Magnetic Susceptibility Parameters Research Articles

The Effect of Chemical Fertilizers on The Magnetic Susceptibility Value and Soil Fertility of Paddy Soils in Surantih, Kabupaten Pesisir Selatan

Pesisir Selatan is a district where population depends on agriculture such as lowland rice. The rice seeds used were IR66. Efforts to improve the quality of Paddy soils seeds are fertilizing with chemical fertilizers. Chemical fertilizers used are Urea, KCL and Phonska. Continuous and excessive use of fertilizers will cause a decrease in the level of soil fertility due to the reaction between fertilizer minerals and soil minerals which also affects the magnetic susceptibility value. Based on these problems, further research was carried out to see the difference in the magnetic susceptibility value of paddy soils to the use of chemical fertilizers using the rock magnetism method with magnetic susceptibility parameters. The results showed that the paddy soil before and after being planted with rice seeds using chemical fertilizers decreased and increased the value of magnetic susceptibility due to the reaction between mineral fertilizers and soil minerals and waterlogging during the cultivation process. Meanwhile, the paddy soil before and after planting rice seeds that did not use chemical fertilizers decreased the magnetic susceptibility value quite far due to the absence of other mineral additions in the paddy soil such as chemical fertilizers.

Magnetic Susceptibility of Pumice at Mount Singgalang, West Sumatera

Volcanic activity produces eruptions that release pyroclastic material at the time of the explosion. Mount Singgalang is a volcano that has experienced an eruption after 1600. Several types of volcanic rocks around the Mount Singgalang area are Basalt, Andesite, Tuff Breccia, Lava Breccia, and Pumice Tuff. Pumice is formed when saturated liquid magma gas bursts like a carbonated beverage and soon cools, causing the froth that results to solidify into a glass full of gas bubbles. Some minerals contained in pumice are obsidian, cristobalite, feldspar, and tridymite. Pumice contains magnetic minerals, namely ilmenite (FeTiO3), and magnetite (Fe3O4). The purpose of this study is to quantify the magnetic susceptibility and quantity of pumice on Mount Singgalang in West Sumatera. When utilizing the Bartington Magnetic Susceptibility Meter to analyze a sample, magnetic susceptibility parameters are utilized to pinpoint the features of a magnetic rock mineral. The value of the magnetic susceptibility of pumice on Mount Singgalang, in West Sumatera has a value that varies between 2763.3 x 10-8m3/kg - 2192.1 x 10-8m3/kg. The results showed that the tested samples had antiferromagnetic magnetic mineral properties with frequency-dependent susceptibility values (χfd), indicating that all of the measured samples contained almost no superparamagnetic (SP) grains and were generally dominated by multi-domain (MD) grains.

Prediction of the soil properties of Malagasy rice soils based on the soil color and magnetic susceptibility

ABSTRACT Accurate assessments of soil properties are required to improve fertilizer management practices for crop production. Conventional chemical analysis in the laboratory is costly and time-consuming. Soil color is related to different soil compositions, while soil magnetic susceptibility (MS) has been found to reflect the abundance of magnetic minerals relevant to soil properties. Improving proximal sensing techniques for the analysis of soil color and MS provides opportunities for affordable and rapid assessments of soil properties. The aim of this study was to evaluate the potential use of soil color parameters and MS values to predict soil properties using stepwise multiple linear regression (SMLR), random forest (RF), and nonlinear regression approaches in lowland and upland fields in the central highlands of Madagascar. The target properties included the contents of soil organic carbon (SOC), total nitrogen (TN), oxalate-extractable phosphorus and iron (Feox), and the soil texture. The model prediction accuracy was assessed using the coefficient of determination (R2), root-mean-square error (RMSE), and the ratio of performance to interquartile distance (RPIQ). The use of soil color parameters yielded an acceptable prediction accuracy of the Feox content (loge Feox) for all rice fields (R2 = 0.54, RMSE = 0.55, RPIQ = 1.70) using the RF algorithm, while the SMLR approach gave the most accurate prediction for upland fields with acceptable reliabilities for SOC, Feox, and clay and sand content prediction, with R2 ranging from 0.43 to 0.67 and RPIQ from 1.63 to 1.77. In lowland fields, TN content was predicted with acceptable accuracy (R2 = 0.34, RMSE = 0.49, RPIQ = 1.71) using SMLR with the color parameter. The combination of the soil color parameters with the MS value as predictor variables increased SOC prediction for lowland fields using the RF approach (R2 = 0.57, RMSE = 6.37, RPIQ = 1.96). Use of the soil color and MS parameters was revealed to be a promising way to simplify the assessment of soil properties in upland and lowland ecosystems by using RF and SMLR approaches. A combined use of the soil color and MS parameters improved the prediction accuracy for the SOC content.

