J R Southon
Biographic Data
| ID | 3643892 |
|---|---|
| NAME | J R Southon |
| GIVEN NAMES | J R |
| FAMILY NAME | Southon |
| SIGNATURE | SOUTHON J R |
| VERIFIED | No |
| TOTAL WORKS | 24 |
| TOTAL CITATIONS | 2,217 |
| WORKS AS AUTHOR | 24 |
| WORKS AS EDITOR | 0 |
| FIRST PUBLICATION YEAR | 1983 |
| LATEST PUBLICATION YEAR | 2018 |
| H-INDEX | 10 |
Radiocarbon Dating and Intercomparison of Some Early Historical Radiocarbon Samples
We performed a new series of measurements on samples that were part of early measurements on radiocarbon ( 14 C) dating made in 1948–1949. Our results show generally good agreement to the data published in 1949–1951, despite vast changes in technology, with only two exceptions where there was a discrepancy in the original studies. Our new measurements give calibrated ages that overlap with the known ages. We dated several samples at four differen…
Radiocarbon Dating and Stable Isotopic Analysis of Insect Chitin from the Rancho La Brea Tar Pits, Southern California
This paper presents the first successful methods for accelerator mass spectrometry (AMS) dating of asphalt-impregnated insect chitin from the Rancho La Brea Tar Pits in southern California. A persistent problem with stratigraphic correlation at this site is that asphalt flows are characteristically intermittent and are really discontinuous, which can result in mixing fossils of quite different ages. Direct 14 C dating of specimens circumvents thi…
A Comparison of Cellulose Extraction and ABA Pretreatment Methods for AMS 14 C Dating of Ancient Wood
We have compared accelerator mass spectrometry (AMS) radiocarbon results on wood samples at or near the limit of 14 C dating, pretreated with a standard acid-base-acid (ABA) protocol, with those obtained from cellulose prepared from the same samples by several modifications of the Jayme-Wise cellulose extraction method (Green 1963). These tests were carried out to determine the most efficient way to ensure low backgrounds in 14 C measurements of …
IntCal09 and Marine09 Radiocarbon Age Calibration Curves, 0-50,000 Years cal BP
The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the 14 C and calendar timescales as established in 2002. No change was made to the curves…
Ultra small-mass AMS 14C sample preparation and analyses at KCCAMS/UCI Facility
A Preliminary Determination of the Absolute 14 C/ 12 C Ratio of OX-I
A preliminary determination of the absolute 14 C/ 12 C ratio of the oxalic acid I standard (NBS SRM 4990B) has been made. Using an accelerator mass spectrometry (AMS) system, a known number of radiocarbon ions were implanted in a thin copper foil. The foil was then combusted with the addition of 14 C-free carrier material. This resulting gas (which had a known 14 C/ 12 C ratio) was graphitized and compared to OX-I material. This comparison yielde…
AMS 14 C Sample Preparation at the KCCAMS/UCI Facility
We present an overview of accelerator mass spectrometry (AMS) radiocarbon sample preparation and measurements, describing the technical upgrades that now allow us to routinely obtain 0.2–0.3% precision for 1-mg carbon samples. A precision of ∼1% on samples with 100 μg of carbon can also be achieved. We have also developed graphitization techniques and AMS procedures for ultra-small samples (down to 0.002 mg of carbon). Detailed time series are pr…
Magnesium Perchlorate as an Alternative Water Trap in AMS Graphite Sample Preparation
We present a brief discussion of sample preparation procedures at the Keck Carbon Cycle Accelerator Mass Spectrometer (KCCAMS), University of California, Irvine, and a systematic investigation of the use of Mg(ClO 4 ) 2 as an absorptive water trap, replacing the standard dry ice/ethanol cold finger in graphite sample preparation. We compare high-precision AMS measurement results from oxalic acid I and USGS coal samples using Mg(ClO 4 ) 2 under di…
NotCal04—Comparison/Calibration 14 C Records 26–50 Cal Kyr BP
The radiocarbon calibration curve IntCal04 extends back to 26 cal kyr B P. While several high-resolution records exist beyond this limit, these data sets exhibit discrepancies of up to several millennia. As a result, no calibration curve for the time range 26–50 cal kyr BP can be recommended as yet, but in this paper the IntCal04 working group compares the available data sets and offers a discussion of the information that they hold
Ion Source Development at Kccams, University of California, Irvine
