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，但我们对底层海皮的下部如何随着时间的流逝而发展，在源自中部山脊中爆发熔岩或通过推力断层或在海洋核心中滚过来的熔岩而变厚和冷却。因为该材料构成了俯冲带消耗到地幔中的地壳中的大部分材料，这是世界上绝大多数地震和火山的基因座，因此了解地壳岩石圈的结构，组成和演变对于科学知识和灾难风险分析都很重要。为了进一步了解有关海角这一部分的更多信息，由国际海洋发现计划的巨大的社区驱动努力，通过国际海洋发现计划钻入海底的岩浆岩石，这是一项涉及世界各地30多位科学家的努力，于2015年至2016年在西南印度山脊上在一个称为Atlantis Bank的印度山脊上进行。这项研究的目标是确定构成下海壳，空间序列及其尺寸的侵入物体的大小，形状和时机。 样品来自最近海洋钻孔腿上钻的核心。还将分析来自一般附近核心的样品，并将其与新孔中的样本进行比较，以了解火成岩侵入物体的空间连续性。 为了实现研究目标，锆石的高精度铀铅（U-PB）年代（一旦形成）矿物质耐药性，将用于对海洋盆地下层岩层积聚期间岩浆主义的时间和空间分布提供见解。如最近的其他研究所示，这些数据允许识别单个侵入性事件，这些事件可以对下海壳的结构维度和历史产生限制，并指示侵入性体的冷却速率。将使用同位素限制热电离质谱法分析了从789米长的核心钻进到亚特兰蒂斯银行的90多个样品。在爱达荷州（博伊西州立大学）的一家姊妹机构将进行有关锆石Hafnium的其他同位素工作。 这项工作的更广泛影响是多方面的，包括在两个EPSCOR州（Wyoming和Boise State University）的两名教职员工和一名研究人员的支持，分别是EPSCOR州（Wyoming和Idaho），其中Epscor表明与其他州相比没有大量联邦支出的州。其他影响包括研究生培训，其中之一是来自中国的交换学生，并免费参与该奖项，怀俄明州和加利福尼亚州的中学和高中宣传，以及开发用于整合U-PB和Trace Element Data的新软件。 该研究也是大型跨国海洋钻探计划的一部分，并涉及大量国际合作。

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