PROCRUSTEAN S CIENCE: I NDIGENOUS S IDEROPHILES IN THE LUNAR H IGHLANDS, A CCORDING TO DELANO A ND R INGWOOD

摘要: The best estimate of indigenous lunar siderophiles comes from 29 pristine rocks, characterized by low siderophile abundances, plutonic textures, and high age. Delano Ringwood's blanket rejection these on the contention that they are impact melts, is not justified petrologic evidence. Contrary to their claims, gold in highland breccias largely meteoritic unaffected fumarolic volcanism, as shown its correlation with Ir noncorrelation fuma- rotic T1 (r = 0.896 0.272). approach, involving subtraction an H- chondrite component breccias, ignores variation Ir/Au ratios modern ancient meteorites, hence leads spurious excesses Au, Ni, volatiles, some cases physically meaningless, negative residuais. Their "excess volatiles' crust relative mare basalts disappear when composition based rocks rather than under- corrected breccias. claims Ringwood, Ni/Co trend Apollo 16 samples cannot be explained rich Ni (150-200ppm) Co (30-45 ppm); mixing lines show much lower contents required (e.g., - 7 ppm each). Chondrites essentially parallel fractionation trends for siderophile-element Re/Ir, Au/Ir, Ni/Ir, Ni/Pd, Os/Ir. Because chondritic were established solar nebula, it appears also reflect nebular processes, have been modified planetary processes. Properly derived abundances highlands large, systematic depletions terrestrial oceanic tholeiites, following factors: Ge 270, Re 230, Sb 170, Zn 150, Au 60, T150, Ag 48, 42, Se 12. It would seem resemblance Earth's mantle quite 'striking' claimed Ringwood.