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1st SAGA Biennial Conference and Exhibition
- Conference date: 29 Jun 1989 - 30 Jun 1989
- Location: Johannesburg, South Africa
- Published: 29 June 1989
41 - 49 of 49 results
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Geophysical Investigation Into The Entabeni And Palmietfontein Granites, And The Schiel Alkaline Complex In The Northern Transvaal And Venda
Authors E.H. Stettler, J.H. de Beer and R.J. KleywegtThe late Precambrian and early Protozoic was an important period in the history of the Kaapvaal Craton since it not only represents the final episode of the Limpopo metamorphic event at 2670 Ma (Van Reenen et al., 1988) but also the intrusion of large volumes of alkaline granite magmas, the so called “young granites” took place between 2650-2400 Ma, represented by the Turfloop, Da Maranda (± 2650 Ma); Moletsi, Lunsklip, Uitloop Shamiriri (± 2600 Ma); Smitskraal, Matlala (2500 Ma) and the youngest ones Palmietfontein (± 2456 Ma) and Entabeni (±2000 Barton pers. comm.) (Barton et al., 1983; Van Reenen et al., 1988).
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A Slide Show To Cultivate An Interest In Geophysics In School Children
Authors E.H. Stettler, J.C. Slee and A. du PlessisIn order to make school children more aware of geophysics as an
occupation a slide show was prepared on behalf of SAGA that consists
of humoristic cartoons and real life situations that explain geophysics as
a science and also as a rewarding career. The duration of the slide
sequence Is 20 minutes and is available in both official languages. The
approach of intermingling cartoons with slides depicting real
geophysics at work was chosen to keep the attention of children and to
counter the traditional negative view school children have about the
natural sciences (See SACN March 1989 first article).
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Comparison Of Seismic Acquisition Systems From Repeated Recording Experiments
By P.J. VailFor the last eight years SOEKOR bas conducted a repeated recording experiment on a test line over the FA structure on the eastern flank of the Bredasdorp basin in the southern offshore area of South Africa. The primary purpose of the project was to acquire data using different seismic sources and acquisition systems so that comparisons of these systems and of the quality of the final stacked seismic section could be made. Of particular interest was the comparison of data acquired with air guns and water guns. The project involves two phases. The initial phase, discussed in this presentation involves the comparison of different seismic sources. The second phase will involve the determination of the optimum processing parameters for each data set and a comparison of these parameters.
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Including Absorption Into The Convolutional Model Of The Seismic Trace
More LessHigher frequency seismic signals travel faster than lower frequency
signals. Thus it can be expected that some component of the differences
observed between velocities calculated from check shots (signal frequency
50 hz.) and sonic logs (signal frequency 12000-30000 Hz) would be due to
dispersive effects. In fact it has been stated (GSI 1983) that with modern
sonic tools most of this difference can be ascribed to dispersive
effects. Thus using a properly edited sonic log and calculating the
synthetic with accurate absorption should remove the need for check shot
calibration of the sonic log to obtain accurate ties to the seismic
section.
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The Magnetic Vertical Gradient: A Study To Quantify Filter Parameters
Authors P.A. Versnel and L.A.G. AntoineWith the advent of the Image Processor, large regional magnetic data sets are now routinely being processed. Linear and non-linear transformations are commonly applied to the data in order to enhance various aspects of the image. The magnetic vertical gradient is one such transformation. Although employed for many decades on potential field data, it bas in general been used in a qualitative sense. For example, in the form of a high-pass filter. The vertical gradient is not necessarily restricted to qualitative applications, many automated depth estimation techniques make use of the vertical gradient.
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Current Filament Modelling Of Transient Electromagnetic Data
More LessA PC based Transient Electromagnetic (TEM) data processing system based on Barnett current filament modelling has been developed at CSTR, to process profiling data.
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Tem Profiling In Conductive Environments - A Case Study On The Vlakfontein Shear Zone Near Pilanesberg
More LessHost TEM profiling interpretation techniques assume the host rock
response is negligible, i.e. the host rock is highly resistive
relative to the ore body under investigation, and may be
neglected at sufficiently late times. Sometimes it is assumed
that the host rock response approximates that of a homogeneous,
isotropic half-space or of a conductive overburden which may be
subtracted directly from the data (linear superposition). In
complex conductive environments such as shear zones these
assumptions may be invalid, and no existing interpretation
techniques will be successful.
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A Geophysical Investigation Of The Rodium Reefs Project
By E.E.W. WederGeophysics played an important role in the exploration of the
Rhodium Reefs Project. A detailed helicopter-borne survey was
conducted at 100 metres flight line spacing to delineate faults,
dykes and iron pegmatites. This information was crucial in
planning the drilling programme. The Kennedy’s Vale vanadiferous
magnetite plug was well delineated on the aeromagnetic map.
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Depth Imaging In The Karoo By Simple Processing Of Transient Electromagnetic Data
By M.W. ZangA UTEM (University of Toronto Electromagnetic) survey has been
carried Out in the Orange Free State to help define the pre-Karoo
basement topography and thus search for geologic structures that
may host a gas reservoir. This survey has been done by
collecting an 8 km line of vertical-component magnetic UTEM data
which have been processed by the Depth Image Processing, or DIP,
technique.
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