An extensive saline plume (> 250 km2) within the regionally important unconfined aquifer in the Neogene Ogallala Formation overlies the Panhandle oil and gas field in the Southern High Plains, Texas, USA. Relative to upgradient Ogallala water, the plume waters have δ18O (-6.7 to -8.8‰) and δD (-42 to -88‰) values that tend to be depleted and have higher Cl (> 150 mg/l) and SO4 (>75 mg/l) concentrations. Various end-member-mixing models suggest that the plume composition reflects the presence of paleowaters recharged during Middle to Late Wisconsinan time rather than salinization associated with petroleum production. Paleowaters probably mixed with salt-dissolution zone waters from the underlying Upper Permian formations before discharging upward into the Ogallala Formation. Cross-formational discharge is controlled primarily by the geometry of the underlying units, as influenced by the Amarillo uplift, pinch-out of the laterally adjoining confined aquifer in the Triassic Dockum Group, variations in the saturated thickness of the Ogallala aquifer and the presence of potential pathways related to salt dissolution. (C) 2000 Elsevier Science Ltd.
|Number of pages||16|
|State||Published - Jul 1 2000|
Bibliographical noteFunding Information:
Fryar, A.E., Mullican III, W.F., 1995. Delineating controls on the composition of ground water in the vicinity of the Pantex Plant, Southern High Plains, Texas. Univ. Texas at Austin, Bureau of Economic Geology, report prepared for the US Department of Energy under subgrant to grant no. DE-FG04-90AL65847.
Our research was supported by grants from the Geological Society of America, the American Association of Petroleum Geologists and the University of Kentucky. The Texas Water Development Board and the Panhandle Groundwater Conservation District #3 provided relevant data. We thank Jim Crutchfield, Gerald Thomas, Bill McClain, Eric Wallin, Larry Mack and the Kentucky Geological Survey for assistance with chemical and isotopic analyses. Alan Dutton, Donald Whittemore, Steve Fisher and Bill Thomas provided thoughtful reviews. We appreciate the cooperation of those landowners whose wells we sampled, especially Jack Curtis.
ASJC Scopus subject areas
- Environmental Chemistry
- Geochemistry and Petrology