As an innovation in the EU-funded H-2020 GREENPEG project (GA 869274), the Geological Survey of Norway (NGU) has developed a state-of-the-art piezoelectric seismograph (PE) as a valuable contribution to pegmatite exploration. The instrument utilizes the piezoelectric effect which describes the conversion of mechanical pressure, such as vibration or strain, into electrical energy, or vice versa. This technology has been leveraged to detect quartz, in particular for gold exploration, since the 1970s. NGU applied newest electrotechnology and data acquisition and processing to customize it for granitic pegmatite exploration. The pilot was deployed in different settings e.g. at the GREENPEG demonstration sites in Tysfjord, Norway, and could successfully detect buried quartz deposits, confirmed by drill cores. In the Tysfjord/Drag pegmatite field, the quartz core of the NYF pegmatite (Niobium-Yttrium-Fluorine) was detected at a depth of 5–10 m and underneath a 1-2 m thick quaternary overburden using minimal invasive explosive charges of ca. 100g. At a second site in Tysfjord/Håkonhals the quartz was found at even 15–25 m depth embedded in the host rocks amphibolite and gneisses, while using an 80 kg drop-weight with minimal environmental impact.
Figure 1. The NGU developed piezoelectric seismograph was deployed at the GREENPEG Tysfjord demonstration site in Håkonhals and Drag. A) shows a sketch of the developed system and B) the recorded and pre-processed signal produced from C) an 80kg drop-weight as seismic source
Since this novel piezoelectric seismograph is exclusively sensitive to the presence of quartz, it has a much lower ambiguity compared to other geophysical methods applied in pegmatite exploration and is a sustainable and cost-efficient method for this type of exploration, both as a stand-alone method or in combination with other methods on brownfields and greenfields.