Combined Application of Quantitative Susceptibility Mapping and Diffusion Kurtosis Imaging Techniques to Investigate the Effect of Iron Deposition on Microstructural Changes in the Brain in Parkinson's Disease.

ObjectivesBrain iron deposition and microstructural changes in brain tissue are associated with Parkinson’s disease (PD). However, the correlation between these factors in Parkinson’s disease has been little studied. This study aimed to use quantitative susceptibility mapping combined with diffusion kurtosis imaging to investigate the effects of iron deposition on microstructural tissue alterations in the brain.MethodsQuantitative susceptibility mapping and diffusion kurtosis imaging were performed on 24 patients with early PD, 13 patients with advanced PD, and 25 healthy controls. The mean values of magnetic susceptibility and diffusion kurtosis were calculated for the bilateral substantia nigra, red nucleus, putamen, globus pallidus, and caudate nucleus, and compared between the groups. Correlation analyses between the diffusion kurtosis of each nucleus and its magnetic susceptibility parameters in PD patients and healthy controls were performed.ResultsThe study found a significant increase in iron deposition in the substantia nigra, red nucleus, putamen and globus pallidus, bilaterally, in patients with PD. Mean kurtosis values were increased in the substantia nigra but decreased in the globus pallidus; axial kurtosis values were decreased in both the substantia nigra and red nucleus; radial kurtosis values were increased in the substantia nigra but showed an opposite trend in the globus pallidus and caudate nucleus. In the substantia nigra of patients with PD, magnetic susceptibility was positively correlated with mean and radial kurtosis values, and negatively correlated with axial kurtosis. None of these correlations were significantly different in the control group. In the putamen, magnetic susceptibility was positively correlated with mean, axial, and radial kurtosis only in patients with advanced-stage PD.ConclusionOur study provides new evidence for brain iron content and microstructural alterations in patients with PD. Iron deposition may be a common mechanism for microstructural alterations in the substantia nigra and putamen of patients with PD. Tracking the dynamic changes in iron content and microstructure throughout the course of PD will help us to better understand the dynamics of iron metabolism and microstructural alterations in the pathogenesis of PD and to develop new approaches to monitor and treat PD.

A review of the magnetic susceptibility of guano deposits in caves

The study of environmental magnetic methods using magnetic susceptibility parameters in cave guano deposits has not been widely discussed, especially in Indonesia. This method is relatively inexpensive, fast, affordable, and non-destructive. Environmental magnetism is associated with environmental changes such as climate change and anthropogenic effects. After a brief introduction to the fundamental of environmental magnetism, we describe several case studies regarding the properties of magnetic minerals and magnetic grains. This study was complemented with XRF results to identify the elemental composition.

