Geochemical Characterization of Lavas from the 2005-06 EPR Eruption at 9º 50' N: Implications for Magma Genesis, Evolution, and Transport along a Fast Spreading Mid-Ocean Ridge

自2001年被指定为Ridge 2000综合考察点(ISS)以来，东太平洋海隆(EPR)的8°-11°N段已成为全球大洋中脊(MOR)系统最具特征的区域之一。然而，即使在这里，我们对洋脊火山作用的理解也受到了严重限制，因为缺乏关于轴上和轴外单个火山活动的地质、化学和岩石学数据，关于快速扩张中心的空间，特别是时间化学演化的基本问题仍然存在。2005-2006年，EPR ISS(9：47？-54？)内发生了一次海底喷发。N)与文件充分记载的1991-1992年EPR完全相同的地点。这次周期性喷发为拟议的多学科研究提供了一个独特的机会，因为这是山脊地质学家第一次能够在一个可控的时间段(~15年)内评估一个地方的莫尔熔岩地球化学的变化。此外，2005-06年喷发的熔岩的喷发前地震数据、高分辨率填图和高精度的210Po-Pb测年使其成为世界上最好的空间和时间受限的MOR喷发。加上自2006年以来完成的密集熔岩采样，这些数据提供了一个前所未有的机会，可以研究火山喷发的岩石学和地球化学方面，以及伴随这次岩浆事件的时空变化。研究人员将寻找熔岩化学在空间和时间上的系统变化，以及2005-06年喷发的熔岩与1991-92年喷发的熔岩在分离结晶和混合方面的差异。将研究以熔体为宿主的包体，以揭示源熔体透镜中岩浆条件的细节，以及海底以下污染、脱气和水-岩浆相互作用的可能特征。该项目涉及对现有样品的实验室分析，包括同位素、岩石学以及挥发物、卤素和高精度铅同位素的研究。广泛影响：该项目将提供有关EPR岩浆管道系统的岩石学、地球化学和热演化的新的量化信息，对实现Ridge2000计划的目标具有直接和重要的影响，即在东太平洋隆起综合研究场地整合和综合各种数据集的结果。该项目将把两名年轻的科学家带入海洋地质和地球化学领域。首席调查员在过去十年中广泛参与了外展活动，并将继续担任联合首席调查员，以支持和发展佛罗里达大学和里奇2000年的地方和全国教育和外展项目。

ABSTRACTOCE-0819469Intellectual Merit: Since its designation as a RIDGE 2000 Integrated Study Site (ISS) in 2001, the 8°-11° N segment of the East Pacific Rise (EPR) has become one of the best characterized regions of the global mid-ocean ridge (MOR) system. However, even here our understanding of ocean-ridge volcanism has been significantly limited by the lack of geologic, chemical and petrologic data on individual on- and off-axis Fundamental questions remain regarding the spatial and, in particular, the temporal chemical evolution of fast spreading centers. In 2005-06, a submarine eruption occurred within the EPR ISS (9º 47?-54? N) at exactly the same location as the well-documented 1991-1992 EPR. This cyclic eruption provides a unique opportunity for the proposed multidisciplinary study in that it is the first time ridge geologists will be able to evaluate variations in MOR lava geochemistry at one place over a controlled time period (~15 years). Moreover, pre-eruption seismic data, high-resolution mapping and high-precision 210Po-Pb dating of the lavas from the 2005-06 eruption have resulted in its emergence as the best spatially and temporally-constrained MOR eruption in the world. Together with the dense lava sampling completed since 2006, these data provide an unprecedented opportunity to examine the petrologic and geochemical aspects of the eruption as well as the temporal and spatial changes that accompanied this magmatic event.The investigators will search for systematic variations in lava chemistry over space and time, as well as differences in fractional crystallization and mixing between lavas erupted in 2005-06 and those erupted in 1991-92. Melt-hosted xenoliths will be studied to reveal details of the magmatic conditions in the source melt lens, as well as for possible signatures of contamination, degassing and water-magma interactions within the sub-seafloor. The project involves laboratory analysis of existing samples, including isotopic, petrologic and studies of volatiles, halogens and high-precision Pb isotopes.Broader Impacts: This project will provide new quantitative information on the petrologic, geochemical, and thermal evolution of the EPR magma plumbing system, of immediate and significant consequence to achieving Ridge2000 Program goals to integrate and synthesize results across data sets at the East Pacific Rise Integrated Study Site. The project will bring two young scientists into the marine geologic and geochemical field. The principal investigator has been extensively involved in outreach activities over the past decade, and will continue with to co-Principal Investigator to support and develop University of Florida and RIDGE 2000 education and outreach programs both locally and nationally.