Turning point between green house and ice house earths: investigation of paleothermometry from Cretaceous at Canadian Pacific Coast

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H05213
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 海外学術
• Research Field: Stratigraphy/Paleontology
• Research Institution: Kanazawa University
• Principal Investigator: Hasegawa Takashi 金沢大学, 自然システム学系, 教授(リサーチプロフェッサー) (50272943)
• Co-Investigator(Kenkyū-buntansha): 堀川 恵司 富山大学, 大学院理工学研究部(理学), 准教授 (40467858) ; 山本 正伸 北海道大学, 地球環境科学研究院, 准教授 (60332475) ; 守屋 和佳 早稲田大学, 教育・総合科学学術院, 助手 (60447662) ; 神谷 隆宏 金沢大学, 自然システム学系, 教授 (80194976) ; 森下 知晃 金沢大学, 自然システム学系, 教授 (80334746)
• Research Collaborator: GOTO Akiko (S. Akiko) 金沢大学, 自然システム学系, 博士研究員 ; Haggart James W. カナダ国地質調査所, 主任研究員 ; Crampton James ニュージーランド地質核科学研究所, 主任
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 北東太平洋 / 白亜紀 / カンパニアン / 古水温 / 酸素同位体比 / メタン湧水

Outline of Final Research Achievements

Upper Campanian sequence exposed on a tidal flat around Hornby Island nearby Vancouver Island, British Columbia, Canada, was geologically surveyed. Oxygen and carbon isotopes from the samples obtained from there were analyzed.
A carbonate concretion with 2 m in the major axis was found and identified as a cold methane seep carbonate based on internal structure and carbon isotope signatures. As it was formed just on the sea bottom, the oxygen isotope values were used for paleothermometry of bottom water at depsitional depth (~200 m). Surprizing low paleotemperature as low as 8 ℃ indicates domination of cool water mass that is complarable with deep water over upper bathyal depth of middle latitude North Eastern Pacific. This paleothermometry is important for paleoceanographic reconstruction of North Eastern Pacific during late Campanian.

Free Research Field

地質学・古環境学