Collaborative Research: Testing Hypotheses for Neotectonic Mantle-Driven Surface Uplift of the Colorado Plateau Region

该项目将研究大峡谷地区如何响应由上地幔对流驱动的地表隆起。这项研究的目标是利用大陆尺度的科罗拉多河系统作为一个充分暴露的野外实验室和一个敏感的测量仪器，来测量断层作用、火山作用、隆起、河流动力学和气候过程之间复杂的相互作用，这些过程共同塑造了这个经典地区的景观。使用的方法和方法包括各种测年技术（玄武岩流的Ar-Ar测年，钙华胶结物的u系列测年，砾石的宇宙成因年龄，年轻梯田的OSL测年），这些技术将用于确定梯田砾石的年龄。这些沉积物保存了过去的景观位置，因此可以用来测量隆起、切口速率和变化的景观。目的是通过确定切口率是否存在模拟地幔异常的空间模式，来验证地幔流动和浮力改变驱动科罗拉多高原地表隆起和长波地表变形的观点。这项研究将验证这样一种观点，即大峡谷和美国西部崎岖的地形正在被上地幔对流重新塑造。这种物质和流体的运动发生在地表以下数百公里处，包括由流动的岩石、部分熔体和流体组成的热浮力软流圈的上升流域，以及冷致密的北美岩石圈的下升流域。在过去的1000万年里，在科罗拉多高原地区，上升流似乎造成了400-1000米的地表隆起。这相当于该地区目前平均海拔的25-50%。这种抬升仍在继续。该研究计划包括将教学与研究相结合，并对众多研究生和本科生进行指导，其中包括来自美国西南部的西班牙裔和印第安人学生。该项目将改进科罗拉多高原隆起和峡谷雕刻的书面和网络材料，这些材料将通过国家公园管理局的网页和大峡谷国家公园新开放的时间之路地球科学教育展，与高原公园的地球科学解释联系起来。

This project will study how the Grand Canyon region is responding to surface uplift driven by upper mantle convection. The goal of the research is to use the continental-scale Colorado River system as a well exposed field laboratory and sensitive gauge of the complex interplay between the processes of faulting, volcanism, uplift, river dynamics, and climatic processes that, collectively, are shaping the landscape of this classic region. The methods and approaches to be used include a variety of dating techniques (Ar-Ar dating of basalt flows, U-series dating of travertine cements, cosmogenic ages of gravels, OSL dates on young terraces) that will be used to determine terrace gravel ages. These deposits preserve past landscape positions and hence can be used to gauge uplift, incision rates, and changing landscapes. The aim is to test the idea that mantle flow and buoyancy modification are driving surface uplift and long wavelength surface deformation of the Colorado Plateau by determining whether or not there are spatial patterns in incision rate that mimic mantle anomalies.This research will test the idea that the rugged topography of the Grand Canyon and western United States are being re-shaped today by upper mantle convection. This movement of mass and fluid is taking place hundreds of kilometers below the surface and involves upwelling domains of hot buoyant asthenosphere that consists of flowing rock, partial melt, and fluid, as well as downwelling domains of cold dense North American lithosphere. The upwellings appear to be responsible for 400-1000 meters of surface uplift that has taken place in the Colorado Plateau region in the last 10 million years. This amounts to 25-50% of the present average elevation of the region. This uplift is still ongoing. The research plan involves integration of teaching with research and mentorship of numerous graduate and undergraduate students, including Hispanic and Native American students from the southwestern U.S.. The project will lead to improved written and web materials on Colorado Plateau uplift and canyon carving that will be linked to geoscience interpretation for Plateau Parks via the National Park Service web pages and the newly opened Trail of Time Geoscience Education Exhibition at Grand Canyon National Park.