RUI: Halogens in Granitic Systems

RUI：花岗岩系统中的卤素

• 批准号: 9902185
• 负责人: Michael Wolf
• 金额: $ 7.89万
• 依托单位: Augustana College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2003-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9902185&HistoricalAwards=false
• 关键词: RUI; Halogens; Granitic; Systems

9902185 Wolf Fluorine is a minor yet important gas emitted from many volcanoes. Its emission indicates that the molten rock, or magma, within the volcano contains but is slowly losing its fluorine. It is important for us to learn about fluorine in volcanic systems because the presence of this element in magmas affects a wide variety of fundamental parameters such as the viscosity, density and polymerization of the magma; the ability of other elements to bond within and diffuse through the magma; the conditions under which many minerals crystallize or melt; and the distribution of other elements between coexisting crystal, liquid and gas phases. Such knowledge is of great value in determining the ability of fluorine to act as a flux and mineralizer during the formation of granite-associated magmatic-hydrothermal ore deposits if we know more about the effects of fluorine on ore deposition, then we just may be able to use this information to help us find future ore deposits. One problem with this optimistic scenario, however, is that we need to know the fluorine content of the magma, but how can we do so if most of the fluorine was lost from the crystallizing magma before it solidified into rock? We can do so because certain minerals that grow in the magma incorporate fluorine into their structures and do not subsequently lose it. By measuring the fluorine content of these minerals, we may be able to determine the fluorine content of the magma from which these minerals grew. However, we can only do so if we know how much fluorine these minerals "sucked up" relative to the amount of fluorine in the coexisting magma (this parameter is called the distribution or partition coefficient), and we can only determine this parameter by doing experiments. Thus, in a series of high pressure and high temperature experiments simulating conditions beneath volcanoes, we will grow a variety of different fluorine-bearing minerals from a range of magma compositions to determine the fluorine contents in the coexisting phases, the corresponding distribution coefficients, and, when applied to real rocks, how much fluorine was in the magma initially and how much was lost.

9902185狼氟是许多火山喷出的一种微小但重要的气体。它的释放表明，火山内部的熔融岩石或岩浆含有氟，但正在缓慢地失去氟。对我们来说，了解火山系统中的氟是很重要的，因为这种元素在岩浆中的存在影响着各种各样的基本参数，如岩浆的粘度、密度和聚合；其他元素在岩浆内部结合并扩散的能力；结晶：许多矿物结晶或融化的条件；以及其它元素在共存的晶相、液相和气相之间的分布。这些知识对于确定氟在与花岗岩相关的岩浆热液矿床形成过程中充当助熔剂和矿化剂的能力具有重要价值，如果我们更多地了解氟对矿床的影响，那么我们就有可能利用这些信息帮助我们找到未来的矿床。然而，这种乐观设想的一个问题是，我们需要知道岩浆的氟含量，但如果大部分氟在结晶岩浆凝固成岩石之前就消失了，我们怎么能知道呢？我们之所以能够这样做，是因为在岩浆中生长的某些矿物将氟纳入其结构中，并且随后不会失去氟。通过测量这些矿物的氟含量，我们可能能够确定这些矿物生长的岩浆的氟含量。然而，我们只有知道这些矿物相对于共存岩浆中的氟含量“吸收”了多少氟才能做到这一点（这个参数称为分布或分配系数），我们只能通过做实验来确定这个参数。因此，在模拟火山下条件的一系列高压和高温实验中，我们将从一系列岩浆成分中生长出各种不同的含氟矿物，以确定共存相中的氟含量，相应的分布系数，并将其应用于实际岩石时，确定岩浆中最初含有多少氟以及损失了多少氟。