Holocene environmental changes from Dicksonfjorden sediments of western Spitsbergen, Arctic Svalbard

Abstract

Since the last deglaciation of the Svalbard-Barents ice sheet, which initiated ~13000 yrs BP, and the subsequent climate changes through the Holocene, the Svalbard fjords have faced dramatic environmental changes. Significant variations are thus expected in the mechanisms that determine the natureof sediments delivered to the fjords, including source rock erosion, chemical weathering, primary production in surface waters and terrestrial realm, and the main domain of sediment transport (i.e. ice-rafting vs. glaciofluvial). This study investigates paleoenvironmental changes in the western Svalbard region using the Holocene glaciomarine sediments deposited in the Dicksonfjorden of the west Spitsbergen, where the detrital sediment was likely derived from the Upper Paleozoic-Mesozoic mixed siliciclatic-carbonate sedimentary sequences distributed in the Dicksonland, covering the majority of the drainage basin. We examine geochemical composition of organic (carbon and nitrogen stable isotopes) and inorganic (major and trace elements concentrations) components of sediment, in order to investigate how sediment composition has changed in response to the climate changes. The result of analyses reveal that since the post-glacial sedimentation commenced in ~11,000 cal. yrs BP, geochemical composition of the Dicksonfjorden sediment records the climate variations throughout the Holocene, illustrating marked compositional changes that correspond to the major climate purturbations, such as the Holocene Climate Optimum and the 8,200 cal. yr BP cooling event. Moreover, the inorganic geochemistry of detrital sediment, especially Ca, Sr, and K levels, indicates consistent decrease and increase of carbonate and phyllosilicate minerals, respectively. We posit that sediment delivery from the carbonate-bearing Carboniferous-Permian strata exposed in the outer part of the fjord has progressively diminished, likely due to the retreat of the tidewater glaciers. Ultimately, this study aims to contribute to the mechanistic understanding of how the surface processes in the complex Arctic fjord system responded to the global climate changes.