Testing a New Model of the Tertiary Evolution of the Colorado Plateau Based on Constraints from Magmatic Patterns, Xenoliths, Geologic, and Geophysical Data

该项目综合了科罗拉多高原构造和地貌演化的现有数据，以检验该地区第三纪历史的地球动力学模型。这个模型的核心思想是科罗拉多高原是由成分不同的地幔岩石圈构成的，而地幔岩石圈的玄武岩成分是枯竭的。在这种情况下，岩石圈固有的化学浮力可能解释了科罗拉多高原神秘的构造一致性和稳定性。通过比较来自许多不同数据集的数值模型结果约束，正在探索这一想法的地球动力学意义，这些数据集包括：第三纪岩浆模式、热流、地震速度变化、捕虏体、岩石折返以及岩石和地表隆起。这项研究包括明确考虑科罗拉多高原边缘和中部可能存在的不同构造历史。该项目的主要目标是阐明科罗拉多高原第三纪演化中最令人困惑的两个方面--当强烈的岩浆作用和活跃的变形影响美国西部其他地区时，它的岩石和地表隆起的时间和机制，以及它的相对构造稳定性。科罗拉多高原抬升的机制和时间是一个长期存在的谜题，挑战了一些最好的地质学家，包括J.W.鲍威尔、C.达顿和G.K.吉尔伯特。该项目对该地区的历史发展了一种新的看法，即科罗拉多高原的抬升与北美板块的化学结构密切相关，并受到强烈的加热和火成活动的控制，自从俯冲在其下方的法拉隆板块被移除以来，这些活动影响了该板块。这一想法将使用基于物理的模型进行测试，并将结果与来自一系列学科的观察结果进行比较。如果这一新想法与各种各样的数据一致，那么地质界可能会有一个强大而可行的解决方案来解决科罗拉多高原隆起的长期问题。该项目正在为一名研究生提供建立地球定量模型的重要培训，并正在扩大未被充分代表的群体在地球科学领域的参与。在这项研究中开发的计算机模型和程序将适用于更广泛的地质界。

This project integrates available data on the tectonic and physiographic evolution of the Colorado Plateau to test a geodynamic model for the Tertiary history of this region. The centerpiece of this model is the idea that the Colorado Plateau is underlain by compositionally distinct mantle lithosphere that is depleted in basaltic components. In this scenario, intrinsic chemical buoyancy of the lithosphere may explain the enigmatic tectonic coherence and stability of the Colorado Plateau. The geodynamic implications of this idea are being explored by comparing numerical model results constraints derived from many diverse datasets, including: Tertiary magmatic patterns, heat flow, seismic velocity variations, xenoliths, rock exhumation, and rock and surface uplift. This research includes explicit consideration of possibly differing tectonic histories of the edges vs. the middle of the Colorado Plateau. The primary goal of this project is to shed light on two of the most puzzling aspects of the Tertiary evolution of the Colorado Plateau - the timing and mechanism of its rock and surface uplift and its relative tectonic stability during a time when vigorous magmatism and active deformation affected the rest of the western United States. The mechanism and timing of the uplift of the Colorado Plateau is a long-standing puzzle that has challenged some of the best geologists, including J.W. Powell, C. Dutton, and G.K. Gilbert. This project develops a new idea for the history of the region, namely that the uplift of the Colorado Plateau is intimately related to the chemical structure of the North American plate and is governed by intense heating and igneous activity that affected the plate since removal of the subducted Farallon plate beneath it. This idea will be tested using physics-based models and comparing results with observations from a range of disciplines. If this new idea is consistent with a wide variety of data, then the geologic community may have a robust and viable solution to the long-standing problem of the uplift of the Colorado Plateau. The project is providing important training for a graduate student in building quantitative models of the Earth and is broadening participation of underrepresented groups in the earth sciences. The computer models and programs developed in this research will be available to the wider geologic community.