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

该奖项将由大气科学部的北极自然科学项目和古气候项目资助。这是马萨诸塞大学首席研究员与马加丹、圣彼得堡和符拉迪沃斯托克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——西伯利亚高地和阿留申低地之间。阿留申低压的强度与热带地区的系统变化密切相关，这一点在对强劲的太平洋-北美模式（PNA）变化的分析中得到了反映。产生PNA模式的系统被认为与全球环流在长时间尺度上具有强大的联系，从而可以评估在可变边界条件下的半球间远距联系。1998年，从El'gygytgyn湖提取了30万年的沉积物核气候记录，这是迄今为止发现的最古老的北极陆地记录。这一记录揭示了富氧和无氧湖底条件之间的逆转，可以想象，这是由夏季永久冰层的存在或缺失所驱动的，并与区域大气条件的变化有关。因此，了解湖冰的动态非常重要，特别是确定其形成和融化的环境条件及其对湖泊环流的影响。该研究项目将提供对沉积物沉积后变化的理解和对一些代用物的控制，这些代用物产生了具有半球意义的气候信号。未来的野外项目将包括获取新的重力岩心，用于沉积学和矿物学研究，以及有机物的生物地球化学研究，以及湖水和沉积物孔隙水的同位素地球化学研究。然后将这些现代与近代的过程联系与古记录进行比较，以更好地量化沉积时期湖泊生物地球化学的可靠核心代用物。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（根据与格陵兰冰芯记录的一些匹配推断）持续时间足够长，以至于它们被记录在西伯利亚的一个湖泊中。人们不会期望整个北极都同步响应，因此，比较北极不同地区的记录以更充分地了解地球系统一部分的变化如何影响系统的其他部分是很重要的。

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.