The Keck Carbon Cycle accelerator mass spectrometry facility at the University of California, Irvine, operates a National Electronics Corporation 40-sample MC-SNICS ion source. We describe modifications that have increased beam current output, improved reliability, and made the source easier to service
Radiocarbon dates for pictographs in Ignatievskaya Cave, Russia
Samples from three charcoal pictographs at Ignatievskaya Cave, in the southern Ural Mountains of Russia, have been radiocarbon dated. An advanced antiquity was expected, with some paintings thought to be more than 10,000 years old, as suggested by the imagery. One charcoal painting, for example, resembles a mammoth. The radiocarbon date of that motif, however, dates only to 7370±50 BP. If that motif actually represents a live mammoth, it places m…
Stepped-Combustion 14 C Dating of Sediment
Radiocarbon dating of bulk sediment has long been used as a method of last resort when reliable wood, charcoal, or plant macrofossils are not available for analysis. Accurate dating of sediment is complicated by the presence of multiple organic carbon fractions, each with a potentially different 14 C activity. Additionally, the presence of carbon bound by clay minerals can significantly reduce the accuracy of a sediment age determination, with th…
Radiocarbon Dates for Beeswax Figures in the Prehistoric Rock Art of Northern Australia
Accelerator mass spectrometry radiocarbon ages have been taken for a test suite of small samples of material removed from some of the ‘beeswax’art figures found in rock shelters in northern Australia. The results indicate that we can reliably date this unique form of rock art with no noticeable damage. We had not expected to find figures of any great antiquity, and so we were surprised to find that the ages obtained spanned the time period from t…
Progress in AMS Measurements at the LLNL Spectrometer
We report on the present status of the Lawrence Livermore AMS spectrometer, including sample throughput and progress towards routine 1% measurement capability for 14 C, first results on other isotopes and experience with a multisample high-intensity ion source
Younger Dryas Climatic Reversal in Northeastern USA? AMS Ages for an Old Problem
Late-glacial macrofossils from a 10-m core from Alpine Swamp, New Jersey, were radiocarbon dated using accelerator mass spectrometry (AMS). The arrival of the first trees to the area following deglaciation is indicated by maximum percentages of spruce pollen and a date of 12,290 ± 440 yr B.P. on a single spruce needle. Subsequent spread of deciduous hardwoods was followed by the expansion of boreal taxa, including spruce ( Picea ), fir ( Abies ),…
Memory Effects in an AMS System
A sample with a 14 C concentration estimated to be greater than 30,000 Modern was inadvertently graphitized and measured in an AMS system. No measurable contamination of the cesium sputter ion source was observed. Simple cleaning procedures removed the contamination from the sample preparation system, with the exception of the reaction vessel in which the sample was graphitized. Sample cross-contamination factors were estimated for all of the pre…
Accuracy and Precision in Dating Microgram Carbon Samples
The accuracy of AMS radiocarbon determinations on very small samples has been tested by measuring a suite of microgram-sized samples of a known-age material. The total measurement precision for the smallest sample (50μg) was found to be ± 3% and the precision improved with larger sample size. The accuracies of the measurements were found to be within the measurement precisions
AMS 14C Measurements of Fractionated Soil Organic Matter
14 C measurements are reported for fractionated soil organic matter from a genetic soil sequence which was sampled several times during the period of atmospheric nuclear weapons testing. Fractionation of the soils by density followed by acid hydrolysis was successful in separating the organic matter into components with mean residence times for carbon ranging from 5 to 20 years (low density fraction) to several thousand years (residue after acid …
Ultra-Small Carbon Samples and the Dating of Sediments
Radiocarbon dates from sediment core samples are usually obtained on the whole organic carbon portion in order to use as little of the valuable sediment as possible. Such measurements may not result in an accurate chronology of the sediment because the material may include carbon from different reservoirs at the time of deposition. The development of AMS techniques for dating ultra-small (20–500 μ g) carbon samples permits dating various componen…
