Reconstruction of annually-resolving climatic changes during the mid-Cretaceous and early Eocene "greenhouse" periods

2017 Fiscal Year Final Research Report

• Project/Area Number: 16K21095
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Geology; Stratigraphy/Paleontology
• Research Institution: Kochi University (2017); Nagoya University (2016)
• Principal Investigator: Hasegawa Hitoshi 高知大学, 教育研究部自然科学系理学部門, 講師 (80551605)
• Research Collaborator: KUMA Ryusei 名古屋大学, 環境学研究科
• Project Period (FY): 2016-04-01 – 2018-03-31
• Keywords: 年縞 / 白亜紀 / 始新世 / 温室期 / 気候変動 / 湖成層

Outline of Final Research Achievements

In order to reconstruct annual- to orbital-scale paleoclimatic changes in the mid-Cretaceous and early Eocene “greenhouse” periods, the present study examined two of lacustrine varve records of the Shinekhudag Formation in Mongolia and the Green River Formation in Utah, USA.
Based on annually-resolving analyses of lake algal productivity and decadally-resolving analysis of precipitation proxy from the Shinekhudag Formation, we found that solar influence of decadal- to millennial-scale climatic oscillations (ca. 11, 90-125, 210-240, 400-500, 1000-1450, 2000-2300 years cycle) were existed during the mid-Cretaceous “greenhouse” period.
Based on the sedimentary facies analysis and major and minor elemental composition analysis from the Green River Formation, we found that the lake productivity changes were controlled by orbital insolation changes during the early Eocene “greenhouse” period.

Free Research Field

古気候学