I want to make sure age of the sediment core collected from a inland freshwater lake. Core is entirely consist with clay.There is no macro fossiles no plant fragments. This sediment could be arround 500-5000 years old. What is the most suitable method to determine the age at various core depths
Radiocarbon. Be isotopes are often used if sediments originated in subaerial settings, but I will still go for radiocarbon. Make sure you calibrate properly to consider original carbon 14 in the media (i.e. approx. +400 yrs in marine environments.
Dear Panchala you can use techniques like:
microfossils biostratigraphy
palynology
tephrochronology
magnetic susceptibility
Dear Panacha HI,
in addition to the previous answers (radioncarbon dating in case there is enough organic material to date) and of other indirect methods (biostratigraphy, tephrochronology, etc), OSL (OpticallyStimulated Luminesence) dating of soils/sediments is becoming more and more popular. However, like all the dating techniques there are some limitations.
It depends on the type of sediment (marine, lacustrine, terrestrial, aeoloian) and the desired accuracy.
Cheers,
Mike
Greetings,
I used C-14 dating for my first cores on a estuarine deposites. For my latest cores I used OSL. Both showed good results but OSL is usually a bit more expensive. Be alerted for the fact that you might find archaeological fragments (pieces of pottery, Flint, etc.) Are there archaeological sites near that area? That could also help you get a first chronological idea of a deposit.
Best of luck to your work.
JAG
Since the target core is entirely made of clay I would suggest 14-C radiocarbon dating of the bulk sediment. Just be careful that the dates are correctly calibrated. The study of varves (rhythmites) may provide further information of annual sediment supply but can be a quite time consuming proxy. OSL is only adequate if you have large quantities of quartz or felspar materials and will give you the time of the burial of sediments. Cheers!
Dear Mr. Weerakon,
did you check your samples and the the environment you are working in also for artifacts such as household remains and archaemetallurgical remains and lichen covering the rock samples? What about dendrochonology ? Even small pieces may work. U-Th disequilibria may also be of help, provided you have good analytical devices.
Best regards
H.G.Dill
I am aware on these samples. These sediments are previously interpreted related to Paleozoic glaciation happened in a glacial lake. However, I believe they are of very recent age as Mr. Panchala indicated (500 to 5000 BP). 14-C radiocarbon dating of the bulk sediment should be the only possibility since there seems to be only clay.
Certainly the best method if C 14, if not available, then you can do exposure dating method, which will give you relative age as compared to surroundings.
Carbon 14 has half life time of about 5730 a, and it can be used with high precision to determine the age, especially at its hugher limit (i.e., 5000 a). Other isotopes may fit more the lower limit (500 a).
You mentioned that you did not observe macro fossils to apply C14 dating. Hom about micro fossils such as ostracoda? If you identify some shells you can apply the C14 method easily because you do not need a big amount to do that.
Does the clay contain any organic carbon? If so, then a bulk sample could be dated by C14. Pb210 dating of the bulk clay could provide chronometric information at the younger end of your estimated scale.
Thank you all for answering my question.We have found some micro-fossils but it seems recent age(I have attached the link here). Also U/Th/Rn/Pb is not present in any depth.Therefore I guess the most suitable dating methods are bulk C14 for the older time interval(5000 a) and OSL.
can I used OSL method to identify the age around 500a ??
https://www.researchgate.net/publication/282854405_NON_POLLEN_PALYNOMORPHS_AS_PALAEOENVIRONMENTAL_INDICATOR_IN_THE_BORE_HOLE-1_FROM_WEUDA_AREA_SRI_LANKA?ev=prf_pub. )
Research NON POLLEN PALYNOMORPHS AS PALAEOENVIRONMENTAL INDICATOR IN ...
According to your discription, the following is my suggestions. If your samples contain organic material, 14C or AMS14C dating techniques could be used; If your samples contain quartz and were well bleached, OSL dating techniques are best choice. If possible, you could use these two dating techniques to date your samples independently