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.

海洋高原是在海洋鲈鱼中形成的宽阔而厚的火山编辑。俯冲，将海洋壳拉回地球内部的构造过程，有时会导致这些高原与延续相撞。这些碰撞的影响仍然很少理解，并取决于包括海洋高原的各种因素。年轻的高原保持温暖，浮动，弱，抗拒被拉入地球内部，而较老的高原又冷，茂密且坚固，可以更容易地将其拉入地球的地幔中。 PI将通过跨学科研究对海洋高原碰撞的影响进行调查和比较，该研究对在不同时期与北美相撞的同一海洋高原的两个碎片进行了研究。这种比较将提供有关海洋高原关系与碰撞过程的年龄的见解。该提案将支持一位女博士生，几位本科研究人员和两个早期职业教师。它将包括前往华盛顿州的美国原住民本科生的野外渡轮，旨在将地球科学与对美洲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国原住民地球科学家的重要一步。为了实现拟议的研究目标，研究人员将对两个自然的海洋高原积聚例子进行多学科研究：Siletzia的Ecocene Ecoceene insletzia促进了华盛顿，俄勒冈州，俄勒冈州，俄勒冈州和最新的Olastera，并介绍了Colligan的欧洲小家园。提出地层是单个高原形成的，并且可能具有相同的地壳结构。然而，siletzia被接受为高原，而Yakutat Terrane又冷却了3000万年，然后才能更好地了解每次碰撞如何修改PIS将研究的融合边缘研究，并研究了两种地形的合成和后的沉积性Stratta。这项工作将包括使用铀潜在锆石ID-TIM（同位素稀释 - 热电离质量仪）构建精确的年度地层学，并从床上凝灰岩中结合了对设施的详细研究的详细研究，以更好地理解每次碰撞过程中的沉积系统如何演变。 PI还将在靶向碎屑锆石种群上在其年度地层学的背景下整合（铀硫/氦）锆石热量学，以评估每次碰撞过程中前臂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机械模型来通过系统地变化的参数（例如高原年龄和厚度）来概括结果。这种多学科的方法将对海洋高原如何与俯冲区相互作用及其在收敛边缘修饰中的作用提供更完整的了解。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响评估标准来评估值得支持。