Modern and fossil charcoal: aspects of structure and diagenesis |
| |
Authors: | Ilit Cohen-Ofri Lev Weiner Elisabetta Boaretto Genia Mintz Steve Weiner |
| |
Institution: | 1. Department of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel;2. Chemical Research Support Unit, Weizmann Institute of Science, Rehovot 76100, Israel;3. Department of Environmental Science and Energy Research, Radiocarbon Dating Laboratory, Weizmann Institute of Science, Rehovot 76100, Israel |
| |
Abstract: | The structures and compositions of modern and fossil charcoal samples were compared in order to evaluate charcoal degradation processes in archaeological sites. Modern charcoal samples produced in campfires contain two major phases: graphite-like microcrystallites and a non-organized phase. These phases create a mosaic-like structure with differing relative proportions depending on the taxonomic source of the wood used. Fossil charcoal samples (Tel Dor, Israel: 3000 years BP and Kebara Cave, Israel: 40,000 years BP) also contained the graphite-like microcrystallites and the non-organized phases, but were clearly altered compared to modern charcoal. The graphite-like phase of the fossil charcoal has much higher electrical resistivity, and its ESR properties show that it has markedly altered surface electronic states. Infrared spectra show the presence of additional carboxylate groups. Oxidation has therefore altered the structure. This appears to be a “self-humification” process that affects the graphitic component, and probably the non-organized phase as well. |
| |
Keywords: | Charcoal Graphite-like microcrystallites Degradation Humic acid Radiocarbon datings |
本文献已被 ScienceDirect 等数据库收录! |
|