El´gygytgyn impact structure, Siberia: Investigation of a mid-size impact structure in volcanic target.

位于俄罗斯东北部楚科特卡的年轻陨石坑(3.6 Ma)，直径18公里，是地球上保存最完好的撞击结构之一。这个复杂的陨石坑结构是在一个硅质的火山目标上形成的，这使得它成为地球上罕见的相当于其他行星表面(例如火星)火山岩中丰富的撞击结构的陨石坑。撞击后形成了一个火山口湖，在其中发生了不受干扰的持续的湖泊沉积，建立了一个连续的、长期的古环境信息储存库。陨石坑从来没有被冰川或冰盾覆盖，这使得一个独特的北极气候档案得以发展。2009年春季，“国际大陆钻探项目”的钻探活动发现了一个完整的(517米)湖泊沉积物和撞击岩序列(317米的湖泊、撞击后的沉积物、几米宽的向下的撞击角砾岩的过渡带--超过170米的单一岩屑角砾岩--25米岩浆岩)。钻探的目标是：(1)收集北极陆地气候历史的史无前例的记录，(2)便于在罕见的地质环境中研究这种独特的撞击结构的火山口填充和火山口底部地质。在这里，我们建议岩相学(包括。冲击变形)和化学(包括射弹识别)项目旨在阐明该钻芯中撞击序列的形成，并结合基于这些结果的数值模拟(在第二阶段)，更好地了解在产生这种复杂的撞击结构时所涉及的撞击过程。

The young (3.6 Ma), 18 km diameter El´gygytgyn crater in Chukotka, NE Russia, is one of the best-preserved impact structures on Earth. The complex crater structure was formed in a silicious volcanic target, which makes it a rare terrestrial equivalent to the abundant impact structures in volcanics on other planetary surfaces (e.g., on Mars). After the impact a crater lake formed – within which undisturbed and continued lacrustrine sedimentation took place to establish a continuous, long-term reservoir of paleoenvironmental information. The crater was never covered by glaciers or ice shields, which allowed the development of a unique arctic climate archive. In spring 2009 a drilling campaign by the “International Continental Drilling Project (ICDP)” recovered a complete (517 m) sequence of lake sediments and impactites (317 m of lacustrine, post-impact sediments, a several m wide transition zone to the underlying impact breccias - 25 m suevite above 170 m monomict lithic breccia). The goals for drilling were: (1) to collect an unprecedented record of climate history in the terrestrial arctic, and (2) to facilitate study of the crater fill and the crater floor geology of this unique impact structure in a rare geological setting. Here we propose a petrographic (incl. shock deformation) and chemical (incl. projectile identification) project aimed at elucidating the formation of the impactite sequence in this drill core, and – in conjunction with numerical modeling based on these results (during phase 2) – at a better understanding of the impact processes involved in generation of this complex impact structure.