Lunar impactites are mixtures of crustal and impactor materials, preserving geochemical information on the timing and composition of objects striking the Moon over billions of years. Analysis of Apollo samples for highly siderophile element (HSE; Re, Os, Ir, Ru, Pt, Pd) abundances and 187Re-187Os systematics has yielded key information regarding the Moon’s impact history. Apollo samples, however, originate from a limited total lunar surface area (∼18%) and from a geochemically distinct region known as the Procellarum KREEP Terrane (PKT). In contrast, some lunar meteorites sample regions of the Moon away from the PKT. Here we compare HSE abundances and ¹⁸⁷Re–¹⁸⁷Os compositions of lunar impact breccias from non-PKT regions of the Moon, including the meteorite Northwest Africa (NWA) 3163, with Apollo mission impactites. Concentrations of the HSE in non-PKT lunar breccia meteorites lie between 0.001 and 0.01 × CI chondrite values, with measured 187Os/188Os ratios of 0.1216 to 0.1290, predominantly reflecting chondritic impactor signatures. These isotope ratios are generally less radiogenic than those of Apollo impact breccias (187Os/188Os = 0.127–0.141), whose formation ages cluster around ∼3.8 to 3.9 Ga. The inter-elemental HSE ratios of most non-PKT lunar breccias do not consistently match known and likely impactor compositions, instead reflecting modifications during brecciation and melting. Using combined major, trace, and HSE abundances, and 187Os/188Os data, we suggest that this apparent dichotomy arises from the overwhelming imprints of the Imbrium and/or Serenitatis basin-forming impacts at nearside Apollo landing sites. These signatures further bias interpretations of lunar impactor compositions, potentially masking a more representative, temporally continuous chondritic impactor record preserved in non-PKT lunar meteorites.
