Applications of geochemistry to igneous petrology

地球化学在火成岩岩石学中的应用

• 批准号: 116416-2007
• 负责人: Greenough, John
• 金额: $ 1.06万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=364030
• 关键词: Applications; geochemistry; igneous; petrology

Questions of interest and importance to us all are how did the oceans, continents, atmosphere and interior of the Earth form, and how do these Earth systems operate and interact today. Answers affect our understanding of present-day climate, human impacts on the atmosphere and ocean, and where to look for resources that sustain society. A problem is that the largest part of the Earth, the mantle (interior of Earth), is inaccessible and our understanding of it is poor. My research uses basalt lava flows to study the interior of the Earth. Basalts are the most common rocks on Earth and they form due to melting of the mantle. Studies of basalts from the ocean basins tell us that there are different types of mantle. For example, one type apparently had elements such as potassium and silicon extracted from it to form the continents billions of years ago. Other types may contain "recycled" rocks that were once at the Earth's surface. Mantle rocks beneath the continents appear to have unusual compositions that make them the source of most diamonds. An important question is how the types of mantle formed because they will contain a record of how the planet's oceans, continents and atmosphere evolved. By comparing the concentrations of elements in different "basalts" from the ocean basins and continents, it will be possible to answer these questions. However, the comparisons are not easy. For example, when molten basalt crystallizes to form minerals, different elements enter different minerals. Some minerals form early and some form late. The result is that the composition of a basalt changes as elements get used up. This process is called "differentiation". Although this complicates studying the interior of the Earth, these processes can lead to ore deposits because some minerals that form are rich in nickel, chromium, platinum and other valuable elements. In summary, the research is of substantial human interest because basalts are important to understanding the evolution of the Earth. However, the work also has economic implications. It may help explain why some ore deposits (e.g. diamonds and platinum) occur where they do, or point to chemical tests that assist in discovering new deposits.

我们所有人感兴趣和重要的问题是海洋、大陆、大气和地球内部是如何形成的，以及这些地球系统今天是如何运作和相互作用的。这些问题的答案会影响我们对当今气候、人类对大气和海洋的影响以及在哪里寻找维持社会的资源的理解。问题是，地球的最大部分，地幔（地球内部），是难以接近的，我们对它的了解很少。我的研究使用玄武岩熔岩流来研究地球内部。玄武岩是地球上最常见的岩石，它们是由于地幔融化而形成的。对海洋盆地玄武岩的研究告诉我们，地幔有不同的类型。例如，其中一种显然含有钾和硅等元素，在数十亿年前形成了大陆。其他类型的岩石可能含有曾经在地球表面的“再循环”岩石。大陆下面的地幔岩石似乎具有不同寻常的成分，使它们成为大多数钻石的来源。一个重要的问题是地幔的类型是如何形成的，因为它们将包含地球海洋、大陆和大气如何演变的记录。通过比较来自海洋盆地和大陆的不同“玄武岩”中元素的浓度，将有可能回答这些问题。然而，进行比较并不容易。例如，当熔融的玄武岩结晶形成矿物时，不同的元素进入不同的矿物。有些矿物形成早，有些形成晚。结果是玄武岩的成分随着元素的消耗而改变。这个过程被称为“分化”。虽然这使研究地球内部变得复杂，但这些过程可以导致矿床，因为形成的一些矿物富含镍、铬、铂和其他有价值的元素。总而言之，这项研究具有重大的人类利益，因为玄武岩对了解地球的演化非常重要。然而，这项工作也有经济意义。它可能有助于解释为什么有些矿床（如钻石和铂）会在它们所在的地方出现，或者指出有助于发现新矿床的化学试验。