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Origin and Migration of Appalachian Basin Brines by 87Sr/86Sr Analyses

Stephen Osborn
University of Arizona, Department of Hydrology and Water Resources Tucson, AZ
[email protected]

Strontium isotopes have been extensively employed as natural tracers of fluid flow and water rock interactions in sedimentary basins of varying lithologies. The strontium isotopic composition of Appalachian basin brines may provide insight into the geologic processes that control the accumulation and transport of petroleum and mineral resources in which they are often found in close association and may be used for targeted resource exploration in the region. The main objective of this project is to investigate the origin and migration of brines in the Appalachian basin by measurement of 87Sr/86Sr, in combination with elemental and stable isotopic (O, H) analyses.

Previous studies have been conducted on the geochemistry and geometry of ore deposits, fluid inclusions, and clay mineral assemblages in the Appalachian foreland basin providing compelling evidence that tectonically- and topographically- driven, basin scale, brine migration has occurred in the Appalachian foreland basin. Geochemical studies of Appalachian basin brines have been primarily focused on the Silurian section with little87Sr/86Sr analyses.

Brine samples were collected from the northern basin margin in the summer of 2007 from active oil and gas wells producing from discrete units of varying lithologies from the Upper Devonian Ohio Shale through the Ordovician Trenton Group. The87Sr/86Sr isotopic analyses will be conducted by thermal ionization mass spectrometry and combined with elemental chemistry and stable isotope composition to determine the fluid flow dynamics and the origin and composition of brines.

 

AAPG Search and Discovery Article #90070 © 2007 AAPG Foundation Grants in Aid