Proxy development and paleoclimate of El'gygytgyn Crater Lake, NE Siberia

该奖项将由北极自然科学计划和大气科学部的古气候计划资助。 这是马萨诸塞州大学的首席研究员与马加丹、彼得堡和海参崴的俄罗斯同事以及阿尔弗雷德·韦格纳研究所和莱比锡大学的德国同事合作提出的一项建议。 El'gygytgyn湖位于一个18公里宽的陨石撞击坑内，该陨石撞击坑形成于360万年前，位于西伯利亚东北部（楚科奇）的偏远地区，位于两个强大的大气特征之间，西伯利亚高压和阿留申低压。 阿留申低压的强度与热带的系统性变化密切相关，这一点可以通过对太平洋-北美模式（PNA）的变化分析来反映。 据信，产生PNA模式的系统学在长时间尺度上与全球环流有着强有力的联系，从而可以在可变边界条件下评估半球间的遥相关，1998年，从El'gygytgyn湖检索到了30万年的沉积物核心气候记录，这是迄今为止发现的最古老的北极陆地记录。 这一记录揭示了好氧和缺氧湖底条件之间的逆转，可以想象，这是由夏季永久冰盖的存在或不存在所驱动的，并与不断变化的区域大气条件有关。 因此，重要的是要了解湖冰的动态，特别是确定它形成和融化的环境条件及其对湖泊环流的影响。 这一研究项目将使人们了解沉积物的沉积后变化，并对产生具有半球意义的气候信号的一些代用指标进行控制。 未来的现场项目将包括获取新的重力岩心，用于沉积学和矿物学沿着研究，以及有机物的地球化学、湖泊沃茨和沉积物孔隙沃茨的同位素地球化学研究。 这些现代到最近的过程联系，然后将比较古记录，以更好地量化可靠的核心代理湖泊沉积时的地球化学。该项目的主要目标之一是确认或修改湖泊记录的代用地球化学，以考虑为什么大气环流的变化（从与格陵兰冰芯记录的一些匹配中推断）持续足够长的时间，以至于在西伯利亚的一个湖泊中记录下来。 人们并不期望整个北极同步响应，因此将北极不同地区的记录进行比较，以更全面地了解地球系统一部分的变化如何影响系统的其他部分，这一点很重要。

This award will be funded by the Arctic Natural Sciences Program and the Paleoclimate Program in the Division of Atmospheric Sciences. This is a collaborative proposal by the Principal Investigator at the University of Massachusetts, with Russian colleagues in Magadan, St. Petersburg, and Vladivostok, and German colleagues at the Alfred Wegener Institute and University of Leipzeg. Lake El'gygytgyn is located within an 18 km wide meteorite impact crater that formed 3.6 million years ago in a remote part of northeastern Siberia (Chukotka) and in a region of situated between two robust atmospheric features, the Siberian High and Aleutian Low. The strength of the Aleutian Low is intimately linked to systematic changes in the tropics as reflected by analyses of variations in the robust Pacific-North American pattern (PNA). The systematics that produce the PNA pattern are believed to have robust linkages over long time scales with global circulation, allowing an evaluation of inter-hemispheric teleconnections under variable boundary conditions.In 1998, a 300,000-year sediment-core climate-record was retrieved from Lake El'gygytgyn, the oldest terrestrial Arctic record yet recovered. This record reveals reversals between oxic and anoxic lake-bottom conditions, conceivably driven by the presence or absence of permanent ice cover through summer and linked to changing regional atmospheric conditions. Therefore, it is important to understand the dynamics of the lake ice, specifically determining the environmental conditions in which it forms and melts and its effects on lake circulation. This research project will provide an understanding the post-depositional modification of the sediments and controls on a number of proxies yielding a climatic signal of hemispheric significance. Future field programs will incorporate the acquisition of new gravity cores for study of the sedimentology and mineralogy along with the biogeochemistry of the organic matter, and the isotopic geochemistry of the lake waters and sediment porewaters. These modern to recent process linkages will then be compared to the paleorecord to better quantify reliable core proxies of lake biogeochemistry at time of deposition. One of the primary goals of this project is to confirm or revise the proxy geochemistry from the lake record to consider why shifts in atmospheric circulation (as inferred from some matches with the Greenland Ice core record) persist long enough that they are recorded in a lake in Siberia. One does not expect the entire Arctic to respond in synchroneity, so it is important that records from different parts of the Arctic be compared to more fully understand how changes in one part of the Earth system impact other parts of the system.