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

西地中海非洲-欧亚板块相互作用带的活动构造

• 批准号: 1419854
• 负责人: Robert Reilinger
• 金额: $ 9.55万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1419854&HistoricalAwards=false
• 关键词: Active; Tectonics; Africa; Eurasia; Zone

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.

摩洛哥的构造格架以非洲板块和欧亚板块的相互作用为主。目前，努比亚板块相对于欧亚大陆向西北方向运动，形成了从摩洛哥的阿特拉斯山脉和里夫山脉到西班牙南部的贝提山脉的复杂碰撞和走滑断裂。在缓慢、倾斜的非洲-欧亚板块汇聚的西地中海地区，GPS对活跃地壳变形的量化为海洋俯冲的最后阶段和大陆碰撞的初始阶段的板块相互作用机制提供了新的约束。这项研究将提供新的GPS测量板块速度，减少不确定性，以测试这个神秘的缓慢移动板块边界的竞争构造模型。该项目通过培养博士后研究员和摩洛哥学生，发展具有全球竞争力的STEM劳动力，发展国际合作，以及通过扩大GPS网络加强研究基础设施，来推进预期的社会成果。该研究项目将提供新的观测结果，以约束西地中海地区板块相互作用的地球动力学过程，包括阿尔博兰海和摩洛哥裂谷的主动平移和旋转，高阿特拉斯的缩短横向和垂直运动，以及西班牙最南端贝提斯的走滑运动。由此产生的大地测量约束将区分不同的构造模式：1)与直布罗陀弧相关的向西回滚；2)俯冲的努比亚板块向南回滚，和/或3)碰撞带内大陆岩石圈的分层。该研究小组将与来自摩洛哥（国家科学研究中心、穆罕默德五世大学、Abdelmalek Essaadi大学）、法国（蒙彼利埃大学）和西班牙（皇家舰队观测研究所）的科学家合作，改进目前的大地测量变形估计，以更好地约束整个板块相互作用区域的地球动力学。该团队将重新观测6个调查点，将速度不确定性降低30 - 50%（水平至0.3 mm/年，垂直至0.7 mm/年）。此外，该小组将在裂谷建立一个新的连续GPS站，那里的变形率最大，相对于稳定的努比亚，每年可达到约4毫米。改进的速度测定对于约束垂直运动和估计裂谷的内部变形以及裂谷边界结构的滑动率是必要的，这些信息对于更好地约束活动变形的力学和活动断层的地震危险是必不可少的。将重新观测横跨中、高和反阿特拉斯山脉的GPS测量站点，这将导致速度不确定性降低50%以上（水平小于0.3 mm/年，垂直小于0.7 mm/年），提供垂直运动速率的第一个大地测量约束，并将高阿特拉斯山脉活跃缩短的上限提高两倍。这些改进的速度对于更好地约束地壳缩短和地壳下动力过程在维持高阿特拉斯山脉高海拔中的作用以及与板块边界动力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。