• Coral Reef Evolution at the Leeward Side of Ishigaki Island, Southwest Japan

      Yamano, Hiroya; Abe, Osamu; Kitagawa, Hiroyuki; Niu, Etsuko; Nakamura, Toshio (Department of Geosciences, The University of Arizona, 2001-01-01)
      In comparison with windward coral reefs, the facies and evolution of leeward coral reefs has been discussed to a lesser extent. By accelerator mass spectrometry (AMS) carbon-14 dating of coral specimens collected from the trench excavated across a modern coral reef during a fishery port repair, we revealed the internal facies and Holocene evolution of a leeward reef in Ishigaki Island, Ryukyu Island, southwest Japan. The reef facies can be split into three facies: the tabular Acropora reworked facies first formed a ridge by 3500 BP. Then, the tabular Acropora framework facies grew both upward and seaward. The accumulation rates of the tabular Acropora framework facies ranged from 2.2 to 8.3 m/ka. Thus, the reef framework facies and accumulation rates of this leeward reef is similar to those of windward reefs, although the age of the reef top is younger than that of windward reefs.
    • Radiocarbon Ages of Beach Rocks and Late Holocene Sea-Level Changes in the Southern Part of the Nansei Islands, Southwest of Japan

      Omoto, Kunio (Department of Geosciences, The University of Arizona, 2001-01-01)
      Beach rock is a good indicator of the past sea levels, as it is considered to have been formed within the range of intertidal zone. Radiocarbon dates of beach rocks collected from Iriomote Island, Ishigaki Island, and Miyako Island, in the southern part of the Nansei Islands, indicate that the beach rocks were formed between around 4000 BP and 400 BP. Late Holocene sea-level changes were revealed based on the elevations and 14C dates of the beach rocks. The results indicate that the sea level was similar to the present one for at least the past 4000 BP. Isotopic fractionations (delta-13C) of the beach rocks were between +9.4 per mil and -0.8 per mil, suggesting a different origin for calcium carbonate.
    • Radiocarbon Dating of delta-18O-delta-D Plots in Late Pleistocene Ice-Wedges of the Duvanny Yar (Lower Kolyma River, Northern Yakutia)

      Vasil'chuk, Y. K.; Vasil'chuk, A. C.; Rank, Dieter; Kutschera, Walter; Kim, Jong-Chan (Department of Geosciences, The University of Arizona, 2001-01-01)
      The Duvanny Yar cross-section located in the Lower Kolyma River valley of Northern Yakutia (69 degrees N, 158 degrees E, height above the Kolyma River level 55 m), has been studied and dated in detail by radiocarbon. The sequence mainly consists of sandy loam sediments with large syngenetic ice wedges. Their width at the top is 1-3.5 m. Allochthonous organic material occurs in high content, concentrating as 0.5-0.7 m lenses. Shrub fragments, twigs, and mammoth bones are accumulated in peaty layers. Through interpolation based on a series of 14C dates, dating of the host sediments provides an approximate age for the ice wedges. The 14C dates of various types of organic material are sometimes very close, but not all in agreement. Therefore, the dates do not accurately show the age of the delta-18O and delta-D plots. A new approach is developed to a 14C dating strategy of syncryogenic sediments with high admixture of allochthonous organic material. The main purpose of this study is to consider detection of inversions or disturbances in the syngenetic permafrost sediment at the Duvanny Yar cross-section by 14C date series. Direct accelerator mass spectrometry (AMS) dating of the ice confirmed the relatively young age of ice wedges.
    • Radiocarbon Dating of Charred Residues on the Earliest Pottery in Japan

      Nakamura, Toshio; Taniguchi, Yasuhiro; Tsuji, Sei Ichiro; Oda, Hirotaka (Department of Geosciences, The University of Arizona, 2001-01-01)
      Recently, primitive-type pottery was discovered in the Russian Far East, China, and Japan. Radiocarbon ages of far earlier than 10,000 BP have been obtained, relating directly or indirectly to the pottery. As an example of these very old 14C ages for incipient pottery, we report here 14C ages of charred adhesions on five potsherds and three charred wood fragments that were collected with the archeological artifacts (stone tools from the Chojakubo Culture) in the loam layers at the Odai Yamamoto I site (41 degrees 03'44"N, 140 degrees 033'20"E) in Aomori prefecture, at the northern end of the Japanese main island. The carbonaceous remains on the surface of the potsherds could be ancient food residues or soot from fuel for cooking. These small carbon samples were dated at the Tandetron accelerator mass spectrometry (AMS) 14C dating facility at Nagoya University, as well as by Beta Analytic Co. Ltd. Except for two charred wood 14C dates, 7070 +/40 and 7710 +/40 BP, all five charred-residue samples and one wood charcoal sample gave older 14C ages of 12,680-13,780 BP, corresponding to the period of the Chojakubo Culture in Japan. This culture marks the beginning of the Jomon Culture, which is characterized by pottery usage and bow-and-arrow hunting.
    • Radiocarbon Dating of the Human Occupation of Australia Prior to 40 ka BP: Successes and Pitfalls

