Characterization of the Timing and Nature of Metasomatism in the Siberian Lithospheric Mantle

这个项目解决了关于地球进化的一个基本问题？大陆是如何随时间形成和成长的。克拉通是我们大陆最古老和最稳定的部分，是我们大陆形成和增长的核心。稳定而古老的克拉通被认为是在地球历史的早期通过一个过程形成的，这个过程涉及到岩浆的提取，最终产生一个成分上有浮力的地壳和下面的岩石圈地幔。古老的克拉通，如南非的卡帕瓦尔克拉通、加拿大的奴隶克拉通和俄罗斯的西伯利亚克拉通，都以产有含钻石的金伯利岩以及发现其他有价值的矿产资源而闻名。由于这些克拉通很深，我们无法通过钻探对其进行充分采样，他们的研究需要获得地球深处的样品(捕虏体、钻石、钻石包裹体)，这些样品在爆炸性火山喷发(金伯利岩、钾镁岩)中被带到地表。西伯利亚克拉通含有1000块金伯利岩，分布于整个克拉通，其中包含的证据将被用来重建这一上亚大陆核心的形成、发展和演化。拟议的研究将以田纳西大学(UT)和俄罗斯科学院(IGM)位于新西伯利亚的西伯利亚分院的V.S.索博列夫地质矿产研究所之间的正式科学条约为基础，在阿卡德的指导下进行。研究计划包括调查西伯利亚克拉通不同年龄组金伯利岩管中的橄榄岩包体的地球化学和矿物学变化，以解决以下问题：a)随着时间的推移，其次大陆地幔的成分和热结构是什么；b)地幔中发生的交代作用的类型、过程、来源及其时间；以及c)导致橄榄岩包体中形成带状石榴石(次钙质到榴辉岩)的交代事件的条件和时间尺度是什么？预计这些不同的数据集将被整合，以提供对西伯利亚克拉通的更全面的看法。

This project addresses one of the fundamental issues about the evolution of the Earth ? how continental form and grow through time. Cratons are the oldest and most stable parts of our continents and act as the nuclei for the formation and growth of our continents. Stable and old cratons are believed to be formed early in the history of our planet through a process that involves the extraction of magma that eventually yields a compositionally buoyant crust and underlying lithospheric mantle. Old cratons such as the Kaapval Craton in South Africa, Slave Craton in Canada, and the Siberian Craton in Russia are well-known for their occurrences of diamond-bearing kimberlites as well as the sites for finding other valuable mineral resources. Because these cratons are deep and we cannot sample them adequately through drilling, their study require access to samples of the deep Earth (xenoliths, diamonds, diamond inclusions) that are carried to the surface in explosive volcanic eruptions (kimberlites, lamproites). The Siberian Craton contains 1000 kimberlites that are distributed across the craton and contain evidence that will be used to reconstruct the formation, development, and evolution of this core of the upper Asian continent. The proposed research will be conducted as a consortium effort, built on a formal scientific treaty between the University of Tennessee (UT) and the V.S. Sobolev Institute of Geology and Mineralogy in the Siberian Branch of the Russian Academy of Sciences (IGM) in Novosibirsk, under the direction of Akad. Nickolai P. Pokhilenko.The research plan includes the investigation of geochemical and mineralogical variations of peridotite xenoliths from kimberlite pipes of different age groups across the Siberian Craton in order to address the following questions: a) What were the composition and thermal structure of its sub-continental mantle over time; b) What were the styles, processes, and sources of metasomatism that occurred in the mantle and their timing; and c) What were the conditions and time scales of the metasomatic events that led to the formation of zoned garnets (sub-calcic to eclogitic) in peridotite xenoliths? It is expected that these various data sets will be integrated to provide a more comprehensive view of the Siberian craton.