Thermal field in Monti Sabatini lithostratigraphic successions

The characterisation of the thermal field of ground and its basal heat flow is important for the design of systems which exchange thermal energy with the ground. The present study investigates heat conduction in the substrates through a Distributed Temperature Sensing system. Vertical and horizontal thermal gradients are analysed. Seasonal fluctuations have an impact on the first layers of soil, with the amplitude of the thermal solicitation that gradually decreases with depth, while the presence of basal heat flow suggests the presence of upwellings hydrothermal fluids from the backdrop surface. The temperature in the Sabatini volcanic lithostratigraphic successions is far from being constant and uniform even at depths where the influence of surface heat transfer is not relevant. Indeed, other parameters such as the thermos-physical properties of ground and the groundwater flow have greater impact on the heat exchange. The deep geothermal heat flow is non-constant, positive up to a depth of 55 meters, while upper layers show negative or null values, implying at those depths basal heat flow becomes less significant compared to other heat exchange phenomena. Towards 85 metres depth geothermal heat flow fluctuates between 75 and 100 mW/m2.