The study of weathering products of meteorites by means of evolved gas analysis

Evolved gas analysis has been used to study the weathering of ordinary chondrites from Roosevelt County (western United States) and from the Sahara (Daraj, western Libya). An interpretation of the evolved gas analysis curves was possible by comparing the data measured on meteorites with the results of analysis on selected Fe minerals as well as chemically synthesised Fe compounds. The amount of H2O released over the temperature range from 25 degrees C to 400 degrees C, and the terrestrial age of the meteorites show a weak correlation. With a higher weathering grade (C,D) that is usually not any longer, Hz is evolved >1300 degrees C, and O-2 is the dominant species in this temperature region. The amount of evolved CO2 and SO2 in different temperature ranges shows significant varieties between specimens from the two desert localities.