Electrical Anomalies Research Articles

Electrical conductivity anomalies study

Anomalous currents in a well-conducting body arise due to local electromagnetic induction inside the anomalous body, as well as due to conductive redistribution (and concentration) of currents induced in the host medium on a large territory equal to the external source size. The local induction generates the so-called anomaly of geomagnetic variations of the magnetic or inductive type. Its characteristic property is that the secondary anomalous field cannot be greater than the primary normal field of geomagnetic variations. However, in some places on the earth’s surface, the normalized anomalous fields are greater than 1. Analytical solution of the EM induction problem for circular cylinder yields the physical explanation of two types of anomalous geomagnetic fields. The first term (proportional to the normal electric field E0) describes the conductive anomaly type, the second term (proportional to the normal magnetic field B0) describes the inductive anomaly type. The conductive type usually is much greater than the inductive one. The normalized anomalous field of the conductive type is not limited to 1 or any other value. It is proportional to two functions: V(T) — the non-decreasing function of the period T (0≤V≤1, V=1 corresponds to DC) which describes the degree of filling of the conductor by anomalous currents (result of the skin effect inside the anomaly) and the normal impe­dance of inclosing cross-section — the decreasing function of the period. Product of these functions has a maximum at some period T0. The position T0 is closely related to the total lengthwise conductance G[S×m] of the anomalous body, that is, the scale of the anomaly. On the period T0, the anomalous fields and the induction vector become real C=Cu and the imaginary induction vector Cv passes through zero changing sign. Thus, the spectral properties of the geomagnetic response functions were studied for two-dimensional anomalies with a generalization to three-dimensional conductors with varying cross-section. 18 crustal electrical conductivity anomalies were considered and their integral lengthwise conductance G was obtained. At all anomalies, the G values turn out to be in a relatively narrow range G=(1—8)·108 S∙m; this has geophysical significance.

Multimode Control for Power Quality Improvement in an Electronically Coupled Distributed Generation Unit Under Grid Connected and Autonomous Modes

This paper develops a new multimode control strategy for power quality (PQ) improvement in distributed generation (DG) units that employs a voltage source converter (VSC) as the electronic interface medium. The devised control strategy seamlessly operates for both the grid connected (GC) and autonomous/stand-alone (SA) modes of microgrid (MG). A novel computationally efficient comb-filter driven discrete time oscillator is developed for current reference generation (CRG) under GC operation. It constitutes a cluster of zeros to introduce notch peaks at integer multiples of the fundamental frequency thereby ensuring improved harmonic rejection capability. Consequently, it ensures unconditionally balanced and sinusoidal grid currents with improved PQ to comply with grid interconnection codes prescribed in the IEEE std-519 and std-1547 even under electrical anomalies. In the SA mode, the CRG scheme is developed in a stationary reference frame with an improved vector proportional integral (VPI) compensator. Despite the uncertainty of load parameters, the proposed VPI guarantees zero steady-state error and superior transient response. A finite state machine-based synchronization framework is proposed to ensure secure and seamless transfer of MG between GC and SA even under disturbances. The practical viability of the proposed multimode control has been demonstrated by applying various switching rules in both GC and SA modes of MG operation.

Chiral anomalies in three-dimensional spin-orbit coupled metals: Electrical, thermal, and gravitational anomalies

Chiral anomalies in three-dimensional spin-orbit coupled metals: Electrical, thermal, and gravitational anomalies

Magnetotelluric investigations at Andean volcanoes: Partial melt or saline magmatic fluids?

Knowledge of the architecture of active magmatic systems is important for both volcanic hazard assessment and evaluating potential geothermal energy production and metals recovery from magmatic fluids. Increasingly, magmatic systems are imaged using the magnetotelluric method to detect electrically conductive partial melt and/or saline magmatic fluid reservoirs. We review recent magnetotelluric studies at eight Andean volcanoes, revealing electrical conductivity anomalies with variable magnitudes and locations. Six of the studied volcanoes exhibit three main electrical conductivity anomalies, located at shallow (<3 km), intermediate (≈5 km), and deep (>10 km) depths. The shallow anomalies are often thin and laterally extensive, consistent with clay cap alteration layers, while the deep anomalies are generally interpreted as partial melt reservoirs. The intermediate depth anomalies, although also often attributed to partial melt, have less clear origins. By analysing laboratory-derived electrical conductivity relationships, we show that the intermediate depth anomalies are generally most consistent with saline magmatic fluids stored in porous rock. However, other geophysical and petrological data suggest that localised partial melt also exists at intermediate depths. Therefore, the intermediate depth anomalies likely represent mixed melt and saline magmatic fluid systems, such as those responsible for forming magmatic-hydrothermal alteration zones and copper porphyry deposits. At individual volcanoes, refining the generalised three layer model proposed here by using additional geophysical or petrological data is key to constraining the resources and/or hazard potential of the magmatic system.

