ALBERT

Description: We present results of Th/U dating, stable isotope and trace element data from a speleothem from Puerto Rico. Th/U dating was performed using isotope dilution MC-ICPMS. Activity ratios were corrected for initial Th assuming an detrital weight ratio 232Th/238U = 0.154 ± 0.038 (corresponding to an activity ratio of the detritus in secular equilibrium of (230Th/232Th)detr = 19.79 ± 4.93), and secular equilibrium of the detritus. Ages are calculated using the decay constants by Cheng et al. (2000)). Uncertainties are given as 2σ- range, and do not include half-life uncertainties. Th/U dating shows that stalagmite PR-LA-1 covers the period from 15.4 to 46.2 ka with a growth interruption between 35.5 and 41.1 ka. Stable isotope samples were drilled with a spatial resolution of 1 mm and measured using an IRMS equipped with a Gasbench. Element/Calcium ratios of the speleothem were measured by laser ablation ICPMS and were reduced to the resolution of the stable isotope records.

Description: We present a new speleothem trace element and stable isotope record, which extends previous paleoclimate evidence from Cuban speleothems to the last 96 ka. Stable isotope samples were micromilled at a resolution of 0.10-0.33mm, and measured using an IRMS equipped with a Gasbench. Line scans of Element/Calcium ratios of the speleothem were measured by laser ablation ICPMS and were reduced to the resolution of the stable isotope records.

Description: We present a new speleothem trace element and stable isotope record, which extends previous paleoclimate evidence from Cuban speleothems to the last 96 ka. Stable isotope samples were micromilled at a resolution of 0.10-0.33mm, and measured using an IRMS equipped with a Gasbench. Line scans of Element/Calcium ratios of the speleothem were measured by laser ablation ICPMS and were reduced to the resolution of the stable isotope records.

Description: For trace element analyses, single specimens of C. wuellerstorfi have been analyzed using femtosecond laser ablation inductively coupled plasma mass spectrometry (fs-LA-ICP131 MS) at the Geochemistry Laboratory at the Max Planck Institute for Chemistry. Na, Mg, and Sr of 142 specimens of C. wuellerstorfi have been measured at high-resolution on (up to) each of the final five chambers to eliminate possible inaccuracies that are likely to be caused by varying sample size. The fs-LA-ICP-MS analyses were performed on 25-μm diameter spots on each chamber with a pulse repetition rate of 15 Hz at low fluence (0.1-0.3 J/cm2). Calibration was performed with the microanalytical synthetic reference material MACS‐3 for carbonate and NIST612 for silica. Average values of all chambers analyzed in the same specimen were used for further analyses. Since foraminifers from different regions show particular offsets in the Mg/Ca composition of their shell, depending on region specific temperature ranges of ambient seawater, region-specific formulas are used. We have applied the formula Mg/Ca=0.82e^0.19*BWT of Tisserand et al. (2013) from samples collected from similar geographic situations to avoid offsets. The formula has been applied to calculate temperature variability of each analyzed chamber. The average value obtained from chamber-to-chamber temperature variability of each specimen has been applied as average temperature data of the entire test.

Description: Baffin Bay is a semi-enclosed basin connecting the Arctic Ocean and the western North Atlantic, thus making out a significant pathway for heat exchange. Here we reconstruct the alternating advection of relatively warmer and saline Atlantic waters versus the incursion of colder Arctic water masses entering Baffin Bay through the multiple gateways in the Canadian Arctic Archipelago and the Nares Strait during the Holocene. We carried out benthic foraminiferal assemblage analyses, X-ray fluorescence scanning, and radiocarbon dating of a 738 cm long marine sediment core retrieved from eastern Baffin Bay near Upernavik, Greenland (Core AMD14-204C; 987m water depth). Results reveal that eastern Baffin Bay was subjected to several oceanographic changes during the last 9.2 kyrCE1. Waning deglacial conditions with enhanced meltwater influxes and an extensive sea-ice cover prevailed in eastern Baffin Bay from 9.2 to 7.9 ka. A transition towards bottom water amelioration is recorded at 7.9 ka by increased advection of Atlantic water masses, encompassing the Holocene Thermal Maximum. A cold period with growing sea-ice cover at 6.7 ka interrupts the overall warm subsurface water conditions, promoted by a weaker northward flow of Atlantic waters. The onset of the neoglaciation at ca. 2.9 ka is marked by an abrupt transition towards a benthic fauna dominated by agglutinated species, likely in part explained by a reduction of the influx of Atlantic Water, allowing an increased influx of the cold, corrosive Baffin Bay Deep Water originating from the Arctic Ocean to enter Baffin Bay through the Nares Strait. These cold subsurface water conditions persisted throughout the Late Holocene, only interrupted by short-lived warmings superimposed on this cooling trend.

Description: Along with the radiation measurements, ROV positions were obtained from acoustic LBL (Long BaseLine)-positioning and all parameters of vehicle depth, distance to the ice and attitude recorded. All times are given in UTC.

Description: Along with the radiation measurements, ROV positions were obtained from acoustic LBL (Long BaseLine)-positioning and all parameters of vehicle depth, distance to the ice and attitude recorded. All times are given in UTC.