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Site Survey for IODP Proposal 646-Full:- Icelandic V-Shaped-Ridges

IODP 提案 646-Full 的现场调查：- 冰岛 V 形山脊

基本信息

批准号：
NE/G001251/1
负责人：
Bramley Murton
金额：
$ 2.42万
依托单位：
NATIONAL OCEANOGRAPHY CENTRE
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FG001251%2F1
关键词：
Site Survey IODP Proposal 646

项目摘要

This Urgency Grant Proposal aims to take advantage of a site survey opportunity in support of a UK-led IODP proposal to drill the North Atlantic basement. A bid made last October to the Science Foundation, Ireland and the Irish Marine Institute by Steve Jones (Trinity Colege, Dublin) and Bramley Murton (NOCS) resulted in 450,0000 euros of ship-time being awarded. The Celtic Explorer has been made available to Jones and Murton between mid-April and mid-May 2008. To support this expedition, funds are sought to mobalise and set-up a portable multibeam exchosounder (Reson 8160), and to hire several dredges from NMFD. The costs are modest, at about 2.5% of the ship-time. The scientific objectives are to map and sample along the strike of a V-shaped ridge that is exposed on the western flank of the Rejkanes Ridge, southwest of Iceland. This Urgency Grant Proposal is in support of a major, UK-led, IODP proposal (646-Full) that addresses fundamental questions about the causes of fluctuations in the activity of volcanic hotspots and their effects on the Earth's environment including climate. Does deep upwelling in the mantle, localized temperature and compositional anomalies, or shallow-mantle flow cause hotspot fluctuations? What are the time scales and rates involved? Where mantle flow is involved, what is its fate as it flows away from a hotspot? To address these issues, we propose to sample time-transgressive features that are common where hotspots interact with mid-ocean spreading ridges. These phenomena are exceptionally clearly developed for the Iceland-Reykjanes Ridge couplet where a series of diachronous V-shaped ridges (VSR's) preserve a record of changing hotspot activity, over the last 35Ma, on the floor of the North Atlantic. Linked to these fluctuations in the Iceland hotspot are variations in the flux of North Atlantic Component Water (NACW) that drives the 'global ocean conveyor' and whose return flow is manifest as the North-Atlantic Drift that moderates the climate of northwestern Europe. The significance of the Iceland VSR's as indicators of the processes of hotspot fluctuations has been recognised in the recent Large Igneous Province IODP Workshop (Colrain, 2007). Sampling the diachronous VSR's by drilling on the flanks of the Reykajnes Ridge in the North Atlantic is the only way to access this geological record. We propose to sample lavas from a transect along one of the youngest VSR's, exposed on the western flank of Reykjanes Ridge. The geochemistry of these lavas will yield insights into the genesis of the VSR's, and hence the causes and processes of hotspot fluctuation. The nature of the questions being addressed and our methodology have been informed from four separate, internationally sponsored workshops over the past 4 years. During the most recent, an UK-IODP workshop 'Rift2Ridge '07', Southampton, 2007, we identified an important link between this proposal and another IODP proposal by Wright et al, (in prep.) that aims to investigate the correlation between the initiation of VSR's on Iceland and fluctuations of NACW overflow strength.

该紧急赠款提案旨在利用现场勘察机会支持英国主导的 IODP 北大西洋基底钻探提案。去年 10 月，Steve Jones（都柏林三一学院）和 Bramley Murton (NOCS) 向爱尔兰科学基金会和爱尔兰海洋研究所提出了投标，最终获得了 450,0000 欧元的航行时间。 Celtic Explorer 已于 2008 年 4 月中旬至 5 月中旬提供给 Jones 和 Murton。为了支持这次探险，我们寻求资金来动员和安装便携式多波束外测深仪 (Reson 8160)，并从 NMFD 租用几台挖泥机。成本较低，约为运输时间的 2.5%。科学目标是沿着冰岛西南部雷卡内斯山脊西侧暴露的 V 形山脊走向进行测绘和采样。这项紧急赠款提案是为了支持英国主导的一项重要的 IODP 提案 (646-Full)，该提案解决了有关火山热点活动波动的原因及其对地球环境（包括气候）影响的基本问题。地幔深处的上升流、局部温度和成分异常或浅地幔流是否会导致热点波动？涉及的时间范围和费率是多少？在涉及地幔流的地方，当它流离热点时它的命运是什么？为了解决这些问题，我们建议对热点与洋中扩张脊相互作用时常见的时间海侵特征进行采样。这些现象在冰岛-雷克雅内斯山脊对联中表现得异常清晰，其中一系列历时的 V 形山脊 (VSR) 保存了过去 35 Ma 中北大西洋海底热点活动变化的记录。与冰岛热点的这些波动相关的是北大西洋成分水（NACW）通量的变化，它驱动着“全球海洋输送带”，其回流表现为北大西洋漂移，调节了欧洲西北部的气候。最近的大型火成岩省 IODP 研讨会（Colrain，2007 年）已经认识到冰岛 VSR 作为热点波动过程指标的重要性。通过在北大西洋雷卡内斯海脊的侧翼钻探来采样历时振动振动频率是获取这一地质记录的唯一方法。我们建议从暴露在雷克雅内斯山脊西侧的最年轻的 VSR 之一的横断面上采集熔岩样本。这些熔岩的地球化学将有助于深入了解 VSR 的起源，从而了解热点波动的原因和过程。过去 4 年举办的四次独立的、国际赞助的研讨会为我们所解决的问题的性质和我们的方法提供了信息。在最近于 2007 年于南安普敦举办的 UK-IODP 研讨会“Rift2Ridge '07”期间，我们确定了该提案与 Wright 等人（准备中）的另一项 IODP 提案之间的重要联系，该提案旨在研究冰岛 VSR 的启动与 NACW 溢出强度波动之间的相关性。