      Fifield, L. K.; Bird, M. I.; Turney, C. S. M.; Hausladen, P. A.; Santos, G. M.; di Tada, M. L. (Department of Geosciences, The University of Arizona, 2001-01-01)
      Charcoal samples from ancient human occupation sites in Australia have been subjected to a rigorous pretreatment and stepped combustion regime in order to explore the possibility that these sites may be older than previous radiocarbon dating had suggested. In one case, the Devil's Lair site in southwest Australia, the methodology has clearly removed vestiges of contamination by more modern carbon and has led to a revised radiocarbon chronology that provides evidence for human occupation of southwest Australia by at least 44 ka BP and probably by 46-47 ka BP. In contrast, charcoal from the Nauwalabila site has been so severely altered that insufficient of the original carbon remains for reliable 14C dating. Finally, where the charcoal is well preserved, such as at the Carpenter's Gap site, the new results provide reassurance that earlier 14C results of approximately 40 ka BP are indeed true ages and are not simply at the limit of the 14C technique.
    • Balance and Behavior of Carbon Dioxide at an Urban Forest Inferred from the Isotopic and Meteorological Approaches

      Takahashi, Hiroshi Aoki; Hiyama, Tetsuya; Konohira, Eiichi; Takahashi, Atsuhiro; Yoshida, Naohiro; Nakamura, Toshio (Department of Geosciences, The University of Arizona, 2001-01-01)
      Diurnal variations in δ14C, delta-13C and the concentration of atmospheric carbon dioxide in an urban forest were measured on 9 February 1999 to discriminate and quantify contributions from different CO2 sources. The biogenic CO2 concentration remained relatively constant throughout the day. However, anthropogenic CO2 concentration fluctuated with the atmospheric CO2 concentration, and seemed to be controlled by wind velocity and the amount of exhaust gases from fossil fuel burning. The vertical profiles of anthropogenic, biogenic, and total CO2 showed a constant concentration within forest during daytime because of the large vertical CO2 influx, strong winds, and neutral atmospheric condition. The biogenic contribution at night decreased from the forest floor upwards with a smooth gradient, while the anthropogenic contribution showed a direct mirror because of the location of respective CO2 sources—the vertical gradient of wind velocity and the horizontal CO2 supply
    • The Varying Radiocarbon Activity of Some Recent Submerged Estonian Plants Grown in the Early 1990s

      Olsson, Ingrid U.; Kaup, Enn (Department of Geosciences, The University of Arizona, 2001-01-01)
      Eleven samples of aquatic plants from three Estonian lakes were analyzed for their radiocarbon content in a collaboration between the laboratories in Tallinn and Uppsala. delta-13C values for the actual species were compiled to allow normalization of activities measured in Tallinn without delta-13C values. The range for well determined species is usually a few per mil and the statistical uncertainty greater than or equal to 1 per mil delta-13C values vary considerably for different Potamogeton species and Myriophyllum spp. Lake Antu Sinijarv and Lake Päidre are hard-water lakes containing 300 and 200 mg HCO3-/L, respectively. One sample consisted of a carbonate crust deposited on a Ceratophyllum demersum plant in L. Antu Sinijarv. Its Delta-14C value was -147.3 +/6.7 per mil in 1990, whereas the plant had a value of -74.1 +/8.0 per mil (delta-13C = -35.0 per mil). The same species in L. Päidre had a Delta-14C value of +8.0 +/8.8 per mil (delta-13C = -25.2 per mil) in 1992. Other species in L. Päidre contained more 14C, from a Delta-14C value of about +30 per mil to about +155 per mil, the latter value measured in Tallinn on floating leaves of Nuphar lutea, close to that of the contemporaneous atmospheric CO2. In the third lake, Lake Punso, containing >30 mg HCO3-/L, the stems of Nuphar lutea exhibited in 1990 a memory effect: the activity, Delta-14C = 209.6 +/10.3 per mil, significantly exceeded that of the contemporaneous atmospheric CO2. However, the floating leaves of the same plant had the Delta-14C value 143.1 +/10.0 per mil, close to the atmospheric 14C level in 1990. The memory is explained by nutrients stored in the root stock, used when the growth starts.
    • Can We Use Cosmogenic Isotopes to Date Stone Artifacts?

