Movement of fluids in the Nankai Trough area: Insights from I-129 and halogen distributions along the IODP NanTroSEIZE transect

• Material Type: 文書・図像類
• Title: Movement of fluids in the Nankai Trough area: Insights from I-129 and halogen distributions along the IODP NanTroSEIZE transect
• Author/Editor: TOMARU, Hitoshi; UDO, Fehn
• Author Heading: TOMARU, Hitoshi; UDO, Fehn
• Publication, Distribution, etc.: Elsevier
• Publication Date: 2015-01-15
• Publication Date (W3CDTF): 2015-01-15
• Periodical title: GEOCHIMICA ET COSMOCHIMICA ACTA
• No. or year of volume/issue: 149
• Volume: 149
• Pages: 64-78
• ISSN (Periodical Title): ISSN : 0016-7037
• Text Language Code: eng
• Subject Heading: NanTroSEIZE; Nankai Trough; pore water; iodine; I-129
• Target Audience: 一般
• Note (General): type:text; Halogen concentrations and 129I/I ratios were determined in pore waters from the Nankai Trough subduction system, collected during IODP Expeditions 315, 316, 322, and 333 along the NanTroSEIZE transect. The transect allowed the first direct comparison of iodine results across an active subduction system, from subducting oceanic sediments to the accretionary prism, and the overlying forearc basin. In contrast to the other halogens (Cl and Br) iodine concentrations show large variations within and among the cores at all sites landward of the trough, I concentrations increase rapidly with depth and reach values several orders of magnitude higher than those in seawater, but are only slightly higher than seawater values at the seaward sites. Methane concentrations follow a similar pattern. Host sediments of the fluids are younger than 7 Ma in all the cores, but the ages of iodine in pore waters at the landward sites reach values beyond 30 Ma., In contrast, iodine seaward of the trough is in isotopic equilibrium with the host sediments, resulting in very similar iodine and sediment ages. The distribution of iodine concentrations and ages indicates that iodine at the landward sites has been transported there in aqueous fluids, probably together with methane, from old formations in the upper plate. The specific fluid pathways potentially were influenced by features such as the megasplay fault in the prism or the decollement. The results demonstrate large-scale transport of fluids carrying iodine and other compounds such as methane from old layers in the upper plate to surface locations landward of the Nankai Trough, while separate, but only local hydrologic processes occur in the marine sediments moving toward the trough.
• Access Restrictions: 限定公開
• Related Material (DOI): 10.028
• Is Version Of (URI): URI; http://dx.doi.org/10.1016/j.gca.2014.10.028
• Data Provider (Database): 国立情報学研究所 : 学術機関リポジトリデータベース（IRDB）（機関リポジトリ）; https://irdb.nii.ac.jp
• Original Data Provider (Database): 千葉大学 : 千葉大学学術成果リポジトリ