High-resolution Accumulation Rate Variations on the Bermuda Rise During Marine Isotope Stage 3

North Atlantic sediment accumulation rates are sensitive to climate change due to variable supply from glacial delivery, wind-borne dust, productivity, dissolution, and sediment redeposition. Excess Th-230 profiling allows us to build a high resolution record of regional accumulation rate variations, as the flux of Th-230 to the seafloor beneath a region is known and lateral sediment reworking does not alter the primary sediment/Th-230 flux ratios. The Bermuda Rise contains a high resolution record of climate change during marine isotope stage 3 revealed through changes in %CaCO3, alkenone undersaturation index, benthic foraminiferal Cd/Ca, and accumulation rate variations. The average sedimentation rate between interstadials IS5 and IS16 is33 cm/kyr. We have made 350 excess Th-230 determinations for this interval giving an accumulation rate resolution averaging one century per sample. Combined with %CaCO3 data, this data allows for the calculation of regional carbonate and non-carbonate detritus accumulation rates. In this interval, noncarbonate accumulation rates vary by a factor of three, and carbonate accumulation rates vary by a factor of four. The highest non-carbonate peaks occur just before %CaCO3 peaks associated with interstadial IS8 (H4?) and IS12 (H5?) and perhaps surprisingly, also in the middle of the %CaCO3 peak associated with interstadial IS10, and in a doublet near the end of the %CaCO3 peak associated with interstadial IS6 and just before interstadial IS5. Smaller but significant noncarbonate accumulation peaks occur just before the carbonate peaks associated with IS16 and IS14, and at other times throughout MIS 3. After making some simple assumptions about sediment focusing, it is possible to use this accumulation rate information to construct linearized time scales that are independent of correlations with other climate records. Proxy indicators such as %CaCO3, Cd/Ca, and alkenone temperatures estimates will be compared to other climate records using these independent linearized time scales.