Diamond, fluids and mantle metasomatism

对科学家来说，钻石不仅仅是一种矿物。它的科学价值源于这样一个事实，即钻石提供了对地球内部最深的地球化学探测。钻石独特的化学和物理特性使其能够储存和保存有关其起源地函深处的信息。钻石的独特之处在于，它只存在于最古老的大陆板块中，有20 - 30亿年的历史（即克拉通）。钻石及其流体和矿物包裹体记录了通过古代岩石圈地幔渗透的矿物学、成分和流体的信息。世界上只有10个这样的稳定块超过25亿年，每个块的数据都为了解古代地质过程和大陆的形成提供了宝贵的见解。这项拟议的研究调查了钻石和含金刚石的熔体是如何形成的，并利用这些信息来限制原大陆的演化及其深层根源。交代作用是由渗流流体驱动的岩石物化转化作用；地幔的交代作用可能是金刚石形成的一个因素。地幔流体和气体对于形成包裹钻石的熔体也至关重要。我的目标是约束交代流体在钻石形成过程和影响这些原大陆的岩浆活动中的性质和作用。该项目将研究来自加拿大和世界各地钻石矿床的几组钻石、地幔捕虏体和含金刚石岩石。传统的分析方法包括光谱技术、电子显微分析、显微镜和质谱分析。此外，我们将开发一种创新技术，使用x射线衍射来识别钻石宿主中包含的微米级矿物。这项研究还将为从事钻石勘探的加拿大公司提供重要的实用地质资料。

For scientists, diamond is not just another mineral. Its scientific value stems from the fact that diamond offers the deepest geochemical probe of the earth's interior. The exceptional chemical and physical properties of diamond allow it to store and preserve information about the deep mantle from where it originates. Diamond is also unique in that it occurs only in the most ancient, 2-3 billion year old segments of continents (i.e., cratons). Diamonds and their fluid and mineral inclusions record information about the mineralogy, composition and fluids percolating through the ancient lithospheric mantle. There are only 10 blocks of such stabilization older than 2.5 billion years in the world, and data on each of them provide invaluable insights into ancient geological processes and the formation of continents. The proposed research investigates how diamonds and diamondiferous melts are formed, and uses this information for constraints on the evolution of the proto-continents and their deep roots. Metasomatism is the physicochemical transformation of rocks driven by percolating fluid; metasomatism of the mantle may be a factor in diamond formation. Mantle fluids and gases are also crucial for generation of melts that entrain diamonds. I aim to constrain the nature and role of the metasomatic fluids in, both, diamond-forming processes and in magmatism affecting these proto-continents. The program will study several suites of diamonds, mantle xenoliths and diamondiferous rocks from Canadian and worldwide diamond deposits. Traditional analytical methods will include spectroscopic techniques, electron microanalysis, microscopy and mass-spectrometry. In addition, we will develop an innovative technique that will use X-ray diffraction for identification of micron-size minerals included in diamond hosts. This research will also provide important practical geological information to Canadian companies involved in diamond exploration.