Magnetic susceptibility in the European Loess Belt: New and existing models of magnetic enhancement in loess

Magnetic susceptibility measurements play a key role in Quaternary studies. Magnetic proxies, such as low field and frequency-dependent magnetic susceptibility, are widely applied in the reconstruction of terrestrial paleoclimate, e.g., in the study of loess-paleosol successions. In general, the interpretation of loess magnetic susceptibility signals is based on two commonly accepted models: the pedogenic magnetic enhancement and wind-vigour models. However, there are an increasing number of cases where such models cannot be used. These cases show unusual relationships between the two common loess magnetic susceptibility proxies: low field and frequency-dependent magnetic susceptibility. Such relationships have been attributed to various phenomena including the dissolution of fine-grain minerals and the formation of ultrafine magnetic rims on the surface of coarser grains by weathering. Despite the growing number of these exceptional cases of magnetic enhancement, our knowledge about the occurrence and potential causes of the unusual behaviour of magnetic susceptibility parameters is still limited. This, in turn, hinders the wider application of magnetic susceptibility parameters in loess. To fill this knowledge gap, magnetic susceptibility data of various profiles from the European Loess Belt were collected and compared to reveal various enhancement trends in loess. Along with the analysis of magnetic susceptibility parameters, combined scanning electron microscopy (SEM) and rock magnetic analyses were applied to samples from the Paks loess sequence in Hungary to describe some of the irregular cases, notably the cause of increasing frequency-dependent susceptibility in non-altered sediments. Analysis of loess, paleosol and common mineral samples separated from loess (e.g., muscovite) revealed that various features may be responsible for these increasing frequency-dependent susceptibility values: i) surface weathering (maghemitization) of coarser detrital grains, ii) nanofragmentation by physical weathering and iii) the appearance of significant amounts of ultrafine magnetic inclusions in micas. These special modes of magnetic enhancement of loess do not undermine the importance of the basic theories suggested above, but rather provide three mechanisms that account for some of the increasing number of unusual cases. To aid in the wider and more accurate use of magnetic susceptibility parameters in loess, we review the current magnetic enhancement models with special emphasis on the identification of unusual trends in magnetic enhancement and understanding their drivers.

Penetrative Brinkman ferroconvection via internal heating in high porosity anisotropic porous layer: influence of boundaries

The penetrative ferrothermal convection (FTC) in a ferrofluid (FF) saturated high porosity anisotropic porous layer via uniform internal heating is investigated. The Brinkman-extended Darcy equation is applied to describe the flow in the porous medium. The permeability in the vertical direction is taken to be twice that of the permeability in the horizontal direction while the ratio of horizontal to vertical effective thermal diffusivity is allowed to vary. The Galerkin method is applied to solve numerically the stability eigenvalue problem for different boundary combinations namely, (i) rigid-paramagnetic (R–P) with large and low magnetic susceptibility, (ii) rigid-ferromagnetic (R–F), and (iii) free-ferromagnetic (F–F). The R–P boundaries with large magnetic susceptibility offer most, while F–F boundaries offer least stabilizing effect against FTC. Besides, the effect of increasing the magnetic number, non-linearity of fluid magnetization parameter, Darcy number and internal heat source strength is to speed up FTC, while the thermal anisotropy and magnetic susceptibility parameter indict a contradictory effect on FTC.

Three-dimensional model of magnetic susceptibility in forest topsoil: An indirect method to discriminate contaminant migration.

Soil magnetic susceptibility (MS) is an important parameter in pollution studies owing to its relationship with atmospheric deposition, and the concomitance of technogenic magnetic particles (TMPs) with potentially toxic elements (PTEs), Fe and Mn. In this study, we performed a detailed soil study under tree canopies for a forest area with high historical TMP-bearing industrial dust deposition. The technogenic sources of magnetic signals in topsoil were analyzed via scanning electron microscope electron dispersive spectroscopy (SEM/EDS), while the minor role of geogenic sources was obtained from soil profile analysis. To our knowledge, this is the first study to show soil TMP distribution in three dimensional (3D) space. In addition, using the data from 275 soil cores and 8250 individual measurements, 3D maps of MS for four tree species were plotted. There is a noticeable difference between coniferous (spruce and pine) and deciduous (beech and oak) species regarding depth of maximum concentration of magnetic particles in the topsoil. For beech and oak, maximum MS values were measured at 3cm depth; pine and spruce, maximum MS values were measured at 5cm depth. However, no significant differences were found among tree species in terms of mean MS or PTE contents. This suggests that there is little different among tree species in terms of dust capture over their life span. Significant correlations between MS and other parameters (PTEs and organic matter contents) present new possibilities for spatial 3D analysis of topsoil horizons.

