Radiocarbon Dating - Science method

I don't know about potential concentration of phytoliths in E horizons, but I do know they can be translocated in a soil profile. As a leached horizon, E horizons may have had many particle moved as well as organic materials & other soil chemicals. They would be likely to hang up in horizons with greater clay content, and especially those with greater formation of clay bridges and clay films. I had a project north of Huntsville, TX that experiences significant amounts of heavy rainfall. Many phytoliths were relocate to lower portions of the soil profile and exhibited significant abrasion, indicative of that translocation. The abrasion affected the analyst's ability to identify them, but provided a taphonomic indication that most of the phytoliths (and potentially some of the charcoal) had been moved downward out of their original depositional context.

Yes, there are recommended methods and procedures for lake sediment sampling for AMS radiocarbon dating. The following is a comprehensive guide on the recommended methods and procedures for lake sediment sampling for AMS radiocarbon dating. Lake sediment samples can be used for AMS radiocarbon dating to determine the age of the sediment and the lake's history. However, to obtain accurate results, it is essential to follow recommended methods and procedures for lake sediment sampling. The following are the recommended methods and procedures: 1. Sampling Location: Selecting the right location for sediment sampling is crucial. It is recommended to choose a location that is representative of the entire lake's sedimentation history. The location should be in a relatively undisturbed area of the lake, away from any inflows or outflows, and where sediment deposition is continuous. 2. Sampling Equipment: The equipment used for sediment sampling should be clean and free from any contaminants that could affect the radiocarbon dating results. Stainless steel corers are commonly used to collect sediment samples from lakes. 3. Sampling Depth: The depth of sediment sampling should be based on the lake's depth and the desired time resolution of the radiocarbon dating analysis. It is recommended to sample at least 10 cm intervals to capture changes in sedimentation rates accurately. 4. Sample Preservation: Once collected, it is essential to preserve the samples correctly to prevent any contamination or alteration of the sample material. Samples should be stored in airtight containers at low temperatures until they are ready for analysis. 5. Sample Processing: Before AMS radiocarbon dating analysis, it is necessary to process the samples properly. This includes drying, homogenizing, and removing any organic matter that could interfere with radiocarbon dating analysis. 6. Radiocarbon Dating Analysis: AMS radiocarbon dating analysis should be performed by an accredited laboratory using standard protocols and quality control. Following these recommended methods and procedures can ensure accurate and reliable radiocarbon dating results.

References: 1. "Guidelines for AMS radiocarbon analysis of lake sediments" by S. Juggins and A. J. Burridge, published in Quaternary Science Reviews. 2. "High-resolution AMS radiocarbon dating of annually laminated sediments from Lake Żabińskie, Poland: Varve chronology for the last 6000 years" by M. Blaauw et al., published in Quaternary Science Reviews. 3. "Radiocarbon dating of lake sediments" by P. Appleby and F. Oldfield, published in Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

Thank you. As you can see, climate change is important in that it makse "us" think in creative ways.

Lou

Thank you for your suggestion. The radiocarbon dates focus on bulk organic matter, i.e. total organic carbon content( TOC) while the OSL dates focus on the quartz grains for luminescence study. As the area lies on plain land there are no hydrothermal influences

I'm also looking for originals from Telfedyne Isotopes. Hoping somebody can publish the original data.

If you are able to split your soil samples into "paragenetic associations" (be it geogenic or anthropogenic) and if the sample batches you are interested in are big enough so as to rule out contamination by the matrix there is no objection to carry out radio-carbon dating in the way you desire.

DILL, H.G. (2009) Pyrometallurgical relics of Pb-Cu-Fe deposits in south-eastern Germany: An exploration tool and a record of mining history .- Journal of Geochemical Exploration, 100: 37-50.

DILL, H.G., TECHMER, A. and KUS, J (2013) Evolution of an old mining district between 725 and 1630 AD at the boundary between Thüringen and Bayern, SE Germany, using mineralogical and chemical markers, radio-carbon dating and coal petrography of slags.- Archaeological and Anthropological Sciences, 5: 215-233.

Available on request for download from the RG server

H.G.D.

Probably option C, those are what we would call "archaeological theories" that set the floor to explain what we find in the archeological record by integrating them into a set of principles that explain the evolution and behavior of human societies.

