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.

地球的海洋包含大量移动的火山结构，其中许多结构尚未被探索和/或无法解释，其中一些结构形成了逐渐古老的火山链，称为海山痕迹，最初被认为是由固定的地球构造板块形成的。在对这种火山活动的普遍接受的解释中，上升的地幔羽流输送了产生的物质和热量。在对这种动态进行建模时，羽流“头部”的初始到达会产生异常大量的熔岩，以大的火成岩省为代表，而羽流尾部则会产生一条记录年龄的火山链。然而，对于体积最大的大型火成岩省来说，这种理解导致了地球板块运动的基本定义。 - 西太平洋的翁通爪哇高原 - 由羽尾形成的火山海山痕迹尚未得到证实，路易斯维尔热点已被提议作为从翁通爪哇高原出现并产生火山喷发的可能候选热点。路易斯维尔海山链，然而，当前的板块运动模型表明两者之间不匹配。仔细观察太平洋板块的板块运动模型的构建方式可以追溯到翁通-爪哇时代。高原（~120 Ma）表明，一些火山结构和所使用的假设引入了足够的不确定性，值得重新评估 70 Ma 之前的板块运动模型。该模型可以通过研究另一个热点轨迹进行测试——火山活动的连续记录可以追溯到 120 Ma——最近人们认识到这一结果对于理解构造具有重要意义。该项目将为未来的科学家提供重要的培训内容：该项目将包括一次海上岩石采样探险，为来自 3 个机构的 7 名本科生提供航海经验。由于学生群体代表性不足，2 名研究生、1 名博士后研究员和 3 名早期职业科学家的探险后分析工作将确定研究生高级学位工作的重要组成部分和一名研究生工作的重要组成部分。这项研究的主要目的是提高我们对（绝对）板块运动以及羽流产生的热点轨迹的关系和演化的理解。在当前的绝对板块运动模型中，70 Ma 之前的时间段严重依赖于板块运动。与长期存在的热点轨迹没有明确关系的非典型火山结构，包括：1）中太平洋山脉、莱恩群岛；2）沙茨基、赫斯海隆、音乐家海山、温特沃斯海山；和 3) 威克海山、马绍尔群岛、麦哲伦海山 重新评估中太平洋和西太平洋的新数据和现有数据表明，只有最后一组可以忠实地代表绝对板块运动（基于稀疏的现有数据）。 ）绝对板块运动模型表明这些海山可能与萨摩亚和鲁鲁图（阿拉戈）当前的南太平洋热点有关。在本项目中，我们将检验以下假设：1)。 Wake-Marshall-Magellan 与萨摩亚和鲁鲁图 (Arago) 热点相关，并且 2) 从新数据中得出的板块运动模型将路易斯维尔与 Ontong-Java 高原联系起来。这些假设将通过对 Wake-Java 高原进行采样来检验。经过 37 天的疏浚考察，将对马歇尔-麦哲伦海山的岩石样本进行主量元素、微量元素和同位素组成的分析，并确定其年龄，以便正确追踪萨摩亚和鲁鲁图（阿拉戈）热点到西太平洋所产生的热点轨迹将用于构建新的（绝对）板块运动模型，特别是70 Ma之前的时期，并且该模型将用于评估。路易斯维尔和翁通爪哇高原之间的潜在联系。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.