Analysis of Ultramafic Rocks Weathering Level in Konawe Regency, Southeast Sulawesi, Indonesia Using the Magnetic Susceptibility Parameter

The Konawe region is part of the Sulawesi Southeast Arm ophiolite belt where ultramafic rocks are exposed in the form of dunite and peridotite. The formation of nickel deposits is closely related to the weathering process of ultramafic rocks as a source rock. Ultramafic rocks exposed to the surface will experience weathering which is influenced by many factors, including in the form of climate change, topography, and existing geological structures.
 The weathering process in the source rock can influence variations in chemical elements and magnetic properties in laterite soil profiles. For example, the chemical weathering might affect magnetic mineralogy and the physical weathering could affect granulometry as well as the quantity of magnetic minerals in the soil. Condition of weathering of ultramafic rocks (initial, moderate and advanced) can affect nickel content in laterite sediments. The weathering profile study of serpentine mineral is an indication of the lateralization process that occurs in ultramafic rocks and is carried out through petrographic analysis of thin cuts and polish cuts. Determination of weathering level like this is based on the level of weathering of the mineral serpentine.
 In this study, the determination of the weathering level of ultramafic rocks (initial, moderate, and continued) uses magnetic susceptibility parameter. A total of 232 ultramafic rock core samples obtained from 34 hand samples were taken from different places and weathered levels were analyzed. The results of the research have shown that the magnetic susceptibility of ultramafic rocks in the study area varies, from 580 x 10-6 SI to 4.724 x 10-6 SI. Based on the value of magnetic susceptibility, magnetic minerals contained in ultramafic rock samples are hematite and geotite minerals. This means that the weathering level of ultramafic rock samples is the continued weathering level. The level of continued weathering that occurs in ultramafic rocks in the study area produces nickel laterite deposits with a nickel content of 1.65 - 2.40% in the saprolite zone, 0.42% in the saprock zone, and 0.20 - 0.51% in the basic rock zone (bedrock).

Magnetic susceptibility parameters as proxies for desert sediment provenance

Magnetic susceptibility in sediments has been thoroughly studied as a paleoenvironmental proxy over the last decades. However, it is unknown to what extent magnetic susceptibility variation is also a diagnostic of different sediment sources. Here we investigate if multiple magnetic susceptibility-based parameters can effectively be used as sediment source indicators. New magnetic property data from the Mu Us and Tengger Deserts in China are compared to previously known sediment provenance based on other well-established proxies. To assess the magnetic properties of these deserts, magnetic susceptibility and its out-of-phase component, its dependence on frequency, temperature and low-field amplitude are analyzed. Our results indicate similar sources for the western Mu Us Desert and the Tengger Desert and a distinct source for the eastern Mu Us, in-line with previously hypothesized provenance patterns. However, magnetic properties within the Tengger Desert sediments are homogenous, which may suggest a uniform provenance for the entire Tengger Desert, that the sediments are greatly reworked, or similar magnetic properties in potential multiple source regions. Magnetite is the major magnetic mineral in the study area and the dominant causes for divergence in magnetic properties are the magnetic mineral concentration and domain state. The results here, in particular from the Mu Us, suggest considerable promise for using magnetic susceptibility parameters in desert sediment provenance research.

