Hydrogeologic Constraint on the origin of deep subsurface microorganisms within a Triassic Basin

Abstract

The thermal history of the Taylorsville basin indicates that the thermophilic anaerobic bacteria extracted from Triassic strata at 2800 m below the land surface within the basin probably migrated to their current location. In order to ascertain the most probable scenario for microbial transport, a two‐dimensional transient fluid flow and heat transport model of the Taylorsville basin was developed using the finite element method. The numerical model was constrained by tectonic and thermal histories of the basin, coupled with the permeability and porosity data extracted from core samples. The model demonstrates that a topographically driven groundwater flow system, caused by the tectonic uplift and erosion during the Jurassic, can explain the observed differential cooling of the basin. The computed groundwater flow rates during this period were on the order of 1 to 100 mm/yr. Combined with the cooling history of the microbially sampled strata, such rates provided a possible mechanism for the introduction of ancient surface or subsurface microorganisms to the deep subsurface. This tectogenetic mechanism may explain the origins of deep subsurface microorganisms for other regions of the Earth.