Showing papers in "Geoexploration in 1976"

TL;DR: The resistivity method has proved to be very suitable in determining the distribution of fresh and saline groundwater in sedimentary deposits as occur in the Netherlands as discussed by the authors, however, the method gives no information about recharge, groundwater flow, geohydrological constants (permeability, transmissibility and hydraulic resistance) and the presence of relatively thin layers of bad hydraulic conductivity.

TL;DR: In this article, the magnetic and gravity anomalies of polygonal section prisms of finite length and general irregular polyhedra are calculated for any body of uniform magnetization or density.

TL;DR: In this article, the importance of a geological concept in collaborations between the geologist and the geophysicist to overcome the difficulties arising from the fundamental limits of the resistivity method is outlined.

TL;DR: In this article, an interpretation method for magnetic field data is developed, based on analytical expressions for the fields due to magnetized vertical rectangular prisms, and a least-squares iterative approach, using the Marquardt nonlinear optimization technique, is employed to fit a model to the observed anomaly data.

TL;DR: In this paper, the authors discuss the background to and development of a method for determining porosity (and hence indirectly, permeability) in British Triassic sandstones which is based on surface resistivity measurements supplemented by data from borehole cores.

TL;DR: In this article, the authors carried out experimental electromagnetic frequency sounding surveys in two arid areas in South Tunisia and used only horizontal transmitting coils because these allow a far greater strength of the transmitted field than vertical coils.

TL;DR: The cause of magnetic anomalies arising from archaeological sources together with established overseas field surveying and interpretation techniques are reviewed in this article, where a simple system is described which enables interpretation to be carried out on the site without the need for computing.

TL;DR: In this paper, a repeatable square matrix is developed for use with regularly sampled terrain elevations, where the terrain surface is approximated by square prisms with sloping upper surfaces.

TL;DR: Optimum linear operators designed according to the Wiener least-squares criteria can be applied to filter gravity and magnetic fields to produce direct mappings of interfaces and layer thicknesses as discussed by the authors.

TL;DR: In this paper, a simple linear regression analysis of velocity/porosity data for limestones from the Portland Group of southern England is presented, which is divided into four main petrographic types (sparsites, micrites, microsparites and chalks) on the basis of texture and grain size of cement.

TL;DR: In this article, the Laplace transform theory is applied to the correlation between frequency-domain and transient IP measurements, and a simple integral relation between the complex frequency-dependent resistivity and the time-dependent chargeability is at first obtained.

TL;DR: In this paper, resistivity sounding curves are examined as a site characteristic and the association parameter is defined as an objective assessment of site differences, and the use of an appropriate window of comparison to limit surface variations, and use of the L.I.I to screen uncharacteristic sounding results, are discussed.

TL;DR: In this article, it was shown that error magnification is the cause of the phenomenon known as equivalence and that the error magnification depends on the ratio of the coordinates of a point of the transform curve to the parameters of the layer that is being removed.

TL;DR: In this article, it is shown that two-dimensional magnetic interpretation is greatly simplified, if two components of the anomalous field are measured, making use of complex numbers, and it is possible to solve exactly the position and magnetization (two components) of cylinders and infinitely deep thin plates or the thickness and one position parameter of infinitely deep thick plates with known magnetization.

TL;DR: In this article, the main aspects of aquifers are examined from the view point of hydraulic engineering, aiming to point out which are the parameters related to the exploitation and protection of underground water resources.

TL;DR: In this paper, a set of curves is presented which is designed to aid the interpreter in the choice between a 2D or 3D approach to gravity interpretation, and the curves are used as an initial test to show that many apparently "3D" anomalies could be successfully treated in a "2D" manner if certain conditions are met.

TL;DR: In this paper, the Gauss-Seidel method is used to find approximate magnetization and density distributions by dividing the ground into bodies with homogeneous properties, and the resulting linear equation system for the material constants of the bodies are efficiently solved by the iterative Gauss Seidel method, which has theoretically simple convergence criteria and small requirements on computer capacity.

TL;DR: In this paper, the amplitude distribution pattern at various depths of a point scatterer is estimated using the magnitude of the projected complex amplitude, and an unbiased estimator of the true depth to the scatterers is formed, where the peak amplitude for the downward continued response shows an increase with depth up to true depth and then falls off rapidly.

TL;DR: Transient and harmonic field methods have been compared in this paper and a definite advantage of transient methods over harmonic methods in ore prospecting has been shown by taking a conductive sphere as an example.