Lake tectonics in Tibet : uplift of lake shorelines and estimates of lower crustal viscosity

2010 Fiscal Year Final Research Report

• Project/Area Number: 20403014
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 海外学術
• Research Field: Geology
• Research Institution: Nagoya University
• Principal Investigator: WALLIS Simon Nagoya University, 環境学研究科, 准教授 (30263065)
• Co-Investigator(Kenkyū-buntansha): 鷺谷 威 名古屋大学, 環境学研究科, 准教授 (50362299) ; 中村 俊夫 名古屋大学, 年代測定総合研究センター, 教授 (10135387)
• Project Period (FY): 2008 – 2010
• Keywords: チベット / テクトニクス / 地殻の粘性 / 湖段丘

Research Abstract

Models that try to account for the overall morphology and the growth of the Tibetan Plateau commonly assume the presence of a low viscosity layer in the mid crust. To test this model, GPS measurements were made around Lake Nam Co to determine the heights of lake shorelines. In combination with the results of 14C dating, we show that the water level in L. Nam Co has fallen 20 m in the past 10,000 years. If the proposed low viscosity layer does in deed exist, there should be a corresponding uplift of the shorelines as the water level decreases. However, such uplift was not recognized implying that the distribution and presence of any low viscosity layer beneath Tibet needs to be reexamined.

Research Products

• [Journal Article] 14C dating of Tufa deposits around lake Nam Co, Tibet. (2011)
  • Author(s): Wallis, S.R., Nakamura, T., Mori, H., Ozawa, K., Mitsuishi, M., Shirakawa, C.Hayashi, S.
  • Journal Title: Summaries of Researches at Nagoya University Using AMS v.XXII Pages: 174-179
• [Journal Article] Lake shoreline deformation in Tibet and mid-crustal flow. (2010)
  • Author(s): Wallis, S.R., Mori,H., Ozawa,K., Mitsuishi, M.Shirakawa.C.
  • Journal Title: Island Arc 19 Pages: 313-335
  • Peer Reviewed
• [Journal Article] Middle to late Miocene extremely rapid exhumation and thermal equilibrium in the Kung Co Rift, southern Tibet. (2007)
  • Author(s): Lee, J., Hager, C., Wallis, S.R., Stockli, D.F., Whitehouse, M.J., Aoya, M.Wang
  • Journal Title: Tectonics 30, TC doi:10 Pages: 1029/2010TC002745
  • Peer Reviewed
• [Presentation] Deformation of Lake Shorelines and Mid Crustal Flow in Tibet. (2011)
  • Author(s): Wallis S.R., Ozawa,K., Mori,H., Sagiya, T.etc.
  • Organizer: Japan Geophysical Union
  • Place of Presentation: 幕張市
  • Year and Date: 2011-05-27
• [Presentation] チベットNam Co(ナムツォ)地域における湖段丘の年代測定 (2011)
  • Author(s): Wallis, S.R., Nakamura, T., Mori, H., Ozawa, K., など
  • Organizer: 名古屋大学総合年代測定センターシンポジウム
  • Place of Presentation: 名古屋大学
  • Year and Date: 2011-01-14
• [Presentation] 19 Ma ductile extension associated with normal faulting in the Kung Co area, southern Tibet. (2010)
  • Author(s): Mitsuishi, M., Wallis, S.R., Aoya, M., Lee, J., Whitehouse, M.
  • Organizer: HKT (Himalaya Karakorum Tibet) 25
  • Place of Presentation: San Francisco
  • Year and Date: 2010-06-09
• [Presentation] Cenozoic emplacement age of the Kangmar granite in south Tibet. (2010)
  • Author(s): Shirakawa, C., Wallis, S.R., Kitajima, K., Sano, Y.
  • Organizer: HKT (Himalaya Karakorum Tibet) 25
  • Place of Presentation: San Francisco
  • Year and Date: 2010-06-09
• [Remarks] ホームページ等