Active Tectonics of the Africa-Eurasia Zone of Plate Interaction in the Western Mediterranean

摩洛哥的构造格局以非洲板块和欧亚板块之间的相互作用为主。目前，努比亚板块相对于欧亚大陆向西北方向移动，导致从摩洛哥的Atlas和Rif山脉到西班牙南部的Btic山脉的复杂碰撞和走滑断层。在这个缓慢的非洲-欧亚板块斜向汇聚的地中海西部地区，GPS对地壳活动形变的量化为大洋俯冲最后阶段和大陆碰撞初期的板块相互作用机制提供了新的约束条件。这项研究将提供减少不确定性的新的GPS板块速度测量，以测试这一神秘的缓慢移动板块边界的相互竞争的构造模型。该项目通过培训博士后研究员和摩洛哥学生，发展一支具有全球竞争力的STEM劳动力队伍，促进预期的社会成果，发展国际合作，并通过扩大GPS网络来加强研究基础设施。这一研究项目将提供必要的新观测，以限制地中海西部板块相互作用地区的地球动力学过程，包括阿尔博兰海和摩洛哥Rif的主动平移和旋转，缩短阿特拉斯高原的横跨和垂直运动，以及西班牙最南端的贝蒂斯山脉的走滑运动。由此产生的大地测量约束将区分相互竞争的构造模式：1)与直布罗陀弧有关的西退；2)俯冲的努比亚板块南退，和/或3)碰撞带内大陆岩石圈的拆沉。该研究小组与来自摩洛哥(国家科学与技术中心、穆罕默德五世大学、阿卜杜勒马利克·埃萨迪大学)、法国(蒙彼利埃大学)和西班牙(阿尔马达真实研究所)的科学家合作，将完善目前的大地形变估计，以更好地约束整个板块相互作用区的地球动力学。该小组将重新观察6个调查地点，将速度不确定度降低30%至50%(水平方向约为0.3毫米/年，垂直方向约为0.7毫米/年)。此外，该小组将在变形速度最大的农村地区建立一个新的连续GPS站，相对于稳定的努比亚，达到约4毫米/年。改进的速度测定对于约束垂直运动和估计RIF的内部变形以及RIF边界构造上的滑动速率是必要的，这些信息对于更好地约束活动断层上的活动变形和地震灾害的机制是必不可少的。将重新观测横跨中、高和反阿特拉斯山脉的GPS勘测点，这将导致速度不确定度降低50%以上(水平方向不到0.3毫米/年，垂直方向不到0.7毫米/年)，首次对垂直运动速率提供大地测量约束，并将跨越高阿特拉斯山脉的主动缩短的上限提高两倍。这些改进的速度对于更好地限制地壳缩短和次地壳动力过程在维持阿特拉斯山脉高海拔中的作用以及与沿板块边界的动态过程的关系是必要的。分析、解释和建模将与国际合作者共同进行。

The tectonic framework of Morocco is dominated by the interaction between the African and Eurasian plates. Presently, the Nubian Plate moves in a northwest direction with respect to Eurasia resulting in complex collision and strike-slip faulting from the Atlas and Rif Mountains in Morocco to the Betic Mountains in southern Spain. GPS quantification of active crustal deformation in this western Mediterranean region of slow, oblique Africa-Eurasia plate convergence provides new constraints on the mechanics of plate interactions during the final stage of ocean subduction and the initial stages of continental collision. This study will provide new GPS measurements of plate velocities with reduced uncertainties to test competing tectonic models for this enigmatic slow-moving plate boundary. The project advances desired societal outcomes through development of a globally competitive STEM workforce by training of post-doctoral fellow and Moroccan students, development of international collaborations, and research infrastructure enhancement by expansion of a GPS network.This research project will provide new observations necessary to constrain geodynamic processes in the western Mediterranean zone of plate interaction, including active translation and rotation of the Alboran Sea and Moroccan Rif, shortening across and vertical motions in the High Atlas, and strike-slip motion in the Betics of southernmost Spain. Resultant geodetic constraints will distinguish between competing tectonic models: 1) westward rollback associated with the Gibraltar Arc; 2) southward rollback of the subducted Nubian plate, and/or 3) delamination of the continental lithosphere within the collision zone. In collaboration with scientists from Morocco (Centre National pour la Recherche Scientifique et Technique, Universite Mohamad V, Abdelmalek Essaadi University), France (Universite Montpellier), and Spain (Real Instituto y Observatorio de la Armada), this research team will refine present geodetic deformation estimates to better constrain geodynamics across the entire zone of plate interaction. The team will reobserve 6 survey sites, reducing velocity uncertainties by 30 to 50% (to about 0.3 mm/year horizontal, 0.7 mm/year vertical). In addition, the team will establish a new continuous GPS station in the Rif where deformation rates are greatest, reaching about 4 mm/year with respect to stable Nubia. Improved velocity determinations are necessary to constrain vertical motions and estimate internal deformation of the Rif, as well as slip rates on Rif bounding structures, information that is essential to constrain better both the mechanics of active deformation and seismic hazards on active faults. GPS survey sites across the the Middle, High, and Anti-Atlas Mountains will be reobserved, which will result in greater than 50% decrease in velocity uncertainties (to less than 0.3 mm/year horizontal, 0.7 mm/year vertical), providing the first geodetic constraints on vertical motion rates and a two-fold improvement on upper bounds on active shortening across the High Atlas. These improved velocities are necessary to better constrain the role of crustal shortening and subcrustal dynamic processes in maintaining the high elevation of the High Atlas Mountains, and the relationship to dynamic processes along the plate boundary. Analysis, interpretation, and modeling will be undertaken jointly with the international collaborators.