The development of the Princess Charlotte Bay chenier plain: New results and insights

- We used OSL and radiocarbon to identify a new depositional chronology from a different part of the chenier plain
- At least 11 chenier ridges were built between 4000 yr BP and 820 yr BP at the new study location
- The depositional chronologies are similar at two locations in Princess Charlotte Bay
- Differences across Princess Charlotte Bay are apparent in terms of chenier ridge configuration and composition
- The internal dynamic development model is less plausible and a role should be considered for sea level fluctuations

Chenier plains record changes in the mode of coastal progradation between periods of mudflat accumulation and coarse sediment deposition. The geomorphic development of the Princess Charlotte Bay chenier plain was last considered in the 1980s and the conclusions have contributed to knowledge of muddy coastal morphodynamics. Obtaining new data through the use of luminescence dating techniques provided an opportunity to reassess previous findings. Data were obtained from the south western portion of the bay where the chenier ridges were most distinct whereas previous research had been concentrated on the far eastern periphery of the plain. Optically-stimulated luminescence age estimates and radiocarbon ages from eight of the 11 most seaward chenier ridges yielded a new depositional chronology. The recent chenier sequence in this area began forming with the establishment of the most landward chenier ridge (ridge 1) no more than 4000 yr BP. In the ~ 1500 years following this, two more chenier ridges were built (ridges 2 and 3, which were not sampled). Ridge 4 was being built at around 2400 yr BP, ridges 5 and 6 at around 2100 yr BP, ridge 7 at around 1900 yr BP, ridges 8 and 9 at around 1300 yr BP, ridge 10 (which was not dated) between 1300 and 820 yr BP, and ridge 11 at around 820 cal yr BP. Comparing the new data to previous data and conclusions yielded new insights into the Holocene development of the chenier plain. These new insights may provide a means for Australian chenier plains to inform contemporary coastal morphodynamics more broadly.