Reconstruction of both salinity and temperature from oxygen isotope of biogenic calcium carbonate

2017 Fiscal Year Final Research Report

• Project/Area Number: 16K13912
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Geochemistry/Cosmochemistry
• Research Institution: The University of Tokyo
• Principal Investigator: SHIRAI Kotaro 東京大学, 大気海洋研究所, 助教 (70463908)
• Co-Investigator(Renkei-kenkyūsha): NAKATSUKA Takeshi 総合地球環境学研究所, 教授 (60242880)
• Project Period (FY): 2016-04-01 – 2018-03-31
• Keywords: 酸素同位体比 / 生物起源炭酸塩 / 古環境指標 / 水温復元 / 二枚貝 / 安定同位体

Outline of Final Research Achievements

Analysis of biogenic calcium carbonate such as bivalve shell and coral skeleton enable to reconstuct past environments . Although oxygen isotopic ratio of biogenic calcium carbonate has been used as a powerful proxy for reconstruction of water temperature at the time of formation, the most important problem was that it can not separate the effect of salinity. In this study, we focused on organic materials contained in a trace amount in the calcium carbonate skeleton, attempting to develop a method for separating the influence of salinity based on oxygen and carbon isotopic ratio. We established an analysis method of carbon isotopic ratio of the organic peel "periostrucm" adhering to the shell of the mussel, evaluated its usefulness as proxy, and confirmed that it is a reliable proxy for riverine imput.

Free Research Field

古環境学，地球化学