========================================================================= Date: Thu, 7 Sep 1995 22:02:49 -0400 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "Kim A. Cox" Subject: shell dates There is presently a debate in the archaeological field that is quickly getting out of hand. Some archaeologists have claimed that estuarine shells are subject to a marine reservoir correction factor in addition to C13 correction. The theory has it that in some river systems that emerge from limestone formations, estuarine shells will uptake old carbon. Marine biologist friends of mine say this is pure bunk because the overwhelming amount of carbon uptake in large shellfish comes ultimately from phytoplanktons, which, being mainly at the top of the water column, consist mostly of atmospheric carbon. Does anyone know the answers to: 1. Is there any merit to the marine reservoir correction factor for estuarine shells in some river systems? If so, what are the factors influencing such a correction factor? 2. Along the Texas coast, the C13 correction seems to be approximately 380 yrs. for all shellfish except Rangia (which seems to go about 290 yrs.). What are the reasons for this anomaly? 3. Is anyone aware of paired corrected and calibrated dates of charcoal and shellfish? 4. How confident are radiocarbon dates on oysters? Anyone aware of paired dates with other shellfish, bone or charcoal? Much thanks for any help in this regard. Kim A. Cox KimACox@aol.com ========================================================================= Date: Fri, 8 Sep 1995 15:31:42 +1200 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Tom Higham Subject: Re: shell dates >There is presently a debate in the archaeological field that is quickly >getting out of hand. Some archaeologists have claimed that estuarine shells >are subject to a marine reservoir correction factor in addition to C13 >correction. All conventional radiocarbon dates should be corrected for isotopic fractionation or deltaC13. The difference between dC13 corrected and dC13 uncorrected shell dates is about 400 years or so. Any basic radiocarbon text will explain the biochemical reasons for fractionation and the need to correct for its effect. The majority of radiocarbon labs correct for isotopic fractionation. The marine reservoir effect is a completely different situation. Because of the upwelling and mixing of deep radioactively depleted waters and the delay between the exchange of CO2 from the atmosphere to the oceans there is a difference in the age of the ocean and the atmosphere (and terrestrial animals and plants) of about 400 yr. That is, if you date a shell and a piece of wood (both corrected for isotopic fractionation!), of identical historical age, the shell will be, on average, 400 yr too old. Coincidentally this is about the same age correction as the difference between a dC13 uncorrected and corrected date. The origin of your misconception began when people realized that these two effects basically cancel each other out, ie, a dc13 uncorrected shell date gives you about the right real age. Nowadays, when dc13 corrections are commonly made by most labs one is concerned more with correcting shell dates for the reservoir effect. So there are two different effects you are talking about here and when you wrote... >Some archaeologists have claimed that estuarine shells >are subject to a marine reservoir correction factor in addition to C13 >correction. you were basically right. The theory has it that in some river systems that emerge from >limestone formations, estuarine shells will uptake old carbon. Marine >biologist friends of mine say this is pure bunk because the overwhelming >amount of carbon uptake in large shellfish comes ultimately from >phytoplanktons, which, being mainly at the top of the water column, consist >mostly of atmospheric carbon. Not quite, studies have shown that shellfish obtain a variable mixture of carbon from dissolved inorganic carbon from the ocean and metabolic carbon from filter feeding plankton/diatoms etc. In areas where there is a significant amount of dissolved bicarbonate originating from geological formations of infinite age, there may be a hard water effect, ie, shellfish dates will be spuriously old. The shellfish will incorporate some of this carbon into their shell mantles. This is well documented. Does anyone know the answers to: > >1. Is there any merit to the marine reservoir correction factor for estuarine >shells in some river systems? If so, what are the factors influencing such a >correction factor? > Check out Little's (1993) paper in Journal of Archaeological Science for dscussion of this issue with reference to the US Eastern seaboard. There are some possible errors involved eg, shellfish may uptake larger amounts of carbon material from terrestrial sources and yield ages at odds with those expected, based on shell-charcoal pairs. There may be a hard water effect as well. Some background research is needed into the river/estuarine system involved prior to going ahead with radiocarbon dating. There are no hard and fast rules. Stuiver and Braziunas' Delta R, or local reservoir correction accurately corrects dates from the eastern US according to Little. Tom Dye's recent paper in Radiocarbon concerned with dating shell in Hawaii also contains some data on this problem although there are some more serious problems there. >2. Along the Texas coast, the C13 correction seems to be approximately 380 >yrs. for all shellfish except Rangia (which seems to go about 290 yrs.). What >are the reasons for this anomaly? > Variation in dC13 values which is what you are talking about reflect the dc13 values of the environment of the shellfish. Marine shells should give dc13 values between +4 and -2 per mille. Riverine shells about -11 to -15 and shells from large clear lakes between -9.2 and -1.5 per mille. Find out the dC13 values for the samples. >3. Is anyone aware of paired corrected and calibrated dates of charcoal and >shellfish? There are alot of examples of paired shell-charcoal dates, I can email you a some references if you want. >4. How confident are radiocarbon dates on oysters? Anyone aware of paired >dates with other shellfish, bone or charcoal? > Here in New Zealand, oysters (Ostrea lutraria) seem to yield reliable ages when dated. I am not sure about elsewhere though. >Much thanks for any help in this regard. > >Kim A. Cox >KimACox@aol.com Cheers, --------------------------------------------------------------------------- Dr Thomas Higham, * Email: Thigham@waikato.ac.nz Research Officer-Archaeological Dating * Phone: +(64) 07 838 4278 Radiocarbon Dating Laboratory, * GlobalFax: +(64) 7 838 4192 University of Waikato, * WWW server (with Online