Michel Maurette

Carbon-rich micrometeorites and prebiotic synthesis

About 5000 unmelted and well preserved “giant” chondritic micrometeorites with sizes ≈50–200 μ have been extracted from ≈100 tons of antarctica blue ice. They have been unexpectedly well shielded against both terrestrial weathering and frictional heating in the atmosphere. Mineralogical studies indicate that they are all related to primitive “unequilibrated” meteorites (mostly carbonaceous chondrites). About 50% of them are made of friable and porous aggregates of submicron-sized grains, that represent a highly desequilibrated assemblage of minerals, including hydrous silicates and anhydrous clasts, metal oxides and sulfides, and some carbonaceous material related to the broad family of “hydrogenated refractory carbon.” Each carbon-rich micrometeorite might have behaved as a “minicenter” of prebiotic synthesis on the early Earth, through the “in-situ” catalyzed hydrolysis of this carbonaceous material.