Inversion of ERT-3D data using PSO and weighting functions

In the last decade, a new data acquisition technique has emerged in 3D electrical resistivity tomography studies, where the target to study is beneath a structure such as a building and it is not possible to use the traditional technique. This is a very common scenario when investigating urban areas or archaeological sites. The technique, called Perimeter Data Acquisition (PDA) in this paper, allows the acquisition of irregularly distributed data beneath structures. Although electrical anomalies can be detected, the solution does not correctly determine their vertical location because of the irregular distribution of the data and the lack of data towards the central portion of the survey region limited by the electrodes.The methodology presented here aims to improve the calculation of the vertical location of the anomalous bodies in the subsoil using weighting functions in conjunction with a stochastic inversion method called Particle Swarm Optimization (PSO). Three weighting functions defined from the theoretical depth of the arrays and the resistivity standard deviation were tested by using synthetic models and comparing the solutions between them and with non-weighted solutions. Finally, the algorithm and weighting functions were applied on a case study to compute the vertical location of a cavern beneath a Mayan pyramid.The results indicate that when using the PDA technique, it is necessary to employ a weighting function to obtain an acceptable and reasonable solution. It is found that the weighting function defined from the resistivity standard deviation allowed to determine with the least error the vertical characteristics of the anomalous bodies.

Preliminary study of radio frequency waves in hypervelocity impact plasma

Orbital debris and meteoroids can cause mechanical and electrical anomalies by impacting spacecraft. Although mechanical damage tends to occur only from particles with masses >10−3g, electrical damage can be a result of hypervelocity (> 10 km/s) impacts (HVI) even with smaller particles. In HVI, the projectile speed exceeds the speed of sound in the material and has enough energy to create plasma by ionizing the material near the surface, which can then emit radio frequency (RF) waves.In this paper, we conduct a preliminary study on the characteristics of impact-generated RF emission with the ultimate goal of building an RF predictive model for risk assessment of HVI electrical effects that can damage spacecraft. First, we introduce wavelet analysis as a method for denoising and quantifying the total RF signal energy. An appropriate mother wavelet and the number of decomposition levels are selected using a synthetic signal. Second, the total energy of the RF emission is calculated using Parseval's theorem. Results suggest that the total RF signal energy is proportional to the energy flux of the impactor. Finally, spectrograms of the RF emission are analyzed to characterize features that can be used in the future to predict impacts that can cause electrical damage to satellites.

Self-Potential as a Tool to Monitor Redox Reactions at an Ore Body: A Sandbox Experiment

Ore bodies generate natural electrical fields that are measurable at the ground surface. The ground surface signature of this electrical field is called a self-potential anomaly. We developed a sandbox experiment to monitor the evolution of a self-potential anomaly associated with redox processes mediated by bacterial activity at the surface of a buried metallic object crossing the water table. A Bio-Electrochemical Cell (BEC) is formed by a metal bar connecting the upper, oxygen-rich, part of the tank and an aquifer containing an electron donor in the form of acetate. The self-potential response was observed during a period of 327 days. The tomography of the self-potential signature confirms that self-potential tomography is able to locate the metallic target acting as a BEC. In addition, we performed redox potential, pH, and electrical potential measurements over a vertical cross-section of the tank at several time steps to obtain an idea of where the redox front is located. The distributions of the redox potential and pH further demonstrated the development of the oxidation-reduction chemical processes facilitated by the BEC as bacterial communities developed around the metallic bar. The electrical potential anomaly shows that the bacterial communities followed a short period of exponential growth, then a longer period of a sustained population. These results demonstrate the usefulness of the self-potential method in monitoring redox processes at the surface of a buried ore body. Further works will need to combine such self-potential anomalies with induced polarization anomalies through joint inversion.

