CRETACEOUS-PALEOCENE CALCITE COMPENSATION DEPTH FLUCTUATIONS IN THE ATLANTIC AND PACIFIC OCEANS

The calcite compensation depth (CCD) is the controlling factor for the deposition of deep sea carbonates. Because it is dependent on factors such as water chemistry, sea level, climate, primary productivity, and tectonics, fluctuations in the CCD are indicative of regional-global oceanographic changes. The most comprehensive research on changes in the CCD was completed in the 1970s and 1980s. Since that time there have been major advances in age control, significant revisions of the geologic time scale, as well as the completion of several more ocean drilling legs, all of which increase the resolution at which the CCD can be reconstructed. To determine the response of the Cretaceous and Paleocene oceans to climatic, oceanic, and tectonic events we have constructed CCD curves for the Atlantic and Pacific Ocean basins. Results show at least two instances of marked shoaling in the Atlantic during the middle to late Cretaceous while the Pacific Ocean levels remained constant until major perturbations in the latest Cretaceous. Data confirm previous studies and provide added constraints on the timing and magnitude of shifts in the CCD and their relation to major changes in climate and oceanography.