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

摘要0623838（西姆斯）学术成就：这项研究的目标是大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着洋脊轴线最常见的地质地形，但对它们如何形成以及在什么时间尺度上形成的了解相对较少。 这项研究利用U系列元素的不平衡来确定叶状熔岩流的年代，该熔岩流位于靠近东太平洋隆起附近的大洋中脊的一个良好的测绘序列中，北纬9-10度。 流动的年代测定使得能够测试U系列年代测定技术的分辨率及其对解决其他地质问题的适用性。 这项工作还开发了一个新的，时间约束的火山地层揭示了近离轴叶状流的安置顺序。 这种地层学将揭示许多关于它们侵位的机制。 年龄的限制将被用来确定喷发的频率，喷发量，和表面重塑率，所有这些都是关键的参数，在海洋扩张中心的挤压地壳的建设建模。 ABE和ALVIN等深潜机器人潜水器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接收器电感耦合质谱仪（MC-ICP-MS）的U系列不平衡技术的灵敏度和准确度的改进。 方法开发部分将扩大铀系测年法在最近喷发的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.