Thank you. I think I get it .

Glass shards and tephras have been reported from the late Early Miocene sediments (ca. 20 my old) of Andaman Islands.

Hi,

Extrapolation beyond a dated point is always dangerous since you don't have more information. If the sedimentation rate within the dated section remains quite stable and the sedimentology doesn't change too much you could very carefully assume a constant sedimentation rate and extrapolate linearly. However, you'll never be certain and it'll likely be picked up by reviewers as well if the age-depth model in the undated section is important for your overall discussion.

Extrapolation is possible in age depth model scripts such as Bacon ( https://chrono.qub.ac.uk/blaauw/bacon.html ) and Clam ( http://www.chrono.qub.ac.uk/blaauw/clam.html ).

Cheers,

Loic Piret

Hello Praveen,

it seems that the book is available at Abebooks.com

Hope you find it!

Roberta

Radiocarbon is probably the most cost effective. See if others are also interested in getting dates from the samples/period - you may be able to split the costs.

Also bear in mind the precision of radiocarbon dating is not always great depending on the period. What kind of samples is it you are looking at?

You could easily test the nuclear contamination hypothesis by ¹³⁷Cs dating the bone. Fossil fuels also have the Suess Effect on ¹⁴C dates.

In a paper by Hebda et al. (2008) we radiocarbon date vole bones on a debris flow / sheet flood fan between much younger soil horizons.

"The bones occur between two prominent Ah horizons - the upper one

dating to 5520 ± 150 BP, and the lower one dating to 7132 ± 80 BP . The bones, however, yielded uncalibrated radiocarbon ages of 11 507 ± 52 years BP and 12 567 ± 49 years BP , 5000–6000 years older than the upper and lower bracketing soil horizons. "

The vole unit must have been remobilized from its original position and incorporated in a debris flow some 5000-6000 years later.

So the lesson here - understand the geomorphic context, and date more rather than less. In this case, only relying on the bracketing ages would have yielded results that were substantially too young.

Johan, I appreciate your perspectives on this question. Theories explain large scale processes in the natural world, i.e., movement of objects, evolution, the structure of the universe, etc. I like your characterization of the physics & chemistry behind dating methods as laws of nature, it's just the nuts & bolts of how our dating methods work. I don't know if Maria's initial question also concerned the statistical models used to evaluate the raw data from these methods to determine a range of dates from any particular sample, but I think you and I are in agreement these are just archaeological methods and not any higher level of explanation about the archaeological record, our questions about the past, or hopes to better understand human behaviors and our evolution.

I work with archaeological and palaeo-landslides sediment samples which contain sediments comprised of silt/sands/rocks and have submitted many charcoal samples for AMS dating. Floatation in water does not always work since the charcoal will be coated in silt. I use a processing technique to concentrate charcoal from the silt/sand/rock fraction. Dependent upon the sample volume, I place ~500 ml in a 2L beaker with a handle. Using a water spray hose, I swirl the contents by spraying along the interior walls of the beaker to create a vortex of organic (charcoal) material. I immediately decant the swirled organics onto nested sieves (0.85 and 0.425mm mesh opening). This is repeated many times to fully obtain all of the charcoal pieces. This wet concentrate of charcoal is then picked under a microscope using stainless steel forceps. For very small charcoal fragments, I use a glass micropipette fitted with a bulb for suction. Since some mineral grains exist in the charcoal concentrate, I clear the grains away from the charcoal (under a microscope) and then suction the charcoal by clamping the bulb (no air in the bulb) and slowly pipette charcoal pieces releasing the bulb slowly. Should there be too much water (after pipetting) the charcoal into a smaller, separate glass petri dish, you can pipette the water off for quick drying of the charcoal.

Generally - sodium hypochlorite ( NaOCl ) belongs to a neutral color chloride group. Sodium hypochlorite is an oxidized substance, in the center of acetic acid, affecting the potassium iodide with iodine release. The chlorometer grade calculation of the solution is equal to the N( Normality ) x 11.2

I'd prefer to say not "most effective", but "most reliable". And that would be without a doubt ¹⁴C dating. After all, there is a Nobel prize awarded for the technique (to Libby in 1960). I am especially leery of XRF with non-homogeneous layered samples, because there is no way to control or really predict how deep the X-rays will penetrate, and therefore what will be detected.

