Collaborative Research: Do improved absolute plate motion models based on Cretaceous Western Pacific seamounts relate Louisville to Ontong-Java?

合作研究：基于白垩纪西太平洋海山的改进绝对板块运动模型是否将路易斯维尔与翁通爪哇联系起来？

• 批准号: 1912931
• 负责人: Matthew Jackson
• 金额: $ 26.49万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1912931&HistoricalAwards=false
• 关键词: Collaborative; Research; Do; improved; absolute

Earth’s oceans contain a significant number of volcanic structures, many of which remain unexplored and/or unexplained. Some of these structures form chains of progressively older volcanoes, known as seamount trails, which were originally thought to result from Earth’s tectonic plates moving over a fixed “hot” spot in the mantle, producing melt that builds the volcanoes in sequence over time. In the commonly accepted explanation for this volcanic activity, a rising mantle plume delivers material and heat that produce the melt that constructs the volcanoes. In modeling such dynamics, the initial arrival of the plume “head” generates an unusually large amount of melt represented by a large igneous province, while the plume tail generates an age-progressive chain of volcanoes that record the motion of the tectonic plate since the initial eruption of the hotspot. This understanding has led to the fundamental definition of the motions of Earth’s plates. However, in the case of the most voluminous large igneous province - the Ontong-Java Plateau in the western Pacific - a volcanic seamount trail that should be created by a plume tail has not yet been confirmed. The Louisville hotspot has been proposed as a possible candidate hotspot emerging from the Ontong-Java Plateau and generating the Louisville seamount chain, however current models for plate motion suggest a mismatch between the two. A close look at the way plate motion models for the Pacific Plate have been constructed back to the age of the Ontong-Java Plateau (~120 Ma) suggests that some of the volcanic structures, and assumptions used, introduce sufficient uncertainty to merit a reassessment of plate motion models prior to 70 Ma. Alternative plate motion models may allow for a Louisville and Ontong-Java Plateau relationship. This model is testable by studying an alternative hotspot track—with a continuous record of volcanism extending back to 120 Ma—that has recently been recognized. Results have significant implications for understanding tectonic plate motion, as well as the relationship between large igneous provinces and hotspot tracks. This project will have a significant training component for future scientists: the project will include an at-sea rock sampling expedition that will provide seagoing experience to 7 undergraduates from 3 institutions with significant under-represented student populations, 2 graduate students, 1 postdoctoral investigator, and 3 early career scientists. Post-expedition analytical work will define a significant part of the graduate students’ advanced degree work and an important part of the work of one postdoctoral investigator. The primary objective of this study is to improve our understanding of (absolute) plate motion and the relation to and evolution of plume-derived hotspot tracks. In current absolute plate motion models, the time period prior to 70 Ma heavily relies on atypical volcanic structures that do not clearly relate to long-lived hotspot tracks, including: 1) Mid-Pacific Mountains, Line Islands; 2) Shatsky, Hess Rise, Musician Seamounts, Wentworth Seamounts; and 3) Wake Seamounts, Marshall Islands, Magellan Seamounts. Reassessing new and existing data from the Mid- and West-Pacific suggests only the last of these groups may faithfully represent absolute plate motion. A preliminary (based on sparse existing data) absolute plate motion model suggests that these seamounts could be related to the current South Pacific hotspots of Samoa and Rurutu (Arago). In this project, we will test the hypotheses that 1) Wake-Marshall-Magellan relate to Samoa and Rurutu (Arago) hotspots, and that 2) the plate motion model that can be derived from the new data relates Louisville with the Ontong-Java Plateau. These hypotheses will be tested by sampling the Wake-Marshall-Magellan seamounts with a 37-day dredging expedition. Rock samples will be analyzed for their major, trace element and isotopic compositions, and their ages will be determined, in order to properly trace the Samoa and Rurutu (Arago) hotspots into the West Pacific. The resulting hotspot tracks will be used to construct a new (absolute) plate motion model, particularly for the period prior to 70 Ma, and this model will be used to evaluate the potential connection between Louisville and the Ontong-Java Plateau.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.

