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.