It could be a hormonal or hydraulic/electrical signal enabling communication with other nearby trees. See: Communication in Plants pp 333–349, Long-Distance Signal Transmission in Trees by Stefano Mancuso and Sergio Mugnai :)

Kenneth is discussing dealing with estimated dates of total extinctions. In fact, for individual species, determining time of extinction is very dependent of the observations at your disposal. In the case of the Mammoth, for many decades, it was thought that they died out at the end of the last major cold event.  Subsequently, it has been found that they persisted in living until 4ka on Wrangell Island in the absence of Man.

There can also be problems using DNA.  Thus the oldest fossil from polar bears is about 1210 Ka.  Whole cell DNA analysis suggests that they died out about 600 ka B.P., whereas  DNA analysis of part of the nucleus suggests 400 ka. Thus there are problems with the choice of your data source that render mathematical estimation rather dependent on the data source rather than computational statistics.

Stuart.

COSTAMAGNO, S., et al. Bone a fuel source: the effects of initial fragment size distribution. Gestion des combustibles au paléolithique et au mésolithique. BAR International Series, 1914, p. 65-84.

Gabucio, M. J., Cáceres, I., Rosell, J., Saladié, P., & Vallverdú, J. (2014). From small bone fragments to Neanderthal activity areas: The case of Level O of the Abric Romaní (Capellades, Barcelona, Spain). Quaternary International, 330, 36-51.

No other isotopes besides stable carbon and oxygen were studied. Samples of the beachrocks were analyzed in a scanning electron microscope with coupled EDAX. In the cement of these rocks (it is not about soil) these isotopes are the main constituents.  And as previously answered, the source is shallow marine water in contact with fresh water.

Thank you Andre for your answers. I was suspecting that the same aged samples could be used as one combined, This is definitely good news. The samples are however very small and the etching has to be minimal to preserve as much as possible of the samples. I wonder if I could Carbon date the carbonated material in the matrix, but the diagenetic alterations due to the surface ratio would have had a significant effect on the re-crystallization and atmospheric CO₂, so this is why I ruled this out.

Thank you again for your reply!

Hi Stefan,

Yes, radiocarbon dating of burned skeletal remains is routine procedure nowadays. It is a bit different than conventional radiocarbon dating since it targets the structural carbonate of the mineral fraction rather than the organic fraction. However, it works better (if not exclusively) on completely calcined remains (usually burned at temperatures higher than 700/800º C). This is to make sure that no organics are left on the bones.

Here's some bibliography on that matter:

Lanting JN, Aerts-Bijma AT, and Plicht Jvd. 2001. Dating of cremated bones. Radiocarbon 43(2A):249-254.

Olsen J, Heinemeier J, Bennike P, Krause C, Hornstrup KM, and Thrane H. 2008. Characterisation and blind testing of radiocarbon dating of cremated bone. Journal of Archaeological Science 35:791-800.

Van Strydonck et al. 2005. 14C-dating of cremaed bones, why does it work. Lunula Archaeologia Protohistorica XII: 3-10

Zazzo et al. 2009. Radiocarbon 51(2):601-611

All the best,

David

Bomb method requires a local atmosphere 14C model and AMS. In treees some spring ascending sap can hold remobilized sugars from roots, and it would be easier to collect. For bomb a quite ref is from Reimer et al. RADIOCARBON, Vol 46, Nr 3, 2004, p 1299–1304

I did a fair bit of this over the years, and yes vitrinite reflectence does not help much with the timing of maximum burial but when combined with fission track dating and track length analysis and using that information to create a burial history plot you are on your way to getting to a Tt path.  Please try both forward models and inverse model to best understand the thermal history.

Please also browse the Radiocarbon at: http://journals.cambridge.org/action/displayJournal?jid=RDC

 I Thank all who answered this question .After having gone through all the answers I am of the opinion that relative ageing of the paper is possible but not the absolute one that is in precise years months and days.

THANKS AND REGARDS.

Dear Aaron,

14C datings are reported in either of two forms, which always start with the laboratory-identification code like OxA (Oxford), GrA (Groningen), MAMS (Mannheim), just to name a few here from Europe, followed by the lab-number. Then you either get a date followed by its confidence-interval or the percentage modern radiocarbon with its standard error. Here two real life examples from a paper that we published last month (see below).

