Gleason J D, Kring D A, Hill D H, Boynton W V
Lunar and Planetary Laboratory, University of Arizona, Tucson 85721, USA.
Geochim Cosmochim Acta. 1997 Aug;61(16):3503-12. doi: 10.1016/s0016-7037(97)00173-7.
New petrologic and bulk geochemical data for the SNC-related (Martian) meteorite ALH84001 suggest a relatively simple igneous history overprinted by complex shock and hydrothermal processes. ALH84001 is an igneous orthopyroxene cumulate containing penetrative shock deformation textures and a few percent secondary extraterrestrial carbonates. Rare earth element (REE) patterns for several splits of the meteorite reveal substantial heterogeneity in REE abundances and significant fractionation of the REEs between crushed and uncrushed domains within the meteorite. Complex zoning in carbonates indicates nonequilibrium processes were involved in their formation, suggesting that CO2-rich fluids of variable composition infiltrated the rock while on Mars. We interpret petrographic textures to be consistent with an inorganic origin for the carbonate involving dissolution-replacement reactions between CO2-charged fluids and feldspathic glass in the meteorite. Carbonate formation clearly postdated processes that last redistributed the REE in the meteorite.
与SNC相关（火星）的陨石ALH84001的新岩石学和整体地球化学数据表明，其相对简单的火成岩历史被复杂的冲击和热液过程叠加。ALH84001是一种火成正辉石堆积岩，含有贯穿性的冲击变形纹理和百分之几的次生外星碳酸盐。该陨石几个碎块的稀土元素（REE）模式显示出REE丰度存在显著的不均匀性，并且陨石内破碎和未破碎区域之间的REE有明显分馏。碳酸盐中的复杂分带表明其形成过程涉及非平衡过程，这表明成分可变的富含CO₂的流体在火星上时渗入了岩石。我们将岩石结构解释为与碳酸盐的无机成因一致，这涉及到陨石中含CO₂流体与长石玻璃之间的溶解-置换反应。碳酸盐的形成显然晚于上次在陨石中重新分配REE的过程。
