Collaborative research: Taking the pulse of the Northwest Hawaiian Ridge: Implications for Flux Variations and mid-Cenozoic Pacific Plate Motions

夏威夷群岛的演化以及大岛上的岩浆活动如何以及为什么会随着时间的推移而变化，对于从科学和实践的角度理解这两个问题都很重要。夏威夷岛是岛链（夏威夷-皇帝岛链）的最新表现，它与地幔中的单一上涌（即地幔柱）有关，地幔柱周期性地向上穿透海洋地壳，将大量熔岩喷发到海底并建造岛屿。夏威夷-帝王链不仅是地幔柱的经典例子，也是已知最热的地幔柱。这个火山柱已经活跃了8000万年，形成了一条从夏威夷到太平洋西北部延伸约6000公里的火山轨迹。尽管这一链条不仅对我们理解地幔柱的起源和演化，而且对构造板块如何随着时间的推移在地球表面移动具有重要意义，但我们对喷发的年龄进程和喷发熔岩沿着链条的化学变化的认识仍然存在重大差距。这项研究分析了从夏威夷-皇帝链西北部沿着的11座火山中新采集的20个岩石样本。这项工作使用最先进的氩-氩测年技术提供了新的年龄，并收集了熔岩的全岩地球化学，以及一套放射性同位素的数据，以确定与喷发有关的地幔温度。这些数据将用于更好地了解夏威夷地幔柱的岩浆演化，以及它的年龄进程如何更好地约束太平洋盆地板块构造。这项工作的更广泛影响包括学生培训和为生物学家提供有关夏威夷本土物种跨越海洋的地理和辐射的更好信息。研究工作的结果将用于与博物馆工作人员合作，为Honoloulu的主教博物馆创建一个关于夏威夷群岛和夏威夷皇帝链的新互动展览。 这为科学提供了一个主要的公共宣传工具，因为主教博物馆每年吸引来自美国和国外的数十万游客。夏威夷-皇帝链是地球上定义最明确的地幔柱，是评估地幔柱相关过程和评估其与板块构造和构造板块运动关系的最佳选择。这项研究使用了来自11座火山的20个新收集的样本，这些样本是在新的美国夏威夷海洋纪念碑中使用遥控车辆进行的一次海洋学考察中收集的，该考察描绘了夏威夷-皇帝链的西北地区。将利用各种各样的观测和分析技术，获得关于这些样品的地球化学和矿物学关系的资料。除了对样品进行岩相学和矿物学检查外，还将收集整个岩石的地球化学数据，以及关于放射性同位素铅、锶、钕和铪的成分和比例的质谱数据。 橄榄石成分也将被确定。这项研究将按照共同标准汇编和纠正该岛链西北部所有已公布的数据，并将其与新数据联合收割机结合起来，建立一个综合的地球化学和年龄数据库，可用于检验该岛链这一部分在新生代期间形成和演变的模型。结果将使用地球化学和地球物理方法进行建模，以提供对地幔柱和板块运动学的基本新见解。新的地球化学数据将被用来确定夏威夷地幔柱源成分的长期演变，并评估是否有系统的变化，地幔温度，熔融压力，和/或源岩性随时间的推移。新的年龄将被用来修改新生代太平洋板块运动和计算差分运动作为代理应力变化沿着岛链随着时间的推移，以评估板块运动对岩浆流量rate.This奖项反映了NSF的法定使命，并已被认为是值得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的支持。

The evolution of the Hawaiian Islands and how and why magmatism on the Big Island changes over time is important to understand both from a scientific and practical point of view. The island of Hawaii is the most recent expression of a chain of islands (the Hawaiian-Emperor Chain) related to a single upwelling in the mantle (i.e. a mantle plume) that periodically punches up through the ocean crust and erupts massive amounts of lava onto the seafloor and builds islands. The Hawaiian-Emperor Chain is not only the classic example of a mantle plume, it is also the hottest known. This plume has been active for 80 million years and has formed a trail of volcanoes extending ~6000 km in length from Hawaii to the northwestern reaches of the Pacific Ocean. Despite the importance of this chain, not only to our understanding of the origin and evolution of mantle plumes but also to how tectonic plates move across the face of the Earth over time, there are still major gaps in our knowledge of the age progression of the eruptions and chemical variations of the erupted lavas along the chain. This research analyzes twenty newly-collected rock samples from eleven volcanoes along the northwestern part of the Hawaiian-Emperor Chain. This work provides new age dates using state-of-the-art argon-argon dating techniques and collects whole-rock geochemistry on the lavas, as well as data on a suite of radiogenic isotopes to determine mantle temperatures associated with the eruptions. These data will be used to better understand the magmatic evolution of the Hawaiian mantle plume and how its age progression better constrains Pacific Ocean basin plate tectonics. Broader impacts of the work include student training and providing biologists with better information about the biogeography and radiation of native Hawaiian species across the ocean. Results of the research work will be used to create a new interactive exhibit on the Hawaiian Islands and the Hawaiian-Emperor Chain for the Bishop Museum in Honoloulu, in collaboration with museum staff. This provides a major public outreach vehicle for science as the Bishop Museum attracts hundreds of thousands of visitors a year from the US and abroad. The Hawaiian-Emperor Chain is the most well-defined mantle plume on the planet and is optimal for evaluating mantle plume related processes and assessing their relationship to plate tectonics and tectonic plate motion. This research uses 20 newly collected samples from eleven volcanoes that were collected on an oceanographic expedition characterizing the northwest region of the Hawaiian-Emperor Chain using remotely operated vehicles in the new US Hawaiian Marine Monument. Information on the geochemistry and mineralogical relationships of these samples will be generated using a wide variety of observational and analytical techniques. In addition to petrographic and mineralogical examination of the samples, whole rock geochemical data will be collected, as will mass spectrometric data on the composition and ratios of the radiogenic isotopes: lead, strontium, neodymium, and hafnium. Olivine compositions will also be determined. The research will compile and correct, to common standards, all published data from the northwest part of this island chain and combine it with the new data to create a comprehensive geochemical and age date database that can be used to test models for this part of the chain's formation and evolution during the Cenozoic. Results will be modeled using geochemical and geophysical approaches to provide fundamental new insights into mantle plumes and plate kinematics. New geochemical data will be used to determine the long-term evolution of the Hawaiian mantle plume source components and to evaluate whether there have been systematic variations in mantle temperature, melting pressure, and/or source lithology over time. The new ages will be utilized to revise Cenozoic Pacific plate motions and to compute differential motions as proxies for stress changes along the island chain with time to evaluate the effects of plate motion on magma flux rate.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.