Abstract
Water-containing minerals, phyllosilicates, have been found often in extraterrestrial objects such as carbonaceous chondrite or interplanetary dust particles. Their formation mechanisms in the early solar system have been discussed vigorously. Hydrothermal alteration by low-temperature water in the interior of the planetesimals is proposed as the most plausible origin of phyllosilicates. Experiments were demonstrated by using single-stage propellant gun. Recovered samples were observed with TEM and SEM. We found clear evidences of experimental serpentinization of olivine by impact with water based on the investigation of the shock-recovered samples with TEM. Formation of micro-cleaves in olivine crystals by the impact event and subsequent alteration by impact-generated supercritical water promoted rapid serpentinization of olivine. The present results suggest a new model that abundant serpentine might have easily been formed by collisions between icy and silicate objects even in low temperature region of the early solar system. The water in phyllosilicates is widely thought to be a major source of water for some planets. It is highly likely that serpentine formed by shock events in the early solar system might have a dominant carrier of the water on the Earths.
