Variations in Sea-Surface Temperature, Paleoproductivity and Circulation Pattern in the Eastern Equatorial Pacific During the Last 140 kyr: a Multiproxy Study of Core MD02- 2529

Eastern Equatorial Pacific is generally considered a key region for understanding of past climate dynamics in low latitudes, however, quantitative paleoceanographic data are limited by extensive dissolution of carbonate microfossils in the region. We estimated SST (at 10 m w.d.) and reconstructed changes in paleocirculation and paleoproductivity pattern by analyzing planktic foraminiferal and coccolithophore assemblages in IMAGES Core MD02-2529 (08°12.5' N, 84° 07.5' W, w.d. 1619 m). The stratigraphic framework based on d 18O record performed on C. wuellerstrorfi recovered the last 140 kyr. The magnitude of summer SST change estimated by MAT and ANN is similar, whereas MAT-derived winter SST are 0.5 to 2 °C higher than those obtained by ANN due to the differences between both methods and calibration datasets. ANN SSTs indicate a more gradual warming during the terminations and persistent mean-annual values of 25.5-26.5 °C during MIS 5.5, 5.1 and 1. MAT-derived maximum values reach 28.5 °C during MIS 5.5, i.e. corresponding to the present hydrological conditions, which most probably arise from the very scarce occurrence of cold-water N. pachyderma dex. during this interval as compared to a 1-5 % abundance of the species during MIS 1. LGM is not characterized by very low SST but rather by a cold subsurface to intermediate water advection, as follows from the permanent occurrence of the transitional deep-dwelling species G. inflata. The lowest SST values are estimated by both ANN and MAT methods for late MIS 3. Increased abundance of cold-water species G. bulloides and N. pachyderma dex., and low amount of tropical mixed-layer species during this time may point to stronger mixing likely due to an extension of the Costa Rica Dome. High percentages of tropical oligotrophic species are typical for interglacials thus pointing to relatively stable stratification and low wind stress in the shadow of two mountain chains. Variations in coccolithophore assemblages also follow long-term changes in mean-annual SST pattern as indicated by the ratio between G. oceanica and E. huxleyi. Levels of decreased abundance of F. profunda, a low primary production marker, indicate an enhancement of primary production during terminations. Among foraminifers two species, G. glutinata and G. tenella, show a strong correlation with primary production as shown by the appearance of short-term spikes at the end of terminations. Both findings imply intensified surface layer mixing at glacial-interglacial transitions due to a reorganisation of wind field and thermohaline circulation.