Heat transport by groundwater flow during the Baikal rift evolution

A two-dimensional modelling study of sedimentation, fluid flow, and heat flow in the Baikal rift basin undergoing flank uplift and basin subsidence has been performed in order to understand the impact of these processes on the surface heat flow signal. Heat flow anomalies of different scales and magnitudes have been observed at the sediment surface of the lake Baikal basin, and the presence of a hydrothermal vent suggests that fluids play an important role in the regional distribution of heat flow. The BASIN-code applied for this study allows to simulate topographically and compaction-driven hydrodynamical fluid flow and coupled heat transfer.The flank uplift history provides the basis for a regional groundwater circulation towards the central basin area, with predicted Darcy velocities at present-day situation in the basement varying between 1 and 100 cm/year. Within the basin, the presence of aquifers and the pinch-out layering has a major control on the flow field, and compaction-driven flow velocities are strongly altered when combined with topography-driven flow. When velocities in the basement are larger than several centimeters per year, the regional fluid circulation is an effective mechanism of heat redistribution. Heat is brought from the flanks towards the basin area, with largest heat transported at a depth of 1–2 km at both sides. During the flank uplift, heat advection increases, with secondary variation related to the deposition of sedimentary layers. The heat flow is increased over the basin and reduced in the flanks, with a total heat output balance always positive. The extra heat output over the modelled transection is 2–10% of the initial heat output. The maximum computed heat fluxes are smaller than measured in the heat flow anomalies of the lake Baikal basin. Nevertheless, the model suggests that flow in the sedimentary basin combined with a topographically driven heat advection in the surrounding basement is a sufficient mechanism to account for the increased heat flow over the basin and the main features of the heat flow distribution