• 

  Radiocarbon, Volume 41, Number 3 (1999)

  Department of Geosciences, The University of Arizona, 1999-01-01
• 

  Radiocarbon, Volume 41, Number 1 (1999)

  Department of Geosciences, The University of Arizona, 1999-01-01
• 

  Radiocarbon, Volume 41, Number 2 (1999)

  Department of Geosciences, The University of Arizona, 1999-01-01
• 

  From the Managing Editor

  Sewell, David R. (Department of Geosciences, The University of Arizona, 1999-01-01)
• 

  From the Managing and Associate Managing Editors

  Sewell, David; Elliott, Kimberley (Department of Geosciences, The University of Arizona, 1999-01-01)
• 

  From the Managing Editor

  Sewell, David (Department of Geosciences, The University of Arizona, 1999-01-01)
• 

  From the Editor

  Jull, A. J. T. (Department of Geosciences, The University of Arizona, 1999-01-01)
• 

  From the Editor

  Long, Austin (Department of Geosciences, The University of Arizona, 1999-01-01)
• 

  Editorial Board

  Department of Geosciences, The University of Arizona, 1999-01-01
• 

  Editorial Board

  Department of Geosciences, The University of Arizona, 1999-01-01
• 

  Associate Editors

  Department of Geosciences, The University of Arizona, 1999-01-01
• 

  Variations of Isotopic Composition of Carbon in the Karst Environment from Southern Poland, Present and Past

  Pazdur, Anna; Goslar, Tomasz; Pawlyta, Mirosława; Hercman, Helena; Gradziński, Michał (Department of Geosciences, The University of Arizona, 1999-01-01)

  We describe a comprehensive study of carbon isotopes in several karst springs and their environs in a contemporary karst environment in the region of the Cracow-Wielun Upland and Western Tatra Mountains, Southern Poland. We collected samples of water, plants and carbonate deposited on aquatic plants, and obtained 13C values and 14C concentrations. We also investigated a group of the youngest calcium carbonates from caves where deposition is still being observed or ceased no more than a few hundred years ago. The determination of a 14C dilution factor (q) in these carbonates allows us to determine the "true" radiocarbon ages of old speleothems from caves in the area under investigation and enables the use of old speleothems as suitable material for extending the 14C calibration time scale, the "Absolute" age having been determined by U/Th or amino acid racemization (AAR) dating methods. Measurements of delta-13C and 14C concentrations were made on dissolved inorganic carbon (DIC) extracted from water samples. Calculated values of q range from 0.55 to 0.68 and delta-13C values range from -10 per mil to -13 per mil versus VPDB with mean values equal to 0.65 and -12 per mil, respectively. Results indicate that the dissolution process of limestone bedrock is a closed system with the dominating contributor being biogenic carbon dioxide. Isotopic composition of carbon in contemporary plants collected at the karstic springs at 3 localities is highly diverse, with different species distinctly varying in both q and delta-13C values. Extremely light values of 13C (under -40 per mil), observed in Algae and Hyloconium splendens, are correlated with 14C concentrations that are much lower than 100 pMC. Small systematic changes of isotopic composition were found in plants of the same species collected along streams at various distances from the spring. The youngest calcium carbonates from different caves show a relatively high scatter of both delta-13C values and 14C concentration. The lower reservoir effect for 14C is observed in samples with higher value of delta-13C, indicating equilibrium conditions in the sedimentation of carbonate. Pazdur et al. (1995b) presented 14C dating results and paleoclimatic interpretation of 170 14C analyses of 89 speleothems from 41 caves obtained through 1994. Investigations continued until early 1997, during which time a speleothem, JWi2, was dated by 14C, U/Th and AAR dating methods, and its stable isotope composition (delta-13C and delta-18O) analyzed in detail (reported here). Carbon isotope analyses indicate very large differences among results obtained by U/Th, AAR, and 14C dating methods.
• 

  Use of Radiocarbon Dating in Assessing Christian Connections to the Dead Sea Scrolls

  Rodley, G. A.; Thiering, B. E. (Department of Geosciences, The University of Arizona, 1999-01-01)

  We present an analysis of radiocarbon dates on Dead Sea Scrolls that have a bearing on the question of the Scroll documents' relation to Christian origins. We assess details of dating reports, discuss paleographical evidence, and consider the content of the documents. When collated, these findings may be seen as compatible with a view that personalities mentioned in the Scrolls were contemporary with the founders of Christianity.
• 

  The Spatial and Temporal Patterns of Stick-Nest Rat Middens in Australia

  Pearson, Stuart; Lawson, Ewan; Head, Lesley; McCarthy, Lynne; Dodson, John (Department of Geosciences, The University of Arizona, 1999-01-01)

