ABSTRACT Negative self‐potential anomalies can be generated at the ground surface by ore bodies and water contaminated with organic compounds. These are connected to distribution of redox potential water. To study relationship between anomalies, a controlled sandbox experiment was performed. We used metallic iron bar inserted in left‐hand side thin Plexiglas filled calibrated sand infiltrated an electrolyte. The signals were measured tank (at different time lapses) using pair non‐polarizing...

Natural self-potential (SP) fields observed in the vicinity of conductive orebodies can be explained terms electrochemical reactions which conductors participate. Battery-like models assume that a buried conductor creates an anode-cathode pair by conveying flow electrons to oxidizing areas shallow subsurface from reducing at depth. For with invariant composition (behaving as inert electrode), quantitative formulation is already available. Numerical Green’s functions are used allow one-step...

The equivalent layer calculation becomes more efficient by first converting the observed potential data set to a much smaller set, thus saving considerable CPU time. This makes equivalent‐source method of interpolation very competitive with other traditional gridding techniques that ignore fact anomalies are harmonic functions. is obtained using least‐squares iterative algorithm at each iteration solves an underdetermined system fitting all observations selected from previous iterations and...

We combine a stabilized reduction‐to‐the‐pole and an upward continuation filter to produce meaningful reduced‐to‐the‐pole fields at low magnetic latitudes. The stabilizing procedure is based on the development, in Taylor’s series, of theoretical expression for wavenumber domain. instability caused by huge amplitudes along magnetization azimuth, which are expressed infinite sum terms close unity. reduces simply truncating series. attenuates high component noise allows us design closer one....

We have developed an alternative formulation for Debye decomposition of complex electric conductivity spectra, by recasting it into a new set parameters with close relationship to the continuous method. The procedure determines relaxation time distribution (RTD) and two frequency-independent that modulate spectra. These represent (1) direct current contribution (2) range spanned low- high-frequency limits. times quantifies each distinct process. Assuming characteristic insignificant...

Interpolation using only the observations at discrete points is an ill‐posed problem because it admits infinite solutions. Usually, to reduce ambiguity, a priori information about sample function introduced. Current interpolation methods in mineral exploration introduce constraints of continuity and smoothness interpolating function. In potential‐field anomalies, constraint that sampled harmonic may be introduced by equivalent‐layer method (ELM). We compare performance ELM minimum curvature...

Here we combine the use of geo-electrical techniques with geochemical analysis solid and liquid phase to determine subsurface properties general peatland health. Active, degrading restored peat locations were analysed from same blanket bog site (ensuring they under environmental conditions, such as rainfall temperature) at Garron Plateau, Northern Ireland. A normalized chargeability (ratio resistivity (inverse conductivity) chargeability) profile was compared organic composition phases...

RESUMO O ensino de Ciências foi incorporado aos currículos escolares somente no século XIX. No Brasil-Império o das Naturais era incipiente, embora ciências já fizessem parte do currículo secundário desde a criação Colégio Pedro II, em 1837. Os primeiros cursos nível superior Geociências (Geologia, Geofísica, Meteorologia e Oceanografia) começaram ser criados partir da segunda metade passado. Atualmente, há nessas modalidades todo país, que enfrentam, contudo, sérios obstáculos para evolua...

Metallic structures are a common noise source in Slingram electromagnetic surveys because they interact with the primary magnetic field generated by transmitter coil and create secondary that distorts apparent conductivity readings from layered or homogeneous subsurface. The main challenge is understanding how their influence varies depending on loop configuration distance at which surface structure no longer readings. We propose methodology integrates experimental techniques numerical...

The Poisson theorem establishes a linear relationship between the gravity and magnetic potentials arising from common dense magnetized bodies with constant magnetization–density ratio magnetization direction. For geological formations satisfying such constraints (i.e., conditions), this provides suitable relationships anomalies that are useful in interpreting related data sets. In applications, both (MDR) direction can be estimated, thus helping subsurface mapping potential field acquired on...

Streaming potentials can be generated when geologic porous media are subjected to pumping tests. For a homogeneous medium, theory predicts that input and output points for water circulation generate field responses in the form of electric equivalent those produced by current sources externally driven power source. We evaluated tank experiments showing this assumption is valid common geophysical scenarios used determine charge density media, key parameter interpreting electrokinetic...

According to the Poisson theorem, gravity and magnetic fields arising from geologic bodies that share common sources, with a uniform magnetization-to-density ratio (MDR) magnetization direction, are related by linear transformation allows each field be calculated other. Provided these conditions on sources met, when data available over an area, theorem can used infer MDRs directions of their associated anomalies. These partially met in many structures but expected iron ore deposits, usually...

This paper presents a method to map the basement relief of homogeneous sedimentary basins that does not require knowledge basin density contrast. To reach this task, proposed relies on invariance inclination anomalous gravity field with contrast caused by models constituted two media. occurs because appears as constant factor in both vertical and horizontal components, therefore being canceled out when these components are divided during evaluation inclination. For such media, is independent...

Low-field mass-specific magnetic susceptibility (MS) measurements using multifrequency alternating fields are commonly used to evaluate concentration of ferrimagnetic particles in the transition superparamagnetic (SP) stable single domain (SSD). In classical palaeomagnetic analyses, this measurement serves as a preliminary assessment rock samples providing rapid, non-destructive, economical and easy information properties. The SP–SSD is relevant environmental studies because it has been...

The Tikhonov regularization parameter is a key controlling the smoothness degree and oscillations of regularized unknown solution. Usual methods to determine proper (L-curve or discrepancy principle, for example) are not readily applicable evaluation derivatives, since this formulation does make explicit set model parameters that necessary implement these methods. We develop procedure determination based on graphical construction characteristic "staircase" function associated with L2-norm...

Ultrafine grains of magnetic minerals provide reliable recordings both naturally occurring and anthropogenically generated particulate matter in polluted air; data can be used to understand biogenic iron-cycling anaerobic environments, as well pedogenesis palaeoclimate studies loess soils. The ultrafine fraction is produced under specific conditions easily recognized by its superparamagnetic (SP) behaviour. Many proxies have been proposed account for the SP contribution measuring...

Geophysical well logging has been applied for fracture characterization in crystalline terrains by physical properties measurements and borehole wall imaging. Some of these methods can be to monitor pumping tests identify fractures contributing groundwater flow and, with this, determine hydraulic conductivity transmissivity along the well. We present a procedure using spontaneous potential generated electrokinetic processes when water head is lowered then monitored while recovering. The...

The accumulation of biogenic greenhouse gases (methane, carbon dioxide) in organic sediments is an important factor the redevelopment and risk management many brownfield sites. Good practice with site characterization requires identification free-gas phases pathways that allow its migration release at ground surface. Gas pockets trapped subsurface have contrasting properties surrounding porous media favor their detection using geophysical methods. We developed a case study which gas were...

This paper shows an alternative way to obtain topography of the multidimensional objective function. strategy is based on dispersion analysis results obtained from multiple runs a stochastic optimization algorithm. The inverted parameters are represented in two-dimensional maps, but it does not mean that other model were kept fixed. Analyzing solution map format easy differentiate overall ambiguity local minima. We called this approach as Residual Function Dispersion Map (RFDM). Near-surface...