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Collaborative Research: Quantifying crustal hydration effects in the Colorado Plateau from xenoliths

合作研究：通过捕虏体量化科罗拉多高原的地壳水合效应

基本信息

批准号：
1937343
负责人：
Kevin Mahan
金额：
$ 28.1万
依托单位：
University of Colorado at Boulder
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-01 至 2024-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1937343&HistoricalAwards=false
关键词：
Collaborative Research Quantifying crustal hydration

项目摘要

The Colorado Plateau in the western United States incorporates spectacular natural landscapes, such as Grand Canyon, Zion, and Arches National Parks. This region was at sea level 100 million years ago and now sits at an elevation of about 2 kilometers above sea level. However, the reasons why surface elevations in this region increased are not well understood. This project will investigate the viability of one of several proposed mechanisms that have generated considerable debate over the last several decades. Specifically, this research will address whether hydration of Earth’s crust by water derived from a subducted fragment of the Pacific oceanic plate reduced its density and caused the ground surface to rise. This is based on the same principles that govern how high blocks of wood with different densities will float in water. The results of this research could have far-reaching implications because causal mechanisms for high elevations in the broader Rocky Mountain region and High Plains (including Denver, the “Mile High City”) may be due to processes that also affect other mountainous regions such as the Andes. Common educational themes among all of the activities in this project include graduate and undergraduate education and training, international collaborations with researchers in France, and enhancement of underrepresented minority students in Earth science.This project will investigate the hypothesis that hydrous alteration changed the mineralogical makeup and associated density structure of the Colorado Plateau lower crust and contributed significantly to its 2 kilometers surface uplift via isostatic adjustment. This research will integrate new petrologic, geochronologic, and stable hydrogen isotopic studies of a suite of crustal xenoliths from the approximately 25-million-year-old Navajo Volcanic Field. A post-hydration (present-day) model of the central Colorado Plateau crust will be developed that incorporates new observations from xenoliths, and ensures compatibility with modern seismic and other geophysical data. This will be evaluated along with a pre-hydration model for the crust that is based on detailed xenolith analyses. Calculated differences in pre-and post-hydration model densities will be used to constrain the potential isostatic response to alteration.This project is jointly funded by the Tectonics program and the Petrology & Geochemistry program in the Division of Earth Sciences.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.

位于美国西部的科罗拉多高原拥有壮观的自然景观，如大峡谷、锡安和拱门国家公园。该地区在1亿年前处于海平面，现在位于海拔约2公里的高度。然而，这一地区地表海拔上升的原因尚不清楚。该项目将调查过去几十年来引起大量辩论的几个拟议机制之一的可行性。具体来说，这项研究将解决是否水的地壳水化来自太平洋板块俯冲的片段减少其密度，并导致地面上升。这是基于相同的原则，管理多高的木块与不同的密度将漂浮在水中。这项研究的结果可能具有深远的影响，因为在更广泛的落基山脉地区和高平原（包括丹佛，“英里高的城市”）的高海拔的因果机制可能是由于过程，也影响其他山区，如安第斯山脉。该项目所有活动的共同教育主题包括研究生和本科生教育和培训，与法国研究人员的国际合作，该项目将调查含水蚀变改变了科罗拉多高原下地壳的矿物组成和相关密度结构，并对其2公里的表面产生重大影响的假设通过均衡调整而抬升。这项研究将整合新的岩石学，地质年代学和稳定的氢同位素研究的一套地壳捕虏体从大约2500万年的纳瓦霍火山场。将开发一个科罗拉多高原中部地壳的水化后（现今）模型，该模型将纳入捕虏体的新观测结果，并确保与现代地震和其他地球物理数据的兼容性。这将与基于详细捕虏体分析的地壳水化前模型一起沿着进行评价。水化前后模型密度的计算差异将被用来限制潜在的均衡变化响应。该项目由地球科学部的构造学计划和岩石学地球化学计划共同资助。该奖项反映了NSF的法定使命，并被认为值得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来支持。