The preservation of fossil leaves in Cretaceous volcaniclastic rocks from Alexander Island, Antarctica

Summary Leaf compression fossils are abundant within the lower Cretaceous part of the Fossil Bluff Formation in southern Alexander Island, Antarctica. They occur in lacustrine laminated siltstones with a high volcaniclastic component. During zeolite facies metamorphism of the rocks, breakdown of clay minerals, volcanic glass and calcic plagioclase generated new mineral phases. The growth of these minerals was concentrated within and around leaves: finely disseminated oxide of titanium crystallized within the organic material, a thin film of chlorite was precipitated around leaves and silica, calcite and laumontite grew disruptively between leaf cuticles. Despite relatively low levels of organic maturation the structure of the leaf cuticles was destroyed and the only details which survived were those preserved as impressions in the chorite film.