Characterization of Surface–Borehole Transient Electromagnetic Response in Electrical Anisotropic Media

When encountering sedimentary rocks with obvious laminations or fracture development zones, the conductivity of the conductive medium in different directions will change significantly, and the subsurface medium will exhibit macroscopic conductivity anisotropy. To analyze the impact of electrical anisotropy on the surface–borehole transient electromagnetic exploration method, we used the finite element method to investigate the electrical anisotropy surface–borehole transient electromagnetic three-dimensional (3D) forward algorithm, in which we used a tetrahedral mesh to spatially discretize the time–domain Maxwell equation. Then, we discretized it using the second-order backward Eulerian difference method, and we obtained the fields through the PARDISO solver. The validity and correctness of the algorithm were verified through comparison of a one-dimensional (1D) anisotropic model, a complex three-dimensional (3D) isotropic model, and a three-dimensional (3D) anisotropic half-space model. A typical anisotropic geological model was constructed to analyze the effects of anisotropic strata and anomalies in the different principal axis directions on the surface–borehole transient electromagnetic response. The results show that the response of the anisotropic medium is related to the direction of the transmitting source, and the response pattern is complex and volatile. The electrical anisotropic anomaly does affect the amplitude, which should be given special attention when performing surface–borehole transient electromagnetic inversion interpretation.

Experimental study on the kinetics of magnesiohornblende dehydration and its implications

Abstract Magnesiohornblende dehydration was studied using both high-temperature thermogravimetric analysis and high-pressure differential thermal analysis (HP-DTA). The high-temperature thermogravi-metric analysis results revealed that magnesiohornblende dehydration at high temperatures could be divided into three steps: 848–1058, 1058–1243, and 1243–1473 K, and each step followed an n-order reaction (Fn). The dehydration process is characterized by an oxidation-dehydrogenation mechanism, and the dehydration of the last step can be explained as the direct decomposition of the hydroxyl groups connected to the magnesium ions. The HP-DTA of magnesiohornblende dehydration under pressures of 0.5, 1.0, 2.0, and 3.0 GPa revealed the occurrence of two endothermic peaks, indicating that the dehydration occurs in two steps at high temperature and pressure. Our experimental results reveal that during subduction, the fluid released during the dehydration of magnesiohornblende may trigger earthquakes and cause high electrical conductivity anomalies in the subduction zones.

The electrical conductivity of granite: The role of hydrous accessory minerals and the structure water in major minerals

The electrical conductivity of granitic rocks (granitoids) is crucial to understand the rock composition, physiochemical state and structure of the crust. However, it is not clear how the conductivity of granitoids is affected by the incorporated water in major minerals and hydrous accessory minerals. Here, we measured the electrical conductivity of two natural granites and two synthetic aggregates compositionally similar to the granites at temperatures of 573–1273 K and pressures of either ambient pressure or 1 GPa. No mineral preferred orientation was observed for the natural samples. The hydrous accessory minerals in the samples, including muscovite, biotite and amphibole, start to dehydrate at about 700 K at ambient pressure, but barely affect the bulk conductivity. The increase in conductivity of granite by more than half orders of magnitude at 1273 K and 1GPa indicated the onset of melting due to the dehydration of biotite. The conductivities of synthetic aggregates are higher than the granite samples, suggesting that the structural water in feldspars could influence, to a moderate degree, the conductivity of granite. We combined the effect of modal composition and structural water on the conductivity of granite and derived a maximal electrical conductivity of a granitoid at different geological settings. The maximal conductivity can be 0.004 ± 0.0001 S/m at 60 km under orogens, over one order of magnitude higher than a cratonic crust. The maximal conductivity provides an upper limit for interpreting the electrical anomalies in the crust.

Investigation of buried karst sinkholes under a bog using ground penetrating radar (GPR) and electrical resistivity tomography (ERT)

