Abstract:
All dated meteorites have formation ages of 4.4 to 4.6 b.y. (Sears, 1978), except for nine achondrites which crystallized 1.3 b.y. ago (Table 1). These meteorites-shergottites, nakhlites, and chassignites (SNC)-also differ chemically, petrologically, physically, and magnetically from other meteorite types, suggesting a unique origin. We propose, extending previous tentative suggestions (Wasson and Wetherill, 1979; Nyquist et al., 1979a; Walker et al., 1979; McSween and Stolper, 1980), that SNC meteorites are igneous rocks from Mars, and additionally, using the characteristics of SNC meteorites, we speculate on specific events in the history of Mars.
