2012 Fiscal Year Final Research Report

Understanding of "green-house earth" based on environmental reconstruction of the Pliocene warmth

Research Project

Project/Area Number	23810009
Research Category	Grant-in-Aid for Research Activity Start-up
Allocation Type	Single-year Grants
Research Field	Environmental dynamic analysis
Research Institution	University of Toyama
Principal Investigator	HORIKAWA Keiji 富山大学, 大学院・理工学研究部(理学), 助教 (40467858)
Project Period (FY)	2011 – 2012
Keywords	鮮新世 / 温暖化 / ベーリング海 / ネオジム同位体 / 古気候
Research Abstract	In this study, we used deep-sea sediment cores in the Bering Sea obtained by Integrated Ocean Drilling Program （IODP) expedition 323 in 2009. Among the sediment cores we have analyzed, U1341B core was the first continuous sediment samples in the Bering Sea that record the environmental information during the past 4 million-year. We have measured neodymium and lead isotopes of detrital sediments from U1341B core. We found that Alaskan mountain glaciers started to grow from at least 4.1 Ma, when global climate has been considered to be relatively warmer （~3℃) than today, called as the Pliocene warmth, and experienced the significant enlargement at 3.3 Ma and 2.9 Ma. This is the new finding regarding the cryosphere evolution in the Alaska during the Pliocene.