Collaborative Research: Petrological controls on continental uplift: static- and reactive-transport modeling of hydration-driven de-densification

合作研究：岩石学对大陆隆升的控制：水化驱动去致密化的静态和反应输运模型

• 批准号: 1926096
• 负责人: Richard Palin
• 金额: $ 26.38万
• 依托单位: Colorado School of Mines
• 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 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1926096&HistoricalAwards=false
• 关键词: Collaborative; Research; Petrological; controls; continental

The geological processes that form broad, high-elevation plateaus in otherwise stable and low-lying continental interiors are poorly understood. Yet, such uplift can have profound effects on many aspects of the whole earth system, including atmospheric circulation and biodiversity. Ultimately, the causes of plateau uplift are driven by deep-seated processes within the Earth's crust and lithosphere, but due to inaccessibility, such processes remain enigmatic. A recently proposed hypothesis suggests that the addition of hydrous fluids and/or water to nominally dry lower crust could cause mineral reactions that result in significant changes in density and volume, leading to expansion and therefore surface uplift. However, the magnitude of these changes as functions of rock composition, proportion of fluid added, and depth below the Earth's surface are unquantified. The proposed study addresses this knowledge gap by performing laboratory analysis on rocks collected from the Colorado Plateau, USA, and computational modeling to produce a new predictive toolbox that can constrain the topographic effects of crustal hydration in any geological scenario worldwide. This research will train one new PhD student, two undergraduate students from underrepresented backgrounds, and promote new collaboration between two US-based early-career researchers.The tectonic effects of crustal hydration are poorly understood, owing to the absence of realistic modeling frameworks for quantifying the petrophysical effects of fluid-rock interaction at middle- to lower-crustal metamorphic conditions. This research aims to directly address this issue by employing recently developed algorithms that quantify the evolution of open and closed petrological systems using equilibrium thermodynamics. Both 1-D and 2-D algorithms will be produced that quantify the relationships between pressure, temperature, bulk-rock density, hydration state, and surface uplift, which can be applied to any crustal environment where fluid-rock interaction takes place. This will also address both closed- and open-system geological scenarios, considering small-scale and short-term fluid influx (e.g. crystallizing magmas) to large-scale, continuous fluid influx (e.g. devolatilization of a subducting slab). Predictions made for intercontinental plateau formation will be ground-truthed by measuring mineral compositions and water contents within natural samples exposed from different levels of the Colorado Plateau crust, as determined by electron probe microanalysis, electron backscatter diffraction, and secondary ion mass spectrometry. The results of this work will assist in deciphering the driving force for its uplift during the Cenozoic and the extent to which fluids released from the subducted Farallon slab were partitioned between the intermediate lithospheric mantle and the lower/middle continental crust.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.

在原本稳定和低洼的大陆室内形成广泛，高海拔高原的地质过程知之甚少。然而，这种隆升可以对整个地球系统的许多方面产生深远的影响，包括大气循环和生物多样性。最终，高原隆起的原因是由地壳和岩石圈中深处的过程驱动的，但是由于无法获得，这种过程仍然神秘。最近提出的假设表明，将含水液和/或水添加到名义上干燥的下层外壳可能会导致矿物反应导致密度和体积发生显着变化，从而导致膨胀并因此表面隆升。但是，这些变化的大小是岩石组成的功能，添加的流体比例以及地球表面以下深度的幅度。拟议的研究通过对美国科罗拉多高原收集的岩石进行实验室分析以及计算建模来解决这一知识差距，以产生一个新的预测工具箱，该工具箱可以限制在全球任何地质场景中构成地壳水合的地形效应。这项研究将培训一名新的博士生，两名来自代表性不足背景的本科生，并促进两位基于美国的早期研究人员之间的新合作。由于缺乏量化量化现实的建模框架，地壳水合的构造效应知之甚少流体 - 岩石相互作用在中壳变质条件下的岩石物理作用。这项研究旨在通过采用最近开发的算法来直接解决这一问题，这些算法使用平衡热力学来量化开放和封闭的岩石学系统的演变。将产生1-D和2-D算法，以量化压力，温度，散装岩石密度，水合状态和表面隆升之间的关系，这些关系可以应用于发生流体岩石相互作用的任何地壳环境。考虑到小规模和短期液体流入（例如，结晶岩浆）到大规模连续的流体流入（例如，俯冲板的悬浮）。通过测量来自科罗拉多高原外壳不同水平的天然样品中的矿物质成分和水含量，将对洲际高原形成的预测进行实现，这是通过电子探针微分析，电子反向散射衍射和次级离子质谱法确定的。这项工作的结果将有助于解释在新生代期间其隆起的驱动力，以及从俯冲的Farallon板中释放的流体在中间/中层中的中间/中大陆壳之间分配的。使命，并被认为是通过基金会的知识分子优点和更广泛影响的审查标准通过评估值得支持的。