HR: 0800h
AN: H21E-1079    [Abstracts]
TI: Geochemical and Isotopic Constraints on Deep Ground Waters in the Bluegrass Region of Central Kentucky
AU: * Galvin, R S
EM: rsgalv1@uky.edu
AF: University of Kentucky, 101 Slone Research Bldg. , Lexington, KY 40506-0053 United States
AU: Rowe, H
EM: hrowe@uky.edu
AF: University of Kentucky, 101 Slone Research Bldg. , Lexington, KY 40506-0053 United States
AU: Brown, D T
EM: danbrown@uky.edu
AF: University of Kentucky, 101 Slone Research Bldg. , Lexington, KY 40506-0053 United States
AU: King, R L
EM: bking@engr.uky.edu
AF: University of Kentucky, 101 Slone Research Bldg. , Lexington, KY 40506-0053 United States
AB: The Cambro-Ordovician Knox Group Aquifer is a regionally extensive paleokarst ground water system that underlies much of the Interior Low Plateau and neighboring Central Lowland province of the United States. The geology and hydrology of the aquifer in the Bluegrass region of central Kentucky are regionally controlled by the north-trending Cincinnati Arch, and are locally controlled by the Jessamine Dome, the northeast-trending Kentucky River Fault and West Hickman Fault systems, and a system of northwest-trending fractures. Previous hydrological investigations elucidated two distinct zones of water within the aquifer as it occurs throughout the Bluegrass. A zone of low conductivity waters straddles the axis of the Cincinnati Arch north of the Kentucky River, which cuts across the axis of the Arch in the southern portion of the Bluegrass. Low conductivity waters are thought to be related to leakage of the Kentucky River into the top of the aquifer, and to vertical leakage that occurs along fracture and fault systems. High conductivity waters occur along the eastern and western flanks of the Arch. The purpose of the present investigation is to utilize the geochemical and isotopic characteristics of Knox Group Aquifer waters to assess local and regional flow dynamics (recharge/discharge/velocity) and hydrogeochemical evolution of waters in a structurally complex setting. Preliminary results from deep wells ($>$260 meters) indicate a dynamic range in chloride (10 to 412 ppm), sulfate (13 to 143 ppm), and fluoride (undetectable to 6 ppm), suggesting significant geochemical evolution of ground waters over short horizontal flow paths. Alkalinity concentrations range from 260 to 290 mg/L CaCO$_{3}$. Preliminary $\delta$$^{18}$O results from wells in the central and southwest Bluegrass are similar to the annual average $\delta$$^{18}$O of regional meteoric ($\sim$-7.0$\permil$).
DE: 1806 Chemistry of fresh water
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1040 Isotopic composition/chemistry
DE: 1045 Low-temperature geochemistry
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting