OCE-RIG: Crustal and Mantle Processes at Gorda Ridge Based on Olivine-Hosted Melt Inclusion Compositions

该项目的目标是确定洋中脊洋壳内岩浆结晶的深度和分布。 形成海洋地壳的岩浆结晶过程中释放的潜热是热量从地球内部转移到海洋和大气层的主要机制，它驱动着维持海底化学合成生命的热液循环。 因此，确定结晶发生在岩浆系统内，以及岩浆如何分布到洋壳是至关重要的，我们了解全球地球化学循环和大洋中脊系统作为一个整体。该项目将为博伊西州立大学（BSU）的研究生和本科生提供资金和研究经验，其结果将纳入BSU的一门新的海洋地球科学课程。该项目的主要目标是确定扩张速率、脊轴形态和岩石圈厚度的变化如何影响沿着戈尔达脊的结晶深度和岩浆成分。研究人员将使用主要的，微量和挥发性成分的橄榄石托管熔融包裹体，以解决三个问题，熔融和结晶：（1）结晶深度如何变化沿着戈尔达海脊，这表明岩石圈厚度？(2)是否有岩浆成分和熔融系统学的变化与海脊形态相关？(3)北戈尔达之下的熔融系统学和结晶深度与胡安·德富卡海岭的裂缝段相比如何？为了解决这些问题，研究人员将使用来自挥发性成分的蒸汽饱和压力来确定每个熔体包裹体的结晶压力/深度。接下来，主要和微量元素浓度将用于确定岩浆成分如何沿沿着脊轴变化。 这些结果将被纳入数值计算，以确定地幔源成分和总的熔融程度如何沿沿着变化。 最后，结晶深度和熔融模型将与以前对各种海脊熔融包裹体的研究进行比较，以确定扩张速率、岩浆供应和岩石圈厚度的变化如何影响大洋中脊下的熔融和结晶。

The goal of this project is to determine the depths and distribution of crystallization of magmas within the oceanic crust at mid-ocean ridges. The release of latent heat during crystallization of magmas that forms the oceanic crust is a primary mechanism by which heat is transferred from the Earth's interior to the oceans and atmosphere, and it drives the hydrothermal circulation that sustains chemosynthetic life on the seafloor. Thus, determining where crystallization occurs within the magmatic system and how magmas are distributed to the oceanic crust is critical for our understanding of global geochemical cycles and mid-ocean ridge systems as a whole. This project will provide funding and research experience for a graduate and undergraduate student at Boise State University (BSU) and results will be incorporated into a new marine geosciences course at BSU.The primary goal of this project is to determine how variations in spreading rate, ridge axis morphology, and lithospheric thicknesses influence crystallization depths and magma compositions along Gorda Ridge. The investigator will use major, trace and volatile compositions of olivine-hosted melt inclusions to address three questions regarding melting and crystallization: (1) How do crystallization depths vary along Gorda Ridge and what does this indicate about lithospheric thickness? (2) Are there variations in magma compositions and melting systematics that correlate with ridge morphology? (3) How do melting systematics and crystallization depths beneath North Gorda compare to the Cleft segment on the Juan de Fuca Ridge? To address these questions, the investigator will determine the pressures/depths of crystallization of each melt inclusion using vapor-saturation pressures derived from volatile contents. Next, major and trace element concentrations will be used to determine how magma compositions vary along the ridge axis. These results will be incorporated into numerical calculations to determine how mantle source compositions and total extents of melting vary along axis. Finally, crystallization depths and melting models will be compared to previous studies of melt inclusions from a variety of ridges to determine how variations in spreading rate, magma supply and lithospheric thickness influence melting and crystallization beneath mid-ocean ridges.