      Ivy-Ochs, Susan; Wüst, Raphael; Kubik, Peter W.; Müller-Beck, Hansjürgen; Schlüchter, Christian (Department of Geosciences, The University of Arizona, 2001-01-01)
      Two chert artifacts from the region near Luxor, Egypt have yielded concentrations of cosmogenic 10Be that allow calculation of nominal exposure ages of 326,000 and 304,000 years. Both artifacts are flakes that were collected atop limestone benches of the Eocene Thebes Formation which form cliffs along the west side of the Nile. The site is at elevation 240 m and is about 15 km from the Nile. Tools associated with these artifacts can be attributed to the Late Acheulean or early Middle Paleolithic (the transition has been suggested to have been on the order of 250,000-300,000 years ago). This area, where abundant chert nodules have weathered out, has been a collection, extraction, and fabrication site since the Early Paleolithic (since at least 400,000 years ago). Surface exposure dating records all periods of exposure. That means these ages represent composite ages, comprised of exposures both before and after working. But what fraction of the 10Be concentration we have measured was acquired before the flakes were produced? Here we propose several approaches to deconvolute the different exposure periods and better approximate the real age of the artifacts. As there is no a priori reason that the two ages should agree with the typological ages of the artifacts, nor for the two independent ages to agree, these first results are especially exciting and intriguing.
    • The Kennewick Skeleton: Chronological and Biomolecular Contexts

      Taylor, R. E.; Smith, David Glenn; Southon, John R. (Department of Geosciences, The University of Arizona, 2001-01-01)
      A human skeleton recovered near Kennewick, Washington, USA in 1996 has been dated to the early Holocene on the basis of multiple radiocarbon determinations, an analysis of a style of a temporally diagnostic projectile point found embedded in the ilium of the skeleton, and geological investigations of the locality where the skeleton was recovered. Based on morphological criteria, the Kennewick skeleton, which is one of the most complete early Holocene human skeletons recovered so far in the Western Hemisphere, appears to be more similar to those of modern South Asians and Europeans than to modern Native Americans or to contemporary indigenous populations of Northeast Asia.
    • Changes of 14C Concentration in Modern Trees from Upper Silesia Region, Poland

      Rakowski, Andrzej Z.; Pawelczyk, Slawomica; Pazdur, Anna (Department of Geosciences, The University of Arizona, 2001-01-01)
      Radiocarbon concentration measurements in tree rings from Upper Silesia indicate significantly lower 14C concentration as compared to the concentrations occurring in “clean air” areas. This phenomenon is known as the Suess effect and is caused by contamination with inactive carbon that originates from fossil fuels combustion. This effect is observed in large urban and industrial areas. Samples for the measurements presented in the paper were collected in some of the largest cities in Upper Silesia: Gliwice, Ruda Śląska, and Chorzów. The samples were annual tree rings (Populus nigra, Pinus silvestris) covering years 1965–1992 and the atmospheric CO2 collected weekly between December 1994 and December 1995.
    • Spatial Variations of Radiocarbon in the Coastal Aquifer of Israel—Indicators of Open and Closed Systems

      Bruce, Debbie; Friedman, Gerald M.; Kaufman, Aaron; Yechieli, Yoseph (Department of Geosciences, The University of Arizona, 2001-01-01)
      The spatial variation in radiocarbon concentration was studied in the Coastal Aquifer of Israel. Lower concentrations were found in the western section of the aquifer (55-70 pMC) as compared to the eastern section (80-100 pMC). Since no correlation was found between the tritium and radiocarbon values, these variations could not simply be explained by a difference in ages, or by a difference in the degree of old calcite dissolution as similar delta-13C values were found throughout the aquifer. The results are best explained when viewing the differences in 14C values within the same coastal aquifer, where the eastern section of the aquifer is a more open system and the western section is a more closed system. In general, the age of the groundwater in the coastal aquifer was found to be less than 50 years old (14C>55 and measurable tritium).
    • The Source of the Yarkon Springs, Israel

