Diamond, fluids and mantle metasomatism

对科学家来说，钻石不仅仅是另一种矿物。它的科学价值源于这样一个事实，即钻石提供了地球内部最深的地球化学探测器。钻石特殊的化学和物理性质使其能够存储和保存有关其起源地幔深处的信息。钻石也是独一无二的，因为它只出现在最古老的、有20-30亿年历史的大陆部分(即克拉通)。钻石及其流体和矿物包裹体记录了有关矿物学、成分和流体渗入古代岩石圈地幔的信息。世界上只有10个这样的稳定区块超过25亿年，关于每个区块的数据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钻石熔体是如何形成的，并利用这一信息限制了原始大陆及其深层根源的演化。交代作用是岩石在渗流流体驱动下的物理化学变化；地幔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产生携带钻石的熔体也是至关重要的。我的目标是限制交代流体在钻石形成过程和影响这些原始大陆的岩浆作用中的性质和作用。该项目将研究加拿大和世界各地钻石矿床中的几套钻石、地幔包体和含钻石岩石。传统的分析方法将包括光谱技术、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。这项研究还将为参与钻石勘探的加拿大公司提供重要的实用地质信息。

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.