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| Titel: |
Dating of cave sediments at Wee Jasper, New South Wales, by magnetostratigraphy |
| Auteur: |
Schmidt, Victor A. Jennings, J. N. Haosheng, Bao |
| Verschenen in: |
Australian journal of earth sciences |
| Paginering: | Jaargang 31 (1984) nr. 4 pagina's 361-370 |
| Jaar: |
1984-12 |
| Inhoud: |
Previously Punchbowl, Signature and Dogleg Caves low down in the Goodradigbee valley at Wee Jasper, NSW, could only be inferred to be younger than Early Miocene basalts on the plateau to the west. Five main quasi-horizontal cave levels, with discrete bodies of fluvial sediment at more frequent intervals, invited application of magnetostratigraphy to this sequence of passages, which are successively younger downwards, in the hope of more precise dating. Thirteen sites at 10 altitudes over a range of 31 m were sampled at 2-8 points each. The lower third of the system yielded normal polarity and so formed since 0.73 Ma. Treating the palaeomagnetic data conservatively, the upper two thirds, yielding dominantly reversed polarities, can be regarded as forming between the Brunhes-Matuyama boundary and the Jaramillo. However, this implies a drastic change in rate of lowering of local karst base level and valley incision for which there is no morphological support. Assuming a linear rate of vertical cave development, the cave began to form about 2.0 Ma; weak expression of Matuyama palaeomagnetic events to match this can be discerned and this dating is preferred. On either interpretation, the age of the system has thus been made more precise by an order of magnitude. The longer history fits better with modern ideas on the great age and slow rate of change of the plateaux of south-eastern Australia. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
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