Collaborative Research: From subduction to suture: testing collisional stage and lithospheric strength as controls on orogenic structure in the Caucasus

合作研究：从俯冲到缝合：测试碰撞阶段和岩石圈强度作为高加索造山结构的控制

• 批准号: 2050618
• 负责人: Nathan Niemi
• 金额: $ 42.48万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2050618&HistoricalAwards=false
• 关键词: Collaborative; Research; subduction; suture; testing

Mountain belts form where two plates that make up the outer-most shell of the Earth (the crust) collide. These collisions are driven by the plate tectonic cycle. Where one colliding plate is composed of dense oceanic crust and the other is more buoyant continental crust, which makes up most of the landmasses on Earth, the oceanic crust sinks back in the Earth’s deep interior via subduction to recycle material from the surface back into Earth’s mantle. However, when the two colliding plates are composed of continental crust, they both resist subduction, resulting in the formation of the largest mountain belts on Earth. The collisions that form these mountain belts produce devastating earthquakes, concentrate natural resources, and drive biological evolution via the rapid growth/decay of topography. Continental collisions often terminate periods of oceanic plate subduction, but much is still not understood about the transition between these two processes, including how a subduction zone converts to a continental collision to produce a mountain chain, what controls the size and locations of large earthquakes, or what modulates the distribution of economically critical ores. This 3-year, international collaboration between researchers at the University of California, Davis, the University of Michigan, and Ilia State University in the Republic of Georgia will investigate the transition from subduction to continental collision in the Greater Caucasus Mountains, a major tectonic element of the Arabia-Eurasia continental collision, and one of the only places Earth where this transition can be observed today. This project will advance scientific knowledge and contribute to society by training PhD students, which contributes to the preparation of a globally competitive STEM workforce and expands the pool of STEM educators. The project will engage and mentor undergraduate students who are from underrepresented minorities, providing professional development and increased participation in STEM, and will increase domestic and international partnerships by engaging US students in collaborative, international work, providing training to graduate students from Ilia State University, deepening collaborations between US and Georgian researchers, and supporting new research collaborations within the US. Finally, this project will enhance research and educational infrastructure by supporting analytical capacities at US research universities.The transition from oceanic subduction to continental collision defines a profound change in force balance and dynamics along the plate boundary. Thus, determining the spatial and temporal distribution of strain during the transition from subduction to collision is critical for relating the deformational response of the orogen to the far-field plate motions driving that deformation. During the transition, buoyant crust of the subducting continental margin enters the trench, reduces the dip of the subduction megathrust, increases plate-boundary coupling, and deforms the overriding plate. The transition from subduction to collision triggers fundamental changes in the spatial distribution and rates of deformation, exhumation, and deposition along the convergent margin as the accretionary wedge evolves into the suture between colliding continental blocks. Geologic observations of the spatial and temporal patterns of deformation during the transition from subduction to collision within an active continental collision zone remain highly elusive, primarily because of a paucity of localities to study this transition. This project will test the idea that the Greater Caucasus serve as a natural laboratory to study the subduction to collision transition by determining if a fundamental along-strike dichotomy in the geology, structure, seismicity, and geodetic shortening results from a transition from active subduction in the eastern part of the range to continental collision and terminal suturing in the west. Specifically, this project will test the hypothesis that there is a terminal suture in the Greater Caucasus, west of ~45°E longitude, that represents a now-subducted oceanic back-arc basin that formerly separated Eurasia to the north from a continental ribbon to the south. East of 45°E, collision has not yet occurred, and the range is dominated by active oceanic subduction. The project has two goals: (1) To illuminate the geologic observations necessary to recognize suturing in ancient continental collisions by describing and quantifying the geologic expression, duration, kinematics, and mechanics of this fundamental change in dynamic state and (2) to capture the deformational response of an orogen to the evolving shift in plate boundary forces associated with the transition from subduction to collision, and thus quantify the relative roles of plate strength and plate boundary coupling in controlling orogenic structure.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

