COALIFICATION AND GRAPHITIZATION OF GRAPTOLITES IN THE ANCHIZONE AND LOWER EPIZONE

In Lower Paleozoic sediments of the South Alpine Carnic Alps (Carinthi a, Austria) fragments of graptolites were used to trace the process of coalification and graphitization in a continuous anchizonal to epizon al metamorphic section. Beginning with the onset of meta-anthracitic c oal ranks, the process of graphitization produces graptolites with the structure of 'coke-like transitional matter'. The path of coalificati on of graptolite fragments is explained by the model of a reflectance indicating surface (RIS). This path resembles the coalification of vit rinite. During the process of coalification the shape of the RIS shows a non-coaxial evolution, starting with a primary biaxia negative geom etry. The oblate graptolite RIS shapes of the Carnic Alps are indicati ve of a metamorphic event with only minor tectonic influence.