RUI Collaborative Research: Experimental Investigation of Fluid-Rock Interaction in Back-Arc Environments

最近来自刘弧后盆地的巡航结果证明，热液流体成分与全球大洋中脊(MOR)系统沿线的喷口有很大不同。此外，在这种弧后环境中，还观察到了局部和区域流体成分的系统变化。弧后热液系统可能受到许多独特的地质变量的控制，包括地下是否存在长英质火山岩，以及岩浆成因的流体对流体成分贡献的可能性要大得多。正是这些复杂的地质因素，可能解释了MOR和弧后热液之间的巨大差异，以及在单个弧后系统中观察到的流体成分的区域差异。由于这些复杂性，目前对弧后环境中热液流体的起源和演化模型的约束很差，因为尚未系统地研究与海水热液流体和长英质火山岩的反应有关的化学过程。这项研究是对海水热液流体与安山岩、英安岩和流纹岩成分的岩石相互作用过程中发生的特殊化学过程的实验室研究。这些实验将提供必要的基本信息，以确定调节弧后热液系统中流体化学的关键过程。刘盆地已被指定为山脊综合研究地点，拟议的研究将进一步加深我们对这一复杂的热液环境的了解。这项NSF-RUI调查是伍兹霍尔海洋研究所(WHOI)和布里奇沃特州立学院(BSC)基于实验室的合作，将研究和教育相结合的新尝试。该项目将使Saccocia博士能够进行与Ridge倡议相关的实验室研究，从而参与如果没有WHOI合作者就不可能进行的尖端研究。其次，研究议程将构成BSC地球科学本科生研究课程的基础。本课程将招收5-10名学生，在为期三年的授权期内每年春季学期提供。每个学生将1)阅读同行评议文献中的相关文章以了解拟议研究的背景，2)通过团队合作积极参与与实验相关的分析工作(在世界卫生组织)，3)在数据产生时解释结果，4)撰写报告描述他们分析团队的重要科学结果，以及5)为制作模仿期刊文章格式的单一手稿做出贡献。因此，瑞氏基金将为BSC最多30名地质学学生提供独特的本科生研究体验，使他们更有竞争力地申请高质量的研究生课程，并增加他们从事地球科学职业的可能性。除了研究课程，该项目还为BSC的最多6名本科生提供了一个机会，在夏季的几个月里在世界卫生组织的热液实验室进行更深入的研究。

Recent cruise results from the Lau back-arc basin documents hydrothermal fluid compositions that differ greatly from the well-studied vents along the global Mid-Ocean Ridge (MOR) system. Moreover, systematic local and regional variations in fluid composition within this back-arc environment have also been observed. Back-arc hydrothermal systems are likely controlled by a number of unique geologic variables, including the presence of felsic volcanic rocks in the subsurface and the much greater likelihood that fluids of magmatic origin contribute to fluid composition. It is these complex geologic factors that likely account for both the large differences between MOR and back-arc hydrothermal fluids and the regional variations in fluid composition observed within a single back-arc system. As a consequence of these complexities, models for the origin and evolution of hydrothermal fluids in back-arc environments are, at present, poorly constrained because the chemical processes associated with the reaction of seawater-derived hydrothermal fluids and volcanic rocks of felsic composition have not been systematically studied. This study is a laboratory investigation of the specific chemical processes that occur during the interaction of seawater-derived hydrothermal fluids with rocks of andesitic, dacitic, and rhyolitic compositions. These experiments will provide fundamental information necessary to identify key processes that regulate fluid chemistry in back-arc hydrothermal systems. The Lau Basin has been designated as a RIDGE Integrated Study Site and the proposed research will further our understanding of this complex hydrothermal environment.This NSF-RUI investigation is a novel integration of research and education through a laboratory-based collaboration between the Woods Hole Oceanographic Institution (WHOI) and Bridgewater State College (BSC). The project will allow Dr. Saccocia to conduct laboratory-based research relevant to the RIDGE initiative and thereby participate in cutting-edge research that would not otherwise be possible without a WHOI collaborator. Second, the research agenda will form the basis of an undergraduate research course in Earth Science at BSC. This course will enroll anywhere from 5-10 students and will be offered each spring semester over the three year grant period. Each student will 1) read relevant articles from the peer-reviewed literature to learn about the background of the proposed research, 2) actively participate in the analytical work (at WHOI) associated with the experiments by working in teams, 3) interpret the results as the data is generated, 4) write reports describing the significant scientific results from their analytical team, and 5) contribute to the production of a single manuscript that emulates the format of a journal article. Thus, this RUI grant will provide a unique undergraduate research experience for up to 30 geology students at BSC, making them more competitive applicants to high quality graduate programs and enhancing the likelihood that they will pursue careers in the geosciences. In addition to the research course, this project provides an opportunity for up to 6 undergraduate students at BSC to perform more intensive research in the hydrothermal laboratory at WHOI during the summer months.