An oxidation and stable mounting technique for geothermally altered Upper Devonian palynomorphs from western Venezuela

Abstract. Upper Devonian sediments from western Venezuela have yielded palynomorphs that exhibit the palynomorph re-darkening and cracking phenomenon during post-oxidation mounting. A preparation technique has been developed, utilizing a diluted Schultze solution for prolonged periods, that appears not to affect substantially the structure of the palynomorphs, and thus prevents re-darkening. The use of PVA and Petropoxy 154 for mounting ensured the post-oxidative stability of the palynomorphs at room temperature. Conversely, the use of Elvacite 2044 as a mounting medium may cause cracking of the palynomorphs, related to shrinkage during solvent evaporation.