The age, extent and geomorphological significance of the Sassafras basalt, south‐eastern New South Wales
- 1 December 1985
- journal article
- research article
- Published by Taylor & Francis in Australian Journal of Earth Sciences
- Vol. 32 (4) , 323-331
- https://doi.org/10.1080/08120098508729335
Abstract
Basalt at Sassafras was erupted in the Middle Eocene. The K‐Ar ages average 45.3 ± 4.9 Ma on whole rock and 48.4 ± 1.9 Ma on plagioclase. The basalt is not limited to a plateau capping, but extends 150 m down into adjacent valleys. Comparison with nearby Eocene basalts shows that there was in excess of 250 m of local relief in the central Shoalhaven valley by the Early Tertiary. The basalts were extruded at high elevation, and denudation of the coastal margin of the upland was already well advanced. Post‐basaltic denudation has been very slow, and the Early Tertiary landscape is well preserved.Keywords
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