CONCLUSIONS

1. The shallow, vertical pore-water gradients observed along the Bahamas Transect are thought to be influenced primarily by differences in sediment reactivity, possibly induced by changes in sedimentation rates and strong bottom currents active since the late Pliocene.
2. Pore-fluid profiles in the lower Pliocene-Miocene sequences are dominated by diffusion and do not show significant evidence of subsurface advective flow. Deeper interstitial waters are believed to be the in situ fluids that have evolved mainly through interactions with sediments.
3. The increase in Na⁺ and Cl^- content observed with depth is postulated to result from the expulsion of Na⁺ and Cl^- into pore waters during alteration of metastable aragonite and HMC to LMC and dolomite. It is also possible that some of the increase is caused by upward diffusion of salt from Early Jurassic evaporites.
4. Pore-fluid chemistry is dominated by the influences of carbonate recrystallization, much of which is thought to occur soon after deposition during open exchange with bottom water. Extensive later stage burial diagenesis of carbonate is limited to zones of sulfate-reduction reactions, where enhanced carbonate dissolution occurs.
5. Marginal sites are characterized by alternations between sulfate-reducing and non-sulfate-reducing zones, which are controlled by the availability of labile organic matter and sulfate. Sulfate availability in deeper sediments is controlled by sulfur cycling pathways and the presence or absence of dissolved Fe²⁺. Interfaces between sulfate-reducing and non-sulfate-reducing zones are sites of ongoing reaction and precipitation of minerals such as celestite and barite.