Sensitivity and response of beryllium-10 in marine sediments to rapid production changes (geomagnetic events): A box model study

Abstract

The response and the sensitivity of the marine beryllium-10 flux to abrupt production changes (e.g., caused by a geomagnetic event) are investigated by using a simple box model. The effect of mixing processes in the water column on the 10Be flux is simulated, and the influence of bioturbation on the sedimentary record is studied. While the effect of the oceanic residence time is found to be small, bioturbation can drastically change the shape and the amplitude of the modeled 10Be peak. The simulations indicate that 10Be production peaks persisting for more than 1500 years are recorded well in deep-sea sediments if bioturbation-induced integration times are small (tbio ≤ 1000 years), while sediment cores with t bio ≥ 1000 years are found to be not well suited for stratigraphic purposes. The results further show that the sedimentary 10Be peak lags initial signal. This time lag is almost independent of the event duration (for tbio ≤ 1000 years), ranging between about 400 and 600 years. Therefore the model results support the idea that marine 10Be peaks corresponding to geomagnetic events can be used as a global time marker to match marine, terrestrial, and ice core chronologies on the millennial and (if the time lag of (500 ± 100) years is considered) the submillennial timescale. Copyright 2007 by the American Geophysical Union.