AbstractActive evaporite karst processes in the Baltic states are associated with a few relatively small regions where gypsum rocks can be found close to the Earth's surface. One of these areas lies in the vicinity of the Pandu bog. However, such a possibly active karst region, which is covered by peat and in which the mapping of karst formations is complex, has not been previously investigated. In this study, we present a buried and peat‐filled karst cover‐collapse sinkhole mapping approach that involves a combination of ground‐penetrating radar (GPR), electrical resistivity tomography (ERT) and conventional boreholes. A detailed map of the bog's substratum topography was constructed from a geophysical surveying dataset. It reveals 15 distinctly expressed sinkholes with diameters of several tens of metres. Overall, 140 potential sinkholes were also mapped using remote sensing data in the vicinity of the bog. Higher electrical resistivity anomalies were identified inside the peat; they coincide with scatter‐free zones in GPR data and water layers in boreholes. Highly disturbed internal peat layering was also detected in these sinkholes. It is suggested that these water layers and disturbed peat layering may have formed due to the subsidence of the lower peat layers, and thus they represent relatively younger sinkholes. This is also supported by evidence from orthophoto maps, which showed the formation and disappearance of surficial lakes and depressions on the bog surface. Our results revealed the presence of active and widespread karst processes under the bog that have not been previously noticed despite the fact that they have implications for the assessment of geohazards in this area.

Anomaly Detection in Automatic Meter Intelligence System Using Positive Unlabeled Learning and Multiple Symbolic Aggregate Approximation.

With the development of automatic electrical devices in smart grids, the data generated by time and transmitted are vast and thus impossible to control consumption by humans. The problem of abnormal detection in power consumption is crucial in monitoring and controlling smart grids. This article proposes the detection of electrical meter anomalies by detecting abnormal patterns and learning unlabeled data. Furthermore, a framework for big data and machine learning-based anomaly detection framework are introduced. The experimental results show that the time series anomaly detection for electric meters has better results in accuracy and time than the expert alternatives.

Small effect of partial melt on electrical anomalies in the asthenosphere.

High conductivity anomalies in the shallow mantle are frequently attributed to minor partial melt (basalt or carbonatite) in the olivine-dominated peridotites. Conductivity of a melt-mineral mixture depends on the configuration of melt that could be affected by grain size of the constitutive mineral(s), but this has rarely been explored. Here, we provide experimental evidence using a conductive carbonatite analog and olivine that the bulk conductivity decreases systematically with increasing olivine grain size. The required amount of melt for producing the geophysically resolved high conductivities in the asthenosphere is much greater than previously assumed. We suggest that the effect of partial melt on many conductive regions in the asthenosphere is small. Instead, the electrical anomalies (especially those away from mid-ocean ridges) originate more likely from subsolidus solid assemblages in the upper mantle. This reconciles well the geochemical and petrological constraints of the shallow mantle with its geophysically determined electrical properties.

Donbas conductivity anomaly in the Karpinsky Swell

Donbas Foldbelt (DF) and Karpinsky Swell (KS) are contiguous parts of a system of elongated sedimentary basins forming lineament from Poland through Pripyat Trough in Belarus, the Dnieper-Donets Basin (DDB) and DF in Ukraine, KS in Russia, across the Caspian Sea, through Mangyshlak in Turanian plate in Asia. In DF, the Mesozoic-Cenozoic sediments were raised, and subsequent erosion exposed the Carboniferous coal-bearing strata. In contrast to DF, the Paleozoic rocks in KS are covered by 1—3 km thick sediments of Mesozoic-Cenozoic age; productive structures of the earlier age cannot be confidently studied in KS by geological methods. So, geophysical methods are the promising approach for the KS deep structure studies. This work is devoted to electromagnetic (EM) studies of the electrical conductivity of rocks by the methods of magnetic variation profiling (MVP) and magnetotelluric sounding (MTS). Previously [Rokityansky, Tereshyn, 2022], we described the results of the EM research on DF in detail. MVP reveals the intense Donbas electrical Conductivity Anomaly (DCA) running along the main anticline of the folded Donbas. DCA parameters: maximum possible depth of the anomalous currents center h=18±2 km. Frequency response maximum Т0≈3600 s yields the total longitudinal conductance G=(8±2)∙108 S∙m. 70 MTS at periods 0.1—3000 s yield two conductive stripes, with the upper edge varying from 0.3 to 5 km. The stripes are parallel to the DCA axis and are considered as part of DCA. A very large value of G suggests that the anomalous body extends to some considerable depth. The DCA axis spatially coincides with an intense (up to 90 mW/m2) deep heat flow anomaly. Thus, the nature of the DCA lower part can be a partial melting. Theoretical estimates show that intense anomalous fields of geomagnetic variations arise over highly elongated conductors. Therefore, there is reason to expect that the anomaly continues eastward. We found two MTS profiles crossing the Karpinsky swell, and under both profiles strong conductivity anomalies are clearly seen. We re-interpreted original data and presented parameters of all 3 anomalies in an identical style. The main conclusion: the anomaly parameters on the three profiles are approximately the same, and one can assume with a high probability the existence of a single anomaly of electrical conductivity in the Donbas and Karpinsky Swell with a common length of more than 500 km and longitudinal conductance G≈8×108 S×m.