      Avisar, D.; Kronfeld, J.; Kolton, J.; Rosenthal, E.; Weinberger, G. (Department of Geosciences, The University of Arizona, 2001-01-01)
      Radiocarbon and tritium analyses are used to show that the accepted conceptual hydrological model of the Yarkon-Taninim aquifer is untenable. The conventional model would have the groundwater flow in the carbonate Judea Group aquifer from the Beer Sheva region in the south to discharge at the Yarkon springs. Moreover, the conventional model considers the Judea Group aquifer to be a single hydrological entity. However, analysis of the Yarkon springs and surrounding wells demonstrate that it is stratified into upper and lower aquifers. The water in the deeper aquifer is fresher, cooler and younger compared to the water in the overlying aquifer. The deeper aquifer water type is identical in composition to the Ca-Mg-HCO3 Judean Hills recharge water immediately to the east. It is this recharge water that is dominant at the Yarkon Springs. There appears to be no derived appreciable contribution of groundwater from the Beersheva region in the south. Thus the currently accepted hydrologic model is in need of serious revision. The present study introduces new and high quality groundwater resources to be target for exploitation.
    • The Site of Verrebroek 'Dok' and its Contribution to the Absolute Dating of the Mesolithic in the Low Countries

      Van Strydonck, Mark J. Y.; Crombé, Philippe; Maes, Ann (Department of Geosciences, The University of Arizona, 2001-01-01)
      The wetland site of Verrebroek “Dok” situated in northern Belgium is one of the largest and best dated locations of Mesolithic material in northwestern Europe. Salvage excavations organized since 1992 at this large, unstratified open-air settlement have revealed more than 50 spatially independent artifact concentrations with traces of numerous fireplaces. Single entity dating of charred hazelnut shells from surface-hearths and charcoal from hearth-pits was used to obtain information not only on the sites duration, but also on the relation between the surface hearths and the hearth-pits. The dates were also used to look at discrepancies between the radiocarbon chronology and the typo-chronology of the lithic artifacts.
    • Calibration of Lacustrine Sediment Ages Using the Relationship between 14C Levels in Lake Waters and in the Atmosphere: The Case of Lake Kinneret

      Stiller, Mariana; Kaufman, Aaron; Carmi, Israel; Mintz, Genia (Department of Geosciences, The University of Arizona, 2001-01-01)
      The source of endogenic organic and inorganic carbon in lacustrine sediments is the dissolved inorganic carbon (DIC) in the lake water. The relation between the radiocarbon levels of DIC in Lake Kinneret and of CO2 in the atmosphere has been investigated. The ratio of the former to the latter was found to be 0.814 +/0.013. This ratio is used for calibrating the age of the sediment according to the natural fluctuations in the atmospheric levels of 14C that occurred during the past 10,000 years.
    • Transport of Sellafield-Derived 14C from the Irish Sea Through the North Channel

      Gulliver, Pauline; Cook, Gordon T.; MacKenzie, Angus B.; Naysmith, Philip; Anderson, Robe (Department of Geosciences, The University of Arizona, 2001-01-01)
      Since the early 1950s, the Sellafield nuclear fuel reprocessing plant in Northwest England has released radiocarbon into the Irish Sea in a mainly inorganic form as part of its authorized liquid effluent discharge. In contrast to the trend in which the activities of most radionuclides in the Sellafield liquid effluent have decreased substantially, 14C discharges have increased since 1994–95. This has largely been due to a policy change favoring marine discharges over atmospheric discharges. 14C is radiologically important due to its long half life, mobility in the environment, and propensity for entering the food chain. Current models for radionuclide dispersal in the Irish Sea are based on a reversible equilibrium distribution coefficient (kd), an approach which has been shown to be inadequate for 14C. Development of predictive models for the fate of Sellafield-derived 14C requires a thorough understanding of the biogeochemical fluxes between different carbon reservoirs and the processes controlling the net flux of 14C out of the Irish Sea, through the North Channel. In this study, both an empirical and a halving time approach indicate that close to 100% of the 14C that is discharged from Sellafield is dispersed beyond the Irish Sea on a time-scale of months in the form of DIC, with little transfer to the PIC, POC, and DOC fractions, indicating that the “dilute and disperse” mechanism is operating satisfactorily. This is consistent with previous research that indicated little transfer of 14C to Irish Sea sediments. While significant 14C enhancements have been observed in the biota of the Irish Sea, this observation is not necessarily in conflict with either of the above as the total biomass has to be taken into account in any calculations of 14C retention within the Irish Sea.
    • The Copper Age in Northern Italy

