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

我们目前对大陆裂谷作用的认识主要是基于对演化和残余裂谷系统的研究。这些研究的观察结果为描述裂谷从开始到破裂的演化提供了动力和约束的数值模型。然而，很少有现场观测能够约束裂谷早期阶段发生的过程以及这些过程的构造控制。这个项目包括一个项目，调查在大陆裂谷的早期阶段发生了什么。东非裂谷系（EARS），由于其靠近旋转极点，在其长度上表现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定位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奥卡万戈裂谷带，那里的经典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完全发育，但岩浆（如果存在的话）尚未突破地表。pi将在ear的西南分支上应用地球物理、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尺度结构和上地幔流动模式。广角地震剖面和重力数据将限制地壳和上地幔结构的变化。大地电磁测量将提供岩石圈薄点和熔体存在的系统尺度约束，而遥感和实地测绘将用于绘制地表变形图。对温泉流体的地球化学分析将确定地幔源熔体的存在。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来发展下一代大陆裂谷模型。

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.