1 – direction and length of the profile in m 2 – sand with various water saturation levels 3 – basement or bedrock of gneissic rocks 4 – potential placer diamond traps as per GPR data
The main purpose of mapping the depth to bedrock was to identify “pockets”, which are potential trap sites for placer diamonds. The direction of GPR profile 1 was from exposed bedrock (gneiss) at surface towards the ocean over the beach sand deposits. Equipment: Loza-N GPR with 1 kV transmitter, length of transmitting and receiving antennae – 3 m (central frequency = 50 MHz). Measurement interval – 50 cm. As a result of GPR profiling, four potential placer diamond traps were identified, which were further confirmed by excavation. Diamonds were extracted from the traps localized on the GPR data. None of the prior EM methods applied in this area were so successful due to the high salinity of beach sands.