Apparent Magnetic Susceptibility Research Articles

Verification of Geophysical Surveys by New Archaeological Excavations on the Grounds of the Middle La Tène Site of Němčice in 2021–2022

The Němčice site located in a strategic area of an agricultural plateau represents one of the most important archaeological sites in Moravia. Non-destructive archaeological surveys including a largescale magnetometer survey, field artefact collections, and metal detector surveys have been carried out there repeatedly over the past two decades. New archaeological excavations during a new project were focused on selected areas and situations identified during magnetometer prospection. The results of an archaeological investigation of the site using test pits confirmed settlement, glass-making and ritual activity under magnetic anomalies at the site. The new possibility of comparing uncovered sunken features and distributions of magnetic anomalies provided new feedback for a more precise interpretation of similar anomalies from magnetograms. An additional detailed apparent magnetic susceptibility measurement in situ showed another possibility for the application of the geophysical method during archaeological excavations. We were able to obtain additional information about the fills or possible post-depositional processes of various sunken features in the case of vertical profiles monitored by magnetic susceptibility meter measurements. The use and combination of various geophysical data has been beneficial in the case of an archaeological site as important as Němčice, and will continue to be so in future archaeological research of the site.

Evaluation of Multiple Linear Regression and Machine Learning Approaches to Predict Soil Compaction and Shear Stress Based on Electrical Parameters

This study investigated the relationships between the electrical and selected mechanical properties of soil. The analyses focused on comparing various modeling relationships under study methods that included machine learning methods. The input parameters of the models were apparent soil electrical conductivity and magnetic susceptibility measured at depths of 0.5 m and 1 m. Based on the models, shear stress and soil compaction were predicted. Neural network models outperformed support vector machines and multiple linear regression techniques. Exceptional models were developed using a multilayer perceptron neural network for shear stress (R = 0.680) and a function neural network for soil compaction measured at a depth of 0–0.5 m and 0.4–0.5 m (R = 0.812 and R = 0.846, respectively). Models of very low accuracy (R < 0.5) were produced by the multiple linear regression.

Identifying relict periglacial features in watershed landscape and deposits of Borisoglebsk Upland, Central European Russia

Watershed landscapes of the Central Russian Plain, which were subjected to the Late Pleistocene permafrost, bear witness to widespread cryogenic structuring. It is reflected both in semi-regular spots, blocks and polygons in soil and vegetation cover on arable fields and as vertically oriented wedge casts in surficial deposits. This study aimed to identify relict periglacial features in both the landscape and sedimentary sequence of the Borisoglebsk Upland to determine if there is a correspondence of these cast networks to the distribution of landforms and regular patterns of soil and vegetation cover. Combined interpretation of aerial and satellite multi-temporal imagery and detailed investigation of vertical cross-sections in gradually expanding geotechnical trenches including apparent magnetic susceptibility measurements allowed us to reveal and spatially correlate three generations of wedge casts, each buried by well-pronounced sedimentary units, and a specific bulbous type of cast. The type of cryogenesis, erosion and slope mass-movements changed from the Late Pleniglacial to Late Glacial, representing a good proxy in the watershed sedimentary cover for palaeoenvironmental reconstructions. However, regular polygonal patterns caused by these casts are almost erased in the modern topography whereas shallow dry gullies mostly inherit pre-Holocene wider linear depressions with no clear relationship to the buried cryogenic polygons.

How magnetic susceptibilities measured on outcrops can be used for modelling (and constraining inversions of) aeromagnetic data

Magnetic susceptibilities measured on outcrop are often assumed to be reasonable values to use when modelling aeromagnetic data. We have undertaken two exercises to understand how useful these measurements are for magnetic modelling. Estimates of apparent magnetic susceptibility can also be derived from aeromagnetic data by mathematical transformation if certain stringent conditions are satisfied. In the first exercise comparison of these two sets of values shows that when the measured values are below 1 × 10−3 SI, there is no correlation between the measured and apparent values. Above this value, the measured and estimated values agree to within a factor of 10, so these measured values can only be used as very rough constraints. In the second exercise, a database of outcrop measured magnetic susceptibilities was used to estimate a mean value for each lithology. When the mean of the measured values was used in our forward modelling exercise, we obtained a poor fit. However, when we inserted additional layers with larger susceptibilities that are represented on the histogram of a regional compilation of that lithology, the fit was satisfactory. In some cases, these additional layers were located in areas where there is relatively large variability in the magnetic susceptibility values measured on nearby outcrops. A large database of outcrop magnetic susceptibilities proved useful for providing a reasonable initial guess and the range of values that encompass the possible heterogeneities in each rock type.

Transformation of magnetic data to the pole and vertical dip and a related apparent susceptibility transform: Exact and approximate approaches

The dipolar character of magnetic data means that there is a high and a low associated with each source. The relative positions and sizes of these highs and lows vary depending on the magnetic latitude or the inclination of the earth’s magnetic field. One method for dealing with this complexity is to transform the data to what would be collected if the inclination were vertical (as at the magnetic pole), a process that is unstable at low magnetic latitudes. Unfortunately, remanent magnetization adversely impacts the success of this transformation. A second approach is to calculate the analytic-signal amplitude (ASA) of the data, which creates a single positive feature for each source or edge, with the shape being only weakly dependent on the inclination and the presence of remanent magnetization. The ASA anomalies can appear to be relatively broad, so features sometimes merge together on map views of the ASA. A subsequent transformation of the ASA using an appropriate transforming tilt angle can generate a magnetic field of a body that is at the pole and has a vertical dip. The transformation is exact for contacts when calculated from the first-order ASA, but the sign of the transformed data can be incorrect depending on whether you are over one edge or the other edge of a discrete source body. Another approximate transformation of the zeroth-order ASA does not have this issue and gives good results on synthetic data provided that any noise is handled appropriately. The resulting maps outline the magnetic source bodies and have amplitudes proportional to an apparent magnetic susceptibility. On field data from Black Hill, South Australia, the approximate transformation generates an image that is simple to interpret and enhances some features less obvious on other enhancements of the data.

Characterization of soil drainage using electromagnetic induction measurement of soil magnetic susceptibility

As a physical property of soil, magnetic susceptibility (MS) has been widely used to delineate soil drainage conditions over the past two decades, where all MS values were derived from laboratory measurements. In this paper, the ability of an electromagnetic induction (EMI) instrument, Geonics EM38, in in-field measurements of apparent magnetic susceptibility (MSa or κa) of topsoil was tested on six selected soil profiles having different drainage conditions. The MSa data, measured in both vertical and horizontal coil configurations of EM38, were then inverted using an iterative 1-D inversion procedure to calculate real volume MS of soil layers up to 1 m depth. Moreover, volume and mass-specific MS of the soil profiles were directly measured in laboratory by employing Bartington MS2C and MS2B sensors applied on core and dried soil samples, respectively, collected at the soil profiles. Comparing the results revealed that volume MS profiles derived from inversion of MSa data were positively correlated with MS profiles measured in laboratory, especially at topsoil. It was also found that MS values in poorly drained soil profile were lower than those of a well-drained profile. So, considering that EMI methods are fast, precise and cost-efficient, they would be preferred over conventional methods for delineating soil drainage conditions if using soil MS assessment is considered as soil drainage criteria.

In vivo assessment of anisotropy of apparent magnetic susceptibility in white matter from a single orientation acquisition

Multiple studies have reported a significant dependence of the effective transverse relaxation rate constant (R2*) and the phase of gradient-echo based (GRE) signal on the orientation of white matter fibres in the human brain. It has also been hypothesized that magnetic susceptibility, as obtained by single-orientation quantitative susceptibility mapping (QSM), exhibits such a dependence. In this study, we investigated this hypothesized relationship in a cohort of healthy volunteers. We show that R2* follows the predicted orientation dependence consistently across white matter regions, whereas the apparent magnetic susceptibility is related differently to fibre orientation across the brain and often in a complex non-monotonic manner. In addition, we explored the effect of fractional anisotropy measured by diffusion-weighted MRI on the strength of the orientation dependence and observed only a limited influence in many regions. However, with careful consideration of such an impact and the limitations imposed by the ill-posed nature of the dipole inversion process, it is possible to study magnetic susceptibility anisotropy in specific brain regions with a single orientation acquisition.

Magnetic characterization of paramagnetic reagents by particle tracking velocimetry.

