CHANGING ATMOSPHERIC DELTA-C-14 AND THE RECORD OF DEEP-WATER PALEOVENTILATION AGES

We propose a new calculation method to better estimate the deep water ventilation age from benthic-planktonic foraminifera C-14 ages. Our st udy is motivated by the fact that changes in atmospheric Delta(14)C th rough time can cause contemporary benthic and planktonic foraminifera to have different initial Delta(14) values. This effect can cause spur ious ventilation age changes to be interpreted from the geologic data. Using a new calculation method, C-14 projection ages, we recalculate the data from the Pacific Ocean. Contrary to previous results, we find that the Pacific intermediate and deep waters were about 600 years ol der than today at the last glacial maximum. In addition, there are pos sible signals of ventilation age change prior to ice sheet melting and at the Younger Dryas. However, the data are still too sparse to const rain these ventilation transients.