Geologic characteristics of permeable groundwater intervals defined by electromagnetic borehole flowmeter surveys on the Oak Ridge Reservation
- Oak Ridge National Lab., TN (United States)
The groundwater system in the Oak Ridge Reservation (ORR) area is stratigraphically controlled and divisible into aquitards, where flow is through fractures only, and aquifers, where flow is in karst conduits. An electromagnetic borehole flowmeter was used to survey 60 piezometer wells and 12 coreholes on the ORR. Piezometer well depths ranges from 5--80 ft with screen lengths of approximately 10 ft at various depths, and open corehole surveys reached depths of 350 ft. Previously, the results were used to develop a model for groundwater flow paths by assuming that permeable intervals consist of a single fracture intersecting the borehole. The purpose was to test this assumption by direct examination of core within permeable intervals. In addition, the geologic characteristics of the permeable intervals in non-cored piezometer wells have been interpreted based on correlations with nearby coreholes and geophysical logs. Occasionally, pinpointing the exact feature responsible for flow within a permeable interval was hampered by a relatively large sampling interval (>1 ft) of the flowmeter surveys. Regardless, potential transmissive features were identified by the presence of iron staining, euhedral calcite and gypsum crystallization, partial infilling of fractures, and dissolution features. Within carbonate units permeable intervals are associated with a number of different features: (1) open fractures normal and oblique to bedding that are parallel, oblique, and perpendicular to bedrock strike; (2) [<=]2 cm vugs that form within fracture mineral fillings; (3) [>=]3 cm solution cavities that are not fracture related; (4) open bed-parallel clay seams; and (5) open bed-parallel shear fractures. Within non-carbonate units permeable intervals consist of highly fractured zones, associated with changes in bedding dip and the development of shear fractures that are related to the development of faults and folds.
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6111073
- Report Number(s):
- CONF-9304188-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:4; Conference: 42. annual Geological Society of America (GSA) Southeastern Section meeting, Tallahassee, FL (United States), 1-2 Apr 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
AQUIFERS
GEOLOGY
HYDROLOGY
OAK RIDGE RESERVATION
ELECTROMAGNETIC SURVEYS
FLOW MODELS
GEOLOGIC FRACTURES
GROUND WATER
PERMEABILITY
STRATIGRAPHY
WATER WELLS
ELECTRICAL SURVEYS
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
HYDROGEN COMPOUNDS
MATHEMATICAL MODELS
NATIONAL ORGANIZATIONS
OXYGEN COMPOUNDS
SURVEYS
US DOE
US ERDA
US ORGANIZATIONS
WATER
WELLS
580000* - Geosciences
540250 - Environment
Terrestrial- Site Resource & Use Studies- (1990-)