Do seamounts on fossil oceanic spreading centers record triple-junction migration or mantle-plume activity? Guadalupe Island, Mexico as an archetype

化石海洋扩张中心的海山是否记录了三交点迁移或地幔柱活动？

• 批准号: 2236476
• 负责人: Emily Chin
• 金额: $ 40.91万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2236476&HistoricalAwards=false
• 关键词: Do; seamounts; fossil; oceanic; spreading

Volcanism on Earth is usually focused near boundaries between tectonic plates. This occurs at mid-ocean spreading centers or at subduction zones where plates sink. In some cases, though, volcanism occurs within a tectonic plate. While some intraplate volcanism can be explained by upwelling of a mantle plume, most of Earth's intraplate volcanoes are probably not related to a plume despite such volcanoes being widespread. One possible origin may involve transitions occurring between different types of plates. This project investigates intraplate volcanism offshore of the California Borderlands. This region has a complex plate margin history and unusual types of volcanism. The research team will conduct and video-blog fieldwork on Guadalupe Island offshore Baja California. This island is located along a system of failed mid-ocean spreading centers. It is an ideal location to test ideas related to the formation of non-plume, intraplate volcanism. This project will support a postdoctoral scholar and a PhD student. Together with Mexican collaborators, this project will provide educational opportunities, mentoring, and career development for USA and Mexican students. This project investigates the development of seamounts along failed oceanic spreading centers as a symptom of their interaction with convergent margins. When oceanic spreading centers approach subduction zones, the subducting oceanic plate stalls and subdivides into smaller microplates while the convergent margin evolves into a transform margin bounded by migrating triple junctions. The microplates are eventually captured when their convergent margins become transform margins. This terminates decompression partial melting of depleted mantle along their former divergent margins and initiates the development of alkaline, low-degree partial melting of enriched mantle that produces seamounts along their fossil spreading-center margins. Mantle plumes can produce seamounts with similar chemistry and must also be considered as a potential origin for seamount trails such as the Fieberling–Guadalupe seamount chain that intersect fossil spreading centers. The project intends to determine the origin of oceanic Guadalupe Island, which is an alkaline seamount that emerged above sea level ~270 km offshore of Baja California (Mexico) and is situated along a system of failed oceanic rifts that developed offshore of the California borderlands during the late Cenozoic. The project will test four hypotheses that predict different temporal and geochemical patterns for the transition from tholeiitic, mid-ocean-ridge-basalt (MORB) magmatism to alkaline, fossil-spreading-center-seamount magmatism due to triple-junction instability or mantle-plume magmatism. The approach is to integrate field geology, 40Ar/39Ar geochronology, major–trace-element and isotope geochemistry, and petrological modelling. Investigation of seamount petrology and timing within a regional-tectonic framework may therefore reveal geodynamic relationships among mantle flow, mantle melting, triple-junction migration, microplate capture, and/or mantle-plume activity, in addition to improving our understanding of the evolution of western North America during the late Cenozoic.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.

地球上的火山主义通常集中在构造板之间的边界附近。这发生在中海中的中心或板块下沉的俯冲带。但是，在某些情况下，火山板发生在构造板中。虽然可以通过地幔羽流的上升来解释某些板岩火山，但地球内大部分板内火山可能与羽流目的地无关。一种可能的起源可能涉及不同类型的板之间发生的过渡。该项目调查了加利福尼亚州边境境外的板室内火山。该区域具有复杂的板缘历史和不寻常的火山类型。研究小组将在瓜达卢佩岛（Guadalupe Island）近海巴哈（Baja California）进行视频博客实地调查。该岛位于失败的中海中心中心的系统沿线。它是测试与非倾斜，板间火山症形成有关的想法的理想场所。该项目将支持博士后科学和博士生。该项目与墨西哥合作者一起，为美国和墨西哥学生提供教育机会，心理和职业发展。该项目调查了沿海洋扩散中心失败的海山的发展，这是它们与收敛边缘相互作用的症状。当海洋扩散中心接近俯冲带时，俯冲的海洋板摊位和细分变成较小的微板，而收敛的边缘则会通过迁移的三个连接处变成一个变化边缘。当微板的收敛边缘变成变换边缘时，最终将捕获。这终止了沿其前不同边缘的枯竭地幔的部分熔化，并启动了富裕地幔的酒精，低度部分融化的发展，从而沿其化石扩散中心的边缘产生封口。地幔李子可以产生具有相似化学性质的海湾，还必须被视为诸如与化石扩散中心的Fieberling -Guadalupe海山链等海上小径的潜在起源。该项目旨在确定海洋瓜达卢佩岛的起源，这是一个碱性海拔，在海拔约270公里的海平面上，加利福尼亚州巴哈（墨西哥）近海距离海平面约270公里，沿着大海洋裂谷的体系发展，在后期的cenozoic期间，在加利福尼亚州的海上陆地上形成了一个失败的海洋裂谷。该项目将测试四个假设，这些假设可以预测从蒂特利特人，中洋基中部 - 巴萨尔特（Morb）岩浆（Marb）岩浆质量到酒精，化石开放的中心 - 隔离岩浆岩浆岩浆的过渡。这种方法是将田间地质学，40AR/39AR年代学，主要跟踪元素以及对区域建立框架内的海山岩质和时间的研究可能揭示地幔流，地幔融化，三重结式迁移，微板捕获和/或近距离的活动，以及在我们的后期改进我们在远处的后期，我们对我们的理解以及我们对我们的理解以及我们对我们的理解以及我们对我们的深入估计的临时相关的距离可能揭示了地球动力学关系。 Cenozoic。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评论标准来评估的。