Heterogeneity in geochemical expression of subaerial exposure in the Nashville Dome, Tennessee
Purdin, Bethany Jean
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1318 /C, /O, and wt % Sr data from 250 Middle Ordovician limestone samples from the Nashville Dome, Tennessee suggest that sampling along multiple vertical transects produces more representative isotopic and elemental characterization of a locality than single-sample strategies and will be more useful in future identification of surfaces of subaerial exposure. 10 vertical transects were sampled, each consisting of samples taken in 10 cm increments 1 m above and 2 m below the M4-M5 sequence boundary of Holland and Patzkowsky (1997, 1998). 13 Three exposure surfaces are identified. A significant increase in variance of /C, a 1318decrease in /C and wt % Sr, and a significant increase in /O below the proposed exposure surface characterize the M4-M5 sequence boundary. A peritidally-capped 13parasequence boundary at -120 cm is characterized by a significant decrease in /C, an 1813increase in /O, and an increase in variance of /C in the transgressive lag above the boundary.