Oriented drill core provides a lot of detailed structural information about the geology of a project. Drillers mark the side of the drill core that either points down or up by using a special orientation device. Structural features, such as fractures, veins, and foliation, can be measured relative to the orientation line by measuring the so-called alpha and beta angles.
There are major issues with these measurements, which are a tedious and time-consuming task. The risk for erroneous and inconsequent measurements is large and it is very difficult to do a proper quality check or to verify how a measurement was taken.
The Minalyzer CS measures the drill core directly in the tray from a high resolution 3D point cloud model which makes the sub-sequent measuring accurate without any assumptions and without touching the core. Alpha and beta angles of planar structural features can be measured directly using a software module integrated in the Minalogger software. The structural feature is logged by clicking two points on the orientation line and three points on the feature to be logged. The method works for all sizes of drill core and even cut cores, such as half core, can be measured.
Measurement of a vein using the structural logging module integrated in the Minalogger software based on 3D point cloud model of a core tray.
Alpha and beta angles of planar structural features can now be measured quickly and accurately, saving time on time-consuming manual measurements, while also significantly reducing the risk of incorrect measurements. Measurements are stored digitally in direct relation to the drill core, eliminating the risks of erroneous recording of measurements. Adjustments can be made to the measurements if necessary, long after the cores have been sampled and sent to the archive without needing to physically retrieve the core trays. Senior geologists can easily perform a quality check of the measurements.
The alpha and beta angles are calculated through the purely mathematical relations between the planar structure, the orientation line, and the drill core itself. There is no need to do any calibrations, no zeroing of sensors, and no specification of drill core diameters. The method have been validated using pre-defined fractures with known alpha and beta angles over the complete angular range.
Planar Structural MeasurementsRead more