山皮带形成了两个构成地球最外壳（地壳）碰撞的两个板。这些碰撞是由板构造周期驱动的。一个碰撞板由密集的海壳组成，另一个碰撞板组成的连续地壳更加浮动，这构成了地球上大部分的地壳，海洋的外壳通过俯冲俯冲地沉入地球内部，以从地面回收回地球。但是，当两个碰撞板由连续地壳组成时，它们都抗俯冲，导致地球上最大的山带形成。形成这些山地带的碰撞会产生毁灭性的地震，集中自然资源，并通过地形的快速生长/衰减来驱动生物学进化。大陆碰撞经常终止海洋板的俯冲时期，但仍未了解这两个过程之间的过渡，包括俯冲带如何转换为连续的碰撞以产生山脉，是什么控制了大地震的大小和位置，或者是什么模块调制了经济上关键的矿石的分布。加州大学戴维斯大学，密歇根大学和佐治亚州共和国伊利亚州立大学研究人员之间的这项为期3年的国际合作将调查从俯冲到更大高加索山脉的连续碰撞的过渡，这是阿拉伯 - 欧拉西亚 - 欧拉西亚 - 欧拉西亚连续碰撞的主要构造要素，只能在地球上观察到这一过渡的地方。该项目将通过培训博士生来推动科学知识，并为社会做出贡献，这有助于准备全球竞争性的STEM劳动力，并扩大STEM教育者的库。该项目将吸引和指导来自人为不足的少数民族，提供专业发展并增加参与STEM的本科生，并通过让我们的学生参与合作，国际工作，为伊利亚州立大学的研究生提供培训，从而增加国内和国际合作伙伴关系，从而加深我们与我们之间的合作培训，并支持我们内部的新研究。最后，该项目将通过支持美国研究大学的分析能力来增强研究和教育基础设施。从海洋俯冲到连续碰撞的过渡定义了沿板边界的力量平衡和动态的深刻变化。这是确定从俯冲到碰撞过渡过程中应变的空间和临时分布对于将造山带与远场板运动驱动变形的变形反应至关重要的。在过渡期间，俯冲的连续边缘的浮力进入沟槽，减少了俯冲的倾斜量，增加了板块 - 结合耦合，并变形了压倒板。随着积聚楔的发展到碰撞连续块之间的缝合线，从俯冲到碰撞触发的触发触发触发的基本变化和变形，挖掘和沉积速率的基本变化。在主动连续碰撞区域内从俯冲到碰撞的过渡期间，对空间和临时变形模式的地质观察结果非常难以捉摸，首先是由于无法研究这种过渡的地方。该项目将测试以下观点：大高加索是一种自然实验室，通过确定在地质，结构，结构，地震性和地球缩短的基本沿碰撞过渡的俯冲途径中，这是由于范围内部和西部连续碰撞和终端缝合的活性俯冲而产生的。具体而言，该项目将检验以下假设：在〜45°E经度以西的大高加索地区有一个末端缝合线，该假设代表了现已取消的海洋后弧盆地，该盆地先前从欧亚大陆向北分离，从向南的连续色带向北分离。在45°E以东，尚未发生碰撞，并且该范围由主动海洋俯冲支配。该项目有两个目标：（1）通过描述和量化这种动态状态的基本变化的地质表达，持续时间，运动学和机制，以阐明识别古代连续碰撞缝合所必需的地质观察，并量化与骨骼对层的量化相对量的变量，从而捕获了量化的量化和（2）的机制，从而捕获了对层的量化量的变化，从而捕获了量子的量化和（2）的变化。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响标准通过评估来诚实地支持NSF的法定任务。

项目成果

Diverse Deformation Mechanisms and Lithologic Controls in an Active Orogenic Wedge: Structural Geology and Thermochronometry of the Eastern Greater Caucasus

活动造山楔中的多种变形机制和岩性控制：大高加索东部的构造地质学和热测时法

• DOI: 10.1029/2022tc007349
• 发表时间: 2022
• 期刊: Tectonics
• 影响因子: 4.2
• 作者: Tye, A. R.;Niemi, N. A.;Cowgill, E.;Kadirov, F. A.;Babayev, G. R.
• 通讯作者: Babayev, G. R.

Tectonostratigraphy and major structures of the Georgian Greater Caucasus: Implications for structural architecture, along-strike continuity, and orogen evolution

格鲁吉亚大高加索地区的构造地层学和主要结构：对结构体系、沿走向连续性和造山带演化的影响

• DOI: 10.1130/ges02385.1
• 发表时间: 2022
• 期刊: Geosphere
• 影响因子: 2.5
• 作者: Trexler, Charles C.;Cowgill, Eric;Niemi, Nathan A.;Vasey, Dylan A.;Godoladze, Tea
• 通讯作者: Godoladze, Tea