J-8544 842±23 BP 90.05 0.26

J-8543 665±24 BP 92.06 0.27

Now if you feed these data into either CALIB or OxCAL (I happen to use the latter) you get the calibrated data. Now look on the graphic representation (with Oxcal there is the dropdown menu showing table, where you choose ‘single plot’). With the first value you see the probability-distribution in red on the vertical axis, which is then ‘projected’ on the calibration curve, which results in the grey distribution on the horizontal axis. This procedure results in the calibrated date, which lies with 95.4% probability between 1161 and 1255 AD.

Now take the second date and feed it into the program. In this part of the curve there is a nasty wiggle which causes the distribution to hit the curve twice, giving two well-separated probability intervals. Your 95.4% probability is now split nearly equally between the two date-ranges of 1278-1316 and 1355-1390 AD. So you can be pretty sure your piece of charcoal doesn’t date to any period outside these two intervals (including the range of 1317-1354), but there is absolutely no way to decide in which of the two humps the actual date lies. And this is exactly the effect you get with any date younger than ca. 270 BP, which is spread out over at least three intervals, as the calibration curve (which corresponds to the concentration of 14C in the air), starts to yo-yo very badly after ca. 1520.

Hope this clarifies the procedure a bit and shows why 14C after the (European) Middle Ages aren’t of much use.

Greetings,

Rengert

There is an interesting attempt by: Dietzel, Martin, Kolmer, Hans, Pölt, Peter & Simic, Sanja 2008. «Desert varnish and petroglyphs on sandstone - Geochemical composition and climate changes from Pleistocene to Holocene (Libya).» Chemie der Erde 68: 31-43.

Hi Wassef,

the AAA protocol normally is used for the chemical pretreatment of charcoals, woods or vegetable remains. The first acid attack (HCl 1% till stable pH under 1) is used to remove carbonates and fulvic acids, the basic treatment (NaOH 1% at 60°C for 4 hours) remove the humic substances due to the burrial time while the last acid treatment remove the CO2 adsorb from the atmosferic air duringe the previous step. In the case of bone samples, generally, the chemical treatment consists in LOGIN protocol for the collagen extraction. In particular, after the size reduction of samples (not powered) and its washing, put the sample in acid (HCl at 1%+ some drops of HCl at 37%) till the pH is stable under 1 (monitoring pH value and adding HCl for several days). This step is konwn as deminaralization. So the sample is washed with ultrapure water and put in 1600 ul of acid solution at pH 3 for 16 hours at 85°C (gelatinization). At this point the solution needs to be filtered through the use of glass syringe equipped with 0.45 uM silver filter. 

I wouldn't worry about the Acomb being over 100%, as long as your Acomb % is greater than the An your test passes, if it's less than the An it fails. That's the most important aspect of the Combine. You can post your question on the OxCal group message board and you will get an answer your looking for. Hope this helps. 

Dear Isabel, 

As suggested by others, most commentators recommend dating suspension-feeding bivalves rather than gastropods (the latter often ingesting 'old' carbon from the environments they live in). There are some useful guides to marine shell taxa selection for dating, including the Oceania Marine Reservoir Dating Project website at: http://www.radiocarbondating.com/imagesOMR/homepageframe.html. Two papers led by Fiona Petchey comparing various bivalves and gastropods in the Caution Bay sequence at Caution Bay in Papua New Guinea which appeared in Radiocarbon (2012) and Archaeological and Anthropological Sciences (2013) are very useful too.

However, I think your major issue will be the impact of limestone on radiocarbon activity in all of the taxa in your deposit. Fiona Petchey as a very useful summary of some of the impacts of these issues with examples from the Pacific in her paper available for free download at: http://press.anu.edu.au/wp-content/uploads/2011/05/ch117.pdf

Good luck with your research!

Regards,

Sean

how about this one?:

Guilderson, Tom P., Paula J. Reimer, and Tom A. Brown

2005 The Boon and Bane of Radiocarbon Dating. Science 307(5708):362-364.

Dear Peta,

You could find a answer in the paper of Kwiecien et al. (2008) entitled: ``ESTIMATED RESERVOIR AGES OF THE BLACK SEA SINCE THE LAST GLACIAL`` RADIOCARBON, Vol 50, Nr 1, 2008, p 99–118.

