Collaborative Research: Consequences of flat slab subduction on the chemical, structural, and dynamic evolution of continental lithosphere

合作研究：平板俯冲对大陆岩石圈化学、结构和动态演化的影响

• 批准号: 1925939
• 负责人: Thorsten Becker
• 金额: $ 113.8万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1925939&HistoricalAwards=false
• 关键词: Collaborative; Research; Consequences; flat; slab

This project will expand our understanding of how a specific tectonic setting, flat slab subduction, affects the continents on which we live. Flat slab subduction occurs when an oceanic plate that normally descends into the Earth`s mantle at a constant angle of dip changes its geometry and instead sinks only to ~50 miles depth and then travels horizontally for hundreds of miles beneath the continent before returning to the deep Earth`s interior. An episode of flat slab subduction beneath the western United States is believed to be responsible not only for the formation of the Rocky Mountains and the extensive ore deposits of the Colorado Mineral Belt, but also for wide spread explosive volcanism that erupted ~500,000 km3 of silicic magma across the western United States between 36 and 18 million years ago (Mt. St. Helens erupted ~1 km3 for comparison). This volcanism is believed to be due to the effects of the removal of the flat slab and the resumption of a normal subduction geometry, but it has been difficult to study because of the amount of time that has passed since this occurred in the western United States, and because of uncertainty about the geometry of the flat slab that existed before that. In Colombia, there is a unique setting where a once extensive flat slab has split into two parts, one of which remains flat, and one that has comparatively recently foundered and returned to a normal subduction geometry. While this flat slab is much smaller than the one that affected the western United States, the researchers will study the processes responsible for the mountain building, ore deposits, and volcanic hazards in Colombia to gain a better understanding about how continents evolve over time and how these types of volcanic events are related to this specific tectonic environment. This project includes an embedded teacher training initiative led by the Carnegie Academy for Science Education (CASE) which will involve six teachers, two from each PI city (DC, Austin, and Phoenix). Teachers will participate in training, fieldwork, and all-hands meetings throughout the project, and will develop bilingual lesson plans that can be shared through STEM teacher networks. PIs will work closely with the teachers and with CASE in the development of these lesson plans, and will visit teacher classrooms to interact directly with students and to provide feedback. In addition, this project brings together a diverse team that includes two female PIs, and four international collaborators. This research seeks to take advantage of Colombia`s unique tectonic setting to evaluate the effects of flat slab subduction and subsequent foundering on the geochemical, structural, and dynamic evolution of continental lithosphere. Flat slab subduction has been identified along most ocean-continent convergent margins, and has been invoked to explain major tectonic events including the Laramide Orogeny, the evolution of the Altiplano Plateau, and intraplate deformation and volcanism in China. The northern Andes of Colombia provide an ideal location to assess flat slab effects as the retroarc region in central Colombia directly juxtaposes a modern flat slab with a segment that re-steepened over ~4 Ma. The investigators will compare and contrast flat slab and normal subduction, allowing for both across-strike and along-strike comparison of the records of magmatism, crustal structure, lithospheric metasomatism, basin subsidence, and orogenic uplift. To accomplish these objectives, the research team will include multiple disciplines like geochronology, geochemistry, seismology, basin analysis, structure, tectonics, thermochronology, and geodynamics. Project PIs and collaborators will 1) seismically image both the flat and normally dipping slab regions, and the transition between the two, to obtain evidence of the developing and persistent effects of flat slab subduction on the overriding lithosphere; 2) study the magmatic and geochemical effects of flat subduction on the overriding lithosphere through time by analyzing the resulting igneous products, both above the flat slab and along the region of flat slab foundering; 3) investigate the spatial and temporal patterns of subsidence and uplift associated with flat slabs and their foundering through sedimentary and thermochronologic analyses of the Magdalena and Llanos basins and flanking Central and Eastern Cordilleras in both settings, and 4) integrate these constraints into geodynamic models that will improve our understanding of the conditions and parameters that control the dynamics of flat slabs and subduction in general. This award is cofunded by the Prediction of and Resilience against Extreme Events (PREEVENTS) program.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.

