So I’ve been recently trying to find studies conducted on the possibilities to Amino Acid-date corals. So far I have only found studies that have looked into determining the age of Porites (Erica J. Handy et al., 2012) and Acropora palmata individuals (P. J. Tomiak et al., 2016). I would however be interested in using A. pruinosa individuals, as this is the most abundant species in my field study. I would be using the intra crystallised proteins to analyse the D/L ratio for a few amino acids.
The main reason why I would be using the AAR method compared to U/Th or Carbon dating is the prices. AAR would be more suitable to my sediment core sampling as I would like to date quite a few samples and Carbon dating would be way too expensive for multiple dating’s. The Uranium Thorium dating method would be also suitable but this method has not proven to be liable in previous studies where I’m working at the moment. Would I however have to carbon date calibrate the A. pruinosa individuals before I start using the AAR method to date all my samples? Or is it possible to determine the ages just based to AAR analysis?
I’m also treating my samples with 60 ° C prior to analysing them. This is because I dry them in the oven after retrieving a sediment core and after the material is sorted. I dry my sample for 48 h, but will this affect the racemization analysis and result? My sample are also collected from the sea floor usually at a 5 m depth. The cores are usually around 40 cm long and I would be dating the bottom, middle and top part of the core using the same species.
Articles:
P.J. Tomiaka, M.B. Andersena, b, , , E.J. Hendya, c, E.K. Potterb, K.G. Johnsond, K.E.H. Penkmane. The role of skeletal micro-architecture in diagenesis and dating of Acropora palmata. Volume 183, 15 June 2016, Pages 153–175
Erica J. Hendy, Peter J. Tomiak,a Matthew J. Collins, John Hellstrom, Alexander W. Tudhope, Janice M. Lough, and Kirsty E.H. Penkmanc. Assessing amino acid racemization variability in coral intra-crystalline protein for geochronological applications. Geochim Cosmochim Acta. 2012 Jun 1; 86(9-2): 338–353.
Hi Stefan,
In past unpublished studies, I have attempted to determine relative ages of corals using AAR, but have found the results to be far more variable than either mollusks or whole-rock sediment samples. That said, if the samples are well preserved chemically and mineralogically, and from clear stratigraphic context, it might be worth a pilot study. AAR will provide only relative ages, but should be able to distinguish Pleistocene from Holocene age samples. A substantial database of radiometrically calibrated AAR samples would be needed to estimate numerical ages.
Samples must be air dried and not oven heated to yield reliable results. The temperature history of the ocean floor location might be available through other proxy methods.
Best regards,
Paul Hearty
- Badges
- Science topic
- Similar topics
- Analytical Chemistry
- Extraction