Dear all, I have some marine gastropod fossils from Sangiran Central Java Indonesia which more than 75% of the collection were found in Recent/Quarter period; the sediment was classified as Pleistocene. I wonder if somebody here could suggest me please on where and how much the cost to radio-date their geological age, perhaps their 87Sr/86Sr ration or else? as I am not at all familiar in that field. Cheers.
Norma:
You may find this link useful:
http://www.radiocarbon.com/carbon-dating-shells.htm
Best
Syed
Dear Norma,
I agree with Syed. Radiocarbon analysis is an apropriate method to estimate the numerical age of your samples.
However, you need o take care of the site-specific reservoir correction whan you want to convert the C-14 age to calendar age (so-called calibration procedure). However, you can ask help from the experts of the C-14 lab in this calibration excercise.
I have very good experience with the Hungarian AMS lab (http://w3.atomki.hu/hekal/index_en.html)
Their price list is here: http://w3.atomki.hu/hekal/arlista_en.html
As I see sample preparation costs 80Euro and C-14 analysis costs 170Euro from a gastropod shell sample.
best wishes,
Zoltan
Norma, Radiocarbon is only good back to about 40k and sometimes not even that far back. I would imagine your material is older than that. Sr-isotopes will work for older material but I personally haven't had good luck with it. I published a paper in which it was a small part and the ages were the complete opposite of what they should have been. You'd expect oldest to youngest from bottom to top in a section, our results were the complete opposite and were repeated several times. The section is not overturned and we used only a single species so - something was going on but we never did figure it out. We had other ways of dating the section so it all worked out in the end. Good luck.
Best, Chuck
Dear Chuck. Thank you for answering my query. Why do you think you could not get a good result using Sr and to what specimen did you applied it to, please? What is your comment about the fossils (ca. 75%) presence to now/Recent? Cheers.
Norma, take a look at - Powell, C.L., II, Barron, J.A., Sarna-Wojcicki, A.M., Clark, J.C., Perry, F.A., Brabb, E.E., and Fleck, R.J., 2007, Age, stratigraphy, and correlation of the late Neogene Purisima Formation, central California Coast Ranges: U.S. Geological Survey Professional Paper 1740, 32 p., http://pubs.usgs.gov/pp/2007/1740/. Our Sr results were replicated and were still the exact opposite of what they should have been. We were never able to find a reason for this.
We had used Sr analysis elsewhere in northern California on multiple taxa with very mixed results so in the above study we used just the bivalve mollusk Anadara trilineata. We would have prefered to use mollusks with calcitic shells (as opposed to aragonite) but pectinids and oysters were rare in the outcrops we studied so we went with what we had. Even given those restrictions the analysis' were the complete opposite of what they should have been.
I have no real comments on Sr in modern mollusks - never looked into it.
Best, Chuck
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