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 Wolf 氟是许多火山喷出的一种次要但重要的气体。 它的排放表明火山内的熔岩或岩浆含有氟，但正在慢慢失去氟。 了解火山系统中的氟对我们来说非常重要，因为岩浆中氟的存在会影响岩浆的粘度、密度和聚合等多种基本参数；其他元素在岩浆内结合并扩散的能力；许多矿物结晶或熔化的条件；以及其他元素在共存晶体、液相和气相之间的分布。 这些知识对于确定氟在花岗岩伴生岩浆热液矿床形成过程中作为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石沉积的影响，那么我们也许能够使用这些信息来帮助我们寻找未来的矿藏。 然而，这种乐观情景的一个问题是，我们需要知道岩浆中的氟含量，但如果大部分氟在结晶岩浆凝固成岩石之前就从岩浆中流失了，我们该如何知道呢？ 我们可以这样做，因为在岩浆中生长的某些矿物质将氟纳入其结构中，并且随后不会失去它。 通过测量这些矿物的氟含量，我们也许能够确定这些矿物生长的岩浆中的氟含量。 然而，只有知道这些矿物“吸收”了多少氟相对于共存岩浆中的氟量（这个参数称为分布或分配系数），我们才能做到这一点，并且我们只能通过以下方式确定这个参数：实验。 因此，在一系列模拟火山下方条件的高压和高温实验中，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、相应的分配系数，以及，当应用于真实岩石时，岩浆中最初有多少氟以及损失了多少。