Formation and relative ages of maskelynite and carbonate in ALH84001

摘要: The morphology and stoichiometry of feldspathic glass in the Martian meteorite ALH84001 indicates it is maskelynite (a diaplectic glass) rather than a flowed glass, although this was heterogeneously affected by tertiary set processes. An impact event with shock pressures excess 31 GPa needed to convert original plagioclase (An36Ab60Or4) maskelynite. Carbonate intimately associated maskelynite, carbonate’s radiating crystalline fabric globular forms suggest produced after converted Textures also carbonate at expense dissolution-precipitation reaction that involved carbonic fluid. This fluid system tentatively estimated have been active for least few years temperatures <300°C, based on dissolution rates mildly strongly alkaline hydrothermal systems (which only analogue currently available). does not need be mitigated microbial life. Neither are bacteria produce textures carbonate, which may instead reflect kinetic phenomena crystal nucleation growth. Because younger has previously shown last degassed 3.92 ± 0.04 Ga (Turner et al., 1997). However, specific age remains unknown.