The age and palaeomagnetism of Jurassic dykes, western Dronning Maud Land: implications for Gondwana breakup
New 40 Ar/ 39 Ar data from dykes intruded into Sverdrupfjella and Ahlmanryggen, Dronning Maud Land, Antarctica, indicate that dyke emplacement commenced at c . 207 Ma and lasted until c . 178 Ma. Whereas the ages ascribed to the Karoo-age magmatism contributing to Gondwana breakup are typically infe...
Main Authors: | , , , , , , , |
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Format: | Article in Journal/Newspaper |
Language: | unknown |
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Geological Society of London
2021
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Online Access: | https://dx.doi.org/10.6084/m9.figshare.c.5612838 https://geolsoc.figshare.com/collections/The_age_and_palaeomagnetism_of_Jurassic_dykes_western_Dronning_Maud_Land_implications_for_Gondwana_breakup/5612838 |
Summary: | New 40 Ar/ 39 Ar data from dykes intruded into Sverdrupfjella and Ahlmanryggen, Dronning Maud Land, Antarctica, indicate that dyke emplacement commenced at c . 207 Ma and lasted until c . 178 Ma. Whereas the ages ascribed to the Karoo-age magmatism contributing to Gondwana breakup are typically inferred as being c . 182 Ma, the data indicate that ages older than c . 192 Ma in the broader Karoo Province are restricted to western Dronning Maud Land, Antarctica, indicating the locality where breakup was initiated. Limited palaeomagnetic data from c . 178–185 Ma dykes combined with published palaeomagnetic data from similar-aged dykes in Vestfjella and the Ferrar Province, suggest that Antarctica had already drifted/rifted significantly away from southern Africa from c . 207 Ma to c . 180 Ma, earlier than previously thought. The data, if correct, require a re-evaluation of the ages ascribed to ocean-floor anomalies used to constrain reconstructions of Gondwana and may provide insight into the history of microcontinental blocks including the Falkland Islands, Haag nunataks, Ellsworth–Whitmore block and Maurice Ewing Bank. |
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