Palaeomagnetism of Late Palaeozoic and Early Mesozoic rocks of South America
Further geological evidence and radiometric studies of South American igneous rocks suggest, (i) a Middle Permian age for geomagnetic poles until now quoted as Permo-Triassic or Lower Triassic, and (ii) a Middle-Upper Triassic age for a geomagnetic pole previously quoted either as Middle or Upper Tr...
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1972
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| Online Access: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0012821X_v15_n1_p75_Valencio https://hdl.handle.net/20.500.12110/paper_0012821X_v15_n1_p75_Valencio |
| Summary: | Further geological evidence and radiometric studies of South American igneous rocks suggest, (i) a Middle Permian age for geomagnetic poles until now quoted as Permo-Triassic or Lower Triassic, and (ii) a Middle-Upper Triassic age for a geomagnetic pole previously quoted either as Middle or Upper Triassic. The palaeomagnetic and radiometric data from igneous rocks of the Quebrada del Pimiento Formation of Argentina, define a period of normal polarity within the Late Palaeozoic Interval of reversed geomagnetic polarity (Kiaman Magnetic Interval); the possibility of using this short normal period for geological correlation is suggested. The Late Palaeozoic geomagnetic poles now available for South America define the polar path relative to this continent fairly well; it is suggested that this polar path is also valid for Africa, South America and Africa having been joined by their Atlantic margins throughout the Late Palaeozoic and Triassic. The discrepancy between the positions of Permian geomagnetic poles of South America and Australia is pointed out. It could represent different polar shifts relative to South America and Australia and could imply that the fragmentation of Gondwana started in Early Permian times with the formation of two super-continents: South America-Africa and Australia-Antarctica-India. © 1972. Fil:Valencio, D.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Vilas, J.F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. |
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