Crystal Mush Flow in Small Concentrically Expanded Pluton (Castle Crags Pluton; Klamath Mountains, CA, USA)

AbstractUnderstanding of the processes of magmatic fabric formation in crystal‐rich magmas and their reflection in rock magnetic properties are important for understanding pluton formation and intrusion mechanisms. On the example of small concentrically zoned Castle Crags pluton in the Klamath Mountains (CA, USA) we provide reconstruction of the flow/deformation mechanisms of the crystal‐rich magma and pluton growth based on detailed structural mapping and microstructural analysis employing the anisotropy of magnetic susceptibility, microstructural analysis, and crystallographic preferred orientation. Our study reveal microstructural evidence for progressive development of magmatic textures in the pluton core transitioning to submagmatic and eventually subsolidus fabric at the pluton periphery, that is interpreted in terms of the flow/deformation of the crystal mush. The documented magmatic textures are linked to anisotropy of magnetic susceptibility parameters and orientation. The recorded anomalous degree of anisotropy of magnetic susceptibility found in the pluton is attributed to tiling and plastic deformation of magnetite grains by the surrounding phenocrysts. The concentric structure of the pluton resulted from horizontal compaction and margin parallel stretching of the dense crystal mush around the vertically intruding trondhjemite magma in the pluton core. The Castle Crags pluton is interpreted as a concentrically expanded pluton, which grew at least by two increments of granodiorite and trondhjemite magma emplacement.

Application of Magnetic Susceptibility Parameters in Research of Igneous Rock in Chepaizi

The Carboniferous reservoir of the Chepaizi High in the Junggar Basin is mainly composed of igneous rocks, with complex lithology and low exploration degree. The reservoir is highly heterogeneous and the development characteristics are not clear. The heterogeneity of the Carboniferous reservoir was studied by using the magnetic susceptibility measured in the field or by coring as well as the logging data, thereby, the reservoir space, physical characteristics, distribution characteristics and lithofacies development characteristics and hydrocarbon content of the Carboniferous igneous reservoir were analyzed. The results show that the Carboniferous rocks with high magnetic susceptibility are prone to be weathered into a favorable reservoir with good physical properties, while the Carboniferous rocks with low magnetic susceptibility are difficult to develop into a favorable reservoir, and only occurs near the fault zone. This provides an important basis for the exploration of igneous oil and gas in the study area.

Computation of Magnetic Field Distortions and Impact on T2*-weighted MRI, with Applications to Magnetic Susceptibility Parameter Estimation

A two-step numerical computation of T2* signal weighting maps in gradient echo magnetic resonance imaging in the presence of an object with varied susceptibility property is presented. In the first step, the magnetic scalar potential is computed for an arbitrary 2D magnetic susceptibility distribution using an algebraic solver. The corresponding magnetic field disturbance is computed from the magnetic scalar potential. In the second step, nonlinear operations are used to compute T2* from the magnetic field disturbance and then to generate a map of T2* signal weighting. The linearity of the first step of the solution process is used to implement a superposition of basis solutions approach that increases computational efficiency. Superposition of basis solutions, computed from a system composed of a single node of differing magnetic susceptibility from the surround, herein referred to as the base system, is found to provide an accurate estimation of the scalar potential for arbitrary susceptibility distributions. Afterwards, nonlinear computation of the T2* signal weighting maps can be performed. The properties of the algebraic magnetic scalar potential solver are discussed in this work. Finally, the linearity of the magnetic scalar potential solver is used to estimate the magnetic susceptibility of various objects from in vitro MR-imaging data acquired at 9.4 T.

Magnetic susceptibility characteristics of surface soils in the Xilingele grassland and their implication for soil redistribution in wind-dominated landscapes: A preliminary study