Magnetic particle characterization determines the quality of magnetic particles and is of great importance in particle technology, drug delivery, cell separation, in vivo diagnostics, and other biomedical applications. The quality of the sample depends on the particle size, intrinsic magnetic properties of the particles, and the uniformity of these properties. A commercial particle tracking velocimeter was used to record and capture dark field images of particle trajectories in an applied isodynamic magnetic field. The calibrated particle size, magnetophoretic mobility, and additional image data were collected for each magnetic bead imaged. Using twenty-one different de-identified calibration beads and transmission electron microscopy to validate the vendor-reported particle size enabled the estimation of intrinsic magnetic properties, namely, apparent magnetic susceptibility and saturation magnetization, of individual paramagnetic particles. The distributions of volume magnetic susceptibility based on the magnetophoretic mobility and size of the particle for different magnetic beads were determined and displayed as two-parameter distributions. The measured apparent susceptibility and saturation magnetization were found to be directly proportional to the percentage of iron oxide in the reagent particles.

The Relationship between Soil Electrical Parameters and Compaction of Sandy Clay Loam Soil

Soil spatial variability mapping allows the delimitation of the number of soil samples investigated to describe agricultural areas; it is crucial in precision agriculture. Electrical soil parameters are promising factors for the delimitation of management zones. One of the soil parameters that affects yield is soil compaction. The objective of this work was to indicate electrical parameters useful for the delimitation of management zones connected with soil compaction. For this purpose, the measurement of apparent soil electrical conductivity and magnetic susceptibility was conducted at two depths: 0.5 and 1 m. Soil compaction was measured for a soil layer at 0–0.5 m. Relationships between electrical soil parameters and soil compaction were modelled with the use of two types of neural networks—multilayer perceptron (MLP) and radial basis function (RBF). Better prediction quality was observed for RBF models. It can be stated that in the mathematical model, the apparent soil electrical conductivity affects soil compaction significantly more than magnetic susceptibility. However, magnetic susceptibility gives additional information about soil properties, and therefore, both electrical parameters should be used simultaneously for the delimitation of management zones.

Updated tectonic terrane boundaries of Botswana determined from gravity and aeromagnetic data

We used existing high-resolution gravity and aeromagnetic data to map the crustal units underneath Botswana. The thick sedimentary cover in this region has always been a challenge to understand the geological and tectonic configuration of unexposed crustal terranes using traditional geological methods. We utilized a standard physical mapping technique to convert previously obtained gravity and aeromagnetic data into apparent density and magnetic susceptibility maps, respectively, of the crustal tectonic terranes. Then, the derived maps were fused into a single apparent physical map to facilitate its geotectonic interpretation. The results showed that most of the tectonic boundaries were inaccurately mapped due to limited availability of high-resolution geophysical information. Moreover, we found that some terranes were missing from the current tectonic map. We used the apparent physical property map and the basement rocks information from literature to significantly update the tectonic map of Botswana, which shows the spatial extent of the geological units beneath the Kalahari sedimentary cover. The new map gives an insight into the geodynamics of Botswana crust.

Depth Sensitivity of Apparent Magnetic Susceptibility Measurements using Multi-coil and Multi-frequency Electromagnetic Induction

Apparent magnetic susceptibility (MSa) as recorded by electromagnetic induction (EMI) instruments could offer relevant information about non-soil subsurface features. It is less affected by natural soil properties than its prominent counterpart, i.e., apparent electrical conductivity (ECa). Hence, MSa is generally a promising approach to investigate artificial inclusions and structures in soil. However, while the origin depth of EMI based ECa is widely accepted, the depth sensitivity (DS) of MSa measurements remains poorly understood. The depth interpretation of MSa is particularly challenging due to negative values especially for objects that are randomly distributed over different depths. Here we assessed the performance of both multi-coil (MC) and multi-frequency (MF) EMI sensors for identifying and determining the DS of MSa measurements in shallow soils through detection of buried small targets of known conductivity. Two experiments were conducted in a sandy loam podzolic soil in western Newfoundland, Canada. Materials of different conductivities, including metal and plastic targets, were buried at depths between 20 and 80 cm. Three inter-coil separations (32, 71 and 118 cm) of the MC sensor and four factory-calibrated frequencies (18, 38, 49 and 80 kHz) of the MF sensor were tested in both horizontal and vertical coil orientations. The MC sensor clearly detected all four metal targets from three coil separations in both coil orientations while the MF sensor identified more anomalies than targets limiting its information value. Based on the measurements from MC and the theoretical DS function, a criterion was developed and validated to assess the potential depth origin of MSa. We found that negative or less than the background values occur, if the depth of the target is shallower than 0.36 times the coil distance of the employed EMI sensor. According to this criterion, the depth origins of metallic targets were correctly identified under the assumption of low induction numbers, even if values were negative.

