40Ar/39Ar and cosmic ray exposure ages of plagioclase-rich lithic fragments from Apollo 17 regolith, 78461

Earth, Planets and Space

Table 3 Lithologic components that contributed to the trench regolith sample collected at station 8, Apollo 17

Lithologic components	Age (Ga)	Proportions at station 8 (%)	Modal percent plagioclase	Plagioclase composition	Fe/(Fe + Mg) in plagioclase
Mare basalt (92 % high-Ti and 8 % very-low-Ti basalts)
High-Ti (HT)	3.75 ± 0.01 to 3.85 ± 0.04 (1)	25.8	23 (7)	An₈₆-An₈₇ (8)	0.38 to 0.62 (8)
Very-low-Ti (VLT)	3.63 ± 0.04 (2)	2.2	32 (7)	An₉₃-An₉₆ (8)	0.65 to 0.84 (8)
Orange glass (OG)	3.60 ± 0.04 (3) to 3.66 ± 0.04 (4)	12.0	–	–
Highland rocks
Anorthositic norite (AN)	3.75 ± 0.11 to 4.16 ± 0.04 (1)	35.7	60–80 (9)	An₈₅-An₉₈ (9)	0.44 to 1.00 (9)
Noritic breccia (NB)	3.75 ± 0.11 to 4.16 ± 0.04 (1)	15.7	40–60 (9)	An₈₆-An₉₈ (9)	0.19 to 1.00 (9)
Mg-suite (60 % troctolite and 40 % norite)
Mg-suite troctolite (Mg-T)	4.46 ± 0.07 (5) to 4.18 ± 0.07 (6)	4.62	60-85(10)	An₉₄-An₉₇ (11)	0.44 to 1.00 (11)
Mg-suite norite (Mg-N)	4.46 ± 0.07 (5) to 4.18 ± 0.07 (6)	3.08	40-70(10)	An₉₃-An₉₄ (11)	0.31 to 0.54 (11)

Modified after Table 5 of Korotev and Kremser (1992). Data sources are given in parentheses: (1) Tables 5.7 and 5.8 of Stöffler et al. (2006), (2) Zellner et al. (2009), (3) Huneke and Wasserburg (1978), (4) Alexander et al. (1980), (5) Shih et al. (1993), (6) Carlson and Lugmair (1981a), (7) Papike and Vaniman (1978), (8) Table 5.5 of Papike et al. (1991), (9) Table 5.6 and Figure 5.8 of Papike et al. (1991), (10) Table 3 of Wieczorek et al. (2006), (11) Table 5.7 of Papike et al. (1991)