Lau Basin Vent Deposit Morphology and Composition: Links to Geologic Setting and Vent Fluid Chemistry

劳盆地喷口沉积物形态和成分：与地质环境和喷口流体化学的联系

• 批准号: 1038135
• 负责人: Margaret Tivey
• 金额: $ 23.49万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1038135&HistoricalAwards=false
• 关键词: Lau; Basin; Vent; Deposit; Morphology

Intellectual merit - Vent deposits are intimately linked within paths of energy and mass transport from the mantle and crust to the oceans and provide habitats for biota. Deposit composition and morphology are linked to the composition and temperature of vent fluids, and to structural aspects of the geologic setting that control the delivery of fluids to the seafloor. In some deposits, incorporation of organisms and/or their products affects deposit evolution. Through their mineral compositions and textures the deposits, which range in age from days to hundreds of years, serve as recorders of past geologic, hydrothermal and biological activity. The goal of this proposal is to use detailed mineralogical data and textural observations combined with geochemical data (from both deposits and fluids) and geochemical modeling of transport and reaction, to determine the formation and evolution of deposits at 6 vent fields along the East Lau Spreading Center/Valu Fa Ridge. It builds on recent published work for the Lau Integrated Study Site (ISS), including information about along-axis trends in composition of the igneous substrate, vent fluid chemistry, and relationships between tectonics, volcanism and hydrothermal activity (Ferrini et al., 2008; Bezos et al., 2009; Escrig et al., 2009; Mottl et al., accepted). Initial characterization of deposits recovered in 2005 has been done, with deposit descriptions and locations relative to geologic features in Ferrini et al. (2008), and with geochemical and XRD analyses released and available through the Marine Geosciences Data System (MGDS). In 2009, additional samples were recovered (including from the recently discovered Tahi Moana vent field), filling gaps in the sample set collected in 2005, resulting in an excellent full suite of representative vent deposit samples from each vent field. Study of this sample set, and integration and synthesis of resultant data with information on geologic settings and vent fluid chemistry, will allow testing of a number of hypotheses that have been developed over the years about seafloor vent deposit formation. The gradient in the composition of the volcanic substrate and vent fluid chemistry from north to south, combined with the pronounced differences in vent fluid chemistry at the southernmost Mariner vent field, allows testing of hypotheses about extents to which deposit composition, morphology, and evolution are affected by 1) volcanic substrate composition, and 2) input of magmatic volatiles (which can result in very low pH vent fluids). Resulting models of vent deposit formation at Lau vent fields will be compared to models developed for other well-described seafloor vent deposits. Of particular interest is that the study of the vent deposits along the Lau ISS, given the range in geologic settings and vent fluid chemistry, will allow comparisons to be made globally between vent fields that exhibit many similarities, and that differ mainly with respect to a single parameter (e.g., depth or volcanic substrate composition or fluid pH or fauna). In addition to testing specific hypotheses, results of this proposal will provide important information on conditions within and on surfaces of deposits, relative fluxes of low temperature vs high temperature flow, extents to which biological activity affects deposit growth, and extents to which biological activity is recorded in the deposits. Broader Impact -This project will provide training and support for a graduate student, and opportunities for undergraduate students through the WHOI summer student fellow program. The PI will continue the types of outreach she has done in the past, including writing papers for and giving lectures to general audiences. The results of the project will be made available to the community through conferences, workshops and publications, and by submitting data and model results to the MGDS/Ridge2000 Data Portal.

智力优点 - 排气矿床与从地幔和外壳到海洋的能量和大规模运输的路径紧密相连，并为生物群提供栖息地。沉积物组成和形态与排气流体的成分和温度以及控制液体向海底传递的地质环境的结构方面有关。在某些沉积物中，掺入生物和/或其产品会影响存款的演变。通过它们的矿物质成分和质地，年龄从天数到数百年的沉积物充当了过去地质，水热和生物学活性的记录。该提案的目的是使用详细的矿物学数据和纹理观察结果，结合了地球化学数据（来自沉积物和流体）以及运输和反应的地球化学建模，以确定沿东LAU扩散中心/Value Fa Ridge的6个通风口田地的沉积物形成和演化。它建立在LAU综合研究地点（ISS）的最新发表的基础上，包括有关轴轴的趋势的信息，这是点燃基质的组成，排气流体化学的组成以及构造学，火山主义和水热活动之间的关系（Ferrini等，2008； Bezos等，2009； Bezos等，2009； Escrig，2009; Escrig et al。在Ferrini等人的地质特征中，已经完成了2005年回收的沉积物的初始表征。 （2008年），并通过海洋地球科学数据系统（MGD）发布并获得地球化学和XRD分析。在2009年，回收了其他样品（包括从最近发现的塔希莫阿纳（Tahi Moana）通风口田中），填补了2005年收集的样品集中的空白，从而从每个通风口场中提供了出色的全套代表性通风矿床样品。对该样品集的研究，以及所得数据与地质环境和排气流体化学的信息的整合和合成，将允许测试多年来开发的有关海底通风量形成的许多假设。火山基底物和排气流体化学从北到南的组成的梯度，再加上最南端水手排气场的通风流体化学的明显差异，允许测试有关延伸的假设，对沉积物组成，形态和进化的延伸量受到量化的影响。将最终的在LAU通风田中形成的排气矿床形成模型将与针对其他描述的海底通风孔沉积物开发的模型进行比较。特别感兴趣的是，鉴于地质环境和排气流体化学的范围，对沿LaU IS的排气沉积物的研究将允许在表现出许多相似之处的通风场之间进行比较，并且在单个参数（例如，DEPTH或火山基底物组成或流体pH或FAUNA）方面的比较主要差异。除了测试特定的假设外，该提案的结果还将提供有关沉积物内外情况的重要信息，低温与高温流量的相对通量，生物学活动影响沉积物生长的范围以及在沉积物中记录生物学活性的范围。更广泛的影响力 - 该项目将为研究生提供培训和支持，并通过Whoi Summer学生会计划为本科生提供机会。 PI将继续她过去所做的外展类型，包括为普通观众撰写论文和演讲。该项目的结果将通过会议，研讨会和出版物以及将数据和模型结果提交MGDS/Ridge2000数据门户提供给社区。