Improved Collagen Extraction by Modified Longin Method
A re-evaluation of the Longin collagen-extraction method shows that a lower reflux temperature reduces degradation of protein (“collagen”) remnants. This allows additional purification through ultrafiltration to isolate the >30kDalton fraction of the reflux product
C Background Levels in An Accelerator Mass Spectrometry System
The levels and sources of the measurement background in an AMS 14 C dating system have been studied in detail. The relative contributions to the total background from combustion, graphitization, storage, handling, and from the accelerator were determined by measuring the C concentrations in samples of anthracite coal ranging in size from 15μg to 20mg. The results show that, for the present system, the uncertainty in the background is greater than…
Radiocarbon Dating Blood Residues on Prehistoric Stone Tools
We report here the first radiocarbon dating of blood residues on prehistoric stone tools. The residues found on two stone artifacts were subjected to various exploratory biochemical techniques to identify the species from which they were derived and to separate a suitable sample for dating by accelerator mass spectrometry. Although these techniques need much further development and detailed testing, the ages obtained in this first study were cons…
Accelerator Radiocarbon Dating at SFU
The Simon Fraser University accelerator mass spectrometry (AMS) facility has now been in semi-routine use since the beginning of 1985. The advantages and limitations for 14 C dating are described
Tandem Accelerator Measurements of 10 Be Deposition Rates
A Tandem Van de Graaff accelerator has been modified for use in the direct measurement of natural abundances of 10 Be and 14 C. A description of the system is given and some 10 Be results on oceanographic samples are discussed
IntCal09 and Marine09 Radiocarbon Age Calibration Curves, 0-50,000 Years cal BP
The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the 14 C and calendar timescales as established in 2002. No change was made to the curves…
Improved Collagen Extraction by Modified Longin Method
A re-evaluation of the Longin collagen-extraction method shows that a lower reflux temperature reduces degradation of protein (“collagen”) remnants. This allows additional purification through ultrafiltration to isolate the >30kDalton fraction of the reflux product
C Background Levels in An Accelerator Mass Spectrometry System
The levels and sources of the measurement background in an AMS 14 C dating system have been studied in detail. The relative contributions to the total background from combustion, graphitization, storage, handling, and from the accelerator were determined by measuring the C concentrations in samples of anthracite coal ranging in size from 15μg to 20mg. The results show that, for the present system, the uncertainty in the background is greater than…
Magnesium Perchlorate as an Alternative Water Trap in AMS Graphite Sample Preparation
We present a brief discussion of sample preparation procedures at the Keck Carbon Cycle Accelerator Mass Spectrometer (KCCAMS), University of California, Irvine, and a systematic investigation of the use of Mg(ClO 4 ) 2 as an absorptive water trap, replacing the standard dry ice/ethanol cold finger in graphite sample preparation. We compare high-precision AMS measurement results from oxalic acid I and USGS coal samples using Mg(ClO 4 ) 2 under di…
A Comparison of Cellulose Extraction and ABA Pretreatment Methods for AMS 14 C Dating of Ancient Wood
We have compared accelerator mass spectrometry (AMS) radiocarbon results on wood samples at or near the limit of 14 C dating, pretreated with a standard acid-base-acid (ABA) protocol, with those obtained from cellulose prepared from the same samples by several modifications of the Jayme-Wise cellulose extraction method (Green 1963). These tests were carried out to determine the most efficient way to ensure low backgrounds in 14 C measurements of …
NotCal04—Comparison/Calibration 14 C Records 26–50 Cal Kyr BP
The radiocarbon calibration curve IntCal04 extends back to 26 cal kyr B P. While several high-resolution records exist beyond this limit, these data sets exhibit discrepancies of up to several millennia. As a result, no calibration curve for the time range 26–50 cal kyr BP can be recommended as yet, but in this paper the IntCal04 working group compares the available data sets and offers a discussion of the information that they hold