Wind erosion processes in the typical temperate Xilingele grassland of North China result in significant regional surface soil fine particle and carbon loss. They increasingly restrict local grass industry sustainable production and grassland ecosystem protection. It is challenging to link wind erosion and deposition at landscape scale using classical field monitoring or the expensive fallout environmental radionuclides tracing techniques. The low-cost but efficient magnetic susceptibility (MS) technique has been successfully demonstrated to have great potential to trace soil water erosion processes and patterns at large spatial and temporal scales. However, so far soil wind erosion research using MS technique has not been reported. This study had a trial to determine the variations of soil magnetic susceptibility on relative flat grassland by a grid soil sampling and to establish the relationship between wind erosion parameters and variations of MS in surface soils. 160 grid sampling sites were spaced at an interval of 400m across a study transect with 12.8km long and 1.6km wide. 319 soil samples were collected from the surface soils (0–1cm and 1–6cm layers). Grazing intensity of the sampling sites were investigated, and the samples were measured for mass-specific low-frequency magnetic susceptibility (χlf), absolute frequency-dependent magnetic susceptibility (χfd), percentage frequency-dependent magnetic susceptibility (χfd%), soil grain size and organic carbon concentrations. The results showed that the χlf, χfd and χfd% values in surface soils ranged from 30.0 to 97.8×10−8m3kg−1, 1.2 to 6.1×10−8m3kg−1 and from 3.2 to 8.0%, respectively. The variations of soil χlf values were closely related to grazing intensity, soil grain size and organic carbon concentrations, suggesting that soil erosion processes were very sensitive to soil properties. Moreover, the MS parameters (χlf, χfd%) were positively correlated with the soil erosion rates and negatively correlated with the dust deposition rates, indicating that MS parameters could potentially identify the erosion and dust deposition stages of wind dominated erosion processes in semi-arid grassland, respectively. These preliminary experimental results implied that magnetic susceptibility signals in surface soils will hopefully serve as a useful tool in the accuracy assessment of wind dominated erosion and deposition in the temperate grassland regions.

Estudio petrográfico, espectral y de susceptibilidad magnética de la alteración hidrotermal asociada con depósitos polimetálicos de Pb-Zn-Cu-Ag-Au, Sierra de Comechingones, Córdoba (Argentina)

En el basamento metamórfico de la Sierra de Comechingones, extensión más austral de las Sierras de Córdoba (Argentina), se emplaza un conjunto de vetas polimetálicas con Pb, Zn, Cu, Ag, Au asociadas con zonas de alteración hidrotermal, que constituyen el registro de una época metalogenética ocurrida hacia fines del Paleozoico. En este trabajo la aplicación de técnicas espectrales en la región del SWIR (infrarrojo de onda corta) y magnéticas, poco usual en Argentina para este estilo de mineralización, demostró ser una herramienta eficaz en el estudio de las zonas alteradas y de utilidad para establecer targets de prospección y/o exploración. La asociación sericita-cuarzo es el principal producto de alteración hidrotermal de las rocas de caja migmáticas, se desarrolla en franjas estrechas pero continuas que siguen el rumbo principal de las estructuras mineralizadas y pueden alcanzar hasta 5 metros de potencia hacia los laterales. En sectores localizados, una asociación carbonática de siderita-calcita se desarrolla como consecuencia de la alteración de anfibolitas intercaladas dentro de la secuencia metamórfica. En los espectros de reflectancia, la posición del rasgo de absorción Al-OH indicó una variación composicional y procesos de sustitución iónica en las micas blancas de origen hidrotermal, desde micas potásicas (longitudes de onda cercanas a 2200 nm) a micas con menor contenido relativo de Al en el sitio octaédrico (longitudes de onda > a 2210 nm) tendientes a la variedad fengita. Estas variaciones y su distribución espacial están controladas fundamentalmente por tres factores: 1) temperatura del fluido hidrotermal, 2) pH y/o 3) relación Mg-Fe/Al dentro del sistema fluido-roca. Los índices de cristalinidad (IC) calculados a partir de los datos espectrales revelaron la predominancia de illitas de alta cristalinidad con un leve incremento de este parámetro hacia las zonas proximales a las vetas mineralizadas. Las interestratificaciones de illita/esmectita hacia las zonas distales de algunas estructuras, reflejan la disminución de la temperatura del fluido y pueden ser utilizadas como vectores hacia las mineralizaciones. Las asociaciones hidrotermales sericita-cuarzo y siderita-calcita están frecuentemente afectadas por los procesos de oxidación supergénica que condujeron a una conspicua precipitación de hematita-goethita dentro de las zonas alteradas. El estado de oxidación del Fe+3 en estos minerales es la principal causa de la disminución del parámetro de susceptibilidad magnética de las rocas hospedantes. Desde una perspectiva regional, estas zonas de alteración hidrotermal caracterizadas por una alta abundancia de micas blancas de moderada a alta cristalinidad (IC=1,21-3,92 e IK=0,21-0,23), composiciones variables entre potásicas y fengíticas (absorción del enlace Al-OH entre 2200 y 2215 nm) y asociadas con zonas de hematización y bajos valores de susceptibilidad magnética (< 0,2 x 10-3SI), pueden considerase como potenciales targets para futuras etapas de prospección y/o exploración de vetas polimetálicas emplazadas en el ambiente metamórfico de las Sierras Pampeanas.