      Zoppi, U.; Fulcheri, E.; Gambari, F. M.; Hua, Q.; Lawson, E. M.; Micheletti Cremasco, M.; Venturino Gambari, M. (Department of Geosciences, The University of Arizona, 2001-01-01)
      During the period between the IVth and IIIrd millennia BC, profound changes for the ancient populations inhabiting the northern region of Italy occurred. The first Indo-European migrations were altering the ethnographic characteristics and, with the production of the first copper artifacts, the Neolithic Age was drawing to an end. The most significant testimony of that dramatic period is unquestionably the Otztal iceman. In addition, many other valuable archaeological sites, such as Alba (Cuneo, Italy), have been discovered. Although Alba produced the oldest evidence of copper objects in a Neolithic context (5380 +/40 BP; GX-25859-AMS), more recent discoveries have underlined the importance of this archaeological site. In this paper we will report on a series of radiocarbon measurements of bone remnants which, combined with morphologic, stratigraphic, paleoanthropologic, and paleopathologic studies, have allowed us to gain new insights into the culture and chronology of the European Copper Age.
    • The Cave of Theopetra, Kalambaka: Radiocarbon Evidence for 50,000 Years of Human Presence

      Facorellis, Yorgos; Kyparissi, Apostolika Nina; Maniatis, Yannis (Department of Geosciences, The University of Arizona, 2001-01-01)
      The cave of Theopetra is located on the northeast side of a limestone rock formation, 3 km south of Kalambaka (21 degrees 40'46"E, 39 degrees 40'51"N), in Thessaly, central Greece. It is a unique prehistoric site for Greece, as the Middle and Upper Paleolithic, Mesolithic, and Neolithic periods are present here, bridging the Pleistocene with the Holocene. Several alternations of the climate during the Pleistocene are recognized in its stratigraphy. Among the most striking finds, two human skeletons, one from the Upper Paleolithic period after the Last Glacial Maximum and one from the Mesolithic period, should be emphasized, while in a deep Middle Paleolithic layer, the oldest human footprints, with remains of fire, were uncovered. During the 13 years of excavation, evidence of human activity suitable for radiocarbon dating was collected, such as charcoal samples from hearths and bones from the two human skeletons. The use of proportional counters for the measurement of 14C in combination with the recent improvement of the calibration curve has enabled the production of high-precision reliable ages Sixty 14C-dated samples, originating from 19 pits and from depths ranging from 0.10 m to 4.20 m, have already provided an absolute time framework for the use of the cave. The earliest limit of human presence probably exceeds 48,000 BP and the latest reaches World War II. Within these limits the 14C dating of samples from consecutive layers, in combination with the archaeological data, permits the resolution of successive anthropogenic and environmental events.
    • Radiocarbon Chronology of the Earliest Neolithic Sites in East Asia

      Kuzmin, Yaroslav V.; Keally, Charles T. (Department of Geosciences, The University of Arizona, 2001-01-01)
      The radiocarbon age of the earliest pottery from Russian Far East-Gromatukha and Osipovka cultures-is between around 13,300 BP and around 10,400 BP. This shows that the Amur River basin was one of the centers of origin of pottery in East Asia, at the end of the Pleistocene. Today, there are three areas within East Asia with pottery-associated 14C dates between around 14,000 BP and 13,000 BP—Southern China, the Japanese Isles, and Russian Far East.
    • Dating of Ancient Icons from Kiev Art Collections

      Kovalyukh, N.; van der Plicht, J.; Possnert, G.; Skripkin, V.; Chlenova, L. (Department of Geosciences, The University of Arizona, 2001-01-01)
      Icon painting in the Ukraine is rooted in the Byzantine culture, after the conversion to the Christian religion. During the medieval epoch, Kiev became the artistic center for highly skilled icon painters. The icons were painted on woodenboards, specially made for this purpose. Historic dating of some even well-known icons is uncertain or not precise. Here we present for the first time radiocarbon dates for selected icons. Both liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) dating methods were applied, allowing intercomparison.
    • Editorial Board

      Department of Geosciences, The University of Arizona, 2001-01-01