  The spatial and temporal distribution of 145 radiocarbon dates on 66 Australian stick-nest rat middens (Muridae: Leporillus spp.) range from modern to 10,900 +/90 BP. As in American packrat middens, age frequency follows a logarithmic decay, both continentally and at major sites. This is probably a result of natural decay processes. Unlike American middens of similar age, relatively few range changes in plant distribution have been detected in Australia. The distribution of 14C ages and the associated midden materials provide important paleoenvironmental information from the arid interior of Australia. The middens record subtle changes in vegetation and dramatic changes in the fauna unlike those interpreted from sites on the coastal rim or the southeastern periphery of the arid zone.
• 

  The Maunder Minimum: An Interlaboratory Comparison of Delta-14C from AD 1688 to AD 1710

  Damon, Paul E.; Eastoe, Christopher J.; Mikheeva, Irina B. (Department of Geosciences, The University of Arizona, 1999-01-01)

  Measurements on same-age tree-ring samples from proximal Ural Mountain trees by the Ioffe Institute research group and at the University of Arizona demonstrate a variance corresponding to a standard deviation of +/5.1 per mil for Ioffe compared to +/2.1 per mil for Tucson. There is also a calibration difference of 4.3 +/1.2 sigma per mil. Comparison of the same years measured in Seattle on wood from the Pacific Northwest shows an offset of 2.2 +/0.5 sigma per mil. This is not a calibration error, but rather is expected from the well-documented evidence for divergence and upwelling of 14C-depleted CO2 along the west coast of North America.
• 

  The Reliability of AMS Radiocarbon Dating of Shells from China

  Zhou, Weijian; Head, M. J.; Wang, Fubao; Donahue, D. J.; Jull, A. J. T. (Department of Geosciences, The University of Arizona, 1999-01-01)

  We tested the feasibility of dating freshwater and terrestrial molluscs from the semiarid and arid zone in China, since these types of shell material deposit only aragonite to form their shell structure, and shell integrity can be easily observed using X-ray diffraction. We also tested the possibility of estimating microenvironmental changes from shell delta-13C values, but variations within shell populations preclude the use of these values as a reliable indicator. Reservoir ages were calculated for living shells of the same species as fossil shells by using their measured 14C ages, which were recalculated using an average value of atmospheric 14C activity for the years spanning their time of collection as the modern standard. The results indicate that freshwater and terrestrial shells are potentially useful as dating material, provided extreme care is taken in their collection and other datable material (in this case wood and pollen) is within the profile to act as a comparison.
• 

  Subject Index Volume 41, 1999

  Department of Geosciences, The University of Arizona, 1999-01-01
• 

  Rudjer Bošković Institute Radiocarbon Measurements XIV

  Horvatinčić, Nada; Obelić, Bogomil; Krajcar Bronić, Ines; Srdoč, Dušan; Čalić, Romana (Department of Geosciences, The University of Arizona, 1999-01-01)
• 

  Reporting 14C Activities and Concentrations

  Mook, Willem G.; van der Plicht, Johannes (Department of Geosciences, The University of Arizona, 1999-01-01)

  Three modes of reporting 14C activities are in use, in part analogous to the internationally accepted (IAEA) conventions for stable isotopes: (1) absolute activity, the specific activity of 14C or the activity per gram of carbon; (2) activity ratio, the ratio between the absolute activities of a sample and the standard; and (3) relative activity, the difference between the absolute activities of a sample and standard material, relative to the absolute standard activity. The basic definitions originate from decisions made by the radiocarbon community at its past conferences. Stuiver and Polach (1977) reviewed and sought to specify the definitions and conventions. Several colleagues, however, have experienced inadequacies and pitfalls in the definitions and use of symbols. Furthermore, the latter have to be slightly amended because of the use of modern measuring techniques. This paper is intended to provide a consistent set of reporting symbols and definitions, illustrated by some practical examples.
• 

  Reliability of Bone Gelatin AMS Dating: Rattus exulans and Marine Shell Radiocarbon Dates from Pauatahanui Midden Sites in Wellington, New Zealand

  Athfield, Nancy Beavan; McFadgen, Bruce; Sparks, Rodger (Department of Geosciences, The University of Arizona, 1999-01-01)

  A suite of 6 bone gelatin accelerator mass spectrometry (AMS) radiocarbon dates for Rattus exulans Peale and associated beta decay 14C dates for Austrovenus stutchburyi shell are presented for 4 middens at Pauatahanui, Wellington, New Zealand. Mean calibrated age ranges of Rattus exulans (520-435 BP and 350-330 BP at 95% confidence level) and shell (465-375 BP at 95% confidence level) from the 4 midden sites overlap. The agreement between Rattus exulans bone gelatin dates and associated shell provides an inter-sample comparison of 14C dating using both gas counting (beta decay) and AMS dating techniques. We examine the adequacy of the standard gelatinization treatment for bone samples, which has been employed consistently at the laboratory since 1995.

View more