Stepped-Combustion 14 C Dating of Sediment
Radiocarbon dating of bulk sediment has long been used as a method of last resort when reliable wood, charcoal, or plant macrofossils are not available for analysis. Accurate dating of sediment is complicated by the presence of multiple organic carbon fractions, each with a potentially different 14 C activity. Additionally, the presence of carbon bound by clay minerals can significantly reduce the accuracy of a sediment age determination, with th…
AMS 14 C Sample Preparation at the KCCAMS/UCI Facility
We present an overview of accelerator mass spectrometry (AMS) radiocarbon sample preparation and measurements, describing the technical upgrades that now allow us to routinely obtain 0.2–0.3% precision for 1-mg carbon samples. A precision of ∼1% on samples with 100 μg of carbon can also be achieved. We have also developed graphitization techniques and AMS procedures for ultra-small samples (down to 0.002 mg of carbon). Detailed time series are pr…
Radiocarbon dates for pictographs in Ignatievskaya Cave, Russia
Samples from three charcoal pictographs at Ignatievskaya Cave, in the southern Ural Mountains of Russia, have been radiocarbon dated. An advanced antiquity was expected, with some paintings thought to be more than 10,000 years old, as suggested by the imagery. One charcoal painting, for example, resembles a mammoth. The radiocarbon date of that motif, however, dates only to 7370±50 BP. If that motif actually represents a live mammoth, it places m…
Radiocarbon Dates for Beeswax Figures in the Prehistoric Rock Art of Northern Australia
Accelerator mass spectrometry radiocarbon ages have been taken for a test suite of small samples of material removed from some of the ‘beeswax’art figures found in rock shelters in northern Australia. The results indicate that we can reliably date this unique form of rock art with no noticeable damage. We had not expected to find figures of any great antiquity, and so we were surprised to find that the ages obtained spanned the time period from t…
Radiocarbon Dating Blood Residues on Prehistoric Stone Tools
We report here the first radiocarbon dating of blood residues on prehistoric stone tools. The residues found on two stone artifacts were subjected to various exploratory biochemical techniques to identify the species from which they were derived and to separate a suitable sample for dating by accelerator mass spectrometry. Although these techniques need much further development and detailed testing, the ages obtained in this first study were cons…
AMS 14C Measurements of Fractionated Soil Organic Matter
14 C measurements are reported for fractionated soil organic matter from a genetic soil sequence which was sampled several times during the period of atmospheric nuclear weapons testing. Fractionation of the soils by density followed by acid hydrolysis was successful in separating the organic matter into components with mean residence times for carbon ranging from 5 to 20 years (low density fraction) to several thousand years (residue after acid …
Ion Source Development at Kccams, University of California, Irvine
The Keck Carbon Cycle accelerator mass spectrometry facility at the University of California, Irvine, operates a National Electronics Corporation 40-sample MC-SNICS ion source. We describe modifications that have increased beam current output, improved reliability, and made the source easier to service
Progress in AMS Measurements at the LLNL Spectrometer
We report on the present status of the Lawrence Livermore AMS spectrometer, including sample throughput and progress towards routine 1% measurement capability for 14 C, first results on other isotopes and experience with a multisample high-intensity ion source
Accuracy and Precision in Dating Microgram Carbon Samples
The accuracy of AMS radiocarbon determinations on very small samples has been tested by measuring a suite of microgram-sized samples of a known-age material. The total measurement precision for the smallest sample (50μg) was found to be ± 3% and the precision improved with larger sample size. The accuracies of the measurements were found to be within the measurement precisions
Memory Effects in an AMS System
