Tracing paleo-permafrost with meteoric 10Be and in-situ 26Al/10Be - A proof of concept

确定覆盖西伯利亚东北部的厚的含碳永久冻土土壤的过去热状况对于理解上新世-更新世碳封存，长期气候冷却和限制未来释放储存碳的潜力至关重要。该项目将开发和应用一种新的流星Berlene-10（10 Be）技术，配合现场铝-26/Berlene-10（26 Al/10 Be）计时器，以确定西伯利亚北极El'gygytgyn撞击坑内从上新世中期撞击到今天的冻土热历史。结果将提供不仅在2008年没有其他年龄控制存在的141米钻芯下部的年表，但也将允许更好地了解的速率和风格的冻土建设使用最近开发的等时线法解释沉积物中的26铝/10铍比。在这里，我们试图使用一种已知的地球化学示踪剂，以一种新的方式，它提供了一个记录的热制度的土壤从降水衍生（流星）10 Be。当冻结时，土壤不会积累流星10 Be;当解冻时，10 Be通过活动层迁移。我们的研究将调查使用这种同位素示踪剂，以确定相对持续时间土壤经历了解冻的条件，因为沉积。这些信息与El'gygytgyn湖岩心的气候代用指标相联系，将产生过去温度与永久冻土融化深度之间的关键联系，并在预期全球变暖的背景下，对过去温暖和寒冷事件对永久冻土生成和维持的影响提供现实的限制。该方法可以推广到其他北极地区，以确定其他碳库的历史和命运。

Determining the past thermal regime of thick carbon-bearing permafrost soil blanketing northeastern Siberia is critical for understanding Plio-Pleistocene carbon sequestration, longterm climate cooling and constraining the potential for release of this pool of stored carbon in the future. This project will develop and apply a novel meteoric Beryllium-10 (10Be) technique in concert with the in-situ Aluminum-26/Beryllium-10 (26Al/10Be) chronometer in order to determine the thermal history of permafrost within the El’gygytgyn impact crater in the Siberian Arctic from time of the mid-Pliocene impact to today. The results will provide not only a chronology within the lower parts of the 141 m core drilled in 2008 where no other age control exists, but will also allow a better understanding of the rate and style of frozen ground build-up by using a recently developed isochron method for interpreting 26Al/10Be ratios in sediments. Here, we attempt to use a known geochemical tracer in a new way, which provides a record of the thermal regime of the soil from precipitation-derived (meteoric) 10Be. When frozen, soil does not build up meteoric 10Be; when thawed, 10Be migrates through the active layer. Our research will investigate the use of this isotope tracer for determining the relative duration soils have experienced thawed conditions since deposition. This information, when linked with climate proxies from the Lake El’gygytgyn cores, will yield key connections between past temperatures and depth of permafrost thaw and to provide realistic constraints on the impact of past warm and cold episodes on permafrost generation and maintenance in the context of anticipated global warming. The method can be extended to other Arctic terrains to determine the history and fate of other carbon reservoirs.