Palaeomagnetic studies on some South African rocks

 

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dc.contributor.author Graham, Kenneth William Turner en_ZA
dc.date.accessioned 2016-10-21T07:35:53Z
dc.date.available 2016-10-21T07:35:53Z
dc.date.issued 1961 en_ZA
dc.identifier.citation Graham, K. 1961. Palaeomagnetic studies on some South African rocks. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/22239
dc.description.abstract A brief review of the subject of palaeomagnetism as it affects the study of the behaviour of the earth's magnetic field and the problems of Continental Drift and Polar wander is presented, giving the reasons why a systematic palaeomagnetic study of the Cape and Karroo Systems of South Africa would be of outstanding significance. This task was vigorously tackled by sampling the Karroo System at vertical intervals of approximately 50 ft. in two separate areas, using the techniques that were then available. The results, although negative, provide material for a discussion of the possible reasons for the scattered directions of magnetization of the samples. A palaeomagnetic study of the Karroo dolerites was undertaken in an attempt to (i) determine 1 the position of the geomagnetic pole at the time of the intrusions, and (ii) possibly assess the importance of the remagnetization of Karroo sediments by the thermal effects of the younger intrusions. Samples from surface exposures in the eastern half of South Africa, from the shafts of a gold mine and from a railway tunnel were collected and studied, giving a reliable mean direction of magnetization of the Karroo dolerites of Declination= 341°, Inclination= -60°. At the commencement of the Jurassic period the geomagnetic pole relative to Southern Africa had the present day co-ordinates of Longitude 74½ 0 E, Latitude 70° S. Both normally and reversely magnetized dolerites were found and evidence in favour of a true reversal of the earthts magnetic field is advanced. It is also suggested that in the area studied, the dolerite was intruded in two distinct phases. Because the direction of magnetization of the Karroo dolerites is very close to that of the present magnetic field, it is difficult to separate samples remagnetized at the time of the intrusions from those remagnetized in the present field. However, some light is thrown on the problem of the scattered directions of magnetization of the Karroo sediments by the fact that dolerite samples collected from surface exposures are much less consistently magnetized than those from underground workings. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Geological Sciences en_ZA
dc.subject.other Continental Drift en_ZA
dc.subject.other Polar wander en_ZA
dc.title Palaeomagnetic studies on some South African rocks en_ZA
dc.type Doctoral Thesis
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Science en_ZA
dc.publisher.department Department of Geological Sciences en_ZA
dc.type.qualificationlevel Doctoral
dc.type.qualificationname PhD en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Graham, K. W. T. (1961). <i>Palaeomagnetic studies on some South African rocks</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Geological Sciences. Retrieved from http://hdl.handle.net/11427/22239 en_ZA
dc.identifier.chicagocitation Graham, Kenneth William Turner. <i>"Palaeomagnetic studies on some South African rocks."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 1961. http://hdl.handle.net/11427/22239 en_ZA
dc.identifier.vancouvercitation Graham KWT. Palaeomagnetic studies on some South African rocks. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 1961 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/22239 en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Graham, Kenneth William Turner AB - A brief review of the subject of palaeomagnetism as it affects the study of the behaviour of the earth's magnetic field and the problems of Continental Drift and Polar wander is presented, giving the reasons why a systematic palaeomagnetic study of the Cape and Karroo Systems of South Africa would be of outstanding significance. This task was vigorously tackled by sampling the Karroo System at vertical intervals of approximately 50 ft. in two separate areas, using the techniques that were then available. The results, although negative, provide material for a discussion of the possible reasons for the scattered directions of magnetization of the samples. A palaeomagnetic study of the Karroo dolerites was undertaken in an attempt to (i) determine 1 the position of the geomagnetic pole at the time of the intrusions, and (ii) possibly assess the importance of the remagnetization of Karroo sediments by the thermal effects of the younger intrusions. Samples from surface exposures in the eastern half of South Africa, from the shafts of a gold mine and from a railway tunnel were collected and studied, giving a reliable mean direction of magnetization of the Karroo dolerites of Declination= 341°, Inclination= -60°. At the commencement of the Jurassic period the geomagnetic pole relative to Southern Africa had the present day co-ordinates of Longitude 74½ 0 E, Latitude 70° S. Both normally and reversely magnetized dolerites were found and evidence in favour of a true reversal of the earthts magnetic field is advanced. It is also suggested that in the area studied, the dolerite was intruded in two distinct phases. Because the direction of magnetization of the Karroo dolerites is very close to that of the present magnetic field, it is difficult to separate samples remagnetized at the time of the intrusions from those remagnetized in the present field. However, some light is thrown on the problem of the scattered directions of magnetization of the Karroo sediments by the fact that dolerite samples collected from surface exposures are much less consistently magnetized than those from underground workings. DA - 1961 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1961 T1 - Palaeomagnetic studies on some South African rocks TI - Palaeomagnetic studies on some South African rocks UR - http://hdl.handle.net/11427/22239 ER - en_ZA


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