A sample with a 14 C concentration estimated to be greater than 30,000 Modern was inadvertently graphitized and measured in an AMS system. No measurable contamination of the cesium sputter ion source was observed. Simple cleaning procedures removed the contamination from the sample preparation system, with the exception of the reaction vessel in which the sample was graphitized. Sample cross-contamination factors were estimated for all of the pre…
Ultra-Small Carbon Samples and the Dating of Sediments
Radiocarbon dates from sediment core samples are usually obtained on the whole organic carbon portion in order to use as little of the valuable sediment as possible. Such measurements may not result in an accurate chronology of the sediment because the material may include carbon from different reservoirs at the time of deposition. The development of AMS techniques for dating ultra-small (20–500 μ g) carbon samples permits dating various componen…
Accelerator Radiocarbon Dating at SFU
The Simon Fraser University accelerator mass spectrometry (AMS) facility has now been in semi-routine use since the beginning of 1985. The advantages and limitations for 14 C dating are described
Radiocarbon Dating and Intercomparison of Some Early Historical Radiocarbon Samples
We performed a new series of measurements on samples that were part of early measurements on radiocarbon ( 14 C) dating made in 1948–1949. Our results show generally good agreement to the data published in 1949–1951, despite vast changes in technology, with only two exceptions where there was a discrepancy in the original studies. Our new measurements give calibrated ages that overlap with the known ages. We dated several samples at four differen…
A Preliminary Determination of the Absolute 14 C/ 12 C Ratio of OX-I
A preliminary determination of the absolute 14 C/ 12 C ratio of the oxalic acid I standard (NBS SRM 4990B) has been made. Using an accelerator mass spectrometry (AMS) system, a known number of radiocarbon ions were implanted in a thin copper foil. The foil was then combusted with the addition of 14 C-free carrier material. This resulting gas (which had a known 14 C/ 12 C ratio) was graphitized and compared to OX-I material. This comparison yielde…
Tandem Accelerator Measurements of 10 Be Deposition Rates
A Tandem Van de Graaff accelerator has been modified for use in the direct measurement of natural abundances of 10 Be and 14 C. A description of the system is given and some 10 Be results on oceanographic samples are discussed
Tandem Accelerator Measurements of 10 Be Deposition Rates
A Tandem Van de Graaff accelerator has been modified for use in the direct measurement of natural abundances of 10 Be and 14 C. A description of the system is given and some 10 Be results on oceanographic samples are discussed
Radiocarbon Dating Blood Residues on Prehistoric Stone Tools
We report here the first radiocarbon dating of blood residues on prehistoric stone tools. The residues found on two stone artifacts were subjected to various exploratory biochemical techniques to identify the species from which they were derived and to separate a suitable sample for dating by accelerator mass spectrometry. Although these techniques need much further development and detailed testing, the ages obtained in this first study were cons…
Accelerator Radiocarbon Dating at SFU
The Simon Fraser University accelerator mass spectrometry (AMS) facility has now been in semi-routine use since the beginning of 1985. The advantages and limitations for 14 C dating are described
C Background Levels in An Accelerator Mass Spectrometry System
The levels and sources of the measurement background in an AMS 14 C dating system have been studied in detail. The relative contributions to the total background from combustion, graphitization, storage, handling, and from the accelerator were determined by measuring the C concentrations in samples of anthracite coal ranging in size from 15μg to 20mg. The results show that, for the present system, the uncertainty in the background is greater than…
Improved Collagen Extraction by Modified Longin Method
A re-evaluation of the Longin collagen-extraction method shows that a lower reflux temperature reduces degradation of protein (“collagen”) remnants. This allows additional purification through ultrafiltration to isolate the >30kDalton fraction of the reflux product
Accuracy and Precision in Dating Microgram Carbon Samples
