High-resolution gamma ray attenuation density measurements on mining exploration drill cores, including cut cores

Abstract

Physical property measurements are increasingly important in mining exploration. For density determinations on rocks, one method applicable on exploration drill cores relies on gamma ray attenuation. This nondestructive method is ideal because each measurement takes only ten seconds, making it suitable for highresolution logging. However calibration has been problematic. In this paper we present new empirical, sitespecific correction equations for whole NQ and BQ cores. The corrections force back the gamma densities to the "true" values established by the immersion method. For the NQ core caliber, the density range extends to high values (massive pyrite, ~5 g/cm 3) and the correction is thought to be very robust. We also present additional empirical correction factors for cut cores which take into account the missing material. These "cut core correction factors", which are not site-specific, were established by making gamma density measurements on truncated aluminum cylinders of various residual thicknesses. Finally we show two examples of application for the Abitibi Greenstone Belt in Canada. The gamma ray attenuation measurement system is part of a multi-sensor core logger which also determines magnetic susceptibility, geochemistry and mineralogy on rock cores, and performs line-scan imaging. Highlights Physical property measurements are increasingly important in mining exploration Density can be measured on exploration drill cores using gamma ray attenuation New correction methods are presented to eliminate systematic errors Examples from the Abitibi Greenstone Belt are shown

Geothermal Resources Recognition and Characterization on the Basis of Well Logging and Petrophysical Laboratory Data, Polish Case Studies

“…Another example is uranium mining, where gammaray spectroscopy measurements are the input for the orogeny condition simulations [49]. Additionally, non-destructive laboratory and borehole measurements based on gamma radiation of rocks are popular for obtaining indispensable information on bulk density in mining exploitation [50]. The interest in radiogenic heat calculations based on spectral gamma-ray measurements, also using aero-geophysical acquisition, is also observed in Africa to determine the spatial distribution of radiogenic heat and temperature within the lithosphere, thanks to the relative ease of obtainment and cheap data [51,52].…”

Using machine learning to estimate a key missing geochemical variable in mining exploration: Application of the Random Forest algorithm to multi-sensor core logging data

“…4 to 7) and profiles for the eight other holes are available in Ross et al (2016b) and Schnitzler (2017). For further methodological details, the reader is referred to Ross et al (2013Ross et al ( , 2014aRoss et al ( , 2014b, Fresia (2013), Bourke and Ross (2016) and Ross and Bourke (2017).…”

“…the recent Integra Gold Rush competition). Even at the diamond drill core characterization stage, which used to consist primarily of a visual log by the geologist, more and more data is becoming available (e.g., physical rock properties, geochemistry, mineralogy, …) (e.g., Ross et al, 2013Ross et al, , 2016aJácomo et al, 2015;Ross and Bourke, 2017;Wang et al, 2017;Bérubé et al, 2018;Chen et al, 2018). Utilizing such large multiparameter datasets to their full potential requires specific algorithms such as multivariate statistical analysis (e.g., Fresia et al, 2017) or ensemble trees (e.g., Bérubé et al, 2018;Caté et al, 2018;Chen et al, 2018).…”