A Synthesis of Australian Cenozoic Palaeomagnetic Results
Large numbers of K-Ar determinations have now been made on the Cenozoic volcanic rocks of eastern Australia. These age determinations make it possible to synthesize the palaeomagnetic results from 357 lava flows studied to date by dividing them into six age groups ranging from 60 My to Recent. We us...
| Published in: | Geophysical Journal International |
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| Main Authors: | , , |
| Format: | Text |
| Language: | English |
| Published: |
Oxford University Press
1974
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| Subjects: | |
| Online Access: | http://gji.oxfordjournals.org/cgi/content/short/36/1/141 https://doi.org/10.1111/j.1365-246X.1974.tb03629.x |
| Summary: | Large numbers of K-Ar determinations have now been made on the Cenozoic volcanic rocks of eastern Australia. These age determinations make it possible to synthesize the palaeomagnetic results from 357 lava flows studied to date by dividing them into six age groups ranging from 60 My to Recent. We use the criterion that palaeomagnetic poles with VGP co-latitudes > 40° are intermediate between normal and reversed, as has been demonstrated in Iceland. Overall 11-15 per cent of flows are classified as intermediate in this way, whereas only 3 per cent of flows with ages < 5 My and 20-30 per cent in the time range 35-25 My are intermediate. The observations from the younger group are consistent with that to be expected from the known polarity time-scale for the last 5 My. Those from the older group suggest the frequency of reversals was much greater than had previously been supposed during the mid-Tertiary. The apparent polar wander path derived from these results shows a distinct zig-zag with a westerly excursion around 30 My and a knee around 18 My. |
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