Geological and palaeomagnetic significance of the Kulgera Dyke Swarm, Musgrave Block, NT, Australia |
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| Authors: | A Camacho B Simons P W Schmidt |
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| Institution: | Northern Territory Geological Survey, PO Box 2655, Alice Springs, NT 0871;, Australia Geological Survey of Victoria, PO Box 173, East Melbourne, Victoria 3002;, Australia CSIRO, Division of Exploration Geoscience, PO Box 136, North Ryde, NSW 2113;, Australia |
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| Abstract: | b
The Kulgera Dyke Swarm consists of olivine tholeiites which have intruded late Proterozoic transitional-granulite gneisses and granites of the eastern Musgrave Block, in central Australia. Preliminary Rb/Sr results suggest that the dolerites were emplaced at 1054 ± 14 Ma. In addition, a Rb/Sr age of 1060 ± 10 Ma on a biotite from a pegmatite indicates thermal resetting of the country rock minerals during dyke emplacement. Palaeomagnetic investigations of the dykes yield a primary thermoremanent magnetization direction corresponding to a palaeomagnetic pole at 17 S, 266E ( A 95= 12). In addition to this primary magnetization, an overprint component was present in many of the samples, providing a palaeomagnetic pole at 30S, 138E ( A 95= 24), which is similar to previous results from other central Australian rocks affected by the Alice Springs Orogeny. The results extend the area of influence of the Carboniferous Alice Springs Orogeny southward into the Musgrave Block. Further, the results provide no evidence for an earlier, Late Proterozoic, Petermann Orogeny affecting the Musgrave Block in the Kulgera region. However, the possibility that a Petermann Orogeny thermal overprint has been erased by the Alice Springs Orogeny cannot be dismissed. |
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| Keywords: | Alice Springs Orogeny Musgrave Block overprint palaeomagnetism Proterozoic Dyke Swarm Rb-Sr chronology |
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