Susceptibility tensor imaging (STI) of the brain.

Susceptibility tensor imaging (STI) is a recently developed MRI technique that allows quantitative determination of orientation-independent magnetic susceptibility parameters from the dependence of gradient echo signal phase on the orientation of biological tissues with respect to the main magnetic field. By modeling the magnetic susceptibility of each voxel as a symmetric rank-2 tensor, individual magnetic susceptibility tensor elements as well as the mean magnetic susceptibility and magnetic susceptibility anisotropy can be determined for brain tissues that would still show orientation dependence after conventional scalar-based quantitative susceptibility mapping to remove such dependence. Similar to diffusion tensor imaging, STI allows mapping of brain white matter fiber orientations and reconstruction of 3D white matter pathways using the principal eigenvectors of the susceptibility tensor. In contrast to diffusion anisotropy, the main determinant factor of the susceptibility anisotropy in brain white matter is myelin. Another unique feature of the susceptibility anisotropy of white matter is its sensitivity to gadolinium-based contrast agents. Mechanistically, MRI-observed susceptibility anisotropy is mainly attributed to the highly ordered lipid molecules in the myelin sheath. STI provides a consistent interpretation of the dependence of phase and susceptibility on orientation at multiple scales. This article reviews the key experimental findings and physical theories that led to the development of STI, its practical implementations, and its applications for brain research. Copyright © 2016 John Wiley & Sons, Ltd.

Impact of Long-Term Irrigation with Treated Sewage on Soil Magnetic Susceptibility and Organic Matter Content in North China.

This study assessed the effect on magnetic susceptibility and organic matter content of arable soil by irrigation with either treated sewage or groundwater. Results indicated that organic matter and magnetic susceptibility values in the soil irrigated with sewage were increased by 7.1 % and 13.5 %, respectively, compared to agricultural soil that irrigated with groundwater. Both the sewage and groundwater irrigated soils contained a significant fraction of ultrafine superpara magnetic grains, as indicated by high frequency dependent susceptibility (χfd > 6 %). The enhancement of soil magnetic properties was determined to be caused by anthropogenic sewage irrigation and agrochemical use by investigation of vertical soil profiles. Magnetic susceptibility parameters were shown to be significantly correlated with organic matter content (y = 0.0057x + 1.3439, R(2) = 0.09, p < 0.05). This work indicates that measurements of magnetic susceptibility may offer a rapid first step for identifying the potential pollution in arable soils.

