Chemical signature detection of groundwater and geothermal waters for evidence of crustal deformation along fault zones

Abstract

Common crustal igneous and high grade metamorphic rocks contain peroxy defects which remain dormant until the rock experiences stress upon deformation. Stress activated peroxy defects form highly reactive oxygen species (ROS) at the rock-water interface observed in both terrestrial and extraterrestrial rock samples. The ROS complex is formed upon rock fluid interaction when groundwater combines with the ROS to produce hydrogen peroxide giving an indirect measure of the underlying rock stress and crustal deformation along active faults. The average concentration of hydrogen peroxide from the Sohna thermal spring water falling along the active Sohna fault and geothermal field was measured to be ~ 0.53 ± 0.014 mg/l. Similar average concentration was also recorded from borewell sample north of the spring (~0.56 ± 0.017 mg/l) within the same geothermal field. Lower concentration of hydrogen peroxide was recorded within samples collected from hard rock aquifers outside the geothermal field and the active fault zone (~0.138 ± 0.095 mg/l). The detailed analysis suggests that the presence of hydrogen peroxide is largely dependent on the circulation pattern through the interconnected fractures/joints within the quartzite bedrock lying adjacent to the fault plane. Laboratory analysis results also show high hydrogen peroxide concentration within two borewell samples falling adjacent to the epicentre of a shallow microtremor event within the hard rock region falling alongside a lineament along the Delhi hard rock mega fold. Rock water interaction post stress activation of peroxy defects and formation of ROS has therefore been inferred to be responsible for the formation of hydrogen peroxide at the rock water interface within these zones. This pilot study provides scientific field evidence that hydrogen peroxide concentrations within groundwaters might offer prospects for seismic stress estimation and crustal deformation along seismically active zones.