A Review of Subsurface Electrical Conductivity Anomalies in Magnetotelluric Imaging.

After 70 years of development, magnetotelluric (MT), a remote sensing technique for subsurface electrical resistivity imaging, has been widely applied in resource exploration and the deep tectonic evolution of the Earth. The electrical resistivity anomalies and their quantitative interpretation are closely related to or even controlled by the interconnected high-conductivity phases, which are frequently associated with tectonic activity. Based on representative electrical resistivity studies mainly of the deep crust and mantle, we reviewed principal electrical conduction mechanisms, generally used conductivity mixing models, and potential causes of high-conductivity including the saline fluid, partial melting, graphite, sulfide, and hydrogen in nominally anhydrous minerals, and the general methods to infer the water content of the upper mantle through electrical anomaly revealed by MT.

Monitoring the efficiency of electro-kinetic soil remediation process with geophysical surveying method

Geoelectric surveying is a useful method of non-invasive investigation (e.g.: for the purpose of space delineation or time dependant monitoring) of subsurface contaminants. The measured onsite electrical resistivity values are a function of certain soil parameters and the electric properties of the contaminant. With executing time domain field surveys before and after the remediation process its efficiency on contamination removal can be valorized.In this study we present a field case to illustrate the applicability of the geoelectric method for monitoring the efficiency of hydrocarbon removal and highlighting the problems of interpretation due to change of soil parameters and various hydrocarbon composition. Due to the side effects of electro-kinetic soil remediation process some soil parameters affecting the electrical resistivity are also changed. Therefore, when interpreting the data the of field survey one must be able to separate the geoelectric response of the remnant contamination from the changed soil parameters. The paper presents a multilevel interpretation method when the measured electrical resistivity data were correlated with the time-domain results of detailed soil sample analytics including particle size distribution, physical properties, and chemical composition. As a result we were able to separate the time domain geoelectric effects of the soil from the geoelectric response of the hydrocarbon contamination and we could correlate the electrical resistivity anomalies with the integrated effects of hydrocarbon content and changes in the soil due to the remediation treatment.

An Automatic Detection Framework for Electrical Anomalies in Electrified Rail Transit System

Automatic electrical anomaly detection for high-speed rail (HSR) is essential to ensure the safe and efficient operation of HSR. In this article, a novel anomaly detection method is proposed to rapidly identify typical anomalies and detect unknown anomalies in train-grid electrical coupling system (TGECS). The framework of the method consists of feature extraction, pre-classification and re-identification. First, the raw electrical signal is processed by Hilbert transform (HT) to obtain the instantaneous envelope. Second, the one-dimensional (1-D) convolutional neural network (CNN) is adopted to learn deeper features and perform pre-classification. To reduce the number of parameters, the global average pooling layer is used instead of the fully connected layers. To further improve the recognition accuracy, the additive angular margin named arcface is used to enhance the discriminative power of the model. Finally, the re-identification operation determines the final result by calculating the distances between the features. The accuracy of the proposed method for typical electrical anomaly recognition is beyond 99% and for unknown anomaly detection exceeds 86%. The experimental results demonstrate the effectiveness and the superior performance of the proposed method in terms of recognition accuracy, unknown anomalies detection and computational complexity, compared to the NN, 2-D CNN, LSTM and CNN-LSTM.

Research on Ground-Airborne Frequency-Domain Electromagnetic Rapid Imaging Method Based on Space Magnetic Gradient Anomaly

Ground-airborne frequency-domain electromagnettic (GAFEM) is a method that has the potential to detect underground anomalies at large depth ranges in areas with complex terrain. Currently, for the demand of field real-time rapid interpretation of GAFEM data, the apparent resistivity method cannot effectively recognize anomaly boundaries, and divergence of tipper vector imaging method has difficulties in transmitting source deployment. In view of above problems, a rapid imaging method of GAFEM based on space magnetic gradient anomaly (MGA) is proposed. This method enables the rapid recognition of underground electrical anomalies by GAFEM data without large computational resources. First, the characteristics of the magnetic field gradients in the homogeneous half-space model and the 3D anomaly model are analyzed, and the calculation method of MGA based on the background field gradient is proposed. Further, the ability to recognize underground electrical anomalies in transverse MGA, longitudinal MGA, and space MGA are analyzed by a forward model. Finally, an imaging process that can be applied to actual detection and the calculation method of background resistivity are proposed. The feasibility, the anti-noise and the multi-anomaly recognition of the imaging method are verified. The results show the imaging method based on space MGA can effectively recognize the underground electrical anomalies. The magnitude of the space MGA can determine the location and contour of the anomaly, and the real and imaginary parts can determine the electrical type of the anomaly. This study provides a new method for the interpretation of GAFEM data, which is helpful for the rapid field real-time detection of underground structures.

