Peridotit xenoliths: a key to understanding exceptional depletion and re-enrichment of the lithospheric mantle beneath Greenland

地球不同的古大陆核（克拉通）在组成和结构上表现出显著的差异。然而，所有克拉通档案都加密了早期地球动力学和环境的信息，这些信息可以通过应用各种地球化学工具对暴露的地壳样本或零星岩浆活动期间夹带的岩石圈地幔样本进行解码。格陵兰岛的克拉通部分一直是科学研究的热点，因为它被发现包含一些地球上最古老的地壳，下面的岩石圈有巨大的钻石潜力。我们手上有一套新发现的金伯利岩夹带的橄榄岩捕虏体，其岩性范围从暗粒岩到黑兹伯尔岩和高度交代的微粒岩。利用详细的岩石学和原位分析方法获取主要和微量元素，以及矿物分离物和原位的多种放射性成因同位素系统（Sr, Sm-Nd, Lu-Hf, Re-Os），我们希望解决以下与早期陆地动力学直接相关的问题：(1)格陵兰克拉通下地幔岩石圈异常枯竭的原因是什么？垂直（地幔柱）和水平（俯冲）过程在其形成过程中起什么作用？(2)克拉通格林兰地壳与岩石圈地幔的形成是耦合的还是解耦的？(3)地幔岩石圈再富集的性质和时间及其与区域构造热事件的联系，特别是与小体积熔体（如含金刚石金伯利岩）的形成有何联系？

The Earths different ancient continental cores (cratons) show significant differences in their composition and structure. However, all cratons archive encrypted information on early Earth dynamics and environments that can be decoded by applying a variety of geochemical tools to exposed crustal samples or to lithospheric mantle samples entrained during sporadic magmatism. The cratonic part of Greenland has been a hotspot of scientific investigation since it was discovered that it contains some of the oldest crust on Earth and that the underlying lithosphere has significant diamond potential. We have in hand a newly recovered suite of fresh kimberlite-entrained peridotite xenoliths that range in lithology from dunites to harzburgites and highly metasomatised wehrlites. Using a detailed petrographic and in situ analytical approach for the acquisition of major and trace elements, as well as multiple radiogenic isotope systematics (Sr, Sm-Nd, Lu-Hf, Re-Os) of mineral separates and in situ, we would like to address the following questions that are directly relevant to early terrestrial dynamics: (1) What is the origin of the exceptional depletion of the mantle lithosphere beneath cratonic Greenland and what was the role of vertical (plumes) vs horizontal (subduction) processes during its nascence? (2) Was the formation of the crust and lithospheric mantle in cratonic Greenland coupled or decoupled? (3) What are the nature and timing of re-enrichment of mantle lithosphere and its link to regional tectonothermal events, in particular the formation of low-volume melts, such as diamondiferous kimberlites?