• Packard Instrument Company Radiocarbon Dates I

      Kowalski, Sandra J. (American Journal of Science, 1965-01-01)
    • Packard Instrument Company Radiocarbon Dates II

      Kowalski, Sandra J.; Schrodt, Ariel G. (American Journal of Science, 1966-01-01)
    • Paired 14C and 230Th/U Dating of Surface Corals from the Marquesas and Vanuatu (Sub-Equatorial Pacific) in the 3000 to 15,000 Cal Yr Interval

      Paterne, Martine; Ayliffe, Linda K.; Arnold, Maurice; Cabioch, Guy; Tisnérat-Laborde, Nadine; Edouar, Edouard Bard; Douville, Eric; Bard, Edouard (Department of Geosciences, The University of Arizona, 2004-01-01)
      Paired radiocarbon and 230Th/U dating was performed on 13 surface corals from submerged reefs in the Marquesas and from raised terraces in Vanuatu. The absolute ages of the corals analyzed ranged from 3000 to 15,000 cal yr. Estimates of the difference between the absolute and 14C ages of these corals are in agreement with previous determinations up until 11,500 cal yr. The resulting mean sea surface reservoir age R is determined at 390 +/60 yr for the Marquesas region (9 degrees S), which is slightly higher than the R value at 280 +/50 yr for the Tahiti Islands (18 degrees S). Multiple 14C analyses of 2 corals from the Marquesas present scattered 14C ages at ~12,000 and ~15,100 cal yr. This could be attributed to rapid changes of the 14C content of surface waters around the Marquesas Islands or to a subtle submarine diagenesis.
    • Paired AMS 14C Dates on Planktic Foraminifera from a Gulf of Mexico Sediment Core: An Assessment of Stratigraphic Continuity

      Flower, B. P.; Hastings, D. W.; Randle, N. J. (Department of Geosciences, The University of Arizona, 2011-01-01)
      A series of recent papers has called for multiple radiocarbon dates on planktic foraminifera to assess stratigraphic continuity in deep-sea sediment cores. This recommendation comes from observations of anomalous 14C dates in planktic foraminifera from the same stratigraphic level. Potential reasons include bioturbation, downslope transport, secondary calcification, carbonate dissolution, and differential preservation. In this study, paired 14C dates on dissolution-susceptible Globigerinoides ruber and dissolution-resistant Neogloboquadrina dutertrei are used to evaluate a Gulf of Mexico sediment core. Fourteen of 15 pairs (between 8815 and 12,995 uncorrected 14C yr BP) yield concordant uncorrected 14C ages (mean difference -2 +/- 75 yr), attesting to continuous deposition at high accumulation rates (>35 cm/kyr). For 1 pair, N. dutertrei is nearly 1000 yr younger, which is difficult to explain by any combination of dissolution and bioturbation or downslope transport, given the excellent carbonate preservation and persistent laminations. The concordant ages underscore the utility of paired 14C dates in planktic foraminifera as a means of assessing stratigraphic continuity in deep-sea sediment sequences.
    • Paired Dating of Pith and Outer Edge (Terminus) Samples from Pre-Hispanic Caribbean Wooden Sculptures

      Brock, Fiona; Ostapkowicz, Joanna; Bronk Ramsey, Christopher; Wiedenhoeft, Alex; Cartwright, Caroline (Department of Geosciences, The University of Arizona, 2012-10-15)
      Radiocarbon dating of historical and archaeological wood can be complicated, sometimes involving issues of “inbuilt” age in slow-growing woods, and/or the possibility of reuse or long delays between felling and use of the wood. Terminus dates can be provided by dating the sapwood, or the outermost edge of heartwood, while a date from the pith can give an indication of the first years of growth. A sequence of samples from specific points within the bole can be used to determine the growth rate of the tree. Such a combined dating strategy is particularly useful in cross-referencing dates from a single piece, better placing it in its chronological context. This paper reports paired or multiple dates from 11 wooden sculptures dated as part of the Pre-Hispanic Caribbean Sculptural Arts in Wood project, which studied 66 wooden artifacts attributed to the pre-colonial Taíno, the indigenous peoples of the Caribbean’s Greater Antilles. The calibrated ages of the pieces published here range from ~AD 700–1500, indicating that the Taíno were producing elaborate sculptures much earlier than previously thought. The paired or multiple dates from these carvings confirmed the accuracy of the results, and were also used to construct a growth rate model of what was expected to be a slow-growing species (Guaiacum sp.). This model demonstrates that the boles used to create the sculptures grew on average 1 cm every 6–13 yr.
    • Palaeosols Within Loess: Dating Palaeoclimatic Events in Kashmir

