http://hdl.handle.net/10150/635079 2026-05-20T13:57:32Z 2026-05-20T13:57:32Z Jull, A. J. Timothy http://hdl.handle.net/10150/655160 2021-02-18T02:17:54Z 2007-01-01T00:00:00Z

From the Editor Jull, A. J. Timothy

2007-01-01T00:00:00Z Shah, Sunita R. Pearson, Ann http://hdl.handle.net/10150/653777 2021-02-12T01:33:27Z 2007-01-01T00:00:00Z

Ultra-Microscale (5-25 μg C) Analysis of Individual Lipids by 14C AMS: Assessment and Correction for Sample Processing Blanks Shah, Sunita R.; Pearson, Ann Measurements of the natural abundance of radiocarbon in biomarker molecules can be used to elucidate the biogeochemical roles of marine bacteria and archaea in the oceanic water column. However, the relatively low concentration of biomass, especially below the euphotic zone, inevitably results in small sample sizes for compound-specific analyses. In ultra-microscale 14C measurements, which we define as measurements on samples smaller than 25g C, the process of isolating pure compounds and preparing them for measurement adds significant background carbon. This additional blank carbon can contribute up to 40% of the total sample mass; therefore, it is necessary to quantify all components of the processing blank in order to make appropriate corrections. Complete propagation of error is critical in order to report the correct analytical uncertainty. The carbon blank is composed of at least 3 different sources: i) those that scale in proportion to the mass of the sample; ii) sources that contribute a constant mass of blank, e.g. closed-tube combustion; and iii) contaminants from vacuum lines and/or other aspects of sample handling that are difficult to quantify. We approached the problem of correcting for the total sample processing blank by deriving a 4-part isotopic mass balance based on separating the 3 exogenous components from the sample. Subsequently, we derived the appropriate equations for the full propagation of error associated with these corrections. Equations for these terms are presented. Full treatment of a set of raw data is demonstrated using compound-specific 14C data from the North Central Pacific water column.

2007-01-01T00:00:00Z Jones, Martin Petchey, Fiona Green, Roger Sheppard, Peter Phelan, Matthew http://hdl.handle.net/10150/653762 2021-02-12T01:21:33Z 2007-01-01T00:00:00Z

The Marine ΔR for Nenumbo (Solomon Islands): A Case Study in Calculating Reservoir Offsets from Paired Sample Data Jones, Martin; Petchey, Fiona; Green, Roger; Sheppard, Peter; Phelan, Matthew It is necessary to calculate location-specific marine Delta-R values in order to calibrate marine samples using calibration curves such as those provided through the IntCal98 (Stuiver et al. 1998) data. Where known-age samples are available, this calculation is straightforward (i.e. Stuiver et al. 1986). In the case that a paired marine/terrestrial sample calculation is performed, however, the standard calculation (i.e. Stuiver and Braziunas 1993) requires that the samples are treated as relating to isochronous events. This may not be an appropriate assumption for many archaeological paired samples. In this paper, we present an approach to calculating marine Delta-R values that does not require the dated events to be treated as isochronous. When archaeological evidence allows the dated events to be tightly temporally constrained, the approach presented here and that described by Stuiver and Braziunas (1993) give very similar results. However, where tight temporal constraints are less certain, the 2 approaches can give rise to differing results. The example analysis considered here shows that a Delta-R of 81 +/- 64 14C yr is appropriate for samples in the vicinity of Nenumbo (Reef Islands, southeast Solomon Islands) around the period 2000-3000 BP.

2007-01-01T00:00:00Z Sharon, Ilan Gilboa, Ayelet Jull, A. J. Timothy Boaretto, Elisabetta http://hdl.handle.net/10150/653723 2021-02-18T01:36:37Z 2007-01-01T00:00:00Z

Report on the First Stage of the Iron Age Dating Project in Israel: Supporting a Low Chronology Sharon, Ilan; Gilboa, Ayelet; Jull, A. J. Timothy; Boaretto, Elisabetta The traditional chronology of ancient Israel in the 11th-9th centuries BCE was constructed mainly by correlating archaeological phenomena with biblical narratives and with Bible-derived chronology. The chronology of Cyprus and Greece, and hence of points further west, are in turn based on that of the Levant. Thus, a newly proposed chronology, about 75100 yr lower than the conventional one, bears crucial implications not only for biblical history and historiography but also for cultural processes around the Mediterranean. A comprehensive radiocarbon program was initiated to try and resolve this dilemma. It involves several hundreds of measurements from 21 sites in Israel. Creating the extensive databases necessary for the resolution of tight chronological problems typical of historical periods involves issues of quality control, statistical treatment, modeling, and robustness analysis. The results of the first phase of the dating program favor the new, lower chronology.

2007-01-01T00:00:00Z