Miers Valley

The Miers Valley was briefly visited in the 1983/84 season and a vertical sampling profile of 800 m was taken off surveyors Peak. This yielded apatite fission-track ages of 56 ± 3.7 to 43 ± 1.6 Myrs and again shows the change of uplift rate from 15 m/Myr prior to 50 Myr, to approximately 95 m/Myr (Fig. 14). It became clear from this that ages younger than 50 Myr are useless as tectonic markers as the errors in age compared to change in elevation overlap considerably. The errors in ages older than 50 Myr are small compared to change in elevation and so are good tectonic markers, a change of a few 100 m or so producing a significant age difference. It was therefore necessary to take samples from the tops of ridges or summits of peaks when they were to be used as tectonic markers. A horizontal sampling line across the Transantarctic Mountain Front was started at the coast and continued along the ridge between the Marshall and Miers Valleys almost as far west as spot height 1430 m.

Figure 14. Model for the uplift history of the Transantarctic Mountains in the Miers Valley area based on observed apatite age variation versus elevation and the estimated depth to zero age. The dramatic change in uplift rate at 50 Myr from 15 Myr prior to this and 95 m/Myr after it has been interpreted using the uplift curve from Mt Doorly (Gleadow and Fitzgerald, in prep.)