      Kusumgar, Sheela; Agrawal, D. P.; Juyal, Navin; Sharma, Prabhakar (American Journal of Science, 1986-01-01)
      The 14C dates of Kashmir loess-palaeosols form five clusters. The dates, mineral magnetic, stable isotopic, and pollen data help decipher major climatic oscillations as distinct from the minor ones.
    • Paleoclimatic Evidence in Apparent 14C Ages of Saharian Groundwaters

      Sonntag, Christian; Thorweihe, Ulf; Rudolph, Jochen; Löhnert, E. P.; Junghans, Christel; Münnich, K. O.; Klitzsch, Eberhard; El Shazly, E. M.; Swailem, F. M. (American Journal of Science, 1980-01-01)
      Frequency distributions of more than 300 14C groundwater ages from various regions in northern and southern Sahara reflect the alternating sequence of humid and arid periods in the Sahara during the Holocene and late Pleistocene. A broad frequency maximum between 20,000 and 50,000 years BP indicates a long humid period. During this time span, the northern Sahara received rain from the Western Drift, which is concluded from a west-east decrease of deuterium and oxygen 18 of these groundwaters (continental effect). In the time-slice between 14,000 and 20,000 years BP, groundwater formation was significantly lower due to a cool and (semi-)arid period. In the Holocene, the Saharian climate is characterized by a sequence of dry and wet periods.
    • Paleoclimatic Implications of Radiocarbon Dating of Speleothems from the Cracow-Wieluń Upland, Southern Poland

      Pazdur, Anna; Pazdur, Mieczysław F.; Pawlyta, Jacek; Górny, Andrzej; Olszewski, Michał (Department of Geosciences, The University of Arizona, 1995-01-01)
      We report preliminary results of a long-term systematic study intended to gather paleoclimatic records from precisely dated speleothems. The research project is limited to speleothems deposited in caves of the Cracow-Wieluń Upland, the largest and best-explored karst region in Poland, covering ca. 2900 km2 with >1000 caves. Speleothem samples were selected from collections of the Geological Museum of the Academy of Mining and Metallurgy in Cracow. Radiocarbon dates of these samples from ca. 45-20 ka BP almost exactly coincide with age range of the Interplenivistulian. A break in speleothem formation between ca. 20 and 10 ka BP may be interpreted as a result of serious climatic deterioration associated with the maximum extent of the last glaciation. We observed differences among 14C, U/Th and AAR dating results. Changes of delta-13C and delta-18O in speleothems that grew between ca. 30 and 20 ka BP may be interpreted as changes of paleoclimatic conditions.
    • Paleodiet Reconstruction of Human Remains from the Archaeological Site of Natfieh, Northern Jordan

      Al-Bashaireh, K.; Al-Shorman, A.; Rose, J.; Jull, A. J. T.; Hodgins, G. (Department of Geosciences, The University of Arizona, 2010-01-01)
      This investigation concerns human teeth and bones from the site of Natfieh, north Jordan. Nitrogen and carbon isotope analyses were used to model the paleo-economy by reconstructing Natfieh's paleodiet during a specific time period. 14C dating of human teeth and bones from the site of Natfieh, north Jordan, demonstrate that they belong to the Early Roman period and match the archaeological date from the tomb and grave goods typology. Stable isotope analyses of these humans have provided new information about the subsistence and society of individuals buried at Natfieh. Natfieh is today agriculturally productive and must have been so in antiquity with most of the foodstuffs having been produced locally. The long distance between Natfieh and the closest aquatic food source (Mediterranean Sea and Lake Tiberias) and the high cost of land transportation might be the reason for the low consumption of marine protein. The results agree with past research on the Roman diet showing that plants were the common source of food for the Romans and fish may have been restricted to elite members of the society.
    • Paleoearthquakes as Anchor Points in Bayesian Radiocarbon Deposition Models: A Case Study from the Dead Sea

      Kagan, Elisa J.; Stein, Mordechai; Agnon, Amotz; Ramsey, Christopher Bronk (Department of Geosciences, The University of Arizona, 2010-01-01)
      The Bayesian statistical method of the OxCal v 4.1 program is used to construct an age-depth model for a set of accelerator mass spectrometry (AMS) radiocarbon ages of organic debris collected from a late Holocene Dead Sea stratigraphic section (the Ein Feshkha Nature Reserve). The model is tested for a case where no prior earthquake information is applied and for a case where there is incorporation of known ages of 4 prominent historical earthquakes as chronological anchor points along the section. While the anchor-based model provided a tightly constrained age-depth regression, the "non-anchored" model still produces a correlation where most of the 68% or 95% age ranges of the 52 seismites can be correlated to historical earthquakes. This presents us with the opportunity for high-resolution paleoseismic analysis and comparison between various sites.
    • Paleoecology, Subsistence, and 14C Chronology of the Eurasian Caspian Steppe Bronze Age