Field Proximal Soil Sensor Fusion for Improving High-Resolution Soil Property Maps

Mapping soil properties, using geostatistical methods in support of precision agriculture and related activities, requires a large number of samples. To reduce soil sampling and measurement time and cost, a combination of field proximal soil sensors was used to predict and map laboratory-measured soil properties in a 3.4-ha pasture field in southeastern Brazil. Sensor soil properties were measured in situ on a 10 × 10-m dense grid (377 samples) using apparent electrical conductivity meters, apparent magnetic susceptibility meter, gamma-ray spectrometer, water content reflectometer, cone penetrometer, and portable X-ray fluorescence spectrometer (pXRF). Soil samples were collected on a 20 × 20-m thin grid (105 samples) and analyzed in the laboratory for organic C, sum of bases, cation exchange capacity, clay content, soil volumetric moisture, and bulk density. Another 25 samples collected throughout the area were also analyzed for the same soil properties and used for independent validation of models and maps. To test whether the combination of sensors enhances soil property predictions, stepwise multiple linear regression (MLR) models of the laboratory soil properties were derived using individual sensor covariate data versus combined sensor data—except for the pXRF data, which were evaluated separately. Then, to test whether a denser grid sample boosted by sensor-based soil property predictions enhances soil property maps, ordinary kriging of the laboratory-measured soil properties from the thin grid was compared to ordinary kriging of the sensor-based predictions from the dense grid, and ordinary cokriging of the laboratory properties aided by sensor covariate data. The combination of multiple soil sensors improved the MLR predictions for all soil properties relative to single sensors. The pXRF data produced the best MLR predictions for organic C content, clay content, and bulk density, standing out as the best single sensor for soil property prediction, whereas the other sensors combined outperformed the pXRF sensor for the sum of bases, cation exchange capacity, and soil volumetric moisture, based on independent validation. Ordinary kriging of sensor-based predictions outperformed the other interpolation approaches for all soil properties, except organic C content, based on validation results. Thus, combining soil sensors, and using sensor-based soil property predictions to increase the sample size and spatial coverage, leads to more detailed and accurate soil property maps.

Open-Loop Orientation Control Using Dynamic Magnetic Fields

Remote magnetic control of soft magnetic objects has been limited to 2D orientation and 3D position. In this letter, we extend the five degree-of-freedom (5-DoF) control approach to full 6-DoF. We prove that 6-DoF control is possible for objects that have an apparent magnetic susceptibility tensor with unique eigenvalues. We further show that the object’s orientation can be specified with a dynamic magnetic field and can be controlled without orientation feedback.The theory is demonstrated by rotating a soft magnetic object about each of its principle axes using a metronome like dynamic field.

Aeromagnetic modelling of Precambrian subsurface structures of the Tasiast area, NW Mauritania

Abstract The NW sector of Mauritania represents the Archaean province of the Reguibat Shield. It is mainly composed of the typical Archaean cratonic association of granitoid gneisses, greenstone belts and granites. The greenstone belts contain high mineral potential, mainly gold. This is particularly the case of the Chami Greenstone Belt, which hosts the large Tasiast gold mine. The gold deposits are hosted along a NS oriented shear zone with a surface of 70 × 15 km 2 . In this study, a subsurface structural model is proposed based on the application of suitable computations on a high-resolution reduced-to-the-pole aeromagnetic anomaly map of the northern Chami area. Upward continuations, apparent magnetic susceptibility, directional derivatives, analytical signal, 3D Euler deconvolution and spectral analyses were performed to build this model. They were used to decipher the main evidenced structural features with the main NNE–SSW, NW–SE and ∼120° N directions, identified on most all computed maps combined with in situ measurements. They probably correspond to mafic dykes, faults and shears rooted up to 5 km in depth, particularly to the north, SW and NE, and southwards and westwards by spectral analyses and 3D Euler deconvolution, respectively. The basement is deeper towards the west and south and crops out towards the NE in agreement with the geological observations. In addition, the high values of magnetic susceptibility ( χ m ) measured in situ on banded iron formations (25.7–35 × 10 −3 SI) SW of Akjoujt could be the origin of metallotect sources associated with magnetic minerals for exploration of gold-bearing and base metals.