Dear Jos,

the choice for the calibration is based on environmental considerations. If you believe that your shells lived in a marine environment you can use Marine 13. But beach barrier could be a more complex environment so if the shells lived in a lagoon you can take into consideration the possibility of a different calibration.

Best regards,

Luigi Vigliotti

It depends. What kind of fossil you are talking about? Every absolute age estimation has its limits in material and method. A lot of geologists and palaeontologists would insist, that something that can be dated by C14 can not be called "fossil" because of the limited time range of this method.

Without more specific informations about your object of interest and issues you want to study nobody can give you specific answers to your questions.

Dear Julie,

depending on the affected gene... CLP is often the result of both genetic and environmental factors. cleft lip may also be part of a syndrome

e.g. Van der Woude syndrome (VWS) is a rare congenital genetic dysmorphic syndrome characterized by lower-lip fistulae, cleft lip with or without cleft palate, or only cleft palate. In this condition the IRF6 gene is mutated..

cheers and success!

Frank

There is the radon-B database which is growing and also covering this area.

No, this is not the major problem. Imagine that you know very precisely what was the atmospheric 14C/14N ratio in the arbitrary time.

Since metabolic chemical processes in each organism/plant/... are unique, it utilise carbon and nitrogen at various rate. I would expect that for example oak tree gathers nitrogen faster than elephant (this information is without guarantee of course). Moreover, amount of utilised nitrogen and carbon could possibly depend on local conditions, too (food, soil, etc...)

Therefore before the death of the organism ratio 14C/14N can vary. Furthermore, even after burial the sample is in contact with water, soil and so on - and ratio 14C/14N can be modified.

But no matter how carbon - saturated is food or soil, carbon 12, 13, 14 will enter all the chemical pathways in the (nearly) same rate. I used term nearly because heavier carbons aren t so mobile than lighter one, what slightly reflects to the chemical reaction kinetics. So the ratio 14C/12C or 13C/12C depends only on the natural occurence in the environment and is suitable indicator of sample isotopic fractionation

Here in Italy, we prefere the term of "Sciences applied to Cultural Heritage", University courses on these topics (including physical methodologies, such as C14 dating, XRF, Raman Scattering, IR fluorescence and many other, as well as statistics, paleo-botanics, anthropolgy, etc) are held in many Italian Universities both at degree and PhD level. Of course a Doctor in Sciences applied to Cultural Heritage is not an archaeologist, however he is a professional whose presence in any archeological mission is precious. For myself, I am an astronomer and I joined a number of archaeological mission when professional archeologists asked me if it was possible to confirm or deny on a physical base if the hypothesis of an astronomical meaning in some artifacts was acceptable. But I just measure angles and make astronomical computation, giving a statistical evaluation of the hypothesis they suggested. I will never try to make an hypothesis on an archeaological artifact by myself, since I have not a professional knowledge on the cuture that produced the artifact.

Hello!

Thanks for your reply, and for the link provided, that I have not checked yet. Bayesian statistics' details are, admittedly, too deep water for me. I, for me, do grasp the basic principles and the underlying mechanics, but my background is not so extensive to let myself play around with Bayesian modeling independently from the Bayesian radiocarbon modeling facility (i.e., OxCal).

As for modeling in general, I have recently come across the problem of evaluating Logistic Regression models and I am in due course in deepening my knowledge on the topic. And I have indeed found an interesting R package for that purposes (i.e., validation and calibration).

Cheers

Gm

The peaks of chernobly and bomb test are usually very useful for creation of historical profiles.

pMC is percent modern carbon, with modern or present defined as 1950. Of course as calibration is needed anyway you could just apply the formula and give a negative radio carbon age of minus 2150 years bp, but that'd be rather confusing. Since the atmospheric atom bomb tests of the fifties and sixties atmospheric radio carbon values have gone haywire, although they're nearing normal again now. So for anything younger than 1850 AD or so laboratories often do not give an age but the raw radiocarbon measurement as percent of the standard. It is up to you to try and make sense of it in the context of sample.

Hi Mustapha. It all depends on the age you expect to have at the bottom of the core. I used to have up to 2000years in 1m of peat. We are even working a 3-m core which is 40kyrs...

