Collaborative Research: Using the Rurutu hotspot to evaluate mantle motion and absolute plate motion models

海底火山（即夏威夷皇帝火山链和路易斯维尔火山链）的线性轨迹定义了两个寿命最长的太平洋热点的轨迹。长期以来，这两个热点轨迹一直被用来模拟构造板块运动，并定义大陆是如何随着时间在地球表面移动的。人们普遍认为，起源于地幔深处的热点是固定的，当板块在其上移动时，热点穿过地壳，形成一个线性的火山链，可以用来显示板块在数千万年里运动的速度和方向。然而，现在越来越多的证据表明，热点可能实际上并不是相对于地幔或彼此而言是固定的。为了验证移动热点参考框架的假设，本研究将定义第三个长期存在的太平洋热点轨道——鲁鲁图热点，并将其与夏威夷-皇帝和路易斯维尔链进行比较。将对西太平洋萨摩亚群岛附近的20座海底火山进行取样，并收集熔岩的地球化学分析。放射性衰变产生的氩气将被用来确定火山的年龄。熔岩的化学特征，特别是元素丰度和Sr、Ne、Pb和Hf同位素特征，将用于(1)区分汝如图火山与不相关的火山；(2)确定热点的地球化学指纹和演化。从海底打捞的样品将在船上用激光诱导击穿光谱进行描述和分析。测绘和海洋地球物理数据将被收集并用于指导潜在的疏浚目标。更广泛的影响包括一个强大而庞大的学生培训组成部分，其中三名研究生和10名本科生将出海并密切参与该项目。通过从德克萨斯州的西班牙裔服务机构招募学生，并对他们进行最先进的地球化学分析和数据解释方面的培训，这将有助于建立一支更加多样化的科学队伍。这项研究将促进三个机构之间的机构间合作，并将支持两名早期职业研究者。

Linear tracks of submarine volcanoes (i.e., the Hawaiian-Emperor and Louisville volcanic chains) define the trace of the two longest-lived Pacific hotspots. These two hotspot tracks have long been used to model tectonic plate motion and define how the continents have moved over the face of the globe over time. It has generally been believed that hotspots, which originate deep in the mantle, are fixed and that, as the plate moves over it, the hot spot punches through the crust resulting in a linear chain of volcanoes that can be used to show the speed and direction of plate motion over 10's of millions of years. Mounting evidence now, however, indicates that hotspots may not actually be fixed with respect to the mantle or each other. To test the hypothesis of a moving hotspot reference frame, this research will define a third, long-lived, Pacific hotspot track, the Rurutu hotspot, and compare it with the Hawaiian-Emperor and Louisville chains. Twenty submarine volcanoes near the Samoa Islands in the western Pacific Ocean will be sampled and geochemical analyses of the lavas will be collected. Argon, produced from radioactive decay, will be used to determine the ages of the volcanoes. The chemisty of the lavas, especially the elemental abundances and the Sr, Ne, Pb, and Hf isotopes signatures, will be used to (1) distinguish Rurutu volcanoes from unrelated ones and (2) determine the geochemical fingerprint and evolution of the hotspot. Samples dredged from the seafloor will be described and analyzed on the ship by Laser Induced Breakdown Spectroscopy. Mapping and marine geophysical data will be collected and used to guide potential dredging targets. Broader impacts include a strong and large student training component in which three graduate students and 10 undergraduates will go to sea and be intimately involved in the project. This will help build a more diverse scientific workforce by recruiting students from a Hispanic Serving Institution in Texas and training them in state-of-the-art geochemical analysis and data interpretation. This research will foster inter-institutional collaboration between three institutions and will support two early career investigators.