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Organic geochemical investigation of far-field tsunami deposits of the Kahana Valley,O‘ahu,Hawai‘i |
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| Authors: | Piero Bellanova Mike Frenken Bruce Richmond Jan Schwarzbauer Seanpaul La Selle Frances Griswold Bruce Jaffe Alan Nelson Klaus Reicherter |
| Institution: | 1. Institute for Geology and Geochemistry of Petroleum and Coal, RWTH Aachen University, Lochnerstrasse 4-20, 52056 Aachen, Germany;2. Institute for Geology and Geochemistry of Petroleum and Coal, RWTH Aachen University, Lochnerstrasse 4-20, 52056 Aachen, Germany
Lehr- und Forschungsgebiet Neotektonik und Georisiken, RWTH Aachen University, Lochnerstrasse 4-20, 52056 Aachen, Germany;3. Pacific Coastal and Marine Science Center, U.S. Geological Survey, 2885 Mission Street, Santa Cruz, CA, 95060 USA;4. Pacific Coastal and Marine Science Center, U.S. Geological Survey, 2885 Mission Street, Santa Cruz, CA, 95060 USA Department of Geosciences, University of Massachusetts, Amherst, MA, 01003 USA;5. Geologic Hazards Science Center, U.S. Geological Survey, Golden, CO, 80401 USA;6. Lehr- und Forschungsgebiet Neotektonik und Georisiken, RWTH Aachen University, Lochnerstrasse 4-20, 52056 Aachen, Germany |
| Abstract: | Far-field tsunami deposits observed in the Kahana Valley, O‘ahu, Hawai‘i (USA), were investigated for their organic-geochemical content. During short high-energy events, (tsunamis and storms) organic and chemical components are transported with sediment from marine to terrestrial areas. This study investigates the use of anthropogenic based organic geochemical compounds (such as polycyclic aromatic hydrocarbons, pesticides and organochlorides) as a means to identify tsunami deposits. Samples were processed by solid–liquid extraction and analyzed using gas chromatography–mass spectrometry. A total of 21 anthropogenic marker compounds were identified, of which 11 compounds were selected for detailed analysis. Although the tsunami deposits pre-date industrial activity in Hawai‘i by several hundred years, distinct changes were found in the concentrations of anthropogenic marker compounds between sandy tsunami deposits and the surrounding mud/peat layers, which may help in identifying tsunami deposits within cores. As expected, low overall concentrations of anthropogenic markers and pollutants were observed due to the lack of industrial input-sources and little anthropogenic environmental impact at the study site. This geochemical characterization of tsunami deposits shows that anthropogenic markers have significant potential as another high-resolution, multi-proxy method for identifying tsunamis in the sedimentary record. |
| Keywords: | Anthropogenic marker Hawai‘i Kahana Valley organic geochemistry tsunami |