The accuracy of AMS radiocarbon determinations on very small samples has been tested by measuring a suite of microgram-sized samples of a known-age material. The total measurement precision for the smallest sample (50μg) was found to be ± 3% and the precision improved with larger sample size. The accuracies of the measurements were found to be within the measurement precisions
AMS 14C Measurements of Fractionated Soil Organic Matter
14 C measurements are reported for fractionated soil organic matter from a genetic soil sequence which was sampled several times during the period of atmospheric nuclear weapons testing. Fractionation of the soils by density followed by acid hydrolysis was successful in separating the organic matter into components with mean residence times for carbon ranging from 5 to 20 years (low density fraction) to several thousand years (residue after acid …
Ultra-Small Carbon Samples and the Dating of Sediments
Radiocarbon dates from sediment core samples are usually obtained on the whole organic carbon portion in order to use as little of the valuable sediment as possible. Such measurements may not result in an accurate chronology of the sediment because the material may include carbon from different reservoirs at the time of deposition. The development of AMS techniques for dating ultra-small (20–500 μ g) carbon samples permits dating various componen…
Younger Dryas Climatic Reversal in Northeastern USA? AMS Ages for an Old Problem
Late-glacial macrofossils from a 10-m core from Alpine Swamp, New Jersey, were radiocarbon dated using accelerator mass spectrometry (AMS). The arrival of the first trees to the area following deglaciation is indicated by maximum percentages of spruce pollen and a date of 12,290 ± 440 yr B.P. on a single spruce needle. Subsequent spread of deciduous hardwoods was followed by the expansion of boreal taxa, including spruce ( Picea ), fir ( Abies ),…
Memory Effects in an AMS System
A sample with a 14 C concentration estimated to be greater than 30,000 Modern was inadvertently graphitized and measured in an AMS system. No measurable contamination of the cesium sputter ion source was observed. Simple cleaning procedures removed the contamination from the sample preparation system, with the exception of the reaction vessel in which the sample was graphitized. Sample cross-contamination factors were estimated for all of the pre…
Progress in AMS Measurements at the LLNL Spectrometer
We report on the present status of the Lawrence Livermore AMS spectrometer, including sample throughput and progress towards routine 1% measurement capability for 14 C, first results on other isotopes and experience with a multisample high-intensity ion source
Radiocarbon Dates for Beeswax Figures in the Prehistoric Rock Art of Northern Australia
Accelerator mass spectrometry radiocarbon ages have been taken for a test suite of small samples of material removed from some of the ‘beeswax’art figures found in rock shelters in northern Australia. The results indicate that we can reliably date this unique form of rock art with no noticeable damage. We had not expected to find figures of any great antiquity, and so we were surprised to find that the ages obtained spanned the time period from t…
Stepped-Combustion 14 C Dating of Sediment
Radiocarbon dating of bulk sediment has long been used as a method of last resort when reliable wood, charcoal, or plant macrofossils are not available for analysis. Accurate dating of sediment is complicated by the presence of multiple organic carbon fractions, each with a potentially different 14 C activity. Additionally, the presence of carbon bound by clay minerals can significantly reduce the accuracy of a sediment age determination, with th…
Radiocarbon dates for pictographs in Ignatievskaya Cave, Russia
Samples from three charcoal pictographs at Ignatievskaya Cave, in the southern Ural Mountains of Russia, have been radiocarbon dated. An advanced antiquity was expected, with some paintings thought to be more than 10,000 years old, as suggested by the imagery. One charcoal painting, for example, resembles a mammoth. The radiocarbon date of that motif, however, dates only to 7370±50 BP. If that motif actually represents a live mammoth, it places m…
Magnesium Perchlorate as an Alternative Water Trap in AMS Graphite Sample Preparation
