Palaeomagnetism of Some Igneous Rocks of the Middle Jurassic Chon‐Aike Formation from Estancia La Reconquista, Province of Santa Cruz, Argentina
New palaeomagnetic data for the Middle Jurassic Chon‐Aike Formation from 15 different geological units of rhyolitic porphyries, keratophyres, ignimbrites, pumicites and associated tuffs exposed at the Estancia La Reconquista, Province of Santa Cruz (48°10′S, 68°50′W), Argentina, are given. After cle...
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| Formato: | JOUR |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00168009_v39_n3_p511_Vilas |
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| Sumario: | New palaeomagnetic data for the Middle Jurassic Chon‐Aike Formation from 15 different geological units of rhyolitic porphyries, keratophyres, ignimbrites, pumicites and associated tuffs exposed at the Estancia La Reconquista, Province of Santa Cruz (48°10′S, 68°50′W), Argentina, are given. After cleaning, all the units show normally polarized magnetic remanence and the mean of their virtual geomagnetic poles is not coincident with the mean of the virtual geomagnetic poles derived from the Puerto Deseado (Valencio & Vilas) and Camarones (Creer et al.) areas. It is proposed that the most reliable palaeomagnetic pole for the Chon‐Aike Formation is that given by the mean of the 54 virtual geomagnetic poles derived from all three areas, namely Puerto Deseado, Camarones and Estancia La Reconquista. It is situated at 85° S, 163° W, with α95= 6°. Comparison of the position of this palaeomagnetic pole with the mean of the African Jurassic palaeomagnetic poles suggests that the separation of South America and Africa occurred after the Middle Jurassic. Copyright © 1974, Wiley Blackwell. All rights reserved |
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