Forceful emplacement of the Eureka Valley–Joshua Flat–Beer Creek composite pluton into a structural basin in eastern California; internal structure and wall rock deformation

Abstract Anisotropy of Magnetic Susceptibility parameters have been analyzed at 311 locations in the Eureka Valley–Joshua Flat–Beer Creek (EJB) pluton of eastern California. The large amount of data has allowed for the AMS parameters to be contoured using techniques that both reveal map-scale trends and emphasize small-scale differences. The contour maps suggest that magnetic susceptibility is dominantly controlled by composition of the magma but may also be affected by emplacement-related strain as the magma chamber inflated and forced the wall rocks outward. Pluton construction involved two major pulses of different composition magmas that were emplaced sequentially but with overlapping periods of crystallization. The magmas initially intruded as sill-like bodies into a structural basin. The magnetic foliation of the pluton cuts across internal magmatic contacts on the map scale and is parallel to local contacts between the pluton and surrounding metasedimentary wall rocks. The magnetic fabric is similar in orientation and symmetry to intense flattening strains recorded in the aureole rocks. The metasedimentary wall rocks have been shortened between 60 and 70% and this strain magnitude is approximately equal on the west, south, and east margins of the pluton. Strain in the wall rocks is dominantly flattening and concentrated into a narrow (1 km wide) inner aureole. Mapping of bedding/cleavage intersection lineations south of the pluton indicates that the magma made room for itself by translating the wall rocks outward and rotating the already inward dipping wall rocks of the structural basin to sub-vertical. Stretching of the inner aureole around an expanding magma chamber was responsible for the intense shortening. Limited data on the Marble Canyon pluton to the south of the EJB pluton indicates a very similar emplacement process.

Changing environmental conditions in recent past — Reading through the study of geochemical characteristics, magnetic parameters and sedimentation rate of mudflats, central west coast of India

Geochemical (sediment components, major and trace metals), magnetic related parameters (concentration, mineralogy and grain size) and radionuclide (210Pb) analyses were carried out on sediment cores collected from mudflat regions of central west coast of India viz, Kolamb creek (Malvan), Mandovi estuary (Panaji) and Tadri creek (Gokarn), in order to study the variations in sediment characteristics with time. The changes in spatial and temporal (depth) distributions of sediment composition were observed to be mainly controlled by the catchment area geology, geomorphology and anthropogenic activities. The sedimentation rate in the study area varied from 0.13 to 2cm/yr. The rate was extremely low at the lower half of the cores (0.13–0.31cm/yr, before ~1980) as compared to the near surface (1.21–2cm/yr, after ~1980) with two clear phases of sedimentation rates. The higher sedimentation rate in the upper portions of the cores was found to correspond to increased deposition of finer sediment components, metals and magnetic minerals which in turn were found to be mainly controlled by geology and/or human activities. The results of the present study reveal variations in sediment properties with time and support the use of geochemical in addition to magnetic susceptibility parameters on mudflats to understand changing environmental conditions of recent past.

Crustal and Mantle Structure of the Bohai Bay Area Based on Gravity and Magnetic Data

AbstractBohai bay basin is the center area of the destruction of North China Craton (NCC). The deep structure study of the Bohai Sea plays a key role in understanding the scope and dynamic process of the destruction of NCC. In this paper, we studied the crustal structure of the profile from Xincheng, Jinghai, to Bohai Sea along the southeast direction based on the gravity and magnetic data. The initial model was build based on the former studies about the sedimentary structure, deep crustal structure and the onshore‐offshore seismic survey in 2010. Combined with the density and magnetic susceptibility parameters in this area, the crustal structure and the physical parameter distribution were determined using 2.5D gravity and magnetic inversion method. The integrated study indicates that the Moho becomes shallower from the land to the sea. The Moho of the Bohai Sea is shallower, and has a local uplift in Shaleitian area with about 2 km uplift. The variation of the Moho is similar with the lithosphere thinning in the eastern NCC. It reflects that lithosphere and deep crustal structure were similarly affected by the destruction of the NCC from Mesozoic. We do the deep uplifting modeling to test the gravity effects from the mantle uplifting. Combined with the analysis of the gravity of the profile, it is less likely to have mantle plume or large mantle uplifting in the Bohai Sea, the local small uplifting of the Moho in Bohai Sea is likely related with a small anomaly body in the upper mantle.