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: 1009946
• 负责人: Stephen Gao
• 金额: $ 87.39万
• 依托单位: Missouri University of Science and Technology
• 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 2015-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1009946&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理解主要是基于对演化的和残留的裂谷系统的研究。这些研究的观察结果激励和约束了描述从开始到破裂的裂谷演化的数值模型。然而，很少有现场观测能够限制裂谷作用最早阶段发生的过程以及对这些过程的构造控制。这个项目涉及一个调查大陆裂谷早期阶段发生的问题的项目。东非裂谷系统(EARS)由于靠近自转极，沿其长度显示出强烈的裂谷演化梯度。这为研究驱动裂谷形成和控制早期裂谷局部化的过程提供了一个独特的机会。PIS将对Ears的西南分支进行多学科调查，其中包括非常早期的Okavango裂谷地带，典型的地貌裂谷特征才刚刚开始出现，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)尚未露出地表。PI将在耳朵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来测试这些假设的预测。被动地震数据将约束岩石圈的尺度结构和上地幔流动模式。广角地震剖面与重力数据一起，将限制地壳和最上地幔结构的变化。大地电磁测量将对岩石圈薄点和熔体的存在提供系统规模的限制，而遥感和实地测绘将用于绘制地表形变图。对温泉流体的地球化学分析将确定是否存在地幔来源的熔体。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。