Collaborative Research: Structure and Quaternary Kinematics of Amagmatic Rifting in the Central Afar Triple Junction

东非的阿法尔地区包含了唯一一个裂谷-裂谷-裂谷三联点的陆地暴露，因此，为研究从大陆早期分裂到海底扩张的伸展构造作用提供了一个不寻常的机会。现今的阿法尔地区的延伸是由岩浆、轴向裂谷带（红海、亚丁湾和主要的埃塞俄比亚裂谷）和其间的跨该地区的岩浆延伸所容纳的。虽然在该地区进行了大量的地质和地球物理研究，但对如何在这里进行扩展的知识仍然知之甚少。这项研究将通过结构和景观分析、遥感和地质年代学相结合，评估阿法尔裂谷形成的相互竞争的构造模型。对阿法尔裂谷延伸的理解将为裂谷-裂谷-裂谷三结点和大陆裂谷的演化提供一般的见解。该项目将通过代表性不足的少数民族参与STEM，通过HBCU机构的课程增强改善STEM教育，通过培训研究生和本科生发展多元化，具有全球竞争力的STEM劳动力，本研究将研究阿法尔地区的构造和晚新生代构造作用，破译活动裂谷-裂谷-裂谷三联点的新构造格架。亚丁湾和红海裂谷之间的相互作用导致了一个大规模的调节区的发展，目前的特点是半地堑和倾斜的断块在阿法尔中部。了解阿法尔裂谷伸展的划分将提供对裂谷-裂谷-裂谷三结点和大陆裂谷作用演化的一般认识。该研究项目旨在进行实地考察和遥感分析，为估计阿法尔中部调节区部分地区的震级延伸以及第四纪运动学提供依据。阿法尔层状火山岩（4.0？1.0 Ma）是一个区域性的广泛的熔岩表面，早于在阿法尔地堑的启动，因此，提供了一个可行的基准，估计在第四纪的扩展幅度。此外，将长期（第四纪）变形与最近的运动学（例如，从晚更新世地貌和可用的GPS观测）提供了评估调节带的演变的初始手段（例如，同轴应变与渐进应变和旋转）。结合结构和新构造分析，该项目将完成以下工作：（1）限制结构几何形状和恢复区域基准的可行性;（2）估计横跨阿法尔中部部分地区的水平延伸，包括估计小断层对区域应变的贡献;（3）利用构造地貌估计主要断层的晚更新世断层率;（4）利用长期水系演化对无岩浆伸展作用的时空制约。

The Afar region in East Africa encompasses the only on-land exposure of a rift-rift-rift triple junction and, hence, affords an unusual opportunity to study the extensional tectonism from the early break-up of continents to seafloor spreading. Present-day extension across the Afar is accommodated by magmatic, axial rift zones (Red Sea, Gulf of Aden, and the main Ethiopian Rift) and amagmatic extension across the region in between. Although much geological and geophysical research has been conducted in the region, knowledge on how extension is accommodated here remains poorly understood. This study will evaluate competing tectonic models of rift formation in the Afar through a combination of structural and landscape analysis, remote sensing, and geochronology. The resultant understanding of extension across Afar rift will provide insight into the evolution of rift-rift-rift triple junctions and continental rifting, in general. The project will advance desired societal outcomes through participation of underrepresented minorities in STEM, improved STEM education through curricular enhancement at a HBCU institution, development of a diverse, globally competitive STEM workforce through the training of graduate and undergraduate students, and increased partnerships through international collaboration.This study will examine the structure and late Cenozoic tectonism in the Afar region in an effort to decipher the neotectonic framework of an active rift-rift-rift triple junction. The interaction between the Gulf of Aden and Red Sea rifts have led to the development of a large-scale accommodation zone that presently is marked by half grabens and tilted fault blocks in central Afar. Understanding the partitioning of extension across Afar rift will provide insight into the evolution of rift-rift-rift triple junctions and continental rifting, in general. This research project aims to conduct fieldwork and remote-sensing analyses that will provide a basis for estimating the magnitude extension across part of the central Afar accommodation zone, as well as Quaternary kinematics. The Afar Stratoid volcanic rocks (4.0 ? 1.0 Ma) are a regionally extensive lava surface that predates the initiation of grabens in the Afar and, hence, provides a viable datum for estimating the magnitude of extension during the Quaternary. Additionally, comparison of long-term (Quaternary) deformation with more recent kinematics (e.g., from late Pleistocene landforms and available GPS observations) provides an initial means of assessing the evolution of the accommodation zone (e.g., co-axial strain versus progressive strain and rotation). Combining structural and neotectonic analyses, the project will accomplish the following: 1) constrain structural geometries and the viability of a regional datum for restoration; 2) estimate horizontal extension across part of the central Afar, including estimation of the contribution of small faults to regional strain; 3) estimate late Pleistocene rates of faulting for major faults using tectonic landforms; 4) use long-term drainage evolution for spatial and temporal constraints on initiation of amagmatic extension.