Collaborative research: Integrated studies of early stages of continental extension: From incipient (Okavango) to young (Malawi) rifts

合作研究：大陆扩张早期阶段的综合研究：从初期（奥卡万戈）到年轻（马拉维）裂谷

• 批准号: 1009839
• 负责人: Roger Buck
• 金额: $ 27.39万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-05-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1009839&HistoricalAwards=false
• 关键词: Collaborative; research; Integrated; studies; early

Our current understanding of continental rifting is largely based on studies of evolved and relict rift systems. Observations from these studies have motivated and constrained numerical models that describe rift evolution from initiation to rupture. However, there are very few field observations that constrain processes occurring at the earliest stages of rifting and the structural controls on these processes. This project involves a project to investigate the question of what happens in the early stages of continental rifting. The East African Rift System (EARS), because of its proximity to the pole of rotation, exhibits a strong gradient in rift evolution along its length. This provides a unique opportunity to investigate the processes that drive rift initiation and control early rift localization. The PIs will undertake a multidisciplinary investigation of the southwest branch of the EARS, which includes the very early stage Okavango Rift Zone, where classic geomorphic rift features are just beginning to emerge, and the Mweru, Luangwa (Zambia) and Malawi Rifts, where geomorphic features are fully developed but magma (if present) has yet to breach the surface. The PIs will apply a combination of geophysical, geological, geochemical and geodynamic techniques across the southwest branch of the EARS to test the predictions of those hypotheses. Passive seismic data will constrain lithospheric-scale structure and upper-mantle flow patterns. Wide angle seismic profiling, along with gravity data, will constrain variations in crustal and uppermost mantle structure. Magnetotelluric measurements will provide system-scale constraints on lithospheric thin spots and the presence of melt, while remote sensing and field mapping will be used to map surface deformation. Geochemical analysis of hot spring fluids will identify the presence of mantle-derived melts. Geodynamic modeling will synthesize the new geophysical observations and geochemical results to develop the next generation of continental rifting models.

我们目前对大陆裂谷作用的认识主要是基于对演化裂谷系统和残余裂谷系统的研究。从这些研究的观察动机和约束的数值模型，描述裂谷从启动到破裂的演变。然而，有很少的现场观察，约束过程发生在裂谷的最早阶段和这些过程的结构控制。该项目涉及一个研究大陆裂谷早期阶段发生了什么的项目。 东非裂谷系（EARS），由于其接近旋转极，表现出强烈的梯度裂谷演化沿着其长度。 这提供了一个独特的机会，调查的过程，驱动裂缝的启动和控制早期裂缝本地化。 研究所将对EARS的西南分支进行多学科调查，其中包括非常早期的奥卡万戈裂谷带，那里的典型地貌裂谷特征刚刚开始出现，以及Mweru、Luangwa（赞比亚）和马拉维裂谷，那里的地貌特征已经充分发育，但岩浆（如果存在的话）尚未突破地表。 PI将在EARS的西南分支应用地球物理、地质、地球化学和地球动力学技术的组合，以测试这些假设的预测。 被动地震数据将制约岩石圈尺度结构和上地幔流动模式。 广角地震剖面与重力资料沿着，将制约地壳和上地幔结构的变化。 大地电磁测量将提供系统范围的限制岩石圈薄点和熔体的存在，而遥感和实地测绘将被用来映射表面变形。对热泉流体的地球化学分析将确定是否存在幔源熔体。地球动力学模拟将综合新的地球物理观测和地球化学结果，以开发下一代大陆裂谷模型。