地球海洋包含大量的火山结构，其中许多是出乎意料和/或未知的。其中一些结构形成了逐渐较旧的火山结构的链条，称为海拔小径，最初被认为是由地球的构造板在地幔中的固定“热”斑点上移动而产生的，从而产生了随着时间的推移构建火山结构的熔体。在对这种火山活动的普遍解释中，地幔上升的李子会提供材料和热量产生构造火山的熔体。在对这种动力学进行建模时，李子“头”的初始到达产生了一个大火成岩省代表的异常大量的熔体，而羽状尾巴产生了一个年龄增强的火山链，这些火山记录了自热点爆发以来最初爆发以来构造板的运动。这种理解导致了对地球盘子动作的基本定义。但是，在西太平洋地区最庞大的大火成岩省（西太平洋的安东 - 贾瓦高原）中，尚未确认应由羽毛尾部创建的火山山脉小径。已提出了路易斯维尔热点作为从Ontong-Java高原出现并产生路易斯维尔海山链的可能的候选热点，但是目前的板运动模型表明两者之间的不匹配。仔细观察太平洋板的板板运动模型已被构造回到安大江高原（〜120 mA）的年龄，这表明某些火山结构和所使用的假设引入了足够的不确定性，值得在70 mA之前重新安排平板运动模型的重新安排。替代板运动模型可能允许路易斯维尔和安大雅瓦高原关系。该模型可以通过研究替代热点轨道进行测试，该轨道的连续记录延伸至120 mA，最近已被认可。结果对理解构造板的运动以及大火成岩和热点轨道之间的关系具有重要意义。该项目将为未来的科学家提供重要的培训组成部分：该项目将包括一次海上岩石采样探险，该探险将为来自3个机构的7位本科生提供海洋经验，其中有重要代表性的学生人数，2名研究生，1名博士后研究员和3名早期职业科学家。后期分析工作将定义研究生高级学位工作的重要组成部分，也是一位博士后研究员的重要组成部分。这项研究的主要目的是提高我们对（绝对）板板运动以及与羽流衍生的热点轨道的关系和演变的理解。在当前的绝对板运动模型中，70 MA之前的时间段重大依赖于与长寿命的热点轨道无明显相关的非典型火山结构，包括：1）中太平洋山脉，线岛； 2）Shatsky，Hess Rise，音乐家的海底，Wentworth Seamounts； 3）唤醒海山，马歇尔群岛，麦哲伦海峡。从中间和西太平洋建议中重新评估新的和现有的数据，只有这些群体中的最后一个可以忠实地代表绝对板运动。初步（基于现有数据稀疏）绝对板运动模型表明，这些海湾可能与萨摩亚和鲁鲁特（Arago）的当前南太平洋热点有关。在这个项目中，我们将测试以下假设：1）与萨摩亚和鲁鲁特（Arago）热点有关的唤醒马歇尔 - 马格兰，以及2）2）可以从与安大哥高原有关的路易斯维尔与新数据相关的板块运动模型。这些假设将通过以37天的挖泥探险来对唤醒马歇尔 - 马格伦海山进行采样。将分析其主要，痕量元素和同位素组合物的岩石样品，并确定其年龄，以便将萨摩亚和鲁鲁特（Arago）热点正确地追溯到西太平洋。由此产生的热点轨道将用于构建一种新的（绝对）板块运动模型，特别是在70 MA之前的时期，该模型将用于评估路易斯维尔与安东尼·贾瓦高原之间的潜在联系。该奖项反映了NSF的法规任务，并认为通过基金会的知识率和广阔的范围来评估，并通过评估诚实地进行了评估。

项目成果

Distinguishing Volcanic Contributions to the Overlapping Samoan and Cook-Austral Hotspot Tracks

区分火山对萨摩亚和库克-澳大利亚热点路径重叠的影响

• DOI: 10.1093/petrology/egac032
• 发表时间: 2022
• 期刊: Journal of Petrology
• 影响因子: 3.9
• 作者: Price, Allison A;Jackson, Matthew G;Blichert-Toft, Janne;Konrad, Kevin;Bizimis, Michael;Koppers, Anthony A;Konter, Jasper G;Finlayson, Valerie A;Sinton, John M
• 通讯作者: Sinton, John M

Hemispheric Geochemical Dichotomy of the Mantle Is a Legacy of Austral Supercontinent Assembly and Onset of Deep Continental Crust Subduction

• DOI: 10.1029/2022av000664
• 发表时间: 2022-12-01
• 期刊: AGU ADVANCES
• 影响因子: 8.4
• 作者: Jackson, M. G.;Macdonald, F. A.
• 通讯作者: Macdonald, F. A.