Collaborative Research: Dry Rifting In the Albertine-Rhino Graben (DRIAR), Uganda

合作研究：乌干达艾伯丁-犀牛地堑 (DRIAR) 的干裂谷

• 批准号: 2021692
• 负责人: Robert Evans
• 金额: $ 51.59万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2021692&HistoricalAwards=false
• 关键词: Collaborative; Research; Dry; Rifting; Albertine

The Earth’s surface is constantly moving and changing shape. In some places, like East Africa, a continent stretches to the point of breaking, forming continental rifts that, after a period of time, can form new oceans. Numerous studies show that continental rifts develop along weakened zones caused by deep intrusions of magma. Some continental rifts, however, form without evidence of magma intrusions and are known as magma-poor or "dry" rifts. In this project, an investigation of the East African Rift System will take place along the Northern Western Branch located in Uganda, East Africa where magma-poor rifting is taking place. A wide range of geophysical, geological, and geochemical observations will be collected, and numerical modeling of the region will be performed to advance our understanding of how these magma-poor rifts form and evolve. In conjunction with the scientific investigation, ]Ugandan partners will be engaged in data collection techniques. Ugandan and US graduate students will participate, underrepresented students mentored, and several open-access data sets and model products shall be developed. Societal implications of this study include advances in rifting models used for hydrocarbon exploration, improved estimates of CO2 flux into the atmosphere that occurs during continental rifting, and new insights into seismic hazards associated with active faulting. The scientific results of this project will be communicated, in part, through short educational videos geared towards public audiences. Continental rifting is an integral component of the plate tectonic paradigm, yet speculation remains about the physical processes involved in magma-poor/-dry rifting. The goal of this project is to apply a combination of geophysical, geological, geochemical and geodynamic techniques to the Northern Western Branch of the East African Rift System in Uganda to test 3 hypotheses: (1) in magma-rich rifts, strain is accommodated through lithospheric weakening from melt, (2) in magma-poor rifts, melt is present below the surface and weakens the lithosphere such that strain is accommodated during upper crustal extension, and (3) in magma-poor rifts, there is no melt at depth and strain is accommodated along pre-existing structures such as inherited compositional, structural, and rheological lithospheric heterogeneities. Observational methods in this project include: passive seismic to constrain lithospheric structure and flow patterns; gravity to constrain variations in crustal and lithospheric thickness; magnetics to constrain the thermal structure of the upper crust; magnetotellurics to constrain lithospheric thickness and the presence of melt; GNSS to constrain surface motions, extension rates, and help characterize mantle flow; geologic mapping to document the geometry and kinematics of active faults; seismic reflection analyses of intra-rift faults to document temporal strain migration; geochemistry to quantify mantle-derived fluids in hot springs and gases; and geodynamic modeling to develop new models of magma-poor rifting processes.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.

地球表面正在不断移动和变化。在某些地方，例如东非，连续延伸到破裂的地步，形成连续的裂痕，一段时间后会形成新的海洋。大量研究表明，沿岩浆的深层侵入引起的衰弱区域的持续裂痕。然而，一些连续的裂痕，没有岩浆入侵的证据，被称为岩浆或“干”裂痕。该项目是东非裂谷系统的投资，将在位于东非乌干达的北部西部分支机构进行，那里正在发生岩浆贫困的裂谷。将收集广泛的地球物理，地质和地球化学观测，并将对该区域进行数值建模，以促进我们对这些岩浆贫民窟裂痕的理解和进化的理解。与科学研究结合，乌干达合作伙伴将参与数据收集技术。乌干达和美国的研究生将参加，指导的代表人数不足，并且应开发几个开放式数据集和模型产品。这项研究的社会意义包括用于碳氢化合物勘探的成熟模型的进步，改进了在连续裂开期间发生的二氧化碳通量估计到大气中的估计，以及对与主动断层相关的地震危害的新见解。该项目的科学结果将部分通过针对公众观众的简短教育视频来传达。大陆裂纹是板块构造范式的组成部分，但猜测仍然存在于岩浆贫困/二元成熟中所涉及的物理过程。 The goal of this project is to apply a combination of geophysical, geologic, geochemical and geodynamic techniques to the Northern Western Branch of the East African Rift System in Uganda to test 3 hypotheses: (1) in magma-rich rifts, strain is accommodated through lithosphere weakening from melt, (2) in magma-poor rifts, melt is presented below the surface and weakens the lithosphere such that strain is在上层地壳延伸期间容纳，（3）在岩浆贫困的裂谷中，深度没有熔体和应变，沿着先前存在的结构（例如遗传的组成，结构和流变学岩石圈异质性）容纳。该项目中的观察方法包括：被动地震以限制岩石圈结构和流动模式；重力以限制地壳和岩石圈厚度的变化；磁性限制上皮的热结构；磁纤维素以限制岩石圈厚度和熔体的存在； GNSS限制表面运动，扩展速率和帮助表征地幔流动；地质映射以记录活动断层的几何形状和运动学；裂纹内断层的地震反射分析，以记录临时应变迁移；地球化学以量化温泉和气体中地幔衍生的液体；以及开发岩浆成熟过程的新模型的地球动力模型。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响评估标准，被视为通过评估来获得珍贵的支持。