An AI approach to automated magnetic formation mapping beneath cover

Pratt, David A.; McKenzie, K. Blair; White, Anthony S.

doi:10.1080/22020586.2019.12073001

Cited by 4 publications

(3 citation statements)

References 8 publications

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“…As noted by Pratt et al . (2019) over 90% of a magnetic signal arises from sources within 200 m of the surface. Figure 8(b) extends this analysis to a cluster of skarns where the observed magnetic anomaly is for a cluster of 12 skarns all having the same magnetic properties.…”

Section: Resultsmentioning

confidence: 99%

“…In our model, we limited the depth extent to just 50 m. Increasing the depth extent of the source body would increase the amplitude of the observed magnetic signal but no more than possibly doubling its amplitude. As noted by Pratt et al (2019) over 90% of a mag-netic signal arises from sources within 200 m of the surface. Figure 8(b) extends this analysis to a cluster of skarns where the observed magnetic anomaly is for a cluster of 12 skarns all having the same magnetic properties.…”

Section: Synthetic Model Of Skarn Anomaliesmentioning

confidence: 93%

“…The amplitude and morphology of the associated anomalous signature are also impacted by geometrical and locational aspects of the contributing anomalous sources. A large source body located at depth needs to have a significant petrophysical contrast for it to produce an anomalous signal detectable at the surface or from the air in the case of airborne surveys (Pratt et al ., 2019). A source body located near the surface can be detected with a lower degree of petrophysical contrast.…”

Section: Introductionmentioning

confidence: 99%

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Locating skarns with magnetic survey data, Geyer, Erzgebirge: optimizing data acquisition procedures

Ugalde

Morris

Madriz

et al. 2022

Geophysical Prospecting

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Magnetic data can be acquired from a number of different platforms (e.g., ground, drone, helicopter) using a variety of sensors (e.g., caesium vapour‐type optically pumped magnetometers, fluxgate, superconducting quantum interference devices) with different flight line configurations. To detect a magnetic anomaly associated with a mineral commodity that is not exposed but is thought to be associated with the anomalous magnetic mineral content, it is necessary to optimize the survey parameters through a complete data integration process. Prior petrophysical measurements provide insight into the physical contrast that might be expected between adjacent lithologic units and between the ore zone and the encompassing lithology. Oriented rock samples provide access to magnetic remanence data through palaeomagnetic laboratory measurements. Knowing the typical morphology of the ore zone one can compute a forward model of the expected anomalous response and determine which combination of survey parameters provides the highest probability of detecting the commodity being sought. In this study, we analyse magnetic patterns associated with thin dipping skarn bodies from the Geyer mining district in Erzgebirge, Germany. Petrophysical measurements indicate that the skarns are more magnetic than the surrounding host rock. Partially oriented samples from a bore core record a Variscan age metamorphic remanence. Forward modelling indicates that clusters of skarn bodies are required to produce a reliably detectable magnetic signal. Ground, or low elevation drone surveys are needed to detect these anomalies with standard scalar‐type optically pumped magnetometer or fluxgate magnetic surveys. The enhanced spatial resolution and long‐wavelength rejection of a superconducting quantum interference device based full‐tensor magnetic gradiometer provide an improvement over optically pumped magnetometers for an aircraft‐based survey platform.

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Section: Resultsmentioning

confidence: 99%

Section: Synthetic Model Of Skarn Anomaliesmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Locating skarns with magnetic survey data, Geyer, Erzgebirge: optimizing data acquisition procedures

Ugalde

Morris

Madriz

et al. 2022

Geophysical Prospecting

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Large-scale rock property and depth models for exploration targeting beneath cover

Pratt¹

2021

First International Meeting for Applied Geoscience &Amp; Energy Expanded Abstracts

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Commercial operation of a SQUID-based airborne magnetic gradiometer

Rudd¹,

Chubak²,

Larnier³

et al. 2022

The Leading Edge

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Gradient measurement of the magnetic field vector, especially full-tensor magnetic gradiometers (FTMGs), provides various advantages over gradient components derived from measurements of the total magnetic intensity (TMI). These advantages include higher spatial resolution, directional information, and thus more detailed anomaly delineation and a significantly better-constrained solution space for magnetic inversion and interpretation. However, the airborne application of FTMG instruments requires exceptionally high sensor resolution and low levels of motion noise to maximize these advantages and to achieve high exploration depth. Superconducting quantum interference detectors (SQUIDs) are an effective option for FTMG sensors, now available commercially in the system discussed herein. This SQUID sensor system comprises intrinsic planar-type gradiometers that produce data with sufficiently low noise for use on an airborne platform. The evolution and advancement of the system and its predecessor over the past two decades has produced a robust commercial system that produces high-quality full-tensor data sets from a helicopter-towed-bird implementation. Because the SQUID sensors measure directionally sensitive data, the processing of the acquired data is significantly more challenging than for TMI sensors. Noise induced by the motion of the bird during flight, especially rotational noise, must be monitored and compensated. The introduction of a more robust and aerodynamic bird has significantly reduced the noise of the system. This noise reduction translates into greater sensitivity and accuracy and, thus, heightened confidence in the use of the survey data sets. While much of the early use of the system has been in diamondiferous kimberlite exploration, the system has successfully flown surveys in mineral exploration for a variety of targets, including gold, nickel, and iron ore. These data sets provide greater confidence in the geologic interpretation across the survey areas. Other applications for FTMG surveying include infrastructure mapping, unexploded ordnance detection, and compensation of electromagnetic data sets in marine environments.

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An AI approach to automated magnetic formation mapping beneath cover

Cited by 4 publications

References 8 publications

Locating skarns with magnetic survey data, Geyer, Erzgebirge: optimizing data acquisition procedures

Locating skarns with magnetic survey data, Geyer, Erzgebirge: optimizing data acquisition procedures

Large-scale rock property and depth models for exploration targeting beneath cover

Commercial operation of a SQUID-based airborne magnetic gradiometer

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