Early Diagenesis in coarse-grained siliciclastics capped by evaporites in Svalbard and East Greenland: Implications for Reservoir Potential.

This study aims to compare the local variations of early diagenesis of coarse-grained conglomerates overlain by gypsum evaporites using petrographic analysis, to examine whether there is a pattern in the diagenetic processes in this type of stratigraphic setting. The objective is to collect conglomerate samples from two separate fan systems along the hanging wall of Odelfjellet fault within the Billefjorden Trough in Petuniabukta, Svalbard. Sampling will take place during the summer of 2025, with eight days of field work, collecting samples from three different sites (two days per site). Transportation to the field site will be by zodiacs from Longyearbyen to a location approximately 65 km north. Accommodation throughout the field work period will be in Nostoc Czech Arctic Research Station, a polar-bear-safe container structure on the west coast of Petuniabukta. Samples will be brough back to Longyearbyen, and shipped to Denmark and Greenland Geological Survey (GEUS) to be cut into smaller pieces to make thin sections from. Petrographic analysis will be conducted on the thin sections, including examination via polarized light microscopy (PLM) to identify primary features (original clasts, grain size, sorting) and diagenetic (cementation, recrystallization, compaction) features. Early cements are often overgrown by later diagenetic phases, so recognizing cement stratigraphy is crucial. Point counting will be used to quantify the proportions of minerals, matrix, and cement types, providing quantitative data on mineralogy and porosity. Petrographic studies on Svalbard's silisiclastics are rare, with only one previous project (RiS ID 4330) in corporation with Longyearbyen CO2 Lab pilot project, showing moderate porosity but low permeability. this emphasize the importance of understanding the diagenesis and its impact on pore structure and fluid flow.