Hamilton, * C14 submission forms):- NEW ZEALAND. * http://www2.waikato.ac.nz/c14/ --------------------------------------------------------------------------- ========================================================================= Date: Fri, 8 Sep 1995 08:09:46 -0600 Reply-To: palynolo@geo.arizona.edu Sender: Radiocarbon Mailing List From: "Owen K. Davis" Subject: Re: shell dates > writes: > All conventional radiocarbon dates should be corrected for isotopic > fractionation or deltaC13. The difference between dC13 corrected and dC13 > uncorrected shell dates is about 400 years or so. Any basic radiocarbon > text will explain the biochemical reasons for fractionation and the need > to correct for its effect. I would very much like a reference to any basic radiocarbon text. Owen. Owen K. Davis, Ph.D. Phone 520 621 7953 Professor of Geosciences FAX 520 621 2672 University of Arizona palynolo@geo.arizona.edu Tucson, AZ 85721 http://www.geo.arizona.edu/palynology ========================================================================= Date: Tue, 12 Sep 1995 12:13:33 +0100 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Carbon14 Group Subject: New OxCal v2.18 The calibration program OxCal v2.18 is now on our WWW server http://www.ox.ac.uk/depts/rlaha The ORDER function now works properly with D_SEQ. A bug in v2.17 has been removed. This stopped the [Options|Calibration curve] menu from working so that you could not easily change calibration curves within a single set of calculations (or use Marine DeltaR corrections). The manual has been updated so that the mathematical equations should print more clearly. CBR ========================================================================= Date: Wed, 13 Sep 1995 09:17:48 +1200 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "McKee, Joseph" Subject: C14 - Gas Counting Labs "Gas-Counting Labs" Information Request. I would like to know which Labs in the Radiocarbon Community are still providing a commercial gas-counting service? This is because here in NZ, due to Governmental restructuring, there is no longer a commercial gas-counting service available. There are still researchers here in NZ would would like to know where such a service is available. I would like to be able to pass on information to these people about any labs that still offer this service. The Information I would like to pass on would be: 1/ The Laboratory - Name, address, contact person, fax, phone and or Email address. 2/ Sample cost (Most important), turnaround time etc, sample size etc. 3/ If the Lab is prepared to make known to the submitter their participation in any Intercomparison Studies (TIRI, IAEA, etc,) (I do not need to know how well you have done - but the submitter may want to know) 4/ Any printed information about the lab, submission sheets etc. that are available. These can be sent to me to copy and pass on (if you like) 5/ Any other information that the Laboratory is prepared to forward. NB!!! It will be up to the Submitter and the Lab chosen by the Submitter to sort out their own details and arrangements. I will only be passing on the information that I recieve to those requesting information. I will not be passing on any information sent to me about any "Gas-Counting " lab to another Gas-Counting lab (So don't ask for it!!!). Many Thanks. Dr Joseph W.A. McKee Rafter Radiocarbon Laboratory P.O. Box 31 312 LOWER HUTT New Zealand EMail J.MCKEE@GNS.CRI.NZ ========================================================================= Date: Thu, 14 Sep 1995 08:43:47 SAST-2 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "Lee-Thorp, JA, Julia, Dr" Subject: Re: C14 - Gas Counting Labs Comments: To: "McKee, Joseph" To Jeff McKee The Radiocarbon Lab run by Dr John Vogel, Pretoria, South Africa, provides a gas-counting service. The rates are reasonable and the lab is excellent. Address is: Dr JC Vogel, EMATEK, PO Box 395, Pretoria 0001, South Africa. Email: JVogel@ematek.csir.co.za Hope this helps. Julia Lee-Thorp Archaeometry Research Unit University of Cape Town ========================================================================= Date: Wed, 27 Sep 1995 06:29:15 -0400 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: James Aierle Subject: Trave elements/DNA in Bone I am a graduate student looking for a detailed procedure to determine the levels (ratios) of either calcium and strontium or of calcium and barium in old bones (approximately 500 years old) for research I am conducting. I need to know what the approximate ratios should be and what the best way to extract, digest and analyze these trace elements. Also, I am trying to extract DNA from these old bones. I need to find a procedure for extracting and analyzing the DNA. I would like to know if it best to decalcify the bone first of of it makes a difference if you don't. The equipment at the university where I am conducting this research is not high tech and pulverizing the bone may be a problem. Will polymerase chain reaction (PCR) necessarily need to be performed? I imagine it would since there is a minute amount of DNA present. Please send ANYTHING you have regarding either of these topics. Thank You, Jim ========================================================================= Date: Wed, 27 Sep 1995 06:46:50 -0400 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Michael Nelson Subject: Re: Trave elements/DNA in Bone Send me your snail mail address, and I will give you what information I have. My emaiol address is: MTNelson@aol.com ========================================================================= Date: Wed, 27 Sep 1995 09:23:21 -0500 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: james burton Subject: Re: Trave elements/DNA in Bone p.s. for DNA you should inquire of Noreen Tuross at CAL (Smithsonian): TUROSSN@SIMSC.SI.EDU ========================================================================= Date: Wed, 27 Sep 1995 19:52:58 -0400 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "Michael S. Pellerin" Subject: Re: Trave elements/DNA in Bone For trace elements, contact Jim Burton at Univ. of Wisconsin (phone # is 608-2624505) -- I don't have his internet address at present. For sample preparation procedures, you might try looking at an article I published in Journal of Anthropological Archaeology in 1992 (Vol. 11: 219-289). You also might look at a recent paper by Andrew Sillen and Judy Sealy in Journal of Archaeological Science (March or April 1995), Vol. 22, i think, No. 2. They do outstanding work in trace elements, as Burton does. Those are your best bets. If i can be of any other assistance, my e-mail address is sristats@aol.com -- address directly to me (Joe Ezzo). Cheers. Previous Item Next Item Connected to Microsoft Exchange