The main aim of this project is to constrain the spatio-temporal paleo fluid circulation within the Agardhfjellet Fm., along part of the Billefjorden fault zone, and associated to the early Cretaceous magmatic intrusions of the Diabasodden suit, assessing the long-term permeability behavior of the Longyearbyen CO2 Lab. In particular, we aim at discriminate if the geological setting at the CO2 storage site allowed the circulation of fluids external to the local formation water. The project involves four steps: (1) Core review of calcite veins within deep boreholes and their sampling. Calcite veins are fossil traces of fluid circulation in the crust; (2) Field work at Vindodden site to study the Agardhfjellet Fm., the Billefjorden fault zone, and the Diabasodden intrusions. Field work and sampling will focus on calcite veins associated to the selected geological features; (3) carbon and oxygen stable and clumped isotope and U-Pb geochronological analyses of calcite veins to characterize the parent fluids from which calcite precipitated and the timing of Billefjorden fault and Diabasodden suit activities; (4) data comparison between veins from the cores and from the field.