Open AccessDating recent floodplain sediments in the H awkesbury‐ N epean R iver system, eastern Australia using single‐grain quartz OSL
Author(s) -
Sim Anna K.,
Thomsen Kristina J.,
Murray Andrew S.,
Jacobsen Geraldine,
Drysdale Russell,
Erskine Wayne
Publication year - 2014
Publication title -
boreas
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 74
eISSN - 1502-3885
pISSN - 0300-9483
DOI - 10.1111/bor.12018
Subject(s) - chronology , geology , proxy (statistics) , optical dating , quartz , fluvial , floodplain , sediment , optically stimulated luminescence , mineralogy , grain size , coring , physical geography , geochemistry , geomorphology , paleontology , cartography , geography , statistics , mathematics , structural basin , mechanical engineering , drilling , engineering
Two fluvial sediment cores taken from a floodplain of the H awkesbury‐ N epean R iver system in the S ydney region, eastern A ustralia are dated using Optically Stimulated Luminescence ( OSL ) to provide a reliable chronology essential for the management and planning of water resources. Nine charcoal 14 C ( AMS ) dates constrain these OSL ages. Quartz extracted from seven OSL samples from each of the cores was measured using both single‐grain and multi‐grain OSL techniques. Three of the single‐grain natural dose distributions appear to be well bleached, but the others appear to be incompletely bleached to various degrees. Three minimum‐age models ( MAM , MAM UL and IEU ) are applied to the single‐grain dose distributions. We conclude that these models give consistent age estimates. For one of the cores it appears to be necessary to use a minimum‐age model to obtain accurate ages, but in the other core incomplete bleaching is probably less important than postdepositional mixing and mixing during sampling. As a result, the burial age is probably best estimated using the weighted average of the individual single‐grain dose estimates. The application of multi‐grain OSL techniques to these samples results in an average apparent age overestimation of ∼200 years, which is significant for these samples, but negligible for sediments older than a few thousand years. The intention is that the chronology obtained in this study will be used in conjunction with a proxy flood record, derived from floodplain sediments, to gain an understanding of the long‐term variability in periods of high and low rainfall in eastern A ustralia.