ESTIMATION OF SOURCE PARAMETERS IN IBADAN, SOUTH – WESTERN NIGERIA USING DIGITIZED AEROMAGNETIC DATA

Airborne magnetic data covering geographical latitudes of 7000‟N to 7030‟N and longitudes of 3 30′E to 4 00′E within Ibadan area were obtained from Nigeria Geology Survey Agency. The data were ana-lyzed to map the sub surface structure and the source parameters were deduced from the quantitative and qualitative interpretation of magnetic data. The upward continuation technique was used to de-emphasize short – wavelength anomaly while the depth to magnetic sources in the area was deter-mined using local wavenumber technique, the analytic signal was also employed to obtain the depths of the magnetic basement. Analysis involving the local wavenumber, upward continuation and appar-ent magnetic susceptibility techniques significantly improves the interpretation of magnetic data in terms of delineating the geological structure, source parameter and magnetic susceptibility within Iba-dan area.. These depth ranges from 0.607km to 2.48km. The apparent susceptibility map at the cut-off wavelength of 50 m ranges from -0.00012 to 0.00079 which agree with the susceptibility value of some rock types; granite gneiss, migmatite biotite gneiss, biotite muscovite granite, hornblende granite, quartz and schists. The result of the local wavenumber suggests variation along the profiles in the surface of magnetic basement across the study area.

Multi-frequency Electromagnetic Induction Survey for Archaeological Prospection: Approach and Results in Han Hangu Pass and Xishan Yang in China

This study presents the potential of multi-frequency electromagnetic induction (EMI) in archaeology. EMI is currently less employed for archaeological prospection with respect to other geophysical techniques. It is capable of identifying shallow subsurface relics by simultaneously measuring the apparent electrical conductivity (ECa) and apparent magnetic susceptibility (MSa). Moreover, frequency sounding is able to quantify the depths and vertical shapes of buried structures. In this study, EMI surveys with five frequencies were performed at two heritage sites with different geological conditions: Han Hangu Pass characterized by cinnamon soil and Xishan Yang by sandy loams. In the first site, high ECa values were observed with variations in depth correlated to archaeological remains. Moreover, electromagnetic anomalies related to an ancient road and five kiln caves were identified. In the second site, an ancient tomb, indicating extremely low ECa and high MSa, was discovered. Its electromagnetic properties are attributed to the cavity and ferroferric oxides.

Joint Inversion of Apparent Conductivity and Magnetic Susceptibility to Characterize Buried Targets

A good knowledge of the underground space is needed in urban planning. The main objects found buried are water and sewage pipes, cables, and contaminants storage tanks. Through the inversion of inductive electromagnetic data, we can obtain parameters like depth, position, and radius of these targets. Here, we show a joint inversion approach of apparent conductivity and magnetic susceptibility using data collected at the IAG/USP test site. The model employed assumes three coils (transmitter, receiver, and target/conductor) and relates the electromotive force, through the mutual inductance that occurs between the pairs of transmitter–receiver and conductor–receiver coils, to the acquired conductivity and susceptibility data. The achieved adjustment between field and calculated data indicates that, despite the simplicity of the model, it is a good representation of the conductors, increasing the results of the inversion process. The inversion algorithm is based on the controlled random search algorithm, which presented to be quite stable with electromagnetic data. The main advantage of the proposed approach is the relatively fast inversion process that showed better results than the traditional qualitative interpretation usually applied to this kind of investigation, being promising for noninvasive target characterization and having application in geotechnical studies.

Temperature-dependent hysteresis effects on EM induction instruments: An example of single-frequency multi-coil array instruments

Non-invasive electromagnetic (EM) induction has been used in agriculture, earth science and archaeology. This is because the apparent electrical conductivity (ECa or quadrature response – mSm−1) and the apparent magnetic susceptibility (in-phase response – ppt) which they measure are related to soil properties such as clay, soil mineralogy, salinity and soil moisture as well as buried metal objects. Although the accuracy issues of the single-coil array EM38 meter have been widely discussed, the accuracy issues of the next generation, multi-coil (perpendicular-PRP and horizontal-HCP) array DUALEM meter, particularly the instrument drift, have little been reported. In this study, the diurnal drifts of a DUALEM-421S and a DUALEM-21S were studied at single locations (for a 24h period) and along a 480-m transect (at five typical operation times). Based on the experiment results of the two DUALEM instruments, it was found that the ECa readings of the PRP arrays were more stable than those of the HCP arrays. The reverse was true for in-phase measurements. Specifically, during the diurnal cooling and heating phases, ECa measurements of the HCP arrays and in-phase PRP arrays showed different correlations with ambient temperature, which can be defined as instrument-specific and temperature-dependent hysteresis effects. In addition, the stability of ECa and in-phase measurements increased with array length and was much less compared to the theoretical values. It was suggested a similar experiment should be conducted for the DUALEM instruments before the DUALEM surveys and repeated DUALEM surveys for mapping the spatio-temporal variations in soil properties should be carried out at the similar temperature (i.e., similar ambient temperature and within the same warming or cooling phase). In addition, shading the instruments with non-conductive thermal insulation should be adopted and drift correction procedures should be applied to improve the quality of the measurements of the EM instruments.

