Disturbance of isotope systematics during experimental shock and thermal metamorphism of a lunar basalt with implications for Martian meteorite chronology

摘要: To better determine the effects of impact-related processes on radiometric chronometers in meteorites, we undertook an isotopic study experimentally shocked and heated samples lunar basalt 10017. Shock experiments at 55 GPa were completed one subsample, a second subsample was evacuated quartz tube 1000 � C for 170 h. A third maintained as control. Samarium-neodymium, Rb-Sr, 238 U- 206 Pb, Pb- 207 Pb analyses mineral fractions (leached unleached), leached whole rocks, complementary acid leachates. Disturbance evaluated through comparison their isochron diagrams with those control sample. The Sm-Nd isotope system least disturbed, Rb-Sr more systems most disturbed by shock annealing. Samples that experienced extended heating demonstrated greater disturbances than samples. In some cases, true crystallization age preserved, others, information degraded or destroyed. no case did generate isochrons linearity while being rotated completely reset. Although our results show neither experimental nor thermal metamorphism alone can account discordant ages represented different Martian postulate may render meteorite susceptible its unshocked counterpart to subsequent disturbance during aqueous alteration. combination these result disparate chronometric preserved meteorites.