This study will utilize Nd isotopic compositional changes in Miocene Fe-Mn oxide coatings and fish teeth to determine Middle and Late Miocene deep ocean circulation changes potentially caused by tectonic changes in sill depth at the Central American seaway. The PI suggests that based on prior investigations Nd isotopes recorded in such sedimentary repositories are indicators of different paleo water masses (NADW, AABW, AAIW). This time interval is of interest due to the uplift of the Panama Isthmus and a series of carbonate dissolution events seen successively in various places. These carbonate crash intervals have been attributed to dominance of corrosive Pacific/Southern Component Waters and the intervening preservation intervals to non-corrosive North Atlantic Deep Water. The study will use Nd isotope ratios to trace North Atlantic vs Pacific/Southern Ocean contributions in a set of cores over this critical time interval.