Magnetic and Gravity Gradiometry Framework for Mesoproterozoic Iron Oxide-Apatite and Iron Oxide-Copper-Gold Deposits, Southeast Missouri

High-resolution airborne magnetic and gravity gradiometry data provide the geophysical framework for evaluating the exploration potential of hidden iron oxide deposits in Mesoproterozoic basement rocks of southeast Missouri. The data are used to calculate mineral prospectivity for iron oxide-apatite (IOA) ± rare earth element (REE) and iron oxide-copper-gold (IOCG) deposits. Results delineate the geophysical footprints of all known iron oxide deposits and reveal several previously unrecognized prospective areas. The airborne data are also inverted to three-dimensional density and magnetic susceptibility models over four concealed deposits at Pea Ridge (IOA ± REE), Boss (IOCG), Kratz Spring (IOA), and Bourbon (IOCG). The Pea Ridge susceptibility model shows a magnetic source that is vertically extensive and traceable to a depth of greater than 2 km. A smaller density source, located within the shallow Precambrian basement, is partly coincident with the magnetic source at Pea Ridge. In contrast, the Boss models show a large (625-m-wide), vertically extensive, and coincident dense and magnetic stock with shallower adjacent lobes that extend more than 2,600 m across the shallow Precambrian paleosurface. The Kratz Spring deposit appears to be a smaller volume of iron oxides and is characterized by lower density and less magnetic rock compared to the other iron deposits. A prospective area identified south of the Kratz Spring deposit shows the largest volume of coincident dense and nonmagnetic rock in the subsurface, and is interpreted as prospective for a hematite-dominant lithology that extends from the top of the Precambrian to depths exceeding 2 km. The Bourbon deposit displays a large bowl-shaped volume of coincident high density and high-magnetic susceptibility rock, and a geometry that suggests the iron mineralization is vertically restricted to the upper parts of the Precambrian basement. In order to underpin the evaluation of the prospectivity and three-dimensional models, an extensive statistical summary of density and apparent magnetic susceptibility measurements is presented that includes data on several hundred samples taken from the deposits, altered wall rocks, and unaltered country rocks.

The whole-brain pattern of magnetic susceptibility perturbations in Parkinson's disease.

Although iron-mediated oxidative stress has been proposed as a potential pathomechanism in Parkinson's disease, the global distribution of iron accumulation in Parkinson's disease has not yet been elucidated. This study used a new magnetic resonance imaging contrast, quantitative susceptibility mapping, and state-of-the-art methods to map for the first time the whole-brain landscape of magnetostatic alterations as a surrogate for iron level changes in n = 25 patients with idiopathic Parkinson's disease versus n = 50 matched controls. In addition to whole-brain analysis, a regional study including sub-segmentation of the substantia nigra into dorsal and ventral regions and qualitative assessment of susceptibility maps in single subjects were also performed. The most remarkable basal ganglia effect was an apparent magnetic susceptibility increase-consistent with iron deposition-in the dorsal substantia nigra, though an effect was also observed in ventral regions. Increased bulk susceptibility, additionally, was detected in rostral pontine areas and in a cortical pattern tightly concordant with known Parkinson's disease distributions of α-synuclein pathology. In contrast, the normally iron-rich cerebellar dentate nucleus returned a susceptibility reduction suggesting decreased iron content. These results are in agreement with previous post-mortem studies in which iron content was evaluated in specific regions of interest; however, extensive neocortical and cerebellar changes constitute a far more complex pattern of iron dysregulation than was anticipated. Such findings also stand in stark contrast to the lack of statistically significant group change using conventional magnetic resonance imaging methods namely voxel-based morphometry, cortical thickness analysis, subcortical volumetry and tract-based diffusion tensor analysis; confirming the potential of whole-brain quantitative susceptibility mapping as an in vivo biomarker in Parkinson's disease.