Fluid Flow and Growth of Active Salt Structures at Decadal Timescales: Paradox Basin, Utah

该项目旨在量化蒸发岩（盐）矿床中的流体流动如何控制上地壳的三维脆性应变，以及溶质转移及其在地表和地下之间的联系。这项研究将有助于了解瞬态流体通量是如何在几天到几十年的时间尺度上、在几十米到公里的距离上驱动短期脆性应变的。研究小组将通过1:5 000比例尺的现场测绘和截面构建，InSAR场景分析，以及在快速滑动的边界断层上安装三分量延伸计（蠕变计）来表征地表活动变形。此外，研究人员将评估流经或直接流入地下盐的地表水和地下水的模式和速率，以及它对岩石强度的影响，这是由水力削弱和溶解控制的。将进行三维力学建模，以测试受地表观测应变、流体通量、地下水模拟、构造地质和地形限制的模型。目标是充分表征淡水如何在盐系统中移动，它如何通过溶解和盐岩强度的变化来调节塑性应变，以及地形在地表和地下耦合过程中所起的作用。工作?更广泛的意义包括理解盐体系中的流体流动和应变如何在其他方法无法获得的尺度上演化。研究人员特别感兴趣的是确定塑料盐流的短暂激增如何响应季节性地表径流和地下水补给的输入。现场工作位于犹他州东部的Paradox蒸发岩盆地，该地区以其非常暴露的岩石和丰富的地表和地下数据而闻名。这项工作将建立在最近在伊朗西部和以色列死海的无约束盐体中发现的瞬态涌动的基础上。这些构造由涌现的圆顶和纯岩盐流组成，是类似冰川的地质构造的现代例子，与含有大量石油储量的墨西哥湾等地区的特征相似。这项研究将确定控制盐结构变形和生长的条件，并将其与其中淡水流入和盐水流出等条件联系起来。这些研究将利用以往研究中无法获得的大量技术和数据。因此，最终目标是确定控制和指导其发展的物理条件，以便将其普遍应用于世界各地的其他盐结构。在全球范围内，这项工作对盐类盆地油气资源勘探具有重要意义。例如，2010年在墨西哥湾造成石油泄漏的“深水地平线”（Deepwater Horizon）油井是在一个盐结构中钻探的，而井喷的原因是流体压力的意外增加。此外，这项工作有望量化流入科罗拉多河和浅层地下水的盐水及其对美国西南部最大淡水来源水质退化的影响。

This project is aimed at quantifying how fluid flow in evaporite (salt) deposits controls 3D brittle strain in the upper crust, in addition to solute transfer and it's connections between Earth's surface and subsurface. The research will help understand how transient fluid flux drives short-term brittle strain at timescales of days to decades and distances of tens of meters to kilometers. The research team will characterize active surface deformation with 1:5,000 scale field mapping and construction of cross sections, analysis of InSAR scenes, and installation of a three-component extensometer (creep meter) across a rapidly slipping boundary fault. In addition researchers will assess patterns and rates of surface and groundwater flowing through or directly into buried salt and its effect on rock strength as governs by hydraulic weakening and dissolution. Three-dimensional mechanical modeling will be undertaken to test models constrained by observed strain at the surface, fluid flux, groundwater modeling, structural geology and topography. The goal is to fully characterize how fresh water moves through the salt system, how that modulates plastic strain by dissolution and changes on the strength of halite and the role topography plays in coupled surface and subsurface processes. The work?s broader significance includes understanding how fluid flow and strain in salt systems evolves at scales not available by other means. The researchers are particularly interested in determining how transient surges in plastic salt flow might respond to input of the seasonal influx of surface runoff and groundwater recharge. The field work is located in the Paradox evaporite basin in eastern Utah, a region noted for its extraordinarily well-exposed rocks and wealth of available surface and subsurface data.This work will build on the recent discovery of transient surges in unconfined salt bodies in western Iran and the Dead Sea in Israel. These structures, which consist of emergent domes and flows of pure rock salt are modern examples of geologic structures analogous to glaciers and are similar to features in areas such as the Gulf of Mexico that contain great petroleum reserves. The research will define the conditions that control deformation and growth of salt structures and relate this to conditions such as the inflow of fresh water and outflow of saline brines within them. These studies will utilize a wide array of techniques and data previously unavailable in past studies. The ultimate goal is thus to define the physical conditions that control and guide their development in order that this may be applied in general to other salt structures around the world. On a global scale, this work is of interest to responsible resource exploration in salt basins for hydrocarbons. For instance the Deepwater Horizon well that created the oil spill in the Gulf of Mexico in 2010 was being drilled into a salt structure, and the cause of the blowout was an unforeseen increase in fluid pressure. In addition, this work holds the promise to quantify the saline brine influx into the Colorado River and shallow groundwater and its effect on the degradation of water quality in the largest source of fresh water in the southwestern United States.