Miniature radiocarbon measurements ( < 150 µg C) from sediments of Lake Żabińskie, Poland: effect of precision and dating density on age–depth models
Miniature radiocarbon measurements ( < 150 µg C) from sediments of Lake Żabińskie, Poland: effect of precision and dating density on age–depth models
复制标题
波兰扎宾斯基湖沉积物的微型放射性碳测量（< 150 µg C）：精度和测年密度对年龄深度模型的影响
DOI：
10.5194/gchron-2-63-2020
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
M. Grosjean
中科院分区：
文献类型：
--
作者：
P. Zander;S. Szidat;D. Kaufman;Maurycy Żarczyński;Anna I. Poraj;P. Boltshauser;M. Grosjean
Abstract. The recent development of the MIni CArbon DAting System (MICADAS) allows
researchers to obtain radiocarbon (14C) ages from a variety of samples
with miniature amounts of carbon (<150 µg C) by using a gas
ion source input that bypasses the graphitization step used for conventional
14C dating with accelerator mass spectrometry (AMS). The ability to
measure smaller samples, at reduced cost compared with graphitized samples,
allows for greater dating density of sediments with low macrofossil
concentrations. In this study, we use a section of varved sediments from
Lake Żabińskie, NE Poland, as a case study to assess the usefulness
of miniature samples from terrestrial plant macrofossils for dating lake
sediments. Radiocarbon samples analyzed using gas-source techniques were
measured from the same depths as larger graphitized samples to compare the
reliability and precision of the two techniques directly. We find that the
analytical precision of gas-source measurements decreases as sample mass
decreases but is comparable with graphitized samples of a similar size
(approximately 150 µg C). For samples larger than 40 µg C and
younger than 6000 BP, the uncalibrated 1σ age uncertainty is
consistently less than 150 years (±0.010 F14C). The reliability
of 14C ages from both techniques is assessed via comparison with a
best-age estimate for the sediment sequence, which is the result of an OxCal
V sequence that integrates varve counts with 14C ages. No bias is
evident in the ages produced by either gas-source input or graphitization.
None of the 14C ages in our dataset are clear outliers; the 95 %
confidence intervals of all 48 calibrated 14C ages overlap with the
median best-age estimate. The effects of sample mass (which defines the
expected analytical age uncertainty) and dating density on age–depth models
are evaluated via simulated sets of 14C ages that are used as inputs
for OxCal P-sequence age–depth models. Nine different sampling scenarios
were simulated in which the mass of 14C samples and the number of
samples were manipulated. The simulated age–depth models suggest that the
lower analytical precision associated with miniature samples can be
compensated for by increased dating density. The data presented in this
paper can improve sampling strategies and can inform expectations of age
uncertainty from miniature radiocarbon samples as well as age–depth model
outcomes for lacustrine sediments.
剑桥大学戈德温放射性碳实验室用于古海洋学研究的小碳酸盐样品的石墨化
影响因子：
8.3
作者：
Freeman E
通讯作者：
Freeman E