Present and Future Geophysical Methods for Ni-Cu-PGE Exploration&lt;subtitle&gt;Lessons from McFaulds Lake, Northern Ontario&lt;/subtitle&gt;

Balch, S.J.; Mungall, James E.; Niemi, Jeremy

doi:10.5382/sp.15.2.11

Cited by 7 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…McFaulds Lake is the study area that is located in northwest Ontario, Canada. A highly magnetic ultramafic intrusion was emplaced within the Sachigo greenstone belt in the area known as the Ring of Fire (Balch, Mungall and Niemi ). The ultramafic intrusion is the host of Ni–Cu–PGE deposits in deeper parts and hosts chromite deposits in upper parts within magnetite and serpentine (Lin and Zhdanov ).…”

Section: Application To Field Magnetic Data Of Mcfaulds Lakementioning

confidence: 99%

A sigmoid stabilizing function for fast sparse 3D inversion of magnetic data

Rezaie

2019

Near Surface Geophysics

View full text Add to dashboard Cite

An interesting geological objective of quantitative interpretation of magnetic data is to find inverse models which can determine sharp geological interfaces below the surface. The stabilizing function in the Tikhonov parametric functional governs sparseness constraint in the recovered model. This paper introduces a novel stabilizer based on a sigmoid function which can provide non‐smooth models in the inversion of magnetic data efficiently. An inversion algorithm is developed based on the reweighted regularized conjugate gradient to get the solution of the inverse problem using this stabilizing function. The performance of the proposed algorithm is checked on two synthetic data sets and real aeromagnetic data from McFaulds Lake in Ontario, Canada, in comparison with the results of the minimum support stabilizing function. The inverse problem converges to the solution faster when the sigmoid stabilizing function is used instead of the minimum support stabilizing function.

show abstract

Section: Application To Field Magnetic Data Of Mcfaulds Lakementioning

confidence: 99%

A sigmoid stabilizing function for fast sparse 3D inversion of magnetic data

Rezaie

2019

Near Surface Geophysics

View full text Add to dashboard Cite

show abstract

“…Our study area is located within the central domain, where most of the known chromite deposits are located. Balch et al (2010) summarized a number of geophysical surveys from two Ni-Cu-PGE occurrences in the McFaulds Lake area. They present a qualitative interpretation of full gravity tensor data measured with the Bell Geospace system in the McFaulds area and conclude that tensor data provide an accurate outline of ultramafic units and iron formations.…”

Section: Geological Settingmentioning

confidence: 99%

“…The expected density contrast between ultramafic units and the lower density country rocks ranges from 0.1 to 0.4 g/cm 3 . A qualitative interpretation of aeromagnetic data is also presented by Balch et al (2010); no physical properties are given as the data were strictly used to map the geology. However, ultramafic rocks have high susceptibility and are expected to cause high amplitude magnetic anomalies similar to those observed in our data.…”

Section: Geological Settingmentioning

confidence: 99%

Interpretation of magnetic and gravity gradient tensor data using normalized source strength – A case study from McFaulds Lake, Northern Ontario, Canada

Beiki

Keating

Clark

2014

Geophysical Prospecting

View full text Add to dashboard Cite

In this paper, we present a case study on the use of the normalized source strength (NSS) for interpretation of magnetic and gravity gradient tensors data. This application arises in exploration of nickel, copper and platinum group element (Ni‐Cu‐PGE) deposits in the McFaulds Lake area, Northern Ontario, Canada. In this study, we have used the normalized source strength function derived from recent high resolution aeromagnetic and gravity gradiometry data for locating geological bodies. In our algorithm, we use maxima of the normalized source strength for estimating the horizontal location of the causative body. Then we estimate depth to the source and structural index at that point using the ratio between the normalized source strength and its vertical derivative calculated at two levels; the measurement level and a height h above the measurement level. To discriminate more reliable solutions from spurious ones, we reject solutions with unreasonable estimated structural indices. This method uses an upward continuation filter which reduces the effect of high frequency noise. In the magnetic case, the advantage is that, in general, the normalized magnetic source strength is relatively insensitive to magnetization direction, thus it provides more reliable information than standard techniques when geologic bodies carry remanent magnetization. For dipping gravity sources, the calculated normalized source strength yields a reliable estimate of the source location by peaking right above the top surface. Application of the method on aeromagnetic and gravity gradient tensor data sets from McFaulds Lake area indicates that most of the gravity and magnetic sources are located just beneath a 20 m thick (on average) overburden and delineated magnetic and gravity sources which can be probably approximated by geological contacts and thin dikes, come up to the overburden.

show abstract