Fluid migration in a cratonic setting: The fluid histories of two fault zones in the eastern midcontinent

A combined field, petrographic, fluid inclusion, and stable isotope study was undertaken in two fault zones in the eastern midcontinent of the North American craton in order to determine their fluid histories. Because both the Kentucky River fault zone in central Kentucky and the Bowling Green fault zone in northwest Ohio were active intermittently throughout much of the Paleozoic, it was thought that one or both may record the passage of the late Paleozoic brine migration that affected large portions of the eastern midcontinent. Three fluid events were recognized in calcite veins of the Kentucky River fault zone. Each tapped the same dominantly meteoric, low-salinity fluid reservoir, but at different times as the fault zone was cooling (T(h) 110??to 75??C) at relatively shallow depths (