Can Electromagnetic Surveys Image Deep Crystalline Basement Flow Systems in Extensional Terrains?

结晶基底岩是由结晶矿物组成的岩石。这些基岩形成于地球历史的早期，通常埋藏在较年轻的岩石和沉积物之下。这些岩石通常被认为是不透水的，几乎没有水流过它们。然而，结晶基岩中的断层或裂缝可以允许流体流动。这项研究使用最先进的仪器对新墨西哥州地下近10公里处的地下进行成像。这项研究考察了在构造活动区的基底岩石中是否以及何时发生了流体流动。这项调查的结果和理解有助于量化美国西部深层基底岩石中微咸水的年龄和数量。这项研究与水资源管理者和核废料管理机构有关。该项目包括对水文学和地球物理领域的研究生和本科生的培训，支持一名职业生涯早期的教员，并支持一家拉美裔服务机构的研究团队。该项目的主要目标是开发一个新的框架，通过集成流体流动和传输模型、大地电磁(MT)和时间域电磁(TDEM)地球物理调查、地球化学和同位素示踪剂、温度剖面数据和断裂孔洞露头尺度测量来探索伸展地形中的深层地下水流动系统。通常，水文地质学家认为结晶的基底岩石是不透水的。另一方面，地热勘探学家承认，基岩内的离散断裂带是可渗透的，但很少有人关注向断裂带输送的流体的来源。这项研究提供了一个引人注目的范例，在这个范例中，构造活动区的结晶基底可以具有相对较高的体积渗透率，充当水、溶质和能量的主要传输者。该项目以格兰德河裂谷为试验台，将地球物理(电磁)、化探和野外观测与先进的数值模型相结合，探索这些深层水文系统的流动和输送特征，达到前所未有的深度。这一努力所取得的成果和所获得的理解将有助于量化美国西部深层含水层中微咸水的数量、盐度、停留时间和成因--这是一种有潜力弥补干旱环境中水和能源不足的非常规资源。该项目利用了作为新墨西哥州EPSCoR项目的一部分获得的基础设施和设备。该奖项反映了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。

Crystalline basement rocks are rocks composed of crystalized minerals. These basement rocks formed early in the history of the Earth and are typically buried under younger rocks and sediment. These rocks are commonly viewed as impermeable with little or no water flowing through them. However, faults or cracks in crystalline basement rocks can permit fluid flow. This study uses state-of-the-art instruments to image the subsurface at depths to nearly 10 km below the ground surface in New Mexico. The study examines if and when fluid flow occurs in basement rocks in a tectonically active region. The outcomes and understanding gained with this investigation can help quantify the age and amount of brackish water that resides within deep basement rocks in the western USA. This research is relevant to water resource managers and nuclear waste management agencies. The project includes training for both graduate and undergraduate students in the fields of hydrology and geophysics, supports an early-career faculty member, and supports a research team at a Hispanic-serving institution.The primary goal of this project is to develop a novel framework to explore deep groundwater flow systems in extensional terrains by integrating fluid flow and transport models, magnetotelluric (MT) and time domain electromagnetic (TDEM) geophysical surveys, geochemical and isotopic tracers, temperature profile data, and outcrop-scale measurements of fracture apertures. Typically, hydrogeologists view the crystalline basement rocks as impermeable. On the other hand, geothermal explorationists acknowledge that discrete fault zones within the basement rocks can be permeable but little attention has been devoted to the source of the fluids feeding the fault zones. This study offers a compelling paradigm in which the crystalline basement in tectonically active regions can have a relatively high bulk permeability, serving as a major conveyor for water, solutes, and energy. Using the Rio Grande rift as a test bed, this project combines geophysical (electromagnetic), geochemical, and field observations with advanced numerical models to explore the flow and transport characteristics of these deep hydrologic systems to unprecedented depths. The outcomes and understanding gained with this effort will help quantify the volumes, salinity, residence times, and genesis of brackish water within deep aquifers in the western USA - an unconventional resource with the potential to offset the deficit of water and energy in arid environments. The project leverages infrastructure and equipment acquired as part of New Mexico EPSCoR Energize New Mexico.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.