Core-drilling survey of Cretaceous lacustrine deposits in Mongolia: land-ocean linkage during OAE period on tens of thousands year scale

2015 Fiscal Year Final Research Report

• Project/Area Number: 25302011
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 海外学術
• Research Field: Stratigraphy/Paleontology
• Research Institution: Ibaraki University
• Principal Investigator: Ando Hisao 茨城大学, 理学部, 教授 (50176020)
• Co-Investigator(Kenkyū-buntansha): HASEGAWA HITOSHI 名古屋大学, 博物館, 特任准教授 (80551605) ; OHTA TORU 早稲田大学, 教育総合科学学術院, 准教授 (40409610) ; YAMAMOTO MASANOBU 北海道大学, 大学院地球環境科学研究院, 准教授 (60332475) ; HASEBE NORIKO 金沢大学, 環日本海域環境研究センター, 准教授 (60272944) ; HASEGAWA TAKASHI 金沢大学, 自然システム学系, 教授 (50272943)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 白亜紀中期 / モンゴル / 湖成堆積物 / 温室地球 / 古気候 / 古環境変動 / 地球軌道要素 / 湿潤化

Outline of Final Research Achievements

Detailed cyclic stratigraphy of the lacustrine Lower Cretaceous Shinekhudag Formation distributed in Gobi desert, southeast Mongolia, is established through outcrop and three drilled core sections. In terms of radiometric age measurements by FT and U/Pb methods for zircon grains from intercalated tuffaceous layers, the depositional age of the Shinekhudag Formation can be estimated to be during 123-119 Ma (early Aptian).
Several kinds of analyses for annual varve thickness and chemical proxy in mudstone sequences, show climatic and lake-level changes controlled, respectively by solar forcing (11, 88 and 400 yrs) and orbital cycles (20, 100 and 400 kyrs). Therefore, the Shinekhudag lacustrine deposits are interpreted to record the millennial- to orbital-scale paleoclimatic changes in mid-latitude Asia during the Aptian period.

Free Research Field

地質学・古生物学・堆積学