权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Testing the effects of cooling history and rheology on oceanic plateau accretion and their role in tectonic modification of convergent margins

测试冷却历史和流变学对海洋高原增生的影响及其在聚合边缘构造修正中的作用

基本信息

批准号：
2151277
负责人：
Michael Eddy
金额：
$ 57.51万
依托单位：
Purdue University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2022
资助国家：
美国
起止时间：
2022-05-01 至 2026-04-30
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2151277&HistoricalAwards=false
关键词：
Testing effects cooling history rheology

项目摘要

Ocean plateaus are broad and thick volcanic edifices that form in ocean basins. Subduction, the tectonic process in which oceanic crust is pulled back into the Earth’s interior, sometimes causes these plateaus to collide with the continents. The effects of these collisions remain poorly understood and depend on a variety of factors, including the oceanic plateau’s age. Younger plateaus remain warm, buoyant, and weak and resist being pulled into the Earth’s interior, whereas older plateaus are cold, dense, and strong and can more easily be pulled into the Earth’s mantle. The PIs will investigate and compare the effects of ocean plateau collision through an interdisciplinary study of two fragments of the same oceanic plateau that collided with North America at different times. This comparison will provide insights into how the age of an oceanic plateau relates to the collisional process. The proposal will support a female PhD student, several undergraduate researchers, and two early career faculty. It will include a fieldtrip to Washington State for Native American undergraduate students that is designed to connect Earth Science to issues important to Native American communities. This connection is an important step in gaining student interest, recruiting, and training the next generation of Native American Earth scientists.To accomplish the proposed research goals, the researchers will undertake a multi-disciplinary study of two natural examples of oceanic plateau accretion: the Eocene accretion of Siletzia to Washington, Oregon, and Vancouver Island, and the latest Oligocene to present collision of the Yakutat terrane with southern Alaska. The terranes are proposed to have formed as a single plateau and likely have the same crustal structure. However, Siletzia accreted as the plateau was being built while the Yakutat terrane cooled for an additional 30 million years prior to its final collision with southern Alaska. These two collisions provide examples of a collision involving a ‘young, hot, weak, and buoyant’ plateau and one involving a ‘colder, older, stronger, less buoyant’ plateau, respectively. To better understand how each collision modified the convergent margin the PIs will study the syn- and post-collisional sedimentary strata overlying both terranes. This effort will include constructing a precise chronostratigraphy using uranium-lead zircon ID-TIMS (isotope dilution-thermal ionization mass spectrometry) geochronology from interbedded tuffs combined with detailed study of facies changes to better understand how depositional systems evolved during and after each collision. The PIs will also integrate (U-Th)/He (uranium-thorium/helium) zircon thermochronology on targeted detrital zircon populations within the context of their chronostratigraphy to assess the duration and intensity of forearc erosion during each collision. Finally, the investigators will utilize thermo-mechanical models of plateau subduction to help generalize results by systematically varying parameters such as plateau age and thickness. This multidisciplinary approach will provide a more complete understanding of how oceanic plateaus interact with subduction zones, and their role in the modification of convergent margins.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

海洋高原是在海洋盆地中形成的又宽又厚的火山大厦。俯冲作用是海洋地壳被拉回地球内部的构造过程，有时会导致这些高原与大陆发生碰撞。这些碰撞的影响仍然知之甚少，并取决于多种因素，包括海洋高原的年龄。年轻的高原保持温暖、浮力和微弱，抵抗被拉入地球内部，而较老的高原寒冷、稠密和强大，更容易被拉入地球的地幔。pi将通过对同一海洋高原在不同时间与北美碰撞的两个碎片进行跨学科研究来调查和比较海洋高原碰撞的影响。这种对比将有助于我们了解海洋高原的年龄与碰撞过程之间的关系。该提案将支持一名女博士生，几名本科生研究人员和两名早期职业教师。它将包括对美国原住民本科生的华盛顿州实地考察，旨在将地球科学与对美国原住民社区重要的问题联系起来。这种联系是获得学生兴趣、招募和培训下一代美洲土著地球科学家的重要一步。为了完成提出的研究目标，研究人员将对海洋高原增生的两个自然例子进行多学科研究：始新世Siletzia到华盛顿，俄勒冈州和温哥华岛的增生，以及最近的渐新世雅库特地体与阿拉斯加南部的碰撞。这些地体被认为是作为一个单一的高原形成的，可能具有相同的地壳结构。然而，随着高原的形成，西莱齐亚逐渐增加，而雅库特地体在与阿拉斯加南部最终碰撞之前又冷却了3000万年。这两次碰撞分别提供了“年轻、热、弱、有浮力”平台和“更冷、更老、更强、浮力更弱”平台的碰撞例子。为了更好地了解每次碰撞是如何改变收敛边缘的，pi将研究两个地块上的碰撞前后沉积地层。这项工作将包括利用铀-铅锆石ID-TIMS（同位素稀释-热电离质谱法）从互层凝灰岩中建立精确的年代地层，并结合详细的相变化研究，以更好地了解沉积系统在每次碰撞期间和之后的演变。pi还将在年代地层背景下对目标碎屑锆石种群进行(U-Th)/He（铀-钍/氦）锆石热年代学整合，以评估每次碰撞期间弧前侵蚀的持续时间和强度。最后，研究人员将利用高原俯冲的热力学模型，通过系统地改变高原年龄和厚度等参数来帮助推广结果。这种多学科的方法将使我们更全面地了解海洋高原如何与俯冲带相互作用，以及它们在修正辐合边缘中的作用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。