Abstract
JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 108,
2282,
16 PP., 2003
doi:10.1029/2002JB001921
Paleomagnetism of the Newcastle Range, northern Queensland: Eastern Gondwana in the Late Paleozoic
Department of Earth and Planetary Sciences, Macquarie University, Sydney, New South Wales, Australia
Department of Earth and Planetary Sciences, Macquarie University, Sydney, New South Wales, Australia
CSIRO Division of Exploration and Mining, North Ryde, New South Wales, Australia
CSIRO Division of Exploration and Mining, North Ryde, New South Wales, Australia
The Newcastle Range is an extensive (2500 km2) and well-exposed caldera system erupted on the trailing edge of Eastern Gondwana between 325 and 295 Ma. Paleomagnetic samples were collected from ignimbrites and associated microgranitoid intrusions from the central, northern and southern calderas from which three components of magnetization are recognized. Component 1 is considered to be a viscous magnetization acquired during the Brunhes Chron. A presumed Permian component, C2, is found in seven paleomagnetic sites with a mean pole at 30.9°S, 139.7°E (K = 13.9, A95 = 16.8°, ASD = 21.7°), agreeing with previously reported Permian data from Australia. Carboniferous units have a well-defined characteristic component, C3, distinguished by dual polarity (predominantly reversed) and moderate to steep inclination directions. Paleomagnetic polarities in the Newcastle Range Volcanics are formation dependent and new constraints on the timing of Carboniferous volcanism (∼325–317 Ma) are consistent with recent reanalysis of the base of the Permo-Carboniferous Reversed Superchron (PCRS). A mean paleomagnetic pole, calculated from 15 VGPs, lies at 63.4°S, 125°E (K = 26.22, A95 = 7.6°, ASD = 15.8°), suggesting that Australia remained at midlatitudes into the Middle Carboniferous. This paleomagnetic pole is consistent with similarly aged poles from Western Gondwana, the conformity of which indicates contributions from nondipole components of the Earth's paleofield were probably not significant in the time immediately preceding the PCRS.
Received 10 April 2002; accepted 23 January 2003; published 3 June 2003.
Citation: (2003), Paleomagnetism of the Newcastle Range, northern Queensland: Eastern Gondwana in the Late Paleozoic, J. Geophys. Res., 108(B6), 2282, doi:10.1029/2002JB001921.
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