Reconstruction of petrophysical zoning of the Blagodatnoye gold deposit in the Yenisei Ridge: Geodynamic and physical-chemical aspect

Research subject. Petrophysical zoning of the Blagodatnoye gold-sulfide deposit in the Yenisei Ridge. Aim. To determine indicative petrophysical characteristics of the products of the main occurrence stages and to develop an evolutionary petrophysical model of the investigated deposit.Materials and methods. Physical fields were studied by the methods of magnetic and electrical exploration and gamma-spectrometry. The petromagnetic heterogeneity and mineralogical-geo chemical features of formation of polymetamorphic complexes, metasomatites and ores were studied by a neutron activation analysis of the content of rare earth and radioactive elements, petrochemical x-ray fluorescence analysis, as well as by an electron-probe microanalysis of pyrite.Results. The syncollisional fold-overthrust fault (785 Ma) of the preparatory stage provided structural control over the ore-bearing mineral-forming system. The signs of zone dislocation metamorphism include geophysical anomalies: magnetic and natural electrical anomalies due to pyrrhotite and graphite mineralization of cleavage zones on fold limbs, and specific electrical resistance from silicification zones in fold hinges. The metasomatism of the pre-ore (753 Ma) and ore (698 Ma) stages took place under rifting conditions. Pre-ore quartz-muscovite and chlorite metasomatites with carbon mineralization and supra-background Au concentrations were formed under the action of reducing reaction solutions; they remained unaltered in the non-productive part of the deposit. These formations are characterized by elevated concentrations of radioactive elements and natural electrochemical polarizability. During the ore stage, Au was concentrated by fluids with hydro-carbonate-sulfide composition under the violation of the strike-slip kinematics, which caused significant petrophysical transformations of the productive part of the deposit. Early carbon metasomatites in the sub-ore and root sections of the ore bodies were depleted in terms of U, at the same time as retaining their electrochemical activity. Uranium accumulated in the upper horizons of the productive part, whose rocks lost their polarizability due to scattered carbonate mineralization. Magnetic pyrrhotite crystallized as part of sulfides with a regular increase in its proportion in the root sections of the ore bodies. At the final stage (368 Ma), the mineralized zone was broken into a series of blocks with unequal vertical displacements and levels of erosional truncation by upcasts. This led to the exposure of various-depth sections with contrast petrophysical characteristics.Conclusions. The Blagodatnoye deposit was formed in four stages: preparatory, two ore-generating and final. The petrophysical features of the products of each stage formed the basis for the developed evolutionary petrophysical model, which will be tested on the materials of geophysical studies of the Yenisei Ridge territories.

The Relationship Between Kimberlitic Magmatism and Electrical Conductivity Anomalies in the Mantle

AbstractKimberlites are igneous rocks whose formation remains enigmatic due to their severely altered nature, highly variable compositions and rapid ascent through the lithosphere. The spatiotemporal distribution of kimberlites suggests that mantle metasomatism may play an essential role in their emplacement. Since the magnetotelluric (MT) method is sensitive to metasomatic mantle modification in the forms of interconnected minerals and water, we compiled MT models from Australia, Brazil, Botswana, Canada, Namibia, South Africa and the USA, calculated water content variations and compared them to the distribution of kimberlites. Results indicate that kimberlites mostly ascend through hydrated/metasomatized lithosphere and avoid both dry and heavily metasomatized lithosphere. Diamondiferous kimberlites preferentially occur on moderately metasomatized lithosphere, with the diamondiferous rate increasing with the degree of metasomatism in Archean terranes and decreasing in Proterozoic terranes. These results link geophysical observations of mantle metasomatism to kimberlite magmatism and will improve mineral systems models for diamond exploration.