Electric resistivity and compactness of sediments in the vicinity of boreholes drilled in the years 2007-2008 in the area of Starunia palaeontological site (Carpathian region, Ukraine)

Geoelectric research aiming to assess heterogeneity of geological environment was carried out in the Starunia area, where the unique specimens of woolly rhinoceros were discovered at the beginning of the 20th century. The DC azimuthal pole-dipole resistivity soundings and penetrometer-based resistivity profiling with simultaneous penetration-velocity measurements were used to study variability of environment in the vicinity of geological boreholes. No evident correlation was found between lithology of drilled sediments and geophysical data. Nevertheless, remarkable horizontal and vertical variability of geophysical parameters were observed. The largest horizontal changes may reflect an existence of some sharp boundaries in study area. The measured physical properties of geological strata: electric resistivity and compactness (estimated from penetration velocity) change also with the depth but correlation with geological structure can be found in limited cases only. Registered variability may have originated from several reasons: complex geological arrangement of shallow layers, salty underground water and bitumen presence in voids and pores, influence of neotectonic activity, and/or from transformations of near surface environment caused by past mining activity.