Collaborative Research: Hydrologic Implications of Carbonate Cementation in an Alluvial Aquifer, Sierra Ladrones Formation, New Mexico

9506474戴维斯这项提议是为了一个合作研究项目，调查冲积含水层中地下水流动和成岩作用之间的关系。地质学家早就认识到地下水在沉积物的物理和化学变化中的重要性。然而，对地下水流动进行明确和定量解释的研究相对较少。地下水对成岩组构空间分布的控制作用甚至更少受到关注。另一方面，水文地质学家开始建立描述水力传导性空间分布的定量模型。从地质角度看，导水率的空间分布是沉积和成岩作用共同作用的结果。将有关地质过程的信息纳入非均质性的定量模型中，需要了解这些过程与水力传导性的空间分布之间的关系。在这项研究中，地下水流动和成岩作用之间的关系将在新墨西哥州中部阿尔伯克基盆地的冲积含水层--上更新世的塞拉-拉德隆斯地层中进行研究。以前的工作使人们对研究区的沉积和古地理背景有了全面的了解。这项研究有两个主要目的：(1)确定早期碳酸盐胶结作用对非均质性的影响；(2)了解影响单元渗透率的主要成岩蚀变--早期碳酸盐胶结的成因和空间分布的控制。第一个目标是戴维斯和他的同事在研究地点之前的工作的自然延伸，调查沉积特征与非均质性的关系。第二个目标建立在现场初步工作的基础上，表明胶结作用与过去的流体流动条件之间存在密切关系。水文方面的研究将由J.M.Davis(新汉普郡大学)负责，成岩/地球化学方面将由P.S.Mozley(新墨西哥理工学院)负责。这项研究将包括绘制油田胶结带的分布和方向图，以及胶结物的岩石学和地球化学分析。研究的主要问题是：(1)方解石胶结物的类型和空间分布是什么？(2)各种胶结物的来源是什么？(3)不同类型胶结物的渗透性特征是什么？(4)胶结物的空间分布和细长固结的方向能否用来推断饱和带过去的地下水流动条件？

9506474 Davis This proposal is for a collaborative research project investigating the relationships between groundwater flow and diagenesis in alluvial aquifers. Geologists have long recognized the importance of groundwater in the physical and chemical alteration of sediments. However, relatively few studies have been conducted that explicitly and quantitatively account for groundwater flow. Groundwater controls on the spatial distribution of diagenetic fabrics have received even less attention. Hydrogeologists, on the other hand, are beginning to formulate quantitative models describing the spatial distribution of hydraulic conductivity. From a geological perspective, the spatial distribution of hydraulic conductivity is a result of the processes of deposition and diagenesis. Incorporating information about geological processes into quantitative models of heterogeneity requires an understanding of the relationship between the processes and the spatial distribution of hydraulic conductivity. In this study, the relationship between groundwater flow and diagenesis will be investigated in the Plio-Pleistocene Sierra Ladrones Formation, an alluvial aquifer in the Albuquerque Basin of central New Mexico. Previous work has resulted in a comprehensive understanding of the depositional and paleogeographic setting of the study area. The proposed research has two principal objectives: (1) to determine the influence of early carbonate cementation on heterogeneity, and (2) to understand the controls on the origin and spatial distribution of early carbonate cement, the main diagenetic alteration influencing permeability in the unit. The first objective is a natural extension of previous work at the study site by Davis and colleagues, investigating the relationship of depositional features to heterogeneity. The second objective builds upon preliminary work at the site that indicates a close relationship between cementation and past fluid flow conditions. The hydrological aspects of the study will be the responsibility of J. M. Davis (University of New Hampshire) and the diagenetic/geochemical aspects will be the responsibility of P.S. Mozley (New Mexico Tech). The study will involved mapping the distribution and orientation of cemented zones in the field, and petrographic and geochemical analysis of the cements. The principal questions addressed by the proposed research are: (1) What are the types and spatial distributions of the calcite cements? (2) What is the origin of the various types of cements? (3) What are the permeability characteristics of the different types of cemented zones? (4) Can the spatial distribution of the cements and the orientation of elongate concretions be used to infer past groundwater flow conditions in the saturated zone?