Collaborative Research: Rise and Fall of Galapagos Seamounts

加拉帕戈斯群岛的建筑是独一无二的。 这些岛屿坐落在一个横向延伸的平台上，平台由厚层熔岩流和侵入体组成，这些熔岩流和侵入体高出周围海底3公里。坐在这个平台上，露出水面的是主要的火山岛，这些火山岛构成了达尔文《物种起源》论文的基础。 有趣的是，这些岛屿只占加拉帕戈斯地台体积的5%左右，人们认为加拉帕戈斯地台是由地幔和海洋岩石圈通过起源于地幔深处的热羽流熔融而形成的。 除了火山岛的地表暴露部分，加拉帕戈斯地台的大部分地区仍然没有取样和研究。 最近由达利奥基金会和海洋探索信托基金资助的一次对加拉帕戈斯的海洋学考察绘制了一些主要岛屿之间的部分平台的地图，发现了70个以前不为人知的水下火山建筑物，这些建筑物的表面似乎有波浪切割侵蚀的特征，表明它们的一部分曾经暴露在海平面之上。 在这次探险中收集了150多个岩石样本，希望它们的地球化学成分有助于解开岩浆羽流来源与火山本身化学成分之间的关系。 这一研究项目将分析这些样本，并对最近在加拉帕戈斯巡航考察中收集的测深数据和其他地球物理数据进行更精密的处理，以期更好地了解近期火山活动的历史以及该平台相对于海平面的升降情况。 使用宇宙成因同位素和他的放射性衰变过程中释放，希望显示陆上侵蚀功能的小淹没火山功能的垂直运动可以被定年，并与海平面，热涌由于羽复苏，随着时间的推移和平台沉降。 有待检验的假设包括，审查70座小加拉帕戈斯海山是否各自代表着它们各自进入地幔上涌的岩浆系统，这些岩浆系统与邻近的火山岛不同，彼此也不同。这将通过分析海山样品中的主要和微量元素、Sr、Nd、U和Pb的放射性同位素以及惰性气体来检验。这些数据将用于寻找地球化学的相似性和差异。 在进行这一岩浆源研究的同时，还将对收集到的海底地形进行改进，以研究海山与其地貌特征之间的关系，并确定从海洋中冒出的其他迹象，这可能揭示关于海平面随时间变化的信息。这项工作的更广泛影响包括为联合国教科文组织世界遗产地之一的加拉帕戈斯海洋研究提供关键的地点特征。 由于水下火山大厦是海洋生物和生物多样性的热点，这项工作也为制定加拉帕戈斯受保护的生物遗址特征提供了重要投入。其他影响包括支持一名早期职业教师，该教师的性别在科学领域代表性不足，并且受雇于EPSCoR州爱达荷州的一家机构（即，一个没有得到大量联邦资金的州）;大量的学生培训;以及向公众传播海洋地质学研究的兴奋和奇迹的外联活动。 厄瓜多尔政府将利用地球物理和海底地形研究的结果来评估加拉帕戈斯火山结构可能造成的海啸危险。

The Galapagos Islands are unique in their construction. The islands sit on a laterally extensive platform consisting of thick layered lava flows and intrusions that rises 3 kilometers above the surrounding seafloor. Sitting on this platform and peeking out of the water are major volcanic islands that form the basis of Darwin's treatise on the Origin of Species. Interestingly enough, the islands only comprise about 5 % of the volume of the Galapagos platform, which is thought to have originated by melting of the mantle and oceanic lithosphere via a thermal plume originating deep in the mantle. With the exception subaerially exposed parts of the volcanic islands, much of the Galapagos platform remains unsampled and unstudied. A recent oceanographic expedition to the Galapagos, funded by the Dalio Foundation and the Ocean Exploration Trust, mapped part of the platform between some of the major islands and discovered 70 previously unknown submerged volcanic edifices that appear to sport wave-cut erosional features on their surface, indicating that, once, parts of them were exposed above sea level. Over 150 rock samples were collected on the expedition, with hopes that their geochemistry would help to unravel the relationships between the plume source of magma and the chemistry of the volcanoes themselves. This research project will analyze these samples and provide more sophisticated processing of the bathymetric and other geophysical data that was collected on the recent cruise to the Galapagos in hopes of better understanding the recent volcanic history and the rise and fall of the platform with relation to sea level. Using cosmogenic isotopes and the He that is released during radioactive decay, it is hoped that the vertical movement of the small submerged volcanic features displaying subaerial erosional features can be dated and related to sea level, thermal upwelling due to plume resurgence, and platform subsidence over time. Hypotheses to be tested include examining whether the 70 small Galapagos seamounts each represent their own tapping into the mantle upwelling with magmatic systems that are distinct from the adjacent volcanic islands and each other. This will be tested by analyzing samples from the seamounts for major and trace elements, radiogenic isotopes of Sr, Nd, U, and Pb, and noble gases. These data will be used to look for geochemical similarities and differences. Coupled with this magma source study will be a refinement of the collected seafloor topography to examine relationships between seamounts and their geomorphic features and to identify additional signs of emergence from the ocean, which may reveal information about sea level changes over time. Broader impacts of the work include providing critical site characterization for the Galapagos Marine Research, a UNESCO World Heritage Site. Because the submerged volcanic edifices are hotspots of marine life and biodiversity, this work also provides important input into the development of Galapagos protected biological site characterization. Additional impacts include support of an early career faculty member whose gender is under-represented in the sciences and who is employed at an institution in Idaho, an EPSCoR state (i.e., a state that does not receive significant federal funding); significant student training; and outreach to transmit the excitement and wonder of marine geology research to the public. Results of the geophysical and submarine topographic studies will be used by the Ecuadorian government to assess potential tsunami hazards from Galapagos volcanic structures.