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

海底火山的直线轨迹(即夏威夷-帝王和路易斯维尔火山链)定义了太平洋上两个生命最长的热点的轨迹。这两个热点轨迹长期以来一直被用来模拟构造板块的运动，并定义大陆如何随着时间的推移在地球表面移动。人们普遍认为，起源于地幔深处的热点是固定的，当板块在其上方移动时，热点穿透地壳，形成一个线性火山链，可以用来显示S在10‘百万年内板块运动的速度和方向。然而，现在越来越多的证据表明，热点实际上可能不是相对于地幔或彼此固定的。为了检验移动热点参照系的假设，这项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-帝王链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座海底火山进行采样，并收集熔岩的地球化学分析。放射性衰变产生的氩将被用来确定火山的年龄。熔岩的化学性质，特别是元素丰度和Sr、Ne、Pb、Hf同位素特征，将被用来(1)区分鲁鲁图火山和不相关的火山，(2)确定热点的地球化学指纹和演化。从海底挖出的样品将在船上用激光诱导击穿光谱进行描述和分析。将收集测绘和海洋地球物理数据，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部分，其中3名研究生和10名本科生将出海，密切参与该项目。这将通过从德克萨斯州的一家拉美裔服务机构招收学生，并对他们进行最先进的地球化学分析和数据解释培训，帮助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，并将支持两名职业生涯早期的调查人员。

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.