Description: A marine sediment record from the central Bering Sea, spanning the last 20 thousand years (ka), was studied to unravel the depositional history with regard to terrigenous sediment supply and biogenic sedimentation. Methodic approaches comprised the inference of accumulation rates of siliciclastic and biogenic components, grain-size analysis, and (clay) mineralogy, as well as paleoclimatic modelling. Changes in the depositional history provides insight into land-ocean linkages of paleoenvironmental changes. During the finale of the Last Glacial Maximum, the depositional environment was characterized by hemipelagic background sedimentation. A marked change in the terrigenous sediment provenance during the late Heinrich 1 Stadial (15.7–14.5 ka), indicated by increases in kaolinite and a high glaciofluvial influx of clay, gives evidence of the deglaciation of the Brooks Range in the hinterland of Alaska. This meltwater pulse also stimulated the postglacial onset of biological productivity. Glacial melt implies regional climate warming during a time of widespread cooling on the northern hemisphere. Our simulation experiment with a coupled climate model suggests atmospheric teleconnections to the North Atlantic, with impacts on the dynamics of the Aleutian Low system that gave rise to warmer winters and an early onset of spring during that time. The late deglacial period between 14.5 and 11.0 ka was characterized by enhanced fluvial runoff and biological productivity in the course of climate amelioration, sea-level rise, seasonal sea-ice retreat, and permafrost thaw in the hinterland. The latter processes temporarily stalled during the Younger Dryas stadial (12.9-11.7 ka) and commenced again during the Preboreal (earliest Holocene), after 11.7 ka. High river runoff might have fertilized the Bering Sea and contributed to enhanced upper ocean stratification. Since 11.0 ka, advanced transgression has shifted the coast line and fluvial influence of the Yukon River away from the study site. The opening of the Bering Strait strengthened contour currents along the continental slope, leaving behind winnowed sand-rich sediments through the early to mid-Holocene, with non-deposition occurring since about 6.0 ka.

Description: We investigated plankton samples collected during RV Polarstern cruise ANT-XXVI/2 (from 27th November 2009 to 27th January 2010) along a broad E-W transect in the Pacific sector of the SO during austral summer. One hundred and fifty samples from twenty-nine stations were collected from the upper 150 m of the water column. Coccospheres per liter were counted using a scanning electronmicroscope (SEM). The different extant coccolithophore taxa numbers and assemblage distribution in relation to the frontal dynamics of the SO provide valuable information for potential future paleoceanographic reconstructions.

Description: This database contains the data resulting from a study of Antarctic Ice Sheet history, over the last ~500 thousand years. Iceberg-rafted debris (IRD), considered as an indicator of the presence of a continental ice sheet in the source area, is counted and analyzed in relation to the other components of the studied size fraction. The study materials are derived from two cores raised from a deep-water marine site in the southeastern Atlantic Ocean: the piston core TN057-6-PC4 and the associated drill core from the Ocean Drilling Program (ODP) Leg 177 Site 1090 (177-1090). Because the top portion of the 177-1090 drill core was apparently disturbed by the drilling, the piston core TN057-6-PC4 has been used to represent the most recent part of the record. The site is located at ~43 deg S, 9 deg E, about 2/3 of the way from the Antarctic coast to South Africa. The location from which both cores were raised is on the southern slope of the Agulhas Ridge, on the northern edge of the Agulhas Basin, in the southeastern Atlantic Ocean. The initial cleaning and preparation of samples from these cores was carried out by Kathryn Venz and David Hodell (UF). The methods used here to examine the IRD are those described by Allen and Warnke (1991, doi:10.2973/odp.proc.sr.114.118.1991), Stanton (1997), and Murphy et al. (2002, doi:10.1016/S0031-0182(01)00495-3). The samples were first weighed, then separated by sieving into four size fractions: 〈150 microns, 150-250 microns, 250 microns to 2 mm, and 〉2 mm. The medium to coarse sand size fraction (250 microns to 2 mm) was utilized for our study. Within this, a split of about 1000 grains was obtained; the grains in this split were counted. Grains that were counted within categories that included: quartz, feldspar, mafic minerals, lithic fragments, volcanic lithics, volcanic ash, diatoms, planktic forams, benthic forams, radiolarians, and 'other'. The counts of quartz, feldspar, mafic minerals and lithic non-volcanic fragments were then summed as IRD. Following the suggestion of Murphy et al. (2002), the final step of this stage was a brief overview of the non-counted portion of the 250 micron to 2 mm size fraction, primarily to look for 'background rafting'. Background rafting refers to the presence of IRD in the non-counted portion (i.e., outside of the counted split) of the size fraction. For this study, a note was made of the presence or absence only of any IRD clasts in the non-counted portion.