided younger ages, but only three, 15445,17 [22], 78236 [28] and 74217 [62] have provided ages as old as the older FANs (figure 1). The age determined for 72417 is based on Rb-Sr analyses mostly of different chips from this dunitic clast.…”

“…The age determined for 72417 is based on Rb-Sr analyses mostly of different chips from this dunitic clast. The age of 15445 [22] is based on a Sm-Nd isochron that has highly scattered Rb-Sr systematics that do not support the Sm-Nd age. A second clast (15445,247) from the same sample provides a much younger (4.28 ± 0.03 Ga) Sm-Nd age.…”

“…Finally, exposure of the lunar surface to cosmic ray irradiation produces secondary neutrons that can substantially influence the isotopic composition of samples that have long exposure histories, with important consequences for 146 Sm- 142 Nd and Lu-Hf results [31][32][33][34][35]. (8) 67075 (7) 60025 (6) 67215 (4) Y86032 (5) 60025 (3) 62236 (1) 60016, 3A (2) (a) (9) 73255 (10) 15445,247 (11) 76535 (12) 76355 (13) 76535 (14) 77215 (15) 77215 (16) 78238 (17) 78236 (10) 78236 (18) 15445, 17 (11) FAN range [12]; 2-Marks et al [13]; 3-Borg et al [14]; 4-Norman et al [15]; 5-Nyquist et al [16]; 6-Carlson & Lugmair [17]; 7-Nyquist et al [18]; 8-Alibert et al [19]; 9-Carlson & Lugmair [20]; 10-Carlson & Lugmair [21]; 11-Shih et al [22]; 12-Lugmair et al [23]; 13-Edmunson et al [24]; 14-Borg et al [25]; 15-this study; 16-Nakamura et al [26]; 17-Edmunson et al [27] and 18-Nyquist et al [28]. of lunar highlands rocks.…”

Feldspathic clasts in Yamato-86032: Remnants of the lunar crust with implications for its formation and impact history

“…The low Th abundance in Y-86032 excludes the presence of significant KREEP in the impact melt, but 'Mg-suite' norites and troctolites also have source regions with 147 Sm/ 144 Nd ~0.17 (Shih et al, 1993). Thus, mixing end-members for the IM melt, in addition to components present in the LG breccia, are most likely to be found among rocks that, like KREEP and the Mg-suite, contain an urKREEP component.…”

“New” lunar meteorites: Implications for composition of the global lunar surface, lunar crust, and the bulk Moon

“…Although the era of Mg-suite magmatism was so early (Shih et al 1993) that the lunar interior was probably highly convective compared to its increasingly moribund state during the mare-volcanism era, the circumstances of mantle melting were still probably not entirely controlled by tectonic motions. As with mare volcanism (see above), compositional selection, favoring low-melting, i.e., low-mg, portions of the mantle, may have already been a significant factor.…”