Collaborative Research: Caught in the Act- The Petrology of Modern Lower-Crust Formation and Foundering in the North Andean Arc

合作研究：陷入困境——北安第斯弧现代下地壳形成和沉没的岩石学

• 批准号: 2131643
• 负责人: Mauricio Ibanez-Mejia
• 金额: $ 29.48万
• 依托单位: University of Arizona
• 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: 2021-05-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2131643&HistoricalAwards=false
• 关键词: Collaborative; Research; Caught; Act; Petrology

Earth's continents are thought to have mainly formed in convergent tectonic boundaries, where hydrous fluids transported to depth by subducting plates enable melting of the upper mantle and produce magmas that ultimately contribute to the growth of the overlying crust. Nevertheless, the processes responsible for driving the composition of primitive magmas generated in arc regions, which are basaltic, towards the bulk composition that characterizes Earth's continents, which are andesitic, remain intensely debated. A major difficulty in understanding these 'differentiation' processes, and how they may couple with other first-order features of convergent continental margins, is the fact that the deep roots of these magmatically-active regions are rarely exposed in the Earth's surface. However, volcanic eruptions are sometimes capable of transporting deep-sourced rock fragments - known as 'xenoliths' - to the Earth's surface, providing Earth scientists with unique glimpses of processes occurring deep within the continents that are otherwise difficult to study. In the northern segment of the Andean orogen (southern Colombia), a rare eruption from a recent volcanic vent transported an extraordinary cargo of xenolith fragments sourced from the deep roots of the arc and mantle section beneath it. Therefore, this locality presents a unique opportunity to help unravel the physical and chemical processes that operate during construction of continental crust in magmatically-active regions like the Andes. This award supports two early-career Assistant Professors and a woman who is a PhD student to conduct a detailed geochemical, petrologic and geochronologic study of these unique xenoliths, and the rare eruptions that brought them to the surface. In particular, this research focuses on the 'gravitationally unstable' root of the arc, a section of crustal (i.e., chemically differentiated) rocks with densities greater than the underlying mantle, represented by lithologies such as garnet gabbros, hornblendites, and garnet-bearing pyroxenites. Mechanical removal of density-unstable roots form the base of arcs, a process known as lithospheric foundering (aka, delamination), has not only been identified as a crucial process to explain the chemistry of Earth's continents but is also thought capable of inducing rapid changes in surface elevation, such as those driving the fast Neogene uplift of the Central Andean Plateau. Because the processes taking place in the lower orogenic crust are critical for understanding the uplift history of mountains, the geochemistry of the continents, and the geophysical imaging of the deep lithosphere, results from this investigation will have important implications for our understanding of the geochemical, structural and tectonic history of Andean-type plate margins. In addition to the scientific research products that will result from this investigation, the PIs will collaborate with the Rochester Museum and Science Center (RMSC) on activities that will: 1) explain the origin and physicochemical principles of arc volcanoes to the public of Upstate NY; and 2) continue to organize campus visits for high-school participants of RMSC's 'Next Level Science' summer camps, to provide local students with a direct opportunity to experience college and learn more about upper-level STEM education.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.

人们认为地球大陆主要在收敛的构造边界中形成，在该边界中，通过俯冲板通过俯冲板传递到深度的含液体，使上地幔融化并产生岩浆，并最终有助于上皮地壳的生长。然而，负责推动弧形区域中产生的原始岩浆的组成的过程，它们是玄武岩，朝着代表地球大陆的散装组成的过程，即是安第斯山脉的地球大陆，仍然是激烈的争论。理解这些“分化”过程的主要困难，以及它们如何与收敛大陆边缘的其他一阶特征相结合，这是一个事实，即这些岩浆活性区域的深根很少在地球表面暴露。然而，火山喷发有时能够将深层岩石碎片（称为“异种石”）运输到地球表面，从而为地球科学家提供了独特的在大陆内部很难研究的过程的独特瞥见。在安第斯造山基因（哥伦比亚南部）的北部地区，最近一次火山通风口的罕见喷发运送了来自弧形和地下室深根的异种碎片碎片的非凡货物。因此，该地区提供了一个独特的机会，可以帮助揭开在安第斯山脉（Andes）等岩浆活性地区建造大陆壳期间运行的物理和化学过程。该奖项支持两位早期职业助理教授和一名女性，他们是一名博士生，他们对这些独特的异种石的详细地球化学，质学和地球文学研究进行了详细的地球化学，岩石学和地球学研究，以及将其浮出水面的罕见爆发。特别是，这项研究的重点是弧的“重力不稳定”根，这是一部分（即，化学分化的）岩石，其密度大于基础地幔，以石榴石Gabbros，Hornblendites，Hornblendites和Garnet含糊的Pyroxenites为代表。机械去除密度不稳定的根构成了弧的基础，即一种称为岩石圈基础（又称分层）的过程，不仅被确定为解释地球大陆化学的关键过程，而且还被认为能够诱导表面高度的快速变化，例如那些促进了快速的Neogene neogene neogene the Centrallift of the Centrallift of the Centralean pallift。因为在低再造山壳中发生的过程对于理解山脉的升高历史，大陆的地球化学以及深层岩石圈的地球物理成像至关重要，因此这项研究的结果将对我们对地球化学，结构和构造史的理解具有重要意义。除了这项调查导致的科学研究产品外，PIS还将与罗切斯特博物馆和科学中心（RMSC）合作，讨论：1）将向纽约州北部公众解释ARC火山的起源和物理化学原理； 2）继续为RMSC的“下一个科学”夏令营的高中参与者组织校园访问，为当地学生提供直接体验大学的机会，并了解有关高级STEM教育的更多信息。该奖项反映了NSF的法定任务，并通过评估该基金会的智力功能和广泛的影响来审查NSF的法定任务，并被视为值得通过评估的支持。

项目成果

To sink, or not to sink: The thermal and density structure of the modern northern Andean arc constrained by xenolith petrology

下沉还是不下沉：现代北安第斯弧的热力和密度结构受到捕虏体岩石学的限制

• DOI: 10.1130/g50973.1
• 发表时间: 2023
• 期刊: Geology
• 影响因子: 5.8
• 作者: Zieman, Lisa;Ibañez-Mejia, Mauricio;Rooney, Alan D.;Bloch, Elias;Pardo, Natalia;Schoene, Blair;Szymanowski, Dawid
• 通讯作者: Szymanowski, Dawid

Reading the Isotopic Code of Heavy Elements

解读重元素同位素代码

• DOI: 10.2138/gselements.17.6.379
• 发表时间: 2021
• 期刊: Elements
• 影响因子: 4.5
• 作者: Ibañez-Mejia, Mauricio;Tissot, François L.H.
• 通讯作者: Tissot, François L.H.

Unlocking the Single-Crystal Record of Heavy Stable Isotopes

解锁重稳定同位素的单晶记录

• DOI: 10.2138/gselements.17.6.389
• 发表时间: 2021
• 期刊: Elements
• 影响因子: 4.5
• 作者: Tissot, François L.;Ibañez-Mejia, Mauricio
• 通讯作者: Ibañez-Mejia, Mauricio

Neogene precipitation, vegetation, and elevation history of the Central Andean Plateau

• DOI: 10.1126/sciadv.aaz4724
• 发表时间: 2020-08
• 期刊: Science Advances
• 影响因子: 13.6
• 作者: C. Martínez;C. Martínez;Carlos Jaramillo;C. Jaramillo;A. Correa-Metrio;W. Crepet;J. E. Moreno;A. Aliaga;Federico Moreno;M. Ibáñez-Mejia;M. Bush