We present a brief discussion of sample preparation procedures at the Keck Carbon Cycle Accelerator Mass Spectrometer (KCCAMS), University of California, Irvine, and a systematic investigation of the use of Mg(ClO 4 ) 2 as an absorptive water trap, replacing the standard dry ice/ethanol cold finger in graphite sample preparation. We compare high-precision AMS measurement results from oxalic acid I and USGS coal samples using Mg(ClO 4 ) 2 under di…
NotCal04—Comparison/Calibration 14 C Records 26–50 Cal Kyr BP
The radiocarbon calibration curve IntCal04 extends back to 26 cal kyr B P. While several high-resolution records exist beyond this limit, these data sets exhibit discrepancies of up to several millennia. As a result, no calibration curve for the time range 26–50 cal kyr BP can be recommended as yet, but in this paper the IntCal04 working group compares the available data sets and offers a discussion of the information that they hold
Ion Source Development at Kccams, University of California, Irvine
The Keck Carbon Cycle accelerator mass spectrometry facility at the University of California, Irvine, operates a National Electronics Corporation 40-sample MC-SNICS ion source. We describe modifications that have increased beam current output, improved reliability, and made the source easier to service
Ultra small-mass AMS 14C sample preparation and analyses at KCCAMS/UCI Facility
A Preliminary Determination of the Absolute 14 C/ 12 C Ratio of OX-I
A preliminary determination of the absolute 14 C/ 12 C ratio of the oxalic acid I standard (NBS SRM 4990B) has been made. Using an accelerator mass spectrometry (AMS) system, a known number of radiocarbon ions were implanted in a thin copper foil. The foil was then combusted with the addition of 14 C-free carrier material. This resulting gas (which had a known 14 C/ 12 C ratio) was graphitized and compared to OX-I material. This comparison yielde…
AMS 14 C Sample Preparation at the KCCAMS/UCI Facility
We present an overview of accelerator mass spectrometry (AMS) radiocarbon sample preparation and measurements, describing the technical upgrades that now allow us to routinely obtain 0.2–0.3% precision for 1-mg carbon samples. A precision of ∼1% on samples with 100 μg of carbon can also be achieved. We have also developed graphitization techniques and AMS procedures for ultra-small samples (down to 0.002 mg of carbon). Detailed time series are pr…
IntCal09 and Marine09 Radiocarbon Age Calibration Curves, 0-50,000 Years cal BP
The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the 14 C and calendar timescales as established in 2002. No change was made to the curves…
A Comparison of Cellulose Extraction and ABA Pretreatment Methods for AMS 14 C Dating of Ancient Wood
We have compared accelerator mass spectrometry (AMS) radiocarbon results on wood samples at or near the limit of 14 C dating, pretreated with a standard acid-base-acid (ABA) protocol, with those obtained from cellulose prepared from the same samples by several modifications of the Jayme-Wise cellulose extraction method (Green 1963). These tests were carried out to determine the most efficient way to ensure low backgrounds in 14 C measurements of …
Radiocarbon Dating and Stable Isotopic Analysis of Insect Chitin from the Rancho La Brea Tar Pits, Southern California
This paper presents the first successful methods for accelerator mass spectrometry (AMS) dating of asphalt-impregnated insect chitin from the Rancho La Brea Tar Pits in southern California. A persistent problem with stratigraphic correlation at this site is that asphalt flows are characteristically intermittent and are really discontinuous, which can result in mixing fossils of quite different ages. Direct 14 C dating of specimens circumvents thi…
Radiocarbon Dating and Intercomparison of Some Early Historical Radiocarbon Samples
We performed a new series of measurements on samples that were part of early measurements on radiocarbon ( 14 C) dating made in 1948–1949. Our results show generally good agreement to the data published in 1949–1951, despite vast changes in technology, with only two exceptions where there was a discrepancy in the original studies. Our new measurements give calibrated ages that overlap with the known ages. We dated several samples at four differen…
Radiocarbon dating (19 works) · Chemistry (16 works) · Accelerator mass spectrometry (15 works) · Geology (15 works) · Archaeology and ancient environmental studies (12 works) · Geology and Paleoclimatology Research (12 works) · Isotope Analysis in Ecology (11 works) · Paleontology (11 works) · Archaeology (10 works) · Chromatography (10 works)