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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

基本信息

批准号：
1926134
负责人：
Emily Chin
金额：
$ 8.08万
依托单位：
University of California-San Diego Scripps Inst of Oceanography
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 2023-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1926134&HistoricalAwards=false
关键词：
Collaborative Research Petrological controls continental

项目摘要

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.

在其他稳定和低洼的大陆内部形成宽阔的高海拔高原的地质过程鲜为人知。然而，这种抬升可能会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。归根结底，高原抬升的原因是由地壳和岩石圈内的深层过程驱动的，但由于难以接近，这种过程仍然是个谜。最近提出的一种假说认为，将含水流体和/或水添加到名义上干燥的下地壳可能会引起矿物反应，导致密度和体积的显著变化，从而导致膨胀，从而导致地表隆起。然而，这些变化的幅度作为岩石成分、添加的流体比例和地球表面以下深度的函数是无法量化的。拟议的研究通过对从美国科罗拉多高原收集的岩石进行实验室分析和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，可以在世界范围内的任何地质情况下限制地壳水化的地形影响。这项研究将培养一名新的博士生和两名来自代表性较低背景的本科生，并促进两名美国早期职业研究人员之间的新合作。由于缺乏现实的建模框架来量化中、下地壳变质条件下流体-岩石相互作用的岩石物理效应，人们对地壳水化的构造效应知之甚少。这项研究旨在通过采用最近开发的算法来直接解决这个问题，这些算法使用平衡热力学来量化开放和封闭的岩石系统的演化。将产生一维和二维算法，量化压力、温度、整体岩石密度、水化状态和地表隆起之间的关系，这可以应用于任何发生流体-岩石相互作用的地壳环境。这还将处理封闭和开放系统的地质情景，考虑小规模和短期的流体流入(例如结晶岩浆)到大规模的持续流体流入(例如俯冲板块的去挥发作用)。对洲际高原形成的预测将通过测量科罗拉多高原地壳不同层次暴露的天然样品中的矿物组成和水分含量来得到证实，这是由电子探针显微分析、电子背散射衍射和二次离子质谱仪确定的。这项工作的结果将有助于破译新生代期间其抬升的驱动力，以及从俯冲的法拉隆板块释放的流体在中间岩石圈地幔和下/中大陆地壳之间分配的程度。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。