Constraints on the Accretion of the Lower Oceanic Crust: A Quantitative Textural and Geochemical Study of Gabbros from the Oman Ophiolite and the Mid-Ocean Ridges

我们将对来自阿曼蛇绿岩（暴露在陆地上的海洋地壳构造片）地壳剖面不同深度的辉长岩（地球内部结晶的火成岩）样本进行结构和地球化学研究。地壳剖面中样品的“地层位置”是众所周知的，因此这些样品为确定火成岩结晶历史的垂直变化提供了极好的机会。在过滤掉与成分相关的变化之后，我们将利用可能记录火成岩结晶初始阶段的结构和成分特征，寻找上下辉长岩冷却速率的系统相似性或差异性。图像处理将用于获得晶体尺寸分布（CSD），以限制成核速率，生长速率和停留时间。对这些参数的分析可以用来估计结晶过程中的冷却速率。此外，对EPR和SWIR辉长岩的纹理数据进行分析，将使我们能够评估阿曼样品与来自两个不同洋中脊环境的样品的对比。这些研究将为海洋扩张脊岩浆系统的岩浆储存、热史和构造演化提供约束条件。

We will conduct a textural and geochemical study of samples of gabbro (igneous rocks crystallized within the Earth) from different depths of the crustal section of the Oman ophiolite (a tectonic slice of oceanic crust exposed on land). The "stratigraphic position" of samples in the crustal section is well known, and therefore these samples provide an excellent opportunity to determine vertical variation in igneous crystallization histories. After filtering out variation that is related to composition, we will look for systematic similarities or differences in cooling rates between upper and lower gabbros, using textural and compositional characteristics that may record the initial stages of igneous crystallization. Image processing will be used to obtain crystal size distributions (CSD) to constrain nucleation rates, growth rates and residence times. Analysis of these parameters can be used to estimate cooling rates during crystallization. Additionally, analysis of textural data on EPR and SWIR gabbros will allow us to assess how Oman samples compare with those from two contrasting mid-ocean ridge environments. Such studies will provide constraints on the magma storage, thermal history and structural evolution of magmatic systems at oceanic spreading ridges.