Typifying pore waters composition of bottom sediments from the northwest Arctic shelf of the Barents and Kara Seas

This article investigates pore waters in poorly studied regions of the northwestern Russian Arctic shelf sedimentary deposits. The research was conducted on modern seabed sediment samples with a maximum thickness of three meters, collected during field marine expeditions in the northern region of the Barents-Kara Sea shelf. Processes of pore water chemical composition formation, their origin and evolution, as well as interactions with enclosing sediments, gases, and organic matter are considered. Particular emphasis is placed on the distinctive characteristics of these processes under low-temperature conditions, accounting for the specific Quaternary developmental history of the region. Acquiring new insights about the “pore-water–sediment” system is crucial both for understanding general arctic sedimentation processes and for locating hydrocarbon reservoirs on the Russian Arctic shelves. Typification of component composition in pore waters was achieved by combining statistical and geochemical approaches. As a result, four distinct types of pore waters were identified: sedimentational, diagenetic, desalinated and transitional. It was found that most analyzed pore water samples belong to the sedimentational type, which had not experienced significant changes through early diagenesis and resembled seawater composition. Some samples exhibited diagenetic-type pore waters formed through sulfate reduction processes, indicating initial diagenetic transformations towards direct metamorphization of their composition. Stations with weaker manifestations of diagenetic processes were classified into the transitional type. Desalinated-type stations included dense, Low-moisture sediment sample where decreased mineralization of pore waters due to almost proportional reductions in concentrations of major components was observed. The clustering methodology applied here can be applied to other marine Arctic regions.