      Shishlina, N. I.; Zazovskaya, E. P.; van der Plicht, J.; Hedges, R. E. M.; Sevastyanov, V. S.; Chicagova, O. A. (Department of Geosciences, The University of Arizona, 2009-01-01)
      Combined analysis of paleoenvironment, 13C, 15N, and 14C in bone, including paired dating of human bone and terrestrial materials (herbivore bone, wood, charcoal, and textile) has been performed on many samples excavated from Russian kurgan graves. The data can be used for dietary reconstruction, and reservoir corrections for 14C dating of human bone. The latter is essential for an accurate construction of chronologies for the Eneolithic and Bronze Age cultures of the Caspian steppes.
    • Paleoenvironment in Dae-Am San High Moor in the Korean Peninsula

      Yoshioka, T.; Lee, J. Y.; Takahashi, H. A.; Kang, S. J. (Department of Geosciences, The University of Arizona, 2001-01-01)
      We discuss paleoenvironmental changes at the Dae-Am San high moor, located near the Demilitarized Zone at 38 degrees N. This area has been reported to be the only high moor in the Korean peninsula. The 14C age of the bottom sediment (75-80 cm in depth) at this site is about 1900 BP. Since the radiocarbon ages for the intervals at 50-55 cm and 75-80 cm were almost the same, we conclude that the deep layers (55-80 cm) in the high moor were all part of the original soil. Low organic C and N contents in the deeper layers support this inference. The 50-55 cm layer consists of sandy material with very low organic content, suggesting erosion from the surrounding area. The surface layer (0-5 cm) was measured as 190 BP, and the middle layer (30-35 cm) was 870 BP. The bulk sedimentation rate was estimated to be about 0.4 mm yr-1 for the 0-30-cm interval. The delta-13C value of organic carbon in the sediments fluctuated with depth. The delta-13C profile of the Dae-Am San high moor may be explained by climatic changes which occurred during the Little Ice Age and Medieval Warm Period.
    • Paleoenvironment of Medieval Archaeological Sites in Central Japan: Assemblage Analysis and 14C Dating of Insect Fossils

      Okuno, E.; Mori, Y.; Nakamura, T. (Department of Geosciences, The University of Arizona, 2010-01-01)
      This study aimed to investigate the paleoenvironment of 2 Medieval archaeological sites, Onigashioya and Ooke, in central Japan, by assemblage analyses of insect fossils preserved in sediments at the sites. In the Onigashioya site located in Mie Prefecture, the sclerites of insect fossils classified as the "village" type were detected, which indicates that human activities, and in particular farming, were taking place there. Rice paddies and fields existed near the site, which explains why many insects harmful to rice plants and crops were detected in the area. The radiocarbon date for sclerite remains of Hydrophilus acuminatus, an aquatic beetle that live in rice paddy fields, was calibrated to be cal AD 1010-1155. Analysis of sclerite remains of Craspedonotus tibialis, a ground beetle that typically inhabits seashore environments, resulted in a date of cal AD 1020-1155. This finding suggests that human settlements existed in the seaside areas of the Onigashioya site in the 11th century AD. In the Ooke site located in Aichi Prefecture, "insect pits" were found, which are structural remains containing a large number of Anomala rufocuprea, an insect that preys on field crops. Farmers would have gathered the insects from the fields and buried the dead remains in the pits. Accelerator mass spectrometry (AMS) 14C dates on sclerite remains of A. rufocuprea ranged from cal AD 1264 to 1385. It should be noted that fruit trees and vegetable crops were planted widely around the site in the 13th century AD. As the result, A. rufocuprea propagated greatly around the site in that period. It is probable that many insects harmful to field crops multiplied largely in this region due to the development of local woods and plains into farming fields. This type of development occurred throughout Japan during the Medieval period.
    • Paleogroundwater in the Moutere Gravel Aquifers Near Nelson, New Zealand

