报告时间：11月26日（星期一）下午1:30-3:00
报告地点：天津大学地科院（第16教学楼）221报告厅
主讲嘉宾：周晓理博士
报告摘要：Cenozoic climate has transitioned from a warmhouse to an icehouse, manifest as decreasing seawater temperature and atmospheric pCO2. What caused the changes in temperature and pCO2, however, has not been fully resolved. Since ocean chemistry is tightly coupled with global carbon cycle on multi-million-year timescale, studies on ocean chemistry can provide potentials to understand long-term changes in carbonate system including pCO2. Major ion concentrations such as Mg and Ca concentrations in seawater ([Mg]sw and [Ca]sw) presumably have changed over the Cenozoic, but existing proxies yielded inconsistent [Mg]sw and [Ca]sw records. To resolve this problem, here I propose to use Na/Ca in foraminifera as a proxy for [Ca]sw. This proxy is testified by culture experiments and core-top samples. The downcore Na/Ca records of three species of foraminifera are generated from multiple locations in the Atlantic and Pacific Ocean. A generally increasing trend in the Na/Ca records suggests a monotonic decrease in [Ca]sw and increase in (Mg/Ca)sw since Eocene. Such a long-term change in [Ca]sw and (Mg/Ca)sw may be a result of coupled changes in continental weathering and hydrothermal flux. High [Ca]sw suggests low carbonate ion concentration ([CO32-]) in the early Cenozoic, which may have the potential to sustain high pCO2 at that time.
个人简介：周晓理博士于 2011 年本科毕业于中国科学技术大学。之后在 2016 年于美国 Syracuse University 获得博士学位，师从陆尊礼教授，用碳酸钙中的碘钙比研究古海洋中氧气含量的变化，其研究结果以第一作者发表在 Paleoceanography and Paleoclimate，Chemical Geology 等期刊上。目前为 Rutgers University 博士后，用有孔虫壳体中的钠钙比研究新生代海洋主量元素的浓度变化，以及它与同时期全球气候变化和大陆风化速率之间的关系。曾作为无机地球化学家参与国际大洋钻探计划西南太平洋航次（IODP 371），并将于2019 年参与东南太平洋航次（IODP 379T）。
