Mapping thermal tufa deposits using GPR

Tufa (freshwater calcareous) deposits can provide excellent targets for GPR exploration due to low clay content and low salinity. Widespread tufa deposits occur at the surface and in the shallow subsurface of Heber Valley, an alluvium-filled basin located in the Rocky Mountains of northern Utah (USA). A set of 200-MHz GPR profiles provides an unprecedented view of the internal structure of a tufa mound and its immediately surrounding platform. Our results indicate that features such as unconformities, caverns, disruptions due to voids, and “seismic” stratigraphic on-lap patterns can be mapped at high resolution. These patterns may be used to constrain interpretations of the episodic growth of a tufa system over geologic time.