      Stewart, Michael K.; Thomas, Joseph T.; Norris, Margaret; Trompetter, Vanessa (Department of Geosciences, The University of Arizona, 2004-01-01)
      Radiocarbon, 18O, and chemical concentrations have been used to identify groundwater recharged during the last ice age near Nelson, New Zealand. Moutere Gravel underlies most of the Moutere Depression, a 30-km-wide system of valleys filled with Plio-Pleistocene gravel. The depression extends northwards into Tasman Bay, which was above sea level when the North and South Islands of New Zealand were connected during the last glaciation. The aquifers are tapped by bores up to 500 m deep. Shallow bores (50-100m) tap "pre-industrial" Holocene water (termed the "modern" component) with 14C concentrations of 90 +/10 percent modern carbon (pMC) and delta-18O values of -6.8 +/0.4 per mil, as expected for present-day precipitation. Deeper bores discharge water with lower 14C concentrations and more negative 18O values resulting from input of much older water from depth. The deep end-member of the mixing trend is identified as paleowater (termed the "glacial" component) with 14C concentration close to 0 pMC and more negative 18O values (-7.6 per mil). Mixing of the modern and glacial components gives rise to the variations observed in the 14C, 18O, and chemical concentrations of the waters. Identification of the deep groundwater as glacial water suggests that there may be a large body of such water onshore and offshore at deep levels. More generally, the influence of changing sea levels in the recent past (geologically speaking) on the disposition of groundwaters in coastal areas of New Zealand may have been far greater than we have previously realized.
    • Paleoproductivity Variations in the Equatorial Arabian Sea: Implications for East African and Indian Summer Rainfalls and the El Niño Frequency

      Tiwari, Manish; Ramesh, Rengaswamy; Bhushan, Ravi; Somayajulu, B. L. K.; Jull, A. J. Timothy; Burr, George S. (Department of Geosciences, The University of Arizona, 2006-01-01)
      We analyzed a sediment core from the equatorial Arabian Sea, chronologically constrained by accurate accelerator mass spectrometry (AMS) radiocarbon dates on selected planktonic foraminiferal species, for paleoproductivity variations corresponding to the variations in the Indian Ocean Equatorial Westerlies (IEW). The IEW in turn are positively correlated to the Southern Oscillation Index (SOI), which is a measure of El Nio, Southwest monsoon (SWM), and east African rainfall (EAR). The productivity data show that Indian and east African rainfalls declined from 35,000 calendar yr BP up to the last glacial maximum (LGM), with the maximum El Nio frequency during the last glacial period. From ~14,500 to ~2000 calendar yr BP (i.e. Core top), we find strengthening SWM and EAR along with declining El Nio frequency.
    • Palynological and Sedimentological Evidence for a Radiocarbon Chronology of Environmental Change and Polynesian Deforestation from Lake Taumatawhana, Northland, New Zealand.

      Elliot, M. B.; Striewski, B.; Flenley, J. R.; Sutton, D. G. (Department of Geosciences, The University of Arizona, 1995-01-01)
      We present pollen diagrams and sedimentological analyses from a lake site within an extensive dune system on the Aupouri Peninsula, Northland. Five thousand years ago, a regional Agathis australis — podocarp-broadleaf forest dominated the vegetation, which manifested an increasing preponderance of conifer species. Climate was cooler and drier than at present. From ca. 3400 BP, warmth-loving species such as A. Australis and drought-intolerant species, Dacrydium cupressinum and Ascarina lucida, became common, implying a warm and moist climate. The pollen record also suggests a windier climate. The most significant event in the record, however, occurred after ca. 900 BP (800 cal BP) when anthropogenic deforestation commenced. A dramatic decline in forest taxa followed, accompanied by the establishment of a Pteridium-esculentum-dominated community. Fire almost certainly caused this, evidenced by a dramatic increase of charcoal. Sedimentological evidence for this site indicates a relatively stable environment before humans arrived and an increasingly unstable environment with frequent erosional events after human contact.
    • Parameters of a Radiocarbon Installation

      Khait, Vladimir Z. (Department of Geosciences, The University of Arizona, 1996-01-01)
      I aim to define instrumental parameters of a radiocarbon laboratory installation whereby one can estimate its precision and a maximum age up to which its measuring results are reliable. The commonly accepted factor of merit (FM) relates the precision of measurement to Poisson statistics. Unlike the FM, the proposed parameters show the extent to which a 14C laboratory is affected by destabilizing factors that could cause additional measurement errors. Assuming that all destabilizing factors produce either a change in counting efficiency or additional fluctuations of the background counting rate, I have derived two parameters for consideration.
    • Part 2: The Third International Radiocarbon Intercomparison (TIRI)

      Scott, E. M. (Department of Geosciences, The University of Arizona, 2003-01-01)
    • Participants

      American Journal of Science, 1983-01-01
    • Participants

      Department of Geosciences, The University of Arizona, 1992-01-01