Collaborative Research: The four-dimensional distribution of magmatism during the growth of lower oceanic crust: High precision U-Pb dating of IODP Hole U1473A, Atlantis Bank, SWIR

合作研究：下洋地壳生长过程中岩浆活动的四维分布：IODP孔U1473A的高精度U-Pb测年，亚特兰蒂斯浅滩，SWIR

• 批准号: 1636678
• 负责人: Matthew Rioux
• 金额: $ 21.06万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1636678&HistoricalAwards=false
• 关键词: Collaborative; Research; four; dimensional; distribution

Although ocean basins make up over 70% of the Earth's surface, our knowledge of how the lower portions of the underlying ocean crust evolves over time, thickening and cooling after originating as erupting lavas in mid-ocean ridges or via thrust faulting and roll over in oceanic core complexes is poorly known. Because this material makes up the bulk of the down-going portion of the crust consumed into the mantle in subduction zones, which are the loci of the vast majority of the world's earthquakes and volcanoes, understanding the structure, composition, and evolution of this part of the crustal lithosphere is important for both scientific knowledge and disaster risk analysis. To learn more about this part of the ocean crust, a major community-driven effort to drill deep bore holes into magmatic rocks on the seafloor by the International Ocean Discovery Program, an effort involving more than 30 scientists from around the world, was carried out in 2015-2016 on the Southwest Indian Ridge at a location called the Atlantis Bank. Goals of this research are to determine the size and shape and timing of the intrusive bodies that make up the lower ocean crust, their spatial sequence, and their dimensions. Samples come from the core drilled on the recent ocean drilling leg. Samples from a previously drilled core in the general vicinity will also be analyzed and compared to those from the new hole to get an idea of the spatial continuity of the igneous intrusive bodies. To accomplish research goals, high-precision Uranium-Lead (U-Pb) dating of zircons, a mineral resistant to alteration once it is formed, will be used to provide insights into the time and space distribution of magmatism during lower crustal accretion in the ocean basins. As shown by other recent studies, these data permit the recognition of individual intrusive events that can provide constraints on the constructional dimensions and history of the lower oceanic crust and indicate the cooling rates of the intrusive bodies. Over 90 samples from the 789 meter-long core drilled into the Atlantis Bank will be analyzed using isotope-dilution thermal ionization mass spectrometry. Additional isotopic work on Hafnium in the zircons will be carried out at a sister institution in Idaho (Boise State University). Broader impacts of the work are multi-faceted and include support of two faculty and one researcher at institutions (University of Wyoming and Boise State University) in two EPSCoR states (Wyoming and Idaho, respectively) where EPSCoR indicates a state in which there is no significant federal spending compared to other states. Additional impacts include graduate student training, one of whom is an exchange student from China and involved at no cost to this award, middle and high school outreach in both Wyoming and California, and the development of new software for the integration of U-PB and trace element data. The study is also part of the large, multi-national Ocean Drilling Program and involves significant international collaboration.

尽管海洋盆地占地球表面的 70% 以上，但我们对底层海洋地壳下部如何随着时间的推移而演化、在洋中脊喷发熔岩或通过逆冲断层并在海洋中翻转后增厚和冷却的了解。海洋核心复合体鲜为人知。因为这种物质构成了俯冲带中地幔消耗的地壳下行部分的大部分，俯冲带是世界上绝大多数地震和火山的发生地，了解这部分的结构、组成和演化地壳岩石圈的研究对于科学知识和灾害风险分析都很重要。为了更多地了解这部分洋壳，国际海洋发现计划开展了一项由社区推动的重大工作，在海底岩浆岩中钻深孔，这项工作涉及来自世界各地的 30 多名科学家。 2015 年至 2016 年，在西南印度洋山脊的一个名为亚特兰蒂斯浅滩的地方。这项研究的目标是确定构成下洋地壳的侵入体的大小、形状和时间、它们的空间序列和尺寸。 样品来自最近海洋钻探段钻取的岩心。还将分析附近先前钻取的岩心样本，并将其与新钻孔的样本进行比较，以了解火成岩侵入体的空间连续性。 为了实现研究目标，锆石（一种一旦形成就不易蚀变的矿物）的高精度铀-铅（U-Pb）定年将用于深入了解下地壳增生过程中岩浆作用的时间和空间分布。海洋盆地。正如最近的其他研究表明，这些数据允许识别单个侵入事件，这些事件可以对下洋壳的构造尺寸和历史提供限制，并表明侵入体的冷却速率。来自钻入亚特兰蒂斯浅滩的 789 米长岩心的 90 多个样本将使用同位素稀释热电离质谱法进行分析。关于锆石中铪的其他同位素研究将在爱达荷州的姐妹机构（博伊西州立大学）进行。 这项工作的更广泛影响是多方面的，包括来自两个 EPSCoR 州（分别为怀俄明州和爱达荷州）的机构（怀俄明大学和博伊西州立大学）的两名教员和一名研究员的支持，其中 EPSCoR 表示该州没有与其他州相比，联邦支出显着。其他影响包括研究生培训（其中一名来自中国的交换生并免费参与该奖项）、怀俄明州和加利福尼亚州的初中和高中推广活动，以及用于集成 U-PB 和 U-PB 的新软件的开发。微量元素数据。 该研究也是大型跨国海洋钻探计划的一部分，涉及重要的国际合作。

项目成果

Accretion and oxidation of a superfast-spread axial melt lens: TIMS and SIMS zircon analyses of the IODP Hole 1256D gabbros

• DOI: 10.1016/j.lithos.2019.105184
• 发表时间: 2019-12-01
• 期刊: LITHOS
• 影响因子: 3.5
• 作者: Hayman, Nicholas W.;Rioux, Matthew;Schmitz, Mark
• 通讯作者: Schmitz, Mark