So, 3-4 14C date range finders along the core would be nice, then you can refine it with more dates for specific intervals where you want to have a precise timing of events for the proxies you are investigating. And 210Pb is definitely a plus. Check Mires and Peat volume 7 for an overview of peat protocols and dating. Good luck.

First of all, you need to define if these roots are young organic matter (observe the characteristics), because if is true you can use a radiocarbon data (e.g. link).

Usually you report the radiocarbon data with 1-sigma error. That mean that if you analyze the same sample many times, 68% of the values will be in the range of average - 1-sigma and average+1-sigma. If you use 2-sigma, this means that approximately 95% (95.4%) of your measurements will fall on that range. So overall, as you want to bee more confident then larger the uncertainty will be. For more information search for "uncertainty" keyword.

your argon in a sample is a mixture of radiogenic 40Ar (a function of time and 40K content) and initially trapped 40Ar. You do not know the amount of either of two a priory. To distinguish between the two you assume that initially trapped argon has certain isotopic composition, which is equal to present-day atmosphere (40Ar/36Ar ~ 300, the exact value is not important if the Cassignol Gillot technique, mentioned above, is applied). This assumption if, however, may be incorrect (that is quite often) for minerals crystallized in magma chamber, but this assumption is usually correct for minerals crystallized on surface. That is why it is essential to date by K-Ar a well-crystallized matrix of a volcanic rock (likely the matrix minerals crystallized from degassed magma, which was in equilibrium with atmospheric argon).

Separate dating of phenocrysts and matrix by K-Ar may help if the initial argon in all minerals had the same 40Ar/36Ar ratio (thus only if our assumption is correct). In that case you can construct an isochron in the following coordinates 40Ar/36Ar - 40Ar/40K. If the assumption about the atmospheric argon is incorrect you will not get statistically meaningful isochron.

So you can use it as a test for accuracy.

However, this way is technically complex and time-consuming.

Ar/Ar method with stepwise-heating (either by laser or in oven) is better because you have inner criterion of the age reliability such as plateau and isochron.

You can see it from my paper I gave reference above, and there is a large number of literature on that topic.

you can look at Pessenda et al 2006 or Tonneijck et al 2008 - both published in Radiocarbon, among several pubs in this area. But the reliability of wet chemical oxidation techniques for use as indices of OM stability has been a topic of intense debate in the biogeochemistry and soil science communities over the last decade (see von Lützow et al 2008 JPNSS, Kleber 2010 Environmental Chemistry and Schmidt et al 2011 Nature for further discussions)

I took the CalPal-download offline in February this year (2013) for non-scientific conflict reasons but CalPal is still available (personalised) to researchers world-wide. Please send me a mail and I will send you a link from where you can download the software package (Windows OS).

I found the paper - thanks.

I´m not sure about ecofacts - in any case not really what I would call artifacts. During excavation we do floatation of sediment for taking samples of (usually charred) botanic macro-remains. The recovered material is first studied by our (palaeo-)otanists and then we usually give some of the short-lived material for radiocarbon-dating (e.g. twigs - we want to avoid the "old-wood-effect" - juniper can become several hundred years old before being felled).

The problem is that we can date the archaeological material fairly precisely (sometimes), e.g. Greek sites can not exist in the area before the conquest by Alexander the Great in 329/328 BC, or Persian (Achaemenid) material can´t be there before the conquest by Cyrus, in the mid 7th Century BC. However, even the short-lived plant remains at such sites give C-14 ages that are too old, not just by a little, but by 70-200 years.

I observe that the "mistake" lessens the further I go downstream and away from the mountains.

Although we don´t really know enough about past climate in the region yet, at least some of the rivers are fed by glacier-water even today - so I started wondering whether possibly we have an old-water effect even in the short-lived plant remains. The natural precipitation is certainly insufficient for agriculture, which was practiced in Antiquity (we even know some of the canals) so mountain water was and still is certainly "fed" to the plants, even cereals.

My botanists think the explanation is a possibility, but others say that most of the carbon is taken up by plants through photosynthesis from the air - in that case clearly "old" water should not have any or only little effect.

I can´t really find precise studies with data on how much carbon in plants comes from water and how much from the air - thís would be quite an important aspect.