Research project: Landscape evolution in central-eastern New South Wales

Dates

Start date:
1996

Museum investigators

  • Lin Sutherland
  • Ross Pogson
  • Larry Barron

External investigators

  • Ian Graham, University of New South Wales
  • H Zwingmann, CSIRO, Perth
  • Alice Warren, Geolological Survey New South Wales
  • David Och, Parsons-Brinckerhoff PL

Funded by

  • Australian Museum Research Grant University of New South Wales , Parsons-Brinckerhoff PL’ University of Western Sydney

Description

Landscapes around Dubbo and Wellington show a range of eroded igneous intrusions and prevailing basalt lava flows, but only had a few dating controls for the subdued inland surface. Similar intrusions and flows in the Lorne Basin appear within a more dissected coastal surface. These rocks are being mapped in detail and dated by several methods (K-Ar, Ar-Ar, zircon fission track), to compare their relative ages, erosion histories and geochemical relationships (XRD, LA-ICP-MS analyses).

The dating so far suggests the Dubbo-Wellington bodies are older than suggested by previous mapping and are mostly Mesozoic features left on a relatively old, exhumed land surface. The dated Lorne Basin bodies are also mostly Mesozoic but have greater dissection. The results at present suggest the inland region around Dubbo-Wellington suffered lower rates of erosion than areas further east, where the Mesozoic landscapes are mostly stripped away.

Preliminary dating results were fed into the 1998 New South Wales Geological Survey Dubbo 1:250 000 Sheet Explanatory Report. The project is presently being prepared for publication, New roads through the Brothers, Lorne Basin, however, have exposed further materials for more complete analysis.


Lin Sutherland
Ross Pogson
Larry Barron
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