Delineating structures controlling sandstone-hosted base-metal deposits using high-resolution multicomponent seismic and radio-magnetotelluric methods: A case study from Northern Sweden

Abstract

Over the past few decades seismic methods have increasingly been used for the exploration of mineral, geothermal, and groundwater resources. Nevertheless, there have only been a few cases demonstrating the advantages of multicomponent seismic data for these purposes. To illustrate some of the benefits of three-component data, a test seismic survey, using 60 digital three-component sensors spaced between 2 m and 4 m and assembled in a 160 m-long prototype landstreamer, was carried out over shallow basement structures underlying mineralized horizons and over a magnetic lineament of unknown origin. Two different types of seismic sources, i.e., explosives and a sledgehammer, were used to survey an approximately 4 km-long seismic profile. Radio-magnetotelluric measurements were also carried out to provide constraints on the interpretation of the seismic data over a portion of the profile where explosive sources were used. Good quality seismic data were recorded on all three components, particularly when explosives were used as the seismic source. The vertical component data from the explosive sources image the top of the crystalline basement and its undulated/faulted surface at a depth of about 50 m-60 m. Supported by the radio-magnetotelluric results, however, shallower reflections are observed in the horizontal component data, one of them steeply dipping and associated with the magnetic lineament. The vertical component sledgehammer data also clearly image the crystalline basement and its undulations, but significant shear-wave signals are not present on the horizontal components. This study demonstrates that multicomponent seismic data can particularly be useful for providing information on shallow structures and in aiding mineral exploration where structural control on the mineralization is expected.