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

[506008]莫兹雷这是一个合作研究项目的提案，旨在研究冲积含水层中地下水流动与成岩作用之间的关系。地质学家很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，明确和定量地解释地下水流动的研究相对较少。地下水对成岩组构空间分布的控制作用更少受到关注。另一方面，水文地质学家开始建立描述水导率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的结果。将有关地质过程的信息纳入非均质性的定量模型需要了解这些过程与水力导电性空间分布之间的关系。在这项研究中，地下水流动与成岩作用之间的关系将研究上新世-更新世Sierra Ladrones组，这是新墨西哥州中部阿尔伯克基盆地的一个冲积含水层。前人的工作对研究区沉积和古地理环境有了全面的认识。本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——早期碳酸盐胶结作用的成因和空间分布的控制因素。第一个目标是戴维斯和他的同事们之前在研究地点的工作的自然延伸，研究沉积特征与异质性的关系。第二个目标建立在现场初步工作的基础上，表明胶结与过去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（新罕布什尔大学）负责，成岩/地球化学方面的研究将由P.S. Mozley（新墨西哥理工大学）负责。该研究将包括绘制现场胶结带的分布和方向，以及胶结物的岩石学和地球化学分析。本研究主要解决以下问题：(1)方解石胶结物的类型和空间分布是什么？(2)各类胶结物的来源是什么？(3)不同类型胶结层的渗透率特征是什么？(4)胶结物的空间分布和长形胶结物的取向是否可以用来推断饱和区过去的地下水流动状况？

9506008 Mozley 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 wil l 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?