Testing the Resolution of U-Series Age Constraints: An Application to Volcanic Construction at 9 degrees 50'N EPR

摘要：0623838 （Sims）智力优势：本研究针对洋中脊扩张中心洋壳构造的基本问题。重叠的叶状熔岩流是沿洋脊轴线最常见的地质地形，但相对而言，人们对它们是如何形成的以及在什么时间尺度上形成的知之甚少。该研究利用u系列元素的不平衡来确定在东太平洋隆起附近9-10°n的洋中脊附近的一个井图序列中的叶状熔岩流的年代。流的年代测定可以测试u系列年代测定技术的分辨率及其在解决其他地质问题方面的适用性。这项工作还发展了一种新的、时间约束的火山地层学，揭示了近离轴叶状流的就位顺序。这种地层学将揭示它们就位的机制。年龄限制将用于确定喷发的频率、喷发量和重新表面的速率，所有这些都是模拟海洋扩张中心挤压地壳构造的关键参数。ABE和ALVIN等深海潜水机器人的图像将用于确定地理和地层关系。更广泛的影响：这项工作的更广泛影响包括对马萨诸塞州伍兹霍尔海洋研究所的研究人员、一名研究生和本科生的支持。然而，它的主要影响是在使用多收集器电感耦合质谱仪（MC-ICP-MS）的u系列不平衡技术的灵敏度和准确性的提高。该方法的开发部分将扩大u系列定年法在新近喷发火山岩中的应用范围。

ABSTRACT 0623838 (Sims)Intellectual Merit: This research targets fundamental issues in the construction of ocean crust at mid-ocean ridge spreading centers. Overlapping lobate lava flows are the most common geological terrain along the ocean ridge axis, but relatively little is known about how they form and at what time scales. The research uses disequilibria of U-series elements to date lobate lava flows in a well mapped sequence adjacent to the mid-ocean ridge near the East Pacific Rise at 9-10 degrees N. Dating of the flows enables testing of the resolution of the U-series dating technique and its applicability to address additional geologic problems. The work also develops a new, temporally constrained volcanic stratigraphy revealing the ordering of emplacement of near off-axis lobate flows. This stratigraphy will reveal much about the mechanisms of their emplacement. Age constraints will be used to determine the frequencies of eruptions, eruptive volumes, and resurfacing rates, all of which are critical parameters for modeling the construction of the extrusive crust at oceanic spreading centers. Imagery from deep submergence robotic vehicles such as ABE and ALVIN will be used to determine geographical and stratigraphic relationships. Broader Impacts: Broader impacts of the work include support of researchers, a graduate student, and undergraduate students at the Woods Hole Oceanographic Institution in Massachusetts. Its primary impact, however is in the improvement in sensitivity and accuracy of U-series disequilibrium techniques using multiple collector inductively coupled mass spectrometer (MC-ICP-MS). The methods development component will expand the range of applications of U-series dating for recently erupted volcanic rocks.