这个项目将扩大我们对一个特定的构造环境，平板俯冲，如何影响我们生活的大陆的理解。 当一个海洋板块通常以恒定的倾角下降到地球地幔时，平板俯冲发生改变其几何形状，而不是只下沉到50英里深，然后在大陆下方水平移动数百英里，然后返回地球深处。据信，美国西部下方的一段扁平板块俯冲不仅是落基山脉和科罗拉多矿带广泛矿床形成的原因，而且也是3600万至1800万年前在美国西部爆发约50万立方公里岩浆的广泛爆发性火山活动的原因（Mt.圣海伦斯火山喷发约为1立方公里，以作比较）。 这种火山活动被认为是由于平板的移动和正常俯冲几何形状的恢复所造成的，但由于美国西部发生这种情况以来已经过去了很长时间，并且由于在此之前存在的平板几何形状的不确定性，因此很难进行研究。在哥伦比亚，有一个独特的环境，曾经广阔的平板分裂成两部分，其中一部分仍然是平坦的，另一部分最近已经沉没并恢复正常的俯冲几何形状。 虽然这个平板比影响美国西部的平板小得多，但研究人员将研究哥伦比亚的造山过程，矿床和火山灾害，以更好地了解大陆如何随着时间的推移而演变，以及这些类型的火山事件如何与这种特定的构造环境相关。 该项目包括由卡内基科学教育学院（CASE）领导的嵌入式教师培训计划，该计划将涉及六名教师，每个PI城市（DC，奥斯汀和凤凰城）两名。教师将参加整个项目的培训，实地考察和全体会议，并将制定双语课程计划，可以通过STEM教师网络共享。 PI将与教师和CASE密切合作，制定这些课程计划，并将访问教师教室，直接与学生互动，并提供反馈。 此外，该项目汇集了一个多元化的团队，其中包括两名女性PI和四名国际合作者。这项研究旨在利用哥伦比亚独特的构造环境，以评估板块俯冲和随后的沉没对大陆岩石圈的地球化学，结构和动力学演化的影响。在沿着大多数大洋-大陆会聚边缘都发现了平板俯冲，并被用来解释主要的构造事件，包括拉腊米造山运动、高原的演化以及中国的板内变形和火山活动。哥伦比亚的北方安第斯山脉为评估平板效应提供了理想的位置，因为哥伦比亚中部的弧后区域直接与现代平板并置，其中一个部分重新变陡超过~4 Ma。调查人员将比较和对比平板和正常俯冲，允许横向和沿走向比较岩浆作用，地壳结构，岩石圈交代，盆地沉降和造山隆起的记录。为了实现这些目标，研究团队将包括多个学科，如地质年代学，地球化学，地震学，盆地分析，结构，构造，热年代学和地球动力学。 项目PI和合作者将1）对平坦和正常倾斜的板片区域以及两者之间的过渡进行地震成像，以获得平坦板片俯冲对覆盖岩石圈的发展和持续影响的证据; 2）通过分析由此产生的岩浆产物，研究了平面俯冲对上覆岩石圈的岩浆和地球化学效应，既位于平板上方，又沿着平板下沉区域; 3）通过对马格达莱纳盆地和利亚诺斯盆地以及这两种环境中中部和东部科迪勒拉山脉两侧的沉积和热年代学分析，研究与平板及其沉降相关的沉降和隆起的时空模式，（4）将这些限制因素纳入地球动力学模型，这将提高我们对控制板块和俯冲动力学的条件和参数的理解。 该奖项由极端事件预测和复原力（PREEVENTS）项目共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

The role of flat slab subduction, ridge subduction, and tectonic inheritance in Andean deformation

平板俯冲、山脊俯冲和构造继承在安第斯变形中的作用

• DOI: 10.1130/g50094.1
• 发表时间: 2022
• 期刊: Geology
• 影响因子: 5.8
• 作者: Horton, Brian K.;Capaldi, Tomas N.;Perez, Nicholas D.
• 通讯作者: Perez, Nicholas D.

Plume‐Slab Interactions Can Shut Off Subduction

地幔柱与板片的相互作用可以阻止俯冲作用

• DOI: 10.1029/2022gl099286
• 发表时间: 2022
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Heilman, Erin;Becker, Thorsten W.
• 通讯作者: Becker, Thorsten W.

Mountain building, mantle convection, and supercontinents: revisited

• DOI: 10.1016/j.epsl.2021.116905
• 发表时间: 2021-06
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: C. Faccenna;T. Becker;A. Holt;J. Brun

Timing of hydrocarbon entrapment in the eastern foothills of the Eastern Cordillera of Colombia

哥伦比亚东科迪勒拉东部山麓碳氢化合物滞留时间

• DOI: 10.1190/int-2020-0058.1
• 发表时间: 2021
• 期刊: Interpretation
• 影响因子: 0.3
• 作者: Sánchez, Nelson;Pacheco, Jael;Guzman-Vega, Mario Alberto;Mora, Andrés;Horton, Brian
• 通讯作者: Horton, Brian

Topographic expressions of mantle dynamics in the Mediterranean

• DOI: 10.1016/j.earscirev.2020.103327
• 发表时间: 2020-10-01
• 期刊: EARTH-SCIENCE REVIEWS
• 影响因子: 12.1
• 作者: Faccenna, Claudio;Becker, Thorsten W.
• 通讯作者: Becker, Thorsten W.