Airborne vector magnetics mapping of remanently magnetized banded iron formations at Rocklea, Western Australia

Dransfield, Mark; Christensen, Asbjørn Nørlund

doi:10.1071/eg03093

Cited by 27 publications

(12 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, additional efforts are required near the magnetic equator. Alternatively, vector magnetic surveys are now becoming available ͑e.g., Dransfield et al, 2003͒, and the observed three-component data can be used directly in the estimation.…”

Section: Helbig's Moment Methodsmentioning

confidence: 99%

Comprehensive approaches to 3D inversion of magnetic data affected by remanent magnetization

et al. 2010

View full text Add to dashboard Cite

Three-dimensional ͑3D͒ inversion of magnetic data to recover a distribution of magnetic susceptibility has been successfully used for mineral exploration during the last decade. However, the unknown direction of magnetization has limited the use of this technique when significant remanence is present. We have developed a comprehensive methodology for solving this problem by examining two classes of approaches and have formulated a suite of methods of practical utility. The first class focuses on estimating total magnetization direction and then incorporating the resultant direction into an inversion algorithm that assumes a known direction. The second class focuses on direct inversion of the amplitude of the magnetic anomaly vector. Amplitude data depend weakly upon magnetization direction and are amenable to direct inversion for the magnitude of magnetization vector in 3D subsurface. Two sets of high-resolution aeromagnetic data acquired for diamond exploration in the Canadian Arctic are used to illustrate the methods'usefulness.

show abstract

Section: Helbig's Moment Methodsmentioning

confidence: 99%

Comprehensive approaches to 3D inversion of magnetic data affected by remanent magnetization

et al. 2010

View full text Add to dashboard Cite

show abstract

“…There are a few systems that can acquire threecomponent magnetic data (e.g., Dransfield et al, 2003). In such cases, the data can be used directly in amplitude data calculation as the preferred approach.…”

Section: Calculation Of Amplitude Datamentioning

confidence: 99%

Application of 3D magnetic amplitude inversion to iron oxide-copper-gold deposits at low magnetic latitudes: A case study from Carajás Mineral Province, Brazil

Leão‐Santos

Moraes

2015

GEOPHYSICS

View full text Add to dashboard Cite

Strong hydrothermal alteration modifies rock physical properties in iron oxide-copper-gold deposits (IOCGs) and may result in characteristic signatures detectable in geophysical surveys. Magnetic data are commonly used in characterizing orebodies, and 3D inversions are often used to assist in interpretations. In areas with strong remanence and self-demagnetization, the total magnetization can have directions different from the inducing field direction. This deviation precludes the use of traditional inversion methods. Magnetic amplitude inversion offers one solution to this challenge because the amplitude data are weakly dependent on the magnetization direction. In addition, the low magnetic latitude also imposes difficulty in amplitude data calculation due to the instability in the component conversion in the wavenumber domain. To formulate a practical approach, we present a case study on applying the magnetic amplitude inversion to the Furnas southeast IOCG deposit at the low magnetic latitude in Carajás Mineral Province, Brazil, and demonstrate that the approach can reliably recover an interpretable distribution of effective magnetic susceptibility and identify massive magnetite from hydrothermal alterations associated with the high-grade ore.

show abstract

“…This is an important characteristic compared with the TFA. Besides, the 2D TMA requires the computations of the two orthogonal components B x and B z , which usually are transformed from the TFA unless component measurements are available (Li and Li, 2014), such as in airborne vector magnetics mapping (Dransfield et al, 2003) and 3C borehole measurements (Liu et al, 2013). For example, Gerovska and Araúzo-Bravo (2006) compute the observed magnetic field to the north, east, and vertically down-direction field components in the Fourier domain on the basis of the general analytic expression of the complex Fourier spectrum of the magnetic field.…”

Section: Magnetization Intensity Inversion For Amplitude Datamentioning

confidence: 99%

2D sequential inversion of total magnitude and total magnetic anomaly data affected by remanent magnetization

Liu

et al. 2015

GEOPHYSICS

View full text Add to dashboard Cite

Remanent magnetization complicates the inversion of magnetic data due to altering the strength and direction of the magnetization vector. To deal with the problem, we have developed a 2D sequential inversion method of successively recovering the distributions of magnetization intensity and susceptibility and estimating the magnetization direction. The magnetization intensity distribution is first recovered from the total magnitude anomaly that is frequently transformed from the observed total-field anomaly and is invariant with the magnetization direction. With the recovered magnetization intensity distribution, we forward model the total-field anomalies caused by sources with different magnetization directions and calculate the correlations between the observed and predicted data. The orientation when the correlations attain a peak of maximum is defined as the optimal magnetization direction. Finally, the estimated magnetization direction helps to recover the susceptibility distribution by further inverting for total-field data. This method was tested by use of synthetic data and field data of two iron-ore deposits involving significant remanence, and all tests returned favorable results. The method obtaining the magnetization intensity and susceptibility distributions and an averaged magnetization direction made full use of the amplitude and phase information of magnetic anomalies, and it was more applicable for scenarios with a homogeneous magnetization direction.

show abstract

Airborne vector magnetics mapping of remanently magnetized banded iron formations at Rocklea, Western Australia

Cited by 27 publications

References 6 publications

Comprehensive approaches to 3D inversion of magnetic data affected by remanent magnetization

Comprehensive approaches to 3D inversion of magnetic data affected by remanent magnetization

Application of 3D magnetic amplitude inversion to iron oxide-copper-gold deposits at low magnetic latitudes: A case study from Carajás Mineral Province, Brazil

2D sequential inversion of total magnitude and total magnetic anomaly data affected by remanent magnetization

Contact Info

Product

Resources

About