A high resolution account of Holocene climate variability along East Antarctica - An analysis of the IODP Wilkes land Expedition sediments

人们普遍认为海洋和极地海冰在全球气候变化中起着至关重要的作用。因此，海表温度和极地海冰重建对于确定地质过去的气候演化具有至关重要的意义。虽然过去200年的海冰直接记录被认为是相当准确的（利用过去30年的卫星成像），但只有通过使用“代理”措施（海冰的化学、物理或生物指标）才能获得更广泛的记录。当前项目的主要目的是测量高支异戊二烯类脂质的浓度，沿着IODP Wilkes陆地考察323期间检索的沉积物岩心。初步研究表明，这些化学物质在南极沉积物中是稳定的，虽然这些沉积物中特定异构体（二不饱和HBI异构体）的存在可以直接归因于以前的海冰覆盖，但发现这些沉积物中三不饱和HBI的存在反映了海冰的缺失。同样，过去的海洋表面条件（温度、分层）、海冰循环和硅质生产力变化可以通过硅藻组合测定和沉积物元素地球化学调查来研究。在这个合作项目中，我们将在整个全新世以前所未有的分季节分辨率对阿德利陆地地区检索的海洋岩心进行多代理分析。硅藻普查计数和元素分析将由项目伙伴完成。鉴于现有数据的多样性，加上高时间分辨率，该项目代表了一个独特的“案例研究”机会，可以建立不同代理之间的关系，并使将来的古气候重建研究得到更充分的理解。这个项目的数据也将被气候变化建模者直接使用。该项目与理事会计划的其他方面非常吻合，显然与“极南”分类和“全球变化”ENRI都有100%的相关性。该项目性价比极高，特别是考虑到项目合作伙伴的承诺。所有必要的化学和分析要求都在普利茅斯大学的石油和环境地球化学小组内部进行。该项目还将受益于当地和国际上现有的额外工作人员专业知识。

It is widely acknowledged that the oceans and polar sea-ice play critical roles in global climate change. As such, sea surface temperature and polar sea-ice reconstruction should be of paramount importance in establishing climatic evolution of the geological past. Although direct records of sea-ice are considered to be reasonably accurate over the last 200 years (with satellite imaging for the past 30 years), it is only through the use of 'proxy' measures (chemical, physical or biological indicators of sea-ice) that a more extended record is achievable. The main aim of the current project is to measure the concentrations of Highly Branched Isoprenoid lipids along a sediment core retrieved during the IODP Wilkes land Expedition 323. Preliminary studies have shown that these chemicals are stable in Antarctic sediments and, while the presence of a specific isomer (a di-unsaturated HBI isomer) in these sediments can be directly attributable to previous sea ice cover, the presence of a tri-unsaturated HBI in these sediments was found to reflect the absence of sea ice. Similarly, past surface oceanic conditions (temperature, stratification), sea ice cycles, and siliceous productivity variations can be investigated via diatom assemblage determinations and investigation of elemental geochemistry in sediments. In this collaborative project, we will carry out a multi-proxy analysis of a marine core retrieved in the Adelie land area at an unprecedented sub-seasonal resolution throughout the entire Holocene. The diatom census counts and elemental analyses will be completed by the project partners. Given the diversity of the data available, together with the high temporal resolution, this project represents a unique 'case study' opportunity to establish the relationships between different proxies and to enable future studies in palaeoclimate reconstruction to be more fully understood. The data from this project will also be used directly by modellers of climate change.This project fits well with other aspects of the Council's programme and clearly has a 100% relevance to both the 'Polar South' classification and the 'Global Change' ENRI. The project represents excellent value for money, especially considering the commitment of the project partners. All of the necessary chemical and analytical requirements are held in-house within the Petroleum and Environmental Geochemistry Group at the University of Plymouth. The project will also benefit from additional staff expertise available both locally and internationally.