Peruvian coastal primary palaeo-productivity during the last 200 000 years

Abstract

Abstract Two times series of primary palaeo-productivity off the Peruvian coast over the last 200 000 years are presented for Ocean Drilling Leg 112 Sites: Site 681, Hole 681A at 11° and Site 686A, Hole 686A at 13° southern latitude. Estimates of primary palaeoproductivity are based on the transfer function PDU-3 that uses marine planktonic diatom assemblage distribution from surface sediment samples and a ten-year average primary productivity map over the area with a range of 37 to 365 gC/m 2 /year. Primary palaeoproductivity does not follow a simple glacial-interglacial mode; the record is more complex and above average palaeo-productivity occurred in Sites 681 and 686 over the following time intervals: 12 to 28, 60 to 68, and 148 to 160 ka; major increases in productivity were found during peak glaciations, and significant decreases occurred at 8, 24, 72 to 80, 112 to 128, and 160 to 168 ka. The averaged palaeo-productivity curve of 681A and 686A over the last 160 000 years is in inverse phase with the Vostok ice core atmospheric CO 2 indicating that part of the atmospheric CO 2 variations is linked to changes in the biological pump activities of the eastern Pacific boundary current system.