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陆地上唯一的裂谷-裂谷-裂谷三联结，因此，提供了一个不寻常的机会来研究从早期大陆分裂到海底扩张的伸展构造作用。现今横跨阿法尔的延伸是由岩浆、轴向裂谷带（红海、亚丁湾和主要的埃塞俄比亚裂谷）和岩浆延伸所容纳的。尽管在该地区进行了大量的地质和地球物理研究，但对这里如何适应伸展的知识仍然知之甚少。本研究将通过结合构造和景观分析、遥感和地质年代学来评估阿法尔地区裂谷形成的竞争性构造模型。由此产生的对阿法尔裂谷扩展的理解将为裂谷-裂谷-裂谷三联结和大陆裂谷的演化提供洞见。该项目将通过让未被充分代表的少数族裔参与STEM，通过加强HBCU机构的课程来改善STEM教育，通过培训研究生和本科生来培养多样化的、具有全球竞争力的STEM劳动力，以及通过国际合作来加强伙伴关系，从而促进预期的社会成果。本研究将对阿法尔地区的构造和晚新生代构造活动进行研究，以期揭示活跃的裂谷-裂谷-裂谷三联结的新构造格局。亚丁湾和红海裂谷的相互作用导致了阿法尔中部以半地堑和倾斜断块为标志的大规模可容纳带的发育。了解阿法尔裂谷扩展的划分将有助于了解裂谷-裂谷-裂谷三联结和大陆裂陷的演化。这个研究项目的目的是进行实地考察和遥感分析，为估计阿法尔中部可容纳带部分地区的震级扩展以及第四纪运动学提供基础。阿法尔层状火山岩(4.0 ？1.0 Ma)是一个区域性广泛的熔岩表面，早于阿法尔地堑的形成，因此为估计第四纪期间的伸展程度提供了一个可行的数据。此外，将长期（第四纪）变形与最近的运动学（例如，来自晚更新世地貌和可用的GPS观测）进行比较，提供了评估调节带演化的初步手段（例如，同轴应变与渐进应变和旋转）。结合构造和新构造分析，该项目将完成以下工作：1)约束构造几何形状和区域恢复基准的可行性；2)估计阿法尔中部部分地区的水平伸展，包括估计小断层对区域应变的贡献；3)利用构造地貌估算主要断裂的晚更新世断裂速率；4)利用长期排水演化作为岩浆扩张起始的时空约束。

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.