The Transition from Back Arc to Slab Window to Continental Rifting, Evidence from the Subcontinental Lithospheric Mantle of West Antarctica

从弧后到板窗再到大陆裂谷的转变，来自西南极洲次大陆岩石圈地幔的证据

• 批准号: 2139709
• 负责人: Alberto Saal
• 金额: $ 32.21万
• 依托单位: Brown 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: 2022-03-15 至 2025-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2139709&HistoricalAwards=false
• 关键词: Transition; Back; Arc; Slab; Window

The subcontinental mantle lithosphere is created and modified at plate boundaries through a complex and variable mix of tectonic and magmatic processes that ultimately affect the evolution of the Earth's continents and mantle. The project goal is to evaluate the processes that create, modify, and destroy the subcontinental mantle lithosphere beneath Western Antarctica through the interpretation of a well-integrated set of geochemical and microstructural data from rock samples. The new data will be integrated with already existing seismological observations and geochemistry of erupted basalts. The project will estimate how the composition, structure, mechanical properties, temperature, and foundering potential of the subcontinental mantle lithosphere change along a transect through the Antarctic Peninsula, Jones Mountain, Marie Byrd Land and Ross Island; areas that represent different tectonic and magmatic conditions. This project assesses the geochemistry and microstructure on mantle xenoliths collected in West Antarctica to establish: 1) the xenolith pressure-temperature conditions of the tectono-magmatic events, 2) the variations in the degree of mantle hydration in time and space and its effect on the associated microstructure, 3) the time and source of the subcontinental mantle lithosphere metasomatic agents, 4) the link between mantle xenolith data and the already existing seismological observations and geochemistry of erupted basalts, 5) the effective viscosity of the subcontinental mantle lithosphere and whether the deformation occurred prior to or was affected by the introduction of water and melt, and 6) the contribution of the subcontinental mantle lithosphere into the composition of the erupted basalts across West Antarctica. A key question the project will address is how normal subduction, slab window and continental rifting have produced differences in the inferred density and viscosity structures; and how such difference affected the stability of the subcontinental mantle lithosphere and its potential for ablation by mantle wedge flow, aided by reductions in viscosity due to volatiles and melt, and/or foundering beneath West Antarctica.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.

通过构造和岩浆过程的复杂而可变的混合物在板边界创建并修改了次洲地幔岩石圈，最终影响地球大陆和地幔的演变。项目目标是通过解释从岩石样品中的一组良好集成的地球化学和微观结构数据来评估西南极洲西部下方的次大陆地岩石圈的过程。新数据将与已经存在的地震学观察结果和爆发的地球化学集成在一起。该项目将估算沿着南极半岛，琼斯山，玛丽·伯德·兰德（Marie Byrd Land）和罗斯岛（Ross Island）沿横层沿横层变化的次大陆地岩石圈的组成，结构，机械性能，温度和建立潜力如何变化；代表不同构造和岩浆条件的区域。 This project assesses the geochemistry and microstructure on mantle xenoliths collected in West Antarctica to establish: 1) the xenolith pressure-temperature conditions of the tectono-magmatic events, 2) the variations in the degree of mantle hydration in time and space and its effect on the associated microstructure, 3) the time and source of the subcontinental mantle lithosphere metasomatic agents, 4) the地幔Xenolith数据与已经存在的地震学观察和爆发的底层的地球化学之间的联系，5）5）底部地幔岩石层的有效粘度以及该变形是在水和熔体引入或熔体引入之前还是受到底层的贡献的贡献。该项目将解决的一个关键问题是，正常的俯冲，平板窗口和大陆裂纹如何在推断的密度和粘度结构上产生差异。以及这种差异如何影响次陆地幔岩石圈的稳定性及其通过地幔楔流消融的潜力，这是通过挥发性和融化和/或建立在南极西部西部的粘度下降的帮助，这一奖项反映了NSF的法定任务，并反映了通过评估的范围来弥补的构成师的范围，并构成了奠基型的依据。