Description: Three cores recovered off the northwest of Svalbard were studied with respect to glacial/interglacial changes of clay and bulk mineralogy, lithology and organic geochemistry. The cores cover the Late Quaternary Marine Isotope Stages (MIS) 6–1 (ca. 170,000 years) and are located in the vicinity of the Polar Front which separates the warm Atlantic water of the Westspitsbergen Current and the cold Polar Water of the Transpolar Drift. Globally driven changes in the paleoenvironment like the variable advection of warm Atlantic water into the Arctic Ocean can be distinguished from regional events by means of source mineral signatures and organic geochemistry data. In particular, a combination of high organic carbon and low carbonate contents, high C/N-ratios, a particular lithology and a distinct bulk and clay mineral assemblage can be related to Svalbard ice sheet developments between 23,000 and 19,500 14C years. This complex sediment pattern has been traced to the northwest of Spitsbergen as far north as 82°N. Additionally, the same signature has been recognized in detail in upper MIS 5 sediments. The striking similarity of the history of the Svalbard/Barents Sea Ice Sheet during the late and early/middle Weichselian is elaborated. Both sediment horizons are intercalated between biogenic calcite rich core sequences which contain the so-called “High Productivity Zones” or “Nordway Events” related to the increased advection of warm Atlantic water to the Arctic Ocean. This study provides further evidence that the meridional circulation pattern has been present during most of the Weichselian and that the ice cover was often reduced in the northeastern Fram Strait and above the Yermak Plateau. Our findings contradict the widely used reconstructions in modelling of the last glaciation cycle and reveal a much more dynamic system in the Fram Strait and southwestern Eurasian Basin of the Arctic Ocean.

Description: A total of five sediment cores from three sites, the Arctic Ocean, the Fram Strait and the Greenland Sea, yielded evidence for geomagnetic reversal excursions and associated strong lows in relative palaeointensity during oxygen isotope stages 2 and 3. A general similarity of the obtained relative palaeointensity curves to reference data can be observed. However, in the very detail, results from this high‐resolution study differ from published records in a way that the prominent Laschamp excursion is clearly characterized by a significant field recovery when reaching the steepest negative inclinations, whereas only the N–R and R–N transitions are associated with the lowest values. Two subsequent excursions also reach nearly reversed inclinations but without any field recovery at that state. A total of 41 accelerator mass spectrometry (AMS) 14C ages appeared to allow a better age determination of these three directional excursions and related relative palaeointensity variations. However, although the three sites yielded more or less consistent chronological as well as palaeomagnetic results a comparison to another site, PS2644 in the Iceland Sea, revealed significant divergences in the ages of the geomagnetic field excursions of up to 4 ka even on basis of uncalibrated AMS 14C ages. This shift to older 14C ages cannot be explained by a time‐transgressive character of the excursions, because the distance between the sites is small when compared with the size of and the distance to the geodynamo in the Earth's outer core. The most likely explanation is a difference of reservoir ages and/or mixing with old 14C‐depleted CO2 from glacier ice expelled from Greenland at site PS2644.

Description: Three boreholes drilled during the International Ocean Discovery Program (IODP) Expedition 396 have yielded unexpected findings of altered granitic rocks covered by basalt flows, interbedded sediments and glacial mud near the continent‐ocean transition of the mid‐Norwegian margin. U‐Pb and K‐Ar geochronological analyses were conducted on both protolithic and authigenically formed K‐bearing minerals to determine the age of granite crystallisation and subsequent alteration episodes. The granite's crystallisation age based on 104 zircons is 56.3 ± 0.2 Ma, and subsequent exhumation along with alteration/weathering events took place between 54.7 ± 1 and 37.1 ± 1 Ma. This intrusion represents the youngest granite discovered in Norway and intruded at an extremely shallow crustal level before a rapid rift‐to‐drift transition. The shallow emplacement of granitic rock and its fast exhumation before and during the onset of volcanism holds significant implications for the syn‐ and post‐breakup tectonic evolution of volcanic margins.

Description: High sedimentation rates in fjords provide excellent possibilities for high resolution sedimentary and geochemical records over the Holocene. As a baseline for an improved interpretation of geochemical data from fjord sediment cores, this study aims to investigate the inorganic/organic geochemistry of surface sediments and to identify geochemical proxies for terrestrial input and river discharge in the Trondheimsfjord, central Norway. Sixty evenly distributed surface sediment samples were analysed for their elemental composition, total organic carbon (Corg), nitrogen (Norg) and organic carbon stable isotopes (d13Corg), bulk mineral composition and grain size distribution. Our results indicate carbonate marine productivity to be the main CaCO3 source. Also, a strong decreasing gradient of marine-derived organic matter from the entrance towards the fjord inner part is consistent with modern primary production data. We show that the origin of the organic matter as well as the distribution of CaCO3 in Trondheimsfjord sediments can be used as a proxy for the variable inflow of Atlantic water and changes in river runoff. Furthermore, the comparison of grain size independent Al-based trace element ratios with geochemical analysis from terrigenous sediments and bedrocks provides evidence that the distribution of K/Al, Ni/Al and K/Ni in the fjord sediments reflect regional sources of K and Ni in the northern and southern drainage basin of the Trondheimsfjord. Applying these findings to temporally well-constrained sediment records will provide important insights into both the palaeoenvironmental changes of the hinterland and the palaeoceanographic modifications in the Norwegian Sea as response to rapid climate changes and associated feedback mechanisms.

Description: The development of various combinative methods for Arctic sea ice reconstruction using the sympagic highly-branched isoprenoid IP25 in conjunction with pelagic biomarkers has often facilitated more detailed descriptions of sea ice conditions than using IP25 alone. Here, we investigated the complementary application of the Phytoplankton-IP25 index (PIP25) and a recently proposed Classification Tree (CT) model for describing shifts in sea ice conditions to assess the consistency of both methods. Based on biomarker data from three downcore records from the Barents Sea spanning millennial timescales, we showcase apparent and potential limitations of both approaches, and provide recommendations for their identification or prevention. Both methods provided generally consistent outcomes and, within the studied cores, captured abrupt shifts in sea ice regimes, such as those evident during the Younger Dryas, as well as more gradual trends in sea ice conditions during the Holocene. The most significant discrepancies occurred during periods of highly unstable climate change, such as those characteristic of the Younger Dryas-Holocene transition. Such intervals of increased discrepancy were identifiable by significant changes of HBI distributions and correlations to values not observed in proximal surface sediments. We suggest that periods of highly-fluctuating climate that are not represented in modern settings may hinder the performance and complementary application of PIP25 and CT-based methods, and that data visualisation techniques should be employed to identify such occurrences in downcore records. Additionally, due to the reliance of both methods on biomarker distributions, we emphasise the importance of accurate and consistent biomarker quantification for future investigations.