SEDIMENTARY RESPONSE TO OCEAN GATEWAY CIRCULATION CHANGES

Previous modeling studies suggested that changes in ocean gateways may have exerted a dramatic influence on the ocean circulation. In this p ilot study we extend those results to examining the potential ramifica tions of circulation changes on the sedimentary record. A version of t he Hamburg carbon cycle/sediment model is used in these sensitivity ex periments. Results indicate that internal reorganization of the ocean circulation can potentially cause very large regional changes in lysoc line depth (1500-3000 m) and opal deposition. These shifts are sometim es comparable in magnitude to those imposed by changes in external for cing (e.g., climate, sea level, and weathering). Comparisons of the mo del response with the geologic record indicate some significant levels of first-order agreement. This exercise suggests that opportunities n ow exist for physically based modeling of past sediment responses to c irculation and climate changes.