Constructing a 1.5-million-year time series of magmatic and hydrothermal activity at the Juan de Fuca ridge

构建胡安德富卡海岭 150 万年的岩浆和热液活动时间序列

• 批准号: 2323102
• 负责人: Charles Langmuir
• 金额: $ 25.58万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-01-01 至 2027-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2323102&HistoricalAwards=false
• 关键词: Constructing; 1.5; million; year; time

Ocean ridges are the sites of 80% of Earth’s volcanism. These features emit carbon dioxide and exert an important control on the chemical composition of the oceans through deep sea hot springs. The volcanoes are aligned along the 60,000 kilometer long ocean ridge system, where plates spread apart to create the sea floor. Studies of these volcanoes have been restricted to recent volcanic activity, because as the plates spread apart the volcanoes are covered by sediment and become inaccessible. For this reason, there is a present day snapshot of ocean ridge volcanism, but little possibility to study how it varies with one of the most important parameters of Earth science—time. Many aspects of geological phenomena cannot be understood without knowledge of their variations through time, called “time series”. For example, time series of climate show that that Earth passes into and out of ice ages, and that global warming is happening. New discoveries now permit the construction time series for ocean ridges by taking sediment cores along transects perpendicular to ocean ridges. The cores will be used to study volcanic glass that is preserved in the sediment. In particular, the time series will allow tests of the hypothesis that ice age cycles may influence cycles of ocean ridge volcanism and associated hydrothermal activity. Cruises to the Juan de Fuca ridge just off the coasts of Oregon and Washington will permit time series of one million years or more to be obtained for the first time. This project will provide support for undergraduate students to participate in the research cruise. In addition, the project will support an international conference and contribute to a museum exhibit at the Harvard Museum of Natural History.The European Research Council (ERC) has awarded a research grant for the scientific analyses to investigate time-series of ridge processes through a systematic coring program along transects perpendicular to the Juan de Fuca Ridge. The ERC grant to four principle investigators (three at GEOMAR in Germany and one at Harvard) did not include funding for collecting the sediment cores at sea. This proposal funds the ship time to obtain the necessary samples. A preliminary 11 day leg with the AUV SENTRY will obtain sediment thickness as well as high resolution bathymetry to guide the coring. Then, a 21 day leg will carry out 70 cores on three transects, two to the west of the ridge at different distances from the ridge transform intersection, and one to the east. The cruise would produce the first continuous, co-registered time series of glass compositions, hydrothermal activity and bathymetry over the 0 to 1Ma time scales. Time-series of basalt and sediment compositions at ocean ridges have been inaccessible because sea floor is rapidly covered by sediment and basalts are altered or have low potassium contents, making dating problematic. The 104-106 year time scale in particular is central for testing a host of hypotheses for mid-ocean ridges, from the existence and time scales of tectonic/magmatic cycles, to the continuity of magma chambers and hydrothermal systems, to possible relationships between glacial cycles and ridge processes since the Pleistocene. Preliminary data from cores near the ridge axis show that each core is likely to preserve 50-100ka time series of fresh glasses with interesting variations. Closely spaced cores will be used to obtain overlapping time series with the aim of constructing a long a continuous time series back to one million years. The Juan de Fuca region has the benefit of previous cores that show robust age models are possible. The program includes sediment geochemistry for age models and hydrothermal activity, major and trace elements of glasses, radiogenic isotope analyses, volcanological evaluation, modeling of mantle melting, and quantitative statistical and time-series modeling. This program holds the promise of opening new frontiers of time and methodology that may have far-reaching implications for the investigation and understanding of ocean ridges. Broader impacts include training multiple graduate students and post-docs in state of the art techniques, education and participation of Harvard undergraduates on the cruises, an international conference on interactions between glacial cycles and solid earth processes, and an exhibit at the Harvard Natural History Museum which receives more than 250,000 visitors per year including many K-12 students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

海脊是地球火山症80％的地点。这些特征发出二氧化碳，并通过深海温泉对海洋的化学成分产生重要控制。火山沿着60,000公里长的海岭系统对齐，在那里盘子分开以创建海底。对这些火山的研究仅限于最近的火山活动，因为随着板的分开，火山被沉积物覆盖并变得无法接近。因此，当今海洋岭火山的快照，但很少有研究其如何随地球科学的最重要参数之一而变化的可能性。如果没有随着时间的流逝，地质现象的许多方面就无法理解，称为“时间序列”。例如，气候的时间序列表明，地球传递到冰河时代，并且正在发生全球变暖。现在，新发现允许通过沿垂直于海脊的横断面将沉积物核心的岩石芯进行施工时间序列。核心将用于研究保存在沉积物中的火山玻璃。特别是，时间序列将允许测试冰期周期可能影响海岭火山和相关氢活性的循环的假设。在俄勒冈州和华盛顿的费用下，前往胡安·德福卡岭（Juan de Fuca Ridge）将首次获得一百万年或更长时间的时间序列。该项目将为本科生参加研究巡游提供支持。此外，该项目将支持国际会议，并为哈佛大学自然历史博物馆的博物馆展览做出贡献。欧洲研究委员会（ERC）已为科学分析提供了一项研究赠款，以通过沿垂直于Juan de Fuca de Fuca Ridge的骨骼沿骨骼沿骨骼沿骨骼进行系统的Coring程序来研究Ridge流程的时间序列。 ERC赠款给四名主要调查人员（德国的Geomar，一名在哈佛大学）不包括用于在海上收集沉积物核心的资金。该提议为船舶提供了获得必要样本的时间。带有AUV哨兵的初步11天的腿将获得沉积物厚度以及高分辨率的测深度，以引导加油。然后，一条21天的腿将在三个样带上进行70个核心，在山脊西部有两个侧面，距离山脊变换交叉路口不同，另一个在东部。巡航将在0至1MA时尺度上产生第一个连续的，共同注册的玻璃成分，水热活动和测深的时间序列。玄武岩和沉积物成分的时间序列是无法接近的，因为海底被沉积物迅速覆盖，玄武岩被改变或含钾含量低，使约会的问题变得有问题。尤其是104-106年的时间尺度，对于从构造/岩浆周期的存在和时间尺度到岩浆室和氢化体系统的连续性到冰川周期和山脊过程之间可能的关系，从构造/岩浆循环的存在和时间尺度到冰川环境之间可能的关系。脊轴附近核心的初步数据表明，每个核心都可能保留50-100ka时间序列的新鲜眼镜，并具有有趣的变化。紧密间隔的核心将用于获得重叠的时间序列，目的是构建一个长期的连续时间序列回到一百万年。胡安·德福卡（Juan de Fuca）地区的好处是以前的核心，表现出强大的年龄模型。该程序包括用于年龄模型和氢气活动的沉积物地球化学，玻璃的主要和微量元素，放射性同位素分析，火山学评估，地幔熔化的建模以及定量统计以及时间序列建模。该计划的承诺是开放时间和方法的新领域，这可能对海脊的投资和理解具有深远的影响。更广泛的影响包括培训多个研究生和在艺术技术的培训后，哈佛大学上学的教育和参与巡航，冰川周期和固体地球过程之间的互动国际会议，以及哈佛自然历史博物馆在哈佛自然历史博物馆举行的展览，每年都有超过250,000的访客，包括许多K-12的奖项，包括许多K-12学生奖励。基金会的智力优点和更广泛的影响评论标准。