Stable Isotope Investigation of a Fossil Hydrothermal System in Oceanic Crust Formed at a Superfast Spreading Rate (ODP/IODP Hole 1256D)

智力价值：这项研究调查了美国国家科学基金会海洋钻探计划(IODP孔1256D)收集的钻芯中的热液蚀变岩石，该钻芯穿透了从枕状熔岩到下面的辉长岩的整整1公里厚的洋壳。从热液特征和与海水反应的角度，分析和研究了该段脉状和块状岩石次生矿物中的微量元素以及O、H、S和C的稳定同位素。目标将是检查硬石膏是否记录了与海水排放的反应，确定流体在什么温度下穿透和改变席状岩脉边缘和辉长岩，在什么温度下形成硅酸盐蚀变矿物，以及什么类型的流体形成它们。矿物对的同位素分析将用作地温计。通过对典型块状岩石的S含量和同位素组成的分析，可以确定硫的收支。更广泛的影响：这项工作将为一名女性博士后研究员提供支持，并支持密歇根大学稳定同位素实验室的机构基础设施。这项工作的成果将纳入海洋地质学的本科课程。

Intellectual Merit: This research investigates hydrothermally altered rocks in a drill core collected by NSF's Ocean Drilling Program (IODP Hole 1256D), which penetrates a complete 1 km thick section of ocean crust from pillow lavas to underlying gabbroic rocks. Trace elements as well as stable isotopes of O, H, S, and C in secondary minerals from veins and bulk rocks from the section will be analyzed and examined in terms of hydrothermal signatures and reactions with seawater. Objectives will be to examine whether anhydrite records reactions with seawater discharge, determine at what temperatures fluids penetrate and alter sheeted dike margins and gabbros, at what temperatures silicate alternation minerals form, and what types of fluids form them. Isotope analyses of mineral pairs will be used as geothermometers. Analysis of the S contents and isotope compositions of representative bulk rocks will enable determination of the sulfur budget. Broader Impacts: This work will provide support for a female post-doctoral researcher and support the institutional infrastructure for the stable isotope laboratory at the University of Michigan. Results of the work will be incorporated into undergraduate courses in Marine Geology.