双壳类生物壳体的clumped同位素在渤海湾河口海岸地区水温重建中的应用

项目名称： 双壳类生物壳体的clumped同位素在渤海湾河口海岸地区水温重建中的应用

项目编号： No.41503008

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 天文学、地球科学

项目作者： 胡斌

作者单位： 中国地质科学院矿产资源研究所

项目金额： 21万元

中文摘要： 海水古温度可以反映过去的气候和水文变化，是全球气候变化的重要研究内容。海洋双壳类壳体是一种理想的高分辨率古海洋信息载体，记录了年际，季节甚至月分辨率的水体环境变化。传统的壳体Sr/Ca，Mg/Ca温度计存在动力学因素的影响，而氧同位素温度计则受到古海水氧同位素组成和变化的影响，在示踪海水古温度时受到限制，在海岸带和河口等地区尤为突出。碳酸盐的clumped同位素是一种新的单相温度计，与环境流体的同位素组成无关。本申请拟采用双路进样气体源同位素比质谱法建立可靠的碳酸盐clumped同位素分析和校正方法；测量渤海湾地区有生长环境记录的现生牡蛎壳体的Δ47，建立Δ47与水温变化的函数关系；测量渤海湾地区全新世埋藏牡蛎壳体具有季节指示意义的微生长层的Δ47，尝试开展季节分辨率的表层古水温重建，结合氧同位素温度计计算同期海水的氧同位素组成，为重建古海水温度及古气候的短尺度振荡和季节变化提供新的思路。

中文关键词： clumped同位素；古温度；双壳类壳体；河口海岸地区；高分辨率

英文摘要： The paleotemperature of the seawater, which could reflect the climate and hydrological change in the geological past, takes an important role in the study of global climate change. The shell of marine bivalve is an ideal high-resolution archive of the past ocean and it can record the annual, seasonal and even monthly change of the aquatic environment. However, the Sr/Ca and Mg/Ca thermometry of bivalve shell are affected by kinetic effects, and the application of oxygen isotope thermometry is limited especially in the coastal and estuarine regions for the difficulty in constraining the influence of the isotopic composition of ancient seawater and its variation. The clumped isotope technique is a newly developed homogeneous thermometry. It is independent from the isotopic composition of the ambient fluid from which the carbonate is precipitated. In this study, we will establish the methodology for clumped isotope analysis and data correction using dual-inlet gas-source isotope ratio mass spectrometry, measure the Δ47 of modern oyster shells grown at monitored conditions in Bohai Bay, and calibrate the Δ47 proxy against the calcification temperature. Then we will measure the Δ47 of the ligamental increments that indicate seasonality of buried Holocene oyster shells. We attempt to use this thermometry for a seasonally resolved reconstruction of the sea surface temperature, and the oxygen isotopic composition of the seawater when combined with the oxygen isotope thermometry. This study will shed new light on the reconstruction of temperature and climate short-scale oscillation and seasonality in the geological past.

英文关键词： clumped isotope;paleotemperature;bivalve shells;coastal and estuarine regions;high-resolution