Fig. 2

Mass loss and DTG curves for CI chondrites Ivuna and Orgueil, and CI-like Y-82162 and Y-980115. Ivuna and Orgueil show significant mass loss between 200 and 800 °C due to the dehydration and dehydroxylation of abundant phyllosilicates formed during aqueous alteration. However, small amounts of Fe-(oxy)hydroxides (200–400 °C) and carbonates (600–800 °C) are present in the CI chondrites and also contribute to the mass loss in this temperature region. In contrast, Y-82162 and Y-980115 show little mass loss until 700–800 °C. This is due to these meteorites having experienced a thermal metamorphic event(s) that dehydrated the phyllosilicates