COLLABORATIVE RESEARCH: Hydrogeologic Analysis of Oriented Carbonate Concretions, Sierra Ladrones Formation, New Mexico

合作研究：新墨西哥州 Sierra Ladrones 地层定向碳酸盐结核的水文地质分析

• 批准号: 9726416
• 负责人: Peter Mozley
• 金额: $ 4.15万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-02-01 至 2002-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9726416&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Hydrogeologic; Analysis; Oriented

9726416 Mozley The effect of geological heterogeneity on fluid flow is one of the most difficult issues when dealing with problems of contaminant transport. Spatial variations in permeability result in spatial variations in velocity which in turn result in dispersion. Significant theoretical advances have provided a quantitative framework for understanding the relationship between geologic heterogeneity and dispersion. However, many questions remain regarding the nature of geologic heterogeneity and how fluids flow through media exhibiting multiple scales of heterogeneity. Two types of field studies have traditionally been used to complement the theoretical models. Large-scale subsurface tracer experiments focus on the spatial variation in hydraulic conductivity and the resulting plume behavior. Outcrop studies have provided insight into the nature of geologic heterogeneity and its relation to stochastic models. However, these two approaches are somewhat isolated in that the large scale tracer experiments have studied the evolution of plumes but are limited in their ability to document geologic heterogeneity and velocity correlation structure. Conversely, outcrop studies provide high-resolution information on the geologic heterogeneity, but historically, have not quantified an explicit flow component. We have found evidence that elements of diagenetic fabrics preserve quantitative information about the paleogroundwater flow in the Sierra Ladrones Formation, New Mexico. The orientations of elongate carbonate concretions ranging in size from centimeters to 10s of meters are interpreted as indicators of paleogroundwater flow direction. The proposed research will obtain important additional data and employ state-of-the-art quantitative methods to further test the hypothesis that concretion orientations record local groundwater flow directions. We will test this hypothesis by 1) obtaining additional data on the hydrogeology and concretion orientations, 2) obtaining high-resolution images of concretion chemistry and growth history, and 3) conducting numerical experiments of flow and chemical reactions to test conceptual models of concretion growth. Our mapping will include both meter-scale studies of primary sedimentary structures, concretion orientations, and permeability as well as mapping concretion orientations and facies assemblages at the scale of 100s of meters. We will test alternative models of concretion origin by characterizing geochemical zonation (ICP-MS and Ion Microprobe) and presence of relict microbial populations (SEM). Numerical modeling of flow, transport, and reactions will provide the quantitative means of synthesizing our hydrogeologic, petrographic, and geochemcial results. The research under this collaborative arrangement between Davis (EAR 9725194) and Mozley (EAR 9726416) will focus on hydrogeologic mapping (concretion orientations and hydrogeologic properties) and characterizing concretion growth characteristics (petrography and geochemistry). The reactive transport modeling will be conducted in a cooperative arrangement with Dr. H. Rajaram under EAR-9734404. If these oriented concretions do record paleogroundwater flow directions, they may provide further insight into how fluids flow through porous media over large spatial scale exhibiting multiple scales of heterogeneity.

9726416莫斯利：地质非均质性对流体流动的影响是处理污染物传输问题时最困难的问题之一。渗透率的空间变化导致速度的空间变化，进而导致弥散。重大的理论进展为理解地质非均质性和分散性之间的关系提供了一个量化框架。然而，关于地质非均质性的性质以及流体如何在表现出多个非均质性尺度的介质中流动，仍然存在许多问题。传统上，有两种类型的实地研究被用于补充理论模型。大规模地下示踪剂实验主要关注水力传导性的空间变化和由此产生的羽流行为。露头研究提供了对地质非均质性的本质及其与随机模型的关系的洞察。然而，这两种方法在某种程度上是孤立的，因为大规模示踪实验研究了羽流的演化，但它们记录地质非均质性和速度关联结构的能力有限。相反，露头研究提供了关于地质非均质性的高分辨率信息，但从历史上看，并没有量化明确的流动成分。我们发现有证据表明，成岩组构的元素保存了关于新墨西哥州塞拉·拉德隆斯组古地下水流动的定量信息。细长碳酸盐结核的大小范围从厘米到10s米的方向被解释为古地下水流动方向的指示器。这项拟议的研究将获得重要的补充数据，并使用最先进的定量方法来进一步验证固结方向记录当地地下水流动方向的假设。我们将通过1)获得更多关于水文地质和固结方向的数据，2)获得固结化学和生长历史的高分辨率图像，以及3)进行流动和化学反应的数值实验来验证固结增长的概念模型，来验证这一假设。我们的绘图将包括对原始沉积构造、结核方向和渗透率的米级研究，以及在100米级别的结核方向和相组合的绘图。我们将通过表征地化分带(电感耦合等离子体质谱和离子探针)和残留微生物种群的存在(扫描电子显微镜)来测试不同的固结起源模式。流动、输送和反应的数值模拟将提供综合我们的水文地质、岩石学和地球化学结果的定量手段。戴维斯(EAR 9725194)和莫斯利(EAR 9726416)的这项合作安排下的研究将侧重于水文地质填图(结核方向和水文地质属性)和表征结核生长特征(岩石学和地球化学)。反应性传输模型将在EAR-9734404下与H.Rajaram博士合作进行。如果这些定向结核确实记录了古地表水的流动方向，它们可能会进一步洞察流体如何在表现出多个非均质性尺度的大空间尺度上通过多孔介质流动。