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

我们将对来自地壳剖面不同深度的辉长岩（地球内部结晶的火成岩）样品进行结构和地球化学研究 阿曼蛇绿岩（暴露在陆地上的海洋地壳构造切片）。 样品在地壳剖面中的“地层位置”是众所周知的，因此这些样品提供了一个极好的机会来确定火成岩结晶历史的垂直变化。 在过滤掉与成分有关的变化之后，我们将寻找上部和下部辉长岩之间冷却速率的系统相似性或差异， 使用纹理和组成特征，可以记录 岩浆结晶的初始阶段。 图像处理将用于获得晶体尺寸分布（CSD），以约束成核速率，生长速率和停留时间。这些参数的分析可用于估计结晶过程中的冷却速率。此外，EPR和SWIR辉长岩的纹理数据的分析将使我们能够评估阿曼的样品相比，从两个对比鲜明的洋中脊环境。这些研究将对大洋扩张脊岩浆系统的岩浆储存、热历史和结构演化提供制约。

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.