An Experimental Investigation of Melt Inclusion Formation, Phase Equilibria and Trace Element Partitioning in Anorthitic Feldspar in Natural Mafic Systems

9903137尼尔森在地幔过程模型的发展中使用的最重要的数据来源之一是我们在地球表面观察到的熔岩成分的多样性。 岩浆在运输过程中所经历的处理阻碍了获得此类信息。 未改性的岩浆可以从岩浆历史早期形成的晶体中的熔融包裹体中取样。 熔融包裹体资料表明，地幔中产生的岩浆成分范围很广。 然而，对于熔融包裹体是如何被捕获的，以及熔融包裹体的成分与岩浆的关系，我们仍然有很多不了解的地方。 本研究将着重探讨三个问题：（1）形成再加热过程对熔融包裹体成分的影响;（2）天然玄武岩中钙长石的相平衡。 长石是海底熔岩中最常见的矿物之一，但我们对它们形成的条件和成分的了解仍然很差;（3）为了解决前两个问题，并建立洋壳形成模型，我们需要关于元素如何在长石和岩浆之间分布的数据。 这些问题将在一系列实验中解决，这些实验旨在开发一种用于创建合成熔融包裹体的方法，并创建模仿熔融包裹体所代表的近原生岩浆的玄武质熔体。

9903137NielsenOne of the most important sources of data used in the development of models of mantle processes is the diversity of lava compositions we observe on the surface of the earth. Obtaining such information is hampered by the processing that magmas undergo during transport. Unmodified magmas may be sampled from melt inclusions in crystals that form early in the history of the magma. Melt inclusion data has demonstrated that there is a wide range of magma compositions generated in the mantle. However, there is still much that we do not understand about how melt inclusions were trapped, and how the composition of melt inclusions relate to the magmas. This investigation will focus on three issues: (1) The compositional effects of the process of formation re-heating on melt inclusions; (2) The phase equilibria of anorthitic feldspar in natural basalt. Feldspar is one of the most common minerals in ocean floor lavas, yet our understanding of the conditions and compositions under which they form is still very poor; and (3) To address the first two issues, and to model the formation of the oceanic crust, we need data on how elements distribute themselves between feldspar and magma. These issues will be addressed in a series of experiments designed to develop a means for creating synthetic melt inclusions, and to create basaltic melts that mimic the near-primary magmas represented by the melt inclusions.